Tutorial by Examples: g

Sometimes developers write some code that desires access to stage, or Flash stage, to add listeners. It can work for the first time, then all of a sudden fail to work and produce the error 1009. The code in question can even be on the timeline, as it's the first initiative to add code there, and man...

addEventListener(Event.ENTER_FRAME,moveChild); function moveChild(e:Event):void { childMC.x++; if (childMC.x>1000) { gotoAndStop(2); } } This example will move the childMC (added to Main at design time) but will instantly throw a 1009 as soon as gotoAndStop() is invok...

interface ITable { // an indexer can be declared in an interface object this[int x, int y] { get; set; } } class DataTable : ITable { private object[,] cells = new object[10, 10]; /// <summary> /// implementation of the indexer declared in the interface //...

sqldf() from the package sqldf allows the use of SQLite queries to select and manipulate data in R. SQL queries are entered as character strings. To select the first 10 rows of the "diamonds" dataset from the package ggplot2, for example: data("diamonds") head(diamonds) #...

The JsonPipe can be used for debugging the state of any given internal. Code @Component({ selector: 'json-example', template: `<div> <p>Without JSON pipe:</p> <pre>{{object}}</pre> <p>With JSON pipe:</p> <pre>{{object | json...

This validation restricts the insertion of only numeric values. class Player < ApplicationRecord validates :points, numericality: true validates :games_played, numericality: { only_integer: true } end Besides :only_integer, this helper also accepts the following options to add constrai...

This helper validates that the specified attributes are not empty. class Person < ApplicationRecord validates :name, presence: true end Person.create(name: "John").valid? # => true Person.create(name: nil).valid? # => false You can use the absence helper to validate th...

Use following methods if you want to skip the validations. These methods will save the object to the database even if it is invalid. decrement! decrement_counter increment! increment_counter toggle! touch update_all update_attribute update_column update_columns update_counters You ca...

class Person < ApplicationRecord validates :name, length: { minimum: 2 } validates :bio, length: { maximum: 500 } validates :password, length: { in: 6..20 } validates :registration_number, length: { is: 6 } end The possible length constraint options are: :minimum - The attribut...

Unlike Big-O notation, which represents only upper bound of the running time for some algorithm, Big-Theta is a tight bound; both upper and lower bound. Tight bound is more precise, but also more difficult to compute. The Big-Theta notation is symmetric: f(x) = Ө(g(x)) <=> g(x) = Ө(f(x)) An ...

Overload resolution occurs after name lookup. This means that a better-matching function will not be selected by overload resolution if it loses name lookup: void f(int x); struct S { void f(double x); void g() { f(42); } // calls S::f because global f is not visible here, ...

While it might seem counterintuitive, you can use logical operators to determine whether or not a statement is run. For instance: File.exist?(filename) or STDERR.puts "#{filename} does not exist!" This will check to see if the file exists and only print the error message if it doesn't....

You can create parser error messages according to your script needs. This is through the argparse.ArgumentParser.error function. The below example shows the script printing a usage and an error message to stderr when --foo is given but not --bar. import argparse parser = argparse.ArgumentParser...

Boolean logic expressions, in addition to evaluating to True or False, return the value that was interpreted as True or False. It is Pythonic way to represent logic that might otherwise require an if-else test. And operator The and operator evaluates all expressions and returns the last expressi...

When you extend a class, you can override methods that the inherited class defines using the override keyword: public class Example { public function test():void { trace('It works!'); } } public class AnotherExample extends Example { public override function test():void ...

If you have your data stored in a list and you want to convert this list to a data frame the do.call function is an easy way to achieve this. However, it is important that all list elements have the same length in order to prevent unintended recycling of values. dataList <- list(1:3,4:6,7:9) ...

Number of unique elements in a series: In [1]: id_numbers = pd.Series([111, 112, 112, 114, 115, 118, 114, 118, 112]) In [2]: id_numbers.nunique() Out[2]: 5 Get unique elements in a series: In [3]: id_numbers.unique() Out[3]: array([111, 112, 114, 115, 118], dtype=int64) In [4]: df = pd.Da...

You can create your ssh key using ssh-keygen, it's a program that is part of the ssh installation. To do so just run it and follow the instructions on screen. Here's an example: $ ssh-keygen Generating public/private rsa key pair. The default directory where you ssh key pair will be saved is i...

Ever wanted to call a multicast delegate but you want the entire invokation list to be called even if an exception occurs in any in the chain. Then you are in luck, I have created an extension method that does just that, throwing an AggregateException only after execution of the entire list complete...

To increase the maximum amount of heap memory used Eclipse, edit the eclipse.ini file located in the Eclipse installation directory. This file specifies options for the startup of Eclipse, such as which JVM to use, and the options for the JVM. Specifically, you need to edit the value of the -Xmx JV...