D-etractions A real world programmers view on D

[Peter Alexander]

On Saturday, 25 August 2012 at 00:22:58 UTC, bearophile wrote:
> Pragma Tix:
>
>> IMO a voice, D core developers should listen to.
>
> Even assuming all the things he has said are true, what do you 
> suggest D core developers to do?
> Example: how can D language devevelopers help D programmers 
> better refactor D code? Maybe having some built-in refactoring 
> features?

The D language is designed in such a way that makes many 
automated refactoring tasks incredibly difficult, if not 
impossible.

An example from Walter's recent talk:

struct A {
     int a;
     mixin(bitfields!(
         uint, "x", 2,
         int, "y", 3,
         uint, "z", 2,
         bool, "flag", 1));
}
A obj;
obj.x = 2;
obj.z = obj.x;


A common (and simple) refactoring task included in most IDEs is 
to rename a variable. Imagine what's involved in renaming the x, 
y, and z from the bitfield in the above code. You would have to 
expand the template (which involved CTFE) and then somehow infer 
that the name of the variable came from that string in the 
template args.

Okay, so bitfields are rarely used, but many templates involve 
some use of CTFE, and templates are very common in D code. It's 
good that D's parser is fairly simple to implement (compared to 
C++ anyway), but to do automated refactoring you need simple 
semantic analysis, and this is something that D does not have.