Tutorial by Examples: sin

Any data structure that supports __getitem__ can have their nested structure formatted: person = {'first': 'Arthur', 'last': 'Dent'} '{p[first]} {p[last]}'.format(p=person) # 'Arthur Dent' Object attributes can be accessed using getattr(): class Person(object): first = 'Zaphod' la...

Lambda functions in C++ are syntactic sugar that provide a very concise syntax for writing functors. As such, equivalent functionality can be obtained in C++03 (albeit much more verbose) by converting the lambda function into a functor: // Some dummy types: struct T1 {int dummy;}; struct T2 {int ...

Due to Node's asynchronous nature, creating or using a directory by first: checking for its existence with fs.stat(), then creating or using it depending of the results of the existence check, can lead to a race condition if the folder is created between the time of the check and the time of ...

The nodemon package makes it possible to automatically reload your program when you modify any file in the source code. Installing nodemon globally npm install -g nodemon (or npm i -g nodemon) Installing nodemon locally In case you don't want to install it globally npm install --save-dev nodemo...

JSFiddle: https://jsfiddle.net/UnsungHero97/80qod7aL/2/ HTML <div class="box_shadow"></div> CSS .box_shadow { background-color: #1C90F3; width: 200px; height: 100px; margin: 50px; } .box_shadow:after { content: ""; width: 190px; height: ...

The specifier override has a special meaning in C++11 onwards, if appended at the end of function signature. This signifies that a function is Overriding the function present in base class & The Base class function is virtual There is no run time significance of this specifier as is mainl...

child.py import time def main(): print "starting work" time.sleep(1) print "work work work work work" time.sleep(1) print "done working" if __name__ == '__main__': main() parent.py import os def main(): for i in range(5):...

This assumes you have a twilio account and have purchased/reserved a phone number... If you are using bundler add the following line to your Gemfile to include twilio-ruby in your project: gem 'twilio-ruby' otherwise enter gem install twilio-ruby on the command line. You might need sudo if you'...

EXTENDED_ARG = 145 # All opcodes greater than this have 2 operands HAVE_ARGUMENT = 90 # All opcodes greater than this have at least 1 operands cmp_op = ('<', '<=', '==', '!=', '>', '>=', 'in', 'not in', 'is', 'is ... # A list of comparator id's. The indecies are used as opera...

Enum constants are instantiated when an enum is referenced for the first time. Therefore, that allows to implement Singleton software design pattern with a single-element enum. public enum Attendant { INSTANCE; private Attendant() { // perform some initialization routine ...

You can validate any object, even plain ruby. class User include ActiveModel::Validations attr_reader :name, :age def initialize(name, age) @name = name @age = age end validates :name, presence: true validates :age, numericality: { only_integer: true, greater_than...

To list installed packages: $ pip list # example output docutils (0.9.1) Jinja2 (2.6) Pygments (1.5) Sphinx (1.1.2) To list outdated packages, and show the latest version available: $ pip list --outdated # example output docutils (Current: 0.9.1 Latest: 0.10) Sphinx (Current: 1.1.2 Late...

When adding indented code blocks inside a list you first need a blank line, then to indent the code further. Different flavours of Markdown have different rules for this. StackExchange requires code to be indented by 8 characters instead of the usual 4. (Spaces replaced with * for clarity): 1...

uvloop is an implementation for the asyncio.AbstractEventLoop based on libuv (Used by nodejs). It is compliant with 99% of asyncio features and is much faster than the traditional asyncio.EventLoop. uvloop is currently not available on Windows, install it with pip install uvloop. import asyncio i...

import locale locale.setlocale(locale.LC_ALL, '') Out[2]: 'English_United States.1252' locale.currency(762559748.49) Out[3]: '$762559748.49' locale.currency(762559748.49, grouping=True) Out[4]: '$762,559,748.49'

First of all, we need to add our first Fragment at the beginning, we should do it in the onCreate() method of our Activity: if (null == savedInstanceState) { getSupportFragmentManager().beginTransaction() .addToBackStack("fragmentA") .replace(R.id.container, FragmentA.n...

sed -i s/"what to replace"/"with what to replace"/g $file We use -i to select in-place editing on the $file file. In some systems it is required to add suffix after -i flag which will be used to create backup of original file. You can add empty string like -i '' to omit the b...

Let's say you have a vector like so: (def my-vec [1 2 3 4 5 6]) And you want to extract the first 3 elements and get the remaining elements as a sequence. This can be done as follows: (let [[x y z & remaining] my-vec] (println "first:" x ", second:" y "third:&quot...

# For Python 2 compatibility. from __future__ import print_function import lxml.html import requests def main(): r = requests.get("https://httpbin.org") html_source = r.text root_element = lxml.html.fromstring(html_source) # Note root_element.xpath() gives a *...

Add gem to the Gemfile: gem 'devise' Then run the bundle install command. Use command $ rails generate devise:install to generate required configuration file. Set up the default URL options for the Devise mailer in each environment In development environment add this line: config.action_mailer...