Fully dynamic d by opDotExp overloading

[davidl]

在 Sat, 18 Apr 2009 03:45:43 +0800，Nick Sabalausky <a at a.a> 写道:

> "Andrei Alexandrescu" <SeeWebsiteForEmail at erdani.org> wrote in message
> news:gsak2p$1s8a$1 at digitalmars.com...
>>
>> I think there's merit in binding via strings. It makes for very flexible
>> code that is future-proof, dynamic-linking-friendly, and hot-swappable
>> without recompiling (e.g. you don't need to recompile because you now
>> implement an interface etc.) Reflection is very useful as well.
>>
>> I think D can and should allow string lookup for its methods. It's a
>> low-complexity proposition that adds a very interesting tool to D's
>> arsenal.
>>
>
> That's a separate issue. I absolutely agree with the usefulness of being
> able to invoke static methods via a string identifier at runtime. But I
> think opDotExp is an extremely flawed way to do it. A much better way  
> would
> be through a reflection mechanism:
>

The opDot func can be extremely restrictive by looking up a former added  
table which are function fingerprints registered by a method call like  
dynamo.addMethod("myfunc", &myfunc);
dynamo.Lenght or dynamo.mymethud would just result runtime exception,  
because you didn't register these functions.

> class Foo
> {
>     void bar() {}
> }
>
> auto foo = new Foo();
> traits(foo).func("bar").invoke();
>
> That way, you can have the benefits of  
> runtime-string-identifier-invocation
> (and have it on *every* class/method), but without completely loosing
> compile-time checking on the members of every class which is capable of
> using it.
>
>> If anything, this agreed-fest shows that the rift between static typing
>> and dynamic typing is alive and well. I've seen many discussions in  
>> which
>> people were mystified how anyone gets anything done in a  
>> statically-typed
>> OO language.
>
> ...Doesn't necessarily mean both sides have valid points. Just that  
> there's
> disagreement. Outside of diplomacy, it doesn't make any sense to agree  
> with
> something you disagree with, or disagree with something you agree with,  
> just
> for the sake a closing a rift. Better to just continue debating the  
> issues
> with logical arguments. If nothing gets accomplished, well ok, fine, but  
> so
> what? That's a lot better than coming to hasty-but-wrong agreement just  
> for
> the sake of agreement.
>
> I guess what I'm saying is, people coming to an agreement is all fine and
> dandy, but the most important thing is to arrive at the *correct*  
> agreement.
> If one group of people insist that "2+2=0" and another group insists that
> "2+2=10", then it's far better to keep analyzing and debating until  
> "2+2=4"
> is discovered and proven than to say "let's all be happy!" and hastily  
> agree
> that "2+2=5". Again, outside of diplomacy, people disagreeing is not the
> real problem, the real problem is that the best answer either hasn't been
> found or hasn't been unquestionably shown to be best.
>
>



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