Re: Default Template Instantiation

[Heromyth via Digitalmars-d]

On Monday, 19 September 2016 at 22:59:53 UTC, Jonathan Marler 
wrote:
On Monday, 19 September 2016 at 22:17:34 UTC, Mathias Lang 
wrote:
2016-09-19 23:18 GMT+02:00 Jonathan Marler via Digitalmars-d < 
digitalmars-d@puremagic.com>:

[...]

No you can't. The example is wrong, but Stefan is right. 
Consider:

```
template Foo (T = string) { }

template TakesAlias(alias Sym) {}

alias TakesAlias!(Foo) Bar;
```

In this context, is `TakesAlias` instantiated with the 
template or the template instantiation ?

It is essentially the same category of problems as when trying 
to use a parameterless-functions, sometime you end up calling 
it because of the optional parenthesis. Except that for 
functions we can use `&` or `typeof`.

Good example, thanks for the information.

Maybe the compiler can do more works to make the code more 
readable. Here are my examples:

template EventHandler(T=Object)
{
   alias EventHandler = void delegate(T sender);
}


void test01(EventHandler handler) // Error
{
  // It's what I want. However, it doesn't work.
}

void test02(EventHandler!() handler)
{
  // It works. Howerve, it ...
}

void test03()(EventHandler handler)
{
  // It works too. Howerve, it ...
}

void test04(EventHandler!string handler)
{
  // It's OK.
}