ExtUtils::Constant::ProxySubs - generate XS ProxySubs code
use ExtUtils::Constant qw (WriteConstants);
WriteConstants(
NAME => 'Package',
NAMES => [qw(FOO BAR BAZ)],
PROXYSUBS => { autoload => 1 },
DEFAULT_TYPE => 'IV',
);
# Generates easier wrapper code, unusable with 5.6With the PROXYSUBS option to WriteConstants, this module generates better XS code, with 4 optional variants.
Each symbol is added as CONSTSUB at BOOT time, as via sub NAME () {value}. Undefined names (#undef NAME) will be stored in a special ExtUtils::Constant::ProxySubs::Missing namespace, because accessing an undefined name should throw a different error "Your vendor has not defined MyPackage macro NAME", and not "Undefined subroutine &MyPackage::NAME".
There's no run-time lookup for matching names in the constant function, but there's still AUTOLOAD needed to catch unknown names and a short dispatch for matching types.
NOTICE:
ExtUtils::Constant::ProxySubs versions older than 0.23_04 creates code usable only >= 5.14. There is no official CPAN version which creates usable code yet. The CPAN maintainers think p5p should sort it out, which they didn't for the last 7 years.
PROXYSUBS can be used with an optional hashref of 4 exclusive options.
'autoload', 'croak_on_error' and 'croak_on_read' can not be used together. 'push' and 'croak_on_read' cannot be used together.
This option generates an XS AUTOLOAD function which dispatches to the XS constant function. Only auto-generated C and XS code is needed, no manual addition of sub AUTOLOAD as generated by ExtUtils::Constant::autoload.
Limitation: With 5.6 the error message for undefined macros is not "Your vendor has not defined MyPackage macro NAME", but "Undefined subroutine &MyPackage::NAME"
This option keeps a list of all added constants.
E.g. NAME => 'MyPackage', PROXYSUBS => { push => 'CONSTNAMES' }, will create @MyPackage::CONSTNAMES.
Errors in run-time name lookup via XS constant is normally handled by AUTOLOAD. With croak_on_error the AUTOLOAD function can be simplified, errors with missing undefined names are thrown directly in the XS constant() function.
The XS caller context might be different to the pure-perl AUTOLOAD context though, identifying the source location of the error.
Similar to croak_on_error, but much more restrictive. For each variable which should report the "Your vendor has not defined MyPackage macro NAME" error, a magic getter and setter hook is added to throw this error.
This option creates code usable only since Perl 5.24, so don't use it with any CPAN module!
Reini Urban <rurban@cpan.org> fixed up ProxySubs and took over maintainance. Nicholas Clark <nick@ccl4.org> wrote it from scratch.