| perlintern - autogenerated documentation of purely B<internal> Perl functions |
| perlintern - autogenerated documentation of purely internal | |
| Perl functions |
This file is the autogenerated documentation of functions in the Perl interpreter that are documented using Perl's internal documentation format but are not marked as part of the Perl API. In other words, they are not for use in extensions!
CvOUTSIDE(), to its lexically enclosing
CV (if any). Because pointers to anonymous sub prototypes are
stored in & pad slots, it is a possible to get a circular reference,
with the parent pointing to the child and vice-versa. To avoid the
ensuing memory leak, we do not increment the reference count of the CV
pointed to by CvOUTSIDE in the one specific instance that the parent
has a & pad slot pointing back to us. In this case, we set the
CvWEAKOUTSIDE flag in the child. This allows us to determine under what
circumstances we should decrement the refcount of the parent when freeing
the child.
There is a further complication with non-closure anonymous subs (ie those that do not refer to any lexicals outside that sub). In this case, the anonymous prototype is shared rather than being cloned. This has the consequence that the parent may be freed while there are still active children, eg
BEGIN { $a = sub { eval '$x' } }
In this case, the BEGIN is freed immediately after execution since there
are no active references to it: the anon sub prototype has
CvWEAKOUTSIDE set since it's not a closure, and $a points to the same
CV, so it doesn't contribute to BEGIN's refcount either. When $a is
executed, the eval '$x' causes the chain of CvOUTSIDEs to be followed,
and the freed BEGIN is accessed.
To avoid this, whenever a CV and its associated pad is freed, any
& entries in the pad are explicitly removed from the pad, and if the
refcount of the pointed-to anon sub is still positive, then that
child's CvOUTSIDE is set to point to its grandparent. This will only
occur in the single specific case of a non-closure anon prototype
having one or more active references (such as $a above).
One other thing to consider is that a CV may be merely undefined
rather than freed, eg undef &foo. In this case, its refcount may
not have reached zero, but we still delete its pad and its CvROOT etc.
Since various children may still have their CvOUTSIDE pointing at this
undefined CV, we keep its own CvOUTSIDE for the time being, so that
the chain of lexical scopes is unbroken. For example, the following
should print 123:
my $x = 123;
sub tmp { sub { eval '$x' } }
my $a = tmp();
undef &tmp;
print $a->();
bool CvWEAKOUTSIDE(CV *cv)
void CX_CURPAD_SAVE(struct context)
SV * CX_CURPAD_SV(struct context, PADOFFSET po)
po in the base (DEPTH=1) pad of a padlist
SV * PAD_BASE_SV (PADLIST padlist, PADOFFSET po)
void PAD_CLONE_VARS(PerlInterpreter *proto_perl \)
po. Assumes a valid slot entry.
U32 PAD_COMPNAME_FLAGS(PADOFFSET po)
po in the current
compiling pad (lvalue). Note that SvCUR is hijacked for this purpose.
STRLEN PAD_COMPNAME_GEN(PADOFFSET po)
our variable.
Assumes the slot entry is a valid our lexical.
HV * PAD_COMPNAME_OURSTASH(PADOFFSET po)
po. Assumes a valid slot entry.
char * PAD_COMPNAME_PV(PADOFFSET po)
po. Must be a valid name. Returns null if not typed.
HV * PAD_COMPNAME_TYPE(PADOFFSET po)
void PAD_DUP(PADLIST dstpad, PADLIST srcpad, CLONE_PARAMS* param)
PAD_SAVE_LOCAL()
void PAD_RESTORE_LOCAL(PAD *opad)
void PAD_SAVE_LOCAL(PAD *opad, PAD *npad)
void PAD_SAVE_SETNULLPAD()
po in the current pad to sv
SV * PAD_SETSV (PADOFFSET po, SV* sv)
n in the padlist, saving
the previous current pad.
void PAD_SET_CUR (PADLIST padlist, I32 n)
void PAD_SET_CUR_NOSAVE (PADLIST padlist, I32 n)
po in the current pad
void PAD_SV (PADOFFSET po)
PAD_SV.
Get or set the value at offset po in the current pad.
Unlike PAD_SV, does not print diagnostics with -DX.
For internal use only.
SV * PAD_SVl (PADOFFSET po)
void SAVECLEARSV (SV **svp)
void SAVECOMPPAD()
| XXX DAPM it would make more sense to make the arg a PADOFFSET | |||
| void | SAVEPADSV | (PADOFFSET po) |
CV* find_runcv(U32 *db_seqp)
PL_DBsub.
SV * PL_DBsingle
PL_DBsingle.
GV * PL_DBsub
PL_DBsingle.
SV * PL_DBtrace
bool PL_dowarn
<FH>)
GV* PL_last_in_gv
$, in Perl space.
SV* PL_ofs_sv
$/ in Perl space.
SV* PL_rs
TRUE if given the name of a magical GV.
Currently only useful internally when determining if a GV should be created even in rvalue contexts.
flags is not used at present but available for future extension to
allow selecting particular classes of magical variable.
bool is_gv_magical(char *name, STRLEN len, U32 flags)
do_readline to spawn a glob (or do the glob inside
perl on VMS). This code used to be inline, but now perl uses File::Glob
this glob starter is only used by miniperl during the build process.
