Fully dynamic d by opDotExp overloading

[Andrei Alexandrescu]

Nick Sabalausky wrote:
> "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:
> 
> 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.

I was expecting this objection. I think it's not based because unifying 
syntax is a major part of adding such a feature. If we get to dynamic 
invocation but we can't go the last mile, we failed. Look at 
IDispatch-based programming in C++ vs. interpreted languages.

>> 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.

Of course. One thing that suggests the righteousness is not necessarily 
on your side is that plenty knowledgeable, intelligent, credible people 
use and advocate dynamic typing. Asserting that they simply miss the 
point is a bit tenuous.

> 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. 

I'm with you, and in wake of my frequent postings I guess it's pretty 
known by now that nothing makes me more annoying than knowing 100% I'm 
right :o). Certainly I'm not one who "agrees to disagree" and I'm glad 
you aren't either.


Andrei