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digitalmars.D - One of the thing I like in D

reply Boaz Ampleman <ba 1234.de> writes:
```d
void main()
{
     auto a = 0;
     auto b = 0;
     auto c = 1;

     auto ptr = &(c ? a : b);
     *ptr = 8;
     assert(a == 8);
     ptr = &(c ? b : a);
     *ptr = 2;
     assert(a + b == 10);
}
```

It's just beautiful
Oct 07
next sibling parent reply Dom Disc <dominikus scherkl.de> writes:
On Monday, 7 October 2024 at 20:03:46 UTC, Boaz Ampleman wrote:

 ```d
 void main()
 {
     auto a = 0;
     auto b = 0;
     auto c = 1;

     auto ptr = &(c ? a : b);
     *ptr = 8;
     assert(a == 8);
     ptr = &(c ? b : a);
     *ptr = 2;
     assert(a + b == 10);
 }
 ```

 It's just beautiful


But why pointers?

```d
void  safe main()
{
     auto a = 0;
     auto b = 0;
     auto c = 1;

     (c ? a : b) = 8;
     assert(a == 8);
     (c ? b : a) = 2;
     assert(a + b == 10);
}
```
Oct 08
next sibling parent Boaz Ampleman <ba 1234.de> writes:
On Tuesday, 8 October 2024 at 08:38:15 UTC, Dom Disc wrote:

 On Monday, 7 October 2024 at 20:03:46 UTC, Boaz Ampleman wrote:

 ```d
 void main()
 {
     auto a = 0;
     auto b = 0;
     auto c = 1;

     auto ptr = &(c ? a : b);
     *ptr = 8;
     assert(a == 8);
     ptr = &(c ? b : a);
     *ptr = 2;
     assert(a + b == 10);
 }
 ```

 It's just beautiful


 But why pointers?

 [...]


yeah sorry, that missed a bit of comments. Here there are: the 
point was that the conditional expression yields a lvalue, hence 
it's candidate to be a sub-expression of the address expression. 
That is just something I had never seen before. I just wanted to 
share the joy ;)
Oct 08
prev sibling parent Imperatorn <johan_forsberg_86 hotmail.com> writes:
On Tuesday, 8 October 2024 at 08:38:15 UTC, Dom Disc wrote:

 On Monday, 7 October 2024 at 20:03:46 UTC, Boaz Ampleman wrote:

 ```d
 void main()
 {
     auto a = 0;
     auto b = 0;
     auto c = 1;

     auto ptr = &(c ? a : b);
     *ptr = 8;
     assert(a == 8);
     ptr = &(c ? b : a);
     *ptr = 2;
     assert(a + b == 10);
 }
 ```

 It's just beautiful


 But why pointers?

 ```d
 void  safe main()
 {
     auto a = 0;
     auto b = 0;
     auto c = 1;

     (c ? a : b) = 8;
     assert(a == 8);
     (c ? b : a) = 2;
     assert(a + b == 10);
 }
 ```


That's kinda flexible actually
Oct 08
prev sibling next sibling parent Walter Bright <newshound2 digitalmars.com> writes:
Yup. It's designed to look good!
Oct 09
prev sibling parent reply Per =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:
On Monday, 7 October 2024 at 20:03:46 UTC, Boaz Ampleman wrote:

 ```d
 void main()
 {
     auto a = 0;
     auto b = 0;
     auto c = 1;

     auto ptr = &(c ? a : b);
     *ptr = 8;
     assert(a == 8);
     ptr = &(c ? b : a);
     *ptr = 2;
     assert(a + b == 10);
 }
 ```

 It's just beautiful


With next dmd you can use use ref variables aswell as

```d
void main() {
     auto a = 0;
     auto b = 0;
     const c = 1;

     ref ptr = (c ? a : b);
     ptr = 8;
     assert(a == 8);
     ptr = (c ? b : a);
     ptr = 2;
     assert(b == 2); 			// why does this fail??
}
```

But for some reason the last statement doesn't behave as I 
believe it should. Is this behavior expected?

For reference see 
https://dlang.org/changelog/pending.html#dmd.reflocal.
Oct 11
next sibling parent user1234 <user1234 12.de> writes:
On Friday, 11 October 2024 at 23:04:20 UTC, Per Nordlöw wrote:

 With next dmd you can use use ref variables aswell as

 ```d
 void main() {
     auto a = 0;
     auto b = 0;
     const c = 1;

     ref ptr = (c ? a : b);
     ptr = 8;
     assert(a == 8);
     ptr = (c ? b : a);
     ptr = 2;
     assert(b == 2); 			// why does this fail??
 }
 ```

 But for some reason the last statement doesn't behave as I 
 believe it should. Is this behavior expected?

 For reference see 
 https://dlang.org/changelog/pending.html#dmd.reflocal.


This has to be a bug ;)
Oct 11
prev sibling parent Dave P. <dave287091 gmail.com> writes:
On Friday, 11 October 2024 at 23:04:20 UTC, Per Nordlöw wrote:

 On Monday, 7 October 2024 at 20:03:46 UTC, Boaz Ampleman wrote:

 [...]

 It's just beautiful


 With next dmd you can use use ref variables aswell as

 ```d
 void main() {
     auto a = 0;
     auto b = 0;
     const c = 1;

     ref ptr = (c ? a : b);
     ptr = 8;
     assert(a == 8);
     ptr = (c ? b : a);
     ptr = 2;
     assert(b == 2); 			// why does this fail??
 }
 ```

 But for some reason the last statement doesn't behave as I 
 believe it should. Is this behavior expected?

 For reference see 
 https://dlang.org/changelog/pending.html#dmd.reflocal.


`ref` can’t change what it is pointing to. So the second ternary 
is just assigning through the reference, not re-binding the 
reference.

If you re-write the example in terms of pointers, it is 
equivalent to:

```d
void main() {
     auto a = 0;
     auto b = 0;
     const c = 1;

     int* ptr = &(c ? a : b);
     *ptr = 8;
     assert(a == 8);
     *ptr = (c ? b : a);
     *ptr = 2;
}
```
Oct 11