On Sunday, 29 December 2013 at 18:40:07 UTC, Maxim Fomin wrote:
On Sunday, 29 December 2013 at 16:22:04 UTC, Ritu wrote:
I have a struct that wraps a class object and lazily
initializes it. Now in case the struct instance is passed as
an argument to a function and it has not been initialized yet,
the default copy constructor and the postblit do not offer a
possibility to initialize the class object before copying.
Why this is a problem? You can create function which return
class field from struct wrapper and make such function alias
this, in addition postblit should allocate new class. The fact
that original struct may have null value is irrelevant if
copying is made correctly.
It's a problem for "reference semantic structs" that need to be
initialized. This is actually a "well know" and often encountered
problem.
It strikes things like Appende, Array, and also built in AA's.
void foo(Appender!(int[]) app)
{
app.put(1);
}
void main()
{
Appender!(int[]) app1;
Appender!(int[]) app2 = appender!(int[]);
foo(app1);
foo(app2);
assert(app1.data == [1]); //Fails
assert(app2.data == [1]); //Passes
}
