Python Programming Essentials - M37 - Brief Overview of Misc Concepts
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The document provides an overview of several Python programming concepts including pass by value vs reference, *args and **kwargs, hasattr and getattr, isinstance and issubclass, super, new-style vs old-style classes, properties, MRO (method resolution order), and pickle. It describes these concepts and provides examples of their usage.
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hasattr & getattr
hasattr – Check whether the object has an
attribute with the given name.
• hasattr(object, name) -> bool
getattr – Get a named attribute from an
object
• getattr(object, name[, default]) -> value](https://image.slidesharecdn.com/pythonprogrammingessentials-m37-briefoverviewofmiscconcepts-140819043231-phpapp01/85/Python-Programming-Essentials-M37-Brief-Overview-of-Misc-Concepts-7-320.jpg)
Python Programming Essentials - M37 - Brief Overview of Misc Concepts
- 1. http://www.skillbrew.com /SkillbrewTalent brewed by the industry itself Overview of some concepts Pavan Verma @YinYangPavan Founder, P3 InfoTech Solutions Pvt. Ltd. Python Programming Essentials
- 2. © SkillBrew http://skillbrew.com Pass by value or reference
- 3. © SkillBrew http://skillbrew.com Pass by value of reference Scalars (single-items) are passed by value • Numbers, strings Objects are passed by reference • Lists, tuples, dictionaries, class instances
- 4. © SkillBrew http://skillbrew.com * args and **kwargs
- 5. © SkillBrew http://skillbrew.com *args and **kwargs Ways to pass variable number of arguments to a function
- 7. © SkillBrew http://skillbrew.com hasattr & getattr hasattr – Check whether the object has an attribute with the given name. • hasattr(object, name) -> bool getattr – Get a named attribute from an object • getattr(object, name[, default]) -> value
- 9. © SkillBrew http://skillbrew.com isinstance & issubclass isinstance(object, class-or-type-or-tuple) -> bool Return whether an object is an instance of a class or of a subclass thereof. issubclass(C, B) -> bool Return whether class C is a subclass (i.e., a derived class) of class B
- 11. © SkillBrew http://skillbrew.com super Typically used to call a cooperative superclass method
- 12. © SkillBrew http://skillbrew.com New-Style vs Old-Style Classes
- 13. © SkillBrew http://skillbrew.com New-Style vs Old-Style Classes class NewStyleClass(object): pass class OldStyleClass(): pass
- 14. © SkillBrew http://skillbrew.com New-Style vs Old-Style Classes New-style classes motivated by need to provide a unified object model Provides ability to subclass most built-in types, or the introduction of "descriptors", which enable computed properties. Python 3 only has new-style classes. No matter if you subclass from object or not, classes are new-style in Python 3.
- 16. © SkillBrew http://skillbrew.com Property Allows user of the class to access data as attributes while hiding inner implementation details Helps whenever a user interface has granted attribute access and then subsequent changes require the intervention of a method
- 17. © SkillBrew http://skillbrew.com MRO – Method Resolution Order
- 18. © SkillBrew http://skillbrew.com MRO In case of multiple inheritance, need to define an algorithm for resolving a method name New-style classes: similar to breadth first search Old-style classes: depth first search Read more at https://www.python.org/download/releases/2. 3/mro/
- 20. © SkillBrew http://skillbrew.com Pickle The pickle module implements a fundamental, but powerful algorithm for serializing and de-serializing a Python object structure. “Pickling” is the process whereby a Python object hierarchy is converted into a byte stream, and “unpickling” is the inverse operation, whereby a byte stream is converted back into an object hierarchy. Pickling (and unpickling) is alternatively known as “serialization”, “marshalling,” or “flattening”, however, to avoid confusion, the terms used here are “pickling” and “unpickling”.