What am I missing? Pure constructor behaves differently when assigning string member
I can't find a way to use a pure constructor to create both
mutable and immutable instances of the same class, when one of
the fields I assign is a string.
This works fine:
class A
{
int value;
this(int value_) pure
{
this.value = value_;
}
}
auto a_mutable = new A(1);
auto a_immutable = new immutable A(2);
But if I change the field to a string, I get a compilation error:
class B
{
string value;
this(string value_) pure
{
this.value = value_;
}
}
auto b_mutable = new B(foo);
auto b_immutable = new immutable B(bar);
giving a compilation error for the last row:
Error: mutable method B.this is not callable using a immutable
object
forcing me to use two separate constructors, which works fine:
class B
{
string value;
this(string value_)
{
this.value = value_;
}
this(string value_) immutable
{
this.value = value_;
}
}
The question is: am I missing something that would make it
possible to use a pure constructor in this case, or is it simply
not possible?
Re: What am I missing? Pure constructor behaves differently when assigning string member
On Saturday, 29 November 2014 at 09:41:00 UTC, jostly wrote: I can't find a way to use a pure constructor to create both mutable and immutable instances of the same class, when one of the fields I assign is a string. After poking around a bit, I believe it is caused by issue #10012 https://issues.dlang.org/show_bug.cgi?id=10012 : This is current dmd implementation limitation. In complex cases dmd cannot detect that the constructor generates unique object. So my question then becomes, how can I generate an unique object from the string? I tried using .idup on the incoming string, but that didn't help. Or is it simply still a problem of _detecting_ it for the compiler?
