in reply to Re: Re: Re: Link a hash and an array
in thread Link a hash and an array

@Stuff{@{$Types{$_[0]}}} = @_;

[download]

This syntax is interesting. I have now copied it without fully understanding it. This part: 

@{$Types{$_[0]}}

[download]

Seems to indicate, "Pull me the contents of this array element, and return it to me as an array". Am I correct?

The outer curly braces intrige me. I am sure that I read somewhere that the syntax should be: 

@$Types{$_[0]}

[download]

Which I tried with little success. The braced version does work, but I hate to do things by magic. What do they mean?

Again, Thank you,

Skip

Replies are listed 'Best First'.
Re: Re: Re: Re: Re: Link a hash and an array
by QM (Parson) on Mar 12, 2004 at 16:35 UTC
    Sorry, I should have broken it down for you. 

    @Stuff{@{$Types{$_[0]}}} = @_;

    [download]
    Working from the inside out. $_[0] is the 0th element of @_. If its value is "addr", then the value of $Types{"addr"} is \@Address (a reference to the global @Address).

    @{\@Address} takes the reference and "returns" the array it points to. @Stuff{@Address}, known as a "hash slice", is assigned the values in the @_ array, and is equivalent to this: 

    @Stuff{@Address} = qw(addr bob smith '1234 main st' anytown 20500);

    [download]
    A hash slice is just shorthand for this: 
    $Stuff{type} = 'addr';
$Stuff{firstname} = 'bob';
...
$Stuff{zip} = '20500';

    [download]

    [I hope that was clear]

    -QM
    --
    Quantum Mechanics: The dreams stuff is made of

[reply]
[d/l]
[select]

      Thank you for breaking that down. That is what I thought you meant.

      I sometimes give the impression that I have more of a clue than I do. Often I have beaten on some narrow area that I can talk intellegently about it, but look like an absolute fool when talking about something closely related. I am learning perl. I will get there.

      Skip
[reply]
[d/l]

In Section Seekers of Perl Wisdom