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Set::String - Strings as objects with lots of handy methods (including set comparisons) and support for method chaining.


my $s1 = Set::String->new("Hello");

my $s2 = Set::String->new("World!\n");

$s1->length->print; # prints 5

$s1->ord->join->print; # prints 72,101,108,108,111

$s2->chop(3)->print; # prints 'Worl'


Perl 5.6 or later

Set::Array (also by me). Available on CPAN.

The 'Want' module by Robin Houston. Available on CPAN.


Set::String allows you to create strings as objects and use OO-style methods on them. Many convenient methods are provided here that appear in the FAQ's, the Perl Cookbook or posts from comp.lang.perl.misc. In addition, there are Set methods with corresponding (overloaded) operators for the purpose of Set comparison, i.e. +, ==, etc.

The purpose is to provide built-in methods for operations that people are always asking how to do, and which already exist in languages like Ruby. This should (hopefully) improve code readability and/or maintainability. The other advantage to this module is method-chaining by which any number of methods may be called on a single object in a single statement.

Note that Set::String is a subclass of Set::Array, and your string objects are really just treated as an array of characters, ala C. All methods available in Set::Array are available to you.


The exact behavior of the methods depends largely on the calling context.

Here are the rules:

* If a method is called in void context, the object itself is modified.

* If the method called is not the last method in a chain (i.e. it's called in object context), the object itself is modified by that method regardless of the 'final' context or method call.

* If a method is called in list or scalar context, a list or list refererence is returned, respectively. The object itself is NOT modified.

Here is a quick example:

my $so = Set::String->new("Hello");

my @uniq = $so->unique(); # Object unmodified.

$so->unique(); # Object modified, now contains 'Helo'

Here are the exceptions:

* Methods that report a value, such as boolean methods like defined(), never modify the object.


defined() - Returns 1 if the string is defined. Otherwise a 0 is returned.


chomp(?int?) - Deletes the last character of the string that corresponds to $/, or the newline by default. Optionally you may pass an integer to this method to indicate the number of times you want the string chomped. In list context, a list of chomped values is returned. In scalar context, the number of chomped values is returned.

chop(?int?) - Deletes the last character of the string. Optionally you may pass an integer to this method to indicate the number of times you want the string chopped. In list context, a list of chopped values is returned. In scalar context, the number of chopped values is returned.

crypt(salt) - Encrypts the string, converting it into a 13-character string, with the first two characters as the salt. Unlike Perl's builtin crypt function, you CAN decrypt the object to get the original string using the decrypt() method.

decrypt - Decrypts an encrypted string. Attempting to decrypt an unencrypted string will generate a warning. Returns the decrypted string in either list or scalar context.

eval - Evaluates the string and returns the result.

index(substring) - Returns the position of the first occurrence of substring within the string. If the index is not found, a -1 is returned instead.

lc(?int?) - Lower case the string. Optionally, you may pass an integer value to this method, in which case only that number of characters will be lower cased (left to right), instead of the entire string.

lcfirst - Lower case the first character of the string.

ord(?int?) - Converts the string to a list of ord values, one per character. Alternatively, you may provide an optional integer argument, in which case only that number of characters will be converted to ord values. An array or array ref of ord values is returned in list or scalar context, respectively.

pack(template) - Packs the string according to the template provided

pos(pattern) - Returns the location in your string where the last global search left off. If more than one location is found, it will return an array of integers (or an array ref in scalar context).

substr(offset,?length?) - Returns a substring of the object string, starting at offset (with 0 as the first char) and continuing until length, or the end of the string if the length is not specified. If the offset is negative, then it will start at the end of the string.

Returns the substring in either list or scalar context.

uc(?int?) - Upper case the string. Otherwise identical to the 'lc()' method, above.

unpack(template) - Unpacks the string according to the template. Probably best used when *not* part of a chain, as your result will always be concatenated into one big string otherwise.


How can you decrypt an encrypted string? How are you doing this?

When the crypt() method is called, a copy of the original string is placed in a lexical variable within the package. Since there's no way to access that variable *except* through the object (as far as I know), your string is secure.

Note that I wouldn't rely on crypt() to provide true encryption. For that, you ought to be using one of the more modern cryptographic modules.


None. Please let me know if you find any.


Add the 'vec' method

Allow arguments to be passed to the 'eval()' method. I am not sure what the behavior should be at that point, however. Should it replace the string object? Should the results of that evaluation be appended to the original string? Ideas welcome.

Add character ranges to some of the methods

How about a boolean method 'palindrome'? Perhaps a subclass of Set::String, called Set::String::Grammar. It could have a series of boolean methods like 'verb()', 'adjective()', etc.


Daniel Berger