The Switch.pm module implements a generalized case mechanism that covers
most (but not all) of the numerous possible combinations of switch and
case values described above.The module augments the standard Perl syntax
with two new control statements: 'switch' and 'case'. The 'switch'
statement takes a single scalar argument of any type, specified in
parentheses. 'switch' stores this value as the current switch value in a
(localized) control variable. The value is followed by a block which may
contain one or more Perl statements (including the 'case' statement
described below). The block is unconditionally executed once the switch
value has been cached. A 'case' statement takes a single scalar argument
(in mandatory parentheses if it's a variable; otherwise the parens are
optional) and selects the appropriate type of matching between that
argument and the current switch value. The type of matching used is
determined by the respective types of the switch value and the 'case'
argument, as specified in Table 1. If the match is successful, the
mandatory block associated with the 'case' statement is executed.

Author:
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Damian Conway