Manual page generation

[mmakowski]

Manual page generation from command list defined in Main. Based on the approach and implementation in darcs.

Fixes #848.

[23Skidoo]

Thanks! Looks good on a first glance.

[23Skidoo]

Looks like this duplicates the functionality of CommandType in D.S.Command.

[23Skidoo]

LGTM but I'd like to see some parts moved to D.S.Command.

[23Skidoo]

A potential future improvement may be to add support for generating per-command manpages (e.g. cabal manpage install). Then we could make cabal help display a manpage when run from the terminal, a-la git help.

[23Skidoo]

FYI, there are also some formatting problems (but I don't see them as impediment for merging):

[mmakowski]

@23Skidoo, thanks for the review. I will try to address the comments over the next couple of days.

Regarding cabal manpage install, I think that woud require making manpage a library-level special command similar to help. In the existing implementation I tried to confine the manpage concerns to cabal-install. It is still not clear to me which functionality belongs in the library and which in the command-line app, for example I find it surprising that help formatting is a library concern.

Another thing to consider with help displaying manual pages is that man is not availabe on Windows. IIRC git deals with it by making help open a browser pointing to online man page, I'm not sure if that is preferable to showing help in the console.

[23Skidoo]

Regarding cabal manpage install, I think that woud require making manpage a library-level special command similar to help.

I am not so sure. If you can generate a manpage with information about all commands from cabal-install, it should also be possible to do the same for a single command (maybe after some refactoring of D.S.Command).

Code for help formatting and option handling lives in the Cabal lib because we want to support things like ./Setup foo --help. I think that manpage generation belongs in cabal-install.

Another thing to consider with help displaying manual pages is that man is not availabe on Windows.

In these cases we can just revert to the old mode of output.

[mmakowski]

I have now moved command-related bits to D.S.Command and fixed formating of sandbox sub-commands.

[23Skidoo]

LGTM now.

[23Skidoo]

Merged, thanks!