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Improper Inheritance Lets say there are 2 classes class Foo and Bar. Foo has two features Do1 and Do2. Bar needs to use Do1 from Foo, but it doesn't need Do2 or needs feature that is equivalent to Do2 but does something completely different. Bad way: make Do2() on Foo virtual then override it in B...

uses System.Character; var S1, S2: string; begin S1 := 'Foo'; S2 := ToLower(S1); // Convert the string to lower-case S1 := ToUpper(S2); // Convert the string to upper-case

To display "Some Text", use the command: echo Some Text This will output the string Some Text followed by a new line. To display the strings On and Off (case insensitive) or the empty string, use a ( instead of white-space: echo(ON echo( echo(off This will output: ON off ...

The echo setting determines whether command echoing is on or off. This is what a sample program looks like with command echoing on (default): C:\Windows\System32>echo Hello, World! Hello, World! C:\Windows\System32>where explorer C:\Windows\System32\explorer.exe C:\Windows\System32&gt...

Angular js directives can be nested or be made interoperable. In this example, directive Adir exposes to directive Bdir it's controller $scope, since Bdir requires Adir. angular.module('myApp',[]).directive('Adir', function () { return { restrict: 'AE', controlle...

enum Util { /* No instances */; public static int clamp(int min, int max, int i) { return Math.min(Math.max(i, min), max); } // other utility methods... } Just as enum can be used for singletons (1 instance classes), it can be used for utility classes (0 instance...

Once the type handlers are registered, everything should work automatically, and you should be able to use these types as either parameters or return values: string redmond = "POINT (122.1215 47.6740)"; DbGeography point = DbGeography.PointFromText(redmond, DbGeography.DefaultCoordi...

When using Access you can retrieve data using queries. These queries are built using Structured Query Language (SQL). Understanding SQL is important because it can help build better, more useful queries. When creating queries in Access, you can switch to "SQL View". An example of a "...

The BOM (Browser Object Model) contains objects that represent the current browser window and components; objects that model things like history, device's screen, etc The topmost object in BOM is the window object, which represents the current browser window or tab. Document: represents current...

The most important object in the Browser Object Model is the window object. It helps in accessing information about the browser and its components. To access these features, it has various methods and properties. MethodDescriptionwindow.alert()Creates dialog box with message and an OK buttonwindow....

An awk consists of patterns and actions, enclosed in curly brackets, to be taken if a pattern matches. The most basic pattern is the empty pattern, which matches any record. The most basic action is the empty action, which is equivalent to { print }, which is, in turn, equivalent to { print $0 }. If...

The http_build_query() will create a query string from an array or object. These strings can be appended to a URL to create a GET request, or used in a POST request with, for example, cURL. $parameters = array( 'parameter1' => 'foo', 'parameter2' => 'bar', ); $queryString = http_b...

Basic usage If the value of the href-attribute begins with mailto: it will try to open an email client on click: <a href="mailto:[email protected]">Send email</a> This will put the email address [email protected] as the recipient for the newly created email. Cc and ...

<PropertyGroup> <!-- Definition of a Property named "TestCondition". A PropertyGroup may also be placed inside a Target. --> <TestCondition>True</TestCondition> </PropertyGroup> <!-- This Target will run after the "Clean" Target, su...

We can read from a text file: dt <- fread("my_file.csv") Unlike read.csv, fread will read strings as strings, not as factors by default. See the [topic on fread][need_a_link] for more examples.

# example data DT = data.table(Titanic) Suppose we only want to see second class: DT[ Class == "2nd" ] # Class Sex Age Survived N # 1: 2nd Male Child No 0 # 2: 2nd Female Child No 0 # 3: 2nd Male Adult No 154 # 4: 2nd Female Adult ...

# example data DT = data.table(Titanic) Suppose we want to see each class only if a majority survived: DT[, if (sum(N[Survived=="Yes"]) > sum(N[Survived=="No"]) ) .SD, by=Class] # Class Sex Age Survived N # 1: 1st Male Child No 0 # 2: 1st Fema...

Match (node_name:node_type {}), (node_name_two:node_type_two {}) CREATE (node_name)-[::edge_name{}]->(node_name_two)

The DISTINCT clause after SELECT eliminates duplicate rows from the result set. CREATE TABLE `car` ( `car_id` INT UNSIGNED NOT NULL PRIMARY KEY, `name` VARCHAR(20), `price` DECIMAL(8,2) ); INSERT INTO CAR (`car_id`, `name`, `price`) VALUES (1, 'Audi A1', '20000'); INSERT INTO CA...

A quick note before actually installing RabbitMQ: Ubuntu 14.04's Erlang packages have issues if you are using SSL with RabbitMQ, so you'll need to install a newer version than what the Ubuntu package maintainers provide, so use the binaries at https://www.erlang-solutions.com/resources/download.html...