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I'm reluctant to bikeshed, but if I read your argument correctly, then technically everything is pass-by-value since even for references the actual reference (a

I'm reluctant to bikeshed, but if I read your argument correctly, then technically everything is pass-by-value since even for references the actual reference (a.k.a. pointer) is passed by value.

MaxBarraclough 5y ago
Pass-by-reference is distinct from passing a pointer by value. In my old comment [0] I gave example code fragments in C# to illustrate the difference. (C# supports both pass-by-value and pass-by-reference. It's like C++ in that regard, although the syntax is different.) > I'm reluctant to bikeshed This is the kind of topic where precise phrasing is important, so I wouldn't chalk it up as pedantry. It doesn't help that Java muddied the waters with its use of the word reference. [0] Here's the link again: https://news.ycombinator.com/item?id=23553574 https://news.ycombinator.com/item?id=23553574
- secondcoming 5y ago
  You've show a syntactic difference, not a functional difference. What does the 'ref' keyword change about how C# passes the argument to the function? I'd imagine (having zero C# experience) that it passes either a pointer, or an index, or an offset, to the function by value. It may also just copy the argument, pass it to the function, and then copy the copy back to the original argument (which would be daft).
  - MaxBarraclough 5y ago
    > You've show a syntactic difference, not a functional difference. Kinda, but that difference is important. We can say that C allows us to simulate pass-by-reference by using pointers. It's still true that the C language does not support pass-by-reference semantics. Taking the address of a variable is an operation that the C language permits us to do, yielding a new value (a pointer value). This isn't part of C's argument-passing functionality, though. > What does the 'ref' keyword change about how C# passes the argument to the function? The internals of C# compilers aren't really the point, but I believe .Net does it the copy-intensive way, copying to pass in and copying again to pass the new value back out. I don't think this a real performance problem though, unless you overuse the feature.

I'm reluctant to bikeshed, but if I read your argument correctly, then technically everything is pass-by-value since even for references the actual reference (a.k.a. pointer) is passed by value.

MaxBarraclough 5y ago

Pass-by-reference is distinct from passing a pointer by value. In my old comment [0] I gave example code fragments in C# to illustrate the difference. (C# supports both pass-by-value and pass-by-reference. It's like C++ in that regard, although the syntax is different.) > I'm reluctant to bikeshed This is the kind of topic where precise phrasing is important, so I wouldn't chalk it up as pedantry. It doesn't help that Java muddied the waters with its use of the word reference. [0] Here's the link again: https://news.ycombinator.com/item?id=23553574 https://news.ycombinator.com/item?id=23553574

secondcoming 5y ago
You've show a syntactic difference, not a functional difference. What does the 'ref' keyword change about how C# passes the argument to the function? I'd imagine (having zero C# experience) that it passes either a pointer, or an index, or an offset, to the function by value. It may also just copy the argument, pass it to the function, and then copy the copy back to the original argument (which would be daft).
- MaxBarraclough 5y ago
  > You've show a syntactic difference, not a functional difference. Kinda, but that difference is important. We can say that C allows us to simulate pass-by-reference by using pointers. It's still true that the C language does not support pass-by-reference semantics. Taking the address of a variable is an operation that the C language permits us to do, yielding a new value (a pointer value). This isn't part of C's argument-passing functionality, though. > What does the 'ref' keyword change about how C# passes the argument to the function? The internals of C# compilers aren't really the point, but I believe .Net does it the copy-intensive way, copying to pass in and copying again to pass the new value back out. I don't think this a real performance problem though, unless you overuse the feature.