Copy constructors for lazy initialization
SeeWebsiteForEmail at erdani.org
Fri May 28 18:26:50 PDT 2010
Walter has had a great idea last night: allow classes to define
this(ref S src);
where S is the name of the struct being defined, as an alternative for
The result would be a function similar with a C++ copy constructor.
Such an abstraction allows us to perform lazy initialization in a way
that allows the kind of problems associated with non-shared hash tables:
void foo(int[int] x)
x = 5;
assert(x == 5); // fails
If you change the first line of main() with
int[int] x = [ 42:42 ];
the assert passes.
The idea of the copy constructor is to lazy initialize the source and
the target if the source has null state. That would take care of this
problem and the similar problems for shared state.
There is still a possibility to call a method against an object with
null state. I think that's acceptable, particularly because lazy
initialization saves some state allocation.
What do you think?
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