Re: are they all there?

Since, as you say, your 'collections' are strings, you could consider something like the following:

my @required = qw ( apple banana orange pear );

my @collections = (
  'foo pear bar apple',
  'apple foo pear orange banana',
  'pineapple appearance',
);

foreach my $collection ( @collections ) {
  foreach my $item ( @required ) {
    $collection .= " $item" unless $collection =~ /\b$item\b/;
  }
}

print "$_\n" for @collections;
[download]

Update: ikegami++ (see below). I haven't changed the code in this node, but please use the suggested improvement.

Comment on Re: are they all there? Download Code

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Re^2: are they all there? by ikegami (Patriarch) on Aug 22, 2006 at 18:30 UTC
Nice, but instead of compiling {number of collections} * {number of required items} regexps, swap your loops to only compile {number of required items} regexps. `foreach my $item ( @required ) { foreach my $collection ( @collections ) { $collection .= " $item" unless $collection =~ /\b$item\b/; } }` [download]	[reply] [d/l]
Re^3: are they all there? by ikegami (Patriarch) on Aug 23, 2006 at 19:24 UTC
I was asked How do we know that perl is smart enough not to recompile the regexp with every iteration of the inner loop nonetheless? We can use `use re 'debug';` to see the difference. `use re 'debug'; for my $i (1..2) { for my $re (qw( abc def )) { $i =~ /$re/; } }` [download] ouputs Compiling REx `abc' <------------ size 3 first at 1 1: EXACT <abc>(3) 3: END(0) anchored `abc' at 0 (checking anchored isall) minlen 3 Freeing REx: `abc' Compiling REx `def' <------------ size 3 first at 1 1: EXACT <def>(3) 3: END(0) anchored `def' at 0 (checking anchored isall) minlen 3 Freeing REx: `def' Compiling REx `abc' <------------ size 3 first at 1 1: EXACT <abc>(3) 3: END(0) anchored `abc' at 0 (checking anchored isall) minlen 3 Freeing REx: `abc' Compiling REx `def' <------------ size 3 first at 1 1: EXACT <def>(3) 3: END(0) anchored `def' at 0 (checking anchored isall) minlen 3 Freeing REx: `def' [download] while `use re 'debug'; for my $re (qw( abc def )) { for my $i (1..2) { $i =~ /$re/; } }` [download] outputs Compiling REx `abc' <------------ size 3 first at 1 1: EXACT <abc>(3) 3: END(0) anchored `abc' at 0 (checking anchored isall) minlen 3 Freeing REx: `abc' Compiling REx `def' <------------ size 3 first at 1 1: EXACT <def>(3) 3: END(0) anchored `def' at 0 (checking anchored isall) minlen 3 Freeing REx: `def' [download] If the interpolated variables are still the same as they were the last time the regexp was compiled, the regexp is not recompiled. Update: We get the same results with `/\b$re\b/`.	[reply] [d/l] [select]