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String::Random.3pm

NAME

String::Random - Perl module to generate random strings based on a pattern

SYNOPSIS

   use String::Random;
   $foo = new String::Random;
   print $foo->randregex('\d\d\d'); # Prints 3 random digits
   print $foo->randpattern("...");  # Prints 3 random printable characters
 
 

or

   use String::Random qw(random_regex random_string);
   print random_regex('\d\d\d'); # Also prints 3 random digits
   print random_string("...");   # Also prints 3 random printable characters
 
 

DESCRIPTION

This module makes it trivial to generate random strings.

As an example, let's say you are writing a script that needs to generate a random password for a user. The relevant code might look something like this:

   use String::Random;
   $pass = new String::Random;
   print "Your password is ", $pass->randpattern("CCcc!ccn"), "\n";
 
 

This would output something like this:

   Your password is UDwp$tj5
 
 

If you are more comfortable dealing with regular expressions, the following code would have a similar result:

   use String::Random;
   $pass = new String::Random;
   print "Your password is ",
       $pass->randregex('[A-Z]{2}[a-z]{2}.[a-z]{2}\d'), "\n";
 
 

Patterns

The pre-defined patterns (for use with "randpattern()" and "random_pattern()") are as follows:

   c        Any lowercase character [a-z]
   C        Any uppercase character [A-Z]
   n        Any digit [0-9]
   !        A punctuation character [~`!@$%^&*()-_+={}[]|\:;"'.<>?/#,]
   .        Any of the above
   s        A "salt" character [A-Za-z0-9./]
   b        Any binary data
 
 

These can be modified, but if you need a different pattern it is better to create another pattern, possibly using one of the pre-defined as a base. For example, if you wanted a pattern "A" that contained all upper and lower case letters ("[A-Za-z]"), the following would work:

   $foo = new String::Random;
   $foo->{'A'} = [ 'A'..'Z', 'a'..'z' ];
 
 

or

   $foo = new String::Random;
   $foo->{'A'} = [ @{$foo->{'C'}}, @{$foo->{'c'}} ];
 
 

The random_string function, described below, has an alternative interface for adding patterns.

Methods

new

new max => number

Create a new String::Random object.

Optionally a parameter "max" can be included to specify the maximum number of characters to return for "*" and other regular expression patters that don't return a fixed number of characters.

randpattern LIST

The randpattern method returns a random string based on the concatenation of all the pattern strings in the list.

It will return a list of random strings corresponding to the pattern strings when used in list context.

randregex LIST

The randregex method returns a random string that will match the regular expression passed in the list argument.

Please note that the arguments to randregex are not real regular expressions. Only a small subset of regular expression syntax is actually supported. So far, the following regular expression elements are supported:

   \w    Alphanumeric + "_".
   \d    Digits.
   \W    Printable characters other than those in \w.
   \D    Printable characters other than those in \d.
   .     Printable characters.
   []    Character classes.
   {}    Repetition.
   *     Same as {0,}.
   ?     Same as {0,1}.
   +     Same as {1,}.
 
 

Regular expression support is still somewhat incomplete. Currently special characters inside [] are not supported (with the exception of ``-'' to denote ranges of characters). The parser doesn't care for spaces in the ``regular expression'' either.

Functions

random_string PATTERN,LIST

random_string PATTERN

When called with a single scalar argument, random_string returns a random string using that scalar as a pattern. Optionally, references to lists containing other patterns can be passed to the function. Those lists will be used for 0 through 9 in the pattern (meaning the maximum number of lists that can be passed is 10). For example, the following code:

   print random_string("0101",
                       ["a", "b", "c"],
                       ["d", "e", "f"]), "\n";
 
 

would print something like this:

   cebd
 
 

BUGS

This is Bug Free(TM) code. (At least until somebody finds one...)

AUTHOR

Steven Pritchard <steve@silug.org>

SEE ALSO

perl(1).