Tutorial by Examples: u

Python has several functions built into the interpreter. If you want to get information of keywords, built-in functions, modules or topics open a Python console and enter: >>> help() You will receive information by entering keywords directly: >>> help(help) or within the u...

Mongoose populate is used to show data for referenced documents from other collections. Lets say we have a Person model that has referenced documents called Address. Person Model var Person = mongoose.model('Person', { fname: String, mname: String, lname: String, address: {typ...

Racket functions can also have keyword arguments, which are specified with a keyword followed by the argument expression. A keyword begins with the characters #:, so a keyword argument looks like #:keyword arg-expr. Within a function call this looks like (function #:keyword arg-expr). > (define ...

iex> my_string = "Lorem ipsum dolor sit amet, consectetur adipiscing elit." iex> String.slice my_string, 6..10 "ipsum"

If you want to create and send signals in your own code (for example, if you are writing an extension), create a new Signal instance and call send when the subscribers should be notified. Signals are created using a Namespace. from flask import current_app from flask.signals import Namespace n...

First, references will be added to the CLR assemblies that will be used. import clr clr.AddReference('System.Windows.Forms') Next the names we will use are imported. from System.Windows.Forms import Application, Form A class will be created for the Hello World form using Form as its subclas...

Threads are the low level parts of a computing system which command processing occurs. It is supported/provided by CPU/MCU hardware. There are also software methods. The purpose of multi-threading is doing calculations in parallel to each other if possible. Thus the desired result can be obtained in...

Closures are inline anonymous methods that have the ability to use Parent method variables and other anonymous methods which are defined in the parent's scope. In essence, a closure is a block of code which can be executed at a later time, but which maintains the environment in which it was firs...

The IEnumerable<T> interface has a single method, GetEnumerator(), which returns an IEnumerator<T>. While the yield keyword can be used to directly create an IEnumerable<T>, it can also be used in exactly the same way to create an IEnumerator<T>. The only thing that changes ...

When an object implements the IDisposable interface, it can be created within the using syntax: using (var foo = new Foo()) { // do foo stuff } // when it reaches here foo.Dispose() will get called public class Foo : IDisposable { public void Dispose() { Console.WriteL...

Swift timer.fire() Objective-C [timer fire]; Calling the fire method causes an NSTimer to perform the task it would have usually performed on a schedule. In a non-repeating timer, this will automatically invalidate the timer. That is, calling fire before the time interval is up will result ...

5.1 JavaScript does not directly support enumerators but the functionality of an enum can be mimicked. // Prevent the enum from being changed const TestEnum = Object.freeze({ One:1, Two:2, Three:3 }); // Define a variable with a value from the enum var x = TestEnum.Two; // Prin...

For example, if t1 is currently not an InnoDB table, this statement changes its storage engine to InnoDB: ALTER TABLE t1 ENGINE = InnoDB; If the table is already InnoDB, this will rebuild the table and its indexes and have an effect similar to OPTIMIZE TABLE. You may gain some disk space improv...

The two functions fn1 and fn2 can return multiple tensors, but they have to return the exact same number and types of outputs. x = tf.constant(1.) bool = tf.constant(True) def fn1(): return tf.add(x, 1.), x def fn2(): return tf.add(x, 10.), x res1, res2 = tf.cond(bool, fn1, fn2)...

Functions in python are first-class objects. They can be defined in any scope def fibonacci(n): def step(a,b): return b, a+b a, b = 0, 1 for i in range(n): a, b = step(a, b) return a Functions capture their enclosing scope can be passed around like any other...

Below won't work on a Windows machine $file = $request->file('file_upload'); $sampleName = 'UserUpload'; $destination = app_path() . '/myStorage/'; $fileName = $sampleName . '-' . date('Y-m-d-H:i:s') . '.' . $file->getClientOriginalExtension(); $file->move($destination, $fileName); ...

The following values are considered falsey, in that they evaluate to False when applied to a boolean operator. None False 0, or any numerical value equivalent to zero, for example 0L, 0.0, 0j Empty sequences: '', "", (), [] Empty mappings: {} User-defined types where the __bool__ o...

There are three kinds of numeric RangeFields in Python. IntegerField, BigIntegerField, and FloatField. They convert to psycopg2 NumericRanges, but accept input as native Python tuples. The lower bound is included and the upper bound is excluded. class Book(models.Model): name = CharField(max_l...

add 'django.contrib.postgres' to your INSTALLED_APPS install psycopg2

It's simpler and easier to input values as a Python tuple instead of a NumericRange. Book.objects.create(name='Pro Git', ratings_range=(5, 5)) Alternative method with NumericRange: Book.objects.create(name='Pro Git', ratings_range=NumericRange(5, 5))