On Thu, Feb 07, 2002 at 03:15:49PM +0000, Richard Clamp wrote:
> On my current project, we've noticed, at quite an annoying time, that
> the fat comma (=>) is treated differently than we initially expected
> for calling methods.
It's a feature.
The idea being that you can have positional arguments and named arguments
and TT recognises the difference and bundles all the named params into
a hash for you.
> foo.bar(foo => 'bar') gets magically mutated into { foo => 'bar' }
> foo.bar('foo', 'bar') passes two elements, ( 'foo', 'bar' )
foo.bar('foo', x => 'y', 'bar', wiz => 'waz')
=> ('foo', 'bar', { x => 'y', wiz => 'waz' })
In TTsville, it's important to have a distinction between positional and
named arguments (although I must admit I'm hard pressed to think of the
Very Good Reason right now). There was no precedent for named params
in Perl so I had to set one. I chose to bundle all named params
together and pass them by hash ref as the last argument.
> Which surprised me, as I was expecting the more perlish (foo => 'bar')
> becomes ('foo', 'bar'), and so were the methods we'd written.
TT treats both '=' and '=>' equally and I tend to use the former so as
not to confuse myself into a Perl way of thinking.
e.g.
foo.bar(foo='bar')
I admit it can be confusing if you're expecting '=>' to behave like it
does in Perl, but I suppose my justification is that TT isn't Perl (except
when it wants to be) :-)
> Is this intended, or just an implementation feature of the => operator
> in TT? Also, is there an easy way to switch the behaviour to what I
> was expecting.
It happens in the parser. You could subclass/hack the parser to behave
more Perl-like but then you might find it made other things blow up that
expect that behaviour.
For more info, it's documented here:
http://tt2.org/docs/leon/Manual/Variables.html#Parameters_and_Return_Values
HTH
A
