Argparse, and linking to methods in Subclasses

Karim karim.liateni at free.fr
Mon Jul 18 13:27:18 CEST 2011


with global:

  SERVER = None

A the end of Argparse declarations:
parser_check.set_defaults(action=do_the_check)

parser_build.set_defaults(action=do_the_build)

Then declare the action functions:

def do_the_check(namespace_args):
     if not SERVER:
         SERVER = Server(namespace_arg.type_of_server)
     SERVER.check()

def do_the_build(namespace_args):
     if not SERVER:
         SERVER = Server(namespace_arg.type_of_server)
     SERVER.build()

If I correctly understood your issue.

Regards
Karim



On 07/18/2011 03:48 AM, Victor Hooi wrote:
> Hi,
>
> I have a simple Python script to perform operations on various types on in-house servers:
>
> manage_servers.py<operation>  <type_of_server>
>
> Operations are things like check, build, deploy, configure, verify etc.
>
> Types of server are just different types of inhouse servers we use.
>
> We have a generic server class, then specific types that inherit from that:
>
> class Server
>      def configure_logging(self, loggin_file):
>          ...
>      def check(self):
>          ...
>      def deploy(self):
>          ...
>      def configure(self):
>          ...
>      def __init__(self, hostname):
>          self.hostname = hostname
>          logging = self.configure_logging(LOG_FILENAME)
> class SpamServer(Server):
>      def check(self):
>          ...
> class HamServer(Server):
>      def deploy(self):
>          ...
>
> My question is how to link that all up to argparse?
>
> Originally, I was using argparse subparses for the operations (check, build, deploy) and another argument for the type.
>
> subparsers = parser.add_subparsers(help='The operation that you want to run on the server.')
> parser_check = subparsers.add_parser('check', help='Check that the server has been setup correctly.')
> parser_build = subparsers.add_parser('build', help='Download and build a copy of the execution stack.')
> parser_build.add_argument('-r', '--revision', help='SVN revision to build from.')
> ...
> parser.add_argument('type_of_server', action='store', choices=types_of_servers,
>                      help='The type of server you wish to create.')
>
> Normally, you'd link each subparse to a method - and then pass in the type_of_server as an argument. However, that's slightly backwards due to the classes- I need to create an instance of the appropriate Server class, then call the operation method inside of that.
>
> Any ideas of how I could achieve the above? Perhaps a different design pattern for Servers? Or a way to use argparse in this situation?
>
> Thanks,
> Victor




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