slembckeMar 10

Had another conversation about pass-by-ref vs pass-by-value and why passing an object in something like C# or JS doesn't copy the object. Feels like this comes up every few months.

Always takes a bit of a struggle to explain what a pointer is to someone who's programmed for years without ever using one directly.

Obviously not a big problem, but it always makes me wonder what actually makes for the better abstraction.

Show threadtoerrorMar 10
@slembcke They've never modified a struct and wondered why the change isn't visible up the stack?
( I label my structs SName nowardays because otherwise they appear to be objects to all intents and purposes unless you look at the definition )
Show threadslembcke
@toerror Oh, no that's exactly it. This time the conversation went something like "I always forget that (C#) objects are pass-by-reference and structs are pass-by-value." Which then led into further confusion about what an object reference/pointer/whatever was vs what pass-by-reference means. I brought up the idea of using the ref keyword on a object, and what that would do. There was a bit of an "oooooh..." moment.
Mar 10 at 6:32pmWeb
Show threadbcaceMar 10
@slembcke @toerror i once made a small language where each function had two argument lists, one for passing by value, and another for by ref, so it was clear even at call site which is which
Show threadbcaceMar 10
@slembcke @toerror so declaration was something like `func f(int byval)(int byref)`, and then call would be `byref.f(byval)`, a little awkward, but clear once you get used to it
Show threadslembckeMar 11
@bcace @toerror How do you pass the byref argument?
Show threadbcaceMar 11
@slembcke @toerror that's the `byref` in `byref.f(byval)`, you can have multiple byref args in declaration: `func f()(int byref1, int byref2)`, and at call site: `(var1, var2).f()`
Show threadbcaceMar 11
@slembcke @toerror and if it's a func with only byval args then it's just `func f(int byval)`, and then call `f(var1)`