On Monday, 8 June 2015 at 09:20:06 UTC, Ola Fosheim Grøstad wrote:
On Monday, 8 June 2015 at 06:35:33 UTC, Jonathan M Davis wrote:
On Monday, 8 June 2015 at 06:04:23 UTC, Tofu Ninja wrote:
No its definitely not something that alot of people seem to
care about, but I always found it odd that constructors get
certain special casing like this.
I expect that it originally comes down to the fact that
constructors aren't polymorphic and _can't_ be polymorphic.
They can if you use type variables. Type variables can be
virtual too.
When you override a function, you're overriding the one in the
base class and replacing its implementation. You can choose to
call the base class' version of the function, but you don't
have to. You're dynamically replacing a function.
Conceptually you should. In Simula's successor Beta you had to,
but you had "inner" inheritance opposed to Simula/C++ "outer"
inheritance. E.g. the logic of the subclass is executed by the
superclass. It is much cleaner, actually.
So, yes, constructors _are_ fundamentally different from other
functions. And the inheritance that you get with constructors
is not at all what you get when you override a function.
They're at most superficially similar. And older languages
such as C++98 and Java don't have inherited constructors.
They're a relatively new idea.
Let's not rewrite history, shall we? Constructors are not
fundamentally different from other functions by nature. In
minimal OO languages there is no significant difference between
the definition of a class/constructor and a function.
Yep, in Modula-3 and Oberon, one even has to create the VMT
explicitly.
--
Paulo
