X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlxs.pod;h=98a983422f1ebd55ac7776ef72cdecec399e3c25;hb=0244c3a403af2426ac6678d042024bb183ebbfa9;hp=df2aefa0b6da254928f0d159ed51b97a117e9f3a;hpb=4633a7c4bad06b471d9310620b7fe8ddd158cccd;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perlxs.pod b/pod/perlxs.pod index df2aefa..98a9834 100644 --- a/pod/perlxs.pod +++ b/pod/perlxs.pod @@ -23,47 +23,20 @@ many common C types. A supplement typemap must be created to handle special structures and types for the library being linked. -=head2 Getting Started - -A new extension should begin with the B tool. This will generate -templates for the new Perl module (PM), the XS source file (XS), the MANIFEST -file, and the Makefile.PL (PL) files. The Makefile.PL file is a Perl script -which will generate a Makefile. This makefile knows how to find and run -xsubpp for your extension. When you type "make" your XS file will be run -through xsubpp and a C file will be produced. Then the C file will be -compiled. A simple example looks like this for an example module named -B: - - $ h2xs -Afn Foo - $ cd ext/Foo - $ ls - Foo.pm Foo.xs MANIFEST Makefile.PL - $ perl5 Makefile.PL - $ ls - Foo.pm Foo.xs MANIFEST Makefile.PL Makefile - $ - $ make - for a tutorial on the whole extension creation process. + +Note: For many extensions, Dave Beazley's SWIG system provides a +significantly more convenient mechanism for creating the XS glue +code. See L for more +information. =head2 On The Road -Many of the examples which follow will concentrate on creating an -interface between Perl and the ONC+ RPC bind library functions. -Specifically, the rpcb_gettime() function will be used to demonstrate many -features of the XS language. This function has two parameters; the first -is an input parameter and the second is an output parameter. The function -also returns a status value. +Many of the examples which follow will concentrate on creating an interface +between Perl and the ONC+ RPC bind library functions. The rpcb_gettime() +function is used to demonstrate many features of the XS language. This +function has two parameters; the first is an input parameter and the second +is an output parameter. The function also returns a status value. bool_t rpcb_gettime(const char *host, time_t *timep); @@ -160,6 +133,16 @@ separate lines. double x sin(x) double x +The function body may be indented or left-adjusted. The following example +shows a function with its body left-adjusted. Most examples in this +document will indent the body. + + CORRECT + + double + sin(x) + double x + =head2 The Argument Stack The argument stack is used to store the values which are @@ -189,7 +172,21 @@ be received by Perl as the return value of the XSUB. If the XSUB has a return type of C then the compiler will not supply a RETVAL variable for that function. When using -the PPCODE: directive the RETVAL variable may not be needed. +the PPCODE: directive the RETVAL variable is not needed, unless used +explicitly. + +If PPCODE: directive is not used, C return value should be used +only for subroutines which do not return a value, I CODE: +directive is used which sets ST(0) explicitly. + +Older versions of this document recommended to use C return +value in such cases. It was discovered that this could lead to +segfaults in cases when XSUB was I C. This practice is +now deprecated, and may be not supported at some future version. Use +the return value C in such cases. (Currently C contains +some heuristic code which tries to disambiguate between "truly-void" +and "old-practice-declared-as-void" functions. Hence your code is at +mercy of this heuristics unless you use C as return value.) =head2 The MODULE Keyword @@ -285,6 +282,17 @@ typemap. OUTPUT: timep sv_setnv(ST(1), (double)timep); +B emits an automatic C for all parameters in the +OUTPUT section of the XSUB, except RETVAL. This is the usually desired +behavior, as it takes care of properly invoking 'set' magic on output +parameters (needed for hash or array element parameters that must be +created if they didn't exist). If for some reason, this behavior is +not desired, the OUTPUT section may contain a C line +to disable it for the remainder of the parameters in the OUTPUT section. +Likewise, C can be used to reenable it for the +remainder of the OUTPUT section. See L for more details +about 'set' magic. + =head2 The CODE: Keyword This keyword is used in more complicated XSUBs which require @@ -297,7 +305,7 @@ its parameters. The Perl usage is given first. $status = rpcb_gettime( "localhost", $timep ); -The XSUB follows. +The XSUB follows. bool_t rpcb_gettime(host,timep) @@ -309,15 +317,25 @@ The XSUB follows. timep RETVAL -In many of the examples shown here the CODE: block (and -other blocks) will often be contained within braces ( C<{> and -C<}> ). This protects the CODE: block from complex INPUT -typemaps and ensures the resulting C code is legal. +=head2 The INIT: Keyword + +The INIT: keyword allows initialization to be inserted into the XSUB before +the compiler generates the call to the C function. Unlike the CODE: keyword +above, this keyword does not affect the way the compiler handles RETVAL. + + bool_t + rpcb_gettime(host,timep) + char *host + time_t &timep + INIT: + printf("# Host is %s\n", host ); + OUTPUT: + timep =head2 The NO_INIT Keyword The NO_INIT keyword is used to indicate that a function -parameter is being used as only an output value. The B +parameter is being used only as an output value. The B compiler will normally generate code to read the values of all function parameters from the argument stack and assign them to C variables upon entry to the function. NO_INIT @@ -326,7 +344,7 @@ output rather than for input and that they will be handled before the function terminates. The following example shows a variation of the rpcb_gettime() function. -This function uses the timep variable as only an output variable and does +This function uses the timep variable only as an output variable and does not care about its initial contents. bool_t @@ -342,17 +360,19 @@ Function parameters are normally initialized with their values from the argument stack. The typemaps contain the code segments which are used to transfer the Perl values to the C parameters. The programmer, however, is allowed to -override the typemaps and supply alternate initialization -code. +override the typemaps and supply alternate (or additional) +initialization code. The following code demonstrates how to supply initialization code for -function parameters. The initialization code is eval'd by the compiler -before it is added to the output so anything which should be interpreted -literally, such as double quotes, must be protected with backslashes. +function parameters. The initialization code is eval'd within double +quotes by the compiler before it is added to the output so anything +which should be interpreted literally [mainly C<$>, C<@>, or C<\\>] +must be protected with backslashes. The variables C<$var>, C<$arg>, +and C<$type> can be used as in typemaps. bool_t rpcb_gettime(host,timep) - char *host = (char *)SvPV(ST(0),na); + char *host = (char *)SvPV($arg,PL_na); time_t &timep = 0; OUTPUT: timep @@ -362,6 +382,24 @@ would normally use this when a function parameter must be processed by another library function before it can be used. Default parameters are covered in the next section. +If the initialization begins with C<=>, then it is output on +the same line where the input variable is declared. If the +initialization begins with C<;> or C<+>, then it is output after +all of the input variables have been declared. The C<=> and C<;> +cases replace the initialization normally supplied from the typemap. +For the C<+> case, the initialization from the typemap will precede +the initialization code included after the C<+>. A global +variable, C<%v>, is available for the truly rare case where +information from one initialization is needed in another +initialization. + + bool_t + rpcb_gettime(host,timep) + time_t &timep ; /*\$v{time}=@{[$v{time}=$arg]}*/ + char *host + SvOK($v{time}) ? SvPV($arg,PL_na) : NULL; + OUTPUT: + timep + =head2 Default Parameter Values Default values can be specified for function parameters by @@ -393,6 +431,103 @@ the parameters in the correct order for that function. timep RETVAL +=head2 The PREINIT: Keyword + +The PREINIT: keyword allows extra variables to be declared before the +typemaps are expanded. If a variable is declared in a CODE: block then that +variable will follow any typemap code. This may result in a C syntax +error. To force the variable to be declared before the typemap code, place +it into a PREINIT: block. The PREINIT: keyword may be used one or more +times within an XSUB. + +The following examples are equivalent, but if the code is using complex +typemaps then the first example is safer. + + bool_t + rpcb_gettime(timep) + time_t timep = NO_INIT + PREINIT: + char *host = "localhost"; + CODE: + RETVAL = rpcb_gettime( host, &timep ); + OUTPUT: + timep + RETVAL + +A correct, but error-prone example. + + bool_t + rpcb_gettime(timep) + time_t timep = NO_INIT + CODE: + char *host = "localhost"; + RETVAL = rpcb_gettime( host, &timep ); + OUTPUT: + timep + RETVAL + +=head2 The SCOPE: Keyword + +The SCOPE: keyword allows scoping to be enabled for a particular XSUB. If +enabled, the XSUB will invoke ENTER and LEAVE automatically. + +To support potentially complex type mappings, if a typemap entry used +by this XSUB contains a comment like C then scoping will +automatically be enabled for that XSUB. + +To enable scoping: + + SCOPE: ENABLE + +To disable scoping: + + SCOPE: DISABLE + +=head2 The INPUT: Keyword + +The XSUB's parameters are usually evaluated immediately after entering the +XSUB. The INPUT: keyword can be used to force those parameters to be +evaluated a little later. The INPUT: keyword can be used multiple times +within an XSUB and can be used to list one or more input variables. This +keyword is used with the PREINIT: keyword. + +The following example shows how the input parameter C can be +evaluated late, after a PREINIT. + + bool_t + rpcb_gettime(host,timep) + char *host + PREINIT: + time_t tt; + INPUT: + time_t timep + CODE: + RETVAL = rpcb_gettime( host, &tt ); + timep = tt; + OUTPUT: + timep + RETVAL + +The next example shows each input parameter evaluated late. + + bool_t + rpcb_gettime(host,timep) + PREINIT: + time_t tt; + INPUT: + char *host + PREINIT: + char *h; + INPUT: + time_t timep + CODE: + h = host; + RETVAL = rpcb_gettime( h, &tt ); + timep = tt; + OUTPUT: + timep + RETVAL + =head2 Variable-length Parameter Lists XSUBs can have variable-length parameter lists by specifying an ellipsis @@ -416,18 +551,43 @@ The XS code, with ellipsis, follows. bool_t rpcb_gettime(timep, ...) time_t timep = NO_INIT - CODE: - { + PREINIT: char *host = "localhost"; - - if( items > 1 ) - host = (char *)SvPV(ST(1), na); - RETVAL = rpcb_gettime( host, &timep ); - } + STRLEN n_a; + CODE: + if( items > 1 ) + host = (char *)SvPV(ST(1), n_a); + RETVAL = rpcb_gettime( host, &timep ); OUTPUT: timep RETVAL +=head2 The C_ARGS: Keyword + +The C_ARGS: keyword allows creating of XSUBS which have different +calling sequence from Perl than from C, without a need to write +CODE: or CPPCODE: section. The contents of the C_ARGS: paragraph is +put as the argument to the called C function without any change. + +For example, suppose that C function is declared as + + symbolic nth_derivative(int n, symbolic function, int flags); + +and that the default flags are kept in a global C variable +C. Suppose that you want to create an interface which +is called as + + $second_deriv = $function->nth_derivative(2); + +To do this, declare the XSUB as + + symbolic + nth_derivative(function, n) + symbolic function + int n + C_ARGS: + n, function, default_flags + =head2 The PPCODE: Keyword The PPCODE: keyword is an alternate form of the CODE: keyword and is used @@ -445,15 +605,14 @@ Perl as a single list. void rpcb_gettime(host) char *host - PPCODE: - { + PREINIT: time_t timep; bool_t status; + PPCODE: status = rpcb_gettime( host, &timep ); - EXTEND(sp, 2); - PUSHs(sv_2mortal(newSVnv(status))); - PUSHs(sv_2mortal(newSVnv(timep))); - } + EXTEND(SP, 2); + PUSHs(sv_2mortal(newSViv(status))); + PUSHs(sv_2mortal(newSViv(timep))); Notice that the programmer must supply the C code necessary to have the real rpcb_gettime() function called and to have @@ -466,7 +625,7 @@ directive. The EXTEND() macro is used to make room on the argument stack for 2 return values. The PPCODE: directive causes the -B compiler to create a stack pointer called C, and it +B compiler to create a stack pointer available as C, and it is this pointer which is being used in the EXTEND() macro. The values are then pushed onto the stack with the PUSHs() macro. @@ -476,9 +635,12 @@ the following statement. ($status, $timep) = rpcb_gettime("localhost"); +When handling output parameters with a PPCODE section, be sure to handle +'set' magic properly. See L for details about 'set' magic. + =head2 Returning Undef And Empty Lists -Occasionally the programmer will want to simply return +Occasionally the programmer will want to return simply C or an empty list if a function fails rather than a separate status value. The rpcb_gettime() function offers just this situation. If the function succeeds we would like @@ -488,41 +650,39 @@ of $timep will either be undef or it will be a valid time. $timep = rpcb_gettime( "localhost" ); -The following XSUB uses the C return type to disable the generation of -the RETVAL variable and uses a CODE: block to