On Sunday, 23 February 2020 at 09:03:56 UTC, mark wrote:
Then this would not only help dscanner, but also make it clear
to programmers that the argument could be modified.
(This is done in Rust with f(&mut arg), and I certainly find it
helpful.)
C# also does it, and uses exactly the same keyword as D:
To use a ref parameter, both the method definition and the
calling method must explicitly use the ref keyword, as shown in
the following example.
https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/ref
Making it mandatory in D would cause code breakage and hamper
generic code, but like you suggest, making it optional is an
interesting idea. It can also enforce that something is actually
passed by ref to avoid accidental copies, which currently
requires manual checking. For example in std.format:
// force toString to take parameters by ref
static assert(!__traits(compiles, val.toString(s,
FormatSpec!Char())));
static assert(!__traits(compiles, val.toString(S(), f)));}
https://github.com/dlang/phobos/blob/fee0697a8328dc22258cf09753f39ad5984015db/std/format.d#L3887
