Re: Conditional Attributes
On Thursday, 20 February 2020 at 17:41:54 UTC, Dennis wrote:
On Tuesday, 18 February 2020 at 17:11:55 UTC, Marcel wrote:
Say I have a struct where every member function can either be
static or not depending on a template parameter. Is there a
simple way to do this?
The best I can think of is:
```
mixin template maybeStatic() {
void foo() {
// implementation
}
}
struct S(bool condition) {
static if (condition) {
static {
mixin maybeStatic;
}
} else {
mixin maybeStatic;
}
}
```
What do you need this for? It seems like an unusual situation
to me.
That will do, thank you!
I'm making an allocator library similar to what Andrei
Alexandrescu presented at CppCon. Since some allocators may not
have state, those that inherit* from them may need to have every
member function marked as static.
*I'm using mixins instead of inheritance.
Re: Conditional Attributes
On Friday, 21 February 2020 at 01:41:21 UTC, Steven Schveighoffer
wrote:
On 2/18/20 12:11 PM, Marcel wrote:
Hello!
Say I have a struct where every member function can either be
static or not depending on a template parameter. Is there a
simple way to do this? Like, for example:
struct Foo(Condition)
{
static if (Condition) static:
void Bar() {}
void Baz() {}
}
Since D conditional compilation must always be a valid
declaration or statement, you cannot do something like this.
The closest you can do is to use mixins, which means you have
to write everything inside strings.
It has been proposed quite a few times to have a way to
enable/disable attributes based on a compile-time boolean. But
it's never come close to getting included.
-Steve
That's a shame...
Re: Conditional Attributes
On 2/18/20 12:11 PM, Marcel wrote:
Hello!
Say I have a struct where every member function can either be static or
not depending on a template parameter. Is there a simple way to do this?
Like, for example:
struct Foo(Condition)
{
static if (Condition) static:
void Bar() {}
void Baz() {}
}
Since D conditional compilation must always be a valid declaration or
statement, you cannot do something like this.
The closest you can do is to use mixins, which means you have to write
everything inside strings.
It has been proposed quite a few times to have a way to enable/disable
attributes based on a compile-time boolean. But it's never come close to
getting included.
-Steve
Re: Conditional Attributes
On Tuesday, 18 February 2020 at 17:11:55 UTC, Marcel wrote:
Say I have a struct where every member function can either be
static or not depending on a template parameter. Is there a
simple way to do this?
The best I can think of is:
```
mixin template maybeStatic() {
void foo() {
// implementation
}
}
struct S(bool condition) {
static if (condition) {
static {
mixin maybeStatic;
}
} else {
mixin maybeStatic;
}
}
```
What do you need this for? It seems like an unusual situation to
me.
