It's a fine technique to use but you need to be a little careful about how you use it. Using double quotes to quote the pattern is a sure way to shoot yourself in the foot. It is better to use qr() for this.

Take your example, for example... 

%character_tests{ "var1" , "^0-9",
                  "var2" , "^A-Za-z0-9\." );

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The first problem is that your hash initialization is all messed up and you have a typo too. We'll ignore that for the time being. The second problem with that is that you almost surely want character classes. I.e. "^0-9" will match a string that starts with the literal string "0-9". You mean probably mean either "[^0-9]" (anything that isn't a digit, better represented as \D) or "^[0-9]" (anything that starts with a digit, better represented by '^\d'. I'm going to assume its the latter you really wanted. See how I used single quotes around it? That's because if I used double quotes the \d would have looked like an escaped "d" which is simply a literal "d". So, the resulting regex would have matched anything that started with a "d" instead of a digit. That's why you shouldn't use double quotes.

As I said, the qr() quoting operator is provided for just this sort of thing. You could write the snippet above as... 

%character_tests = ( 
    var1 => qr/^0-9/,
    var2 => qr/^A-Za-z0-9\./ 
);

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First, notice the assignment? That's required to initialize the hash. Notice also that I use parens. Braces are for hash refs. Don't worry about them right now. You really should pick more descriptive keys but those will suffice for now.

You would use such a regex like this: 

$somestring =~ $character_tests{var1};

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You can also use them inside another regex. 
 
$somestring =~ /$character_tests{var1}Foo/;

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Read perldoc perlop for more information on qr() and perldoc perlre for more information on regular expressions in general. 

-sauoq
"My two cents aren't worth a dime.";

In reply to Re: regex variables by sauoq
in thread regex variables by Angel

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