Python Pocket Reference

Statements and Syntax

Syntax Rules

Rules for writing Python programs.

Control flow

Statements execute one after another, unless control-flow statements are used (if, while, for, raise, calls, . . . ).

Blocks

Blocks are delimited by indenting all their statements the same amount with spaces or tabs. A tab counts for enough spaces to move the column to a multiple of 8.

Statements

Statements end at the end of a line but may continue over multiple lines if the prior line ends with a \, or an open ( ), [ ], or {} pair, or an open triple-quoted string. Separate statements with a semicolon (;) if more than one on a line.

Comments

Comments start with a # (not in a string constant) and span to the end of the line.

Documentation strings

If a function, module file, or class begins with a string constant, it’s stored in the object’s __doc__ attribute.

Name Rules

Rules for user-defined names in programs.

Format

User-defined names start with a letter or ‘_’, followed by any number of letters, digits, or ‘_’s.

Reserved words

User-defined names cannot be the same as any Python reserved word (listed in Table 1-11).

Case sensitivity

User-defined names and reserved words are always case- sensitive: SPAM and spam are different.

Unused tokens

Python does not use characters @, $, or ?, though they may appear in string constants.

Creation

User-defined names are created when assigned, but must exist when referenced.

Table 1-11. Reserved Words

and	assert	break	class
continue	def	del	elif
else	except	exec	finally
for	from	global	if
import	in	is