There were several suggested methods in answer to this thread. My solution repeatedly substituted in a while loop. I got to wondering if you could do a global substitution in one fell swoop instead by assigning to pos in a regex code block to set the match back to the start of the string. This doesn't seem to work although the assignment to pos() does seem to register. Here's a short script to show what I'm trying, firstly the loop variant then the global substitution.

#!/usr/local/bin/perl -l
#
use strict;
use warnings;

$_ = q{DFR7234C__A_B_C_Bonzo_Dog_D_B};
print;

1 while s
   {
      (?<=__)
      [A-Z]_
   }
   {}x;

print;
print q{-} x 25;

$_ = q{DFR7234C__A_B_C_Bonzo_Dog_D_B};
print;

s
   {
      (?<=__)
      [A-Z]_
      (?{
            print pos();
            pos() = 0;
            print pos()
        })
   }
   {}gx;

print;
print q{-} x 25;

[download]

Here's the output

DFR7234C__A_B_C_Bonzo_Dog_D_B
DFR7234C__Bonzo_Dog_D_B
-------------------------
DFR7234C__A_B_C_Bonzo_Dog_D_B
12
0
DFR7234C__B_C_Bonzo_Dog_D_B
-------------------------

[download]

As you can see, it doesn't look as if matching is reset so only one substitution is done. Am I trying to do something impossible here?

Cheers,

JohnGG

In reply to Can you assign to pos() in a s/foo/bar/g by johngg

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