How Do Imports Impact Your Go Program?

Understanding the Concept of Import Side Effects in Go

In Go, the use of imports can have side effects, a concept that has been highlighted in Effective Go. Side effects essentially refer to code or features that are executed during the import process, resulting in a modified state of the system.

To elaborate, certain packages, such as those for databases or image formats, can contain initialization or setup code. When these packages are imported, this initialization code is executed. For instance, importing the "image/png" package registers handlers, sets up configuration files, or modifies resources on disk.

Unlike constants or variables defined at the package scope, which don't typically have side effects, code within an init() function can have a significant impact. This is because init() is called after all variable declarations have evaluated their initializers. As a result, code within init() can execute and potentially modify the state of the system.

It's important to be aware of these side effects and use imports judiciously. In some cases, a blank import (import _ "package_name") can be employed to access package initialization without actually using the package itself, thereby avoiding side effects.

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