Moving it away shrinks pp_hot.c; shrinking pp_hot.c helps speed perl up.
PerlIO* start_glob(SV* pattern, IO *io)
CvPADLIST(cv) set to point to an AV.
For these purposes ``forms'' are a kind-of CV, eval``''s are too (except they're not callable at will and are always thrown away after the eval``'' is done executing).
XSUBs don't have CvPADLIST set - dXSTARG fetches values from PL_curpad, but that is really the callers pad (a slot of which is allocated by every entersub).
The CvPADLIST AV has does not have AvREAL set, so REFCNT of component items is managed ``manual'' (mostly in pad.c) rather than normal av.c rules. The items in the AV are not SVs as for a normal AV, but other AVs:
0'th Entry of the CvPADLIST is an AV which represents the ``names'' or rather the ``static type information'' for lexicals.
The CvDEPTH'th entry of CvPADLIST AV is an AV which is the stack frame at that depth of recursion into the CV. The 0'th slot of a frame AV is an AV which is @_. other entries are storage for variables and op targets.
During compilation:
PL_comppad_name is set to the names AV.
PL_comppad is set to the frame AV for the frame CvDEPTH == 1.
PL_curpad is set to the body of the frame AV (i.e. AvARRAY(PL_comppad)).
During execution, PL_comppad and PL_curpad refer to the live
frame of the currently executing sub.
Iterating over the names AV iterates over all possible pad items. Pad slots that are SVs_PADTMP (targets/GVs/constants) end up having &PL_sv_undef ``names'' (see pad_alloc()).
Only my/our variable (SVs_PADMY/SVs_PADOUR) slots get valid names. The rest are op targets/GVs/constants which are statically allocated or resolved at compile time. These don't have names by which they can be looked up from Perl code at run time through eval``'' like my/our variables can be. Since they can't be looked up by ``name'' but only by their index allocated at compile time (which is usually in PL_op->op_targ), wasting a name SV for them doesn't make sense.
The SVs in the names AV have their PV being the name of the variable.
NV+1..IV inclusive is a range of cop_seq numbers for which the name is
valid. For typed lexicals name SV is SVt_PVMG and SvSTASH points at the
type. For our lexicals, the type is SVt_PVGV, and GvSTASH points at the
stash of the associated global (so that duplicate our delarations in the
same package can be detected). SvCUR is sometimes hijacked to
store the generation number during compilation.
If SvFAKE is set on the name SV then slot in the frame AVs are a REFCNT'ed references to a lexical from ``outside''. In this case, the name SV does not have a cop_seq range, since it is in scope throughout.
If the 'name' is '&' the corresponding entry in frame AV
is a CV representing a possible closure.
(SvFAKE and name of '&' is not a meaningful combination currently but could
become so if my sub foo {} is implemented.)
AV * CvPADLIST(CV *cv)
CV* cv_clone(CV* proto)
void cv_dump(CV *cv, char *title)
void do_dump_pad(I32 level, PerlIO *file, PADLIST *padlist, int full)
U32 intro_my()
PADOFFSET pad_add_anon(SV* sv, OPCODE op_type)
typestash is valid, the name is for a typed lexical; set the
name's stash to that value.
If ourstash is valid, it's an our lexical, set the name's
GvSTASH to that value
Also, if the name is @.. or %.., create a new array or hash for that slot
If fake, it means we're cloning an existing entry
PADOFFSET pad_add_name(char *name, HV* typestash, HV* ourstash, bool clone)
PADOFFSET pad_alloc(I32 optype, U32 tmptype)
void pad_block_start(int full)
ourstash
is_our indicates that the name to check is an 'our' declaration
void pad_check_dup(char* name, bool is_our, HV* ourstash)
PADOFFSET pad_findlex(char* name, PADOFFSET newoff, CV* innercv)
PADOFFSET pad_findmy(char* name)
void pad_fixup_inner_anons(PADLIST *padlist, CV *old_cv, CV *new_cv)
void pad_free(PADOFFSET po)
void pad_leavemy()
padnew_CLONE this pad is for a cloned CV
padnew_SAVE save old globals
padnew_SAVESUB also save extra stuff for start of sub
PADLIST* pad_new(int flags)
void pad_push(PADLIST *padlist, int depth, int has_args)
void pad_reset()
PAD_SETSV() rather than calling this function directly.
void pad_setsv(PADOFFSET po, SV* sv)
void pad_swipe(PADOFFSET po, bool refadjust)
void pad_tidy(padtidy_type type)
(This function should really be called pad_free, but the name was already taken)
void pad_undef(CV* cv)
SP. This is actually identical to dSP, and declares
a local copy of perl's stack pointer, available via the SP macro.
See SP. (Available for backward source code compatibility with the
old (Perl 5.005) thread model.)
djSP;
void report_uninit()
void sv_add_arena(char* ptr, U32 size, U32 flags)
I32 sv_clean_all()
void sv_clean_objs()
void sv_free_arenas()
The autodocumentation system was originally added to the Perl core by Benjamin Stuhl. Documentation is by whoever was kind enough to document their functions.
perlguts(1), perlapi(1)
| perlintern - autogenerated documentation of purely B<internal> Perl functions |