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

[dewar@merv.cs.nyu.edu (Robert Dewar)]

Wes says

<<Hear, hear!  Why would an Eiffel programmer want to simulate Ada, when
he/she could actually use Ada?  (And vice versa, lest anyone think
I'm making another language-bigot comment...)>>


Very often in such discussions, you see claims that

"feature x in language y can easily be simulated in language w using approach z"

The trouble with such statements is that they are almost always true, and
there almost always exists w,z for all x,y, but the observation is 
meaningless.

For instance, a C programmer by very restricted, very stylized use of
headers, together with amazing tools that enforce and monitor these
restrictions, essentially complete duplicate the effect of the separation
of Ada specs and bodies.

But the issue is not whether C programmers *could* do this, but whether
they *do* do this in practice? And certainly for that example, the answer
is (rather universally) no.

SO the issue with Eiffel is not whether you *could* get the effects, e.g.
ease of ability to separate spec and body in a CM environment, but whether
people *in practice* work this way.

Note how significant it is that I make a simple request for anyone to 
report in on how Eiffel would work together with a typical CM tool
like Continuus or Clearcase to achieve this kind of separation.

The only responses have been theoretical, pointing out that in very general
terms, with some unspecified additional tools, it could be achieved. But
even these theoretical reponses have not shown any awareness of these
CM tools -- one would almost begin to get the feeling that typical Eiffel
projects are not using CM tools at all, though that cannot be right (probably,
as is the case for Ada, most of the people working on real live projects
have better things to do with their time than read, let alone contribute to,
this rather wandering thread.

Still it would be nice to have at least ONE concrete experience report
that shows that the engineering details of this approach are practical.