Tutorial by Examples: di

A condition variable is a primitive used in conjunction with a mutex to orchestrate communication between threads. While it is neither the exclusive or most efficient way to accomplish this, it can be among the simplest to those familiar with the pattern. One waits on a std::condition_variable with...

Passing a pointer argument to a T* parameter, if possible, is better than passing it to a const T* parameter. struct Base {}; struct Derived : Base {}; void f(Base* pb); void f(const Base* pb); void f(const Derived* pd); void f(bool b); Base b; f(&b); // f(Base*) is better than f(const...

An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. This will only compile if the destination type is long enough. The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer poin...

int main (void) { const int foo_readonly = 10; int *foo_ptr; foo_ptr = (int *)&foo_readonly; /* (1) This casts away the const qualifier */ *foo_ptr = 20; /* This is undefined behavior */ return 0; } Quoting ISO/IEC 9899:201x, section 6.7.3 §2: If an attempt i...

There are a couple of default recognizers available in Xamarin.Forms, one of them is the TapGestureRecognizer. You can add them to virtually any visual element. Have a look at a simple implementation which binds to an Image. Here is how to do it in code. var tappedCommand = new Command(() => {...

When you have a zoomed Image (or other content) you may want to drag around the Image to show all of its content in the zoomed in state. This can be achieved by implementing the PanGestureRecognizer. From code this looks like so: var panGesture = new PanGestureRecognizer(); panGesture.PanUpdated...

EntryPage.xaml: <?xml version="1.0" encoding="utf-8" ?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:vm="clr-namespace:MyAssembly.ViewModel;a...

You can simply use the native map APIs on each platform with Xamarin Forms. All you need is to download the Xamarin.Forms.Maps package from nuget and install it to each project (including the PCL project). Maps Initialization First of all you have to add this code to your platform-specific project...

Using the System.String.Contains you can find out if a particular string exists within a string. The method returns a boolean, true if the string exists else false. string s = "Hello World"; bool stringExists = s.Contains("ello"); //stringExists =true as the string contains t...

Create interface for clickHandler public interface ClickHandler { public void onButtonClick(View v); } Layout XML <?xml version="1.0" encoding="utf-8"?> <layout xmlns:android="http://schemas.android.com/apk/res/android"> <data> ...

Starting from a dataframe df: U L 111 en 112 en 112 es 113 es 113 ja 113 zh 114 es Imagine you want to add a new column called S taking values from the following dictionary: d = {112: 'en', 113: 'es', 114: 'es', 111: 'en'} You can use map to perform a lookup on keys returni...

The data can be imported directly into Hive: sqoop import --hive-import --table EventLog --connect "jdbc:sqlserver://192.168.1.99:1433;database=Test_db" --username user --password password --split-by id ...

db.collection.getIndexes(); Output [ { "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "documentation_db.transactions" }, { "v&quo...

This example discusses extending the below type class. trait Show[A] { def show: String } To make a class you control (and is written in Scala) extend the type class, add an implicit to its companion object. Let us show how we can get the Person class from this example to extend Show: class...

If we just try the following: import json from datetime import datetime data = {'datetime': datetime(2016, 9, 26, 4, 44, 0)} print(json.dumps(data)) we get an error saying TypeError: datetime.datetime(2016, 9, 26, 4, 44) is not JSON serializable. To be able to serialize the datetime object p...

Gradient Boosting for classification. The Gradient Boosting Classifier is an additive ensemble of a base model whose error is corrected in successive iterations (or stages) by the addition of Regression Trees which correct the residuals (the error of the previous stage). Import: from sklearn.ensem...

Follow this steps for adding splash screen into WPF application in Visual Studio: Create or get any image and add it to your project (e.g. inside Images folder): Open properties window for this image (View → Properties Window) and change Build Action setting to SplashScreen value: R...

ShortcutDescriptionCtrl + amove to the beginning of the lineCtrl + emove to the end of the lineCtrl + kKill the text from the current cursor position to the end of the line.Ctrl + uKill the text from the current cursor position to the beginning of the lineCtrl + wKill the word behind the current cur...

$ read -r foo <<EOF > this is a line >EOF $ printf '%s\n' "$foo" this is a line

ALTER TABLE table_name MOVE PARTITION partition_name TABLESPACE tablespace_name;