You said:
Finally, this is really the task of the "e" modifier.
$string =~ s/(abc)/ sprintf("%s def(%s)", $1, $x++) /eig;
Now you're getting directly to my point. Let's now rewrite this to using a while loop, as in:

while ($string =~ s/(abc)/  sprintf("%s def(%s)", $1, $x)  /eig) {
    die "oops" if $x++ > 10;
}

[download]

Why doesn't this work? If you remove the 'g' modifier, it still doesn't work -- it just runs in an infinite loop.

I think what I'm getting to is that I assumed that the "progressive" aspect of regex applied to both matching and substitution, since each of those has the common root of matching. (ie., substitution requires at least a match in order to do the substitution) If that were the case, then the above should work. Because it doesn't, the code has to be downgraded to using multiple lines that include the use of pos and such. In the live code where this applies, calls to other functions have to be made, which is why there has to be a loop, not just a simple s/// expression as your example illustrates. Granted, the "substitution" aspect can be as simple as you have, but the value of $x is derived from other code and various tests and manipulations. That's why my "simple" example uses $x++ inside the while loop, to illustrate that it has to be separate from the s/// part.

Dan Heller
http://www.danheller.com

In reply to Re^2: Progressive matching w/substitutions by argv
in thread Progressive matching w/substitutions by argv

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