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From: ngo@ymer.harvard.EDU (Thomas Ngo)
Newsgroups: comp.lang.c++
Subject: Re: [SUMMARY] Three ways to declare a function "const" in C++ 2.0
Message-ID: <4454@husc6.harvard.edu>
Date: 17 Oct 90 17:09:30 GMT
References: <NGO.90Oct16102625@tammy.harvard.edu> <SCP.90Oct17100405@grizzly.acl.lanl.gov>
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Reply-To: ngo@tammy.harvard.EDU (Thomas Ngo)
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Organization: Chemistry Department, Harvard University
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In article <SCP.90Oct17100405@grizzly.acl.lanl.gov>,
scp@acl.lanl.gov (Stephen C. Pope) replied to my original posting:

scp> ngo@tammy.harvard.edu (Tom Ngo) said:
scp> ngo> 
scp> ngo> In g++, you can declare a function "const", e.g.
scp> ngo>       const double sin( double x )
scp> ngo> [indicating that successive calls to this sin() need not be
scp> ngo> repeated if x has not changed in the interim...]
scp> ngo> 
scp> ngo> [In AT&T C++ 2.0, the "const" means the function returns a
scp> ngo> "const double", which is meaningless in this particular context...]
scp> ngo>
scp> ngo> Tony Hansen remarked:
scp> ngo>     It's a relatively new extension of g++.
scp>
scp> Only thing is, g++ doesn't always do anything with it; this is especially
scp> true of virtual methods. Word is that this g++ extension is going away...!

Interesting.  In support of making this extension go away, someone
else pointed out to me that in a case like

    const double* foo()

the const would NOT be meaningless in AT&T C++ 2.0.

  Tom Ngo
  ngo@harvard.harvard.edu
  617/495-1768 lab number, leave message