Re: [boost] Re: Re: Re: Re: Functions as Filters (was Program Reuse...)

From: christopher diggins (cdiggins_at_[hidden])
Date: 2005-01-11 14:23:02

----- Original Message ----- 
From: "Rob Stewart" <stewart_at_[hidden]>
To: <boost_at_[hidden]>
Cc: <boost_at_[hidden]>
Sent: Tuesday, January 11, 2005 1:18 PM
Subject: Re: [boost] Re: Re: Re: Re: Functions as Filters (was Program 
Reuse...)

> From: christopher diggins <cdiggins_at_[hidden]>
>> From: "Jonathan Turkanis" <technews_at_[hidden]>
>>
>> >> void DoWork() {
>> >>   // do work
>> >> }
>> >>
>> >> int main() {
>> >>   DoWork();
>> >> }
>> >
>> > Okay, but do you really expect people to start writing programs this 
>> > way?
>>
>> Yes, especially if the iostreams library provides the functionality to 
>> them.
>> My point is that C++ code is pointlessly hard to reuse as is, and I am
>> pushing for new ways to make small programs more reusable. This is 
>> incrediby
>> important when managing large numbers of small programs (for instance
>> library tests and demos). It is trivial to refactor code to make it look
>> like the above, just cut and paste the main!
>
> You assume that nothing fails in the above, since main() falls
> through and, therefore, returns zero.  Are you proposing that
> main() should actually catch exceptions and, possibly, extract
> its exit status from the exception object?

No I am not proposing that. I don't care at this point how a programmer 
chooses to deal with that.

>> > I
>> > think people would only do this to conform to your filter concept. My
>> > question
>> > is: why aren't the other concepts sufficient?
>>
>> The other concepts are fine, they are just more obfuscated than most
>> programmers require. Just imagine trying to explain how to use a filter
>
> You've admitted to being relatively new to C++.  Can you rightly
> determine what "most programmers require?"

First off, I said "I'm not exactly wet behind the ears". Exactly how much, 
or how little I know about C++ should be irrelevant. I think it is extremely 
rude to put someone's credentials into question in such a discussion. If you 
disagree with something I said, then please state why, don't question the 
validity of my opinion.

>> concept in a way which makes sense to a Java / Delphi / C programmer. I
>> think it is important to try and provide alternatives where possible 
>> which
>> makes sense to professional programmers who may not be familiar with the
>> intricacies of generic programming techniques and functors.
>
> A reasonable goal, though all C++ programmers need to become
> familiar with generic programming and function objects.  These
> really aren't novel or academic techniques.

No, but they are overkill in cases when a void procedure will do just as 
well.

>> Nonetheless, I do currently have a non-trivial program which converts C++
>> into a <pre></pre> html tag, CppToHtmlPreTag, it operates obviously on 
>> the
>> stdin and outputs to stdout. It looks essentially like this:
>>
>> void CppToHtmlPreTag() {
>>   // calls multiple other functions to do the work
>> };
>>
>> int main() {
>>   CppToHtmlPreTag();
>>   return 0;
>> }
>
> So the result of this program is to write "<PRE>" to stdout, copy
> stdin to stdout, and write "</PRE>"?  Why do you need a program
> for that?

Sorry I was unclear, the CppToHtmlPreTag adds <div class="xxx"></div> tags 
around the various syntactic elements so that a css document can control 
coloring.

[big snip]
> This would be even easier to assemble via scripting and you don't
> need to compile anything or maintain source and binaries
> independently.

I am perfectly aware of how to use the various shells and scripting 
languages. I don't see how that is relevant to a discussion of C++ 
techniques.

CD