You're not mentioning or alluding to the one obvious syntax error. I don't know how to spoiler it so I will say there is an issue on the second line that, again repeating, I don't know how to call out.
And yes, I work in multiple languages.
And yes, I work in multiple languages.
Performance issues, on the other hand, I can see accidentally arising.
Where you want to make sure a pointer you've been given isn't null before you try to dereference it. Without short-circuit, this becomes a segfault.
I've never seen someone use an "or" pattern in a non-confusing way.
That is, I've seen "and" patterns that act as a safety/early out. I fail to see the use of an "or" pattern where you want to stop executing if the first value is true (ignoring using nots to invert the logic of an and pattern, and I would criticize that).
They do exist in other languages. ES has it in exactly that form. Java has it in the |= form, not to be confused with the bitwise OR of the same form.
Whether or not these short-circuit is not all that interesting for most boolean logic. (Though it can be useful to know if these are used as hacky error-handling and default-setting. It depends on how you read "something" whether or not that's going on here.)
Where and when? Because I was the only person alluding to it, and the replies to my post.
> Whether or not C++ has them (it doesn't) is exactly the point of that code snippet.
C++ has boolean assignment operators that operate the way that the code is clearly meant to operate. That code does not have have a valid one. Where do you think Java got them from?
https://www.w3schools.com/cpp/trycpp.asp?filename=demo_oper_...
||= will not assign anything unless the LHS variable is falsy. It will not even evaluate the right side unless LHS is falsy.
|= will work the same in C++ and ES mostly (depending on types)
The fact that the ||= operator short circuits makes sense from an optimization point of view. I will maintain that there is no good use for the correctness (as opposed to optimization) of the code to depend on that feature.
The words "boolean assignment operator" are in the first sentence after the code snippet in megous' post.
> C++ has boolean assignment operators that operate the way that the code is clearly meant to operate. That code does not have have a valid one. Where do you think Java got them from?
As far as I can tell the |= operator in C++ is the same as in C, i.e. a bitwise OR operator. It works for booleans due to their bit pattern, but it's not the same. My C++ knowledge is extremely limited, so I looked it up and I may be misinformed though.
Java's |= is different for ints and boolean. There are no bitwise operators for booleans: bool1 | bool2 is a strict logical operation (that doesn't short-circuit). bool1 |= bool2 is a logical operation that will fail when other types are mixed in. int1 |= int2 is a bitwise operation. Java does not have a short-circuiting ||= operation (but ES does).
For the most part these differences aren't that important, but they do trip people up when switching between languages.
This is true.
> It works for booleans due to their bit pattern, but it's not the same.
This makes less sense. A bool in c++ is just an integer value with few inputs. It is, as far as I can tell, the exact same.
> Java's |= is different for ints and boolean.
Java has bool and int as different types. There were versions of C++ compilers that just straight out had bool as a typedef of int.