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The Decorator Pattern (or an implementation of this design pattern in Python - as the above example) should not be confused with Python Decorators, a language feature of Python. They are different things. Second to the Python Wiki: The Decorator Pattern is a pattern described in the Design Patterns Book.
The pattern is useful when exactly one object is needed to coordinate actions across a system. More specifically, the singleton pattern allows classes to: [2] Ensure they only have one instance; Provide easy access to that instance; Control their instantiation (for example, hiding the constructors of a class)
A snippet of Python code with keywords highlighted in bold yellow font. The syntax of the Python programming language is the set of rules that defines how a Python program will be written and interpreted (by both the runtime system and by human readers). The Python language has many similarities to Perl, C, and Java. However, there are some ...
With language-level support for delegation, this is done implicitly by having self in the delegate refer to the original (sending) object, not the delegate (receiving object). In the delegate pattern, this is instead accomplished by explicitly passing the original object to the delegate, as an argument to a method. [ 1 ] "
The service locator pattern is a design pattern used in software development to encapsulate the processes involved in obtaining a service with a strong abstraction layer. This pattern uses a central registry known as the "service locator", which on request returns the information necessary to perform a certain task. [ 1 ]
UnifiedPOS or UPOS is a world wide vendor- and retailer-driven Open Standard's initiative under the National Retail Federation, Association of Retail Technology Standards (NRF-ARTS) to provide vendor-neutral software application interfaces for numerous (as of 2011, thirty-six) point of sale (POS) peripherals (POS printer, cash drawer, magnetic stripe reader, bar code scanner, line displays, etc.).
Message passing is a technique for invoking behavior (i.e., running a program) on a computer. In contrast to the traditional technique of calling a program by name, message passing uses an object model to distinguish the general function from the specific implementations. The invoking program sends a message and relies on the object to select ...
Decorator dynamically adds/overrides behavior in an existing method of an object. Facade provides a simplified interface to a large body of code. Flyweight reduces the cost of creating and manipulating a large number of similar objects. Proxy provides a placeholder for another object to control access, reduce cost, and reduce complexity.