Jeremie Pelletier wrote: > You cannot have static array be ref or out. You must use int[] arr instead > and let the caller specify the length. > > Array in D are already references to their data, it's a 8bytes (or 16bytes > on x64) value containing a pointer and a length.
Ok, this I got correct :) >So the following prototype: void func(<none>/in/ref/out int[] arr); > > would have the following semantics: > > "<none>" copies the array reference, the referenced data is mutable. > Modifying the local reference does not change the caller's reference. Modifying the local referenced data does not change the caller's referenced data. So only if the referenced data is mutated, a copy will be made? Test seems to back this up. > "in" copies the array reference, the local reference AND the referenced > data are immutable in the method's scope. What, there is a difference between <none> and "in" ?? Where can I about read this? In the example "int foo(int x, ..." on the functions page x is "in". Are we maybe talking about a different D? D1 I really really wish to understand this stuff. <info> I know about how in c a function stack is created. > "ref" passes a reference to the caller's array reference, the referenced > data is mutable. Modifying the local reference also changes the caller's > reference. Same as <none> except that it doesn't create a copy on mutate? > "out" passes a reference to the caller's array reference. The referenced > array reference is zeroed and can be modified by the local reference. Compared to returning a locally(to the function) created array, here no allocation might be needed if the passed array is big enough. > > If you want a mutable reference to an immutable view on the referenced > data, use const(int)[], which can also be ref or out. out const(int)[] will create a array of zero's which you cannot change? Why isn't there a nice table about this? columns: local reference/data with/without mutation, caller reference/data with/without mutation rowns: <none>, in, out, ref cells: array.ptr/length/data Or, where should I put it after creating it. > void func(in/out/ref int i) > > "<none>" would be a mutable copy. > "in" would be immutable copy. I can't get over the idea that in and none aren't the same Really, D1? :D In my test program I can change local i using "in" > "out" is a reference to the caller's int initialized to 0. > "ref" is a reference to the caller's int. > "in" and "const" are only really useful with types which are already > references, such as pointers, arrays and objects. Hope I got it right..
