GIII

Appendix C

Reserved Words and Identifiers in Python


Reserved Words

Python won't allow you to use any of its reserved words as variable or function names.  Here's the full list, with a very brief explanation.
and
Logical and
assert
Assert that some condition exists or is true
break
Break out of a while or for loop
class
Begin a class definition
continue
Immediately go to top of while or for loop
def
Begin a function definition
del
Delete (destroy) following object
elif
If clause
else
If clause
except
Execute following statements if try failed
exec
Run Python code
finally
Execute following statements if try succeeded
for
Begin a for loop
from
Begin a qualified import statement
global
Look in global namespace for following variable names
if
If clause
import
Find, read and execute a module
in
Membership in sequence
is
Identity query
lambda
Begin unnamed function definition
not
Logical not
or
Logical or
pass
Do nothing
print
Output
raise
Notify of exceptional condition
return
Exit function
try
Try the following statements and see if they work
while
Begin while loop

Reserved Identifiers

Certain classes of identifiers (variable or function names) have special meanings. These are:
_
This variable is used in the interactive interpreter mode only. When it exists, it stores the result of the last evaluation; the variable lives in the __builtin__ module. If it does not exist, it has no special meaning and is not defined.  Leave this one to Python.
_*
Any variable beginning with an underscore is not imported by from module import *.  It's OK to create your own variables that begin with one underscore, but you can only use it in the module where you created it.
__*__
Any name beginning and ending with two underscores is defined by Python; includes __main__, __import__, __add__, etc.  You can implement some of the functions yourself (Appendix D), but never create variables with a name like this.
__*
Used in class-private name mangling; you won't really need this, as it's a fairly advanced concept, but you can find out more about it at http://www.python.org/.

Builtin Names

The __builtin__ module contains a minimum set of function names that you should never try to use, either as function names or variable names. You can redefine them, but you won't like the results.  Here's the full list.  Find out more at the usual place, http://www.python.org/.

__import__()
abs()
apply()
buffer()
callable()
chr()
cmp()
coerce()
compile()
complex()
delattr()
dir()
divmod()
eval()
execfile()
filter()
float()
getattr()
globals()
hasattr()
hash()
hex()
id()
intern()
int()
isinstance()
issubclass()
len()
list()
locals()
long()
map()
max()
min()
oct()
open()
ord()
pow()
range()
raw_input()
reduce()
reload()
repr()
round()
setattr()
slice()
str()
tuple()
type()
vars()
xrange()

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