Throw a helpful warning when someone tries length(@array) or length(%hash)

[perl5.git] / perlvars.h

/*    perlvars.h
 *
 *    Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
 *    by Larry Wall and others
 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 */

/*
=head1 Global Variables
*/

/* Don't forget to re-run regen/embed.pl to propagate changes! */

/* This file describes the "global" variables used by perl
 * This used to be in perl.h directly but we want to abstract out into
 * distinct files which are per-thread, per-interpreter or really global,
 * and how they're initialized.
 *
 * The 'G' prefix is only needed for vars that need appropriate #defines
 * generated in embed*.h.  Such symbols are also used to generate
 * the appropriate export list for win32. */

/* global state */
#if defined(USE_ITHREADS)
PERLVAR(G, op_mutex,	perl_mutex)	/* Mutex for op refcounting */
#endif
PERLVAR(G, curinterp,	PerlInterpreter *)
					/* currently running interpreter
					 * (initial parent interpreter under
					 * useithreads) */
#if defined(USE_ITHREADS)
PERLVAR(G, thr_key,	perl_key)	/* key to retrieve per-thread struct */
#endif

/* XXX does anyone even use this? */
PERLVARI(G, do_undump,	bool,	FALSE)	/* -u or dump seen? */

#ifndef PERL_USE_SAFE_PUTENV
PERLVARI(G, use_safe_putenv, bool, TRUE)
#endif

#if defined(FAKE_PERSISTENT_SIGNAL_HANDLERS)||defined(FAKE_DEFAULT_SIGNAL_HANDLERS)
PERLVARI(G, sig_handlers_initted, int, 0)
#endif
#ifdef FAKE_PERSISTENT_SIGNAL_HANDLERS
PERLVARA(G, sig_ignoring, SIG_SIZE, int)
					/* which signals we are ignoring */
#endif
#ifdef FAKE_DEFAULT_SIGNAL_HANDLERS
PERLVARA(G, sig_defaulting, SIG_SIZE, int)
#endif

/* XXX signals are process-wide anyway, so we
 * ignore the implications of this for threading */
#ifndef HAS_SIGACTION
PERLVARI(G, sig_trapped, int,	0)
#endif

#ifndef PERL_MICRO
/* If Perl has to ignore SIGPFE, this is its saved state.
 * See perl.h macros PERL_FPU_INIT and PERL_FPU_{PRE,POST}_EXEC. */
PERLVAR(G, sigfpe_saved, Sighandler_t)
PERLVARI(G, csighandlerp, Sighandler_t, Perl_csighandler)
					/* Pointer to C-level sighandler */
#endif

/* This is constant on most architectures, a global on OS/2 */
#ifdef OS2
PERLVARI(G, sh_path,	char *, SH_PATH) /* full path of shell */
#endif

#ifdef USE_PERLIO

#  if defined(USE_ITHREADS)
PERLVAR(G, perlio_mutex, perl_mutex)    /* Mutex for perlio fd refcounts */
#  endif

PERLVARI(G, perlio_fd_refcnt, int *, 0) /* Pointer to array of fd refcounts.  */
PERLVARI(G, perlio_fd_refcnt_size, int, 0) /* Size of the array */
PERLVARI(G, perlio_debug_fd, int, 0)	/* the fd to write perlio debug into, 0 means not set yet */
#endif

#ifdef HAS_MMAP
PERLVARI(G, mmap_page_size, IV, 0)
#endif

#if defined(USE_ITHREADS)
PERLVAR(G, hints_mutex, perl_mutex)    /* Mutex for refcounted he refcounting */
#endif

#ifdef DEBUGGING
PERLVAR(G, watch_pvx,	char *)
#endif

#ifdef PERL_GLOBAL_STRUCT 
PERLVAR(G, ppaddr,	Perl_ppaddr_t *) /* or opcode.h */
PERLVAR(G, check,	Perl_check_t *) /* or opcode.h */
PERLVARA(G, fold_locale, 256, unsigned char) /* or perl.h */
#endif

