[Proposal] Option "-k" to keep source

[HashNuke]

Inspired by ruby-build's -k option.

Passing this option should uncompress and compile the package in ~/.asdf/sources/<plugin>/<version> instead of the tmp dir. This is plugin specific.

asdf install ruby 2.3.0 -k

• If -k is passed the plugin's install script is passed a source-compile path as another argument.
• The plugin's install script uses a temp or the source-compile path to compile the package depending on the option passed.

Atleast for now, this would make it possible to use gdb with ruby. I have this work-in-progress in the keep-source branch.

[HashNuke]

keep-source support is now in the keep-source branch of asdf and asdf-ruby.

• https://github.com/asdf-vm/asdf/tree/keep-source
• https://github.com/asdf-vm/asdf-ruby/tree/keep-source

Setting KEEP_SOURCE=1 when installing a ruby will preserve the source in ~/.asdf/sources/ruby/<version>

This helped with using ruby with gdb. If I can get getopt working with bash, I'll send a PR after adding the -k option.

EDIT: Comment originally posted from phone. Updated markup.

[danhper]

Nice! I think this would make sense for Python too, I will add the option to my plugin when you are done here!

[jayvdb]

I think this should actually be the default, and another command is added to cleanup unneeded source & build dirs.

e.g. I just installed Python, but I didnt have sqlite3-devel installed, resulting in

Downloading Python-3.6.7.tar.xz...
-> https://www.python.org/ftp/python/3.6.7/Python-3.6.7.tar.xz
Installing Python-3.6.7...
WARNING: The Python sqlite3 extension was not compiled. Missing the SQLite3 lib?

After installing the devels, asdf needs to refetch everything, and rebuild everything, which is wasted bytes and time.