X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/70a53b35304cccc28c78bbda3a5e80f421d5a8a0..e69061dc352aead76c31e0d932d915ea7ce26512:/pod/perlguts.pod

diff --git a/pod/perlguts.pod b/pod/perlguts.pod
index 00df255..d8f0527 100644
--- a/pod/perlguts.pod
+++ b/pod/perlguts.pod
@@ -619,41 +619,45 @@ L<Stashes and Globs> for information on converting class names into stashes.
 
 /* Still under construction */
 
-Upgrades rv to reference if not already one.  Creates new SV for rv to
-point to.  If C<classname> is non-null, the SV is blessed into the specified
-class.  SV is returned.
+The following function upgrades rv to reference if not already one.
+Creates a new SV for rv to point to.  If C<classname> is non-null, the SV
+is blessed into the specified class.  SV is returned.
 
 	SV* newSVrv(SV* rv, const char* classname);
 
-Copies integer, unsigned integer or double into an SV whose reference is C<rv>.  SV is blessed
-if C<classname> is non-null.
+The following three functions copy integer, unsigned integer or double
+into an SV whose reference is C<rv>.  SV is blessed if C<classname> is
+non-null.
 
 	SV* sv_setref_iv(SV* rv, const char* classname, IV iv);
 	SV* sv_setref_uv(SV* rv, const char* classname, UV uv);
 	SV* sv_setref_nv(SV* rv, const char* classname, NV iv);
 
-Copies the pointer value (I<the address, not the string!>) into an SV whose
-reference is rv.  SV is blessed if C<classname> is non-null.
+The following function copies the pointer value (I<the address, not the
+string!>) into an SV whose reference is rv.  SV is blessed if C<classname>
+is non-null.
 
-	SV* sv_setref_pv(SV* rv, const char* classname, PV iv);
+	SV* sv_setref_pv(SV* rv, const char* classname, void* pv);
 
-Copies string into an SV whose reference is C<rv>.  Set length to 0 to let
-Perl calculate the string length.  SV is blessed if C<classname> is non-null.
+The following function copies string into an SV whose reference is C<rv>.
+Set length to 0 to let Perl calculate the string length.  SV is blessed if
+C<classname> is non-null.
 
-	SV* sv_setref_pvn(SV* rv, const char* classname, PV iv, STRLEN length);
+	SV* sv_setref_pvn(SV* rv, const char* classname, char* pv, STRLEN length);
 
-Tests whether the SV is blessed into the specified class.  It does not
-check inheritance relationships.
+The following function tests whether the SV is blessed into the specified
+class.  It does not check inheritance relationships.
 
 	int  sv_isa(SV* sv, const char* name);
 
-Tests whether the SV is a reference to a blessed object.
+The following function tests whether the SV is a reference to a blessed object.
 
 	int  sv_isobject(SV* sv);
 
-Tests whether the SV is derived from the specified class. SV can be either
-a reference to a blessed object or a string containing a class name. This
-is the function implementing the C<UNIVERSAL::isa> functionality.
+The following function tests whether the SV is derived from the specified
+class. SV can be either a reference to a blessed object or a string
+containing a class name. This is the function implementing the
+C<UNIVERSAL::isa> functionality.
 
 	bool sv_derived_from(SV* sv, const char* name);
 
@@ -671,11 +675,11 @@ your Perl script, use the following routines, depending on the variable type.
     AV*  get_av("package::varname", GV_ADD);
     HV*  get_hv("package::varname", GV_ADD);
 
-Notice the use of TRUE as the second parameter.  The new variable can now
+Notice the use of GV_ADD as the second parameter.  The new variable can now
 be set, using the routines appropriate to the data type.
 
 There are additional macros whose values may be bitwise OR'ed with the
-C<TRUE> argument to enable certain extra features.  Those bits are:
+C<GV_ADD> argument to enable certain extra features.  Those bits are:
 
 =over
 
@@ -963,6 +967,12 @@ To remove the magic from an SV, call the function sv_unmagic:
 The C<type> argument should be equal to the C<how> value when the C<SV>
 was initially made magical.
 
