When Should You Use Blank Identifiers for Importing Packages in Go?

Importing with Blank Identifier in Go: A Practical Application

The Go programming language allows for importing packages solely for their side effects, such as initialization. This is achieved by assigning a blank identifier as the package name. While the general concept is understood, specific real-world examples of this practice can be elusive.

One such use case is the initialization of external resources. For instance, a package may need to register a database driver with the standard library's database/sql package. This can be done through the package's init function:

package mydatabase

func init() {
    sql.Register("mydriver", &MyDriver{})
}

By importing the mydatabase package with a blank identifier in the main program, the init function will be executed, but the package's exported functions will not be used:

import _ "mydatabase"

func main() {
    // ...
}

Another scenario is configuring logging. A package may provide a default logging configuration in its init function, which can be imported into the main program without explicitly using any of its functions:

package mylogging

func init() {
    log.SetFlags(log.Lshortfile | log.LstdFlags)
}

In the main program:

import _ "mylogging"

func main() {
    // ...
    log.Println("Application started")
}

By utilizing the blank identifier, we can avoid the need to declare unnecessary and unused variables in the main program, making the code cleaner and more maintainable.

These examples illustrate the practical application of importing with a blank identifier in Go, allowing for side-effect initialization of external resources and configuration of global settings.

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