comment on

I don't see any difference with or without weaken $wrapper;,what's it there for?

Where exactly?

How are you checking to see a difference?

$ perl -MDevel::Peek -MScalar::Util=weaken -le " sub fudge { my $f = s
+ub { print 1; }; Dump($f); weaken $f; Dump($f); $f; } $f = fudge(); $
+f->(); Dump($f);"
SV = IV(0x3f8d18) at 0x3f8d1c
  REFCNT = 1
  FLAGS = (PADMY,ROK)
  RV = 0x3f8cfc
  SV = PVCV(0x9a263c) at 0x3f8cfc
    REFCNT = 2
    FLAGS = (PADSTALE,PADMY,ANON,WEAKOUTSIDE,CVGV_RC)
    COMP_STASH = 0x3f8b5c       "main"
    START = 0x9d9178 ===> 0
    ROOT = 0x9d913c
    GVGV::GV = 0x99a9f4 "main" :: "__ANON__"
    FILE = "-e"
    DEPTH = 0
    FLAGS = 0x490
    OUTSIDE_SEQ = 272
    PADLIST = 0x99aa24
    PADNAME = 0x99aae4(0x9a7d1c) PAD = 0x3f8d0c(0x9a7b44)
    OUTSIDE = 0x99aa74 (fudge)
SV = IV(0x3f8d18) at 0x3f8d1c
  REFCNT = 1
  FLAGS = (PADMY,ROK,WEAKREF)
  RV = 0x3f8cfc
  SV = PVCV(0x9a263c) at 0x3f8cfc
    REFCNT = 1
    FLAGS = (PADSTALE,PADMY,RMG,ANON,WEAKOUTSIDE,CVGV_RC)
    MAGIC = 0x3fff2c
      MG_VIRTUAL = &PL_vtbl_backref
      MG_TYPE = PERL_MAGIC_backref(<)
      MG_OBJ = 0x3f8d1c
    COMP_STASH = 0x3f8b5c       "main"
    START = 0x9d9178 ===> 0
    ROOT = 0x9d913c
    GVGV::GV = 0x99a9f4 "main" :: "__ANON__"
    FILE = "-e"
    DEPTH = 0
    FLAGS = 0x490
    OUTSIDE_SEQ = 272
    PADLIST = 0x99aa24
    PADNAME = 0x99aae4(0x9a7d1c) PAD = 0x3f8d0c(0x9a7b44)
    OUTSIDE = 0x99aa74 (fudge)
1
SV = IV(0x9c2e40) at 0x9c2e44
  REFCNT = 1
  FLAGS = (ROK)
  RV = 0x3f8cfc
  SV = PVCV(0x9a263c) at 0x3f8cfc
    REFCNT = 2
    FLAGS = (PADSTALE,PADMY,RMG,ANON,WEAKOUTSIDE,CVGV_RC)
    MAGIC = 0x3fff2c
      MG_VIRTUAL = &PL_vtbl_backref
      MG_TYPE = PERL_MAGIC_backref(<)
    COMP_STASH = 0x3f8b5c       "main"
    START = 0x9d9178 ===> 0
    ROOT = 0x9d913c
    GVGV::GV = 0x99a9f4 "main" :: "__ANON__"
    FILE = "-e"
    DEPTH = 0
    FLAGS = 0x490
    OUTSIDE_SEQ = 272
    PADLIST = 0x99aa24
    PADNAME = 0x99aae4(0x9a7d1c) PAD = 0x3f8d0c(0x9a7b44)
    OUTSIDE = 0x99aa74 (fudge)
[download]

As you notice, REFCNT doesn't change :)

Yeah, that is not a use case for weaken, you use weaken when you have circular references, say

my $foo = { kid  => { } };
$foo->{kid}{parent} = $foo;
weaken $foo->{kid}{parent};
[download]

In reply to Re: What's the weaken here for? by Anonymous Monk
in thread What's the weaken here for? by PerlOnTheWay

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