Programming Perl, 4th Edition

reset

reset EXPR
reset

This function is generally used (or abused) at the top of a loop or in a continue block at the end of a loop to clear global variables or reset m?? searches so that they work again. The expression is interpreted as a list of single characters (hyphens are allowed for ranges). All scalar variables, arrays, and hashes beginning with one of those letters are reset to their pristine state. If the expression is omitted, one-match searches (m?PATTERN?) are reset to match again. The function resets variables or searches for only the current package. It always returns true.

To reset all “X” variables, say this:

reset "X";

To reset all lowercase variables, say this:

reset "a–z";

Lastly, to just reset ?? searches, say:

reset;

Resetting “A–Z” in package main is not recommended since you’ll wipe out your global ARGV, INC, ENV, and SIG arrays and hashes.

Lexical variables (created by my) are not affected. Use of reset is vaguely deprecated because it easily clears out entire namespaces, and because the ?? operator is itself vaguely deprecated; please use m?? instead.

See also the delete_package function from the standard Symbol module, and the whole issue of Safe compartments documented in the section Safe Compartments in Chapter 20.