Multiple commands problem - use one_of instead of |

[WojciechMigda]

Hi,

some time ago I stumbled upon a problem with CLI, which consisted of three or more commands. I have found a work-around and I am posting it here hoping it will help others struggling with the same.

The smallest non-working example is:

    auto cli = (
        command("a").set(m.a) |
        command("b").set(m.b) |
        (
            command("c").set(m.c) & value("i", m.i)
        )
    );

where clipp would parse a, b, but not c 123.

It turned out that I can make clipp do what I want if instead of specifying the alternative of commands with | I'd use clipp::one_of.
The example above becomes:

    auto cli = one_of(
        command("a").set(m.a),
        command("b").set(m.b),
        command("c").set(m.c) & value("i", m.i)
    );

The docs, unless I am missing something, specify that one_of is the same as |, yet they produce different usage lines. The first one gives

((a|b) | (c <i>))

while the second one

(a | b | (c <i>))

[thomthom]

Ah! I ran into the same issue (Thank you for posting a solution to it).

I had this:

  auto cli = (
    (
      install_mode |
      list_mode |
      fetch_mode |
      remove_mode |
      reset_mode |
      help_mode
    ),

    option("-v", "--version").call(ShowVersion).doc("show version")
  );

I needed to change it to this for things to work as I wanted it to:

  auto cli = (
    one_of(
      install_mode,
      list_mode,
      fetch_mode,
      remove_mode,
      reset_mode,
      help_mode
    ),

    option("-v", "--version").call(ShowVersion).doc("show version")
  );

Is this a documentation issue or an issue related with how the | operator works?

[WojciechMigda]

AFAIR the implementations differ between the two, and the | operator implementation is not commutative.