Java Gets Templates

lastberserker writes "Call them all you want - generics, parametrized types, thingamagic mumbojumbo - but (tada!) Java gets templates in 1.5 release. Nice landing after 5+ years of dancing around a bush. Competition is good, pardon my pun."

Comments

Operator Overloading?

[Wrexen]

Does this mean Java will get operators soon? Back when Java was introduced, lack of templates was called a "feature", just like the lack of operator overloading. Have the designers seen the light?

Re:Operator Overloading?

[metalpet]

c++ folks are used to use operator overloading with templates together. The sample code 3 posts above does just that.. the "ab" assumes the "" is overloaded for the chosen type.

Java ain't complete 'till C# compiles on it?

(if Java is gonna have weird cool features added, I'd like to vote for what I read in the Eiffel doc the other day: design by contract, with pre and post conditions and class invariants. )

Good, and when do we gets enumerated types?

[Pascal Sartoretti]

After years of discussions, Sun aknowledges that, although life is possible without generics, it is often better with them.

Now, how many years do we have to wait until they do the same with the good old enum type?

Pascal

AAAAAAAAArgh -- missing the point sooo badly

[Anonymous Brave Guy]

Sorry, but I'm going to rant now, because every time I see this ill-informed argument it really annoys me.

Operator overloading is a fact of life when you are working with generics. Suppose I want to write a generalised summation method, which adds up all the elements in a list, whether those are int, float, SomeComplexNumberType or whatever. Question: what well-known and easily understood notation would make sense to use when writing this method? Should I write another method called add that has several versions, for each type I'd like to add up? Or maybe it should be addTo? After all, by your own argument, verbose and descriptive names are the way forward. But what if someone else provides a fixed-point type with a method called sum instead? Or maybe a static method taking two fixed-point values called sumOf? Do you see my point here? If everyone uses + to mean +, then writing such code is easy. If everyone uses different notation, which is forced if you don't allow operator overloading, then what you get is unmaintainable crap that cannot take advantage of generics in many of the most useful ways.

Java already has operator overloading anyway. You have + to concatenate strings. You have a conversion operator called toString. You have / that divides real numbers, but takes the integer part of the result for integral types. The only difference between these and what you have in a language like C++ is that in Java, you can only take advantage of this concept where the Java designers want you to, whereas in C++, you can write your own types at full strength as well.

Yes, operator overloading can be abused. So can method naming (and no, you can't smack the developer on the head, if he happens to work on the other side of the world and you're stuck using his library). But op overloading is more than mere syntactic sugar, where generic programming is involved. There are accepted standards for how we write certain concepts such as addition or strict ordering, and operator overloading is necessary to allow user-defined types to meet those standards, and thus to allow well-written generic code to take advantage of parameterised types and such to best effect. Without it, you've got a fabulous canvas, yet nothing but coarse paintbrushes to draw with.

Alas, as is so often the case, I fear the Java community has been too quick to think it understands, and to go for the buzzword feature without investigating the supports deeply enough. Parameterised types are a good start, and I'm glad to see them included, but I suspect that with experience, there'll be some serious enhancements in a couple of revisions' time...

Bjarne was right! :)

[Bish.dk]

So it turns out that Bjarne was right in his interview with Visual C++ Developers Journal in June 2000:

Very little in Java is new to a student of programming languages, so there has been little effect on the C++ definition. In that area, Java is still playing catch-up (for example, I think it is just a matter of time before Sun will add a template-like mechanism to Java).

-- Henrik

Re:Too little, too late

[pmz]

This is also why Microsoft is so successful - they constantly innovate, rather than sitting on their market dominance.

Sure they do. Microsoft is extremely good at seeing what other people are doing and, then, copying, buying, or squashing it to meet their agenda. In the case of C#, they first inhibited Java with their VM "embrace and extend" scheme, and then took Java, copied it, renamed it, and added a few things.

I guess you could call standing on other peoples shoulders innovation, but that is a relatively weak use of the word. Microsoft is more like the business partner that is your friend right up to the point of stabbing you in the back and taking credit for your work.

As for real innovation, I often wonder what "killer apps" were stifled over the years by Microsoft. Like weeds in a garden, Microsoft is always there...