Hi

the primitive idea behind local is that the current value is pushed to a stack and is restored when the scope finishes. 

 
{ 
  push @stack,$scalar;
  $scalar=undef;
 
  ... some code...
 
  $scalar=shift @stack;
}

[download]

But it's not that easy to simulate local for lexicals, if the var is actually tied.

Consider this example which works very well for package-vars WITHOUT interfering with tie:

package NewStdScalar;
require Tie::Scalar;
 
@ISA = qw(Tie::StdScalar);
 
sub FETCH { return ${+shift}++ }
 
package main;
 
tie our $scalar, 'NewStdScalar';
 
$scalar=0;
 
print $scalar;             # 0
 
{
  local $scalar="---";     # ---
  print $scalar;
}
   
print $scalar;             # 1

[download]

So is it possible to get this behavior for lexicals even if they are tied?

I'd like to implement this just with CORE-moduls, so PadWalker is not an option.

Cheers Rolf

PS: While I'm writing this I'm getting an idea how to achieve this ... but I'm open for every suggestion! :) UPDATE: Never mind, didn't work...

In reply to localizing lexical without messing with tie ? by LanX

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.