Context Managers in Python Post: 302954900

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Top Forums Shell Programming and Scripting Context Managers in Python Post 302954900 by Aia on Saturday 12th of September 2015 01:00:19 PM

09-12-2015

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A Context Manager is any class that must, at least, implement a __enter__() method and a __exit__() method. The purpose of this class is to setup, or build up an object and tear it down when you are done with it.
The __enter__() method would initialize the object, it would utilized the try, except and finally statements, and it would produce a proper return.
The __exit__() method would do the proper clean up after the object is not necessary any longer.

A common example of using a Context Manager is with opening files.
If you do it manually, you would have to do the checks necessary: that the file exists, that it can be accessed and opened, etc. After that you need to release the object file by closing it. This setup and tear-down action can be taken care of, nicely, using a Context Manager.

Last edited by Aia; 09-12-2015 at 08:57 PM..

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lp-shell

lp-shell(1)						      General Commands Manual						       lp-shell(1)

NAME

       lp-shell - Open an interactive launchpadlib shell.

SYNOPSIS

       lp-shell [-a] [-cPROGRAM] [--python] [--ipython] [service] [LP API version]

DESCRIPTION

       lp-shell opens an interactive Python shell with a launchpadlib.Launchpad object "lp" which is ready for use.

       It  authenticates against Launchpad with the consumer name "udt-lp-shell". When using lp-shell with the -a option it will use the anonymous
       login from launchpadlib.Launchpad.

       By default lp-shell connects to the "production" Launchpad service using the "1.0" LP API version.

       If you want to connect to another Launchpad service, call lp-shell with the service name as the second argument. lp-shell supports all ser-
       vices known by launchpadlib Python module.  Currently known are (list can be incomplete or outdated): "production", "staging", "dogfood".

       A  different  LP  API version can be selected by passing the API version to use as the third argument. Current supported are: "beta", "1.0"
       and "devel".

OPTIONS

       -a     Login anonymously into Launchpad.

       -c PROGRAM
	      Don't enter a shell but only run the specified Python program and exit.

       --ipython
	      Use an ipython shell if available (default).

       --python
	      Use a regular python shell.

AUTHORS

       lp-shell was written by Martin Pitt <martin.pitt@ubuntu.com>.

       It is released under the terms of the GNU General Public License, version 2 or (at your option) any later version.

lptools 							   27 March 2010						       lp-shell(1)