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You can restrict the valid types used in a generic class by bounding that type in the class definition. Given the following simple type hierarchy: public abstract class Animal { public abstract String getSound(); } public class Cat extends Animal { public String getSound() { ...

Sometimes it's necessary to be able to extract values from an object using only references (ie. without transferring ownership). struct Token { pub id: u32 } struct User { pub token: Option<Token> } fn main() { // Create a user with an arbitrary token let user = User...

Let's say we have the following data: >>> data = {"cats": [{"name": "Tubbs", "color": "white"}, {"name": "Pepper", "color": "black"}]} Just dumping this as JSON does not do anything special here: ...

Have a table NameAgeCityBob10ParisMat20BerlinMary24Prague select Name from table where Age>10 AND City='Prague' Gives NameMary select Name from table where Age=10 OR City='Prague' Gives NameBobMary

Light Table is a good editor to learn, experiment and run Clojure projects. You can also run lein/boot projects by opening project.clj file. It will load all project dependencies. It supports inline evalution, plugins and much more, so there's no need to add print statements and check the output i...

To setup Emacs for working with Clojure, install clojure-mode and cider package from melpa: M-x package-install [RET] clojure-mode [RET] M-x package-install [RET] cider [RET] Now when you open a .clj file, run M-x cider-jack-in to connect to a REPL. Alternatively, you can use C-u M-x (cider-jac...

Unlike the list, which is a sequential data structure, and the vector, which is both sequential and associative, the map is exclusively an associative data structure. A map consists of a set of mappings from keys to values. All keys are unique, so maps support "constant"-time lookup from k...

For if you have to fine-tune what is published. import { Mongo } from 'meteor/mongo'; import { Meteor } from 'meteor/meteor'; import { Random } from 'meteor/random'; if (Meteor.isClient) { // established this collection on the client only. // a name is required (first parameter) and this...

On the server, you can create a publication like this. this.userId is the id of the user who is currently logged in. If no user is logged in, you might want to throw an error and respond to it. import Secrets from '/imports/collections/Secrets'; Meteor.publish('protected_data', function () { ...

Swift 3 let stackView = UIStackView() stackView.axis = .horizontal stackView.alignment = .fill // .leading .firstBaseline .center .trailing .lastBaseline stackView.distribution = .fill // .fillEqually .fillProportionally .equalSpacing .equalCentering let label = UILabel() label.text = "...

Swift let stackView = UIStackView() stackView.axis = .Vertical stackView.alignment = .Fill // .Leading .FirstBaseline .Center .Trailing .LastBaseline stackView.distribution = .Fill // .FillEqually .FillProportionally .EqualSpacing .EqualCentering let label = UILabel(frame: CGRectZero) label....

You can take a snapshot from a UIView like this: Swift let snapshot = view.snapshotView(afterScreenUpdates: true) Objective-C UIView *snapshot = [view snapshotViewAfterScreenUpdates: YES];

Using the dateutil library as in the previous example on parsing timezone-aware timestamps, it is also possible to parse timestamps with a specified "short" time zone name. For dates formatted with short time zone names or abbreviations, which are generally ambiguous (e.g. CST, which coul...

By default all datetime objects are naive. To make them timezone-aware, you must attach a tzinfo object, which provides the UTC offset and timezone abbreviation as a function of date and time. Fixed Offset Time Zones For time zones that are a fixed offset from UTC, in Python 3.2+, the datetime mod...

It is often helpful to have MATLAB print the 1st line of a function, as this usually contains the function signature, including inputs and outputs: dbtype <functionName> 1 Example: >> dbtype fit 1 1 function [fitobj,goodness,output,warnstr,errstr,convmsg] = fit(xdatain,ydatain,f...

You can commit changes made to specific files and skip staging them using git add: git commit file1.c file2.h Or you can first stage the files: git add file1.c file2.h and commit them later: git commit

The boolean type cannot be cast to/from any other primitive type. A char can be cast to/from any numeric type by using the code-point mappings specified by Unicode. A char is represented in memory as an unsigned 16-bit integer value (2 bytes), so casting to byte (1 byte) will drop 8 of those bits (...

Numeric primitives can be cast in two ways. Implicit casting happens when the source type has smaller range than the target type. //Implicit casting byte byteVar = 42; short shortVar = byteVar; int intVar = shortVar; long longVar = intvar; float floatVar = longVar; double doubleVar = floatVar...

As with primitives, objects can be cast both explicitly and implicitly. Implicit casting happens when the source type extends or implements the target type (casting to a superclass or interface). Explicit casting has to be done when the source type is extended or implemented by the target type (ca...

In the material design, a Floating action button represents the primary action in an Activity. They are distinguished by a circled icon floating above the UI and have motion behaviors that include morphing, launching, and a transferring anchor point. Make sure the following dependency is added to ...