Hi all,
I raised some concerns over catkin_make convenience in a meeting, here
are the results of the brainstorming. catkin_make is mostly a
convenience wrapper to cmake/make, for usage with the catkin build
system starting with ROS Groovy.
The current catkin_make design was guided by the desire to have a
consistent and self-explaining workspace layout for tutorials and novice
users, a quick way to create workspaces, and a wrapper around cmake to
reduce cumbersome typing of common -D options.
In it's current state, catkin_make may not as convenient as it could be.
Current quirks are:
- the workspace/src folder in itself is not popular with everybody
- it is inconvenient to have to cd into the workspace folder to invoke
catkin_make
- it is inconvenient that wstool commands work in the src folder and
below only, currently, meaning another "cd" step
- invoking catkin_make once with custom options (for build/src
locations), and then again without options does not remember the last
options, and retyping the options is also cumbersome.
- cleaning up builds (make clean, make distclean) does not work too well
and is cumbersome, more support would be nice
Since REP128 (
http://ros.org/reps/rep-0128.html) does not make a strong
effort to justify the design it defines, we have to also look at some
use cases and find justifications.
- We can consider 3 types of user groups who may want to use catkin_make
-- total noobs: Those need one source space, one build configuration and
that's it
-- advanced programmers: Those may typically have 2 build
configurations, one with debug settings, one with performance optimized
settings
-- power users: Those may have a large number of build configurations
for the same workspace, for cross compilation experiments and such
I assume the toplevel "src" folder allows to have some cleanliness in
particular for power users, having multiple build, devel and install
spaces at the workspace root level, and packages one level below. On the
other hand, I assume it would be similarly clean if all build, devel and
install spaces were stored away in workspace/builds, and packages else
reside in the workspace root.
- catkin workspaces are used by several people using symbolic linking
(for convenience, and maybe due to known limitations of catkin overlaying)
- catkin also does env_caching, which needs to be taken into account for
sequences of buildspace creation actions
- there is also catkin_make_isolated, which currently creates a
different folder layouts, maybe some consolidation could happen there as
well
So some design strategies that we came up with regarding more
flexibility of invoking catkin_make and setting up workspace layouts
according to personal preferences.
Alternative "Marker-file":
This idea involves placing a marker file at the workspace root, which
can be used by catkin_make as point of reference when invoked in a
subfolder (and maybe also by roscd without arguments). To support
invoking catkin_make without arguments with custom paths, the marker
file could have content that defines build configurations, e.g. the last
one that was specified. For users that typically have multiple build
configurations, this could be extended to have differently named
configurations. Probably cmake already caches options for us, so really
what could be stored in the marker file would be the path to a build
space. However build-spaces get nuked regularly (since we have no great
"clean" target), so duplication of information might still make sense in
the marker file (unless we find a nice "clean" command).
Such a markerfile might also be made compliant with wstool, one way or
the other. The disadvantage here is that some additional infrastructure
is require, to be maintained.
Alternative "Build Env Switching":
This idea involves switching build configurations (rather than
workspaces), meaning every build folder gets it's own file to source,
like "setup.sh", though a different name might be better. Such a file
would declare an env variable pointing to the build folder, and invoking
catkin_make from anywhere would invoke cmake/Make in the folder of the
env var (if set). Disadvantages are that this is less transparent to the
user, requires the user to know about this setup file as well, and
encourages the bad habit of reusing the same shell for different build
environments.
So this is just brainstorming, and anyone who feels passionately enough
about catkin_make is welcome to contribute ideas, opinions, (informal)
votes. The next steps could be to write prototypes and a REP. Once we
start doing that, we'll probably take the discussion to the ROS
Buildsystem SIG, but I'd be happy to get some feedback by mere catkin users.
-- Thibault
PS: Some background discussion and ideas also here:
https://github.com/ros/catkin/issues/325
https://github.com/ros/catkin/issues/304
http://ros.org/reps/rep-0128.html
https://github.com/tkruse/rep/blob/rep0130/rep-0130.rst
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