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1 | =head1 NAME |
2 | |
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3 | perlxs - XS language reference manual |
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4 | |
5 | =head1 DESCRIPTION |
6 | |
7 | =head2 Introduction |
8 | |
9 | XS is a language used to create an extension interface |
10 | between Perl and some C library which one wishes to use with |
11 | Perl. The XS interface is combined with the library to |
12 | create a new library which can be linked to Perl. An B<XSUB> |
13 | is a function in the XS language and is the core component |
14 | of the Perl application interface. |
15 | |
16 | The XS compiler is called B<xsubpp>. This compiler will embed |
17 | the constructs necessary to let an XSUB, which is really a C |
18 | function in disguise, manipulate Perl values and creates the |
19 | glue necessary to let Perl access the XSUB. The compiler |
20 | uses B<typemaps> to determine how to map C function parameters |
21 | and variables to Perl values. The default typemap handles |
22 | many common C types. A supplement typemap must be created |
23 | to handle special structures and types for the library being |
24 | linked. |
25 | |
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26 | See L<perlxstut> for a tutorial on the whole extension creation process. |
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27 | |
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28 | Note: For many extensions, Dave Beazley's SWIG system provides a |
29 | significantly more convenient mechanism for creating the XS glue |
30 | code. See L<http://www.cs.utah.edu/~beazley/SWIG> for more |
31 | information. |
32 | |
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33 | =head2 On The Road |
34 | |
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35 | Many of the examples which follow will concentrate on creating an interface |
36 | between Perl and the ONC+ RPC bind library functions. The rpcb_gettime() |
37 | function is used to demonstrate many features of the XS language. This |
38 | function has two parameters; the first is an input parameter and the second |
39 | is an output parameter. The function also returns a status value. |
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40 | |
41 | bool_t rpcb_gettime(const char *host, time_t *timep); |
42 | |
43 | From C this function will be called with the following |
44 | statements. |
45 | |
46 | #include <rpc/rpc.h> |
47 | bool_t status; |
48 | time_t timep; |
49 | status = rpcb_gettime( "localhost", &timep ); |
50 | |
51 | If an XSUB is created to offer a direct translation between this function |
52 | and Perl, then this XSUB will be used from Perl with the following code. |
53 | The $status and $timep variables will contain the output of the function. |
54 | |
55 | use RPC; |
56 | $status = rpcb_gettime( "localhost", $timep ); |
57 | |
58 | The following XS file shows an XS subroutine, or XSUB, which |
59 | demonstrates one possible interface to the rpcb_gettime() |
60 | function. This XSUB represents a direct translation between |
61 | C and Perl and so preserves the interface even from Perl. |
62 | This XSUB will be invoked from Perl with the usage shown |
63 | above. Note that the first three #include statements, for |
64 | C<EXTERN.h>, C<perl.h>, and C<XSUB.h>, will always be present at the |
65 | beginning of an XS file. This approach and others will be |
66 | expanded later in this document. |
67 | |
68 | #include "EXTERN.h" |
69 | #include "perl.h" |
70 | #include "XSUB.h" |
71 | #include <rpc/rpc.h> |
72 | |
73 | MODULE = RPC PACKAGE = RPC |
74 | |
75 | bool_t |
76 | rpcb_gettime(host,timep) |
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77 | char *host |
78 | time_t &timep |
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79 | OUTPUT: |
80 | timep |
81 | |
82 | Any extension to Perl, including those containing XSUBs, |
83 | should have a Perl module to serve as the bootstrap which |
84 | pulls the extension into Perl. This module will export the |
85 | extension's functions and variables to the Perl program and |
86 | will cause the extension's XSUBs to be linked into Perl. |
87 | The following module will be used for most of the examples |
88 | in this document and should be used from Perl with the C<use> |
89 | command as shown earlier. Perl modules are explained in |
90 | more detail later in this document. |
91 | |
92 | package RPC; |
93 | |
94 | require Exporter; |
95 | require DynaLoader; |
96 | @ISA = qw(Exporter DynaLoader); |
97 | @EXPORT = qw( rpcb_gettime ); |
98 | |
99 | bootstrap RPC; |
100 | 1; |
101 | |
102 | Throughout this document a variety of interfaces to the rpcb_gettime() |
103 | XSUB will be explored. The XSUBs will take their parameters in different |
104 | orders or will take different numbers of parameters. In each case the |
105 | XSUB is an abstraction between Perl and the real C rpcb_gettime() |
106 | function, and the XSUB must always ensure that the real rpcb_gettime() |
107 | function is called with the correct parameters. This abstraction will |
108 | allow the programmer to create a more Perl-like interface to the C |
109 | function. |
110 | |
111 | =head2 The Anatomy of an XSUB |
112 | |
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113 | The following XSUB allows a Perl program to access a C library function |
114 | called sin(). The XSUB will imitate the C function which takes a single |
115 | argument and returns a single value. |
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116 | |
117 | double |
118 | sin(x) |
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119 | double x |
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120 | |
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121 | When using C pointers the indirection operator C<*> should be considered |
122 | part of the type and the address operator C<&> should be considered part of |
123 | the variable, as is demonstrated in the rpcb_gettime() function above. See |
124 | the section on typemaps for more about handling qualifiers and unary |
125 | operators in C types. |
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126 | |
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127 | The function name and the return type must be placed on |
128 | separate lines. |
129 | |
130 | INCORRECT CORRECT |
131 | |
132 | double sin(x) double |
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133 | double x sin(x) |
134 | double x |
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135 | |
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136 | The function body may be indented or left-adjusted. The following example |
