Default arguments break word-wrapping.

[Peter Simons]

The attached example program demonstrates the problem.

[anonymous]

Run to see the broken help output.

[Vladimir Prus]

Please specify how the produced output differs from expected output, and why you expect the output you expect.

[Peter Simons]

With Boost 1.37.0, the attached program generates the following output:

$ g++ test.cpp -lboost_program_options && ./a.out
| Supported options:
|   --help                          this is a sufficiently long text to requ
|                                   ire word-wrapping

Look closely at the description of the "--help" option. You'll find that word-wrapping is performed in the middle of the word, i.e. "require" is broken apart as "requ-ire". This is contrary to what I expect because of the rules of syllabication, which you'll find described at ​http://en.wikipedia.org/wiki/Syllabification. Now, those rules are somewhat complex and might be considered beyond the scope of a command-line argument parsing library. Thus, most code that needs to perform word-wrapping opts to use a simpler approximation, i.e. to break lines apart at *whitespace*. If you check out your source code, "options_description.cpp", you'll find that you have implemented an algorithm that does this, but unfortunately it appears that your code fails to take the length of the default argument into account. I say this because the algorithm works just fine when there's no default argument. When there is one, word-wrapping does not work fine.

If you need further clarification, please don't hesitate to ask.

[s.ochsenknecht@…]

patch

[s.ochsenknecht@…]

I just attached a patch which improves the word wrapping (small fix). I also added a test case for word wrapping.

Please comment.

[Peter Simons]

The patch applies cleanly to the current SVN HEAD, and it does fix the problem in my test program. Looks good to me. Thank you very much.

[Vladimir Prus]

(In [57517]) Fix wordwrapping in presense of default parameters.

Fixes #2613. Patch from Sascha Ochsenknecht.