Perl Pocket Reference, 4th Edition

Chapter 34. Miscellaneous

defined expr†

Tests whether the scalar expression has an actual value.

do { expr ; . .. }

Executes the block and returns the value of the last expression. See also the section Chapter 11.

do filename

Executes filename as a Perl script. See also require.

eval { expr ; ... }

Executes the code between { and }. Traps runtime errors and returns as described with eval(expr).

local [ our ] variable

Gives a temporary value to the named package variable, which lasts until the enclosing block, file, or eval exits. variable may be a scalar, an array, a hash, or an element (or slice) of an array or hash.

my variable

Creates a scope for the variable lexically local to the enclosing block, file, or eval.

my [ class ] variable [ attributes ]

Experimental. Built-in attribute is :shared. Module Attribute::Handlers can be used to define additional attributes.

our variable

Declares the variable to be a valid global within the enclosing block, file, or eval.

our [ class ] variable [ attributes ]

Experimental. Built-in attributes are :shared and :unique. Module Attribute::Handlers can be used to define additional attributes.

ref expr†

Returns true if expr is a reference. Returns the package name if expr has been blessed into a package.

reset [ expr ]

expr is a string of single letters. All variables in the current package beginning with one of those letters are reset to their pristine state. If expr is omitted, resets ?? searches so that they work again.

undef [ lvalue ]

Undefines the lvalue. Always ...