allow dash in catkin package names

[dirk-thomas]

Replaces #182.

[gavanderhoorn]

@dirk-thomas wrote (in #182):

I just hope we will not run into the problem of duplicate package names afterwards or uncertainty about how the CMake variables are being exported (since that was a main reason why this rule enforced uniqueness and consistency).

can you say anything about the exported CMake variables? Would the dashes be retained there?

[dirk-thomas]

can you say anything about the exported CMake variables? Would the dashes be retained there?

CMake variables can't contain dashes.

[gavanderhoorn]

CMake variables can't contain dashes.

exactly, so will the variables for those pkgs have underscores instead then? Is that the potential confusion you are referring to?

[dirk-thomas]

so will the variables for those pkgs have underscores instead then? Is that the potential confusion you are referring to?

Yes, I would assume using underscores would be a reasonable mapping.

A package name with dashes is more common for e.g. Python packages though. I hope this won't be used for CMake packages often.

[dirk-thomas]

@ros-infrastructure/ros_team Please review.

[wjwwood]

CMake variables can't contain dashes.

Actually that's not true (/shudder) 🤢:

william@johnnycake /tmp
% cat test.cmake
set(a-dash "Hello World!")
message(STATUS ${a-dash})

william@johnnycake /tmp
% cmake -P test.cmake
-- Hello World!

[dirk-thomas]

CMake variables can't contain dashes.

Actually that's not true (/shudder) 🤢:

Interesting, that is the first time I have seen that but the docs "agree" with it.