String -> Numeric conversion
Luke Palmer
> Date: Wed, 6 Nov 2002 14:53:37 -0800
> From: Michael Lazzaro <mlaz...@cognitivity.com>
> X-SMTPD: qpsmtpd/0.12, http://develooper.com/code/qpsmtpd/
>
>
> If anyone knows the answer to these two questions, I'd appreciate it.
>
> 1) What do these do?
>
> my int $n = 5; # OK
> my int $n = 5.005; # trunc or err?
Trunc. Int context, you know :)
> my int $n = "5.05ff" # 5, 0, undef, NaN, or exception?
If it's like Perl5, 5.05. But there could be reason to make it an
exception. Dunno on that one. I would say 5.05 for now, until
someone with authority corrects it.
> my int $n = "fdsjfdf" # 0, undef, NaN, or exception?
Likewise here. There could also be reason to have this behave
differently from the last one. Though, I would say 0 for now.
>
> 2) Do "num" and "int" share a common base "is a number" class, such
> that (in perl5-ish speak) we can say
>
> if want(numeric) { ... }
>
> to identify both, or is "num" the base class to test for, and "int" a
> subclass? (I'm pretty much assuming "bit" is a number too, but never
> mind that now.)
I believe this was the plan. Remember, there was int context and num
context, so a natural extension would be that conclusion.
As for your documentation plan, I think it's a good idea, though I
concur with Dan on Just Do It. Document the language for what best
makes sense now. If there are *big* issues, ask Larry et al. on this
list. For the little ones, use common sense and they will be hashed
out later.
Luke
Michael Lazzaro
If anyone knows the answer to these two questions, I'd appreciate it.
1) What do these do?
my int $n = 5; # OK
my int $n = 5.005; # trunc or err?
my int $n = "5.05ff" # 5, 0, undef, NaN, or exception?
my int $n = "fdsjfdf" # 0, undef, NaN, or exception?
2) Do "num" and "int" share a common base "is a number" class, such
that (in perl5-ish speak) we can say
if want(numeric) { ... }
to identify both, or is "num" the base class to test for, and "int" a
subclass? (I'm pretty much assuming "bit" is a number too, but never
mind that now.)
I know that this has been covered before, way back, but my memory fails
me. Just trying to polish up what I wrote.
MikeL
Piers Cawley
>> Mailing-List: contact perl6-lan...@perl.org; run by ezmlm
>> Date: Wed, 6 Nov 2002 14:53:37 -0800
>> From: Michael Lazzaro <mlaz...@cognitivity.com>
>> X-SMTPD: qpsmtpd/0.12, http://develooper.com/code/qpsmtpd/
>>
>>
>> If anyone knows the answer to these two questions, I'd appreciate it.
>>
>> 1) What do these do?
>>
>> my int $n = 5; # OK
>> my int $n = 5.005; # trunc or err?
>
> Trunc. Int context, you know :)
>
>> my int $n = "5.05ff" # 5, 0, undef, NaN, or exception?
>
> If it's like Perl5, 5.05. But there could be reason to make it an
> exception. Dunno on that one. I would say 5.05 for now, until
> someone with authority corrects it.
>
>> my int $n = "fdsjfdf" # 0, undef, NaN, or exception?
>
> Likewise here. There could also be reason to have this behave
> differently from the last one. Though, I would say 0 for now.
Well, it's restricted to either 0 or an exception since you can't use
an int to store anything else (like, for instance the PMCs associate
with either undef or NaN).
Hmm, what does
NaN.isa('Number')
return?
--
Piers
"It is a truth universally acknowledged that a language in
possession of a rich syntax must be in need of a rewrite."
-- Jane Austen?
Damian Conway
>
> If anyone knows the answer to these two questions, I'd appreciate it.
Only Larry "knows". But I'm prepared to take an educated guess.
> 1) What do these do?
>
> my int $n = 5; # OK
Yes.
> my int $n = 5.005; # trunc or err?
Truncate to 5 with optional warning (would be my preference).
> my int $n = "5.05ff" # 5, 0, undef, NaN, or exception?
Truncate to 5 with optional warning (would be my preference).
> my int $n = "fdsjfdf" # 0, undef, NaN, or exception?
Call C<fail> would be my preference.
That is, let the user decide whether the result is C<undef> or an exception.
> 2) Do "num" and "int" share a common base "is a number" class, such that
> (in perl5-ish speak) we can say
>
> if want(numeric) { ... }
>
> to identify both, or is "num" the base class to test for, and "int" a
> subclass?
The latter would be my expectation. Though it's C<Num>, not c<num>, I believe.
Damian