single named param

[Gaal Yahas]

I was writing tests for signatures and came across this ambiguity:

:(:$x)

Does this mean a single named parameter called $x, or a default invocant
and a single required positional named $x?

--
Gaal Yahas <ga...@forum2.org>
http://gaal.livejournal.com/

[Gaal Yahas]

On Tue, Sep 12, 2006 at 06:46:50PM +0800, Audrey Tang wrote:
> >Does this mean a single named parameter called $x, or a default invocant
> >and a single required positional named $x?
>

> "A default invocant" prolly doesn't make sense there... There's
> nothing to "default" to. :-)

What invocant is constructed in this signature then?

method foo ($just_a_named_param)

Is the signature for &foo really the same as that of bar?

sub bar ($just_a_named_param)

I was sort of assuming you could tell by a signature if it was for a
method or a sub.

[Audrey Tang]

2006/9/12, Gaal Yahas <ga...@forum2.org>:

> Does this mean a single named parameter called $x, or a default invocant
> and a single required positional named $x?

"A default invocant" prolly doesn't make sense there... There's

nothing to "default" to. :-)

Audrey

[Larry Wall]

On Tue, Sep 12, 2006 at 01:59:23PM +0300, Gaal Yahas wrote:

: On Tue, Sep 12, 2006 at 06:46:50PM +0800, Audrey Tang wrote:
: > >Does this mean a single named parameter called $x, or a default invocant
: > >and a single required positional named $x?
: >
: > "A default invocant" prolly doesn't make sense there... There's
: > nothing to "default" to. :-)
:
: What invocant is constructed in this signature then?
:
: method foo ($just_a_named_param)
:
: Is the signature for &foo really the same as that of bar?
:
: sub bar ($just_a_named_param)

Maybe methods and submethods turn

method foo ($just_a_named_param)

into

method foo ($ : $just_a_named_param)

Since we regularized invocants, there's much less need for an empty
invocant, so maybe the $ is required there if you put the :. If so, we
should probably explicitly say that there are no variables of the form
"$:", "$;", or "$,", so those will always be taken as "$ :", "$ ;", and
"$ ," respectively. At least within signatures.

In any case, prefix ':' is not an operator. In :(:$foo) the :$
starts a token, so you'd have to put space between to mean :(: $foo).

: I was sort of assuming you could tell by a signature if it was for a
: method or a sub.

I'm trying to decide if

sub ($self: $just_a_named_param)

can meaningfully put anything into $self. It seems doubtful, and it should
probably be

submethod ($self: $just_a_named_param)

So for the jet-lagged moment I think your assumption is valid. I might
jet-delag at any moment, however...

Larry

[Mark Stosberg]

Larry Wall wrote:
>
> I'm trying to decide if
>
> sub ($self: $just_a_named_param)
>
> can meaningfully put anything into $self. It seems doubtful, and it should
> probably be
>
> submethod ($self: $just_a_named_param)

I agree. If

sub ($self: $foo)

works than it reduces privacy, since someone could call a sub like
externally, when it wasn't intended.

Mark

[Audrey Tang]

在 Sep 12, 2006 6:59 PM 時，Gaal Yahas 寫到：

> What invocant is constructed in this signature then?
> method foo ($just_a_named_param)
>
> Is the signature for &foo really the same as that of bar?
>
> sub bar ($just_a_named_param)

As Larry said, they shouldn't be the same; the first one is

&foo.signature === :($ : $just_a_named_param);

The second one is:

&bar.signature === :($just_a_named_param);

> I was sort of assuming you could tell by a signature if it was for a
> method or a sub.

That's correct; the "method" keyword augments the signature with an
unnamed
"$" invocant if it's not explicitly specified. (In Pugs.Val.Code
terms, that's nullID for
both the p_label slot and (v_name . p_variable).)

Cheers,
Audrey