init()

The init() function in go is a function that is initialized first in the package. The order of evaluation is

1. Constants and variables
2. Dependency init()s in alphabetical order
3. Main package init()
4. main()

Problems

Error management in init() functions is limited since they do not return errors. The only way to indicate that something has gone wrong in an init() is to panic. This behavior should not be left to the package to decide whether to stop an application or not.

Testing also becomes a problem with init() functions. This function will always be executed before running test cases which can create complications.

Global variables are also required when init() functions are used for initialization. These introduce a lot of additional downsides as they can be modified by an function in the package and make it difficult to isolate test cases.