How does glob return 'filenames' that don't exist?

Question

This answer indicates that glob can sometimes return 'filenames' that don't exist.

@deck = glob "{A,K,Q,J,10,9,8,7,6,5,4,3,2}{\x{2660},\x{2665},\x{2666},\x{2663}}";

However, that code returns an empty list when I run it.

What am I missing?

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This run was from the command prompt using -e, on Windows XP, with ActiveState Perl version 5.005_02. Running from a saved script on the same machine yields the same results.

Running with -e on Windows XP, with ActiveState Perl v5.8.7, does return an array.

Answer 1

Perl version 5.005_02 is ancient (in Perl terms). That version probably has a different implementation of glob that doesn't return names of files that don't exist. As you've noticed, later versions of Perl work differently.

Answer 2

That works correctly on my machine, v5.10.0.

#!/usr/bin/perl

@deck = glob "{A,K,Q,J,10,9,8,7,6,5,4,3,2}{\x{2660},\x{2665},\x{2666},\x{2663}}";

print @deck

gives as output:

A♠A♥A♦A♣K♠K♥K♦K♣Q♠Q♥Q♦Q♣J♠J♥J♦J♣10♠10♥10♦10♣9♠9♥9♦9♣8♠8♥8♦8♣7♠7♥7♦7♣6♠6♥6♦6♣5♠5♥5♦5♣4♠4♥4♦4♣3♠3♥3♦3♣2♠2♥2♦2♣

Answer 3

It works well for me - i.e. it generates deck of cards, I'm using perl 5.8.8.

But. Using glob for this seems to be strange - I mean - sure, it's possible, but glob is a tool to match files which is not guaranteed to actually check for the files, but nobody says that it will not match the files in the future!

I would definitely go with another approach. For example like this:

my @cards = qw( A K Q J 10 9 8 7 6 5 4 3 2 );
my @colors = ( "\x{2660}", "\x{2665}", "\x{2666}", "\x{2663}" );

my @deck = map {
    my $card = $_;
    map { "$card$_" } @colors
} @cards;

Or, if you find the map{map} too cryptic:

my @deck;
for my $card ( @cards ) {
    for my $color ( @colors ) {
        push @deck, "$card$color";
    }
}