DIP 45 - approval discussion

[Andrei Alexandrescu]

On 11/12/13 3:05 PM, Jakob Ovrum wrote:
> On Tuesday, 12 November 2013 at 22:36:22 UTC, Timon Gehr wrote:
>> - Every class in any imported module will need to show up in the
>> generated code even if it is never used unless global static analysis
>> is carried out on arguments to Object.factory.
>>
>> - If I know the fully qualified name of a class, there are better ways
>> to instantiate this class than passing a string containing that name
>> to Object.factory in order to call the default constructor.
>>
>> - The functionality provided by Object.factory is trivially replaced
>> by a solution more specifically tailored to the problem at hand using
>> compile-time reflection.
>
> + 1.
>
> To test, I made a Factory template that works like this:
>
> ---
> unittest
> {
>      import std.traits : fullyQualifiedName;
>
>      interface I {}
>      class A : I {}
>      class B : I {}
>
>      alias f = Factory!(I, A, B);

Stopped reading here, and everybody should. There is a thorough 
treatment of object factories in "Modern C++ Design" which I recommend 
not because I wrote it, but because it's thorough. Part of it is to show 
why the approach above is marred by dependency issues and should often 
be avoided.


Andrei