RE: RE: Re: Perlmonks Code Proxy

The /e causes the right hand side of s/// to be handled as code to eval. Well, since we are deliberately matching Perl code with this regex, this solution tends to choke quite spectacularly.

Hmmm... Thats strange. I decided to fool around with it and tried this out:

my $i = 1;
my $string = 'print "hello";';
my $content = 'print "hello";$x + 2; print "hello";print "hello";print
+ "hello";';

$content =~ s/($string)/$1.$i++."\n"/ge;

print "$content\n";

eval $string;
[download]

and it printed out

print "hello";1
$x + 2; print "hello";2
print "hello";3
print "hello";4

hello
[download]

It doesn't seem that it executed the print statement that was matched, even though if we hand the string directly to exec, it does print out hello.

Comment on RE: RE: Re: Perlmonks Code Proxy Select or Download Code

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RE (tilly) 4: Perlmonks Code Proxy by tilly (Archbishop) on Aug 19, 2000 at 01:28 UTC
Right hand side, not left: `$str = "Hello world\n"; $str =~ s/o/print "Got an o!\n"/eg; print $str;` [download]	[reply] [d/l]
RE: RE (tilly) 4: Perlmonks Code Proxy by Boogman (Scribe) on Aug 19, 2000 at 01:49 UTC
yeah - I was saying that if you matched code on the right side, and then used that code in the eval expression with $1, it wouldnot get executed. AKA, saying `s/(stuff)/$1/eg` would not do anything even if the stuff captured in $1 was perl code. `$string = "print 'got an o\n'"; $string =~ s/(.*)/$1/eg;` [download] Doesn't print anything.	[reply] [d/l] [select]
RE (tilly) 6: Perlmonks Code Proxy by tilly (Archbishop) on Aug 19, 2000 at 02:42 UTC
OK, I misunderstood what you were trying to figure out. Even so ehis should not be a surprise. Execute the statement $var and nothing happens except that the contents of $var are returned. Same thing with $1. Execute it and it returns the contents of $1 as a string, presumably to be placed back in the original string. But try using the modifier /eeg and see what that does. :-)	[reply]