On 08/11/2012 01:24 PM, Marco Leise wrote:
Am Fri, 10 Aug 2012 15:56:53 +0200 schrieb Timon Gehr<timon.g...@gmx.ch>:int eval(scope Expr* e){ final switch(e.tag) with(Expr.Tag){ case val: return e.i; case plus: return eval(e.a) + eval(e.b); case minus: return eval(e.a) - eval(e.b); } }Can you quickly explain the use of scope here? Does that mean "I wont keep a reference to e"?
It means "I won't keep a reference to *e", but I assume that is what was meant.
What are the implications?
The caller has some confidence that passing a pointer to stack- allocated data is safe.
Does scope change the method signature?
Yes. It is eg. impossible to override a method that has a scope parameter with a method that does not have a scope parameter.
Does the compiler enforce something?
In this case and currently, it is merely documentation. I think it should be enforced and cast(scope) should be added to allow non-@safe code to escape the conservative analysis.
Will generated code differ?
Only the mangled symbol name will differ. (unlike when scope is used on delegate parameters, in this case it prevents closure allocation at the call site.)
Does it prevent bugs or is it documentation for the user of the function?
It is just documentation, both for the user and the maintainer.
Thanks in advance for some insight!
