Tutorial by Examples: l

With the Class Based generic Views, it is very simple and easy to create the CRUD views from our models. Often, the built in Django admin is not enough or not preferred and we need to roll our own CRUD views. The CBVs can be very handy in such cases. The CreateView class needs 3 things - a model, t...

Starting with a three-dimensional list: alist = [[[1,2],[3,4]], [[5,6,7],[8,9,10], [12, 13, 14]]] Accessing items in the list: print(alist[0][0][1]) #2 #Accesses second element in the first list in the first list print(alist[1][1][2]) #10 #Accesses the third element in the second list in...

Here is a simple example of an XAML page in WPF. It consists of a Grid, a TextBlock and a Button - the most common elements in XAML. <Window x:Class="FirstWpfApplication.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x=&q...

Introduction and motivation Expression templates (denoted as ETs in the following) are a powerful template meta-programming technique, used to speed-up calculations of sometimes quite expensive expressions. It is widely used in different domains, for example in implementation of linear algebra ...

There are two different types of descriptors. Data descriptors are defined as objects that define both a __get__() and a __set__() method, whereas non-data descriptors only define a __get__() method. This distinction is important when considering overrides and the namespace of an instance's dictiona...

The widely used combination of tic and toc can provide a rough idea of the execution time of a function or code snippets. For comparing several functions it shouldn't be used. Why? It is almost impossible to provide equal conditions for all code snippets to compare within a script using above solu...

The OverloadedStrings language extension allows the use of normal string literals to stand for Text values. {-# LANGUAGE OverloadedStrings #-} import qualified Data.Text as T myText :: T.Text myText = "overloaded"

{-# LANGUAGE OverloadedStrings #-} import qualified Data.Text as T myText :: T.Text myText = "mississippi" splitOn breaks a Text up into a list of Texts on occurrences of a substring. ghci> T.splitOn "ss" myText ["mi","i","ippi"] sp...

By default, GHCI's prompt shows all the modules you have loaded into your interactive session. If you have many modules loaded this can get long: Prelude Data.List Control.Monad> -- etc The :set prompt command changes the prompt for this interactive session. Prelude Data.List Control.Monad&g...

GHCi uses a configuration file in ~/.ghci. A configuration file consists of a sequence of commands which GHCi will execute on startup. $ echo ":set prompt \"foo> \"" > ~/.ghci $ ghci GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration...

The :l or :load command type-checks and loads a file. $ echo "f = putStrLn \"example\"" > example.hs $ ghci GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help ghci> :l example.hs [1 of 1] Compiling Main ( example.hs, interpreted ) Ok, modules ...

Lets suppose you have 2 Lists A and B, and you want to remove from B all the elements that you have in A the method in this case is List.removeAll(Collection c); #Example: public static void main(String[] args) { List<Integer> numbersA = new ArrayList<>(); List<Intege...

Reverse elements within a tuple colors = "red", "green", "blue" rev = colors[::-1] # rev: ("blue", "green", "red") colors = rev # colors: ("blue", "green", "red") Or using reversed (reversed gives an it...

def str = 'Single quoted string' assert str instanceof String

def str = "Double quoted string" assert str instanceof String

def param = 'string' def str = "Double quoted ${param}" assert str instanceof GString assert str == 'Double quoted string' The parameter is by default resolved eagerly, this means this applies: def param = 'string' def str = "Double quoted ${param}" param = 'another stri...

def str = '''multiline string''' assert str instanceof String

def str = ''' multiline string''' assert str.readLines().size() == 3

def str = '''\ multiline string''' assert str.readLines().size() == 2

def param = 'string' def str = """ multiline $param """ assert str instanceof GString assert str.readLines().size() == 3 assert str == ''' multiline string '''