137 | shows a function with its body left-adjusted. Most examples in this |
138 | document will indent the body. |
139 | |
140 | CORRECT |
141 | |
142 | double |
143 | sin(x) |
144 | double x |
145 | |
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146 | =head2 The Argument Stack |
147 | |
148 | The argument stack is used to store the values which are |
149 | sent as parameters to the XSUB and to store the XSUB's |
150 | return value. In reality all Perl functions keep their |
151 | values on this stack at the same time, each limited to its |
152 | own range of positions on the stack. In this document the |
153 | first position on that stack which belongs to the active |
154 | function will be referred to as position 0 for that function. |
155 | |
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156 | XSUBs refer to their stack arguments with the macro B<ST(x)>, where I<x> |
157 | refers to a position in this XSUB's part of the stack. Position 0 for that |
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158 | function would be known to the XSUB as ST(0). The XSUB's incoming |
159 | parameters and outgoing return values always begin at ST(0). For many |
160 | simple cases the B<xsubpp> compiler will generate the code necessary to |
161 | handle the argument stack by embedding code fragments found in the |
162 | typemaps. In more complex cases the programmer must supply the code. |
163 | |
164 | =head2 The RETVAL Variable |
165 | |
166 | The RETVAL variable is a magic variable which always matches |
167 | the return type of the C library function. The B<xsubpp> compiler will |
168 | supply this variable in each XSUB and by default will use it to hold the |
169 | return value of the C library function being called. In simple cases the |
170 | value of RETVAL will be placed in ST(0) of the argument stack where it can |
171 | be received by Perl as the return value of the XSUB. |
172 | |
173 | If the XSUB has a return type of C<void> then the compiler will |
174 | not supply a RETVAL variable for that function. When using |
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175 | the PPCODE: directive the RETVAL variable is not needed, unless used |
176 | explicitly. |
177 | |
178 | If PPCODE: directive is not used, C<void> return value should be used |
179 | only for subroutines which do not return a value, I<even if> CODE: |
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180 | directive is used which sets ST(0) explicitly. |
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181 | |
182 | Older versions of this document recommended to use C<void> return |
183 | value in such cases. It was discovered that this could lead to |
184 | segfaults in cases when XSUB was I<truely> C<void>. This practice is |
185 | now deprecated, and may be not supported at some future version. Use |
186 | the return value C<SV *> in such cases. (Currently C<xsubpp> contains |
187 | some heuristic code which tries to disambiguate between "truely-void" |
188 | and "old-practice-declared-as-void" functions. Hence your code is at |
189 | mercy of this heuristics unless you use C<SV *> as return value.) |
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190 | |
191 | =head2 The MODULE Keyword |
192 | |
193 | The MODULE keyword is used to start the XS code and to |
194 | specify the package of the functions which are being |
195 | defined. All text preceding the first MODULE keyword is |
196 | considered C code and is passed through to the output |
197 | untouched. Every XS module will have a bootstrap function |
198 | which is used to hook the XSUBs into Perl. The package name |
199 | of this bootstrap function will match the value of the last |
200 | MODULE statement in the XS source files. The value of |
201 | MODULE should always remain constant within the same XS |
202 | file, though this is not required. |
203 | |
204 | The following example will start the XS code and will place |
205 | all functions in a package named RPC. |
206 | |
207 | MODULE = RPC |
208 | |
209 | =head2 The PACKAGE Keyword |
210 | |
211 | When functions within an XS source file must be separated into packages |
212 | the PACKAGE keyword should be used. This keyword is used with the MODULE |
213 | keyword and must follow immediately after it when used. |
214 | |
215 | MODULE = RPC PACKAGE = RPC |
216 | |
217 | [ XS code in package RPC ] |
218 | |
219 | MODULE = RPC PACKAGE = RPCB |
220 | |
221 | [ XS code in package RPCB ] |
222 | |
223 | MODULE = RPC PACKAGE = RPC |
224 | |
225 | [ XS code in package RPC ] |
226 | |
227 | Although this keyword is optional and in some cases provides redundant |
228 | information it should always be used. This keyword will ensure that the |
229 | XSUBs appear in the desired package. |
230 | |
231 | =head2 The PREFIX Keyword |
232 | |
233 | The PREFIX keyword designates prefixes which should be |
234 | removed from the Perl function names. If the C function is |
235 | C<rpcb_gettime()> and the PREFIX value is C<rpcb_> then Perl will |
236 | see this function as C<gettime()>. |
237 | |
238 | This keyword should follow the PACKAGE keyword when used. |
239 | If PACKAGE is not used then PREFIX should follow the MODULE |
240 | keyword. |
241 | |
242 | MODULE = RPC PREFIX = rpc_ |
243 | |
244 | MODULE = RPC PACKAGE = RPCB PREFIX = rpcb_ |
245 | |
246 | =head2 The OUTPUT: Keyword |
247 | |
248 | The OUTPUT: keyword indicates that certain function parameters should be |
249 | updated (new values made visible to Perl) when the XSUB terminates or that |
250 | certain values should be returned to the calling Perl function. For |
251 | simple functions, such as the sin() function above, the RETVAL variable is |
252 | automatically designated as an output value. In more complex functions |
253 | the B<xsubpp> compiler will need help to determine which variables are output |
254 | variables. |
255 | |
256 | This keyword will normally be used to complement the CODE: keyword. |
257 | The RETVAL variable is not recognized as an output variable when the |
258 | CODE: keyword is present. The OUTPUT: keyword is used in this |
259 | situation to tell the compiler that RETVAL really is an output |
260 | variable. |
261 | |
262 | The OUTPUT: keyword can also be used to indicate that function parameters |
263 | are output variables. This may be necessary when a parameter has been |
264 | modified within the function and the programmer would like the update to |
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265 | be seen by Perl. |
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266 | |
267 | bool_t |
268 | rpcb_gettime(host,timep) |
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269 | char *host |
270 | time_t &timep |
