struct vs. class containers
bearophile
bearophileHUGS at lycos.com
Sun May 23 15:06:32 PDT 2010
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
> 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
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