indicate to the compiler +The following XSUB uses the C return type as a mnemonic only, +and uses a CODE: block to indicate to the compiler that the programmer has supplied all the necessary code. The sv_newmortal() call will initialize the return value to undef, making that the default return value. - void + SV * rpcb_gettime(host) char * host - CODE: - { + PREINIT: time_t timep; bool_t x; + CODE: ST(0) = sv_newmortal(); if( rpcb_gettime( host, &timep ) ) sv_setnv( ST(0), (double)timep); - } The next example demonstrates how one would place an explicit undef in the return value, should the need arise. - void + SV * rpcb_gettime(host) char * host - CODE: - { + PREINIT: time_t timep; bool_t x; + CODE: ST(0) = sv_newmortal(); if( rpcb_gettime( host, &timep ) ){ sv_setnv( ST(0), (double)timep); } else{ - ST(0) = &sv_undef; - } + ST(0) = &PL_sv_undef; } To return an empty list one must use a PPCODE: block and @@ -531,22 +691,27 @@ then not push return values on the stack. void rpcb_gettime(host) char *host - PPCODE: - { + PREINIT: time_t timep; + PPCODE: if( rpcb_gettime( host, &timep ) ) - PUSHs(sv_2mortal(newSVnv(timep))); + PUSHs(sv_2mortal(newSViv(timep))); else{ /* Nothing pushed on stack, so an empty */ /* list is implicitly returned. */ } - } + +Some people may be inclined to include an explicit C in the above +XSUB, rather than letting control fall through to the end. In those +situations C should be used, instead. This will ensure that +the XSUB stack is properly adjusted. Consult L for +other C macros. =head2 The REQUIRE: Keyword The REQUIRE: keyword is used to indicate the minimum version of the B compiler needed to compile the XS module. An XS module which -contains the following statement will only compile with B version +contains the following statement will compile with only B version 1.922 or greater: REQUIRE: 1.922 @@ -576,15 +741,289 @@ terminate the code block. # bootstrap function executes. printf("Hello from the bootstrap!\n"); +=head2 The VERSIONCHECK: Keyword + +The VERSIONCHECK: keyword corresponds to B's C<-versioncheck> and +C<-noversioncheck> options. This keyword overrides the command line +options. Version checking is enabled by default. When version checking is +enabled the XS module will attempt to verify that its version matches the +version of the PM module. + +To enable version checking: + + VERSIONCHECK: ENABLE + +To disable version checking: + + VERSIONCHECK: DISABLE + +=head2 The PROTOTYPES: Keyword + +The PROTOTYPES: keyword corresponds to B's C<-prototypes> and +C<-noprototypes> options. This keyword overrides the command line options. +Prototypes are enabled by default. When prototypes are enabled XSUBs will +be given Perl prototypes. This keyword may be used multiple times in an XS +module to enable and disable prototypes for different parts of the module. + +To enable prototypes: + + PROTOTYPES: ENABLE + +To disable prototypes: + + PROTOTYPES: DISABLE + +=head2 The PROTOTYPE: Keyword + +This keyword is similar to the PROTOTYPES: keyword above but can be used to +force B to use a specific prototype for the XSUB. This keyword +overrides all other prototype options and keywords but affects only the +current XSUB. Consult L for information about Perl +prototypes. + + bool_t + rpcb_gettime(timep, ...) + time_t timep = NO_INIT + PROTOTYPE: $;$ + PREINIT: + char *host = "localhost"; + STRLEN n_a; + CODE: + if( items > 1 ) + host = (char *)SvPV(ST(1), n_a); + RETVAL = rpcb_gettime( host, &timep ); + OUTPUT: + timep + RETVAL + +=head2 The ALIAS: Keyword + +The ALIAS: keyword allows an XSUB to have two or more unique Perl names +and to know which of those names was used when it was invoked. The Perl +names may be fully-qualified with package names. Each alias is given an +index. The compiler will setup a variable called C which contain the +index of the alias which was used. When the XSUB is called with its +declared name C will be 0. + +The following example will create aliases C and +C for this function. + + bool_t + rpcb_gettime(host,timep) + char *host + time_t &timep + ALIAS: + FOO::gettime = 1 + BAR::getit = 2 + INIT: + printf("# ix = %d\n", ix ); + OUTPUT: + timep + +=head2 The INTERFACE: Keyword + +This keyword declares the current XSUB as a keeper of the given +calling signature. If some text follows this keyword, it is +considered as a list of functions which have this signature, and +should be attached to XSUBs. + +Say, if you have 4 functions multiply(), divide(), add(), subtract() all +having the signature + + symbolic