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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."
Sounds like you don't get the point. The reason templates are useful is because it reduces the amount of code you need to write for common situations in a typesafe way. This makes your code more compact (duplicate code) and less error-prone (it's all type safe and you only write it once).
a d=6009 (lets hope /. gets this right). Lets hope all these goodies end up in 1.5.
BTW. generics are old news. The prototype compiler and the proposal have been available for at least a year. On the javalobby there's a link to some additional language extensions: http://www.javalobby.org/thread.jsp?forum=61&thre
Jilles
Doing mainly C++ development I've learned to love the STL and most recently the Boost libraries and I've long regretted that Java didn't support templates. It always confused me that with as much emphasis was placed on strong typing in Java that there was so much need for casting.
Although I'm glad to see the introduction of templates, I'm also concerned about how some of the problems I've encountered with C++ templates will be avoided. The biggest problem I've encountered has been the lack of interface checking.
For example the templated function for_each(begin, end, function) iterates from 'begin' to 'end' calling 'function' on each item inbetween. However there is no mechanism to specify that the type of passed to 'begin' and 'end' must have an equality operator and an operator* and 'function' must take one parameter of the type returned by *begin. This can cause very strange compiler errors when a user tries to pass a variable that doesn't support the proper operations to be compatible with the function. These errors actually appear to occur within the templated code, not the user-written code and can make determining the cause of these errors very difficult.
The Boost Concept Check library provides a way for programmers writing templated C++ code to enforce the interface requirements on the templated parameters in a way that gives more informative error messages. However this is rarely used, even in the Boost libraries. The documentation on the Boost Concept Check gives a good example of the kind of errors that C++ programmers dread.
In order for Java templates to be successful they will need to provide some manner of enforcing requirements on the interface necessary for the templated code to work and provide useful errors at compile time if it doesn't.