h*********o
发帖数: 62 | 1 Java generic is totally different from C++ template under hood. Does C++
use also sharing and type erasure when dealling template? If not, do you
see any problem/benefit to do the template in a way that Java does? Or why
didn't java use C++ template to do its generics? |
g*****g
发帖数: 34805 | 2 I'd take it this way. C++'s template is more flexible and powerful,
but too complicated and easily get abused, and make C++ pretty difficult
to learn and read at times.
Java generics, achieve about 90% of C++ template's power in a much simpler
way. Whether the other 10% is important is debatable. But so far, I haven't
heard a claim something can't be implemented in Java due to
this insufficiency.
why
【在 h*********o 的大作中提到】
: Java generic is totally different from C++ template under hood. Does C++
: use also sharing and type erasure when dealling template? If not, do you
: see any problem/benefit to do the template in a way that Java does? Or why
: didn't java use C++ template to do its generics?
|
a*****k
发帖数: 704 | 3 I think Java wants to be back compatible with its old code
why
【在 h*********o 的大作中提到】
: Java generic is totally different from C++ template under hood. Does C++
: use also sharing and type erasure when dealling template? If not, do you
: see any problem/benefit to do the template in a way that Java does? Or why
: didn't java use C++ template to do its generics?
|
r*********r
发帖数: 3195 | 4 c++ uses type expansion. java uses type erasure. exactly opposite.
c++'s way may lead to code bloating.
but c++'s template uses integers as type parameters,
which makes the mechanism Turing complete. |
y*******g
发帖数: 6599 | 5
Can you explain in more detail? why integer as type parameters makes it
Turing complete
thanks
【在 r*********r 的大作中提到】
: c++ uses type expansion. java uses type erasure. exactly opposite.
: c++'s way may lead to code bloating.
: but c++'s template uses integers as type parameters,
: which makes the mechanism Turing complete.
|
r*********r
发帖数: 3195 | 6 因为所有的计算问题都可以归结为(reduce to)整数的加减乘除.
CPU 的核心是 ALU. ALU 能做的操作也就是整数的四则运算. |
r*********r
发帖数: 3195 | 7 think of c++'s template mechanism as a functional language,
like Haskell or ML.
it has integer and boolean operations, also control flows like
selection and repetition ( actually recursion), and assignment
(with typedef and static constant integer definition).
think about the following piece of code. (copyrighted by me. :)
the real computation is done by the compiler.
#include
template
struct int_
{
static const int value = n;
};
template
struct plus |
