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- Path: chronicle.mti.sgi.com!austern
- From: harinath@cs.umn.edu (Raja R Harinath)
- Newsgroups: comp.std.c++
- Subject: Re: possible extension -- typeof(expr)
- Date: 08 Mar 1996 16:06:31 PST
- Organization: Dept of Comp Sc, Univ of Minnesota
- Approved: austern@isolde.mti.sgi.com
- Message-ID: <d93f7jp4d6.fsf@hecto.cs.umn.edu>
- References: <199603061757.AA17403@zacatecas.optimum.com>
- <u9ag1t3njg.fsf@yorick.cygnus.com>
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- X-Original-Date: 08 Mar 1996 17:11:33 -0600
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- Originator: austern@isolde.mti.sgi.com
-
- In article <u9ag1t3njg.fsf@yorick.cygnus.com>
- jason@cygnus.com (Jason Merrill) writes:
- >
- > >>>>> Tim Boemker <tjb839@zacatecas.optimum.com> writes:
- >
- > > Many times in working with STL I've wished for a new operator to return
- > > the type of an expression, much the same way sizeof returns the size of
- > > an expression.
- >
- > > It would allow programs like the following, for example:
- >
- > > set<foo, less<foo> > s;
- > > for(typeof(s)::iterator i = s.begin(); i != s.end(); i++)
- > > // do something
- >
- > > I suppose this must have been considered by now. Has anything come of
- > > it?
- >
- > It has come up in the committee, but no-one has made a formal proposal, and
- > it's too late now.
-
- Instead of introducing a new keyword `typeof', what about allowing this
- usage:
-
- set <foo, less<foo> > s;
- for (typename s.iterator i = s.begin(); ... )
- ^^^^^^^^ ^^^
- | |
- (1) (2)
-
- 1. Extending `typename' to a non-template context to allow (2).
-
- 2. Accessing a member type/typedef using the `.' syntax (and against an
- object) instead of the `::' syntax against a typename.
-
- (1) above solves the parsing problem associated with allowing syntax (2)
- independently, and uses an existing keyword (and extends its meaning,
- without, IMO, overloading it).
-
- - Hari
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