Tutorial by Examples: sin

Increasing Animation Performance Using the `will-change` Attribute

When creating animations and other GPU-heavy actions, it's important to understand the will-change attribute. Both CSS keyframes and the transition property use GPU acceleration. Performance is increased by offloading calculations to the device's GPU. This is done by creating paint layers (parts of...

Prevent Receiving Your Own Messages Using Objective-C

Setting a filter applies to all channels that you will subscribe to from that particular client. This client filter excludes messages that have this subscriber's UUID set at the sender's UUID: NSString *expression = [NSString stringWithFormat:@"(uuid != '%@'", se...

Handling the error when getting metadata for a non-existing path using the Dropbox .NET library

This example uses the Dropbox .NET library to try to get the metadata for an item at a particular path, and checks for a NotFound error: try { var metadata = await this.client.Files.GetMetadataAsync("/non-existant path"); Console.WriteLine(metadata.Name); } catch (Dropbox.Api.A...

Squash Recent Commits Without Rebasing

If you want to squash the previous x commits into a single one, you can use the following commands: git reset --soft HEAD~x git commit Replacing x with the number of previous commits you want to be included in the squashed commit. Mind that this will create a new commit, essentially forgetting...

Using a stub to supply canned responses

A stub is a light weight test double that provides canned responses when methods are called. Where a class under test relies on an interface or base class an alternative 'stub' class can be implemented for testing which conforms to the interface. So, assuming the following interface, public inter...

Using a mocking framework as a stub

The terms Mock and Stub can often become confused. Part of the reason for this is that many mocking frameworks also provide support for creating Stubs without the verification step associated with Mocking. Rather than writing a new class to implement a stub as in the "Using a stub to supply c...

Using a mocking framework to validate behaviour

Mocks are used when it is necessary to verify the interactions between the system under test and test doubles. Care needs to be taken to avoid creating overly brittle tests, but mocking can be particularly useful when the method to test is simply orchestrating other calls. This test verifies that ...

Downloading a file using the Dropbox .NET library

This uses the Dropbox .NET SDK to download a file from the Dropbox API at the remote path /Homework/math/Prime_Numbers.txt to the local file Prime_Numbers.txt: using (var response = await client.Files.DownloadAsync("/Homework/math/Prime_Numbers.txt")) { using (var fileStream = File....

Creating a shared link for a file with expiration and visibility settings using the Dropbox Python library

This uses the Dropbox Python SDK to create a shared link for a file and also supplies a requested visibility and expiration in the settings: import datetime import dropbox dbx = dropbox.Dropbox("<ACCESS_TOKEN>") expires = datetime.datetime.now() + datetime.timedelta(days=30...

Using Boolean in if statement

Due to auto unboxing, one can use a Boolean in an if statement: Boolean a = Boolean.TRUE; if (a) { // a gets converted to boolean System.out.println("It works!"); } That works for while, do while and the condition in the for statements as well. Note that, if the Boolean is null...

Using lookbehind to test endings

A lookbehind can be used at the end of a pattern to ensure it ends or not in a certain way. ([a-z ]+|[A-Z ]+)(?<! ) matches sequences of only lowercase or only uppercase words while excluding trailing whitespace.

Using the @property decorator

The @property decorator can be used to define methods in a class which act like attributes. One example where this can be useful is when exposing information which may require an initial (expensive) lookup and simple retrieval thereafter. Given some module foobar.py: class Foo(object): def __...

Using the @property decorator for read-write properties

If you want to use @property to implement custom behavior for setting and getting, use this pattern: class Cash(object): def __init__(self, value): self.value = value @property def formatted(self): return '${:.2f}'.format(self.value) @formatted.setter def ...

Showcasing all common Angular constructs

The following example shows common AngularJS constructs in one file: <!DOCTYPE html> <html ng-app="myDemoApp"> <head> <style>.started { background: gold; }</style> <script src="https://code.angularjs.org/1.5.8/angular.min.js">&lt...

Merging, combine and composing Maps

Use putAll to put every member of one map into another. Keys already present in the map will have their corresponding values overwritten. Map<String, Integer> numbers = new HashMap<>(); numbers.put("One", 1) numbers.put("Three", 3) Map<String, Integer> othe...

Accessing memory beyond allocated chunk

A a pointer to a piece of memory containing n elements may only be dereferenced if it is in the range memory and memory + (n - 1). Dereferencing a pointer outside of that range results in undefined behavior. As an example, consider the following code: int array[3]; int *beyond_array = array + 3; ...

Class Inheritance

Inheritance works just like it does in other object-oriented languages: methods defined on the superclass are accessible in the extending subclass. If the subclass declares its own constructor then it must invoke the parents constructor via super() before it can access this. class SuperClass { ...

Creating a branch using direct URL to URL copy

Branching in Subversion is very simple. In the simplest form, creating a new branch requires you to run the command against the remote repository's URLs. For example, let's create a new branch out of the mainline trunk: svn copy https://svn.example.com/svn/MyRepo/MyProject/trunk https://svn.example...

Making changes in your local working copy

The working copy (WC) is your local and private workspace that you use to interact with the central Subversion repository. You use the working copy to modify the contents of your project and fetch changes committed by others. The working copy contains your project's data and looks and acts like a r...

Deleting a file using unlink or unlinkSync

Delete a file asynchronously: var fs = require('fs'); fs.unlink('/path/to/file.txt', function(err) { if (err) throw err; console.log('file deleted'); }); You can also delete it synchronously*: var fs = require('fs'); fs.unlinkSync('/path/to/file.txt'); console.log('file deleted'...

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