Python 5th Day

Further understanding of adorners

If you have the following logic:

def connect_db ():     Print ' Connect DB ' def close_db ():     Print ' Close DB ' def Query_user ():    connect_db ()    print'Query the user'      close_db ()

If we encapsulate the specific logic of query_user as a new function and then pass the new function into the query_data, then we need a different query method later, then we can encapsulate the new function.

def Query_user ():     Print ' query Some user ' def query_data (query):    connect_db ()    query ()    close_db ()

Well, Query_data is Query_user's decoration. But if we want to keep query_user, we need to call Query_data and return a function.

defQuery_user ():Print 'query Some user'defquery_data (query):"""define the adorner, return a function, wrapper the query with a wrapper"""    defwrapper (): connect_db () query () close_db ()returnwrapper#here call Query_data for actual decoration (note that decoration is a verb)Query_user =Query_data (Query_user)#call the decorated function Query_userQuery_user ()

The above is a complete adorner, the key point is that when calling Query_data, a wrapper function is returned, and this wrapper function performs some logic before and after the query function.

Note Query_user = Query_data (query_user) equals

# decorate with the @ call adorner @query_data def Query_user ():     Print ' query Some user '

@ Calling the adorner's syntax is not necessary, but just a syntactic sugar.

Multilayer Decorators

defDecorator1 (func):Print 'Inside Decorator1'    returnfuncdefDecorator2 (func):Print 'Inside Decorator2'    returnFunc@decorator1@decorator2defFunc1 (A, B, c):returnA, B, CPrintFunc1 (' All','Base','US')

In the above example, func1 is decorated with two decorators, so the decorator1 is decorated with a new function that is decorator2 decorated, so the output should be

Inside decorator2inside decorator1 ('all'base' ' US ')

Equivalent to:

func1 = Decorator1 (Decorator2 (FUNC1))

Module

• Configparser
  • More details, see:https://docs.python.org/3/library/configparser.html
  • The Configparser class implements a basic configuration language which provides a structure similar to what's found in Mic Rosoft Windows INI files.
    • INI File Structure:
      2. A configuration file consists of sections, each led by a [section] header
      4. By default, section names is case sensitive but keys is not
      6. For example:

      7. [Simple Values]Key=valuespaces in Keys=allowedspaces in Values=allowed as wellspaces around the delimiter=Obviouslyyou can also use:to delimit keys from values[All Values is Strings]values like this:1000000or this:3.14159265359is they treated as numbers?: Nointegers,Floats and Booleans is held As:stringscan use the API to get converted values Directly:true[Multiline Values]chorus:i ' m A lumberjack,and i ' m okay I sleep all night and I work all day[No Values]Key_without_valueempty String Value here=[can use comments]# like this;or this# By default @ an empty line.# Inline comments can is harmful because they prevent users# from using the delimit ing characters as parts of values.# that being said,This can is customized. [Sections Can Indented]Can_values_be_as_well=True does_that_mean_anything_special=False Purpose=formatting for readability multiline_values=Is handled just fine as long as they is indented deeper than the first line of a value # did I mention we can indent comments, too?

  • How to Read, Update and Delete Options

  • ImportConfigparserImportOSdefcreate_config (path):"""Create a config file"""Config=Configparser.configparser () config.add_section ("Settings") Config.set ("Settings","Font","Courier") Config.set ("Settings","font_size","Ten") Config.set ("Settings","Font_style","Normal") Config.set ("Settings","Font_info",               "You is using% (font) s at% (font_size) s PT") with open (path,"WB") as Config_file:config.write (Config_file)defget_config (path):"""Returns the Config object"""    if  notos.path.exists (path): create_config (path) config=Configparser.configparser () config.read (path)returnConfigdefget_setting (path, section, setting):"""Print out a setting"""Config=get_config (path) value=config.get (section, setting)Print "{section} {setting} is {value}". Format ( section=section, Setting=setting, value=value)returnvaluedefupdate_setting (path, section, setting, value):"""Update a Setting"""Config=get_config (path) config.set (section, setting, value) with open (path,"WB") as Config_file:config.write (Config_file)defdelete_setting (path, section, setting):"""Delete a Setting"""Config=get_config (path) config.remove_option (section, setting) with open (path,"WB") as Config_file:config.write (Config_file)#----------------------------------------------------------------------if __name__=="__main__": Path="Settings.ini"Font= get_setting (Path,'Settings','Font') Font_size= get_setting (Path,'Settings','font_size') update_setting (Path,"Settings","font_size"," A") delete_setting (Path,"Settings","Font_style")

String formatting

In Python, the format used is consistent with the C language, implemented in%,

Common placeholders are:

%d: integer

%f: Floating point

%s: string

where formatted integers and floating-point numbers can also specify whether to complement 0 and the number of digits of integers and decimals:

' %2d-%02d ' % (3, 1)'  3-01'%.2f' % 3.1415926'  3.14'

To pass in as a dictionary:

% (name) s,% (age) d%{'name'"Gary" Age ': 30}

Once a placeholder is present and you want to pass in%, you need to use a percent, which is equivalent to escaping

　　　　　　　　　　　　　　

Python 5th Day