+However, note that C<sv_unmagic> removes all magic of a certain C<type> from the
+C<SV>. If you want to remove only certain magic of a C<type> based on the magic
+virtual table, use C<sv_unmagicext> instead:
+
+    int sv_unmagicext(SV *sv, int type, MGVTBL *vtbl);
+
 =head2 Magic Virtual Tables
 
 The C<mg_virtual> field in the C<MAGIC> structure is a pointer to an
@@ -1025,19 +1035,28 @@ The current kinds of Magic Virtual Tables are:
     (old-style char and macro)   MGVTBL          Type of magic
     --------------------------   ------          -------------
     \0 PERL_MAGIC_sv             vtbl_sv         Special scalar variable
+    #  PERL_MAGIC_arylen         vtbl_arylen     Array length ($#ary)
+    %  PERL_MAGIC_rhash          (none)          extra data for restricted
+                                                 hashes
+    .  PERL_MAGIC_pos            vtbl_pos        pos() lvalue
+    :  PERL_MAGIC_symtab         (none)          extra data for symbol tables
+    <  PERL_MAGIC_backref        vtbl_backref    for weak ref data
+    @  PERL_MAGIC_arylen_p       (none)          to move arylen out of XPVAV
     A  PERL_MAGIC_overload       vtbl_amagic     %OVERLOAD hash
     a  PERL_MAGIC_overload_elem  vtbl_amagicelem %OVERLOAD hash element
-    c  PERL_MAGIC_overload_table (none)          Holds overload table (AMT)
-                                                 on stash
-    B  PERL_MAGIC_bm             vtbl_bm         Boyer-Moore (fast string search)
-    D  PERL_MAGIC_regdata        vtbl_regdata    Regex match position data
+    B  PERL_MAGIC_bm             vtbl_regexp     Boyer-Moore 
+                                                 (fast string search)
+    c  PERL_MAGIC_overload_table vtbl_ovrld      Holds overload table 
+                                                 (AMT) on stash
+    D  PERL_MAGIC_regdata        vtbl_regdata    Regex match position data 
                                                  (@+ and @- vars)
     d  PERL_MAGIC_regdatum       vtbl_regdatum   Regex match position data
                                                  element
     E  PERL_MAGIC_env            vtbl_env        %ENV hash
     e  PERL_MAGIC_envelem        vtbl_envelem    %ENV hash element
-    f  PERL_MAGIC_fm             vtbl_fm         Formline ('compiled' format)
-    g  PERL_MAGIC_regex_global   vtbl_mglob      m//g target / study()ed string
+    f  PERL_MAGIC_fm             vtbl_regdata    Formline ('compiled' format)
+    G  PERL_MAGIC_study          vtbl_regdata    study()ed string
+    g  PERL_MAGIC_regex_global   vtbl_mglob      m//g target
     H  PERL_MAGIC_hints          vtbl_hints      %^H hash
     h  PERL_MAGIC_hintselem      vtbl_hintselem  %^H hash element
     I  PERL_MAGIC_isa            vtbl_isa        @ISA array
@@ -1045,29 +1064,28 @@ The current kinds of Magic Virtual Tables are:
     k  PERL_MAGIC_nkeys          vtbl_nkeys      scalar(keys()) lvalue
     L  PERL_MAGIC_dbfile         (none)          Debugger %_<filename
     l  PERL_MAGIC_dbline         vtbl_dbline     Debugger %_<filename element
-    o  PERL_MAGIC_collxfrm       vtbl_collxfrm   Locale collate transformation
+    N  PERL_MAGIC_shared         (none)          Shared between threads
+    n  PERL_MAGIC_shared_scalar  (none)          Shared between threads
+    o  PERL_MAGIC_collxfrm       vtbl_collxfrm   Locale transformation
     P  PERL_MAGIC_tied           vtbl_pack       Tied array or hash
     p  PERL_MAGIC_tiedelem       vtbl_packelem   Tied array or hash element
     q  PERL_MAGIC_tiedscalar     vtbl_packelem   Tied scalar or handle
-    r  PERL_MAGIC_qr             vtbl_qr         precompiled qr// regex
-    S  PERL_MAGIC_sig            vtbl_sig        %SIG hash
+    r  PERL_MAGIC_qr             vtbl_regexp     precompiled qr// regex
+    S  PERL_MAGIC_sig            (none)          %SIG hash
     s  PERL_MAGIC_sigelem        vtbl_sigelem    %SIG hash element
     t  PERL_MAGIC_taint          vtbl_taint      Taintedness
     U  PERL_MAGIC_uvar           vtbl_uvar       Available for use by extensions
+    u  PERL_MAGIC_uvar_elem      (none)          Reserved for use by extensions
+    V  PERL_MAGIC_vstring        (none)          SV was vstring literal
     v  PERL_MAGIC_vec            vtbl_vec        vec() lvalue
-    V  PERL_MAGIC_vstring        (none)          v-string scalars
-    w  PERL_MAGIC_utf8           vtbl_utf8       UTF-8 length+offset cache
+    w  PERL_MAGIC_utf8           vtbl_utf8       Cached UTF-8 information
     x  PERL_MAGIC_substr         vtbl_substr     substr() lvalue
     y  PERL_MAGIC_defelem        vtbl_defelem    Shadow "foreach" iterator
                                                  variable / smart parameter
                                                  vivification
-    #  PERL_MAGIC_arylen         vtbl_arylen     Array length ($#ary)
-    .  PERL_MAGIC_pos            vtbl_pos        pos() lvalue
-    <  PERL_MAGIC_backref        vtbl_backref    back pointer to a weak ref 
+    ]  PERL_MAGIC_checkcall      (none)          inlining/mutation of call to
+                                                 this CV
     ~  PERL_MAGIC_ext            (none)          Available for use by extensions
-    :  PERL_MAGIC_symtab         (none)          hash used as symbol table
-    %  PERL_MAGIC_rhash          (none)          hash used as restricted hash
-    @  PERL_MAGIC_arylen_p       vtbl_arylen_p   pointer to $#a from @a
 