f(symbolic, symbolic); + +you code them all by using XSUB + + symbolic + interface_s_ss(arg1, arg2) + symbolic arg1 + symbolic arg2 + INTERFACE: + multiply divide + add subtract + +The advantage of this approach comparing to ALIAS: keyword is that one +can attach an extra function remainder() at runtime by using + + CV *mycv = newXSproto("Symbolic::remainder", + XS_Symbolic_interface_s_ss, __FILE__, "$$"); + XSINTERFACE_FUNC_SET(mycv, remainder); + +(This example supposes that there was no INTERFACE_MACRO: section, +otherwise one needs to use something else instead of +C.) + +=head2 The INTERFACE_MACRO: Keyword + +This keyword allows one to define an INTERFACE using a different way +to extract a function pointer from an XSUB. The text which follows +this keyword should give the name of macros which would extract/set a +function pointer. The extractor macro is given return type, C, +and C for this C. The setter macro is given cv, +and the function pointer. + +The default value is C and C. +An INTERFACE keyword with an empty list of functions can be omitted if +INTERFACE_MACRO keyword is used. + +Suppose that in the previous example functions pointers for +multiply(), divide(), add(), subtract() are kept in a global C array +C with offsets being C, C, C, +C. Then one can use + + #define XSINTERFACE_FUNC_BYOFFSET(ret,cv,f) \ + ((XSINTERFACE_CVT(ret,))fp[CvXSUBANY(cv).any_i32]) + #define XSINTERFACE_FUNC_BYOFFSET_set(cv,f) \ + CvXSUBANY(cv).any_i32 = CAT2( f, _off ) + +in C section, + + symbolic + interface_s_ss(arg1, arg2) + symbolic arg1 + symbolic arg2 + INTERFACE_MACRO: + XSINTERFACE_FUNC_BYOFFSET + XSINTERFACE_FUNC_BYOFFSET_set + INTERFACE: + multiply divide + add subtract + +in XSUB section. + +=head2 The INCLUDE: Keyword + +This keyword can be used to pull other files into the XS module. The other +files may have XS code. INCLUDE: can also be used to run a command to +generate the XS code to be pulled into the module. + +The file F contains our C function: + + bool_t + rpcb_gettime(host,timep) + char *host + time_t &timep + OUTPUT: + timep + +The XS module can use INCLUDE: to pull that file into it. + + INCLUDE: Rpcb1.xsh + +If the parameters to the INCLUDE: keyword are followed by a pipe (C<|>) then +the compiler will interpret the parameters as a command. + + INCLUDE: cat Rpcb1.xsh | + +=head2 The CASE: Keyword + +The CASE: keyword allows an XSUB to have multiple distinct parts with each +part acting as a virtual XSUB. CASE: is greedy and if it is used then all +other XS keywords must be contained within a CASE:. This means nothing may +precede the first CASE: in the XSUB and anything following the last CASE: is +included in that case. + +A CASE: might switch via a parameter of the XSUB, via the C ALIAS: +variable (see L<"The ALIAS: Keyword">), or maybe via the C variable +(see L<"Variable-length Parameter Lists">). The last CASE: becomes the +B case if it is not associated with a conditional. The following +example shows CASE switched via C with a function C +having an alias C. When the function is called as +C its parameters are the usual C<(char *host, time_t *timep)>, +but when the function is called as C its parameters are +reversed, C<(time_t *timep, char *host)>. + + long + rpcb_gettime(a,b) + CASE: ix == 1 + ALIAS: + x_gettime = 1 + INPUT: + # 'a' is timep, 'b' is host + char *b + time_t a = NO_INIT + CODE: + RETVAL = rpcb_gettime( b, &a ); + OUTPUT: + a + RETVAL + CASE: + # 'a' is host, 'b' is timep + char *a + time_t &b = NO_INIT + OUTPUT: + b + RETVAL + +That function can be called with either of the following statements. Note +the different argument lists. + + $status = rpcb_gettime( $host, $timep ); + + $status = x_gettime( $timep, $host ); + +=head2 The & Unary Operator + +The & unary operator is used to tell the compiler that it should dereference +the object when it calls the C function. This is used when a CODE: block is +not used and the object is a not a pointer type (the object is an C or +C but not a C or C). + +The following XSUB will generate incorrect C code. The xsubpp compiler will +turn this into code which calls C with parameters C<(char +*host, time_t timep)>, but the real C wants the C +parameter to be of type C rather than C. + + bool_t + rpcb_gettime(host,timep) + char *host + time_t timep + OUTPUT: + timep + +That problem is corrected by using the C<&> operator. The xsubpp compiler +will now turn this into code which calls C correctly with +parameters C<(char *host, time_t *timep)>. It does this by carrying the +C<&> through, so the