Return parameter passing in Julia

Question

If a Julia function returns an array, is the reference returned or a copy?

function pass(A::Matrix)
   return A
end

A real example is reshape:

reshape(A, dims) Create an array with the same data as the given array, but with different dimensions. An implementation for a particular type of array may choose whether the data is copied or shared.

How does the implementation determine whether data is copied or shared?

Answer 1

The pass function above returns by reference, http://julia.readthedocs.org/en/latest/manual/arrays/ .

There is a bit more to the reshape example. For full arrays the reshaped array is a new array object that shares the same data. But keep in mind that there are plenty of specialized array types. The docs warn you not to rely on that because for example for a future implementation of immutable fixed sized arrays a different reshape mechanism could be used.