Tutorial by Examples: co

Declaring a variable const only prevents its value from being replaced by a new value. const does not put any restrictions on the internal state of an object. The following example shows that a value of a property of a const object can be changed, and even new properties can be added, because the ob...

You can initialize a constant by using the const keyword. const foo = 100; const bar = false; const person = { name: "John" }; const fun = function () = { /* ... */ }; const arrowFun = () => /* ... */ ; Important You must declare and initialize a constant in the same statement....

General syntax git push <remotename> <object>:<remotebranchname> Example git push origin master:wip-yourname Will push your master branch to the wip-yourname branch of origin (most of the time, the repository you cloned from). Delete remote branch Deleting the remote br...

.encode and .decode both have error modes. The default is 'strict', which raises exceptions on error. Other modes are more forgiving. Encoding >>> "£13.55".encode('ascii', errors='replace') b'?13.55' >>> "£13.55".encode('ascii', errors='ignore') b'13.55' ...

Sometimes, your template need a bit more of information. For example, we would like to have the user in the header of the page, with a link to their profile next to the logout link. In these cases, use the get_context_data method. views.py class BookView(DetailView): template_name = "boo...

You can create a tuple and use a switch like so: var str: String? = "hi" var x: Int? = 5 switch (str, x) { case (.Some,.Some): print("Both have values") case (.Some, nil): print("String has a value") case (nil, .Some): print("Int has a value&...

Assuming you have a model called Post defined in your models.py file that contains blog posts, and has a date_published field. Step 1: Write the context processor Create (or add to) a file in your app directory called context_processors.py: from myapp.models import Post def recent_blog_posts...

Following the Rcpp example in this documentation entry, consider the following tough-to-vectorize function, which creates a vector of length len where the first element is specified (first) and each element x_i is equal to cos(x_{i-1} + 1): repeatedCosPlusOne <- function(first, len) { x <-...

You can create widgets composed of multiple widgets using MultiWidget. from datetime import date from django.forms.widgets import MultiWidget, Select from django.utils.dates import MONTHS class SelectMonthDateWidget(MultiWidget): """This widget allows the user to fill in ...

This assumes that you have read the documentation about starting a new Django project. Let us assume that the main app in your project is named td (short for test driven). To create your first test, create a file named test_view.py and copy paste the following content into it. from django.test impo...

Getting the Constructor Object You can obtain Constructor class from the Class object like this: Class myClass = ... // get a class object Constructor[] constructors = myClass.getConstructors(); Where the constructors variable will have one Constructor instance for each public constructor decl...

If you have a f :: Lens' a b and a g :: Lens' b c then f . g is a Lens' a c gotten by following f first and then g. Notably: Lenses compose as functions (really they just are functions) If you think of the view functionality of Lens, it seems like data flows "left to right"—this might ...

Install gunicorn pip install gunicorn From django project folder (same folder where manage.py resides), run the following command to run current django project with gunicorn gunicorn [projectname].wsgi:application -b 127.0.0.1:[port number] You can use the --env option to set the pat...

What’s a component? A component is basically a directive that uses a simpler configuration and that is suitable for a component-based architecture, which is what Angular 2 is all about. Think of a component as a widget: A piece of HTML code that you can reuse in several different places in y...

OptionSetType is a protocol designed to represent bit mask types where individual bits represent members of the set. A set of logical and/or functions enforce the proper syntax: struct Features : OptionSet { let rawValue : Int static let none = Features(rawValue: 0) static let feature0 = F...

The standard ADB configuration involves a USB connection to a physical device. If you prefer, you can switch over to TCP/IP mode, and connect ADB via WiFi instead. Not rooted device Get on the same network: Make sure your device and your computer are on the same network. Connect the...

The const keyword declares a global constant binding. const DEADBEEF: u64 = 0xDEADBEEF; fn main() { println("{:X}", DEADBEEF); } This outputs DEADBEEF

TODO: Maybe move the explanations to remarks and add examples separately FOOF In Common Lisp, there is a concept of Generalized References. They allow a programmer to setf values to various "places" as if they were variables. Macros that make use of this ability often have a F-postfix in...

Macros return code. Since code in Lisp consists of lists, one can use the regular list manipulation functions to generate it. ;; A pointless macro (defmacro echo (form) (list 'progn (list 'format t "Form: ~a~%" (list 'quote form)) form)) This is often very hard to...

json.Marshal from the package "encoding/json" encodes a value to JSON. The parameter is the value to encode. The returned values are an array of bytes representing the JSON-encoded input (on success), and an error (on failure). decodedValue := []string{"foo", "bar"} ...