I would rewrite it to something like this:
import std.stdio;
import std.functional;
template BTree(ValueT, KeyT = ValueT,alias KeyF = unaryFun!"cast(const)a")
{
class BTree
{
auto getKey(ValueT val) {
return KeyF(val);
}
}
}
void main()
{
auto btree1 = new BTree!(char)(); // Removing this line eliminates the
error.
auto btree2 = new BTree!(int)();
}
On Sun, May 27, 2018 at 9:03 AM, Vijay Nayar via Digitalmars-d <
[email protected]> wrote:
> On Saturday, 26 May 2018 at 11:56:30 UTC, Vijay Nayar wrote:
>
>> The error is:
>> ```
>> onlineapp.d(8): Error: function literal `__lambda6(char a)` is not
>> callable using argument types `(int)`
>> onlineapp.d(8): cannot pass argument `val` of type `int` to
>> parameter `char a`
>> onlineapp.d(15): Error: template instance `onlineapp.BTree!(int, int,
>> function (char a) => a)` error instantiating
>> ```
>>
>
> Just to clarify. In the example above, if I create a 'BTree!int' by
> itself, it's fine. If I create a 'BTree!char' by itself, it's fine also.
> But if I create both, even if they are created in different modules, the
> compiler seems to mix up the types of the function template-parameter, and
> tries to fit a 'char' to the 'int' function or an 'int' to the 'char'
> function, depending on which was declared first.
>
