Inheritance of purity

Jonathan M Davis jmdavisProg at
Thu Feb 16 19:54:50 PST 2012

On Thursday, February 16, 2012 19:41:00 Walter Bright wrote:
> On 2/16/2012 7:23 PM, Jonathan M Davis wrote:
> > No. Absolutely not. I hate the fact that C++ does this with virtual. It
> > makes it so that you have to constantly look at the base classes to
> > figure out what's virtual and what isn't. It harms maintenance and code
> > understandability. And now you want to do that with @safe, pure, nothrow,
> > and const? Yuck.
> I do not see how it harms maintainability. It does not break any existing
> code. It makes it easier to convert a function hierarchy to nothrow, pure,
> etc.

It makes it harder to maintain the code using the derived classes, because you 
end up with a bunch of functions which aren't labeled with their attributes. 
You have to go and find all of the base classes and look at them to find which 
attributes are on their functions to know what the attributes of the functions 
of the derived classes actually are. It will make using all D classes harder.

You should be able to look at a function and know whether it's pure, @safe, 
nothrow, or const without having to dig through documentation and/or code 
elsewhere to figure it out.

Doing this would make the conversion to const easier but be harmful in the 
long run.

- Jonathan M Davis

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