How to use functions and variables of another shell script ?

Suppose we have two shell scripts
1. script-1.sh
2. script-2.sh

Suppose script-2.sh contains a function called someFunction(). Script-1.sh can not call the function someFunction(). To able to call the function you have to add the following line in script-1.sh .

source script-2.sh

Now, script-1.sh will be able to call all the functions and variables inside script-2.sh