August 18, 2005
Hi,

How can I test to see if a variadic parameter is null?

I don't think something like:

if (va_arg!(void*)(_argptr) == null) printf("Null");

Is safe.

Thanks,
--AJG.


August 18, 2005
"AJG" <AJG_member@pathlink.com> wrote in message news:de0p3i$q1p$1@digitaldaemon.com...
> Hi,
>
> How can I test to see if a variadic parameter is null?
>
> I don't think something like:
>
> if (va_arg!(void*)(_argptr) == null) printf("Null");
>
> Is safe.

Why wouldn't it be?  Casting to a void* is safe, since you can't read or write it.


August 18, 2005
Hi,

>> How can I test to see if a variadic parameter is null?
>>
>> I don't think something like:
>>
>> if (va_arg!(void*)(_argptr) == null) printf("Null");
>>
>> Is safe.
>
>Why wouldn't it be?  Casting to a void* is safe, since you can't read or write it.

What if it's a short, or a class, or something else other than an actual pointer, would it still work?

Thanks,
--AJG.



August 18, 2005
"AJG" <AJG_member@pathlink.com> wrote in message news:de0sv9$sj3$1@digitaldaemon.com...
> Hi,
>
>>> How can I test to see if a variadic parameter is null?
>>>
>>> I don't think something like:
>>>
>>> if (va_arg!(void*)(_argptr) == null) printf("Null");
>>>
>>> Is safe.
>>
>>Why wouldn't it be?  Casting to a void* is safe, since you can't read or write it.
>
> What if it's a short, or a class, or something else other than an actual pointer, would it still work?
>
> Thanks,
> --AJG.
>
>
>

Check that the TypeInfo of the parameter subclasses TypeInfo_Pointer. That way you'll know the parameter isn't actually a short or a class reference. TypeInfo_Pointer is defined in object.d which is automatically imported so it is always available.

Note I haven't actually tried this - I just assume the typeid of a pointer subclasses TypeInfo_Pointer otherwise why have something called TypeInfo_Pointer :-P


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