Function calc

calc(props?: MetaData): (ownerCls: any, fldName: string) => void
following member is a calculated field
Parameters
- Optionalprops: MetaData
Returns (ownerCls: any, fldName: string) => void
Example
```
@data_calc( )
get my_field(): string => {
	return 'hello';
};
```
- Defined in src/core/core_data.ts:213