What's the correct way of creating an instance of class in D?
Tejas
notrealemail at gmail.com
Thu Nov 3 17:46:02 UTC 2022
On Thursday, 3 November 2022 at 15:40:02 UTC, H. S. Teoh wrote:
> On Thu, Nov 03, 2022 at 04:41:14AM +0000, Siarhei Siamashka via
> Digitalmars-d-learn wrote: [...]
>> ```D
>> @safe:
>> import std.stdio;
>> class A {
>> void foo() { writeln("foo"); }
>> }
>> void main() {
>> auto a1 = new A;
>> a1.foo(); // prints "foo"
>> A a2;
>> a2.foo(); // Segmentation fault
>> }
>> ```
> [...]
>
> D does not have the equivalent of C++'s allocating a class
> instance on the stack. In D, all class instances are allocated
> on the heap and class variables are references to them.
> Declaring an instance of A as a local variable initializes it
> to the null reference, so invoking a method on it rightly
> segfaults.
>
>
> T
I think his main problem will go away if the code just refuses to
compile, since it's known at compile time that one is trying to
dereference a `null` pointer
Check my post, `A& a;` refuses to compile in C++20 atleast,
asking to be explicitly initialized, thus averting the problem
altogether
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