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271 | OUTPUT: |
272 | timep |
273 | |
274 | The OUTPUT: keyword will also allow an output parameter to |
275 | be mapped to a matching piece of code rather than to a |
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276 | typemap. |
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277 | |
278 | bool_t |
279 | rpcb_gettime(host,timep) |
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280 | char *host |
281 | time_t &timep |
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282 | OUTPUT: |
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283 | timep sv_setnv(ST(1), (double)timep); |
284 | |
285 | B<xsubpp> emits an automatic C<SvSETMAGIC()> for all parameters in the |
286 | OUTPUT section of the XSUB, except RETVAL. This is the usually desired |
287 | behavior, as it takes care of properly invoking 'set' magic on output |
288 | parameters (needed for hash or array element parameters that must be |
289 | created if they didn't exist). If for some reason, this behavior is |
290 | not desired, the OUTPUT section may contain a C<SETMAGIC: DISABLE> line |
291 | to disable it for the remainder of the parameters in the OUTPUT section. |
292 | Likewise, C<SETMAGIC: ENABLE> can be used to reenable it for the |
293 | remainder of the OUTPUT section. See L<perlguts> for more details |
294 | about 'set' magic. |
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295 | |
296 | =head2 The CODE: Keyword |
297 | |
298 | This keyword is used in more complicated XSUBs which require |
299 | special handling for the C function. The RETVAL variable is |
300 | available but will not be returned unless it is specified |
301 | under the OUTPUT: keyword. |
302 | |
303 | The following XSUB is for a C function which requires special handling of |
304 | its parameters. The Perl usage is given first. |
305 | |
306 | $status = rpcb_gettime( "localhost", $timep ); |
307 | |
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308 | The XSUB follows. |
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309 | |
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310 | bool_t |
311 | rpcb_gettime(host,timep) |
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312 | char *host |
313 | time_t timep |
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314 | CODE: |
315 | RETVAL = rpcb_gettime( host, &timep ); |
316 | OUTPUT: |
317 | timep |
318 | RETVAL |
319 | |
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320 | =head2 The INIT: Keyword |
321 | |
322 | The INIT: keyword allows initialization to be inserted into the XSUB before |
323 | the compiler generates the call to the C function. Unlike the CODE: keyword |
324 | above, this keyword does not affect the way the compiler handles RETVAL. |
325 | |
326 | bool_t |
327 | rpcb_gettime(host,timep) |
328 | char *host |
329 | time_t &timep |
330 | INIT: |
331 | printf("# Host is %s\n", host ); |
332 | OUTPUT: |
333 | timep |
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334 | |
335 | =head2 The NO_INIT Keyword |
336 | |
337 | The NO_INIT keyword is used to indicate that a function |
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338 | parameter is being used only as an output value. The B<xsubpp> |
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339 | compiler will normally generate code to read the values of |
340 | all function parameters from the argument stack and assign |
341 | them to C variables upon entry to the function. NO_INIT |
342 | will tell the compiler that some parameters will be used for |
343 | output rather than for input and that they will be handled |
344 | before the function terminates. |
345 | |
346 | The following example shows a variation of the rpcb_gettime() function. |
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347 | This function uses the timep variable only as an output variable and does |
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348 | not care about its initial contents. |
349 | |
350 | bool_t |
351 | rpcb_gettime(host,timep) |
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352 | char *host |
353 | time_t &timep = NO_INIT |
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354 | OUTPUT: |
355 | timep |
356 | |
357 | =head2 Initializing Function Parameters |
358 | |
359 | Function parameters are normally initialized with their |
360 | values from the argument stack. The typemaps contain the |
361 | code segments which are used to transfer the Perl values to |
362 | the C parameters. The programmer, however, is allowed to |
363 | override the typemaps and supply alternate initialization |
364 | code. |
365 | |
366 | The following code demonstrates how to supply initialization code for |
367 | function parameters. The initialization code is eval'd by the compiler |
368 | before it is added to the output so anything which should be interpreted |
369 | literally, such as double quotes, must be protected with backslashes. |
370 | |
371 | bool_t |
372 | rpcb_gettime(host,timep) |
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373 | char *host = (char *)SvPV(ST(0),na); |
374 | time_t &timep = 0; |
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375 | OUTPUT: |
376 | timep |
377 | |
378 | This should not be used to supply default values for parameters. One |
379 | would normally use this when a function parameter must be processed by |
380 | another library function before it can be used. Default parameters are |
381 | covered in the next section. |
382 | |
383 | =head2 Default Parameter Values |
384 | |
385 | Default values can be specified for function parameters by |
386 | placing an assignment statement in the parameter list. The |
387 | default value may be a number or a string. Defaults should |
388 | always be used on the right-most parameters only. |
389 | |
390 | To allow the XSUB for rpcb_gettime() to have a default host |
391 | value the parameters to the XSUB could be rearranged. The |
392 | XSUB will then call the real rpcb_gettime() function with |
393 | the parameters in the correct order. Perl will call this |
394 | XSUB with either of the following statements. |
395 | |
396 | $status = rpcb_gettime( $timep, $host ); |
397 | |
398 | $status = rpcb_gettime( $timep ); |
399 | |
400 | The XSUB will look like the code which follows. A CODE: |
401 | block is used to call the real rpcb_gettime() function with |
402 | the parameters in the correct order for that function. |
403 | |
404 | bool_t |
405 | rpcb_gettime(timep,host="localhost") |
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406 | char *host |
407 | time_t timep = NO_INIT |
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408 | CODE: |
409 | RETVAL = rpcb_gettime( host, &timep ); |
