redirecting cin

[Bo Thorsen]

On Tuesday 11 December 2001 17:11, Andrew Sutton wrote:
> hi all,
>
> quick question (that may be dumb - or inappropriate, but i didn't know
> where else to post to. so if i'm wrong, sorry in advance)
>
> i have a bunch of different parsers in a collection. the parsers are
> flex/accent (like bison but parses context free grammars). the parser code
> is entirely written in C so i'm encapsulating the actual frontend parser in
> a shared library to be dynamically loaded when the executable needs it.
> this does a pretty good job avoiding collisions between the parser code
> (e.g. yytext). since the entire application is written in C++, i'm writing
> interfaces in C++ so i can just call:
>
> MyParser parser;
> parser.parser( some_file_stream );

Hold it right there, mister. Wrong design here, the parser method should take 
a general inputstream instead of a filestream. No need for you to use one of 
the specializations when you can just work on general input.

Then add an overloaded method to make an ifstream from a filename and call 
that. And you will find that if you change the argument type to istream, it 
will accept cin.

Bo.

-- 

     Bo Thorsen                 |   Praestevejen 4
     Free software developer    |   5290 Marslev
     SuSE Labs                  |   Denmark