Re: Interface/Implementation (was Re: Design by Contract)

[doylep@ecf.toronto.edu (Patrick Doyle)]

In article <dewar.873630067@merv>, Robert Dewar <dewar@merv.cs.nyu.edu> wrote:
>
>Though this technical point is completely irrelevant to the main thread
>of discussoin here, if you are saying that you should be able to use entities
>before they are declared. I strongly disagree. Sure my compiler can make
>multiple passes through a source document, but as a human reading the
>document, I prefer not to. There is a reason why we arrange text books,
>and other materials not to have forward references (such as mentioning
>a character in a novel before introducing them). Programs benefit in the
>same way from a basically linear approach, in which overall understanding
>can be obtaineed in a single linear pass.

Novels and program code are read in fundamentally different ways.  Program
code is a reference text, more like a dictionary than a novel.  If you
look up a word in a dictionary and it uses another word you don't know,
do you care whether this new word is before the first word?  Of course
not.

IMO, the idea that code is read linearly is a misconception.  Perhaps
the spec might be read linearly if a programmer is new to that package
and wants to immerse himself in it and learn it all at once.  This
usage is analogous to the usage of a text book, and perhaps dependency
ordering provides some nominal assistance here.  Other
than this particular usage, it's my experience that code is not read
linearly, so dependency ordering is addressing a non-issue, especially
in the package body.

 -PD

-- 
--
Patrick Doyle
doylep@ecf.utoronto.ca