When D is not nice

[Bill Baxter]

Frank Benoit wrote:
> Simen Kjaeraas schrieb:
>> Frank Benoit <keinfarbton at googlemail.com> wrote:
>>
>>> String concatenation in Java:
>>>
>>> "abc " + a + " bla";
>>>
>>> where a is an interface ref.
>>>
>>> Ported to D, this look like this:
>>>
>>> "abc " ~ (cast(Object)a).toString ~ " bla";
>>>
>>> This are 3 steps more:
>>> 1.) explicit cast to Object (interface/class compatibility!)
>>> 2.) explicit call to toString
>>> 3.) put additional parentheses
>>>
>>> I would be happy if we could remove all three of this annoying points.
>>
>>
>>
>> interface A
>> {
>>     string opCat(string rhs);
>>     string opCat_r(string lhs);
>> }
>>
>> class B : A
>> {
>>     string opCat(string rhs)
>>     {
>>         return toString() ~ rhs;
>>     }
>>
>>     string opCat_r(string lhs)
>>     {
>>         return lhs ~ toString();
>>     }
>>
>>     string toString()
>>     {
>>         return SomeString;
>>     }
>> }
>>
>> This works for me.
>>
>> -- Simen
> 
> My intention was not to ask how to solve it for a certain interface.
> Instead i was trying to show a flaw in the language design.
> 
> Even if i would add object.Object method to /every/ interface, then 
> still an interface ref is NOT implicit castable to an Object ref. And i 
> would need to reimplement all those methods in every class that 
> implements the interface.

That seems to be the price we pay for having interfaces that can be COM 
interfaces as well.  But I'm not sure why I should want to pay that 
price, having never had a need to call a COM interface in my life.

--bb