[tpm] Lightning Talk lineup

Alex Beamish talexb at gmail.com
Fri Oct 3 09:39:08 PDT 2008

On Tue, Sep 30, 2008 at 5:27 PM, Dave Doyle <dave.s.doyle at gmail.com> wrote:
> (with apologies to Ilia for sending it to him first instead of the list...
> damn reply button)
> Side note from my Lightning talk.
> It came up at one point why when I was defining an attribute I did this:
> has 'x' => (
>     is    => 'rw',
>     isa  => 'HashRef',
>     default => sub { +{} },
> );
> In Moose, if you're defining a type with a default that is not a scalar, you
> have to use an anonymous sub.  But in all the Moose examples for hashrefs,
> you see the "sub { +{} }".  The good Abbot Beamish questioned me on this
> peculiar plus sign and I guessed was because the Perl interpreter needed to
> disambiguate the use of the braces ( a BLOCK or a HASHREF ).

Hi Dave!

Amazingly enough, I actually used this new-found piece of knowledge
today, building an array of hashrefs for a call to a library that I
cannot (yet) change:

  my @symbols = map { +{ 'key' => $_ } } @things;

Proof once again that Perl is an unbelievably powerful language. I'm
glad you used it, and I asked you about it. :)

Alex Beamish
Toronto, Ontario
aka talexb

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