RE: [boost] IO Formatting Manipulators

From: Reece Dunn (msclrhd_at_[hidden])
Date: 2003-06-03 13:31:43

Paul A. Bristow wrote:

>My impressions of this are highly favourable from the examples and tests, 
>but I
>haven't tried to use it in anger yet as I am uncertain if it compiles with
>MS.net 2003 (aka 7.1?).  Is this known yet? Suck it and see?

I do not have access yet to MS VC7.1, so I have not been able to test it on 
this compiler. I have only had the oppotunity to test on:
*  MS VC7.0
*  GCC 3.2.2
*  GCC 3.3
*  Borland C++Compiler 5.5

It should work on VC7.1 since it works on VC7.0 and GCC 3.x. If anyone can 
test my library on this compiler, or any others, I'd be greatful for 
feedback (test/example output, error messages, etc).

Type/outputter deduction is working for GCC 3.x. The type deduction works on 
Borland, but it chokes on outputter deduction (can't figure this one out 
yet). MS VC7.0 does not have this facility since there is no template 
partial specialization; not checked for VC7.1 (may or may not need 
modification to work on it).

I have used a configuration header to allow flexible management of 
facilities that do not work on various compilers.

>(A feature I do not see is control of the number of items before a newline. 
>I am
>not sure if this is a sensible feature in these days of scroll bars and I 
>can
>see it is fraught with difficulties).

The results embedded in the examples are manually formatted with newlines to 
make them readable. In order to implement this, you will need to override 
the outputter used by the program to count the number of items being 
outputted. You would need to work out what the base unit is (e.g. basic 
value, pair value) and use this as a starting point. Such is the use of 
custom outputters :-)

This would possibly be a good topic for the documentation - creating custom 
outputters.

NOTE: The above will not work with automatic outputter deduction.

>I didn't spot any examples with floating point values.  Do these introduce 
>any
>hidden snags?

Not so far as I am aware:

std::list< float > lflt;
lflt.push_back( 1.1 );
lflt.push_back( 2.1 );
lflt.push_back( 3.1 );

std::cout << boost::io::formatlist( lflt ) << '\n';

Regards,
Reece

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