Bash script; how to use vars and funcs defined after command

Question

How to use variables or functions that are defined after the command.

Variable

#!/bin/bash

echo Hello \"$who\"
who=\"World\"

Answer 1

Variables and functions always have to be defined before use. This is because function definitions are actually commands that assign the name in the current context, and not like in C where they merely provide an implementation for a name.

You can instead use control flow to ensure that the definitions execute before your code, regardless of their relative layout in the file:

main() {
  echo "Hello $var"
}

var="world"
main