function call looks like C. + + bool_t + rpcb_gettime(host,timep) + char *host + time_t &timep + OUTPUT: + timep + =head2 Inserting Comments and C Preprocessor Directives -Comments and C preprocessor directives are allowed within -CODE:, PPCODE:, BOOT:, and CLEANUP: blocks. The compiler -will pass the preprocessor directives through untouched and -will remove the commented lines. Comments can be added to -XSUBs by placing a C<#> at the beginning of the line. Care -should be taken to avoid making the comment look like a C -preprocessor directive, lest it be interpreted as such. +C preprocessor directives are allowed within BOOT:, PREINIT: INIT:, +CODE:, PPCODE:, and CLEANUP: blocks, as well as outside the functions. +Comments are allowed anywhere after the MODULE keyword. The compiler +will pass the preprocessor directives through untouched and will remove +the commented lines. + +Comments can be added to XSUBs by placing a C<#> as the first +non-whitespace of a line. Care should be taken to avoid making the +comment look like a C preprocessor directive, lest it be interpreted as +such. The simplest way to prevent this is to put whitespace in front of +the C<#>. + +If you use preprocessor directives to choose one of two +versions of a function, use + + #if ... version1 + #else /* ... version2 */ + #endif + +and not + + #if ... version1 + #endif + #if ... version2 + #endif + +because otherwise xsubpp will believe that you made a duplicate +definition of the function. Also, put a blank line before the +#else/#endif so it will not be seen as part of the function body. =head2 Using XS With C++ @@ -592,92 +1031,89 @@ If a function is defined as a C++ method then it will assume its first argument is an object pointer. The object pointer will be stored in a variable called THIS. The object should have been created by C++ with the new() function and should -be blessed by Perl with the sv_setptrobj() macro. The -blessing of the object by Perl can be handled by the -T_PTROBJ typemap. +be blessed by Perl with the sv_setref_pv() macro. The +blessing of the object by Perl can be handled by a typemap. An example +typemap is shown at the end of this section. If the method is defined as static it will call the C++ function using the class::method() syntax. If the method is not static -the function will be called using the THIS->method() syntax. +the function will be called using the THIS-Emethod() syntax. + +The next examples will use the following C++ class. + + class color { + public: + color(); + ~color(); + int blue(); + void set_blue( int ); + + private: + int c_blue; + }; -=head2 Perl Variables +The XSUBs for the blue() and set_blue() methods are defined with the class +name but the parameter for the object (THIS, or "self") is implicit and is +not listed. -The following demonstrates how the Perl variable $host can -be accessed from an XSUB. The function B is -used to obtain a pointer to the variable, known as an B -(Scalar Variable) internally. The package name C will be -added to the name of the variable so perl_get_sv() will know -in which package $host can be found. If the package name is -not supplied then perl_get_sv() will search package C
for -the variable. The macro B is then used to dereference -the SV to obtain a C pointer to its contents. + int + color::blue() void - rpcb_gettime() - PPCODE: - { - char *host; - SV *hostsv; - time_t timep; - - hostsv = perl_get_sv( "RPC::host", FALSE ); - if( hostsv != NULL ){ - host = SvPVX( hostsv ); - if( rpcb_gettime( host, &timep ) ) - PUSHs(sv_2mortal(newSVnv(timep))); - } - } + color::set_blue( val ) + int val -This Perl code can be used to call that XSUB. +Both functions will expect an object as the first parameter. The xsubpp +compiler will call that object C and will use it to call the specified +method. So in the C++ code the blue() and set_blue() methods will be called +in the following manner. - $RPC::host = "localhost"; - $timep = rpcb_gettime(); + RETVAL = THIS->blue(); -In the above example the SV contained a C C but a Perl -scalar variable may also contain numbers and references. If -the SV is expected to have a C C then the macro B -should be used to dereference the SV. When the SV contains -a C double then B should be used. + THIS->set_blue( val ); -The macro B can be used to dereference an SV when it is a Perl -reference. The result will be another SV which points to the actual Perl -variable. This can then be dereferenced with SvPVX(), SvNVX(), or -SvIVX(). The following XSUB will use SvRV(). +If the function's name