something like if statement for assignation

Question

This is more like general question: Is there a way to assign a value like an if statement? I have a dictionary and I want to check if key exists and then assign. For example:

if((_attr.val = [self.dic objectForKey:@"name"]))

And i know that if key exist in _attr.val i will get object, if not i will get null. Great, but if statemant requires to_do_something after it, but in my case this is it - all what i want to do.

This is probably a silly question, but i'm having trouble with finding a solution.

I want to find something like ASSERT() known from c++.

I don't understand; you want to assign a value like an `if` statement but don't want to do the thing after the `if` statement? How about not using an `if` statement? — trojanfoe, Jul 06 '12 at 11:29

Rui Peres · Accepted Answer · 2012-07-06T11:54:45.027

1

The if makes sense when you want to create a conditional path. In this case you just want to assign the value to _attr.val, still you should check if everything went was you expected. I would go with:

_attr.val = [self.dic objectForKey:@"name"]
if(!_attr.val){
  // Conditional case for a nil value.
}

If it really doesn't matter the end result (either a value or nil) just go:

_attr.val = [self.dic objectForKey:@"name"]

Either way, if you started this question with the if in mind it seems that you want to make some sort of check.

With NSAssert:

_attr.val = [self.dic objectForKey:@"name"]
NSAssert(_attr.val,@"Value is nil");

edited Jul 06 '12 at 11:54

answered Jul 06 '12 at 11:30

Rui Peres

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And if the user compiles with `NS_BLOCK_ASSERTIONS`? – trojanfoe Jul 06 '12 at 11:35
No, the code will break because `_attr.val` won't be assigned, and user will have a hard time finding this bug using the code you have provided. – trojanfoe Jul 06 '12 at 11:44
You are right, if the `NSAssert`isn't allowed then the `attr.val` will be nil. So should the if be kept and the `NSAssert` out? – Rui Peres Jul 06 '12 at 11:46
I don't see an edit? But it should assign outside the `NSAssert()` and just check the value within the `NSAssert()`. – trojanfoe Jul 06 '12 at 11:51
Check now. if it's according to what you said. – Rui Peres Jul 06 '12 at 11:54
let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/13513/discussion-between-jacky-boy-and-trojanfoe) – Rui Peres Jul 06 '12 at 11:57

something like if statement for assignation

1 Answers1