Is there a way to have a runtime class check other than
if(cast(X)y)
( It just does not look really "nice" to me ^^)

funog wrote:
> Is there a way to have a runtime class check other than
> if(cast(X)y)
> ( It just does not look really "nice" to me ^^)
> 

Unless you are not going to use it as the type you are checking for what's wrong with that (or this)

if(auto x = cast(X) y)
{
 // use x
}

BCS Wrote:

> funog wrote:
> > Is there a way to have a runtime class check other than
> > if(cast(X)y)
> > ( It just does not look really "nice" to me ^^)
> > 
> 
> Unless you are not going to use it as the type you are checking for what's wrong with that (or this)
> 
> if(auto x = cast(X) y)
> {
>   // use x
> }

You are right, it's nice. But i guess it means the answer to my question is "no" ;)

funog wrote:
> BCS Wrote:
> 
>> funog wrote:
>>> Is there a way to have a runtime class check other than
>>> if(cast(X)y)
>>> ( It just does not look really "nice" to me ^^)
>>>
>> Unless you are not going to use it as the type you are checking for what's wrong with that (or this)
>>
>> if(auto x = cast(X) y)
>> {
>>   // use x
>> }
> 
> You are right, it's nice. But i guess it means the answer to my question is "no" ;)

Not strictly speaking, but certainly nothing more elegant.  You could presumably, for example, compare the .classinfo referances -- if (y.classinfo is X.classinfo) -- but... ew.  :)

-- Chris Nicholson-Sauls

Chris Nicholson-Sauls wrote:
> funog wrote:
>> BCS Wrote:
>>
>>> funog wrote:
>>>> Is there a way to have a runtime class check other than
>>>> if(cast(X)y)
>>>> ( It just does not look really "nice" to me ^^)
>>>>
>>> Unless you are not going to use it as the type you are checking for
>>> what's wrong with that (or this)
>>>
>>> if(auto x = cast(X) y)
>>> {
>>>   // use x
>>> }
>>
>> You are right, it's nice. But i guess it means the answer to my question is "no" ;)
> 
> Not strictly speaking, but certainly nothing more elegant.  You could presumably, for example, compare the .classinfo referances -- if (y.classinfo is X.classinfo) -- but... ew.  :)
> 
> -- Chris Nicholson-Sauls

Amusing anecdote: when I first started using D, I was under the impression that cast(T) would throw an exception if the cast couldn't be done.  So, off I went to write an instanceof function.

A few days later, I had this hideous piece of code that went and walked the object's inheritance tree to find out if it could be cast to the given type.

Almost immediately after I finished, I read something on the NG that pointed out that cast(T) simply returns null if the cast failed. Fiddlesticks.

Morale of this story: read the docs before you go assuming things :3

	-- Daniel

-- 
int getRandomNumber()
{
    return 4; // chosen by fair dice roll.
              // guaranteed to be random.
}

http://xkcd.com/

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