On Sunday, 25 November 2012 at 15:27:53 UTC, comco wrote:
A!B(...) defines a struct A with B typed in as Method, so call
to method(s); is the same as B(string)
Why is that? Here method is an instance of the type Method, not
the type Method itself, so by saying `method(s)` we can't mean
a constructor. Something very strange happens...
I have a simpler example now:
Welcome to D structs creation puzzle.
skipped
If you change return type from void to e.x. int, dmd will still
complain "Error: need 'this' to access member opCall".
There are two problems here: firstly, by some reason dmd does not
distinguish between static and non static methods in a sense that
it allows to call static method on instance and takes into
account non-static methods with expression operating on types
(like this case).
Secondly, and again by some reason three "semantic things" such
as struct literals, struct constructors and opCalls use same
syntax like "S()" (let alone it may be non-member function). This
makes their priority order an issue - for 2.060 version it is:
1)opCall 2)ctor 3)literal. This is why dmd complains about
"A.opCall (int i) is not callable using argument types ()": it
recognizes an opCall method, does not take into account
staticness and tries to convert A() into opCall invocation.
Recently I saw a major pull affecting this behavior, so in 2.061
the situation may be changed (I haven't bother to figure yet). In
practice this makes a tricky thing to understand what S() is and
creates a problem when you e.x. heavily use struct ctor, write
opCall method and everything breaks due to dmd tries now to call
opCall instead of ctor.
