A type X meets the GettableSocketOption requirements if it satisfies the requirements listed below.
In the table below, a denotes a (possibly const) value of type X, b denotes a value of type X, p denotes a value of a (possibly const) type that meets the Protocol ([socket.reqmts.protocol]) requirements, and s denotes a value of a (possibly const) type that is convertible to size_t and denotes a size in bytes.
| expression | type | assertion/note pre/post-conditions |
| a.level(p) | int | Returns a value suitable for passing as the level argument to POSIX getsockopt (or equivalent). |
| a.name(p) | int | Returns a value suitable for passing as the option_name argument to POSIX getsockopt (or equivalent). |
| b.data(p) | void* | Returns a pointer suitable for passing as the option_value argument to POSIX getsockopt (or equivalent). |
| a.size(p) | size_t | Returns a value suitable for passing as the option_len argument to POSIX getsockopt (or equivalent), after appropriate integer conversion has been performed. |
| b.resize(p,s) | post: b.size(p) == s. Passed the value contained in the option_len argument to POSIX getsockopt (or equivalent) after successful completion of the function. Permitted to throw an exception if the socket option object b does not support the specified size. |