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H2XS !!!H2XS NAME SYNOPSIS DESCRIPTION OPTIONS EXAMPLES ENVIRONMENT AUTHOR SEE ALSO DIAGNOSTICS LIMITATIONS of -x ---- !!NAME h2xs - convert .h C header files to Perl extensions !!SYNOPSIS __h2xs__ [[__-ACOPXacdfkmx__] [[__-F__ addflags] [[__-M__ fmask] [[__-n__ module_name] [[__-o__ tmask] [[__-p__ prefix] [[__-s__ subs] [[__-v__ version] [[headerfile ... [[extra_libraries]] __h2xs -h__ !!DESCRIPTION ''h2xs'' builds a Perl extension from C header files. The extension will include functions which can be used to retrieve the value of any #define statement which was in the C header files. The ''module_name'' will be used for the name of the extension. If module_name is not supplied then the name of the first header file will be used, with the first character capitalized. If the extension might need extra libraries, they should be included here. The extension Makefile.PL will take care of checking whether the libraries actually exist and how they should be loaded. The extra libraries should be specified in the form -lm -lposix, etc, just as on the cc command line. By default, the Makefile.PL will search through the library path determined by Configure. That path can be augmented by including arguments of the form __-L/another/library/path__ in the extra-libraries argument. !!OPTIONS __-A__ Omit all autoload facilities. This is the same as __-c__ but also removes the use !AutoLoader statement from the .pm file. __-C__ Omits creation of the ''Changes'' file, and adds a HISTORY section to the POD template. __-F__ ''addflags'' Additional flags to specify to C preprocessor when scanning header for function declarations. Should not be used without __-x__. __-M__ ''regular expression'' selects functions/macros to process. __-O__ Allows a pre-existing extension directory to be overwritten. __-P__ Omit the autogenerated stub POD section. __-X__ Omit the XS portion. Used to generate templates for a module which is not XS-based. -c and -f are implicitly enabled. __-a__ Generate an accessor method for each element of structs and unions. The generated methods are named after the element name; will return the current value of the element if called without additional arguments; and will set the element to the supplied value (and return the new value) if called with an additional argument. Embedded structures and unions are returned as a pointer rather than the complete structure, to facilitate chained calls. These methods all apply to the Ptr type for the structure; additionally two methods are constructed for the structure type itself, _to_ptr which returns a Ptr type pointing to the same structure, and a new method to construct and return a new structure, initialised to zeroes. __-c__ Omit constant() from the .xs file and corresponding specialised AUTOLOAD from the .pm file. __-d__ Turn on debugging messages. __-f__ Allows an extension to be created for a header even if that header is not found in standard include directories. __-h__ Print the usage, help and version for this h2xs and exit. __-k__ For function arguments declared as const, omit the const attribute in the generated XS code. __-m__ __Experimental__: for each variable declared in the header file(s), declare a perl variable of the same name magically tied to the C variable. __-n__ ''module_name'' Specifies a name to be used for the extension, e.g., -n RPC::DCE __-o__ ''regular expression'' Use ``opaque'' data type for the C types matched by the regular expression, even if these types are typedef-equivalent to types from typemaps. Should not be used without __-x__. This may be useful since, say, types which are typedef-equivalent to integers may represent OS-related handles, and one may want to work with these handles in OO-way, as in $handle-. Use -o . if you want to handle all the typedefed types as opaque types. The type-to-match is whitewashed (except for commas, which have no whitespace before them, and multiple * which have no whitespace between them). __-p__ ''prefix'' Specify a prefix which should be removed from the Perl function names, e.g., -p sec_rgy_ This sets up the XS __PREFIX__ keyword and removes the prefix from functions that are autoloaded via the constant() mechanism. __-s__ ''sub1,sub2'' Create a perl subroutine for the specified macros rather than autoload with the ''constant()'' subroutine. These macros are assumed to have a return type of __char *__, e.g., -s sec_rgy_wildcard_name,sec_rgy_wildcard_sid. __-v__ ''version'' Specify a version number for this extension. This version number is added to the templates. The default is 0.01. __-x__ Automatically generate XSUBs basing on function declarations in the header file. The