#26 Subcommands

[Federico Ciuffardi]

I can't find an easy way to implement subcommands (similar to how it's done in git).

There is this question on stackoverflow but I don't know if the OP was able to contact you.
https://stackoverflow.com/questions/25083814/c-cli-subcommands-with-tclap

For now I'm achieving it in the following way:

• I defined:

  • An UnlabeledValueArg to recognize the subcommand

  • An then an UnlabeledMultiArg to recognize the args of the subcommand

  • Then I parse the vector resulting of prepending the subcommand to the subcommand args with another subcommand-specific CmdLine

• There is a problem if you want to have a help for the command and also one for the subcommand (as you can do in git), the --help flag is parsed as part of the command even if it is after the UnlabeledValueArg with which the subcommand is recognized. For now I fix this by:

  • Attaching an IgnoreRestVisitor to the UnlabeledValueArg that the subcommand was recognized with (see https://sourceforge.net/p/tclap/bugs/39/).

  • Then I require a function that allows not to ignore in the next parse, since it does not exist, I implement it in an analogous way to Arg::beginIgnoring()

Note: The last problem not only happens with --help but it can happen with other flags that exist both in a command and in a subcommand.

Please let me know if you can think of a better way to do this. Or if I can help with something.

Thanks!

[Daniel Aarno]

Thanks for the feedback, and sorry for the delay - I was traveling. I responded to the OP on SO, but here it is for posterity:

This isn't really part of the design of TCLAP. It's focused on providing "POSIX style" command line flags/arguments, which was the style of the day. It would probably not be too difficult to provide a git-style parser in the same spirit of TCLAP, but as of now TCLAP is probably to wrong tool for the job.