From: "David Nicol" <[EMAIL PROTECTED]>
> On Dec 1, 2007 2:22 PM, Joshua ben Jore <[EMAIL PROTECTED]> wrote:
> > On Dec 1, 2007 8:51 AM, Jenda Krynicky <[EMAIL PROTECTED]> wrote:
> > > From: "David Nicol" <[EMAIL PROTECTED]>
> > > > On Nov 30, 2007 7:24 PM, Jenda Krynicky <[EMAIL PROTECTED]> wrote:
> > > > > I'm missing the reason-for-being of the module it its docs. I read
> > > > > the whole documentation and the test script and I still don't get it.
> > > > >
> > > > > What is it supposed to be used for?
> > > > >
> > > > > Sorry, Jenda
> > > >
> > > > polymorphic functions / more complex prototypes
> > >
> > > Any examples?
>
> Currently when you want to have a sub act differently depending on
> how many arguments are supplied to it, rather than the naive
>
> sub poly($) { print "got one arg, @_\n" }
> sub poly($$) { print "got two args, @_\n" }
>
> working as intended, you have to do something like
>
> sub poly($;$) {
> @_ == 1 and return print "got one arg, @_\n";
> print "got two args, @_\n"
> }
If you do that I assure you you'll hear very soon that you should not
use prototypes. They are great if you need to make sure some
userdefined function has the same interface as a builtin or if you
are trying to add a new syntax (try{} catch {} or something), but
should not be used if all you want is to have a function that takes
one or two parameters.
What does
sub poly($;$) {
@_ == 1 and return print "got one arg, @_\n";
print "got two args, @_\n"
}
@a = (10, 20);
poly(@a);
do? I hope you do know and do expect the result.
> Using Macrame, you can do
>
> sub _poly1arg($) { print "got one arg, @_\n" }
> sub _poly2arg($$) { print "got two args, @_\n" }
> macro poly(one,two) { _poly2arg(one,two) }
> macro poly(one) { _poly1arg(one) }
> macro poly one,two { _poly2arg(one,two) }
> macro poly one { _poly1arg(one) }
Which seems to me much more wordy and harder to understand.
> A feature I believe can be added using 0.08 syntax is the idea of having
> "my" create a reference
>
> macro my \$alias = \$Item; {
> my $alias;
> $alias = \$item;
> macro alias { {NOMACROS $alias} } # from here on, $alias is
> "really" ${$alias}
> }
>
> which may sort of work at this point.
erm ... I wanted to see the use, not the implementation of something
made possible with Macrame. Or is that it?
If you want to create an alias to something you have a reference to
you can do it using for(){} or Data::Alias, Lexical::Alias or
Devel::LexAlias.
> > > Looking at the KNOWN BUGS it doesn't look like this works too well.
> > > Any examples of a "new syntax" that you would like to be able to
> > > create? So that we can see how close would we be able to get without
> > > using source filters.
>
> Macrame _is_ a source filter; it provides a filtering syntax that abstracts
> away
> some parsing steps.
Yes, I know it is a source filter. And has all the problems of source
filters ... that is it can misunderstand something, transform your
source code in completely unexpected way and cause next to impossible
to find bugs. As such it needs to do something really really
important to warrant the danger.
I do not want to ruin the fun, maybe something great will evolve from
this, but so far you did not convince me. If you are treating this as
an experiment, great, just don't be disappointed if it doesn't work
out. I think it wount.
Jenda
===== [EMAIL PROTECTED] === http://Jenda.Krynicky.cz =====
When it comes to wine, women and song, wizards are allowed
to get drunk and croon as much as they like.
-- Terry Pratchett in Sourcery
