How Can You Achieve Generic Programming for Variadic Functions in Go Without Templates or Overloaded Functions?

Generic Variadic Arguments in Go

Despite Go's lack of templates and overloaded functions, achieving some form of generic programming for variadic functions is possible.

Redundant Function Code Issue

As illustrated in the provided code snippets, many functions share similar logic but handle different types. This repetition can lead to redundant code.

Solution: Interface{} Type

One approach to reducing redundancy is to utilize Go's interface{} type, a special type compatible with all types. By modifying the functions to accept and return interface{} values, common logic can be centralized.

<code class="go">func (this Document) Get(name string, defaults ...interface{}) interface{} {
    v, ok := this.GetValueFromDb(name)
    if !ok {
        if len(defaults) >= 1 {
            return defaults[0]
        } else {
            return 0
        }
    }
    return v
}</code>

Client Code

In client code, the Get function can be used to retrieve values of specific types:

<code class="go">value := document.Get("index", 1).(int) // Panics if the value is not an int</code>

or handle type checking explicitly:

<code class="go">value, ok := document.Get("index", 1).(int) // ok is false if the value is not an int</code>

Drawbacks and Alternative

While the interface{} approach reduces code redundancy, it introduces runtime overhead. A better solution may involve refactoring the code to eliminate the need for repetitive logic.

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