Tutorial by Examples: le

git add -A 2.0 git add . In version 2.x, git add . will stage all changes to files in the current directory and all its subdirectories. However, in 1.x it will only stage new and modified files, not deleted files. Use git add -A, or its equivalent command git add --all, to stage all ch...

You can make Git ignore certain files and directories — that is, exclude them from being tracked by Git — by creating one or more .gitignore files in your repository. In software projects, .gitignore typically contains a listing of files and/or directories that are generated during the build proces...

Setting a specific Seed will create a fixed random-number series: random.seed(5) # Create a fixed state print(random.randrange(0, 10)) # Get a random integer between 0 and 9 # Out: 9 print(random.randrange(0, 10)) # Out: 4 Resetting the seed will create the same &qu...

import java.awt.Image; import javax.imageio.ImageIO; ... try { Image img = ImageIO.read(new File("~/Desktop/cat.png")); } catch (IOException e) { e.printStackTrace(); }

x > y x < y These operators compare two types of values, they're the less than and greater than operators. For numbers this simply compares the numerical values to see which is larger: 12 > 4 # True 12 < 4 # False 1 < 4 # True For strings they will compare lexicographical...

Use the import statement: >>> import random >>> print(random.randint(1, 10)) 4 import module will import a module and then allow you to reference its objects -- values, functions and classes, for example -- using the module.name syntax. In the above example, the random module...

Instead of importing the complete module you can import only specified names: from random import randint # Syntax "from MODULENAME import NAME1[, NAME2[, ...]]" print(randint(1, 10)) # Out: 5 from random is needed, because the python interpreter has to know from which resource it...

from module_name import * for example: from math import * sqrt(2) # instead of math.sqrt(2) ceil(2.7) # instead of math.ceil(2.7) This will import all names defined in the math module into the global namespace, other than names that begin with an underscore (which indicates that the wri...

If you ignore files by using a pattern but have exceptions, prefix an exclamation mark(!) to the exception. For example: *.txt !important.txt The above example instructs Git to ignore all files with the .txt extension except for files named important.txt. If the file is in an ignored folder, y...

Instead of this lambda-function that calls the method explicitly: alist = ['wolf', 'sheep', 'duck'] list(filter(lambda x: x.startswith('d'), alist)) # Keep only elements that start with 'd' # Output: ['duck'] one could use a operator-function that does the same: from operator import metho...

The Promise.all() static method accepts an iterable (e.g. an Array) of promises and returns a new promise, which resolves when all promises in the iterable have resolved, or rejects if at least one of the promises in the iterable have rejected. // wait "millis" ms, then resolve with &quot...

The Promise.race() static method accepts an iterable of Promises and returns a new Promise which resolves or rejects as soon as the first of the promises in the iterable has resolved or rejected. // wait "milliseconds" milliseconds, then resolve with "value" function resolve(va...

One can give a function as many arguments as one wants, the only fixed rules are that each argument name must be unique and that optional arguments must be after the not-optional ones: def func(value1, value2, optionalvalue=10): return '{0} {1} {2}'.format(value1, value2, optionalvalue1) Wh...

A Left Outer Join (also known as a Left Join or Outer Join) is a Join that ensures all rows from the left table are represented; if no matching row from the right table exists, its corresponding fields are NULL. The following example will select all departments and the first name of employees that ...

min, max, and sorted all need the objects to be orderable. To be properly orderable, the class needs to define all of the 6 methods __lt__, __gt__, __ge__, __le__, __ne__ and __eq__: class IntegerContainer(object): def __init__(self, value): self.value = value def __rep...

class MyClass { func sayHi() { print("Hello") } deinit { print("Goodbye") } } When a closure captures a reference type (a class instance), it holds a strong reference by default: let closure: () -> Void do { let obj = MyClass() // Captures a strong re...

In Python, variables inside functions are considered local if and only if they appear in the left side of an assignment statement, or some other binding occurrence; otherwise such a binding is looked up in enclosing functions, up to the global scope. This is true even if the assignment statement is ...

There are several special variable types that a class can use for more easily sharing data. Instance variables, preceded by @. They are useful if you want to use the same variable in different methods. class Person def initialize(name, age) my_age = age # local variable, will be destroyed ...

We have three methods: attr_reader: used to allow reading the variable outside the class. attr_writer: used to allow modifying the variable outside the class. attr_accessor: combines both methods. class Cat attr_reader :age # you can read the age but you can never change it attr_writer...

Ruby has three access levels. They are public, private and protected. Methods that follow the private or protected keywords are defined as such. Methods that come before these are implicitly public methods. Public Methods A public method should describe the behavior of the object being created. T...