Tutorial by Examples: u

Python minimally evaluates Boolean expressions. >>> def true_func(): ... print("true_func()") ... return True ... >>> def false_func(): ... print("false_func()") ... return False ... >>> true_func() or false_func() true_func(...

# 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 *...

Given a String and a Character let text = "Hello World" let char: Character = "o" We can count the number of times the Character appears into the String using let sensitiveCount = text.characters.filter { $0 == char }.count // case-sensitive let insensitiveCount = text.low...

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...

Boolean(0) === false Boolean(0) will convert the number 0 into a boolean false. A shorter, but less clear, form: !!0 === false

If the values in a container have certain operators already overloaded, std::sort can be used with specialized functors to sort in either ascending or descending order: C++11 #include <vector> #include <algorithm> #include <functional> std::vector<int> v = {5,1,2,4,3};...

Managed resources are resources that the runtime's garbage collector is aware and under control of. There are many classes available in the BCL, for example, such as a SqlConnection that is a wrapper class for an unmanaged resource. These classes already implement the IDisposable interface -- it's u...

It's important to let finalization ignore managed resources. The finalizer runs on another thread -- it's possible that the managed objects don't exist anymore by the time the finalizer runs. Implementing a protected Dispose(bool) method is a common practice to ensure managed resources do not have t...

You can add a home page route to your app with the root method. # config/routes.rb Rails.application.routes.draw do root "application#index" # equivalent to: # get "/", "application#index" end # app/controllers/application_controller.rb class Applicati...

When a controller action is rendered, Rails will attempt to find a matching layout and view based on the name of the controller. Views and layouts are placed in the app/views directory. Given a request to the PeopleController#index action, Rails will search for: the layout called people in app/...

class UsersController < ApplicationController def index hashmap_or_array = [{ name: "foo", email: "[email protected]" }] respond_to do |format| format.html { render html: "Hello World" } format.json { render json: hashmap_or_array } en...

Assuming the route: resources :users, only: [:index] And the controller: class UsersController < ApplicationController def index respond_to do |format| format.html { render } end end end The view app/users/index.html.erb will be rendered. If the view is: Hello &lt...

This function runs an AJAX call using GET allowing us to send parameters (object) to a file (string) and launch a callback (function) when the request has been ended. function ajax(file, params, callback) { var url = file + '?'; // loop through object and assemble the url var notFirst ...

resources :photos do member do get 'preview' end collection do get 'dashboard' end end This creates the following routes in addition to default 7 RESTful routes: get '/photos/:id/preview', to: 'photos#preview' get '/photos/dashboards', to: '...

From guides.rubyonrails.org: Instead of generating a model directly . . . let's set up a scaffold. A scaffold in Rails is a full set of model, database migration for that model, controller to manipulate it, views to view and manipulate the data, and a test suite for each of the above. Here's a...

To separate a URL into its individual components, use parse_url(): $url = 'http://www.example.com/page?foo=1&bar=baz#anchor'; $parts = parse_url($url); After executing the above, the contents of $parts would be: Array ( [scheme] => http [host] => www.example.com [path...

The StringBuffer, StringBuilder, Formatter and StringJoiner classes are Java SE utility classes that are primarily used for assembling strings from other information: The StringBuffer class has been present since Java 1.0, and provides a variety of methods for building and modifying a "buf...

git config --global merge.conflictstyle diff3 Sets the diff3 style as default: instead of the usual format in conflicted sections, showing the two files: <<<<<<< HEAD left ======= right >>>>>>> master it will include an additional section containi...

Rails files - and Ruby files in general - should be named with lower_snake_case filenames. E.g. app/controllers/application_controller.rb is the file that contains the ApplicationController class definition. Note that while PascalCase is used for class and module names, the files in which they r...

Generics types can have more than one type parameters, eg. Result is defined like this: pub enum Result<T, E> { Ok(T), Err(E), }