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From: quarrie@cds001.cebaf.gov (David Quarrie)
Newsgroups: comp.lang.eiffel
Subject: Re: Three ways to use library-like classes
Keywords: library constants
Message-ID: <1991May1.132033.29479@murdoch.acc.Virginia.EDU>
Date: 1 May 91 13:20:33 GMT
References: <1991Apr30.140340.25415@bony1.bony.com>
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Reply-To: quarrie@cds001.cebaf.gov (David Quarrie)
Organization: CEBAF (Continuous Electron Beam Accelerator Facility)
Lines: 62

--

In article <1991Apr30.140340.25415@bony1.bony.com>,
richieb@bony1.bony.com (Richard Bielak) writes:
|>Path:
|>murdoch!uvaarpa!haven.umd.edu!udel!wuarchive!uunet!bony1!richieb
|>From: richieb@bony1.bony.com (Richard Bielak)
|>Newsgroups: comp.lang.eiffel
|>Subject: Three ways to use library-like classes
|>Keywords: library constants
|>Message-ID: <1991Apr30.140340.25415@bony1.bony.com>
|>Date: 30 Apr 91 14:03:40 GMT
|>Reply-To: richieb@bony1.UUCP (Richard Bielak)
|>Organization: Bank of New York
|>Lines: 57
|>
    [lines deleted]
|>
|>3) Expanded attribute (my way :-)
|>
|>        class COMPLEX is
|>        feature
|>                mlib: expanded SINGLE_MATH;
|>                [...]
|>        end; -- COMPLEX
|>
|>        Now I can can make calls "mlib.whatever" without having to do
|>        a Create on "mlib".
|>
|>
|>It works. What do you think?
|>
|>
|>...richie

The method I've used, at least in situations where I want to use a class
having lots of constant definitions, is something like the following

	class COMPLEX is
	feature
		mlib: SINGLE_MATH is
			once
				Result.Create
			end; -- mlib
	end; -- COMPLEX

This might look like overkill for the situation where the class contains
mainly constants, but it avoids exceeding the limit of 1000 features in an
Eiffel class (which amazingly enough I have managed to exceed when using
a class containing all the Motif constants), and by using a "once" routine, 
this attribute is shared by all objects of class COMPLEX, perhaps saving some 
space relative to Rithie's proposal. It also avoid having to explicitly 
"Create" the class. It does suffer some additional overhead though, especially
when fetching constants from the "included" class.

	David Quarrie
	CEBAF (Continuous Electron Beam Accelerator Facility)
	quarrie@cds001.cebaf.gov