package C::Scan should be installed. If this option is specified, the name of the header file may look like NAME1,NAME2. In this case NAME1 is used instead of the specified string, but XSUBs are emitted only for the declarations included from file NAME2 . Note that some types of arguments/return-values for functions may result in XSUB-declarations/typemap-entries which need hand-editing. Such may be objects which cannot be converted from/to a pointer (like long long), pointers to functions, or arrays. See also the section on LIMITATIONS of __-x____ __-b__ ''version'' Generates a .pm file which is backwards compatible with the specified perl version. For versions Specifying a compatibility version higher than the version of perl you are using to run h2xs will have no effect. !!EXAMPLES # Default behavior, extension is Rusers h2xs rpcsvc/rusers # Same, but extension is RUSERS h2xs -n RUSERS rpcsvc/rusers # Extension is rpcsvc::rusers. Still finds # Extension is ONC::RPC. Still finds # Without constant() or AUTOLOAD h2xs -c rpcsvc/rusers # Creates templates for an extension named RPC h2xs -cfn RPC # Extension is ONC::RPC. h2xs -cfn ONC::RPC # Makefile.PL will look for library -lrpc in # additional directory /opt/net/lib h2xs rpcsvc/rusers -L/opt/net/lib -lrpc # Extension is DCE::rgynbase # prefix # Extension is DCE::rgynbase # prefix # Make XS without defines in perl.h, but with function declarations # visible from perl.h. Name of the extension is perl1. # When scanning perl.h, define -DEXT=extern -DdEXT= -DINIT(x)= # Extra backslashes below because the string is passed to shell. # Note that a directory with perl header files would # be added automatically to include path. h2xs -xAn perl1 -F # Same with function declaration in proto.h as visible from perl.h. h2xs -xAn perl2 perl.h,proto.h # Same but select only functions which match /^av_/ h2xs -M '^av_' -xAn perl2 perl.h,proto.h # Same but treat SV* etc as __Extension based on__ ''.h'' __and__ ''.c'' __files__ Suppose that you have some C files implementing some functionality, and the corresponding header files. How to create an extension which makes this functionality accessable in Perl? The example below assumes that the header files are ''interface_simple.h'' and ''interface_hairy.h'', and you want the perl module be named as Ext::Ension. If you need some preprocessor directives and/or linking with external libraries, see the flags -F, -L and -l in `` OPTIONS ''. Find the directory name Start with a dummy run of h2xs: h2xs -Afn Ext::Ension The only purpose of this step is to create the needed directories, and let you know the names of these directories. From the output you can see that the directory for the extension is ''Ext/Ension''. Copy C files Copy your header files and C files to this directory ''Ext/Ension''. Create the extension Run h2xs, overwriting older autogenerated files: h2xs -Oxan Ext::Ension interface_simple.h interface_hairy.h h2xs looks for header files ''after'' changing to the extension directory, so it will find your header files OK . Archive and test As usual, run cd Ext/Ension perl Makefile.PL make dist make make test Hints It is important to do make dist as early as possible. This way you can easily merge(1) your changes to autogenerated files if you decide to edit your .h files and rerun h2xs. Do not forget to edit the documentation in the generated ''.pm'' file. Consider the autogenerated files as skeletons only, you may invent better interfaces than what h2xs could guess. Consider this section as a guideline only, some other options of h2xs may better suit your needs. !!ENVIRONMENT No environment variables are used. !!AUTHOR Larry Wall and others !!SEE ALSO perl, perlxstut, !ExtUtils::!MakeMaker, and !AutoLoader. !!DIAGNOSTICS The usual warnings if it cannot read or write the files involved. !!LIMITATIONS of -x ''h2xs'' would not distinguish whether an argument to a C function which is of the form, say, int *, is an input, output, or input/output parameter. In particular, argument declarations of the form int foo(n) int *n should be better rewritten as int foo(n) int if n is an input parameter. Additionally, ''h2xs'' has no facilities to intuit that a function int foo(addr,l) char *addr int l takes a pair of address and length of data at this address, so it is better to rewrite this function as int foo(sv) SV *addr PREINIT: STRLEN len; char *s; CODE: s = SvPV(sv,len); RETVAL = foo(s, len); OUTPUT: RETVAL or alternately static int my_foo(SV *sv) { STRLEN len; char *s = SvPV(sv,len); return foo(s, len); } MODULE = foo PACKAGE = foo PREFIX = my_ int foo(sv) SV *sv See perlxs and perlxstut for additional details. ----
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