struct vs. class containers

[Jacob Carlborg]

On 2010-05-24 00.06, bearophile wrote:
> Andrei Alexandrescu:
>
>> 1. Using a class makes implementing members easier because there's no
>> need to do work through an additional member. With a struct, you need a
>> pimpl approach. For example:
>>
>> struct Array {
>>       struct Impl {
>>           ...
>>       }
>>       Impl * impl;
>>       ...
>>       @property length() const { return impl->length; }
>>       ...
>> }
>
> I am far from being an expert as you, and while I have read about the PImpl in C++, I don't understand what you are saying here. I am sorry.
>
>
>> 3. The creation syntaxes are different.
>
> In C# you use 'new' for both structs allocated on the stack and classes allocated on the heap:
> http://msdn.microsoft.com/en-us/library/51y09td4%28VS.71%29.aspx

I've never liked that, always thinking that it maybe allocating on the heap.

>> Let me note that I have reached the conclusion that containers should
>> be at best reference types, with a meta-constructor Value!(C) that takes
>> a container C and makes it into a value type.
>
> Does Value!() use static introspection and placement new to instantiate the given class on the stack? :-)
>
> Bye and thank you,
> bearophile


-- 
/Jacob Carlborg