An example of using modules and packages in python

modules_and_packages.py

### BASIC SETUP
# set pleasant tab stops
cat <<EOF >~/.nanorc
set tabsize 4
set tabstospaces  
EOF

# dir for all python command line programs
mkdir ~/programs

cd ~/programs


### CREATE A PYTHON MODULE 
# create a file mymaths.py
def fib(n):
    if n==0:
        return 0
    elif n==1:
        return 1
    else:
        return fib(n-1) + fib(n-2)
        
def main():
    for i in range(0, 20):
        print(fib(i))

if __name__ == "__main__":
    main()

# note it will run standalone
python mymaths.py

### USING THE MODULE
# create a file main.py
import mymaths

for i in range(0, 20):
    print(mymaths.fib(i))

# run main.py
python main.py

### CONVERT TO A PACKAGE
mkdir myutils
mv mymaths.py myutils
cd myutils
touch __init__.py
cd ..

# edit main.py to reference package
import myutils.mymaths

for i in range(0, 20):
    print(myutils.mymaths.fib(i))

## create a file myutils/myconv.py
def inches_to_mm(length):
	return length * 25.4

## edit main.py to reference package
import myutils.mymaths
import myutils.myconv

for i in range(0, 20):
    print(myutils.mymaths.fib(i))

print("12 inches in mm:")
print(myutils.myconv.inches_to_mm(12))

python main.py