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Re: Undefine mixed data

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March 17, 2023 20:58
Re: Undefine mixed data
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Marton, I am not sure of your meaning.  I took the warning message as:

    For Scalars assign a Nil, for Arrays/Hashes/Etc. use Empty or ().

Because you might be read as suggesting "@ary = Nil should undefine @ary";
I will point out that will conflict with:

    @a = Nil;

which is defined to assign the RHS entry to the first element of @a.
I suspect there is no way to destroy a container but to smash it into
a scope wall.

Some day I shall get serious about understanding Raku's containers.
In the meantime, I'll just keep creeping up on them and observing.


On Tue, Mar 14, 2023 at 01:38:22PM +0100, Polgár Márton wrote:
> On 2023. 03. 14. 4:42, rir wrote:
> >      undefine seen at:
> >        <unknown file>, line 1
> >      Will be removed with release v6.e!
> >      Please use another way: assign a Nil; for Arrays/Hashes, assign Empty or () instead.
> > 
> > Will that deprecation require a conditional and two assignments
> > for mixed data?
> > 
> > [$a, @a, $b, %c, $c, &d].map: { .&undefine};
> > 
> > [$a, @a, $b, %c, $c, &d].map(
> >      { $_ = $_ ~~ (Associative,Positional).any ?? Empty !! Nil });
> And even those ways don't seem too convincing... after all, it's more a
> question of containerization if assigning Nil will cut it or not. I didn't
> know about undefine but it appeared to me as an issue that you can just
> assign Nil to an Array and get something that is not the default value -
> moreover, it doesn't even evaluate to boolean False!
> It seemed like something that can wait and that could cause a lot of
> friction as a breaking change but I think it would make overwhelmingly more
> sense to make Nil always set the default. It is a special value of a special
> singularity type on its own; it's questionable whether it should ever appear
> as an assigned element of a composite container but to make it STORE in a
> special, resetting way, seems kind of a no-brainer, apart from the
> "breakage"...

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