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https://github.com/jlengrand/observer
My (humble) implementation of the Observer pattern
https://github.com/jlengrand/observer
Last synced: about 10 hours ago
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My (humble) implementation of the Observer pattern
- Host: GitHub
- URL: https://github.com/jlengrand/observer
- Owner: jlengrand
- Created: 2012-07-18T18:24:23.000Z (over 12 years ago)
- Default Branch: master
- Last Pushed: 2012-10-26T14:48:52.000Z (about 12 years ago)
- Last Synced: 2023-03-12T09:06:46.105Z (over 1 year ago)
- Language: Python
- Size: 121 KB
- Stars: 2
- Watchers: 3
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Python Observer pattern using Json
This module contains a Python implementation of the Observer pattern, using json as a format to share information.
See [Wikipedia for more information]().
## Short description of the implementation
### Observer :
An observer is uniquey defined by its name. This allows Observable to only notify a given Observer if needed.
Observers can subscribe to an Observable and will then receive all future notifications from it.
The notifications are sent in json format.
### Observable :
An Observable is an entity holding information of interest for other entities.
Observers subscribe or unsubscribe to an Observable to get notified any time message is updated.
### JSon Structure:
As already explained, the messages sent from the observable to the observers are formatted as a JSon Object.
This allows a simple yet efficient control of the data sent and received while staying in line with the standards.
Each transmitted object should be divided into 4 sections:
- name : The name of the Observer to send the data to. As each Observer is uniquely defined by its name, filling this section means the data will be sent to **at most** one Observer.
- group : The group of Observers to send the data to. Each Observer may belong to a group. All Observers in the group will then be notified.
- type : the type of message contained in data. This section is not processed by the Observable and is sent as is. It may be blank, or contain anything.
- data : The actual data to be transmitted to the Observers
Here is are several examples of valid JSon message :
#### Data will be sent to Bob only. No particular message type
{
"name": 'Bob',
"group": '',
"type": '',
"data": 42
}
#### Data will be sent to all Observers in the GUI group. We may assess that this is an update :).
{
"name": '',
"group": 'GUI',
"type": 'Update',
"data": 'coffee'
}
#### No group, neither name specified. All subscribers will be notified. the message is an array of value object.
{
"name": '',
"group": '',
"type": '',
"data": ["baz", null, 1.0, 2]
}
According to the [JSon specifications](http://json.org/),
_A value can be a string in double quotes, or a number, or true or false or null, or an object or an array._
**NOTE:** group handling is currently not implemented.
In future improvements, It may also be possible to provide several names or group if needed.
## Description of the package
The Observer pattern does not need any external module to work. Any simple Python installation (>= 2.6) should be enough.
To use it, simply copy/paste the module file into your code base and load it in yuor code (import Observer)
You are then ready to go !
This package contains several other ressources :
- this README, only used to describe the package and give general information
- testObserver.py, the unit tests of the Observer/Obervable classes.
- exObserver.py, a simple example to show how the Observer pattern can be used.