Laravel's events allows to implement the Observer pattern. This can be used to send a welcome email to a user whenever they register on your application.
New events and listeners can be generated using the artisan command line utility after registering the event and their particular listener in App...
A transaction acts on a single database connection. If you have multiple class-specific databases, the transaction will not protect interaction among them. One workaround is to begin a transaction on each class whose models you alter:
Student.transaction do
Course.transaction do
course.enro...
Both #save and #destroy come wrapped in a transaction that ensures that whatever you do in validations or callbacks will happen under its protected cover. So you can use validations to check for values that the transaction depends on or you can raise exceptions in the callbacks to rollback, includin...
User-defined functionals
Users can create their own functionals to varying degrees of complexity. The following examples are from Functionals by Hadley Wickham:
randomise <- function(f) f(runif(1e3))
lapply2 <- function(x, f, ...) {
out <- vector("list", length(x...
The number that follows the associativity information describes in what order the operators are applied. It must always be between 0 and 9 inclusive. This is commonly referred to as how tightly the operator binds. For example, consider the following fixity declarations (in base)
infixl 6 +
infixl ...
When matching the path of a route, you can do it explicitly, matching only one path, like so:
get "/hello" do
return "Hello!"
end
You can also use a regular expression to match complex routes. Any route which matches the regular expression will run that code block. If m...
When either a signed or unsigned integer is converted to a signed integer type, and its value is not representable in the destination type, the value produced is implementation-defined. Example:
// Suppose that on this implementation, the range of signed char is -128 to +127 and
// the range of un...
If you want to show local notification immediately, you should call:
Swift 3
UIApplication.shared.presentLocalNotificationNow(notification)
Swift 2
UIApplication.sharedApplication().presentLocalNotificationNow(notification)
Objective-C
[[UIApplication sharedApplication] presentLocalNotific...
public class OnSwipeListener implements View.OnTouchListener {
private final GestureDetector gestureDetector;
public OnSwipeListener(Context context) {
gestureDetector = new GestureDetector(context, new GestureListener());
}
@Override
public boolean onTouch(Vi...
Jagged Arrays NOT Multidimensional Arrays
Arrays of Arrays(Jagged Arrays) are not the same as Multidimensional Arrays if you think about them visually Multidimensional Arrays would look like Matrices (Rectangular) with defined number of elements on their dimensions(inside arrays), while Jagged arra...
Due to very specific way of actor instantiation, injecting dependencies into an actor instance is not trivial. In order to intervene in actor instantiation and allow Spring to inject dependencies one should implement a couple of akka extensions. First of those is an IndirectActorProducer:
import ak...
#demo-element {
background: @theme-color;
color: contrast(@theme-color, black, white, 50%);
}
@theme-color: red;
The above example will set the text color of the element as white if the background-color is dark and vice-versa. This is achieved using the contrast() color operation functi...
Put your dbname.sqlite or dbname.db file in assets folder of your project.
public class Databasehelper extends SQLiteOpenHelper {
public static final String TAG = Databasehelper.class.getSimpleName();
public static int flag;
// Exact Name of you db file that you put in as...
When a Google Map is displayed in lite mode clicking on a map will open the Google Maps application. To disable this functionality you must call setClickable(false) on the MapView, e.g.:
final MapView mapView = (MapView)view.findViewById(R.id.map);
mapView.setClickable(false);
Having more than one element with the same ID is a hard to troubleshoot problem. The HTML parser will usually try to render the page in any case. Usually no error occurs. But the pace could end up in a mis-behaving web page.
In this example:
<div id="aDiv">a</div>
<div id...
A spring bean can be configured such that it will register only if it has a particular value or a specified property is met. To do so, implement Condition.matches to check the property/value:
public class PropertyCondition implements Condition {
@Override
public boolean matches(ConditionC...
The Data.Vector module provided by the vector is a high performance library for working with arrays.
Once you've imported Data.Vector, it's easy to start using a Vector:
Prelude> import Data.Vector
Prelude Data.Vector> let a = fromList [2,3,4]
Prelude Data.Vector> a
fromList [2,3,4]...
Vectors can be map'd and fold'd,filter'd andzip`'d:
Prelude Data.Vector> Data.Vector.map (^2) y
fromList [0,1,4,9,16,25,36,49,64,81,100,121] :: Data.Vector.Vector
Reduce to a single value:
Prelude Data.Vector> Data.Vector.foldl (+) 0 y
66
