Extend the call site default argument expansion mechanism?

[rikki cattermole]

On 11/05/2018 2:33 AM, Yuxuan Shui wrote:
> On Thursday, 10 May 2018 at 14:28:39 UTC, JN wrote:
>> On Thursday, 10 May 2018 at 14:15:18 UTC, Yuxuan Shui wrote:
>>> [...]
>>
>> For things like this you can use the OOP Factory pattern, pseudocode:
>>
>> class DataStructureFactory
>> {
>>   this(Allocator alloc)
>>   {
>>     this.alloc = alloc;
>>   }
>>
>>   Allocator alloc;
>>
>>   DataStructure createDataStructure(...)
>>   {
>>     return new DataStructure(..., alloc)
>>   }
>> }
>>
>> DataStructureFactory factory = new DataStructureFactory(new 
>> SomeAllocator())
>> auto data1 = factory.createDataStructure(...)
>> auto data2 = factory.createDataStructure(...)
>> auto data3 = factory.createDataStructure(...)
> 
> But doing it with default argument expansion saves you 1 allocation, has 
> 1 less type, while being just as readable. I think that's a win.

class -> struct, now it is back to 1 allocation.