Hands-On Dependency Injection in Go

Applying method injection to the exchange package

The exchange package is responsible for loading the current currency exchange rate (for example, Malaysian Ringgit to Australian Dollars) from an upstream service. Similar to the data package, it provides simplified and abstracted access to this data.

The following are the relevant parts of the current code:

// Converter will convert the base price to the currency suppliedtype Converter struct{}// Do will perform the loadfunc (c *Converter) Do(basePrice float64, currency string) (float64, error) {   // load rate from the external API   response, err := c.loadRateFromServer(currency)   if err != nil {      return defaultPrice, err   }   // extract rate from response   rate, err := c.extractRate(response,