Re: (Ovid) Re: What's like $+ but not gives the ordinal?

I don't understand why you need to localize the backref variables. Also, you're finding the first capture, not the last.

Here is a way that finds the max by itself, as implied by another message on this thread:

sub last_paren_match_ordinal()
 {
 my $n= scalar @+;  # gives number of captures present.
 while ($n) {
    no strict 'refs';
    last if defined $$n;
    --$n;
    }
 return $n;    
 }
[download]

In your new code, you are localizing the same name as you are my-ing. What's that for? It's not even used inside the block where it's localized.

—John

Comment on Re: (Ovid) Re: What's like $+ but not gives the ordinal? Download Code

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(Ovid) Re(3): What's like $+ but not gives the ordinal? by Ovid (Cardinal) on Jun 28, 2001 at 02:01 UTC
John, this stuff gets a bit tricky because what I've done is write a code generator. I don't understand why you need to localize the backref variables. Because if the match fails on the current attempt, but it succeeded on a previous attempt, the backref variables ($1, $2, etc) will contain the values from the previous match. The following code demonstrates this: `my $string = '1234'; $string =~ /(2)/; $string =~ /(a)/; print $1;` [download] Also, you're finding the first capture, not the last. I misread your post then. Make the following change: `- for ( 1 .. $num_refs ) { + for ( $num_refs .. 1 ) {` [download] Here is a way that finds the max by itself... I didn't know about the `@+` variable :) In your new code, you are localizing the same name as you are my-ing. Actually, I'm not. Before the eval statement, add the statement `print $code;`. That will show you what's going on. The HERE document is a scalar containing generated code to be evaled. That's all. As I mentioned, my code is probably not worth the effort as I did not know about `@+`. :) Update 2: Duh! Of course `$num_refs .. 1` isn't going to work. Sigh. Cheers, Ovid Vote for paco! Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.	[reply] [d/l] [select]
Re: (Ovid) Re(3): What's like $+ but not gives the ordinal? by John M. Dlugosz (Monsignor) on Jun 28, 2001 at 02:25 UTC
I guess there is a lot of powerful stuff going on there that I don't follow. `- for ( 1 .. $num_refs ) { + for ( $num_refs .. 1 ) {` [download] That's not what happens when I try it. For example, `perl -e "$n=5; for($n..1) { print }"` [download] does not print the reverse of `perl -e "$n=5; for(1..$n) { print }"` [download]	[reply] [d/l] [select]