Optional parameters, default parameter values and method overloading

By design, Go does not support

• optional parameters,
• default parameter values,
• or method overloading.

Method dispatch is simplified if it doesn’t need to do type matching as well. Experience with other languages told us that having a variety of methods with the same name but different signatures was occasionally useful but that it could also be confusing and fragile in practice. Matching only by name and requiring consistency in the types was a major simplifying decision in Go’s type system. Go FAQ: Why does Go not support overloading of methods and operators?

However, there are

• variadic functions (functions that accept a variable number of arguments),
• and dynamic method dispatch is supported through interfaces.

For more on this, see Interfaces in 5 easy steps.

The idiomatic way to emulate optional parameters and method overloading in Go is to write several methods with different names. For example, the sort package has five different functions for sorting a slice:

• the generic sort.Slice and sort.SliceStable,
• and the three more specific sort.Float64s, sort.Ints, and sort.Strings.

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