#816: PMC 'Undef' does not support logical_not
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Reporter: Austin_Hastings | Type: bug
Status: new | Priority: normal
Milestone: | Component: core
Version: 1.3.0 | Severity: medium
Keywords: | Lang:
Patch: | Platform:
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Comment(by bacek):
Replying to [ticket:816 Austin_Hastings]:
> This code in Close:
> {{{
> ok(!(o.flat()), "flat: New object (undef flat) is false");
> }}}
> compiles to:
> {{{
> $P51 = o."flat"()
> not $P52, $P51
> "ok"($P52, "flat: New object (undef flat) is false")
> }}}
> And then fails, with:
> {{{
> logical_not() not implemented in class 'Undef'
> }}}
Undef.logical_not was implemented in r41259.
> Grepping for logical_not in *.pmc gives back only scalar.pmc.
>
> * While I know that Perl's Undef has 0/nil/false/"" behavior, is that
right for Parrot? (To what extent is Undef just a safe Null?)
No. Undef is not "safe Null". Undef is something declared but not defined.
Null is undeclared at all.
> * Should there even be a 'not' opcode? We've got isfalse.
Some weird languages can have semantic of "Foo == !Foo" :)
> * Should other pmc types be implementing logical_not?
Not all of them. But all scalar types probably should.
> * Should Undef be a subclass of scalar, and so inherit?
It's actually really good idea from my point of view. I would recommend to
open "RFC ticket" with this proposal.
--
Bacek
--
Ticket URL: <https://trac.parrot.org/parrot/ticket/816#comment:1>
Parrot <https://trac.parrot.org/parrot/>
Parrot Development
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