[CMake] BOOL type

[Pau Garcia i Quiles]

Quoting Bill Hoffman <bill.hoffman at kitware.com>:

> Mike Jackson wrote:
>
>>
>> I might kindly disagree. There are many instances where backward   
>> compatibility was broken in order to clean things up and move on.
>> Vtk 4.x to 5.x was one of those. My code broke with the 5.x release  
>>  BUT it was for the better. And more importantly I was given plenty  
>>  of notice that it was coming. The jump from 2.4 to 2.6 seems like  
>> a  good time to make the break and clean things up. As long as  
>> there  is a comprehensive list of breakage I don't think people  
>> will have  a real problem with it.
>>
>
> Sure, but when you moved from VTK 4.x to 5.x you got compile time
> errors.  If we change this, something will most likely silently fail.

What about doing the opposite of what Alex' patch did? What about  
making Y, YES, 1, ON synonyms? It's more or less what Brandon proposed  
but without introducing a BOOL(variable bool_value) command.

-- 
Pau Garcia i Quiles
http://www.elpauer.org
(Due to my workload, I may need 10 days to answer)