Re: Ref to a list not being equivalent to a list of refs to each element

A related quirk I ran across earlier, and which I also am not sure is documented (though I may have missed it), is that references to literal strings are read-only, but references to computed strings, including interpolated literals, are not. For example

my $x = 'foo';
my $y = \"bar$x";
$$x = 'baz';
[download]

does not throw any errors or warnings. Does anyone know why exactly that is?

Comment on Re: Ref to a list not being equivalent to a list of refs to each element Download Code

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Re^2: Ref to a list not being equivalent to a list of refs to each element by broquaint (Abbot) on Jun 23, 2006 at 17:26 UTC
This occurs for the same reasons given above as `\"foo";` [download] creates a references to a constant value whereas `\"foo$x";` [download] is creating a reference to a temporary value. If you want to see the evidence then just put `Devel::Peek` to work (take note of the `FLAGS` values for the reference): `use Devel::Peek; my $x = 'foo'; Dump \'foo'; Dump \"bar$x"; __output__ SV = RV(0x183c90c) at 0x225fe4 REFCNT = 1 FLAGS = (PADBUSY,PADTMP,ROK,READONLY) RV = 0x225ffc SV = PV(0x22626c) at 0x225ffc REFCNT = 1 FLAGS = (POK,READONLY,pPOK) PV = 0x1831d04 "foo"\0 CUR = 3 LEN = 4 SV = RV(0x183c92c) at 0x2252ac REFCNT = 1 FLAGS = (TEMP,ROK) RV = 0x225150 SV = PV(0x2261a0) at 0x225150 REFCNT = 1 FLAGS = (POK,pPOK) PV = 0x1831cac "barfoo"\0 CUR = 6 LEN = 7` [download] HTH `_________ broquaint`	[reply] [d/l] [select]

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Re^2: Ref to a list not being equivalent to a list of refs to each element
by broquaint (Abbot) on Jun 23, 2006 at 17:26 UTC

\"foo";
[download]

\"foo$x";
[download]

If you want to see the evidence then just put Devel::Peek to work (take note of the FLAGS values for the reference):

use Devel::Peek;

my $x = 'foo';

Dump \'foo';
Dump \"bar$x";

__output__
SV = RV(0x183c90c) at 0x225fe4         
  REFCNT = 1                           
  FLAGS = (PADBUSY,PADTMP,ROK,READONLY)
  RV = 0x225ffc                        
  SV = PV(0x22626c) at 0x225ffc        
    REFCNT = 1                         
    FLAGS = (POK,READONLY,pPOK)        
    PV = 0x1831d04 "foo"\0             
    CUR = 3                            
    LEN = 4                            
SV = RV(0x183c92c) at 0x2252ac         
  REFCNT = 1                           
  FLAGS = (TEMP,ROK)                   
  RV = 0x225150                        
  SV = PV(0x2261a0) at 0x225150        
    REFCNT = 1                         
    FLAGS = (POK,pPOK)                 
    PV = 0x1831cac "barfoo"\0          
    CUR = 6                            
    LEN = 7
[download]

HTH

_________ broquaint

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