Tutorial by Examples: u

It is possible to await multiple calls concurrently by first invoking the awaitable tasks and then awaiting them. public async Task RunConcurrentTasks() { var firstTask = DoSomethingAsync(); var secondTask = DoSomethingElseAsync(); await firstTask; await secondTask; } Alt...

If you want two or more arguments to be mutually exclusive. You can use the function argparse.ArgumentParser.add_mutually_exclusive_group(). In the example below, either foo or bar can exist but not both at the same time. import argparse parser = argparse.ArgumentParser() group = parser.add_mut...

Only when the foreach statement moves to the next item does the iterator block evaluate up to the next yield statement. Consider the following example: private IEnumerable<int> Integers() { var i = 0; while(true) { Console.WriteLine("Inside iterator: " + i...

To modify an existing column in Rails with a migration, run the following command: rails g migration change_column_in_table This will create a new migration file in db/migration directory (if it doesn’t exist already), which will contain the file prefixed with timestamp and migration file name w...

In Python 3 the cmp built-in function was removed, together with the __cmp__ special method. From the documentation: The cmp() function should be treated as gone, and the __cmp__() special method is no longer supported. Use __lt__() for sorting, __eq__() with __hash__(), and other rich compariso...

Function level annotations help IDEs identify return values or potentially dangerous code /** * Adds two numbers together. * * @param Int $a First parameter to add * @param Int $b Second parameter to add * @return Int */ function sum($a, $b) { return (int) $a + $b; } /** * ...

If a class extends another class and would use the same metadata, providing it @inheritDoc is a simple way for use the same documentation. If multiple classes inherit from a base, only the base would need to be changed for the children to be affected. abstract class FooBase { /** * @par...

There are two operators for filtering duplicates: emails.Distinct(); // Never see the same value twice emails.DistinctUntilChanged(); // Never see the same value twice in a row You can also pass in a predicate: emails.DistinctUntilChanged(x => x.Length); // Never see the same length email t...

Let's use *norm as an example. From the documentation: dnorm(x, mean = 0, sd = 1, log = FALSE) pnorm(q, mean = 0, sd = 1, lower.tail = TRUE, log.p = FALSE) qnorm(p, mean = 0, sd = 1, lower.tail = TRUE, log.p = FALSE) rnorm(n, mean = 0, sd = 1) So if I wanted to know the value of a standard no...

In order to define a variable inside a linq expression, you can use the let keyword. This is usually done in order to store the results of intermediate sub-queries, for example: int[] numbers = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; var aboveAverages = from number in numbers l...

The \b metacharacter To make it easier to find whole words, we can use the metacharacter \b. It marks the beginning and the end of an alphanumeric sequence*. Also, since it only serves to mark this locations, it actually matches no character on its own. *: It is common to call an alphanumeric sequ...

In order to enable a multidex configuration you need: to change your Gradle build configuration to use a MultiDexApplication or enable the MultiDex in your Application class Gradle configuration In app/build.gradle add these parts: android { compileSdkVersion 24 buildToolsVersion ...

The dexcount plugin counts methods and class resource count after a successful build. Add the plugin in the app/build.gradle: apply plugin: 'com.android.application' buildscript { repositories { mavenCentral() // or jcenter() } dependencies { classpath 'com.ge...

While in insert mode, press <C-o> to temporarily leave insert mode and execute a one-off normal command. Example <C-o>2w jumps to the second word to the left and returns to insert mode. Note: Repeating with . will only repeat the actions from returning to insert mode This allows for ...

C++11 introduced final specifier which forbids method overriding if appeared in method signature: class Base { public: virtual void foo() { std::cout << "Base::Foo\n"; } }; class Derived1 : public Base { public: // Overriding Base::foo void foo() f...

Detailed instructions on getting android-activity set up or installed.

The URLRequest and URLLoader classes work together to make requests from Flash to external resources. The URLRequest defines information about the request e.g. the request body and the request method type, and the URLLoader references this to perform the actual request and provide a means of being n...

The URLVariables class allows you to define data to be sent along with a URLRequest. Example: var variables:URLVariables = new URLVariables(); variables.prop = "hello"; variables.anotherProp = 10; var request:URLRequest = new URLRequest('http://someservice.com'); request.data = v...

The URLRequestMethod class contains constants for the various request types you can make. These constants are to be allocated to URLRequest's method property: var request:URLRequest = new URLRequest('http://someservice.com'); request.method = URLRequestMethod.POST; Note that only GET and POST...

When Flash makes a request for data from an external source, that operation is asynchronous. The most basic explanation of what this means is that the data loads "in the background" and triggers the event handler you allocate to Event.COMPLETE when it is received. This can happen at any po...