DEV Community

Discussion on: Why use pointers at all.

pentacular profile image
pentacular

Passing an int * in C does not pass an int.

Thread Thread
jessekphillips profile image
Jesse Phillips • Edited on

Right you're passing a reference to int.

Thread Thread
pentacular profile image
pentacular

No, you're passing the value of an int *.

Thread Thread
jessekphillips profile image
Jesse Phillips

You're spending so much effort being right rather than communicate.

You're trying to prove that this scotsman is not a true scotsman. And fail to recognize that he is in fact a scotsman.

Rather than directly addressing the definition of reference. You run me in circles. First by saying I needed to use the words of the spec, then by saying those words aren't the same in this other spec.

I pull in a third-party which you completely ignore, probably because it doesn't match your true scotsman. You try to show me differences, even though I clearly demonstrated an understanding of the different semantics.

You can only accept being right and have no interest in communicating.


Had you accepted the words used in the Java spec I could have answered No to the question about the behavior of C.

C did use the word reference, but it was not trying to define a language construct, instead it was using the word to help explain the semantics of a pointer, this matches the definition provided by Wikipedia.

Java on the other hand is defining a language construct. It has different semantics then C++'s use with the same name.

So we have reference as a concept, reference as a language construct in Java, and reference as a language construct in C++. Thus in order to communicate we have to agree to which of these we mean.

I thought that you would use the one defined in the language spec since that is what requested at the start. When I realized you were not sticking to that requirement, I was able to pull in more language into the mix and see how you would contort your logic to make it seem that all of these uses are consistent (they are not). But I was sadly disappointed when you wouldn't even touch Wikipedia definition.

Thread Thread
pentacular profile image
pentacular

Since we are talking about pass-by-reference, it is the semantics of pass-by-reference that are significant.

If your definition of 'reference' is 'something that can be used to find something', then there will be nothing that is not a reference.

Have a string? I can use that to reference something .: strings are references!

Have an integer? I can use that to reference something .: integers are references!

Have anything? I can use that to reference something .: anything is a reference.

Which is the path down which you are going by claiming that pointers are references, because they can reference things, and therefore passing a pointer to something is passing that something by reference.

It's meaningless -- which is why I have kept bringing it back to the semantics required by pass-by-reference.

Thread Thread
jessekphillips profile image
Jesse Phillips

And why I started with your ask, to use the Java spec which does not define them as you have here. My point was that we never established an agreed and consistent definition for reference.

I never once saw you pull out a definition from your sources. Even definition I had to dig for and you would deflect because it wasn't the one you wanted.

Thread Thread
pentacular profile image
pentacular

And I talked about the Java spec, which defines "references values" (abbreviated sometimes to references).

These are not references in the sense of pass-by-value, as I've demonstrated many times above.

You might claim that they're references in the sense that anything can be used to refer to something else.

But that won't get you references with the semantics required by pass-by-reference, which means that you can't claim that passing one is pass-by-reference.

Let's just imagine that they were called "oranges" -- would you be claiming that passing an "orange" gave you pass-by-reference?

If not, then it's clear that this is simply due to being confused by a name choice.

Thread Thread
jessekphillips profile image
Jesse Phillips • Edited on

Let's try it.

"reference values (often just oranges)"

"All interactions with objects and array is by oranges, much like pointers in C."

Yep, I'd use it.

"Objects are pass by oranges and if C had them, it too would be pass by oranges."

Thread Thread
pentacular profile image
pentacular

Ok, and does pass-by-orange have pass-by-reference semantics, or does it have pass-by-value semantics? :)

Thread Thread
jessekphillips profile image
Jesse Phillips • Edited on

Have we defined what we are discussing as passed and the definition of reference yet?

Thread Thread
pentacular profile image
pentacular

I've done so several times.

Here is the simplest requirement, again.

When passing by reference, modifying the parameter modifies the argument.

void foo(int &a) {
  a = 2;
}

int main() {
  int i = 1;
  foo(i);
  cout << i << endl;
  // Outputs 2.
}
Enter fullscreen mode Exit fullscreen mode
Thread Thread
jessekphillips profile image
Jesse Phillips

Under that definition, no passing by oranges does not have the same semantics as pass by reference.

This however changes the subject to the parameters of the functions. I have been talking about the object for which the parameter refers. Could we stick with talking about the concept I'm actually trying to get across rather than introducing a introducing a different one.

Since pass by oranges is not a term used in the Java spec, could you describe the pass by oranges semantics using spec terms?