# RefStruct.size

Get the size (number of properties) of the current state of a RefStruct.

## Signatures

```ts
export declare const size: <S extends object, E, R>(ref: RefStruct<S, E, R>) => RefSubject.Computed<number, E, R>;
```

## Why

Makes size a live projection of the struct; consumers can sample it now or observe it without
copying the source state.

## Ownership and lifetime

The size view retains no independent state. An Effect read samples the source once; Fx
observation follows later pushes and its observing Scope owns subscription cleanup.