conversion error on multiple bool flagse

[lambdafu]

When using a bool flag, giving the option multiple times on the command line causes a conversion error (because it can not count the number of times the option appears in a bool variable, I presume).

But that error message is ugly and user-unfriendly, so why would anybody ever use that? Which means everybody will just use an int and check for == 0.

Why not just keep the value at true and ignore the extraneous appearances of the bool flag on the command line?

Test case is in AppTest.cpp:156:

    args = {"-b", "-b"};
    EXPECT_THROW(run(), CLI::ConversionError);

[henryiii]

My (original) thinking is that int means multiple flags and bool one; you could then do: if(flag) to see if there are one or more. However, I think you are probably right. It's uncommon to want multiple flags to fail, and custom logic could be added to the int versions or the callback version.

[lambdafu]

The way this works in GNU projects is that sometimes there is a corresponding --no-FLAG option that sets it to false, and the last one of --foo, --no-foo on the command line wins.

[lambdafu]

Yep, #38 works.