Re: Class member initialization with new points to a single instance?
On Wednesday, 9 June 2021 at 18:12:01 UTC, Gregor Mückl wrote:
On Wednesday, 9 June 2021 at 18:04:54 UTC, evilrat wrote:
On Wednesday, 9 June 2021 at 17:56:24 UTC, Gregor Mückl wrote:
Consider the following code:
```d
class Foo { }
class Bar { Foo foo = new Foo(); }
void main()
{
Bar b1 = new Bar();
Bar b2 = new Bar();
assert(b1.foo != b2.foo);
}
```
The assert fails. This is completely surprising to me. Is
this actually expected?
By design.
What you see is CTFE instance shared through class member
initializer.
Use Bar ctor instead if you want them to be unique.
Yep, confusing for the first time.
My two cents:
I think this should be changed because all other common
languages that support equivalent syntax have settled on
runtime initialization for this. But it's probably too deeply
embedded into the language now. :(
Can we add (enforcement) `static` in this case, to make it clear.
It's so confusing.
Re: Class member initialization with new points to a single instance?
On Wednesday, 9 June 2021 at 18:04:54 UTC, evilrat wrote:
On Wednesday, 9 June 2021 at 17:56:24 UTC, Gregor Mückl wrote:
Consider the following code:
```d
class Foo { }
class Bar { Foo foo = new Foo(); }
void main()
{
Bar b1 = new Bar();
Bar b2 = new Bar();
assert(b1.foo != b2.foo);
}
```
The assert fails. This is completely surprising to me. Is this
actually expected?
By design.
What you see is CTFE instance shared through class member
initializer.
Use Bar ctor instead if you want them to be unique.
Yep, confusing for the first time.
My two cents:
I think this should be changed because all other common languages
that support equivalent syntax have settled on runtime
initialization for this. But it's probably too deeply embedded
into the language now. :(
Re: Class member initialization with new points to a single instance?
On Wednesday, 9 June 2021 at 17:56:24 UTC, Gregor Mückl wrote:
Consider the following code:
```d
class Foo { }
class Bar { Foo foo = new Foo(); }
void main()
{
Bar b1 = new Bar();
Bar b2 = new Bar();
assert(b1.foo != b2.foo);
}
```
The assert fails. This is completely surprising to me. Is this
actually expected?
By design.
What you see is CTFE instance shared through class member
initializer.
Use Bar ctor instead if you want them to be unique.
Yep, confusing for the first time.
Re: Class member initialization with new points to a single instance?
On Wednesday, 9 June 2021 at 17:56:24 UTC, Gregor Mückl wrote:
class Bar { Foo foo = new Foo(); }
This is a static initialization
The assert fails. This is completely surprising to me. Is this
actually expected?
Yes, it is expected if you are familiar with the spec.
All member = x things inside a class or struct declaration are
static initializers. These are CTFE'd into the same form as a
literal. So there's one instance of Foo there which is assigned
to the object member before the constructor runs.
For a runtime initialization, you use a constructor.
Class member initialization with new points to a single instance?
Consider the following code:
```d
class Foo { }
class Bar { Foo foo = new Foo(); }
void main()
{
Bar b1 = new Bar();
Bar b2 = new Bar();
assert(b1.foo != b2.foo);
}
```
The assert fails. This is completely surprising to me. Is this
actually expected?
