Compiler patch for runtime reflection

[Alex Rønne Petersen]

On 22-10-2011 05:48, Robert Jacques wrote:
> On Fri, 21 Oct 2011 17:23:17 -0400, Daniel Gibson
> <metalcaedes at gmail.com> 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?
>
>> 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?
>
>> 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.
> 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.

You could just introduce a -reflection switch to include reflection 
information.

- Alex