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NAMEExtUtils::Constant - generate XS code to import C header constants
use ExtUtils::Constant qw (WriteConstants); WriteConstants( NAME => 'Foo', NAMES => [qw(FOO BAR BAZ)], ); # Generates wrapper code to make the values of the constants FOO BAR BAZ # available to perl
DESCRIPTIONExtUtils::Constant facilitates generating C and
USAGEGenerally one only needs to call the "WriteConstants" function, and then
in the C section of "Foo.xs"
For greater flexibility use "constant_types()", "C_constant" and "XS_constant", with which "WriteConstants" is implemented.
Currently this module understands the following types. h2xs may only know a subset. The sizes of the numeric types are chosen by the "Configure" script at compile time.
- signed integer, at least 32 bits.
unsigned integer, the same size as IV
- floating point type, probably "double", possibly "long double"
NULterminated string, length will be determined with "strlen"
A fixed length thing, given as a [pointer, length] pair. If you know the
length of a string at compile time you may use this instead of PV
A mortal SV.
- Truth. ("PL_sv_yes") The value is not needed (and ignored).
- Defined Falsehood. ("PL_sv_no") The value is not needed (and ignored).
- "undef". The value of the macro is not needed.
A function returning a single scalar with "#define" definitions for the
constants used internally between the generated C and XSfunctions.
- XS_constant PACKAGE, TYPES, XS_SUBNAME, C_SUBNAME
A function to generate the XScode to implement the perl subroutinePACKAGE::constant used byPACKAGE::AUTOLOAD to load constants. ThisXScode is a wrapper around a C subroutine usually generated by "C_constant", and usually named "constant".TYPESshould be given either as a comma separated list of types that the C subroutine "constant" will generate or as a reference to a hash. It should be the same list of types as "C_constant" was given. [Otherwise "XS_constant" and "C_constant" may have different ideas about the number of parameters passed to the C function "constant"]
You can call the perl visible subroutine something other than "constant" if you give the parameterXS_SUBNAME. The C subroutine it calls defaults to the name of the perl visible subroutine, unless you give the parameter C_SUBNAME.
- autoload PACKAGE, VERSION, AUTOLOADER
A function to generate the AUTOLOADsubroutine for the modulePACKAGEVERSIONis the perl version the code should be backwards compatible with. It defaults to the version of perl running the subroutine. IfAUTOLOADERis true, theAUTOLOADsubroutine falls back on AutoLoader::AUTOLOAD for all names that the constant() routine doesn't recognise.
WriteMakefileSnippet ATTRIBUTE=>VALUE[, ...]
A function to generate perl code for Makefile.PL that will regenerate the constant subroutines. Parameters are named as passed to "WriteConstants", with the addition of "INDENT" to specify the number of leading spaces (default 2).
Currently only "INDENT", "NAME", "DEFAULT_TYPE", "NAMES", "C_FILE" and "XS_FILE" are recognised.
- WriteConstants ATTRIBUTE=>VALUE[, ...]
Writes a file of C code and a file of XScode which you should "#include" and "INCLUDE" in the C andXSsections respectively of your module'sXScode. You probably want to do this in your "Makefile.PL", so that you can easily edit the list of constants without touching the rest of your module. The attributes supported are
- Name of the module. This must be specified
- The default type for the constants. If not specified "IV" is assumed.
- The names of the constants are grouped by length. Generate child subroutines for each group with this number or more names in.
- An array of constants' names, either scalars containing names, or hashrefs as detailed in ``C_constant''.
- If true, uses proxy subs. See ExtUtils::Constant::ProxySubs.
- A filehandle to write the C code to. If not given, then C_FILE is opened for writing.
- The name of the file to write containing the C code. The default is "const-c.inc". The "-" in the name ensures that the file can't be mistaken for anything related to a legitimate perl package name, and not naming the file ".c" avoids having to override Makefile.PL's ".xs" to ".c" rules.
A filehandle to write the XScode to. If not given, thenXS_FILEis opened for writing.
The name of the file to write containing the XScode. The default is "const-xs.inc".
The perl visible name of the XSsubroutine generated which will return the constants. The default is "constant".
The name of the C subroutine generated which will return the constants.
The default is XS_SUBNAME. Child subroutines have "_" and the name length appended, so constants with 10 character names would be in "constant_10" with the defaultXS_SUBNAME.