Re: [boost] Any interest in a library for supporting program reuse?

From: Rob Stewart (stewart_at_[hidden])
Date: 2005-01-07 14:00:02

From: christopher diggins <cdiggins_at_[hidden]>
> From: "Rob Stewart" <stewart_at_[hidden]>
> 
> > From what I can see, you use the term "program" to mean an
> > instance of class Program or, more specifically, a derivate
> > thereof.  That isn't what I think of when I see the word
> > "program."
> 
> What would you suggest the name of the class be instead? It is intended to 
> provide the main entry point for a program, so that the program can be 
> easily reused separately.

>From what I see, you're packaging functions, not system() calls
to executables or separate processes connected by some IPC.

> > Finally, your Program class is too intrusive since one must
> > derive from it.  It would be better if there was a make_filter()
> > function template called with a function (object) returning a
> > streamable object.  Then, make_filter() can return an object
> > which can invoke the function(object) as necessary and can be
> > chained with other instances to create a pipeline.
> 
> Why is it considered better to model a concept rather than inherit from a 
> base class and override a virtual function? It seems to me that it is 
> simpler to explain to a newcomer to inherit from a class, and it is more 
> apparent from looking at the code what is actually happening.

If I already have a function (object) that provides the desired
output, why must I create a class, implement a member function
that forwards to that function(object), and then use the class?
A simple call to make_filter(f) will do the job without the need
to write any code.

> > Oh, I should also point you to Jonathan Turkanis' IOStreams
> > Library (recently accepted, but not yet added to Boost).  See
> > http://home.comcast.net/~jturkanis/iostreams/ for code and
> > documentation.  Look especially at the filters functionality.
> 
> I am sorry but I don't see the connection with the iostreams library and 
> what I am doing. Could you explain the similarities?

Perhaps if I understood the distinction you're trying to make
between a "program" and ordinary functions, we can understand one
another better.

-- 
Rob Stewart                           stewart_at_[hidden]
Software Engineer                     http://www.sig.com
Susquehanna International Group, LLP  using std::disclaimer;