[boost] Re: Some comments on program_options/howto.html

From: Vladimir Prus (ghost_at_[hidden])
Date: 2004-11-02 11:00:26

Hi Peter,

> I dutifully followed the link from the --no-foo thread, and I have some
> comments.
> 
> The Winmain Command Line section says split_command_line in the text,
> split_winmain in the example code.

The text is wrong and example is right, the function is called
"split_winmain". I'll fix the typo right now.

> The Response Files section shows example code for parsing a response file
> using Tokenizer. Why shouldn't one be able to use split_command_line
> instead? There doesn't seem to be any difference between a command line in
> string format and a response file.

Good question. The problem is that split_winmain uses Windows-style quoting
rules, while tokenizer uses more Unix-like rules. I'm not sure which syntax
the response files should use.

> Also, response file support doesn't seem proper. Response files should
> work like this:
> 
> @file1 --option=value @file2
> 
> If file1 contains --option, it will be overriden by the command line.
> Similarly, all options in file2 will override both file1 and the command
> line --option=value. From a cursory look at the example, this doesn't seem
> to be the case, but I may be wrong. 

In the example, options on the command line will override options in both
response files. If that behaviour is not correct, I'll have to modify the
example by looking over vector of parsed options that's returned by
parse_command_line and expanding @ options. Do  you think that specifying
the same option in @file1 and @file2 is OK, and definition in @file2 should
override the previous one? On the command line, two duplicated assignments
to a scalar option results in an error.

> An additional parser could have been 
> used to enable this behavior if it were possible to return more than one
> option/value pair from it. (This would also allow "option bundles" like
> -O1 expanding into a set of option/values.)

I plan to make additional parser return vector<option>. But that's after
release.

- Volodya