Re: [boost] Iterator Adaptor Poll

From: Beman Dawes (bdawes_at_[hidden])
Date: 2002-07-26 06:16:18

At 04:46 PM 7/25/2002, David Abrahams wrote:

 >However, enough people have had problems approaching this library that I
 >thought it would be useful to ask about what would make a gentle
 >introductory example. Beman recently sent me the enclosed, but it seems 
to
 >define such an oddball toy iterator that I'm not sure it would be a very
 >good motivating example.

ia_experiment.cpp is definitely oddball and definitely a toy. It was 
written to help me understand why I was getting compile errors from a real 
adaptor.

Someone else can probably come up with an introductory example which is 
less oddball.

But I'd like to defend the general principle of "toy" introductory 
examples.

When someone knows nothing about a topic, a toy example is the best 
introduction. It is "known good", and can be used to verify that 
compilations using the library work as expected.  It can be modified to see 
the effect of changes. Because it is a toy, it is totally 
non-threatening.  It makes the reader feel superior, rather than like a 
dunce.

The "C Programming Language" and "C++ Programming Language" books both 
started with a little "hello, world" program, very much a toy. Although 
simple, it starts the ball rolling with something that works and is 
understandable almost every reader.

In the case of ia_experiment.cpp, it illustrates the relationship between 
the finished iterator, the Base class, and the Policies class with greater 
clarity IMO than documentation in any form other than C++ code.

--Beman