is B then the C++ C function will be +called and C will be given as its parameter. void - rpcb_gettime() - PPCODE: - { - char *host; - SV *rv; - SV *hostsv; - time_t timep; - - rv = perl_get_sv( "RPC::host", FALSE ); - if( rv != NULL ){ - hostsv = SvRV( rv ); - host = SvPVX( hostsv ); - if( rpcb_gettime( host, &timep ) ) - PUSHs(sv_2mortal(newSVnv(timep))); - } - } + color::DESTROY() + +The C++ code will call C. + + delete THIS; -This Perl code will create a variable $RPC::host which is a -reference to $MY::host. The variable $MY::host contains the -hostname which will be used. +If the function's name is B then the C++ C function will be called +to create a dynamic C++ object. The XSUB will expect the class name, which +will be kept in a variable called C, to be given as the first +argument. - $MY::host = "localhost"; - $RPC::host = \$MY::host; - $timep = rpcb_gettime(); + color * + color::new() -The second argument to perl_get_sv() will normally be B -as shown in the above examples. An argument of B will -cause variables to be created if they do not already exist. -One should not use TRUE unless steps are taken to deal with -a possibly empty SV. +The C++ code will call C. -XSUBs may use B, B, and B to -access Perl arrays, hashes, and code values. + RETVAL = new color(); + +The following is an example of a typemap that could be used for this C++ +example. + + TYPEMAP + color * O_OBJECT + + OUTPUT + # The Perl object is blessed into 'CLASS', which should be a + # char* having the name of the package for the blessing. + O_OBJECT + sv_setref_pv( $arg, CLASS, (void*)$var ); + + INPUT + O_OBJECT + if( sv_isobject($arg) && (SvTYPE(SvRV($arg)) == SVt_PVMG) ) + $var = ($type)SvIV((SV*)SvRV( $arg )); + else{ + warn( \"${Package}::$func_name() -- $var is not a blessed SV reference\" ); + XSRETURN_UNDEF; + } =head2 Interface Strategy @@ -707,41 +1143,6 @@ cases it may be helpful to use the T_PTROBJ typemap for these structures so they can be manipulated by Perl as blessed objects. -=head2 The Perl Module - -The Perl module is the link between the extension library, -which was generated from XS code, and the Perl interpreter. -The module is used to tell Perl what the extension library -contains. The name and package of the module should match -the name of the library. - -The following is a Perl module for an extension containing -some ONC+ RPC bind library functions. - - package RPC; - - require Exporter; - require DynaLoader; - @ISA = qw(Exporter DynaLoader); - @EXPORT = qw( rpcb_gettime rpcb_getmaps rpcb_getaddr - rpcb_rmtcall rpcb_set rpcb_unset ); - - bootstrap RPC; - 1; - -The RPC extension contains the functions found in the -@EXPORT list. By using the C module the RPC module -can make these function names visible to the rest of the -Perl program. The C module will allow the RPC -module to bootstrap the extension library. To load this -extension and make the functions available, the following -Perl statement should be used. - - use RPC; - -For more information about the DynaLoader consult its documentation in the -ext/DynaLoader directory in the Perl source. - =head2 Perl Objects And C Structures When dealing with C structures one should select either @@ -808,88 +1209,20 @@ does not care, that this object is a C struct and not a Perl object. In this sense, there is no difference between the object created by the getnetconfigent() XSUB and an object created by a normal Perl subroutine. -=head2 C Headers and Perl - -The B compiler is designed to convert C header files in -/usr/include into Perl extensions. This compiler will -create a directory under the C directory of the Perl -source and will populate it with a Makefile, a Perl Module, -an XS source file, and a MANIFEST file. - -The following command will create an extension called C -from the header. - - h2xs rpcsvc/rusers - -When the Rusers extension has been compiled and installed -Perl can use it to retrieve any C<#define> statements which -were in the C header. - - use Rusers; - print "RPC program number for rusers service: "; - print &RUSERSPROG, "\n"; - -=head2 Creating A New Extension - -The B compiler can generate template source files and -Makefiles. These templates offer a suitable starting point -for most extensions. The following example demonstrates how -one might use B to create an extension containing the RPC -functions in this document. - -The extension will not use autoloaded functions and will not define -constants, so the B<-A> option will be given to B. When run from the -Perl source directory, the