9 Unusual Design Patterns Interview Questions (with Answers)
- Design patterns are a well-described solution to the most commonly encountered problems which occur during software development.
- Filter pattern or Criteria pattern is a design pattern that enables developers to filter a set of objects using different criteria and chaining them in a decoupled way through logical operations.
- Filter design pattern is useful where you want to add filters dynamically or you are implementing multiple functionalities and most of them require different filter criteria to filter something.
- Observer pattern (also known as Publish-Subscribe Pattern) is used when there is one-to-many relationship between objects such as if one object is modified, its dependent objects are to be notified automatically.
- The Bridge pattern is designed to separate a class's interface from its implementation so you can vary or replace the implementation without changing the client code.
- In ES6, Maps use the Object.is() method to compare keys, just like Sets do with their values.
- Weak maps are used to store weak object references.
- You can also initialize a WeakMap with an array of arrays, just like a Map. The difference is that because every key must be an object, the first item in each array must be an object.
- An error will be thrown if you try to put a nonobject key inside a WeakMap. One possible use case for WeakMap could be when you are tracking DOM elements.
- And now, whenever a Car instance is destroyed, the key referencing that instance inside the privateCarsData will be garbage collected to free memory.
- Anytime you will want to use only object keys, weak maps will be your best choice.
Astronomers Discovered 12 New Moons Around Jupiter. Here's How
- Like, say, a dozen previously unknown moons orbiting Jupiter, the discovery of which was announced Tuesday by the International Astronomical Union.
- They needed time for follow-up observations, to see which of the space rocks moved like moons (i.e. in predictable orbits) and which did not.
- Tuesday's announcement makes it official: Sheppard and his colleagues have discovered 12 new objects orbiting Jupiter, bringing the grand total of known Jovian satellites to 79.
- And the peculiar orbit of one of those satellites, in particular—a small object, no more than half a mile across—could explain how many of Jupiter's other moons came to be.
- It was the faintest of the objects Sheppard's team observed, which makes it not only the palest Jovian moon ever discovered, but likely the smallest, as well.
Replicate immutable data in typescript with the ReplicationBuilder
- The ReplicationBuilder is a typescript tool to clone immutable data objects in a typesafe, refactorable and well readable way.
- In our single page applications we often use different implementations of redux to handle our application state.
- The more complex the data structures become, the more complex becomes the code that handles the immutable states when using Object.assign() or something like that.
- So my intention was to create a tool that can handle immutable data in a typesafe, refactorable and well readable way.
- The powerful keyof-feature introduced in Typescript 2.1 to lookup for objects properties in a typesafe way helped me a lot to solve that.
- The result i called ReplicationBuilder and is a typesafe, fluent API to build replications of an object.
- Together with some other small helpers its published in the npm package "typescript-immutable-helper".
- We strive for transparency and don't collect excess data.
How Object Storage is Solving the Healthcare Data Explosion
- To complicate things even more, healthcare organizations also must adhere to stringent regulatory requirements regarding data privacy and security protocols, including how long the data must be retained and how quickly it can be accessed.
- The HIPAA Privacy Rule requires covered entities — which includes most healthcare organizations — to apply appropriate administrative, technical and physical safeguards to protect the privacy of protected health information (PHI) for whatever period the data is retained.
- It is also easy to search and locate data with object storage simply by using the object’s ID or by querying the metadata in the object using an HTTP-based REST API.
- As the healthcare industry continues to store zettabytes of data, many organizations will continue to turn to object storage as a simple, cost-effective, scalable solution to fit their needs.
Robots Can't Hold Stuff Very Well. But You Can Help
- UC Berkeley and Siemens researchers have launched something called Dex-Net as a Service, a beta program that computes how and where a robot should grip objects like vases and turbine housings.
- “In other words, even if the robot is slightly off, if the object is slightly off, if the physics are slightly off, the grasp still has a high probability of success,” says Goldberg.
- In the presence of these uncertainties, the system calculates what would happen if the robot gripped an object at a certain spot—and lots of spots nearby.
- Calculating perturbations for many different grasps on just one spray bottle takes a whole lot of brain power.
- (Fog, get it?) Goldberg sees Dex-Net as a Service working like software as a service—something like Google Docs, where calculations are done in the cloud and beamed down to your computer.
What Is a Blazar? It’s Like Staring Down the Barrel of a Black Hole
- On Thursday, researchers announced that they’d caught a single, tiny, high-energy particle called a neutrino that had rained down on Earth from a supermassive black hole some 4 billion light-years away.
- As material in the disk falls toward the black hole, its gravitational energy can be converted to light, making the centers of these galaxies very bright and giving them the name active galactic nuclei (AGN).
- And in some ways, its behavior looked more like another mysterious object astronomers were finding — called quasars — than it did variable stars.
- By the mid-1990s, astronomers determined that blazars, quasars, and some other bright galaxy phenomena they observed were all in the same family of objects: active galactic nuclei.
- Since then, improving technology has allowed astronomers to study blazars and other active galactic nuclei in new and improved ways.