![\"Layers\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2023\/03\/Layers.png\")
<\/p>\nThe layers pattern splits a task into horizontal layers. Each layer has a specific responsibility and provides a service to a higher layer.<\/p>\n
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The Layers Pattern is an architectural pattern that helps, according to the book “Pattern-Oriented Software Architecture, Volume 1″,<\/span><\/a> to bring structure into the mud.<\/p>\n <\/p>\n Although not specified, most layered architectures consist of three or four layers. Each layer is independent of the other layer. In the pure version, a layer can only access its layer below. A layer can not access its upper layer because it would create additional dependencies and complicates the control structure. Additionally, another application cannot easily use a layer that depends on an upper layer. A layer often provides its functionality by implementing the Facade Pattern<\/a>. The Facade Pattern provides a simplified interface to a complex system.<\/p>\n The Layers Pattern is heavily used since the beginning of software development. Consequentially, there are many use cases:<\/p>\n The Open Systems Interconnection model<\/b> (OSI model<\/b>) is a conce<\/a>ptual model<\/a> that ‘provides a common basis for the coordination of [ISO] standards development for the purpose of systems interconnection’.[2]<\/a><\/sup> In the OSI reference model, the communications between a computing system are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application<\/em>. (https:\/\/en.wikipedia.org\/wiki\/OSI_model<\/a>)<\/p>\n Chunte7, CC BY-SA 3.0 <https:\/\/creativecommons.org\/licenses\/by-sa\/3.0><\/a>, via Wikimedia Commons<\/p>\n <\/p>\n You may also very often hear about the simplified TCP\/IP model: The Internet protocol suite,<\/b> commonly known as TCP\/IP,<\/b> is a framework for organizing the set of communication protocols<\/a> used in the Internet<\/a> and similar computer networks<\/a> according to functional criteria. The foundational protocols in the suite are the Transmission Control Protocol<\/a> (TCP), the User Datagram Protocol<\/a> (UDP), and the Internet Protocol<\/a> (IP).<\/em> (https:\/\/en.wikipedia.org\/wiki\/Internet_protocol_suite<\/a>)<\/p>\n<\/p>\n When developing software for embedded systems, you typically use various layers of abstraction in C++.<\/p>\n Extending Python in C\/C++ consists of the following steps:<\/p>\n Embedding does the same reversely. What is happening on the Python and the C layer? Here is the simplified strategy.<\/p>\n<\/span>Also Known as<\/span><\/h3>\n
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<\/span>Context<\/span><\/h3>\n
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<\/span>Problem<\/span><\/h3>\n
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<\/span>Structure<\/span><\/h3>\n
![\"layersStructure\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2023\/03\/layersStructure.png\")
<\/p>\n![\"LayerCRC\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2023\/03\/LayerCRC.png\")
<\/p>\nClient<\/strong><\/code><\/p>\n\n
Layer J<\/strong><\/code><\/p>\n\n
<\/span>Examples<\/span><\/h3>\n
OSI Model and TCP\/IP Model<\/h4>\n
![\"Osi](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2023\/03\/Application_Layer.png\")
<\/p>\nEmbedded Systems<\/h4>\n
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Extend\/Embed Python in C\/C++<\/h4>\n
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int<\/code>, inherit from object<\/code>.<\/li>\n<\/ul>\n![\"object\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2023\/03\/object.png\")
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PyObject<\/code><\/a>. C is not object-oriented. PyObject<\/code> is a kind of the starting point of the Python object’s memory. You can study its implementation on GitHub: object.c<\/a><\/code>. PyObject<\/code> essentially has a reference counter and a pointer to the corresponding type.<\/li>\n<\/ul>\n