Re: Proper desctructor for an class containing dynamic array of objects
On Friday, 14 June 2019 at 11:10:58 UTC, rumbu wrote: On Friday, 14 June 2019 at 07:52:24 UTC, Marco de Wild wrote: On Thursday, 13 June 2019 at 16:08:52 UTC, Mike wrote: Opposed to Java, D's member variables are static initialised. Is there any documentation about this? I find it unexpected. https://dlang.org/spec/class.html#static-constructor «All member initializations must be determinable by the compiler at compile time, hence there is no order-of-evaluation dependency for member initializations, and it is not possible to read a value that has not been initialized. Dynamic initialization is performed by a static constructor»
Re: Proper desctructor for an class containing dynamic array of objects
On Friday, 14 June 2019 at 07:52:24 UTC, Marco de Wild wrote: On Thursday, 13 June 2019 at 16:08:52 UTC, Mike wrote: Opposed to Java, D's member variables are static initialised. Is there any documentation about this? I find it unexpected.
Re: Proper desctructor for an class containing dynamic array of objects
On Thursday, 13 June 2019 at 16:08:52 UTC, Mike wrote:
Hi,
my name is Mike and I'm new to D (coming from a Javabackground)
and for fun I'm trying to learn D now.
I created a simple class
class Block {
int a, b;
this() {}
}
And now I have a dynamic array of objects of this class in
another class:
class Foo {
Block[] array = new Block[](10);
this() {
for (int i = 0; i < array.length; i++) {
array[i] = new Block();
}
}
}
How would a proper destructor of class Foo look like?
Is it enough to set "array" to null? Or do I have to set every
element of the array to null and then the array, or nothing of
that at all because the garbage collecter collects it, if the
reference to Foo is set to null?
Opposed to Java, D's member variables are static initialised.
There is one default value for "array" that is shared between all
instances of Foo. This allows for compiler optimisations of
primitives (baking in a int value of 5 into the class definition,
but gives unexpected behaviour for reference types.
https://run.dlang.io/is/UNp5Al
In this example, two instances of Foo are created. The
constructor is run both times. However, they act on the same
array object. So initialisation of the second Foo will modify
references data of the first Foo. As a check, the first object of
both Foos are compared by reference.
Java allows you to define a block of code in your class that is
run on construction, e.g.
public class JavaClass {
{
doStuff();
}
int x = initializeX();
}
It makes for fun questions on things like OCA certificates.
However, D doesn't allow that. All initialisation code is placed
in the constructor, e.g.
this() {
array = new Block[](10);
// ...
}
(Of course you can call other methods from there. In fact,
constructor rules are slightly relaxed compared to Java.)
Re: Proper desctructor for an class containing dynamic array of objects
On Thursday, 13 June 2019 at 16:08:52 UTC, Mike wrote: How would a proper destructor of class Foo look like? Is it enough to set "array" to null? Or do I have to set every element of the array to null and then the array, or nothing of that at all because the garbage collecter collects it, if the reference to Foo is set to null? Nothing at all, GC will take care. As long as your Block class doesn't create any system resources that must be discarded.
Re: Proper desctructor for an class containing dynamic array of objects
On Thursday, 13 June 2019 at 16:08:52 UTC, Mike wrote: or nothing of that at all because the garbage collecter collects it, if the reference to Foo is set to null? That. [The init loop can be shortened to `foreach (ref b; array) b = new Block();`.]
Proper desctructor for an class containing dynamic array of objects
Hi,
my name is Mike and I'm new to D (coming from a Javabackground)
and for fun I'm trying to learn D now.
I created a simple class
class Block {
int a, b;
this() {}
}
And now I have a dynamic array of objects of this class in
another class:
class Foo {
Block[] array = new Block[](10);
this() {
for (int i = 0; i < array.length; i++) {
array[i] = new Block();
}
}
}
How would a proper destructor of class Foo look like?
Is it enough to set "array" to null? Or do I have to set every
element of the array to null and then the array, or nothing of
that at all because the garbage collecter collects it, if the
reference to Foo is set to null?
