Vladimir Prus wrote: Hi Volodya,
Do you provide the ability to use different separators for sequences, sets and maps?
In the review version of the library, there are two sets of default values: one for n-ary types formatting as "( a, b )" and one for the other sequence types, formatting as "[ a, b, c ]". In the version I am rewriting, I only have one set of default formatting: "[ a, b, c ]".
That's bad, I'd rather prefer different formatting styles for sets and vectors.
Hmm. Note that this is for the default values, i.e. you can set the formatting you want when constructing a format object construct.
Then I don't understand why you can set different default style for those kinds of object, and cannot selectively override the style
Because the way I am storing it on the stream is based on decoration type (open; close; separator) and not on the format object type.
Why? Is there any specific difficulty with using format object type (or "kind") as key?
The current implementation in the post-review version that I am developing uses a simplified approach in dealing with pword -- it assumes that the type is const CharT * and is not allocated (i.e. is a string literal). It would be possible to do based on format object type, but that would increase the complexity of the code.
A wrapper_decorator is one that only has open and close decoration values. Thus, it wraps the object associated with it (via a format object):
template< class OutStream, typename T > OutStream & write( OutStream & os, const T & elem ) { return( os << open << elem << close ); }
Is this a method of 'wrapper_decorators'?
It is a method of the format object used when writing to a stream.
I agree that you might want to store and then restore STL container from a file, and the library addresses this need to. But I don't understand why you would want to customize the formatting style. Basically, you either should the data to user, or not. In first case, you need a single usable style. For the second case, you might need another "compact" style. I don't see the point of customization.
It is currently possible to state what style formatting an object takes using the decorate function (format in the review implementation). Thus:
// review implementation: std::cout << io::formatob( vec ).format( "( ", " )" ); // ( a, b, c, d )
Here, the separator is not set and thus takes the default value (the one provided by one of the mechanisms outlined above).
Ok, aside from naming, the above is fine.
The naming issue has been discussed earlier in the review. In the post-review version, the above example is: std::cout << io::object( vec ).decorate( "( ", " )" ); // ( a, b, c, d ) (I know the review is still in process, but I have been working to address the issues in the review version of my library.)
You might want to customize formatting for various reasons. One example is if you have: std::list< std::string > names; and want to write that out as a HTML ordered list. You can do the following:
std::cout << io::formatob( names ).format( "<ol><li>", "</li></ol>", "</li><li>" );
Is this a practical use case?
Reviewers have requested the ability to generate XML/HTML. This is to show that it is possible to do that within the existing framework.
Well, you can print 'names' this way, but if you want to print 'Person', you'll need much more powerfull tools. Anyway, if the overhead is small, no problem.
If Person supports << on a stream, you can do: std::list< Person > people; std::cout << io::formatob( people ).format( "<ol><li>", "</li></ol>", "</li><li>" );
It is also possible to provide a basic form of message localization, reading a std::map< std::string, std::string > in from a file. E.g.: [snip] That's more like an artificial example, I think. For practical uses, the message catalog would have to contain comments, at least, and that again requires much more complex parser.
This is true. Although, you could write a custom state object to skip comments and then bind that to the formatter.
I'll try to write a complete review soon, so stay tuned ;-)
:) (What frequency are you broadcasting at ;)) Regards, Reece _________________________________________________________________ It's fast, it's easy and it's free. Get MSN Messenger today! http://www.msn.co.uk/messenger