How can POE use a hash reference like a hash?

sunshine_august has asked for the wisdom of the Perl Monks concerning the following question:

hi, all monks:

I am learning POE, and I am confused about POE::Session's parameter HEAP.

I notice that POE::Session use its parameter HEAP like a hash, but I think HEAP should be a reference, and it is documented: " Heaps are by default anonymous hash references":

The example from its document:

 sub _start_handler {
    $_[HEAP]{ts_start} = time();
  }
[download]

why does it use

$_[HEAP]{ts_start} = time();
[download]

rather than

$_[HEAP]->{ts_start} = time();
[download]

I think the $_[HEAP] should be a reference, it can't not be use like $_[HEAP]{ts_start}, but in POE::Session, it did use like this way and it did work well.

Can anyone give a tip?

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Re: How can POE use a hash reference like a hash? by rcaputo (Chaplain) on Dec 11, 2008 at 06:05 UTC
In Perl, the arrow is optional between two subscripts. You can add one if you wish it to be there. `-- Rocco Caputo - http://poe.perl.org/`	[reply]
Re^2: How can POE use a hash reference like a hash? by Bloodnok (Vicar) on Dec 11, 2008 at 17:13 UTC
... not in all cases - Re^2: Multidimensional array. A user level that continues to overstate my experience :-))	[reply]
Re^3: How can POE use a hash reference like a hash? by rcaputo (Chaplain) on Dec 27, 2008 at 15:48 UTC
That node seems to agree with me: Arrows are optional between two subscripts. In `$x->[0]->[1]`, `$x` is not a subscript but both `[0]` and `[1]` are. We may remove the second arrow without changing the expression, giving `$x->[0][1]`. The arrow between `$x` and `[0]` isn't between two subscripts, however, so it is required to maintain equivalence with the original expression. `-- Rocco Caputo - http://poe.perl.org/`	[reply] [d/l] [select]