Subj : Re: OO compilers and efficiency
To   : comp.programming
From : Flavius Vespasianus
Date : Thu Jul 21 2005 02:22 am

"Rob Thorpe" <robert.thorpe@antenova.com> wrote in
news:1121849306.769176.300410@g43g2000cwa.googlegroups.com: 

> Flavius Vespasianus wrote:
> Calling a virtual function may be though.  For example, the code
> must:- <add the offset of the function in question to the base vtable
> pointer> <from that address load the function pointer>
> <save caller saved registers on the stack>
> <construct call frame for the passed args, possibly not needed>
> <call the function>
> <make a stack frame>
> <return from the function>
> <restore caller saved registers>

Calculating the address of the virtual function can usually be done 
through indexed mode addressing. The stack frame setup is the same no 
matter what language you use. Using temporaries can cause problems. Use 
const references to get around most of them.

>> The alternative, in the absence of OO is a large case statement;
>> hardly efficient either.
> 
> What the OP is talking about is using getter and setter functions
> rather than global variables.  So, in this case a load from memory
> could be used instead.

If it can be done in one or two instructions, there's no reason the C++ 
can't inline it into the same number of instructions.

> Interesting, personally I think C is a beautiful programming language.
> There are many better languages today, the problem is that they are
> not so well known.

For elegance in systems software, you should see BLISS. Too bad AT&T was 
giving C away for free while Digital was charging $40,000 (10 times what 
it charged for C) for Bliss. Bliss had an unbelieveable macro language 
that you could build all kinds of tables with. Bliss also allowed you to 
lay out structures down to the bit level, something great for systems 
work.

It's unfortunate that language usage has been driven by hype and 
marketing factors rather than actual usability. I find it amazing that 
there are people out there who actually think that C# or Java are 
improvements over C++.....or that the Java byte code was an original 
idea.

We should be using something today that:

1. Has pascal syntax simplicity and safety
2. Ada threading and templates (tasks and generics)
3. C++ OO capabilities
4. Bliss macros !!!!!

I do a lot of code conversion from C++ to Object Pascal and every time I 
find many programming errors in my C++ code because of Pascal's much 
better error checking.

For my main project, it takes several minutes to compile the C++ version. 
The equivalent Object Pascal code compiles in less than a second.

.