• Python code can be written in two different “containers”:
  • Interactive interpreter (not permanent)
  • Modules or programs (permanent)

• The content of a module can be used in a script (or in a different module) by importing the module

• Scripts, programs, modules can be written in text files.

• Inside modules you can define other containers: classes and functions.

• More in general, modules are containers for data, functions and classes.

• In other words, we will call modules text files containing definitions of data (through variable’s assignment), functions and classes.

• We will call programs or scripts text files containing definitions AND actions.

• You will run programs and import modules.

• When you import a module, Python reads and executes each line contained therein.

• It is good practice to write small re-usable pieces of code in separate modules and connect them through the import statement and the dot syntaxt.

• The objects contained in modules (and, if you want to, in classes and functions) are: data structures; variable definitions; operators; control flow statements.

The “dot” syntax

The matryoshka doll-like structure of Python

module.class.method()

module.method()

class.method()

module.variable

module.class.variable

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Challenge

• Open a text file using gedit
• Write:print "My name is:", "myname"

• Save the file in your home directory with the name: my_name.py
• Go to your home directory using the command-line interface
• Type at the prompt: python my_name.py
• Open a DIFFERENT text file using gedit
• Write: import my_name

• Save the file in your home directory with the name: my_first_run.py
• Go to your home directory using the command-line interface
• Type: python my_first_run.py

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