Python Refactor

Python Refactor :

Rules:

    General :

1.         Follow PEP8 Standard
2.         DRY - Dont Repeat Yourself ie., not more than 2 times
3.         1 Function / method should perform only 1 thing
4.         Use helper functions (small functions)
5.         Simplicity (logic , naming etc )

    Functions/Method:

1.         big functions are bad
2.         group related methods / variables in a file
3.         split or merge methods / functions using refactor feature in IDE

    Classes/Objects:

1.         Hide/Expose logic using middeleman classes
2.         Separate general and specific code in a class
3.         objects should not talk to strangers
4.         Use parent-child class whenever method/variables is repeated across different classes

    Others:

1.         breaking 1 big expression in conditional statements into simple statments
2.         Use named tuple to mini classes for data segregation

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Tools:

1.     Linters (Quality Checker):             Pylint , PEP8 and McCabe
2.     Formatters (Formatter):                 Autopep8
3.     Style Checkers(recommendations):    pycodestyle , pydocstyle Eg: pycodestyle file.py
4.     Pycharm(Refactor):                    In Editor > Rt ck >refactor

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Anti Patterns :    

    1. Too much code in a function/method
    2. Implementation of OOP / Not correct application of OOP /Too much OOP
    3. Duplicate Code
    4. Avoiding intertwine code
    5. Rename variables ie., do not use v1 ,v2 etc.,
    6. Avoid useless /non-operational code
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Design Patterns in OOP:

    1. If subclasses need not be modifiedby others , than instantion of child object inside parent class and make parent method static.
     2. Instead of having checks to returm certain value , you can create a null class which returns null /empty/relavent value and instantiate that instead.Instead of actual classs.
    3.Replace conditional with subclasses
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Law of Demeter

 the Law of Demeter for functions requires that a method m of an object O may only invoke the methods of the following kinds of objects:

    O itself
        public class ClassOne {
            public void method1() {method2();}
            public void method2() {}
        }

    m's parameters
        public class ClassOne {
            public void method1(ClassTwo classTwo) {
                classTwo.method2();
            }
        }
        class ClassTwo {
            public void method2() {   }
        }

    Any objects created/instantiated within m
        public class ClassOne {       
            public void method1() {
                ClassTwo classTwo = new ClassTwo();
                classTwo.method2();
            }
        }
        class ClassTwo {       
            public void method2() {  }
        }

    O's direct component objects
        public class ClassOne {
            private ClassTwo classTwo;   
            public void method1() {
                classTwo = new ClassTwo();
                classTwo.method2();
            }
        }
        class ClassTwo {
            public void method2() { }
        }
    A global variable, accessible by O, in the scope of m
        public class ClassOne {
            public void method1() {
                classTwo.STATIC_INSTANCE.method2();
            }
        }
        class ClassTwo {
            public static final ClassTwo STATIC_INSTANCE = ...;
            public void method2() { }
        }
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

1. OOP is mainly used to organize your business logic while  
2. AOP helps to organize your non-functional things like Auditing, Logging, Transaction Management , Security etc. This way you can decouple your business logic with non-fictional logic that makes code cleaner.