From: christopher diggins <cdiggins@videotron.ca>
I've just written in a working prototype of a library for writing C++ programs which can be treated in C++ code like Unix filters, i.e. redirected to and from streams, and other programs.
For instance:
fstream f("c:\\tmp.txt"); stringstream s; HelloWorldProgram() > f > UpperCaseProgram() > s;
Is there any interest in this kind of library, for boost? I am using it for writing test and demonstration programs of libraries, but I think it has a lot of other uses.
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." You cite an example in your article of piping the output of one *nix command to another using the output redirection operator, ">". The correct operator is the pipe, "|". You seem to have codified that misunderstanding, since you've overloaded ">" and not "|" for Program. 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. (Speaking of "pipeline," that is the *nix term for a series of filters piped together. Hence, your PipeChain class would be better named "Pipeline," and its "ChainTo" member function would be better named "PipeTo.") 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. -- Rob Stewart stewart@sig.com Software Engineer http://www.sig.com Susquehanna International Group, LLP using std::disclaimer;