Manifest constants: why enum instead of invariant?

[Bruno Medeiros]

Don wrote:
> Bruno Medeiros wrote:
>>
>> Around how many bytes are we talking about here, just to get a 
>> concrete idea, does anyone know? I'm not familiar with the windows 
>> headers nor their D bindings, although I recently checked some of the 
>> windows d headers and there were many manifest constants. But I still 
>> don't know if their size would amount to something that significant. 
>> If for example, you have a cmd line program that prints one page of 
>> it's syntax/usage, just that single string would occupy the same space 
>> as 400 manifest constants or more.
> 
> 
> void main() {}    --> 79kB exe.
> -------
> import win32.core;
> void main() {}   --> 108kB exe.
> 
> So it looks like it's less than 32K. Less than 40% of the size of the 
> phobos runtime and gc. And a good linker would remove it ALL.
> 

It is more than I expected, but I still don't find such size significant 
enough.

> 
> BTW, I was the one who requested the feature in the first place.
> It was important for template metaprogramming. When you do something 
> complicated, the obj files contain masses of compile-time constants. (I 
> was experiencing 5Mb obj files where only a single int was used at 
> runtime!) It takes ages to save such a large obj file.
> Since you cannot take the address of such constants, there's no reason 
> for them to be retained, and I requested that they be discarded from the 
> obj file.
> 

5Mb!? Well, that's certainly significant enough then. Still the feature 
is only valid because the compiler/linker doesn't discard them. 
Hopefully in the future that will change, and the compiler won't 
generate unnecessary symbols in the first place.

-- 
Bruno Medeiros - Software Developer, MSc. in CS/E graduate
http://www.prowiki.org/wiki4d/wiki.cgi?BrunoMedeiros#D