 
 When an uppercase and lowercase letter both exist in the table, then the
@@ -1119,7 +1137,7 @@ is activated whenever the hash is accessed with a key specified as
 an C<SV> through the functions C<hv_store_ent>, C<hv_fetch_ent>,
 C<hv_delete_ent>, and C<hv_exists_ent>.  Accessing the key as a string
 through the functions without the C<..._ent> suffix circumvents the
-hook.  See L<Hash::Util::Fieldhash/Guts> for a detailed description.
+hook.  See L<Hash::Util::FieldHash/GUTS> for a detailed description.
 
 Note that because multiple extensions may be using C<PERL_MAGIC_ext>
 or C<PERL_MAGIC_uvar> magic, it is important for extensions to take
@@ -1128,16 +1146,16 @@ objects blessed into the same class as the extension is sufficient.
 For C<PERL_MAGIC_ext> magic, it is usually a good idea to define an
 C<MGVTBL>, even if all its fields will be C<0>, so that individual
 C<MAGIC> pointers can be identified as a particular kind of magic
-using their C<mg_virtual> field.
+using their magic virtual table. C<mg_findext> provides an easy way
+to do that:
 
     STATIC MGVTBL my_vtbl = { 0, 0, 0, 0, 0, 0, 0, 0 };
 
     MAGIC *mg;
-    for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
-        if (mg->mg_type == PERL_MAGIC_ext && mg->mg_virtual == &my_vtbl) {
-            /* this is really ours, not another module's PERL_MAGIC_ext */
-            my_priv_data_t *priv = (my_priv_data_t *)mg->mg_ptr;
-        }
+    if ((mg = mg_findext(sv, PERL_MAGIC_ext, &my_vtbl))) {
+        /* this is really ours, not another module's PERL_MAGIC_ext */
+        my_priv_data_t *priv = (my_priv_data_t *)mg->mg_ptr;
+        ...
     }
 
 Also note that the C<sv_set*()> and C<sv_cat*()> functions described
@@ -1154,11 +1172,18 @@ since their implementation handles 'get' magic.
 
 =head2 Finding Magic
 
-    MAGIC* mg_find(SV*, int type); /* Finds the magic pointer of that type */
+    MAGIC *mg_find(SV *sv, int type); /* Finds the magic pointer of that type */
+
+This routine returns a pointer to a C<MAGIC> structure stored in the SV.
+If the SV does not have that magical feature, C<NULL> is returned. If the
+SV has multiple instances of that magical feature, the first one will be
+returned. C<mg_findext> can be used to find a C<MAGIC> structure of an SV
+based on both it's magic type and it's magic virtual table:
+
+    MAGIC *mg_findext(SV *sv, int type, MGVTBL *vtbl);
 
-This routine returns a pointer to the C<MAGIC> structure stored in the SV.
-If the SV does not have that magical feature, C<NULL> is returned.  Also,
-if the SV is not of type SVt_PVMG, Perl may core dump.
+Also, if the SV passed to C<mg_find> or C<mg_findext> is not of type
+SVt_PVMG, Perl may core dump.
 
     int mg_copy(SV* sv, SV* nsv, const char* key, STRLEN klen);
 
@@ -1450,6 +1475,8 @@ L</Reference Counts and Mortality>):
     PUSHs(sv_2mortal(newSVuv(an_unsigned_integer)))
     PUSHs(sv_2mortal(newSVnv(a_double)))
     PUSHs(sv_2mortal(newSVpv("Some String",0)))
+    /* Although the last example is better written as the more efficient: */
+    PUSHs(newSVpvs_flags("Some String", SVs_TEMP))
 
 And now the Perl program calling C<tzname>, the two values will be assigned
 as in:
@@ -2346,7 +2373,7 @@ usually called within the sources as C<whatever(...)>.
 
 This does not need a interpreter context, so the definition has no
 C<pTHX>, and it follows that callers don't use C<aTHX>.  (See
-L<perlguts/Background and PERL_IMPLICIT_CONTEXT>.)
+L</Background and PERL_IMPLICIT_CONTEXT>.)
 
 =item r