Tutorial by Examples: ev

Declaration-site variance can be thought of as declaration of use-site variance once and for all the use-sites. class Consumer<in T> { fun consume(t: T) { ... } } fun charSequencesConsumer() : Consumer<CharSequence>() = ... val stringConsumer : Consumer<String> = cha...

Use-site variance is similar to Java wildcards: Out-projection: val takeList : MutableList<out SomeType> = ... // Java: List<? extends SomeType> val takenValue : SomeType = takeList[0] // OK, since upper bound is SomeType takeList.add(takenValue) // Error, lower bound for...

Assuming you created the serial port object s as in this example, then to close it fclose(s) However, sometimes you can accidentally lose the port (e.g. clear, overwrite, change scope, etc...), and fclose(s) will no longer work. The solution is easy fclose(instrfindall) More info at instrfin...

When you need to remove a specific value from an array, you can use the following one-liner to create a copy array without the given value: array.filter(function(val) { return val !== to_remove; }); Or if you want to change the array itself without creating a copy (for example if you write a fun...

execute the following command to insert the text into a view with a focus (if it supports text input) 6.0 Send text on SDK 23+ adb shell "input keyboard text 'Paste text on Android Device'" If already connected to your device via adb: input text 'Paste text on Android Device' 6...

A one-liner that helps granting or revoking vulnerable permissions. granting adb shell pm grant <sample.package.id> android.permission.<PERMISSION_NAME> revoking adb shell pm revoke <sample.package.id> android.permission.<PERMISSION_NAME> Granting all run...

It is common to want two views to be side by side, centered in their superview. The common answer given on Stack Overflow is to embed these two views in a UIView and center the UIView. This is not necessary or recommended. From the UILayoutGuide docs: There are a number of costs associated with...

The standard ADB configuration involves a USB connection to a physical device. If you prefer, you can switch over to TCP/IP mode, and connect ADB via WiFi instead. Not rooted device Get on the same network: Make sure your device and your computer are on the same network. Connect the...

The expansion of a macro often needs to use symbols that weren't passed as arguments by the user (as names for local variables, for example). One must make sure that such symbols cannot conflict with a symbol that the user is using in the surrounding code. This is usually achieved by using GENSYM, ...

Given some default routing such as {controller=Home}/{action=Index}/{id?} if you had the url https://stackoverflow.com/questions/1558902 This would go to the QuestionsController and the value 1558902 would be mapped to an id parameter of an index action, i.e. public ActionResult Index(int? id){ ...

If you want to develop and contribute to the Flask project, clone the repository and install the code in development mode. git clone ssh://github.com/pallets/flask cd flask python3 -m venv env source env/bin/activate pip install -e . There are some extra dependencies and tools to be aware ...

ViewData is the mechanism for a controller to provide data to the view it presents, without using a ViewModel. Specifically, ViewData is a dictionary which is available both in MVC action methods and views. You may use ViewData to transfer some data from your action method to the view returned by th...

Usually we want to separate the creation of the dialog from its appearance. Then three steps are needed. Create base element <div id="dialog" title="Basic dialog"> <p>This is the default dialog which is useful for displaying information. The dialog window can...

iex(1)> a = 10 10 iex(2)> b = 20 20 iex(3)> a + b 30 You can get a specific row passing the index of the row: iex(4)> v(3) 30 You can also specify an index relative to the current row: iex(5)> v(-1) # Retrieves value of row (5-1) -> 4 30 iex(6)> v(-5) # Retrieves...

There are a couple ways you can reverse a string to make it backwards. StringBuilder/StringBuffer: String code = "code"; System.out.println(code); StringBuilder sb = new StringBuilder(code); code = sb.reverse().toString(); System.out.println(code); Char array: S...

You can use the reversed function which returns an iterator to the reversed list: In [3]: rev = reversed(numbers) In [4]: rev Out[4]: [9, 8, 7, 6, 5, 4, 3, 2, 1] Note that the list "numbers" remains unchanged by this operation, and remains in the same order it was originally. To r...

Each enum class contains an implicit static method named values(). This method returns an array containing all values of that enum. You can use this method to iterate over the values. It is important to note however that this method returns a new array every time it is called. public enum Day { ...

Lambda expressions can be used to handle events, which is useful when: The handler is short. The handler never needs to be unsubscribed. A good situation in which a lambda event handler might be used is given below: smtpClient.SendCompleted += (sender, args) => Console.WriteLine("Ema...

To assign variables from the command-line, -v can be used: $ awk -v myvar="hello" 'BEGIN {print myvar}' hello Note that there are no spaces around the equal sign. This allows to use shell variables: $ shell_var="hello" $ awk -v myvar="$shell_var" 'BEGIN {print m...

Node Version Manager, otherwise known as nvm, is a bash script that simplifies the management of multiple Node.js versions. To install nvm, use the provided install script: $ curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.31.3/install.sh | bash For windows there is a nvm-windows p...