Hands-On Software Engineering with Golang

Defining the Aggregator interface

The Aggregator interface describes the set of methods that must be implemented by Go types so that they can be used with our graph processing framework for data aggregation purposes:

type Aggregator interface {
    // Type returns the type of this aggregator.
    Type() string

    // Set the aggregator to the specified value.
    Set(val interface{})

    // Get the current aggregator value.
    Get() interface{}

    // Aggregate updates the aggregator's value based on the provided     // value.
    Aggregate(val interface{})

    // Delta returns the change in the aggregator's value since the last     // call to Delta. 
    Delta() interface{}
}

One of my pet peeves is that the methods in the preceding interface definition use interface{} values. Unfortunately, ...