Internals(3pm)

1Internals(3pm)         Perl Programmers Reference Guide         Internals(3pm)
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NAME

6       Internals - Reserved special namespace for internals related functions
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SYNOPSIS

9           $is_ro= Internals::SvREADONLY($x)
10           $refcnt= Internals::SvREFCNT($x)
11           hv_clear_placeholders(%hash);
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DESCRIPTION

14       The Internals namespace is used by the core Perl development team to
15       expose certain low level internals routines for testing and other
16       purposes.
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18       In theory these routines were not and are not intended to be used
19       outside of the perl core, and are subject to change and removal at any
20       time.
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22       In practice people have come to depend on these over the years, despite
23       being historically undocumented, so we will provide some level of
24       forward compatibility for some time. Nevertheless you can assume that
25       any routine documented here is experimental or deprecated and you
26       should find alternatives to their use.
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28   FUNCTIONS
29       SvREFCNT(THING [, $value])
30           Historically Perl has been a refcounted language. This means that
31           each variable tracks how many things reference it, and when the
32           variable is no longer referenced it will automatically free itself.
33           In theory Perl code should not have to care about this, and in a
34           future version Perl might change to some other strategy, although
35           in practice this is unlikely.
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37           This function allows one to violate the abstraction of variables
38           and get or set the refcount of a variable, and in generally is
39           really only useful in code that is testing refcount behavior.
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41           *NOTE* You are strongly discouraged from using this function in
42           non-test code and especially discouraged from using the set form of
43           this function.  The results of doing so may result in segmentation
44           faults or other undefined behavior.
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46       SvREADONLY(THING, [, $value])
47           Set or get whether a variable is readonly or not. Exactly what the
48           readonly flag means depend on the type of the variable affected and
49           the version of perl used.
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51           You are strongly discouraged from using this function directly. It
52           is used by various core modules, like "Hash::Util", and the
53           "constant" pragma to implement higher-level behavior which should
54           be used instead.
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56           See the core implementation for the exact meaning of the readonly
57           flag for each internal variable type.
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59       hv_clear_placeholders(%hash)
60           Clear any placeholders from a locked hash. Should not be used
61           directly.  You should use the wrapper functions providewd by
62           Hash::Util instead.  As of 5.25 also available as "
63           Hash::Util::_clear_placeholders(%hash) "
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AUTHOR

66       Perl core development team.
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NAME

SYNOPSIS

DESCRIPTION

AUTHOR

SEE ALSO