Re: Re^7: Grep Pattern Match

A rather simpler test method, but in this, (only) "line 1" is printed out 10 times.

#! perl -sw
use strict;

my $count=1;
my $regex = qr/$count/;
my $told = tell DATA;
my $line;
for $count (1 .. 10) {
    $line =~ $regex and print $line while $line = <DATA>;
    seek DATA, $told, 0;
}

__DATA__
line 1
line 2
line 3
line 4
line 5
line 6
line 7
line 8
line 9
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Comment on Re: Re^7: Grep Pattern Match Download Code

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Re^9: Grep Pattern Match by diotalevi (Canon) on Dec 27, 2002 at 19:48 UTC
Oh but that's not at all the same. It's quite obvious (to me anyway) that $count is being compiled each time. The only reason I brought this up was I didn't know whether the invariant regex in a block attacked to a grep was going to be recompiled each time or not. There's an opportunity for perl to notice that the regex only needs to compiled once - the question here is on whether it takes it or not. Update: Oops! I thought you said `$line =~ $count` where you actually said `$line =~ $regex`. Anyhow I still think you've misunderstood which question I was asking. Fun Fun Fun in the Fluffy Chair	[reply] [d/l] [select]

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Re^9: Grep Pattern Match
by diotalevi (Canon) on Dec 27, 2002 at 19:48 UTC

Oh but that's not at all the same. It's quite obvious (to me anyway) that $count is being compiled each time. The only reason I brought this up was I didn't know whether the invariant regex in a block attacked to a grep was going to be recompiled each time or not. There's an opportunity for perl to notice that the regex only needs to compiled once - the question here is on whether it takes it or not.

Update: Oops! I thought you said $line =~ $count where you actually said $line =~ $regex. Anyhow I still think you've misunderstood which question I was asking.

Fun Fun Fun in the Fluffy Chair

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