Op 25-09-17 om 21:44 schreef Ned Batchelder: > > Wikipedia has the right definition of call by reference > (https://en.wikipedia.org/wiki/Evaluation_strategy#Call_by_reference): > > /Call by reference/ (also referred to as /pass by reference/) is an > evaluation strategy where a function receives an implicit reference > <https://en.wikipedia.org/wiki/Reference_%28computer_science%29> to > a variable used as argument, rather than a copy of its value. This > typically means that the function can modify (i.e. assign to > <https://en.wikipedia.org/wiki/Assignment_%28computer_science%29>) > the variable used as argument—something that will be seen by its > caller. > > The key idea here is that it is a reference to a *variable* that is > passed, not a reference to a value. Python has no references to > variables, so it cannot support call by reference. Because Python > passes references to values, it is easy to call it "call by > reference," but that is not what the term means. > > The Wikipedia definition unfortunately includes "rather than a copy of > its value," as if those are the only two options (a common > misunderstanding). > > Elsewhere in this thread, someone asserted that to be call by > reference, you have to be able to write a swap(x,y) function. True > call-by-reference would make this possible. Python cannot do it.
I can write a swap function for lists in python. Can I now conclude that lists are passed by reference? -- Antoon Pardon. -- https://mail.python.org/mailman/listinfo/python-list
