Python Tip - If you've accidentally deleted your .py files, all is not lost...

Recover .py files using uncompyle

If you've accidentally deleted your .py file, all is not lost. Use uncompyle to recover:

  git clone https://github.com/gstarnberger/uncompyle.git
  cd uncompyle/
  sudo ./setup.py install

  uncompyler.py thank_goodness_this_exists.pyc > recovered_file.py

See Also

• http://stackoverflow.com/questions/8189352/decompile-python-2-7-pyc

Python Tip - Create and detach a child process

Create and detach a child process

Use the following code to create and subsequently detach a child process

  DETACHED_PROCESS = 0x00000008
  pid = subprocess.Popen([sys.executable, "longtask.py"],
                         creationflags=DETACHED_PROCESS)

  pid.poll()  # Returns: None if child still active
              #          returncode otherwise 

In Sym, a complex component will be made up of a parent process and related child processes. 

See Also

• http://stackoverflow.com/questions/89228/calling-an-external-command-in-python
• http://docs.python.org/2/library/subprocess.html#module-subprocess
• http://stackoverflow.com/questions/13243807/popen-waiting-for-child-process-even-when-the-immediate-child-has-terminated
• http://msdn.microsoft.com/en-us/library/windows/desktop/ms684863.aspx

Useful Python Packages for Sym

List of useful Python Packages

1. Regular Expressions -- re
• Very powerful but takes a bit getting used to - Perl hackers should have no problems
2. Parsing HTML -- lxml | lxml+xpath
• Install from binaries for Windows platform 
• lxml expects a clean xml, use regular expressions if your input aren't clean
3. Logging -- logging  
4. GUI -- Tkinter | WxPython | Other GUI Toolkits 
5. JSON-driven GUI --  why? | pytkgen 
6. JSON schema -- why? | jsonschema | examples | other implementations