function alias, usually C library function
lambda that takes return value of Func and returns true itself if result is considered successful
file where the expr is evaluated
line where the expr is evaluated
proxy Caller value with a single call method which accepts same arguments as Func and throws this exception if verify(Func(args)) evaluates to false.
Calls Func automatically checking errno and storing name
If verify returns false when called with return value of Func, global errno gets checked and this ErrnoException instance gets thrown with message set from that errno and caller name set to Func identifier.
Presence of additional wrapper struct is dictated by limitations of dmd1 type inference in method/function signatures.