Python Tricks

Python está lleno de pequeños "trucos" con los que puedes optimizar tu código y hacerlo más legible. Tal vez conozcas algunos, pero seguro aprenderás algo nuevo y útil.

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1. Python Tricks Steven Pineda Cortés Based on Dan Bader’s book
3. Most simple useful advice: a Comma
4. Make sure you use assertions “The proper use of assertions is to inform developers about unrecoverable errors in a program”.
5. Common errors with assertions 1. Don’t use it for data validation, use regular Exceptions. 2. Asserts which never fail.
6. Context Managers
7. Context Managers
8. Context Managers, when to use? • Safe acquisition and release of system resources. • Avoids resource leaks and makes code easier to read.
9. Underscores, Dunders and More
10. String formatting
11. String formatting, which to use? if strings_are_user_supplied: use = “TemplateStrings” elif PYTHON_VERSION >= 3.6: use = “Interoplation” else: use = “New style”
12. Functions are first-class citizens 1. Functions are objects (everything is). 2. Functions can be stored in data structures. 3. Functions can be passed to other functions! (high-order functions). 4. Functions can be nested. 5. Functions can capture local state. 6. Objects can behave like functions.
13. Functions are first-class citizens
14. Functions are first-class citizens
15. Lambda functions • Shortcut for declaring small anonymous functions. • Restricted to a single expression. • Don’t go crazy with them
16. Decorators • Allow you to extend and modify the behavior of a callable without permanently modifying the callable itself. • Any sufficiently generic functionality is a great candidate: ◦ Logging ◦ Enforcing access control and authentication ◦ Instrumentation and timing functions. ◦ Rate-limiting. ◦ Caching. ◦ More!
17. Decorators
18. Decorators
19. *args and **kwargs • You can create more flexible APIs with variable number of arguments. • Essential for decorators and other wrappers. • If we call the function with additional arguments, args will collect them as a tuple. • Likewise, kwargs will collect extra keyword arguments as a dictionary.
20. *args and **kwargs
21. Argument unpacking
22. “is” vs “==”
23. Every class needs a __repr__ • Python fallsback to repr if str is not defined. • print and format use str. • str should be readable. • repr should be unambiguous.
24. Defining your own Exceptions • First of all, use Exceptions! • Asking for permission instead of forgiveness. • Custom exceptions make it clearer. • You can use inheritance to have a hierarchy.
25. Cloning objects • Beware of shallow copying. • Use copy module for deep copies. • It works even for arbitrary objects
26. Cloning objects, for real.
27. Abstract classes • Abstract classes are useful. • Python is not very strict. • We are human. • The sooner we fail, the better.
28. Abstract classes • ABC ensures that derived classes implement methods from the base class. • Using ABC helps avoiding bugs and makes class hierarchies easier to maintain.
29. USE PEP-8 https://www.python.org/dev/peps/pep-0008/
30. Thanks!