Re: Why can't I assign a mixin to an alias?

[Mihail-K via Digitalmars-d-learn]

On Friday, 10 June 2016 at 22:38:29 UTC, Dechcaudron wrote:

I have the following code:

private string getVariableSignalWrappersName(VarType)()
{
return VarType.stringof ~ "SignalWrappers";
}

void addVariableListener(VarType)(int variableIndex, void 
delegate(int, VarType))

{
	alias typeSignalWrappers = 
mixin(getVariableSignalWrappersName!VarType);

}

On compilation, the following error is issued:
Error: basic type expected, not mixin

Why should it be like that? I believe the compiler should not 
impose restrictions on what mixins can or cannot do :/


I'm no expert, but this looks like a grammar issue more than 
anything else. You can work around it by moving the alias 
declaration into the mixin.


mixin("alias typeSignalWrappers = " ~ 
getVariableSignalWrappersName!VarType ~ ";");

Re: Is it possible to use a template to choose between foreach and foreach_reverse?

[Mihail K via Digitalmars-d-learn]

On Saturday, 4 June 2016 at 14:32:23 UTC, pineapple wrote:

It would be fantastic if I could write this -

static if(forward){
foreach(item; items) dostuff();
}else{
foreach_reverse(item; items) dostuff();
}

as something like this -

foreach!forward(item; items) dostuff();

Is there any way to accomplish this?


As far as I recall, foreach_reverse is deprecated in favour of 
range operations.

ie.

  import std.algorithm, std.range;

  static if(forward)
  {
  items.each!(item => doStuff());
  }
  else
  {
  items.retro.each!(item => doStuff());
  }

As for your question, I suggest writing a range function that 
calls retro conditionally. Something like,


  items.direction!(forward).each!(item => doStuff());