What Does the '.' Mean in Go's Import Statements?

Understanding the Dot ('.') in Go Import Statements

In Go, packages are typically imported using path aliases or explicit identifiers. However, there's a special case where a period ('.') is used in import statements.

Consider the following example:

import (
    "http"
    . "launchpad.net/gocheck"
    "launchpad.net/lpad"
    "os"    
)

Here, the use of '.' in the "launchpad.net/gocheck" import statement has a specific significance.

Significance of the Dot ('.')

The period ('.') in an import statement instructs the compiler to alias all exported identifiers from the imported package to the current file block. This means that these identifiers can be used without prefixes, as if they were declared in the local file.

For example, with the '.' import, "gocheck" identifiers such as Assert and Error() can be used directly without prepending "gocheck.":

func ExampleSuite() {
    Assert(/* ... */)
    Error(/* ... */)
}

Advantages

Using '.' in import statements can simplify and shorten code, especially for packages that expose a large number of exported identifiers. It eliminates the need for explicit prefixes, reducing the verbosity of code.

Reference

The official Go documentation provides details on import declarations: http://golang.org/doc/go_spec.html#Import_declarations

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