Custom Actions for argparse Documentation

Size: px

Start display at page:

Download "Custom Actions for argparse Documentation"

Felicia Charles
5 years ago
Views:

1 Custom Actions for argparse Documentation Release 0.4 Hai Vu October 26, 2015

3 Contents 1 Introduction 1 2 Information Folder Actions IP Actions Dictionary Action Examples Extending the Custom Actions More Ideas Samples extend_action.py folder_exists.py proper_ip.py dict_action_example.py Indices and tables 9 Python Module Index 11 i

4 ii

5 CHAPTER 1 Introduction The package argparse_actions provides a number of custom actions for use with the argparse module. 1

6 Custom Actions for argparse Documentation, Release Chapter 1. Introduction

7 CHAPTER 2 Information Source Location: bitbucket Package Location: pypi Latest Document: latestdoc 2.1 Folder Actions The folder actions implement folder-related actions. class argparse_actions.folderexistsaction(option_strings, dest, nargs=none, const=none, default=none, type=none, choices=none, required=false, help=none, metavar=none) Custom action: verify the argument to be a folder (directory). If not, raise a NonFolderError exception. The action will strip off trailing slashes from the folder s name. class argparse_actions.foldercreateaction(option_strings, dest, nargs=none, const=none, default=none, type=none, choices=none, required=false, help=none, metavar=none) Custom action: create a new folder if not exist. If the folder already exists, do nothing. The action will strip off trailing slashes from the folder s name. 2.2 IP Actions Below are custom actions which deal with IPv4 addresses class argparse_actions.properipformataction(option_strings, dest, nargs=none, const=none, default=none, type=none, choices=none, required=false, help=none, metavar=none) A custom action, used in conjunction with argparse to validate an IP address. validate_ip(ipvalue) Validate an IP address, generate exception if need be. 3

8 Custom Actions for argparse Documentation, Release Dictionary Action class argparse_actions.dictaction(option_strings, dest, **kwargs) The DictAction class enables parsing the command line as a dictionary. One application is to handle defines such as those offered by g++ 4 Chapter 2. Information

9 CHAPTER 3 Examples The following example, taken from samples/folder_actions.py demonstrates the use of a custom action to verify the existence of a folder, specified from the command line: import argparse import argparse_actions if name == ' main ': parser = argparse.argumentparser(description='custom Actions') parser.add_argument('directory', action=argparse_actions.folderexistsaction) try: args = parser.parse_args() print 'Directory exists: {0}'.format(args.directory) except argparse_actions.nonfoldererror as e: print 'Directory does not exist' print e In the next example from samples/proper_ip.py, we use the ProperIpFormatAction custom action to verify if an IP address from command line is properly formatted: import argparse import argparse_actions if name == ' main ': parser = argparse.argumentparser(description='custom Actions') parser.add_argument('ip', action=argparse_actions.properipformataction) try: args = parser.parse_args() print 'IP is properly formatted: {0}'.format(args.ip) except argparse_actions.invalidip as e: print 'IP is invalid: {0}'.format(e.ip) # This will display similar output: # print e 3.1 Extending the Custom Actions If you find a custom action that almost do what you want, you can 5

10 Custom Actions for argparse Documentation, Release Write your own from scratch 2. Submit an enhancement request 3. Extend the existing custom action I am not commenting on option 1 it is your choice. For option 2, I will be gladly to accept any reasonable request, but sometimes life happens and I might not response quickly enough. That leaves you with the third option of extending the custom action yourself. Don t worry, it is not that hard. In the next example, I will take the ProperIpFormatAction custom action and extend it to include localhost as one of the proper IP format: import argparse import argparse_actions class IpAndLocalhostAction(argparse_actions.ProperIpFormatAction): def call (self, parser, namespace, values, option_string=none): # Do our check: allow for 'localhost' if values == 'localhost': setattr(namespace, self.dest, values) else: # Super class to perform its check parent = super(ipandlocalhostaction, self) parent. call (parser, namespace, values, option_string) if name == ' main ': parser = argparse.argumentparser(description='custom Actions') parser.add_argument('ip', action=ipandlocalhostaction) try: args = parser.parse_args() print 'IP is valid: {0}'.format(args.ip) except argparse_actions.invalidip as e: print e Discussion: The first step is to create a new class (IpAndLocalhostAction), based on an existing custom action (argparse_actions.properipformataction, which is really a class itself) Define the function call to override the base custom action with your own logic. 3.2 More Ideas Here are a few ideas I have in mind, which I might implement: Extend ProperIpFormatAction to determine if and IP... Is reachable Provides some services such as HTTP or FTP Belongs to a particular list, such as the banned IP list Extend FolderExistsAction to determine if the folder is... Writable Empty A symbolic link 6 Chapter 3. Examples

11 CHAPTER 4 Samples 4.1 extend_action.py This sample demonstrates how to extend the existing custom action to add functionality. In this example, we will extend the ProperIpFormatAction class to accept localhost as a proper IP address. Examples: python extend_action.py python extend_action.py localhost 4.2 folder_exists.py This sample demonstrate the FolderExistsAction custom action. Examples: python folder_exists /tmp python folder_exists /foo/bar 4.3 proper_ip.py This sample demonstrate the ProperIpFormatAction custom action. Examples: python proper_ip.py python proper_ip.py dict_action_example.py Simulate a g++ define command line Examples: python dict_action_example -D log_level=debug warning_as_error python dict_action_example -Dverbose -D strict 7

12 Custom Actions for argparse Documentation, Release Chapter 4. Samples

13 CHAPTER 5 Indices and tables genindex modindex search 9

14 Custom Actions for argparse Documentation, Release Chapter 5. Indices and tables

15 Python Module Index init, 3 a argparse_actions, 3 d dict_action, 3 dict_action_example, 7 e extend_action, 7 f folder_actions, 3 folder_exists, 7 i ip_actions, 3 p proper_ip, 7 11

16 Custom Actions for argparse Documentation, Release Python Module Index

17 Index Symbols init (module), 3 A argparse_actions (module), 3 D dict_action (module), 3 dict_action_example (module), 7 DictAction (class in argparse_actions), 4 E extend_action (module), 7 F folder_actions (module), 3 folder_exists (module), 7 FolderCreateAction (class in argparse_actions), 3 FolderExistsAction (class in argparse_actions), 3 I ip_actions (module), 3 P proper_ip (module), 7 ProperIpFormatAction (class in argparse_actions), 3 V validate_ip() (argparse_actions.properipformataction method), 3 13

monolith Documentation

monolith Documentation Release 0.3.3 Łukasz Balcerzak December 16, 2013 Contents 1 Usage 3 1.1 Execution manager............................................ 3 1.2 Creating commands...........................................