Am 22.10.2011 05:48, schrieb Robert Jacques:
On Fri, 21 Oct 2011 17:23:17 -0400, Daniel Gibson
<[email protected]> wrote:
Am 21.10.2011 21:07, schrieb Vladimir Panteleev:
Hi,
Igor Stepanov has created a patch for DMD and Druntime which adds RTTI
information for class and struct members.
Example:
import std.stdio;
class Foo
{
static void PrintHello()
{
writeln("Hello");
}
}
void main()
{
auto info = cast(OffsetTypeInfo_StaticMethod)Foo.classinfo.m_offTi[0];
assert(info.name == "PrintHello");
auto print = cast(void function())info.pointer;
print(); //prints "Hello"
}
While the inclusion of such functionality into the language remains a
disputed matter, would anyone be interested in an unofficial patch for
this?
Walter: would it be okay if the compiler changes were published as a
GitHub fork, or should we stick to patches?
I'd love to see proper runtime reflection support in D, including
functionality to get information about available methods (their name and
parameters) and a way to call them.
What do you mean by their 'parameters'? What about overloads?
Attributes? Arguments? Argument attributes?
Primarily arguments. That should help identifying overloads.
But attributes and argument attributes are needed as well.
Something that is close to what Java offers would be great.
And what, exactly does JAVA offer? What works? What doesn't work? What's
missing?
See
http://download.oracle.com/javase/6/docs/api/java/lang/Class.html
You can access constructors (look for one by it's parameters or get all
of them), the same for methods (methods the class declares and all
methods, i.e. also inherited ones), implemented interfaces, fields, ...
BTW: I don't really see the problem with providing this information
(overhead-wise) - the information needs to be available once per
class/struct, but objects of classes just need one pointer to it (other
types don't even need that because they're not polymorphic and - like
methods of structs - the address of the information is known at
compile-time).
1) Unused information is simply bloat: it increases exe size, slows the
exe down and increases the runtime memory footprint.
Yeah, but (mostly) only per class, not per object (besides one pointer
per object, which shouldn't be that bad and something like this seems is
already there for the existing typeinfo)
2) On a lot of systems (i.e. consoles, embedded, smart phones, tablets)
memory and disk space are both highly constrained resources that you
don't want to waste.
3) RTTI provides a back-door into a code-base; one that for many reasons
you may want to keep closed.
Yeah, it may make sense to be able to deactivate it.
Cheers,
- Daniel
