How can a variable with limited scope be declared inside a class or module?

In Go, the scope of a variable is determined by its name and the place of declaration. To declare a variable with limited scope inside a class (structure) or module (package), the following approaches are used:

• Inside a function or method: the variable is declared using var or short declaration := and is visible only within that function or method.

• Inside a package: variables, functions, and types with names starting with a lowercase letter are visible only within the package (module). If the name starts with an uppercase letter — it is exported and accessible from other packages.

Example:

package mypackage

var packageVar = 10 // visible only within the mypackage package

func myFunc() {
    var localVar = 5 // visible only inside myFunc
    _ = localVar
}

// Exported variable
var ExportedVar = 20 // accessible from other packages

Thus, to limit the scope of a variable within a module, you should use names starting with a lowercase letter and declare variables outside functions but within the package. To restrict visibility inside a class (structure), usually, fields of the structure are used, where visibility is also determined by the case of the first letter.