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