Re: [boost] Boost.Application

Subject: Re: [boost] Boost.Application
From: Christof Donat (cd_at_[hidden])
Date: 2012-01-26 04:56:21

Hi,

>> When writing an application, how do I use boost::program_options to 
>> parse a
>> std::vector< std::string >? At least I have not found any overloaded
>> version
>> of parse_command_line(). Maybe I have just not seen it.
>>
>>
> The tutorial explains this. Also, see main_tutorial_3.cpp.

I see, thanks. I don't like it, though I don't have an alternative 
solution at hand. Somehow this feels very clumsy with that init() 
method. As example of a pure OO approach you could have a look at Qts 
QApplication. That one gets argc and argv as constructor parameters. Yet 
I do like the idea of using a vector< string > instead of the C like 
argc and argv construct.

Another approach would be to better integrate the Application and 
program_options. E.g. the Application could be initialized with an 
options object and a container object to hold the parsed options. Then 
the main() method (or, what I'd prefer the call operator) would simply 
get the already parsed parameters.

Of course there is also the option to extend program_options so that it 
can parse not only from argc and argv, but from a range of string like 
objects. Then you could use begin() and end() to create a range from the 
vector< string >, you could use argv[0] and argv[argc], or any other 
kind of range. That might also be usefull for situations where 
application is not used.

Personally I'd prefer the last option, because it opens up new 
possibilities for other situations as well and keeps application 
flexible as well. Integrating program_options in application would take 
away the liberty from the user to not use program_options for whatever 
reasons. The idea with init() is clumsy and passing argc and argv to the 
constructor is just like passing them to the main method itsself.

Christof

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