410 | OUTPUT: |
411 | timep |
412 | RETVAL |
413 | |
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414 | =head2 The PREINIT: Keyword |
415 | |
416 | The PREINIT: keyword allows extra variables to be declared before the |
417 | typemaps are expanded. If a variable is declared in a CODE: block then that |
418 | variable will follow any typemap code. This may result in a C syntax |
419 | error. To force the variable to be declared before the typemap code, place |
420 | it into a PREINIT: block. The PREINIT: keyword may be used one or more |
421 | times within an XSUB. |
422 | |
423 | The following examples are equivalent, but if the code is using complex |
424 | typemaps then the first example is safer. |
425 | |
426 | bool_t |
427 | rpcb_gettime(timep) |
428 | time_t timep = NO_INIT |
429 | PREINIT: |
430 | char *host = "localhost"; |
431 | CODE: |
432 | RETVAL = rpcb_gettime( host, &timep ); |
433 | OUTPUT: |
434 | timep |
435 | RETVAL |
436 | |
437 | A correct, but error-prone example. |
438 | |
439 | bool_t |
440 | rpcb_gettime(timep) |
441 | time_t timep = NO_INIT |
442 | CODE: |
443 | char *host = "localhost"; |
444 | RETVAL = rpcb_gettime( host, &timep ); |
445 | OUTPUT: |
446 | timep |
447 | RETVAL |
448 | |
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449 | =head2 The SCOPE: Keyword |
450 | |
451 | The SCOPE: keyword allows scoping to be enabled for a particular XSUB. If |
452 | enabled, the XSUB will invoke ENTER and LEAVE automatically. |
453 | |
454 | To support potentially complex type mappings, if a typemap entry used |
455 | by this XSUB contains a comment like C</*scope*/> then scoping will |
456 | automatically be enabled for that XSUB. |
457 | |
458 | To enable scoping: |
459 | |
460 | SCOPE: ENABLE |
461 | |
462 | To disable scoping: |
463 | |
464 | SCOPE: DISABLE |
465 | |
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466 | =head2 The INPUT: Keyword |
467 | |
468 | The XSUB's parameters are usually evaluated immediately after entering the |
469 | XSUB. The INPUT: keyword can be used to force those parameters to be |
470 | evaluated a little later. The INPUT: keyword can be used multiple times |
471 | within an XSUB and can be used to list one or more input variables. This |
472 | keyword is used with the PREINIT: keyword. |
473 | |
474 | The following example shows how the input parameter C<timep> can be |
475 | evaluated late, after a PREINIT. |
476 | |
477 | bool_t |
478 | rpcb_gettime(host,timep) |
479 | char *host |
480 | PREINIT: |
481 | time_t tt; |
482 | INPUT: |
483 | time_t timep |
484 | CODE: |
485 | RETVAL = rpcb_gettime( host, &tt ); |
486 | timep = tt; |
487 | OUTPUT: |
488 | timep |
489 | RETVAL |
490 | |
491 | The next example shows each input parameter evaluated late. |
492 | |
493 | bool_t |
494 | rpcb_gettime(host,timep) |
495 | PREINIT: |
496 | time_t tt; |
497 | INPUT: |
498 | char *host |
499 | PREINIT: |
500 | char *h; |
501 | INPUT: |
502 | time_t timep |
503 | CODE: |
504 | h = host; |
505 | RETVAL = rpcb_gettime( h, &tt ); |
506 | timep = tt; |
507 | OUTPUT: |
508 | timep |
509 | RETVAL |
510 | |
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511 | =head2 Variable-length Parameter Lists |
512 | |
513 | XSUBs can have variable-length parameter lists by specifying an ellipsis |
514 | C<(...)> in the parameter list. This use of the ellipsis is similar to that |
515 | found in ANSI C. The programmer is able to determine the number of |
516 | arguments passed to the XSUB by examining the C<items> variable which the |
517 | B<xsubpp> compiler supplies for all XSUBs. By using this mechanism one can |
518 | create an XSUB which accepts a list of parameters of unknown length. |
519 | |
520 | The I<host> parameter for the rpcb_gettime() XSUB can be |
521 | optional so the ellipsis can be used to indicate that the |
522 | XSUB will take a variable number of parameters. Perl should |
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523 | be able to call this XSUB with either of the following statements. |
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524 | |
525 | $status = rpcb_gettime( $timep, $host ); |
526 | |
527 | $status = rpcb_gettime( $timep ); |
528 | |
529 | The XS code, with ellipsis, follows. |
530 | |
531 | bool_t |
532 | rpcb_gettime(timep, ...) |
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533 | time_t timep = NO_INIT |
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534 | PREINIT: |
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535 | char *host = "localhost"; |
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536 | CODE: |
537 | if( items > 1 ) |
538 | host = (char *)SvPV(ST(1), na); |
539 | RETVAL = rpcb_gettime( host, &timep ); |
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540 | OUTPUT: |
541 | timep |
542 | RETVAL |
543 | |
544 | =head2 The PPCODE: Keyword |
545 | |
546 | The PPCODE: keyword is an alternate form of the CODE: keyword and is used |
547 | to tell the B<xsubpp> compiler that the programmer is supplying the code to |
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548 | control the argument stack for the XSUBs return values. Occasionally one |
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549 | will want an XSUB to return a list of values rather than a single value. |
550 | In these cases one must use PPCODE: and then explicitly push the list of |
551 | values on the stack. The PPCODE: and CODE: keywords are not used |
552 | together within the same XSUB. |
553 | |
554 | The following XSUB will call the C rpcb_gettime() function |
555 | and will return its two output values, timep and status, to |
556 | Perl as a single list. |
557 | |
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558 | void |
559 | rpcb_gettime(host) |
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560 | char *host |
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561 | PREINIT: |
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562 | time_t timep; |
563 | bool_t status; |
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564 | PPCODE: |
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565 | status = rpcb_gettime( host, &timep ); |
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566 | EXTEND(SP, 2); |
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567 | PUSHs(sv_2mortal(newSViv(status))); |
568 | PUSHs(sv_2mortal(newSViv(timep))); |
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569 | |
570 | Notice that the programmer must supply the C code necessary |
571 | to have the real rpcb_gettime() function called and to have |
572 | the return values properly placed on the argument stack. |
573 | |
574 | The C<void> return type for this function tells the B<xsubpp> compiler that |
