Re: [Opencxx-users] Re: Environment::Lookup Question/Problem

[Grzegorz J. <ja...@ac...>]

Scott D. Fleming wrote:
> 
> Hi Grzegorz,
> Thank you very much for your prompt response. Your advice was very 
> helpful; as you said, I was looking in the wrong environment. 
> Unfortunately, my problem has not been completely solved. If the 
> function that I want to lookup is overloaded, then Environment::Lookup 
> will always report the same version regardless of the arguments to the 
> call. I suppose this is because Environment::Lookup simply returns the 
> first symbol it finds with a name matching that of the function.
> 
> For example, if I have a class with an overloaded member function, like 
> this:
[...]
> 
> The obvious solution that I see here is to lookup all the possible 
> versions of the member function using Class::LookupMember, lookup the 
> types of the arguments using Environment::Lookup, and use the gathered 
> information to determine which version of the member function was 
> called.  Unfortunately, this solution is rather complex as there are a 
> lot of special cases to worry about (e.g., automatic type conversion in 
> C++, arguments that are expressions, etc.).
> 
> Again, any advice you offer towards a better solution would be most 
> appreciated.

I am afraid I don't see any easier solution. OpenC++ is missing the 
functionality you describe. Would like to implement this piece? (Perhaps 
not with all corner cases at first, e.g. omitting conversions simplifies 
a lot.)

BR
Grzegorz

> Thanks, Scott
> 
> 
> Grzegorz Jakacki wrote:
> 
>>
>> Hi,
>>
>> sdflemin wrote:
>>
>>>
>>> Hi,
>>> I have been using OpenC++ for about a year now, and recently ran into 
>>> a problem. I am doing member call translations (using 
>>> MemberCallTranslate), and I need to know if the member function that 
>>> the call is being made on returns void. I find that when the call is 
>>> made outside the member's class, the Environment does not contain the 
>>> member function's symbol. A stripped-down sample that illustrates the 
>>> problem follows.
>>
>>
>>
>> I don't have much time to look into it now, but it seems to me that 
>> you are looking in wrong environment. Given
>>
>>     C x;
>>     x->f();
>>
>> you should be looking for 'f()' in environment of class C, not in the 
>> environment of the call site.
>>
>> Given the fact that you are in a metaclass of C, you should be able to 
>> get hold on the right environment by calling 'this->GetEnvironment()'.
>>
>> Let me know if this does not work, I will have a deeper look.
>>
>>> I have used the Environment::Dump function before the Lookup to help 
>>> debug this, and sure enough, none of the Foo member functions appear 
>>> in the dump. The Foo class does, however...
>>
>>
>>
>> Seems right.
>>
>>> My question to you: is this behavior a feature that I don't 
>>> understand or a bug?
>>>
>>> If it's a feature, can you suggest a way for me to determine the 
>>> return type of foo_do_it() in the TranslateMemberCall() function?
>>>
>>> If it's a bug, can you suggest a patch? I am happy to patch the 
>>> OpenC++ source myself, but it will take me awhile to understand it. 
>>
>>
>>
>> It seems that no patch is needed here, but if you would consider 
>> contributing your work to OpenC++ there are always bigger and smaller 
>> jobs to do in OpenC++, OpenC++Core or OpenC++ website, just contact me 
>> for arrangements.
>>
>>> Any pointers you can give me would be great, and also, is there a 
>>> document that describes the OpenC++ source design?
>>
>>
>>
>> See opencxx/doc/architecture.html in CVS.
>>
>> BR
>> Grzegorz
>>
>>
>>
>>> Many Thanks, Scott
>>>
>>> PS: My thanks to the OpenC++ maintainers. It has been an extremely 
>>> useful tool for me, and I am glad that the project is alive and well.
>>>
>>>
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>>
>>
>>
> 
> 
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