B compiler will create the directory -ext/RPC and will populate it with files called RPC.xs, RPC.pm, Makefile.PL, -and MANIFEST. The XS code for the RPC functions should be added to the -RPC.xs file. The @EXPORT list in RPC.pm should be updated to include the -functions from RPC.xs. - - h2xs -An RPC - -To compile the extension for dynamic loading the following -command should be executed from the ext/RPC directory. - - make dynamic - -If the extension will be statically linked into the Perl -binary then the makefile (use C, not C) in the -Perl source directory should be edited to add C -to the C variable. Before making this change Perl -should have already been built. After the makefile has been -updated the following command should be executed from the -Perl source directory. - - make - -Perl's B script can also be used to add extensions. The extension -should be placed in the C directory under the Perl source before Perl -has been built and prior to running Configure. When Configure is run it -will find the extension along with the other extensions in the C -directory and will add it to the list of extensions to be built. When make -is run the extension will be built along with the other extensions. - -Configure recognizes extensions if they have an XS source -file which matches the name of the extension directory. If -the extension directory includes a MANIFEST file Configure -will search that file for any B<.SH> files and extract them -after it extracts all the other .SH files listed in the main -MANIFEST. The main Perl Makefile will then run B in the -extension's directory if it finds an XS file matching the -name of the extension's directory. - =head2 The Typemap The typemap is a collection of code fragments which are used by the B compiler to map C function parameters and values to Perl values. The typemap file may consist of three sections labeled C, C, and -C. The INPUT section tells the compiler how to translate Perl values +C. Any unlabelled initial section is assumed to be a C +section if a name is not explicitly specified. The INPUT section tells +the compiler how to translate Perl values into variables of certain C types. The OUTPUT section tells the compiler how to translate the values from certain C types into values Perl can understand. The TYPEMAP section tells the compiler which of the INPUT and OUTPUT code fragments should be used to map a given C type to a Perl value. -Each of the sections of the typemap must be preceded by one of the TYPEMAP, -INPUT, or OUTPUT keywords. +The section labels C, C, or C must begin +in the first column on a line by themselves, and must be in uppercase. The default typemap in the C directory of the Perl source contains many useful types which can be used by Perl extensions. Some extensions define @@ -909,6 +1242,37 @@ that the C unary operator C<*> is considered to be a part of the C type name. TYPEMAP Netconfig *T_PTROBJ +Here's a more complicated example: suppose that you wanted C to be blessed into the class C. One way to do +this is to use underscores (_) to separate package names, as follows: + + typedef struct netconfig * Net_Config; + +And then provide a typemap entry C that maps underscores to +double-colons (::), and declare C to be of that type: + + + TYPEMAP + Net_Config T_PTROBJ_SPECIAL + + INPUT + T_PTROBJ_SPECIAL + if (sv_derived_from($arg, \"${(my $ntt=$ntype)=~s/_/::/g;\$ntt}\")) { + IV tmp = SvIV((SV*)SvRV($arg)); + $var = ($type) tmp; + } + else + croak(\"$var is not of type ${(my $ntt=$ntype)=~s/_/::/g;\$ntt}\") + + OUTPUT + T_PTROBJ_SPECIAL + sv_setref_pv($arg, \"${(my $ntt=$ntype)=~s/_/::/g;\$ntt}\", + (void*)$var); + +The INPUT and OUTPUT sections substitute underscores for double-colons +on the fly, giving the desired effect. This example demonstrates some +of the power and versatility of the typemap facility. + =head1 EXAMPLES File C: Interface to some ONC+ RPC bind library functions. @@ -923,16 +1287,15 @@ File C: Interface to some ONC+ RPC bind library functions. MODULE = RPC PACKAGE = RPC - void + SV * rpcb_gettime(host="localhost") char *host - CODE: - { + PREINIT: time_t timep; + CODE: ST(0) = sv_newmortal(); if( rpcb_gettime( host, &timep ) ) sv_setnv( ST(0), (double)timep ); - } Netconfig * getnetconfigent(netid="udp") @@ -979,7 +1342,11 @@ File C: Perl test program for the RPC extension. print "netconf = $netconf\n"; +=head1 XS VERSION + +This document covers features supported by C 1.935. + =head1 AUTHOR -Dean Roehrich Froehrich@cray.comE> -Oct 12, 1995 +Dean Roehrich > +Jul 8, 1996