Jarrett Billingsley wrote:
On Sat, Sep 26, 2009 at 9:32 PM, Andrei Alexandrescu
<seewebsiteforem...@erdani.org> wrote:
Consider two objects a and b with a of class type. Currently, the expression
a == b is blindly rewritten as a.opEquals(b). I argue it should be rewritten
into a call to an (imaginary/inlined) function equalObjects(a, b), with the
following definition:
bool equalObjects(T, U)(T a, U b) if (is(T == class))
{
static if (is(U == class))
{
if (b is null) return a is null;
if (a is null) return b is null;
}
else
{
enforce(a !is null);
}
return a.opEquals(b);
}
This hoists the identity test outside the opEquals call and also deals with
null references. What do you think?
I'm almost sure that C# does this already, and it's a useful behavior.
C# operator overloads are of the form:
public static ReturnType operator+(Arg1 arg1, Arg2 arg2) {}
Object.operator== is defined to call arg1.Equals(arg2) if arg1 isn't
null. But this isn't a feature of operator overloads.
Of course, with nonnull types, the check for null wouldn't even need
to exiiiiiiiist.... ;)
How clever and insightful of you!
