Mastering Modern Perl: Writing Efficient and Maintainable Code/

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Types of References II

Types of References II

Learn about some more types of references in Perl.

We'll cover the following...

Function references

Perl supports first-class functions; a function is a data type like an array or hash. In other words, Perl supports function references. This enables many advanced features like closuresA closure is a function that uses lexical variables from an outer scope.. We can create a function reference by using the reference operator and the function sigil & on the name of a function:

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sub bake_cake { say 'Baking a wonderful cake!' };
my $cake_ref = \&bake_cake;
say $cake_ref;

Without the function sigil &, we will take a reference to the function’s return value or values.

Creating anonymous functions

We can create anonymous functions with the bare sub keyword:

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my $pie_ref = sub { say 'Making a delicious pie!' };
$pie_ref->();

The sub built-in used without a name compiles the function but doesn’t register it with the current namespace. The only way to access this function is via the reference returned from sub. Invoke the function reference with the dereferencing arrow:

$cake_ref->();
$pie_ref->();

Note: An alternate invocation syntax for function references uses the function sigil ...