[cmake-developers] ExternalProject EXTRACT_COMMAND (was: New feature, git access)

[Pau Garcia i Quiles]

On Tue, Nov 26, 2013 at 4:26 PM, Brad King <brad.king at kitware.com> wrote:

The test fails for me with spaces in the path because you're writing
> the extraction command into the script without quoting so the spaces
> cause incorrect parsing at build time.  You can write it as
>
>  file(WRITE ... "
>  ...
>  set(extract_command "${extract_command}")
>  ...
>  ... COMMAND \${extract_command} ...
>  ...
>  ")
>
> so that the exact value of the command is stored in the script and
> expanded when evaluated at build time.  It is probably simplest to
> refactor the default extraction command to be written into the script
> in this way also.  Then you simply don't generate the default when an
> explicit command is passed.
>
>
 If I understand correctly what you mean, that would require either:
- Duplicating the test for extensions in both the extract-<target>.cmake
and the current location so that we can fail in CMake generation time if a
file we don't know how to extract is passed
 or
- Failing ("error: do not know how to extract...") only in compilation time

Or maybe I'm missing something?


The EXTRACT_COMMAND needs a way to have a placeholder for the file name
> so that the caller does not need to know where ExternalProject keeps
> the file after downloading.
>
>
Actually, the test was wrong: the filename is automatically appended to the
end. I. e. EXTRACT_COMMAND is exactly that: the command, not the command +
filename:

EXTRACT_COMMAND ${CMAKE_COMMAND} -E tar xvf

not

EXTRACT_COMMAND ${CMAKE_COMMAND} -E tar xvf /path/to/file


However, the placeholder could prove useful if the filename needs to go in
the middle of the EXTRACT_COMMAND. Do you have any suggestion of should I
make something up, like, say, >#< ?

I am attaching a new patch, which fixes the path-with-spaces issue. No
placeholder has been implemented yet.


> I don't understand the "...After you have been invited..."
> > in http://www.cmake.org/Wiki/CMake/Git/Account#Git
> > (who would know I need an invitation!?)
>
> The sentence immediately preceding that says  "See our new maintainer
> instructions to join" and has a link to the instructions.  They have
> a step for posting to this list for discussion.  We invite productive
> contributors for direct access in due time.
>
>
My bad :-) I visited the link, read the instructions but on step 4 I was
only reading until "Subscribe to the CMake Developers Mailing List". As I
was already subscribed, I didn't look any further O:-)

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