Python Programming Overview 2

Python Programming Overview 2

(1) Indentation

Python & Whitespace

• Whitespace is significant in Python (sorf of)
  • Text editor: vim, notepad++
• Makes for significantly more readable code
• Whitespace is only “significant” at the very left of your statements, to denote blocks

Code Blocks

• Indenting denotes the beginning of a block; “outdenting” or “dedenting” denotes the end of the block
• Blocks include: classes, functions, if statements, loops, other control structures

Everything Else

• In other part of the code, whitespace is actually not significant, and you are free to use it how you like
• Examples include arbitrary newlines, implicit or explicit continuation lines

Exercises

• Run the Python interpreter
• Define a function with an arbitrary name and no arguments
• Press enter, then type print ‘hi!’ and press Enter
• Repeat the above two steps, but press the tab key before you type the print statement

(2) Spaces Over Tabs

A Warning

• Stick to one or the other (Don’t mix them!)
  • Even if you are writing C, it’s not safe to mix spaces and tabs in your source code
  • Beware the war of tabs vs. spaces

The Case for Spaces

• PEP 8 identifies spaces as preferred over tabs
  • PEP 8 is a style guideline for Python
• Besides that, there is no real requirement (only that you do not mix the two)
• Code or text editors can be configured to insert 4 (or any number of) spaces in place of a tab

Editor Suggestions

• A few suggestions for editors that have the ability to convert tabs to spaces
  • Vim, Emacs, Nano, gEdit, Sublime Text (full version not free)