Thread overview
UFCS overrides alias this
Apr 12, 2015
Freddy
Apr 12, 2015
anonymous
Apr 12, 2015
Freddy
Apr 12, 2015
anonymous
April 12, 2015
----test.d
struct A{
	string b;
	alias b this;
}

struct MyRange{
	
}
char front(MyRange);
void popFront(ref MyRange);
bool empty(MyRange);

void test(A a){
	a.empty;
}
----
$ dmd -o- test
test.d(14): Error: function test.empty (MyRange) is not callable using argument types (A)
----
Is this intended behavior?
April 12, 2015
On Sunday, 12 April 2015 at 20:19:02 UTC, Freddy wrote:
>
> ----test.d
> struct A{
> 	string b;
> 	alias b this;
> }
>
> struct MyRange{
> 	
> }
> char front(MyRange);
> void popFront(ref MyRange);
> bool empty(MyRange);
>
> void test(A a){
> 	a.empty;
> }
> ----
> $ dmd -o- test
> test.d(14): Error: function test.empty (MyRange) is not callable using argument types (A)
> ----
> Is this intended behavior?

string's empty is actually a function in std.array or std.range or something, called via UFCS. You don't import std's empty, so the call can't match even when the alias this is tried.

Add the following, which brings std's empty into the overload set, and it works:

static import std.range;
alias empty = std.range.empty;
April 12, 2015
On Sunday, 12 April 2015 at 20:35:06 UTC, anonymous wrote:
> string's empty is actually a function in std.array or std.range or something, called via UFCS. You don't import std's empty, so the call can't match even when the alias this is tried.
>
> Add the following, which brings std's empty into the overload set, and it works:
>
> static import std.range;
> alias empty = std.range.empty;
----test.d
static import std.range;
alias empty=std.range.empty;
struct A{
	string b;
	alias b this;
}

struct MyRange{
	
}
char front(MyRange);
void popFront(ref MyRange);
bool empty(MyRange);

void test(A a){
	a.empty;
}
----
$ dmd -o- test
test.d(16): Error: overload alias 'empty' is not a variable
----
No idea what dmd is doing.

However it works with
----
private auto empty(string s){
	static import std.range;
	return std.range.empty(s);
}
----
April 12, 2015
On Sunday, 12 April 2015 at 20:48:57 UTC, Freddy wrote:
> ----test.d
> static import std.range;
> alias empty=std.range.empty;
> struct A{
> 	string b;
> 	alias b this;
> }
>
> struct MyRange{
> 	
> }
> char front(MyRange);
> void popFront(ref MyRange);
> bool empty(MyRange);
>
> void test(A a){
> 	a.empty;
> }
> ----
> $ dmd -o- test
> test.d(16): Error: overload alias 'empty' is not a variable
> ----
> No idea what dmd is doing.

Looks like order matters.

This works:

bool empty(MyRange);
alias empty = std.range.empty;

This doesn't:

alias empty = std.range.empty;
bool empty(MyRange);

I don't know if there's a reason for that or if dmd is just being silly.