Why Do My Go Struct Field Values Revert After Modification?

Go Struct Field Reverting Conundrum: Delving into Pointers and Receivers

In Go, developers often encounter the peculiar situation where a field value within a struct mysteriously reverts to its original state after being modified. This issue stems from the concept of passing values by copy, rather than by reference.

Consider the example provided:

func (this MockConnector) sendCommand(payload map[string]string)

Here, the sendCommand method in the MockConnector struct accepts a payload as a value. When the method modifies this payload, it is only affecting a copy, not the original struct's field.

To resolve this, Go requires the use of pointers to structures that need to be modified. By modifying the method signature to:

func (this *MockConnector) sendCommand(payload map[string]string)

we are now passing a pointer to the struct, allowing us to directly modify the intended field.

Additionally, in Go, it is discouraged to use this as a receiver name. Instead, it is considered best practice for all methods in a specific type to utilize pointer receivers. This ensures a consistent interface regardless of whether the value is a pointer or not.

By embracing these principles, developers can effectively overcome the "field reverting" issue, ensuring that their struct fields accurately reflect the intended modifications.

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