#ifdef PERL_NEED_APPCTX
PERLVAR(G, appctx,	void*)		/* the application context */
#endif

#if defined(HAS_TIMES) && defined(PERL_NEED_TIMESBASE)
PERLVAR(G, timesbase,	struct tms)
#endif

/* allocate a unique index to every module that calls MY_CXT_INIT */

#ifdef PERL_IMPLICIT_CONTEXT
# ifdef USE_ITHREADS
PERLVAR(G, my_ctx_mutex, perl_mutex)
# endif
PERLVARI(G, my_cxt_index, int,	0)
#endif

/* this is currently set without MUTEX protection, so keep it a type which
 * can be set atomically (ie not a bit field) */
PERLVARI(G, veto_cleanup, int, FALSE)	/* exit without cleanup */

/*
=for apidoc AmUx|Perl_keyword_plugin_t|PL_keyword_plugin

Function pointer, pointing at a function used to handle extended keywords.
The function should be declared as

	int keyword_plugin_function(pTHX_
		char *keyword_ptr, STRLEN keyword_len,
		OP **op_ptr)

The function is called from the tokeniser, whenever a possible keyword
is seen.  C<keyword_ptr> points at the word in the parser's input
buffer, and C<keyword_len> gives its length; it is not null-terminated.
The function is expected to examine the word, and possibly other state
such as L<%^H|perlvar/%^H>, to decide whether it wants to handle it
as an extended keyword.  If it does not, the function should return
C<KEYWORD_PLUGIN_DECLINE>, and the normal parser process will continue.

If the function wants to handle the keyword, it first must
parse anything following the keyword that is part of the syntax
introduced by the keyword.  See L</Lexer interface> for details.

When a keyword is being handled, the plugin function must build
a tree of C<OP> structures, representing the code that was parsed.
The root of the tree must be stored in C<*op_ptr>.  The function then
returns a constant indicating the syntactic role of the construct that
it has parsed: C<KEYWORD_PLUGIN_STMT> if it is a complete statement, or
C<KEYWORD_PLUGIN_EXPR> if it is an expression.  Note that a statement
construct cannot be used inside an expression (except via C<do BLOCK>
and similar), and an expression is not a complete statement (it requires
at least a terminating semicolon).

When a keyword is handled, the plugin function may also have
(compile-time) side effects.  It may modify C<%^H>, define functions, and
so on.  Typically, if side effects are the main purpose of a handler,
it does not wish to generate any ops to be included in the normal
compilation.  In this case it is still required to supply an op tree,
but it suffices to generate a single null op.

That's how the C<*PL_keyword_plugin> function needs to behave overall.
Conventionally, however, one does not completely replace the existing
handler function.  Instead, take a copy of C<PL_keyword_plugin> before
assigning your own function pointer to it.  Your handler function should
look for keywords that it is interested in and handle those.  Where it
is not interested, it should call the saved plugin function, passing on
the arguments it received.  Thus C<PL_keyword_plugin> actually points
at a chain of handler functions, all of which have an opportunity to
handle keywords, and only the last function in the chain (built into
the Perl core) will normally return C<KEYWORD_PLUGIN_DECLINE>.

=cut
*/

PERLVARI(G, keyword_plugin, Perl_keyword_plugin_t, Perl_keyword_plugin_standard)

PERLVAR(G, op_sequence, HV *)		/* dump.c */
PERLVARI(G, op_seq,	UV,	0)	/* dump.c */

#ifdef USE_ITHREADS
PERLVAR(G, dollarzero_mutex, perl_mutex) /* Modifying $0 */
#endif

/* Restricted hashes placeholder value.
 * The contents are never used, only the address. */
PERLVAR(G, sv_placeholder, SV)

#if defined(MYMALLOC) && defined(USE_ITHREADS)
PERLVAR(G, malloc_mutex, perl_mutex)	/* Mutex for malloc */
#endif