Bioinformatics Programming Using Python

Appendix A. Python Language Summary

This appendix summarizes the Python language as used in this book. Some of its more obscure features have been omitted.

Language Components

Special Syntactic Elements

#

Begins a comment; the rest of the line is ignored

\

At end of line, indicates that line break should be ignored

'' or ""

Enclose a one-line string

''' ''' or """ """

Enclose a multiline string

()

Enclose an expression or call a function

Keywords

Table A-1 shows the complete list of Python’s keywords. Note that a few of them play multiple roles:

• not is a logical operator and part of the not in and is not operators.

• in is an operator as well as part of a for statement.

• as names things in both with statements and except clauses.

Table A-1. Keywords

Kind	Keywords	Note
Value names	None True False
Operators	not or and in is del	It is the words that are keywords: not is both a Boolean operator and part of the not in and is not operators
General	pass assert return yield
Definitions	def class as import from
	global nonlocal lambda	These two keywords affect the scope of assigned names; they are not used in any of the book’s code examples.
Conditionals	if else elif
Loops and iterations	while for break continue	Also in, included with the operators, as part of a for statement
Exception handling	try except finally with raise	with is included here because it creates an implicit try/finally exception handler

Special Names

In addition to keywords, the names described in Table A-2 have special significance. An asterisk stands for any ...