Kumpulan Kesalahan dan Union !T

In Zig there are no exceptions. An error is just an ordinary value your function can return, so failure is visible in the code.

An error set is a named group of possible errors. You list the variants much like an enum of things that can go wrong.

Each member of an error set is reached with a dot. The value FileError.NotFound is a single concrete error you can return.

You do not always need a name. Writing error{Empty} inline creates a tiny one-off error set right where it is used.

The ! in a type builds an error union. The type before it is the success value; an error may appear in its place instead.

You can read !u32 as either a u32 or an error. The single value carries both outcomes, so callers must pick one.

An error union has exactly two shapes at runtime: a valid payload of type T, or one of the errors from the set. Never both.

Put the error set on the left of ! to say exactly which errors are allowed. This documents failure right in the type.

The || operator on two error sets combines them into one. This lets a function admit errors from several sources at once.

The built-in anyerror contains every possible error. It is convenient but loses the precision of a named set, so use it sparingly.

Because errors live in the type, the compiler knows every failure a function can produce. Nothing slips past you unhandled.

You see the type FileError!u32 on a function. What does it describe?

You met error sets, the !T union, set merging with ||, and anyerror. Errors are plain values the type system tracks for you. ✅