c# Casting v As operator

[OriginalGriff]

B. I don't like to rely on exceptions for normal processing (they are slow and clumsy for that), so you have to check for null.

SomeObject obj = e as SomeObject;
if (obj != null)
{
...
}

While

if (e != null && e is SomeObject)
{
SomeObject obj = (SomeObject) e;
...
}

looks ugly. Plus, if you are going to use obj as a SomeObject instance, then the former is quicker since there is only one check on the type of e

Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together. Manfred R. Bihy: "Looks as if OP is learning resistant."

[jim lahey]

I'm with Ravi on this one.I use both, the decision if which one to use is purely based upon what I need to happen should it go wrong

[Sahir Shah]

He's doin it on purpose to annoy you Senhor Vilmos. I thought you would have figured that out by now :D

Und wenn du lange in einen abgrund blickst, blickt der Abgrund auch in dich hinein.

[Nemanja Trifunovic]

It is not about preference. When I want an exception in case of type error I use A., and if I want a null I use B. I don't see a point of something like:

SomeObj obj = e as SomeObject;
if (obj == null)
throw new InvalidCastException();

Of course, in good languages casting is almost always a sign of a design error.

utf8-cpp

[PIEBALDconsult]

Richard A. Dalton wrote:

Plug-in tpye code

I don't have such problems with plug-ins.

[PIEBALDconsult]

OriginalGriff wrote:

(they are slow and clumsy for that

No they're not.

[Mike Hankey]

I used to use A (C upbringing) now I kinda favor B.

I Haven't Gone To Bed With Any Ugly Women, but I've Sure Woke Up With A Few.

[PIEBALDconsult]

Depends on the situation. Mostly proper casting, as occasionally, particularly when checking for a derived type.

[Nagy Vilmos]

Don't mind if I do. :beer: yourself.

---

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[Sahir Shah]

Norm .net wrote:

The hand is quicker than the I eye

Too much hand is bad for the eye.

Und wenn du lange in einen abgrund blickst, blickt der Abgrund auch in dich hinein.

[PIEBALDconsult]

I use A and never get an Exception, what are you people doing? :confused:

[Nemanja Trifunovic]

PIEBALDconsult wrote:

what are you people doing?

SomeType obj = (SomeType)BloatedUglyUnreadableFrameworkFactory.CreateObject(someXMLStringThatIHopeWorksSometimesButNeverKnowForSure);

utf8-cpp

[Ennis Ray Lynch Jr]

As is for poor programmers. If you know that e always is SomeObject then e should be typed as such using some other method. Otherwise you always have to check the result of the as operation. So then you have the following two scenarios which must always be in case A or case B:

if(e is SomeObject){
SomeObject someObject = (SomeObject)e;
}

or

SomeObject someobject = e as SomeObject;
if(someObject != null){

}

But then in case by I always here the response ... but I know e is always SomeObject. Really then maybe it should be defined as such. The AS operator is designed solely to support developers that don't have a fundamental concept of type. After all, for all of the time I have seen the is operator used with a subsequent cast, checking for null after the AS is a white rhinoceros.

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[peterchen]

The first when I need the exception, the second when I need the null. Because face it, e is never what you need it to be.

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[Pete OHanlon]

Thanks Ennis - I'm a poor programmer then because I use as, rather than the double cast, which is doing the same work again. What happens internally with as is that it checks to see if the variable is of the type, and if it is it returns a non-null pointer to that type. With the is operator, you check to see if it is of the type and then you cast it - which still determines internally whether or not it belongs to that type (this is how it throws an InvalidTypeException). In any case where you are using code-discovery, such as IoC, then the as call is more efficient. [Edit]I should add that this relates to our plugin code where the client provides their own logic, and "forgets" to implement the appropriate interfaces.[/Edit]

Forgive your enemies - it messes with their heads

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modified on Thursday, June 23, 2011 9:30 AM

[Pete OHanlon]

You have better clients than we do then. You tell them, you must implement this interface in order for this to work, and bam they completely fail to implement the interface.

Forgive your enemies - it messes with their heads

My blog | My articles | MoXAML PowerToys | Mole 2010 - debugging made easier - my favourite utility

[Lost User]

peterchen wrote:

Because face it, e is never what you need it to be.

Not according to Pompey's review of his day at the races.

Every man can tell how many goats or sheep he possesses, but not how many friends.

[Sahir Shah]

Somebody didn't read the subject of the post.

Und wenn du lange in einen abgrund blickst, blickt der Abgrund auch in dich hinein.

[Jim Crafton]

You've been reading java code on the throne again haven't you? :)

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[NormDroid]

:wtf: are you going on about.

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