Mathieu,
Thank you, you gave me just the clue I needed! BTW, the parameter
thing is required or else it returns a blank string. Here's what
works:
############################################################
# Position and character would normally be determined
# by user input, but are hard-coded here for brevity
my $position = 2; # Is always a number, 1-4
my $character = "~"; # Can be any "special" char
# Build substitution for later use
my $substitute;
if ( $position == 1 ) { # s/^(.*)$/~$1/
$substitute = sub { $_[0] =~ s/^(.*)$/$character$1/; return $_[0] };
}
elsif ( $position == 2 ) { # s/^(.*)(\.[^.]+)$/$1~$2/
$substitute = sub { $_[0] =~ s/^(.*)(\.[^.]+)$/$1$character$2/; return
$_[0] };
}
elsif ( $position == 3 ) { # s/^(.*\.)([^.]+)$/$1~$2/
$substitute = sub { $_[0] =~ s/^(.*\.)([^.]+)$/$1$character$2/; return
$_[0] };
}
elsif ( $position == 4 ) { # s/^(.*)$/$1~/
$substitute = sub { $_[0] =~ s/^(.*)$/$1$character/; return $_[0] };
}
else {
die "Invalid position: $position\n";
}
# Loop thousands of times
for ( 0..99_000 ) {
# Filename would be different every time
my $filename = "filename.plus.ext";
#$filename = $substitute->( $filename );
$substitute->( $filename );
print "$filename\n";
}
############################################################
I really appreciate the suggestions I received from you and Brian
Raven.
-Brian
-----Original Message-----
Mathieu Longtin wrote:
As somebody else pointed out: s/$regexp/whatever/
If you need the whatever to be evaluated early as well, you could
build a sub
my $regexp = qr/.../;
my $replace = ...;
my $replacer = sub { s/$regexp/$replace/; };
Then in your loop:
$_ = whateverstringneedsreplacing;
$replacer->();
The result of the substitution is in $_.
You could also do something cleaner with parameters:
my $replacer = sub { $_[0] =~ s/$regexp/$replace/; return $_[0] };
Then in the loop:
my $subresult = $replacer->($whateverstringneedsreplacing);
Note that you could use
$replacer = eval "sub {...}" ;
instead of
$replacer = sub { ... } ;
so that perl compiles the regex only once. Not entirely if it would
speed it up.
-Mathieu
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