Hi,

Code here:
https://gist.github.com/grogancolin/066a8a8c105fa473dfee961e2481a30e

Basically, it seems when a template has an alias parameter like

class Node(T, alias func = (T t => t*t))(){
//whatever
}

//instantiate
Node!(int) intNode;
Node!(float) floatNode;   // fails as lambda func expects an int.

Am I doing something wrong or is this a bug?

On 08/30/2016 10:41 PM, wobbles wrote:
> class Node(T, alias func = (T t => t*t))(){
> //whatever
> }
>
> //instantiate
> Node!(int) intNode;
> Node!(float) floatNode;   // fails as lambda func expects an int.
>
> Am I doing something wrong or is this a bug?

Proper test case:

----
class Node(T, alias func = (T t) => t*t)
{
    void method() { func(T.init); }
}

//instantiate
Node!(int) intNode;
Node!(float) floatNode;   // fails as lambda func expects an int.
----

Looks like a bug to me. Similar to this:
https://issues.dlang.org/show_bug.cgi?id=14501

On Tuesday, 30 August 2016 at 20:55:20 UTC, ag0aep6g wrote:
> On 08/30/2016 10:41 PM, wobbles wrote:
>> class Node(T, alias func = (T t => t*t))(){
>> //whatever
>> }
>>
>> //instantiate
>> Node!(int) intNode;
>> Node!(float) floatNode;   // fails as lambda func expects an int.
>>
>> Am I doing something wrong or is this a bug?
>
> Proper test case:
>
> ----
> class Node(T, alias func = (T t) => t*t)
> {
>     void method() { func(T.init); }
> }
>
> //instantiate
> Node!(int) intNode;
> Node!(float) floatNode;   // fails as lambda func expects an int.
> ----
>
> Looks like a bug to me. Similar to this:
> https://issues.dlang.org/show_bug.cgi?id=14501

Yeah. Looks related.

I'll have to try find a workaround for now :/

On 08/30/2016 11:28 PM, wobbles wrote:
> I'll have to try find a workaround for now :/

This seems to work and isn't too ugly:

----
class Node(T, alias func) {/*...*/}
alias Node(T) = Node!(T, (T t) => t*t);
----

On 08/30/2016 11:28 PM, wobbles wrote:
> I'll have to try find a workaround for now :/

This also seems to work, but has a slightly different meaning:

----
class Node(T, alias func = t => t*t) {/* ... */}
----

The default func is a template here. Equivalent to this:

----
auto square(T)(T t) { return t*t; }
class Node(T, alias func = square) {/* ... */}
----

On Tuesday, 30 August 2016 at 21:35:29 UTC, ag0aep6g wrote:
> On 08/30/2016 11:28 PM, wobbles wrote:
>> I'll have to try find a workaround for now :/
>
> This seems to work and isn't too ugly:
>
> ----
> class Node(T, alias func) {/*...*/}
> alias Node(T) = Node!(T, (T t) => t*t);
> ----

Excellent - thanks for these.
This one will work for me :)

I was going to do something messy with a nested template and some static ifs. But, complicated things are complicated. This is much easier.
Thanks!