### Gettable socket option requirements

In the table below, `X` denotes a socket option class, `a` denotes a value of `X`, `p` denotes a value that meets the protocol requirements, and `u` denotes an identifier.

Table 9. GettableSocketOption requirements

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).
`a.data(p);` | a pointer, convertible to `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.
`a.resize(p, s);` |  | post: `a.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 `a` does not support the specified size.