Django Web Development Guide

2015-7-14 20:43:44

P14: ' Raw ' designator tells the interpreter not to convert any special characters in the string ... For example: filename = R ' C:\temp\newfolder\robots.txt '. To maintain consistency, the raw string is usually used regardless of whether a regular expression uses a backslash.

P18:dict.get (' key ' [, ' does not exist this key ']) is more secure than using dict[' key ' directly, because the Get method always returns a value (the default is None). You can also use the setdefault (' key ', ' value ') method, which acts like get, and if the key does not exist, it will automatically create a key-value pair using the default value, so that the subsequent call to the key will not produce an error.

P23: Common python Exceptions:

　　Assertionerror assert (assertion) statement failed

　　Arrtibuteerror attempts to access properties that an object does not have, such as foo.x, but Foo has no attribute x

　　IOError Input/Output exception, basically cannot open file

　　Importerror cannot introduce modules or packages; it's basically a path problem.

　　indentationerror syntax error; code not aligned correctly

　　indexerror Subscript index is out of sequence boundary, for example, when X has only three elements, but tries to access X[5]

　　Keyerror attempts to access keys that do not exist in the dictionary

　　Keyboardinterrupt CTRL + C key is pressed

　　nameerror Using a variable that has not been assigned to an object

　　SyntaxError Python code is illegal, code cannot mutate

　　TypeError The Incoming object type does not match the requirements

　　Unboundlocalerror attempts to access a local variable that is not set, basically because another global variable with the same name causes you to think that you are accessing it

　　ValueError Pass in a value that is not expected by the caller, even if the value is of the correct type

P24:httplib module no longer exists ...

　　

Django Web Development Guide