H2XS(1)          Perl Programmers Reference Guide         H2XS(1)


NAME
       h2xs - convert .h C header files to Perl extensions



SYNOPSIS
       h2xs [-AOPXcdf] [-v version] [-n module_name] [-p prefix]
       [-s sub] [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 require AutoLoader statement
            from the .pm file.

       -F   Additional flags to specify to C preprocessor when
            scanning header for function declarations. Should not
            be used without -x.

       -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   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 /usr/include.



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       -h   Print the usage, help and version for this h2xs and
            exit.

       -n module_name
            Specifies a name to be used for the extension, e.g.,
            -n RPC::DCE

       -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()
            mechansim.

       -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.

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 <rpcsvc/rusers.h>
               h2xs rpcsvc::rusers

               # Extension is ONC::RPC.  Still finds <rpcsvc/rusers.h>
               h2xs -n ONC::RPC rpcsvc/rusers





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H2XS(1)          Perl Programmers Reference Guide         H2XS(1)


               # 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 "sec_rgy_" is dropped from perl function names
               h2xs -n DCE::rgynbase -p sec_rgy_ dce/rgynbase

               # Extension is DCE::rgynbase
               # prefix "sec_rgy_" is dropped from perl function names
               # subroutines are created for sec_rgy_wildcard_name and sec_rgy_wildcard_sid
               h2xs -n DCE::rgynbase -p sec_rgy_ \
               -s sec_rgy_wildcard_name,sec_rgy_wildcard_sid dce/rgynbase

               # 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 "-DEXT=extern -DdEXT= -DINIT\(x\)=" perl.h

               # Same with function declaration in proto.h as visible from perl.h.
               h2xs -xAn perl2 perl.h,proto.h


ENVIRONMENT
       No environment variables are used.

AUTHOR
       Larry Wall and others

SEE ALSO
       the perl manpage, the perlxstut manpage, the
       ExtUtils::MakeMaker manpage, and the AutoLoader manpage.

DIAGNOSTICS
       The usual warnings if it cannot read or write the files
       involved.









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