575 | the RETVAL variable is not needed or used and that it should not be created. |
576 | In most scenarios the void return type should be used with the PPCODE: |
577 | directive. |
578 | |
579 | The EXTEND() macro is used to make room on the argument |
580 | stack for 2 return values. The PPCODE: directive causes the |
924508f0 |
581 | B<xsubpp> compiler to create a stack pointer available as C<SP>, and it |
a0d0e21e |
582 | is this pointer which is being used in the EXTEND() macro. |
583 | The values are then pushed onto the stack with the PUSHs() |
584 | macro. |
585 | |
586 | Now the rpcb_gettime() function can be used from Perl with |
587 | the following statement. |
588 | |
589 | ($status, $timep) = rpcb_gettime("localhost"); |
590 | |
ef50df4b |
591 | When handling output parameters with a PPCODE section, be sure to handle |
592 | 'set' magic properly. See L<perlguts> for details about 'set' magic. |
593 | |
a0d0e21e |
594 | =head2 Returning Undef And Empty Lists |
595 | |
5f05dabc |
596 | Occasionally the programmer will want to return simply |
a0d0e21e |
597 | C<undef> or an empty list if a function fails rather than a |
598 | separate status value. The rpcb_gettime() function offers |
599 | just this situation. If the function succeeds we would like |
600 | to have it return the time and if it fails we would like to |
601 | have undef returned. In the following Perl code the value |
602 | of $timep will either be undef or it will be a valid time. |
603 | |
604 | $timep = rpcb_gettime( "localhost" ); |
605 | |
7b8d334a |
606 | The following XSUB uses the C<SV *> return type as a mnemonic only, |
e7ea3e70 |
607 | and uses a CODE: block to indicate to the compiler |
a0d0e21e |
608 | that the programmer has supplied all the necessary code. The |
609 | sv_newmortal() call will initialize the return value to undef, making that |
610 | the default return value. |
611 | |
e7ea3e70 |
612 | SV * |
a0d0e21e |
613 | rpcb_gettime(host) |
614 | char * host |
c07a80fd |
615 | PREINIT: |
a0d0e21e |
616 | time_t timep; |
617 | bool_t x; |
c07a80fd |
618 | CODE: |
a0d0e21e |
619 | ST(0) = sv_newmortal(); |
620 | if( rpcb_gettime( host, &timep ) ) |
621 | sv_setnv( ST(0), (double)timep); |
a0d0e21e |
622 | |
623 | The next example demonstrates how one would place an explicit undef in the |
624 | return value, should the need arise. |
625 | |
e7ea3e70 |
626 | SV * |
a0d0e21e |
627 | rpcb_gettime(host) |
628 | char * host |
c07a80fd |
629 | PREINIT: |
a0d0e21e |
630 | time_t timep; |
631 | bool_t x; |
c07a80fd |
632 | CODE: |
a0d0e21e |
633 | ST(0) = sv_newmortal(); |
634 | if( rpcb_gettime( host, &timep ) ){ |
635 | sv_setnv( ST(0), (double)timep); |
636 | } |
637 | else{ |
638 | ST(0) = &sv_undef; |
639 | } |
a0d0e21e |
640 | |
641 | To return an empty list one must use a PPCODE: block and |
642 | then not push return values on the stack. |
643 | |
644 | void |
645 | rpcb_gettime(host) |
8e07c86e |
646 | char *host |
c07a80fd |
647 | PREINIT: |
a0d0e21e |
648 | time_t timep; |
c07a80fd |
649 | PPCODE: |
a0d0e21e |
650 | if( rpcb_gettime( host, &timep ) ) |
cb1a09d0 |
651 | PUSHs(sv_2mortal(newSViv(timep))); |
a0d0e21e |
652 | else{ |
653 | /* Nothing pushed on stack, so an empty */ |
654 | /* list is implicitly returned. */ |
655 | } |
a0d0e21e |
656 | |
f27cfbbe |
657 | Some people may be inclined to include an explicit C<return> in the above |
658 | XSUB, rather than letting control fall through to the end. In those |
659 | situations C<XSRETURN_EMPTY> should be used, instead. This will ensure that |
660 | the XSUB stack is properly adjusted. Consult L<perlguts/"API LISTING"> for |
661 | other C<XSRETURN> macros. |
662 | |
4633a7c4 |
663 | =head2 The REQUIRE: Keyword |
664 | |
665 | The REQUIRE: keyword is used to indicate the minimum version of the |
666 | B<xsubpp> compiler needed to compile the XS module. An XS module which |
5f05dabc |
667 | contains the following statement will compile with only B<xsubpp> version |
4633a7c4 |
668 | 1.922 or greater: |
669 | |
670 | REQUIRE: 1.922 |
671 | |
a0d0e21e |
672 | =head2 The CLEANUP: Keyword |
673 | |
674 | This keyword can be used when an XSUB requires special cleanup procedures |
675 | before it terminates. When the CLEANUP: keyword is used it must follow |
676 | any CODE:, PPCODE:, or OUTPUT: blocks which are present in the XSUB. The |
677 | code specified for the cleanup block will be added as the last statements |
678 | in the XSUB. |
679 | |
680 | =head2 The BOOT: Keyword |
681 | |
682 | The BOOT: keyword is used to add code to the extension's bootstrap |
683 | function. The bootstrap function is generated by the B<xsubpp> compiler and |
684 | normally holds the statements necessary to register any XSUBs with Perl. |
685 | With the BOOT: keyword the programmer can tell the compiler to add extra |
686 | statements to the bootstrap function. |
687 | |
688 | This keyword may be used any time after the first MODULE keyword and should |
689 | appear on a line by itself. The first blank line after the keyword will |
690 | terminate the code block. |
691 | |
692 | BOOT: |
693 | # The following message will be printed when the |
694 | # bootstrap function executes. |
695 | printf("Hello from the bootstrap!\n"); |
696 | |
c07a80fd |
697 | =head2 The VERSIONCHECK: Keyword |
698 | |
699 | The VERSIONCHECK: keyword corresponds to B<xsubpp>'s C<-versioncheck> and |
5f05dabc |
700 | C<-noversioncheck> options. This keyword overrides the command line |
c07a80fd |
701 | options. Version checking is enabled by default. When version checking is |
702 | enabled the XS module will attempt to verify that its version matches the |
703 | version of the PM module. |
704 | |
705 | To enable version checking: |
706 | |
707 | VERSIONCHECK: ENABLE |
708 | |
709 | To disable version checking: |
710 | |
711 | VERSIONCHECK: DISABLE |
712 | |
713 | =head2 The PROTOTYPES: Keyword |
714 | |
715 | The PROTOTYPES: keyword corresponds to B<xsubpp>'s C<-prototypes> and |
54310121 |
716 | C<-noprototypes> options. This keyword overrides the command line options. |
c07a80fd |
717 | Prototypes are enabled by default. When prototypes are enabled XSUBs will |
718 | be given Perl prototypes. This keyword may be used multiple times in an XS |
719 | module to enable and disable prototypes for different parts of the module. |
720 | |
721 | To enable prototypes: |
722 | |
723 | PROTOTYPES: ENABLE |
724 | |
725 | To disable prototypes: |
726 | |
727 | PROTOTYPES: DISABLE |
728 | |
729 | =head2 The PROTOTYPE: Keyword |
730 | |
731 | This keyword is similar to the PROTOTYPES: keyword above but can be used to |
732 | force B<xsubpp> to use a specific prototype for the XSUB. This keyword |
