[CMake] Forwarding parameters to cmake through cmake-gui

[David Cole]

> -----Original Message-----
> From: physhh . <physhh at gmail.com>
> To: Matthew Woehlke <matthew.woehlke at kitware.com>
> Cc: CMake ML <cmake at cmake.org>
> Sent: Fri, Nov 1, 2013 8:19 pm
> Subject: Re: [CMake] Forwarding parameters to cmake through cmake-gui
>
> The question is: What is the expected behavior?
>
> Execute it per configure but don't overwrite variables? What if one 
really wants to overwrite?
>
> Execute it once every time the binary directory changes? Changing 
stuff only through setting the path is bad.
>
> Other possiblities?

ccmake and cmake-gui are interactive programs meant to prompt the user 
to fill in the cache values properly before typing 'c' or clicking 
'Configure'.

-D is a convenient way to give cache values an initial value that is 
different from their natural 'default' values.

Using -D with ccmake and cmake-gui makes total sense, but it should 
only be used by the program to set the initial value that users see in 
the UI. After that point, the user should be in charge, and if he sets 
something different in the UI, the user value should win.

I think Matthew's bug report is correct: the UI value should be used 
and then stored in the cache for subsequent runs. The -D values to 
ccmake and cmake-gui should only be used for initializing UI entries. 
Therefore, they should *NOT* be passed to the internal CMake instance 
used for configuring.


HTH,
David