Re: Default initialization of structs?
On Friday, 17 June 2016 at 11:10:12 UTC, Gary Willoughby wrote:
Thanks, I forgot to mention I'm also doing lots of other stuff
in the constructor to private fields too.
struct Foo(T)
{
private int _bar;
private void* _baz;
this(int bar = 8)
{
this._bar = bar;
this._baz = malloc(this._bar);
}
}
So I have to at least run a constructor.
Structs cannot have a default constructor; .init is required to
be a valid state (unless you @disable default construction). This
is a deliberate language restriction, although you can argue
about its value.
What you can do as a workaround is to provide a public static
factory method while disabling default construction.
— David
Re: Default initialization of structs?
On Friday, 17 June 2016 at 10:50:55 UTC, Gary Willoughby wrote: I have a struct where I need to perform default initialization of some members but the compiler doesn't allow to define a default constructor which allow optional arguments. This is a fairly recent change (2.068->2.069 or 2.070), so if you browse the release notes you may be able to figure out exactly why this is not allowed. -Johan
Re: Default initialization of structs?
The Factory-Pattern would be a good idea.
Re: Default initialization of structs?
On Friday, 17 June 2016 at 10:53:40 UTC, Lodovico Giaretta wrote:
struct Foo(T)
{
private int _bar = 1;
this(int bar)
{
this._bar = bar;
}
}
auto foo = Foo!(string)();
This should do the trick.
Thanks, I forgot to mention I'm also doing lots of other stuff in
the constructor to private fields too.
struct Foo(T)
{
private int _bar;
private void* _baz;
this(int bar = 8)
{
this._bar = bar;
this._baz = malloc(this._bar);
}
}
So I have to at least run a constructor.
Re: Default initialization of structs?
On Friday, 17 June 2016 at 10:50:55 UTC, Gary Willoughby wrote:
I have a struct where I need to perform default initialization
of some members but the compiler doesn't allow to define a
default constructor which allow optional arguments.
struct Foo(T)
{
private int _bar;
this(int bar = 1)
{
this._bar = bar;
}
}
auto foo = Foo!(string) // error
Are there any patterns or idioms I could use to get the desired
result? Or is it just the case if I use a constructor I have to
pass values to it?
struct Foo(T)
{
private int _bar = 1;
this(int bar)
{
this._bar = bar;
}
}
auto foo = Foo!(string)();
This should do the trick.
Default initialization of structs?
I have a struct where I need to perform default initialization of
some members but the compiler doesn't allow to define a default
constructor which allow optional arguments.
struct Foo(T)
{
private int _bar;
this(int bar = 1)
{
this._bar = bar;
}
}
auto foo = Foo!(string) // error
Are there any patterns or idioms I could use to get the desired
result? Or is it just the case if I use a constructor I have to
pass values to it?