733 | overrides all other prototype options and keywords but affects only the |
734 | current XSUB. Consult L<perlsub/Prototypes> for information about Perl |
735 | prototypes. |
736 | |
737 | bool_t |
738 | rpcb_gettime(timep, ...) |
739 | time_t timep = NO_INIT |
740 | PROTOTYPE: $;$ |
741 | PREINIT: |
742 | char *host = "localhost"; |
743 | CODE: |
744 | if( items > 1 ) |
745 | host = (char *)SvPV(ST(1), na); |
746 | RETVAL = rpcb_gettime( host, &timep ); |
747 | OUTPUT: |
748 | timep |
749 | RETVAL |
750 | |
751 | =head2 The ALIAS: Keyword |
752 | |
68dc0745 |
753 | The ALIAS: keyword allows an XSUB to have two more unique Perl names |
c07a80fd |
754 | and to know which of those names was used when it was invoked. The Perl |
755 | names may be fully-qualified with package names. Each alias is given an |
756 | index. The compiler will setup a variable called C<ix> which contain the |
757 | index of the alias which was used. When the XSUB is called with its |
758 | declared name C<ix> will be 0. |
759 | |
760 | The following example will create aliases C<FOO::gettime()> and |
761 | C<BAR::getit()> for this function. |
762 | |
763 | bool_t |
764 | rpcb_gettime(host,timep) |
765 | char *host |
766 | time_t &timep |
767 | ALIAS: |
768 | FOO::gettime = 1 |
769 | BAR::getit = 2 |
770 | INIT: |
771 | printf("# ix = %d\n", ix ); |
772 | OUTPUT: |
773 | timep |
774 | |
775 | =head2 The INCLUDE: Keyword |
776 | |
777 | This keyword can be used to pull other files into the XS module. The other |
778 | files may have XS code. INCLUDE: can also be used to run a command to |
779 | generate the XS code to be pulled into the module. |
780 | |
781 | The file F<Rpcb1.xsh> contains our C<rpcb_gettime()> function: |
782 | |
783 | bool_t |
784 | rpcb_gettime(host,timep) |
785 | char *host |
786 | time_t &timep |
787 | OUTPUT: |
788 | timep |
789 | |
790 | The XS module can use INCLUDE: to pull that file into it. |
791 | |
792 | INCLUDE: Rpcb1.xsh |
793 | |
794 | If the parameters to the INCLUDE: keyword are followed by a pipe (C<|>) then |
795 | the compiler will interpret the parameters as a command. |
796 | |
797 | INCLUDE: cat Rpcb1.xsh | |
798 | |
799 | =head2 The CASE: Keyword |
800 | |
801 | The CASE: keyword allows an XSUB to have multiple distinct parts with each |
802 | part acting as a virtual XSUB. CASE: is greedy and if it is used then all |
803 | other XS keywords must be contained within a CASE:. This means nothing may |
804 | precede the first CASE: in the XSUB and anything following the last CASE: is |
805 | included in that case. |
806 | |
807 | A CASE: might switch via a parameter of the XSUB, via the C<ix> ALIAS: |
808 | variable (see L<"The ALIAS: Keyword">), or maybe via the C<items> variable |
809 | (see L<"Variable-length Parameter Lists">). The last CASE: becomes the |
810 | B<default> case if it is not associated with a conditional. The following |
811 | example shows CASE switched via C<ix> with a function C<rpcb_gettime()> |
812 | having an alias C<x_gettime()>. When the function is called as |
b772cb6e |
813 | C<rpcb_gettime()> its parameters are the usual C<(char *host, time_t *timep)>, |
814 | but when the function is called as C<x_gettime()> its parameters are |
c07a80fd |
815 | reversed, C<(time_t *timep, char *host)>. |
816 | |
817 | long |
818 | rpcb_gettime(a,b) |
819 | CASE: ix == 1 |
820 | ALIAS: |
821 | x_gettime = 1 |
822 | INPUT: |
823 | # 'a' is timep, 'b' is host |
824 | char *b |
825 | time_t a = NO_INIT |
826 | CODE: |
827 | RETVAL = rpcb_gettime( b, &a ); |
828 | OUTPUT: |
829 | a |
830 | RETVAL |
831 | CASE: |
832 | # 'a' is host, 'b' is timep |
833 | char *a |
834 | time_t &b = NO_INIT |
835 | OUTPUT: |
836 | b |
837 | RETVAL |
838 | |
839 | That function can be called with either of the following statements. Note |
840 | the different argument lists. |
841 | |
842 | $status = rpcb_gettime( $host, $timep ); |
843 | |
844 | $status = x_gettime( $timep, $host ); |
845 | |
846 | =head2 The & Unary Operator |
847 | |
848 | The & unary operator is used to tell the compiler that it should dereference |
849 | the object when it calls the C function. This is used when a CODE: block is |
850 | not used and the object is a not a pointer type (the object is an C<int> or |
851 | C<long> but not a C<int*> or C<long*>). |
852 | |
853 | The following XSUB will generate incorrect C code. The xsubpp compiler will |
854 | turn this into code which calls C<rpcb_gettime()> with parameters C<(char |
855 | *host, time_t timep)>, but the real C<rpcb_gettime()> wants the C<timep> |
856 | parameter to be of type C<time_t*> rather than C<time_t>. |
857 | |
858 | bool_t |
859 | rpcb_gettime(host,timep) |
860 | char *host |
861 | time_t timep |
862 | OUTPUT: |
863 | timep |
864 | |
865 | That problem is corrected by using the C<&> operator. The xsubpp compiler |
866 | will now turn this into code which calls C<rpcb_gettime()> correctly with |
867 | parameters C<(char *host, time_t *timep)>. It does this by carrying the |
868 | C<&> through, so the function call looks like C<rpcb_gettime(host, &timep)>. |
869 | |
870 | bool_t |
871 | rpcb_gettime(host,timep) |
872 | char *host |
873 | time_t &timep |
874 | OUTPUT: |
875 | timep |
876 | |
a0d0e21e |
877 | =head2 Inserting Comments and C Preprocessor Directives |
878 | |
f27cfbbe |
879 | C preprocessor directives are allowed within BOOT:, PREINIT: INIT:, |
5f05dabc |
880 | CODE:, PPCODE:, and CLEANUP: blocks, as well as outside the functions. |
f27cfbbe |
881 | Comments are allowed anywhere after the MODULE keyword. The compiler |
882 | will pass the preprocessor directives through untouched and will remove |
883 | the commented lines. |
b772cb6e |
884 | |
f27cfbbe |
885 | Comments can be added to XSUBs by placing a C<#> as the first |
886 | non-whitespace of a line. Care should be taken to avoid making the |
887 | comment look like a C preprocessor directive, lest it be interpreted as |
888 | such. The simplest way to prevent this is to put whitespace in front of |
889 | the C<#>. |
890 | |
f27cfbbe |
891 | If you use preprocessor directives to choose one of two |
892 | versions of a function, use |
893 | |
894 | #if ... version1 |
895 | #else /* ... version2 */ |
896 | #endif |
897 | |
898 | and not |
899 | |
900 | #if ... version1 |
901 | #endif |
902 | #if ... version2 |
903 | #endif |
904 | |
905 | because otherwise xsubpp will believe that you made a duplicate |
906 | definition of the function. Also, put a blank line before the |
907 | #else/#endif so it will not be seen as part of the function body. |
a0d0e21e |
908 | |
909 | =head2 Using XS With C++ |
910 | |
911 | If a function is defined as a C++ method then it will assume |
