Tutorial by Examples: e

Use associated type when there is a one-to-one relationship between the type implementing the trait and the associated type. It is sometimes also known as the output type, since this is an item given to a type when we apply a trait to it. Creation trait GetItems { type First; // ^~~~ d...

Rust's #[path] attribute can be used to specify the path to search for a particular module if it is not in the standard location. This is typically discouraged, however, because it makes the module hierarchy fragile and makes it easy to break the build by moving a file in a completely different dire...

Say you have implemented some logic to detect attempts to modify an object in the database while the client that submitted changes didn't have the latest modifications. If such case happens, you raise a custom exception ConfictError(detailed_message). Now you want to return an HTTP 409 (Confict) st...

Use the maxlen parameter while creating a deque to limit the size of the deque: from collections import deque d = deque(maxlen=3) # only holds 3 items d.append(1) # deque([1]) d.append(2) # deque([1, 2]) d.append(3) # deque([1, 2, 3]) d.append(4) # deque([2, 3, 4]) (1 is removed because i...

Creating empty deque: dl = deque() # deque([]) creating empty deque Creating deque with some elements: dl = deque([1, 2, 3, 4]) # deque([1, 2, 3, 4]) Adding element to deque: dl.append(5) # deque([1, 2, 3, 4, 5]) Adding element left side of deque: dl.appendleft(0) # deque([0, 1, 2, ...

A basic User Schema: var mongoose = require('mongoose'); var userSchema = new mongoose.Schema({ name: String, password: String, age: Number, created: {type: Date, default: Date.now} }); var User = mongoose.model('User', userSchema); Schema Types.

Methods can be set on Schemas to help doing things related to that schema(s), and keeping them well organized. userSchema.methods.normalize = function() { this.name = this.name.toLowerCase(); }; Example usage: erik = new User({ 'name': 'Erik', 'password': 'pass' }); erik.nor...

Often times you will see an exception Anti forgery token is meant for user "" but the current user is "username" This is because the Anti-Forgery token is also linked to the current logged-in user. This error appears when a user logs in but their token is still linked to bein...

String to a primitive numeric type or a numeric wrapper type: Each numeric wrapper class provides a parseXxx method that converts a String to the corresponding primitive type. The following code converts a String to an int using the Integer.parseInt method: String string = "59"; int p...

The tile pane layout is similar to the FlowPane layout. TilePane places all of the nodes in a grid in which each cell, or tile, is the same size. It arranges nodes in neat rows and columns, either horizontally or vertically. import javafx.application.Application; import javafx.scene.Scene;...

#Post to pagerduty.com notification pagerduty { post = https://events.pagerduty.com/generic/2010-04-15/create_event.json contentType = application/json runOnActions = false body = `{ "service_key": "myservicekey", "incident_key": {{.|jso...

The effect of using the * operator on an argument when calling a function is that of unpacking the list or a tuple argument def print_args(arg1, arg2): print(str(arg1) + str(arg2)) a = [1,2] b = tuple([3,4]) print_args(*a) # 12 print_args(*b) # 34 Note that the length of the starr...

Seaborn is a wrapper around Matplotlib that makes creating common statistical plots easy. The list of supported plots includes univariate and bivariate distribution plots, regression plots, and a number of methods for plotting categorical variables. The full list of plots Seaborn provides is in thei...

CSS ul { list-style: none; counter-reset: list-item-number; /* self nesting counter as name is same for all levels */ } li { counter-increment: list-item-number; } li:before { content: counters(list-item-number, ".") " "; /* usage of counters() function means val...

In many other languages, if you run the following (Java example) if("asgdsrf" == 0) { //do stuff } ... you'll get an error. You can't just go comparing strings to integers like that. In Python, this is a perfectly legal statement - it'll just resolve to False. A common gotcha ...

In the example of a message bubble illustrated below: the corners of the image should remain unchanged which is specified by UIEdgeInsets, but the borders and center of the image should expand to cover the new size. let insets = UIEdgeInsetsMake(12.0, 20.0, 22.0, 12.0) let image = UIImage(na...

<div tabindex="0">Some button</div> Note: Try to use a native HTML button or an a tag where appropriate.

<button tabindex="-1">This button will not be reachable by tab</button> The element will be removed from the tabbing order but will still be focusable.

<div tabindex="2">Second</div> <div tabindex="1">First</div> Positive values will insert the element at the tabbing order position of its respective value. Elements without preference (i.e. tabindex="0" or native elements such as button and a...

Build constraints are commonly used to separate normal unit tests from integration tests that require external resources, like a database or network access. To do this, add a custom build constraint to the top of the test file: // +build integration package main import ( "testing&...