Command Design Pattern
Videos
| Section | Video Links |
|---|---|
| Command Overview |    |
| Command Use Case | |
| Single Leading Underscore | |
Book
Overview
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Terminology
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Command Pattern UML Diagram
Source Code
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Output
python ./command/command_concept.py Executing Command 1 Executing Command 2 Executing Command 1 Executing Command 2
Example Use Case
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Example UML Diagram
Output
python ./command/client.py Light turned ON Light turned OFF Light turned ON Light turned OFF 11:23:35 : ON 11:23:35 : OFF 11:23:35 : ON 11:23:35 : OFF Light turned ON Light turned OFF
New Coding Concepts
_Single Leading Underscore
The single leading underscore _variable, on your class variables is a useful indicator to other developers that this property should be considered private.
Private, in C style languages, means that the variable/field/property is hidden and cannot be accessed outside of the class. It can only be used internally by its own class methods.
Python does not have a public/private accessor concept so the variable is not actually private and can still be used outside of the class in other modules.
It is just a useful construct that you will see developers use as a recommendation not to reference this variable directly outside of this class, but use a dedicated method or property instead.
Summary
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