912 | its first argument is an object pointer. The object pointer |
913 | will be stored in a variable called THIS. The object should |
914 | have been created by C++ with the new() function and should |
cb1a09d0 |
915 | be blessed by Perl with the sv_setref_pv() macro. The |
916 | blessing of the object by Perl can be handled by a typemap. An example |
917 | typemap is shown at the end of this section. |
a0d0e21e |
918 | |
919 | If the method is defined as static it will call the C++ |
920 | function using the class::method() syntax. If the method is not static |
f27cfbbe |
921 | the function will be called using the THIS-E<gt>method() syntax. |
a0d0e21e |
922 | |
cb1a09d0 |
923 | The next examples will use the following C++ class. |
a0d0e21e |
924 | |
a5f75d66 |
925 | class color { |
cb1a09d0 |
926 | public: |
a5f75d66 |
927 | color(); |
928 | ~color(); |
cb1a09d0 |
929 | int blue(); |
930 | void set_blue( int ); |
931 | |
932 | private: |
933 | int c_blue; |
934 | }; |
935 | |
936 | The XSUBs for the blue() and set_blue() methods are defined with the class |
937 | name but the parameter for the object (THIS, or "self") is implicit and is |
938 | not listed. |
939 | |
940 | int |
941 | color::blue() |
a0d0e21e |
942 | |
943 | void |
cb1a09d0 |
944 | color::set_blue( val ) |
945 | int val |
a0d0e21e |
946 | |
cb1a09d0 |
947 | Both functions will expect an object as the first parameter. The xsubpp |
948 | compiler will call that object C<THIS> and will use it to call the specified |
949 | method. So in the C++ code the blue() and set_blue() methods will be called |
950 | in the following manner. |
a0d0e21e |
951 | |
cb1a09d0 |
952 | RETVAL = THIS->blue(); |
a0d0e21e |
953 | |
cb1a09d0 |
954 | THIS->set_blue( val ); |
a0d0e21e |
955 | |
cb1a09d0 |
956 | If the function's name is B<DESTROY> then the C++ C<delete> function will be |
957 | called and C<THIS> will be given as its parameter. |
a0d0e21e |
958 | |
d1b91892 |
959 | void |
cb1a09d0 |
960 | color::DESTROY() |
961 | |
962 | The C++ code will call C<delete>. |
963 | |
964 | delete THIS; |
a0d0e21e |
965 | |
cb1a09d0 |
966 | If the function's name is B<new> then the C++ C<new> function will be called |
967 | to create a dynamic C++ object. The XSUB will expect the class name, which |
968 | will be kept in a variable called C<CLASS>, to be given as the first |
969 | argument. |
a0d0e21e |
970 | |
cb1a09d0 |
971 | color * |
972 | color::new() |
a0d0e21e |
973 | |
cb1a09d0 |
974 | The C++ code will call C<new>. |
a0d0e21e |
975 | |
cb1a09d0 |
976 | RETVAL = new color(); |
977 | |
978 | The following is an example of a typemap that could be used for this C++ |
979 | example. |
980 | |
981 | TYPEMAP |
982 | color * O_OBJECT |
983 | |
984 | OUTPUT |
985 | # The Perl object is blessed into 'CLASS', which should be a |
986 | # char* having the name of the package for the blessing. |
987 | O_OBJECT |
988 | sv_setref_pv( $arg, CLASS, (void*)$var ); |
a6006777 |
989 | |
cb1a09d0 |
990 | INPUT |
991 | O_OBJECT |
992 | if( sv_isobject($arg) && (SvTYPE(SvRV($arg)) == SVt_PVMG) ) |
993 | $var = ($type)SvIV((SV*)SvRV( $arg )); |
994 | else{ |
995 | warn( \"${Package}::$func_name() -- $var is not a blessed SV reference\" ); |
996 | XSRETURN_UNDEF; |
997 | } |
a0d0e21e |
998 | |
d1b91892 |
999 | =head2 Interface Strategy |
a0d0e21e |
1000 | |
1001 | When designing an interface between Perl and a C library a straight |
1002 | translation from C to XS is often sufficient. The interface will often be |
1003 | very C-like and occasionally nonintuitive, especially when the C function |
1004 | modifies one of its parameters. In cases where the programmer wishes to |
1005 | create a more Perl-like interface the following strategy may help to |
1006 | identify the more critical parts of the interface. |
1007 | |
1008 | Identify the C functions which modify their parameters. The XSUBs for |
1009 | these functions may be able to return lists to Perl, or may be |
1010 | candidates to return undef or an empty list in case of failure. |
1011 | |
d1b91892 |
1012 | Identify which values are used by only the C and XSUB functions |
a0d0e21e |
1013 | themselves. If Perl does not need to access the contents of the value |
1014 | then it may not be necessary to provide a translation for that value |
1015 | from C to Perl. |
1016 | |
1017 | Identify the pointers in the C function parameter lists and return |
1018 | values. Some pointers can be handled in XS with the & unary operator on |
1019 | the variable name while others will require the use of the * operator on |
1020 | the type name. In general it is easier to work with the & operator. |
1021 | |
1022 | Identify the structures used by the C functions. In many |
1023 | cases it may be helpful to use the T_PTROBJ typemap for |
1024 | these structures so they can be manipulated by Perl as |
1025 | blessed objects. |
1026 | |
a0d0e21e |
1027 | =head2 Perl Objects And C Structures |
1028 | |
1029 | When dealing with C structures one should select either |
1030 | B<T_PTROBJ> or B<T_PTRREF> for the XS type. Both types are |
1031 | designed to handle pointers to complex objects. The |
1032 | T_PTRREF type will allow the Perl object to be unblessed |
1033 | while the T_PTROBJ type requires that the object be blessed. |
1034 | By using T_PTROBJ one can achieve a form of type-checking |
d1b91892 |
1035 | because the XSUB will attempt to verify that the Perl object |
a0d0e21e |
1036 | is of the expected type. |
1037 | |
1038 | The following XS code shows the getnetconfigent() function which is used |
8e07c86e |
1039 | with ONC+ TIRPC. The getnetconfigent() function will return a pointer to a |
a0d0e21e |
1040 | C structure and has the C prototype shown below. The example will |
1041 | demonstrate how the C pointer will become a Perl reference. Perl will |
1042 | consider this reference to be a pointer to a blessed object and will |
1043 | attempt to call a destructor for the object. A destructor will be |
1044 | provided in the XS source to free the memory used by getnetconfigent(). |
1045 | Destructors in XS can be created by specifying an XSUB function whose name |
1046 | ends with the word B<DESTROY>. XS destructors can be used to free memory |
1047 | which may have been malloc'd by another XSUB. |
1048 | |
1049 | struct netconfig *getnetconfigent(const char *netid); |
1050 | |
1051 | A C<typedef> will be created for C<struct netconfig>. The Perl |
1052 | object will be blessed in a class matching the name of the C |
1053 | type, with the tag C<Ptr> appended, and the name should not |
1054 | have embedded spaces if it will be a Perl package name. The |
1055 | destructor will be placed in a class corresponding to the |
1056 | class of the object and the PREFIX keyword will be used to |
