Packages

Go programs are organized in packages.

• Package names must be lowercase. You may not include underscores or mixedCaps.
• You may only have one package per directory.
• Packages do not have to match the name of their directory, but it is convention to do so.
• Functions and variables that are uppercase in a package can be accessed directly by a consumer (i.e. they are "public"). These types are referred to as exported. Functions and variables that are lowercase in a package cannot be accessed outside of a package (i.e. they are "private").
• Exported functions and variables should always have a comment block that explains their purposed and function. Most syntax checkers will flag exported arguments that do not have a comments block.
• Packages are imported by directory path, but used by package name. For instance, if I have a package named coolpkg in the github.com/crossplane-book/crossplane-book/pkg/consumed directory, the import will look as follows:

package consumer

import "github.com/crossplane-book/crossplane-book/pkg/consumed" // imported by directory

func myFunc() {
    coolpkg.DoThing() // use by package name [note: public DoThing()]
}

• You can alias a package import. This is especially useful when you import two packages of the same name:

package consumer

import (
  onetype "github.com/crossplane-book/crossplane-book/pkg/one/type"
  twotype "github.com/crossplane-book/crossplane-book/pkg/two/type"
)

func myFunc() {
    onetype.GetAPIVersion()
    twotype.GetAPIVersion()
}

For additional information, checkout the Go Package Style Guide.