Default Template Instantiation
Heromyth
bitworld at qq.com
Thu May 17 08:37:01 UTC 2018
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 at 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.
}
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