1057 | trim the name to the word DESTROY as Perl will expect. |
1058 | |
1059 | typedef struct netconfig Netconfig; |
1060 | |
1061 | MODULE = RPC PACKAGE = RPC |
1062 | |
1063 | Netconfig * |
1064 | getnetconfigent(netid) |
8e07c86e |
1065 | char *netid |
a0d0e21e |
1066 | |
1067 | MODULE = RPC PACKAGE = NetconfigPtr PREFIX = rpcb_ |
1068 | |
1069 | void |
1070 | rpcb_DESTROY(netconf) |
8e07c86e |
1071 | Netconfig *netconf |
a0d0e21e |
1072 | CODE: |
1073 | printf("Now in NetconfigPtr::DESTROY\n"); |
1074 | free( netconf ); |
1075 | |
1076 | This example requires the following typemap entry. Consult the typemap |
1077 | section for more information about adding new typemaps for an extension. |
1078 | |
1079 | TYPEMAP |
1080 | Netconfig * T_PTROBJ |
1081 | |
1082 | This example will be used with the following Perl statements. |
1083 | |
1084 | use RPC; |
1085 | $netconf = getnetconfigent("udp"); |
1086 | |
1087 | When Perl destroys the object referenced by $netconf it will send the |
1088 | object to the supplied XSUB DESTROY function. Perl cannot determine, and |
1089 | does not care, that this object is a C struct and not a Perl object. In |
1090 | this sense, there is no difference between the object created by the |
1091 | getnetconfigent() XSUB and an object created by a normal Perl subroutine. |
1092 | |
a0d0e21e |
1093 | =head2 The Typemap |
1094 | |
1095 | The typemap is a collection of code fragments which are used by the B<xsubpp> |
1096 | compiler to map C function parameters and values to Perl values. The |
1097 | typemap file may consist of three sections labeled C<TYPEMAP>, C<INPUT>, and |
1098 | C<OUTPUT>. The INPUT section tells the compiler how to translate Perl values |
1099 | into variables of certain C types. The OUTPUT section tells the compiler |
1100 | how to translate the values from certain C types into values Perl can |
1101 | understand. The TYPEMAP section tells the compiler which of the INPUT and |
1102 | OUTPUT code fragments should be used to map a given C type to a Perl value. |
1103 | Each of the sections of the typemap must be preceded by one of the TYPEMAP, |
1104 | INPUT, or OUTPUT keywords. |
1105 | |
1106 | The default typemap in the C<ext> directory of the Perl source contains many |
1107 | useful types which can be used by Perl extensions. Some extensions define |
1108 | additional typemaps which they keep in their own directory. These |
1109 | additional typemaps may reference INPUT and OUTPUT maps in the main |
1110 | typemap. The B<xsubpp> compiler will allow the extension's own typemap to |
1111 | override any mappings which are in the default typemap. |
1112 | |
1113 | Most extensions which require a custom typemap will need only the TYPEMAP |
1114 | section of the typemap file. The custom typemap used in the |
1115 | getnetconfigent() example shown earlier demonstrates what may be the typical |
1116 | use of extension typemaps. That typemap is used to equate a C structure |
1117 | with the T_PTROBJ typemap. The typemap used by getnetconfigent() is shown |
1118 | here. Note that the C type is separated from the XS type with a tab and |
1119 | that the C unary operator C<*> is considered to be a part of the C type name. |
1120 | |
1121 | TYPEMAP |
1122 | Netconfig *<tab>T_PTROBJ |
1123 | |
1748e8dd |
1124 | Here's a more complicated example: suppose that you wanted C<struct |
1125 | netconfig> to be blessed into the class C<Net::Config>. One way to do |
1126 | this is to use underscores (_) to separate package names, as follows: |
1127 | |
1128 | typedef struct netconfig * Net_Config; |
1129 | |
1130 | And then provide a typemap entry C<T_PTROBJ_SPECIAL> that maps underscores to |
1131 | double-colons (::), and declare C<Net_Config> to be of that type: |
1132 | |
1133 | |
1134 | TYPEMAP |
1135 | Net_Config T_PTROBJ_SPECIAL |
1136 | |
1137 | INPUT |
1138 | T_PTROBJ_SPECIAL |
1139 | if (sv_derived_from($arg, \"${(my $ntt=$ntype)=~s/_/::/g;\$ntt}\")) { |
1140 | IV tmp = SvIV((SV*)SvRV($arg)); |
1141 | $var = ($type) tmp; |
1142 | } |
1143 | else |
1144 | croak(\"$var is not of type ${(my $ntt=$ntype)=~s/_/::/g;\$ntt}\") |
1145 | |
1146 | OUTPUT |
1147 | T_PTROBJ_SPECIAL |
1148 | sv_setref_pv($arg, \"${(my $ntt=$ntype)=~s/_/::/g;\$ntt}\", |
1149 | (void*)$var); |
1150 | |
1151 | The INPUT and OUTPUT sections substitute underscores for double-colons |
1152 | on the fly, giving the desired effect. This example demonstrates some |
1153 | of the power and versatility of the typemap facility. |
1154 | |
a0d0e21e |
1155 | =head1 EXAMPLES |
1156 | |
1157 | File C<RPC.xs>: Interface to some ONC+ RPC bind library functions. |
1158 | |
1159 | #include "EXTERN.h" |
1160 | #include "perl.h" |
1161 | #include "XSUB.h" |
1162 | |
1163 | #include <rpc/rpc.h> |
1164 | |
1165 | typedef struct netconfig Netconfig; |
1166 | |
1167 | MODULE = RPC PACKAGE = RPC |
1168 | |
e7ea3e70 |
1169 | SV * |
a0d0e21e |
1170 | rpcb_gettime(host="localhost") |
8e07c86e |
1171 | char *host |
c07a80fd |
1172 | PREINIT: |
a0d0e21e |
1173 | time_t timep; |
c07a80fd |
1174 | CODE: |
a0d0e21e |
1175 | ST(0) = sv_newmortal(); |
1176 | if( rpcb_gettime( host, &timep ) ) |
1177 | sv_setnv( ST(0), (double)timep ); |
a0d0e21e |
1178 | |
1179 | Netconfig * |
1180 | getnetconfigent(netid="udp") |
8e07c86e |
1181 | char *netid |
a0d0e21e |
1182 | |
1183 | MODULE = RPC PACKAGE = NetconfigPtr PREFIX = rpcb_ |
1184 | |
1185 | void |
1186 | rpcb_DESTROY(netconf) |
8e07c86e |
1187 | Netconfig *netconf |
a0d0e21e |
1188 | CODE: |
1189 | printf("NetconfigPtr::DESTROY\n"); |
1190 | free( netconf ); |
1191 | |
1192 | File C<typemap>: Custom typemap for RPC.xs. |
1193 | |
1194 | TYPEMAP |
1195 | Netconfig * T_PTROBJ |
1196 | |
1197 | File C<RPC.pm>: Perl module for the RPC extension. |
1198 | |
1199 | package RPC; |
1200 | |
1201 | require Exporter; |
1202 | require DynaLoader; |
1203 | @ISA = qw(Exporter DynaLoader); |
1204 | @EXPORT = qw(rpcb_gettime getnetconfigent); |
1205 | |
1206 | bootstrap RPC; |
1207 | 1; |
1208 | |
1209 | File C<rpctest.pl>: Perl test program for the RPC extension. |
1210 | |
1211 | use RPC; |
1212 | |
1213 | $netconf = getnetconfigent(); |
1214 | $a = rpcb_gettime(); |
1215 | print "time = $a\n"; |
1216 | print "netconf = $netconf\n"; |
1217 | |
1218 | $netconf = getnetconfigent("tcp"); |
1219 | $a = rpcb_gettime("poplar"); |
1220 | print "time = $a\n"; |
1221 | print "netconf = $netconf\n"; |
1222 | |
1223 | |
c07a80fd |
1224 | =head1 XS VERSION |
1225 | |
f27cfbbe |
1226 | This document covers features supported by C<xsubpp> 1.935. |
c07a80fd |
1227 | |
a0d0e21e |
1228 | =head1 AUTHOR |
1229 | |
9607fc9c |
1230 | Dean Roehrich <F<roehrich@cray.com>> |
b772cb6e |
1231 | Jul 8, 1996 |