[CMake] How to find the DLL's a a required package searched with FIND_PACKAGE()?

[Arjen Markus]

On 2010-02-11 01:20, David Cole wrote:
> On Wed, Feb 10, 2010 at 7:16 PM, Alan W. Irwin 

> 
>     Would setting that environment variable from cmake affect subsequent
>     Windows
>     builds?  I don't have any Windows development experience, but this
>     question
>     just came up on the PLplot list. There, we all speculated from our
>     various
>     Linux and Windows platform perspectives that SET(ENV{PATH} ...) just
>     sets
>     the PATH when you are running cmake and would have no effect on the
>     environment for the subsequent build.  Thus, we thought you would
>     have to
>     externally set the PATH before running the build.  But we all could
>     be wrong
>     which is why I have asked this question.  :-)
> 
> 
> Alan,
> 
> You are correct. Doing this...
> 
> SET(ENV{xxx} "value")
> 
> ...in a CMakeLists.txt file only sets an environment variable for the 
> duration of the cmake run. It has no influence on downstream build steps.
> 

The story with environment variables on Windows is slightly more
complicated than that:
- On Linux/UNIX you can set environment variables for the duration of
   a shell process via the set (setenv) command and by putting such
   commands in a shell script and using . (or source) to run the
   script in the same shell. This does not happen if you run the
   shell script normally (as it is run in a separate process then).

- On Windows (or DOS if you want to include some history) there is
   no separate "source" command. Instead if you set an environment
   variable in a batch file and run that batch file in a DOS-box,
   it will keep that value even after the batch file has finished -
   the batch file is run in the same process (an exit statement in
   such a batch file exits the DOS-box!). If you run a separate
   program, changes to the environment will be lost, just as under
   Linux.

For building PLplot under Windows I extend the path first (so that
includes the directory where the DLLs will be found) and then
run the various commands (CMake and make and the examples). But
that has become an "automatism".

What you could do is wrap the CMake command in a batch file,
including the command "set path=..." and run that instead.

The drawback is that the path will be expanded each time
you run it.

Regards,

Arjen