Re: hash deref confusion: Intermediate Perl

But, in the next line, "@$self" is syntax for dereferencing an array reference, not a hash reference!

This is called a hash slice , and in a quirk of perl syntax uses the @ sigil instead of %

my %foo; @foo{ 'hash', 'slices' } = ( 'use', 'curly braces' );

my @bar; @bar[ 1,2,3,4 ] = ( 'array', 'slices', 'use', 'square brackets' );

Comment on Re: hash deref confusion: Intermediate Perl

Replies are listed 'Best First'.
Re^2: hash deref confusion: Intermediate Perl by tobyink (Canon) on Jul 30, 2012 at 07:03 UTC
I wouldn't really say it's a quirk. You're assigning a list of values to a list of hash slots, so the `@` sigil is quite appropriate. `perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'`	[reply] [d/l]
Re^3: hash deref confusion: Intermediate Perl by Anonymous Monk on Jul 30, 2012 at 08:13 UTC
I wouldn't really say it's a quirk. You're assigning a list of values to a list of hash slots, so the @ sigil is quite appropriate. Sure, from that perspective it makes sense, but IIRC TheLarry himself called this a mistake, its why perl6 always calls a %hash a `%hash{$key}` not `$hash{$key}`	[reply] [d/l] [select]
Re^4: hash deref confusion: Intermediate Perl by tobyink (Canon) on Jul 30, 2012 at 08:30 UTC
That's not specific to slices though. In Perl 6 sigils are not context-dependent; they are variable-dependent and context-invariant. In Perl 5, where sigils are used to indicate context, using `@` for hash slices is pretty consistent with the rest of the language. `perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'`	[reply] [d/l]
Re^5: hash deref confusion: Intermediate Perl by Anonymous Monk on Jul 30, 2012 at 08:37 UTC
Re^2: hash deref confusion: Intermediate Perl by live4tech (Sexton) on Jul 30, 2012 at 14:09 UTC
Thank you! This is a very clear and concise answer. I find it difficult to remember all the syntax in perl (also true especially of all the special symbols $....	[reply]


good chemistry is complicated, and a little bit messy -LW
	PerlMonks