Finding out about D - 102

[Steve Teale]

OK, so structs are a different beast in D than they are in C++. This results in one of my most common pitfalls. I'll find myself writing:

struct A
{
   int a;
   int b;
}

A[] nameTooLong = ...;

foreach (whatever; thingie)
{
   nameTooLong[whatever.whatever].a = whatever.x*3;
   nameTooLong[whatever.whatever].b = whatever.y/3;

   // more of the same sort of stuff
}

So I get fed up typing 'nameTooLong[whatever.whatever]', and instead I write

foreach (whatever; thingie)
{
   A ntl = nameTooLong[whatever.whatever];
   ntl.a = whatever.x*3;
   ntl.b = whatever.y/3;

   // more of the same sort of stuff
}

Then I chase a bug in my program, which compiled OK. After some time, I realize that

   A ntl = nameTooLong[whatever.whatever];

is doing a copy, which is not what I was thinking about at all - old C++ habits.

ntl = ...;

has no effect whatsoever on nameTooLong[whatever.whatever].

So then - pissed off by that point - I rewrite it as:

foreach (whatever; thingie)
{
   A* ntl = &nameTooLong[whatever.whatever];
   // This suggests an ambiguity in the language?
   ntl.a = whatever.x*3;
   ntl.b = whatever.y/3;

   // more of the same sort of stuff
}

This works OK, but it's still not the D way to do things. Try:

foreach (whatever; thingie)
{
   alias nameTooLong[whatever.whatever] ntl;
   ntl.a = whatever.x*3;
   ntl.b = whatever.y/3;

   // more of yer same sort of stuff
}