[CMake] Proper options with cmake

[Rolf Eike Beer]

Gennadiy Rozental wrote:
> Hi,
> 
> How do I implement a proper option with default value. Both boolean and
> string.
> 
> If I define option like this:
> 
> option( GOO "descr" OFF )
> 
> here is what happends:
> 
> 1. First time I run cmake without specifying GOO, GOO is OFF
> 2. Any time I run cmake with -DGOO=ON, GOO is ON
> 3. Any time I run cmake with -DGOO=OFF, GOO is OFF
> 4. Any time after the first I run cmake without specifying GOO, GOO is the
> same as it was in previous run, not necessarily OFF.
> 
> My problem is semantic of (4). What I want is for GOO to have default value
> I specified if one was not provided, regardless of what was the value of GOO
> in previous run. This seems like such an obvious expectation, that I do not
> understand why it is not the case now.

That is the sense of option(): provide a persistent choice.

What you want sounds like:

if(NOT DEFINED GOO)
  set(GOO Off)
endif()

Eike
-- 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 198 bytes
Desc: This is a digitally signed message part.
URL: <http://www.cmake.org/pipermail/cmake/attachments/20130625/d9e2f619/attachment.pgp>