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From: tynor@hydra.gatech.edu (Steve Tynor)
Newsgroups: comp.lang.eiffel,comp.lang.objective-c
Subject: Re: Whose debugger is better, Eiffel or Objective C?
Message-ID: <TYNOR.91Mar4100827@hydra.gatech.edu>
Date: 4 Mar 91 15:08:27 GMT
References: <1991Feb26.045704.11186@ecst.csuchico.edu>
	<1991Feb26.155726.9531@noose.ecn.purdue.edu> <6501@stpstn.UUCP>
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In-reply-to: cox@stpstn.UUCP's message of 3 Mar 91 13:37:38 GMT

In article <6501@stpstn.UUCP> cox@stpstn.UUCP (Brad Cox) writes:
| In article <1991Feb26.155726.9531@noose.ecn.purdue.edu> giacomet@haley.ecn.purdue.edu (Frederic Giacometti) writes:
| >all my debuging is done with assertion monitoring. Sometimes, I've
| >used the trace capability but that's it. I'd believe the assertion
| >by Eiffel's authors that traditional debuggers are somehow obsolete
| >in Eiffel to be relevant, if not true. I must also say that, unlike 
| >my experience with Objective-C or C, the debugging stage with Eiffel
| >has been much limited.
| 
| Why not use C or Objective-C's assertion monitoring? Simply
| #include "assert.h" and have at it.
| {
| 	assert(precondition);
| 	...body...
| 	assert(postcondition);
| }
| Class invarients are, IMO, best expressed in a separate file, distinct
| from the class under test. I call these separate files "gauges" by 
| analogy with inspection gauges of tangible domains like manufacturing.

I disagree - class invariants are an integral specification of the
class's behavior - they ought to be in the same place as the class
specification (the class source file in Eiffel, the class header file in
C++, I'll have to plead ignorance about ObjC).  As much as I like
<assert.h> in C and it's derivatives, it's not as good as the Eiffel
assertion mechanism. The pre- and post-conditions of a routine and the
class invariant are visible for all to see - not buried in the
implementation.  Of course, it's possible to have inline assertions
(equivalent to the assert() macro) in Eiffel too (the `check'
instruction).

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Eiffel: Accept no substitutes
                     
    Steve Tynor
    Georgia Tech Research Institute
    tynor@prism.gatech.edu