I agree, testing your code you need to either do as rollyguy has suggested, or it does work doing:
open (PROG, "+>>$0");

[download]
In running your code withthe + in it, I have found your regexp does not work as well.
Here is my version, and followed by the output: 

#!/usr/bin/perl

use strict;
use warnings;

my $new_value = 10;
my $data=45;

open (PROG, "+>>$0");
seek (PROG, 0, 0);     #not working 
while (<PROG>)
{
  s/^(my .data\s*=\s*)\d+(\s*;)/$1.$new_value.$2/e;
  print;
}
close (PROG);

[download]
Output:
#!/usr/bin/perl

use strict;
use warnings;

my $new_value = 10;
my $data=10;

open (PROG, "+>>$0");
seek (PROG, 0, 0);     #not working 
while (<PROG>)
{
  s/^(my .data\s*=\s*)\d+(\s*;)/$1.$new_value.$2/e;
  print;
}
close (PROG);

[download]

Note: I'm not writing to the file itself, now that I'm thinking about it you probably want to write a temp file, then copy it over....

Hope this helps!

In reply to Re: Re: substitution in $0 by Helter
in thread substitution in $0 by Discipulus

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