> If the underlying API changes the argument type, consumers will have an issue > regardless. For those cases where the expression is simply `default`, you'd > actually be protected from the API change, which is a net benefit already. > > This also protects the user from changes in the argument names.
As I said, I don't have a particular problem with default as a keyword to express "whatever the default value might be in the function declaration", but I do have some real concerns about its use as an operand in an expression. The RFC provides for a single valid use case of operators (i.e. things like default | JSON_PRETTY_PRINT ), yet calls for a huge array of valid operations, many of which the RFC itself notes don't make much / any sense. I'd personally like to see this RFC dramatically reduce the scope of operations supported with default as an operand initially (e.g. perhaps only bitwise ops), and revisit additional operations as needed down the road. IMO there is a very small subset of all PHP operators that make any sense at all in this context, and even fewer that I think are a good idea to allow even if they might make some sort of sense.
