[Boost-users] [program_options] allow_guessing compatibility issue

Subject: [Boost-users] [program_options] allow_guessing compatibility issue
From: Filip Konvička (filip.konvicka_at_[hidden])
Date: 2010-02-21 07:24:30

Hi,

I've just upgraded to boost 1.42 from 1.40, and it seems that the new 
feature 'allow_guessing', a default setting, breaks my existing code. I 
have two options: "lang" and "lang-dir", the first obviously a prefix of 
the other, and when my program is run with "--lang=en_US --lang-dir=.", 
the first argument is interpreted as "lang-dir". Even though the 
documentation says somewhere that one argument should not be a prefix of 
another with 'allow_guessing' on, this is a breaking change and should 
be put in a big red box somewhere on the front page :-)

If the change is intended to be kept for the future, it would be wise to 
detect the problem by examining the options, rather than wait until 
another problem occurs (in my case, the runtime exception is 
'multiple_options' when the user uses both options, and - much worse! - 
the option gets misinterpreted without a warning if he only uses the 
shorter option).

Cheers,
Filip