Curly braces for a hash

Question

Which structure is created as following in Perl?

my $self = { Name => $name, Color => $class->default_color };

If it is a hash, then is the official notation not the following ( parentheses, % instead of $):

my %self = ( Name => $name, Color => $class->default_color );

http://stackoverflow.com/questions/1817394/whats-the-difference-between-a-hash-and-hash-reference-in-perl — martin clayton, Sep 09 '12 at 20:49
I take it you're reading [Intermediate Perl](http://www.intermediateperl.com). :) — brian d foy, Sep 09 '12 at 22:29
Just for reference, the `{}` are usually referred to `"curly"` braces. "angle" ones are "<>" — DVK, Sep 10 '12 at 15:05

score 5 · Accepted Answer · answered Sep 09 '12 at 20:49

5

The data in { ... } is a hash ref.

The data in ( ... ) is a list, but the context makes it into a hash.

answered Sep 09 '12 at 20:49

Jonathan Leffler

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raina77ow · Answer 2 · 2012-09-09T20:55:38.187

3

Well, it's still a hash - but an anonymous one. And its reference is assigned to $self. The doc says:

A reference to an anonymous hash can be created using curly brackets:

$hashref = {    
  'Adam'  => 'Eve',     
  'Clyde' => 'Bonnie',
};

edited Sep 09 '12 at 20:55

answered Sep 09 '12 at 20:49

raina77ow

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score 3 · Answer 3 · answered Sep 09 '12 at 22:27

Perl doesn't have a literal representation of a hash, so we create a hash as a list of key-value pairs. The anonymous hash constructor or assignment to named hash converts the list of key-value pairs to a hash.

The top line creates a hash reference which you assign to a scalar variable:

my $self = { Name => $name, Color => $class->default_color };

The bottom line assigns a list to a named hash:

my %self = ( Name => $name, Color => $class->default_color );

Curly braces for a hash

3 Answers3