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Diffstat (limited to 'Master/tlpkg/tlperl/lib/Internals.pod')
-rwxr-xr-x | Master/tlpkg/tlperl/lib/Internals.pod | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/Master/tlpkg/tlperl/lib/Internals.pod b/Master/tlpkg/tlperl/lib/Internals.pod new file mode 100755 index 00000000000..4a1144afd6d --- /dev/null +++ b/Master/tlpkg/tlperl/lib/Internals.pod @@ -0,0 +1,78 @@ +=head1 NAME + +Internals - Reserved special namespace for internals related functions + +=head1 SYNOPSIS + + $is_ro= Internals::SvREADONLY($x) + $refcnt= Internals::SvREFCNT($x) + hv_clear_placeholders(%hash); + +=head1 DESCRIPTION + +The Internals namespace is used by the core Perl development team to +expose certain low level internals routines for testing and other purposes. + +In theory these routines were not and are not intended to be used outside +of the perl core, and are subject to change and removal at any time. + +In practice people have come to depend on these over the years, despite +being historically undocumented, so we will provide some level of +forward compatibility for some time. Nevertheless you can assume that any +routine documented here is experimental or deprecated and you should find +alternatives to their use. + +=head2 FUNCTIONS + +=over 4 + +=item SvREFCNT(THING [, $value]) + +Historically Perl has been a refcounted language. This means that each +variable tracks how many things reference it, and when the variable is no +longer referenced it will automatically free itself. In theory Perl code +should not have to care about this, and in a future version Perl might +change to some other strategy, although in practice this is unlikely. + +This function allows one to violate the abstraction of variables and get +or set the refcount of a variable, and in generally is really only useful +in code that is testing refcount behavior. + +*NOTE* You are strongly discouraged from using this function in non-test +code and especially discouraged from using the set form of this function. +The results of doing so may result in segmentation faults or other undefined +behavior. + +=item SvREADONLY(THING, [, $value]) + +Set or get whether a variable is readonly or not. Exactly what the +readonly flag means depend on the type of the variable affected and the +version of perl used. + +You are strongly discouraged from using this function directly. It is used +by various core modules, like C<Hash::Util>, and the C<constant> pragma +to implement higher-level behavior which should be used instead. + +See the core implementation for the exact meaning of the readonly flag for +each internal variable type. + +=item hv_clear_placeholders(%hash) + +Clear any placeholders from a locked hash. Should not be used directly. +You should use the wrapper functions providewd by Hash::Util instead. +As of 5.25 also available as C< Hash::Util::_clear_placeholders(%hash) > + +=back + +=head1 AUTHOR + +Perl core development team. + +=head1 SEE ALSO + +L<perlguts> +L<Hash::Util> +L<constant> +universal.c + +=cut |