[cmake-developers] if (FOO == BAR) ...

[David Cole]

I know. I understand your motivation, and that the present state of 
affairs is less than desirable.

However, I still object to your patch on two grounds:

(1) Using the name "==" implies that it is doing an equivalence 
comparison, similar to C / C++, where the same named operator may be 
used with multiple types of left and right hand sides.

If we had it in CMake, one *should* logically be able to infer that any 
type of comparison would be possible: string, variable, int or float 
numbers, versions. But that wouldn't be true, and so people would have 
to re-learn their intuition about == and it would just be strange for 
almost everyone.

(2) We already have 2 ways of doing EQUAL comparisons, and this would 
be a 3rd, without being complete, and without eliminating either of the 
other ways...

This 3rd way, while having the nice feature of doing what you want 
w.r.t. string values, and not doing variable value lookup, would ADD to 
the confusion still more because it is counter-intuitive as noted above.

Sorry, I just don't see this as a good addition overall.


David



-----Original Message-----
From: Alexander Neundorf <neundorf at kde.org>
To: cmake-developers <cmake-developers at cmake.org>
Sent: Sun, Mar 24, 2013 5:23 am
Subject: Re: [cmake-developers] if (FOO == BAR) ...


On Saturday 23 March 2013, David Cole wrote:
> Wow, could be a variable on the right, too. So my previous example was
> still not 100% safe.
>
> Maybe this construct is 100% safe:
>
>     set(x "${some_var_that_may_eval_to_another_var_name}")
>     set(y "some string constant that may also accidentally be a var")
>     if(x STREQUAL y)
>
> You can see why the "x${var}" STREQUAL "xSomeString" approach is
> appealing after a discussion like this.

Hmm, actually, to me, no.
Now you have ugly code and as Brad noted, you can still construct cases 
where
it breaks.
That's why I came up with that quick, safe and not-really-dirty patch.

Having said that, I've never been hit by that problem, or at least I'm 
not
aware of it.

Alex
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