John, On Wednesday 09 March 2005 11:11, Randall R Schulz wrote:

John,

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I'm particularly interested in generics. For example, it seems to me, that you should can build up concepts as interfaces and specify template classes with templates that must implement particular interfaces. This would be better than C++ because I don't think you can specify that a template class must, for example, implement assignable and equality comparable, in C++. (I know Boost does this, but there is some runtime overhead.) The new java may be capable of it if you're willing to accept .equals() instead of operator=(), etc.

I'm sure it's debatable, but I think Java generics are a poor substitute for proper templates.

As to your point about constraints on acceptable parameter types being missing from C++, that's not really true. If the template uses a member function, then any attempt to use as a parameter a type that does not provide it will cause template instantiation to fail.

By the way, there's already considerable commentary on the Web comparing C++ Templates and Java Generics. A Google search for "C++ Templates Java Generics" produces quite a few relevant hits.

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Randall Schulz

On Thursday 10 March 2005 2:30 pm, John Lamb wrote:

Davi de Castro Reis wrote:

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Yes. Boost has the concept_check stuff, but AFAIK, there is no runtime overhead at all. Also, you can guarantee the interface mixing templates and inheritance.

template <class T : public myInterfaceClassName> class ...

Pretty simple uh? But you rarely see people using it, because generic  programming and traditional object programming seems to be some sort of competitors.

I couldn't find any reference to this in the draft standard or in Stroustrup and I couldn't get an example like this to compile in g++ 3.4.2 or 3.4.4 (though I know 3.4.2 won't accept some legal stuff like class : public class A { ... } object;) John, We are talking Java 1.5 where generics are introduced, not C++. -- Jerry Feldman Boston Linux and Unix user group http://www.blu.org PGP key id:C5061EA9 PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9

Jerry Feldman wrote:

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On Thursday 10 March 2005 2:30 pm, John Lamb wrote:

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Davi de Castro Reis wrote:

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Yes. Boost has the concept_check stuff, but AFAIK, there is no runtime overhead at all. Also, you can guarantee the interface mixing templates and inheritance.

template <class T : public myInterfaceClassName> class ...

John, We are talking Java 1.5 where generics are introduced, not C++.

Hvit? Now I am confused. AFAIK, there is no 'template' keyword in Java and it would use 'extends' or 'implements' in place of ':' if it allows such things.

It's a nice idea though.. I like the idea that something important can be expressed through the syntax rather than just constructed through an idiom. This is true, but we were talking about Java Generics, which is effectively

On Friday 11 March 2005 2:36 pm, John Lamb wrote: the Java version of the C++ Templates. Time for someone to invent a new language :-) -- Jerry Feldman Boston Linux and Unix user group http://www.blu.org PGP key id:C5061EA9 PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9

On Friday 11 March 2005 3:35 pm, Randall R Schulz wrote:

Yes and no. We don't need another language in the spirit of Simula / C++ / Java. Perhaps something the integrates AOP with OOP would be a logical next step. There's got to be someone out there who does not like curly braces. Maybe someone will resurect COBOL :-) -- Jerry Feldman Boston Linux and Unix user group http://www.blu.org PGP key id:C5061EA9 PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9

On Fri, 2005-03-11 at 13:18, Jerry Feldman wrote:

On Friday 11 March 2005 3:35 pm, Randall R Schulz wrote:

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Yes and no. We don't need another language in the spirit of Simula / C++ / Java. Perhaps something the integrates AOP with OOP would be a logical next step. There's got to be someone out there who does not like curly braces. Maybe someone will resurect COBOL :-)

Its called KOBOL by the Kompany. There is a lot of old code out there. -- ___ _ _ _ ____ _ _ _ | | | | [__ | | | |___ |_|_| ___] | \/