Tutorial by Examples: u

Say we have Products and Categorys in a many-to-many relationship: public class Product { public Product() { Categories = new HashSet<Category>(); } public int ProductId { get; set; } public string ProductName { get; set; } public virtual ICollection&lt...

The Fibonacci numbers are defined inductively as F0 = 0 F1 = 1 Fn+2 = Fn + Fn+1 The sum of the first n+1 Fibonacci numbers is given by F0 + F1 + F2 + ... + Fn = Fn+2 - 1. This summation arises, among other places, in the analysis of Fibonacci heaps, where it's used to provide a lower b...

You can animate complex changes to your collection view using the performBatchUpdates method. Inside the update block, you can specify several modifications to have them animate all at once. collecitonView.performBatchUpdates({ // Perform updates }, nil) Inside the update block, you can pe...

Before starting with the example I'd recommend to create a Singleton with a delegate class member so you could achieve a use case of uploading a file in the background and let the user keep using your app while the files are being uploaded even when the app is the background. Let's start, first, we...

If all you need is to wrap the value into a promise, you don't need to use the long syntax like here: //OVERLY VERBOSE var defer; defer = $q.defer(); defer.resolve(['one', 'two']); return defer.promise; In this case you can just write: //BETTER return $q.when(['one', 'two']); $q.when ...

C-h t runs the function help-with-tutorial, which opens a buffer containing a tutorial on the basic editing functionality of emacs, including moving around in text, and working with files, buffers, and windows.

Pressing C-h a will run the emacs function apropos-command which makes emacs prompt for words (or a regexp) to search for. It will then show a buffer containing a list of names and descriptions related to that topic, including key bindings for each of the functions available via keystrokes. Pressin...

C-h k runs the function describe-key, which looks up the function mapped to the key strokes provided, and presents a description of the function which will be run when these keys are pressed. C-h c runs the function describe-key-briefly, which only displays the function name mapped to given key seq...

C-h f runs the function describe-function, which displays information on the usage and purpose of a given function. This is especially useful for functions that do not have a mapped key binding that can be used for documentation lookup via C-h k.

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

Zip two arrays into an array of pairs: Prelude Data.Vector> Data.Vector.zip y y fromList [(0,0),(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9),(10,10),(11,11)] :: Data.Vector.Vector

These rules apply only if you use manual reference counting! You own any object you create By calling a method whose name begins with alloc, new, copy or mutableCopy. For example: NSObject *object1 = [[NSObject alloc] init]; NSObject *object2 = [NSObject new]; NSObject *object3 = [object2 ...

Here is a quick example of using multiple forms in one Django view. from django.contrib import messages from django.views.generic import TemplateView from .forms import AddPostForm, AddCommentForm from .models import Comment class AddCommentView(TemplateView): post_form_class = AddPo...

After you have opened a split window in vim (as demonstrated by many examples under this tag) then you will likely want to control windows quickly. Here is how to control split windows using keyboard shortcuts. Move to split Above/Below: Ctrl + w and k Ctrl + w and j Move to split Left/Right...

<?php $to = '[email protected]'; $subject = 'Sending an HTML email using mail() in PHP'; $message = '<html><body><p><b>This paragraph is bold.</b></p><p><i>This text is italic.</i></p></body></html>'; $headers =...

Many unbound generic parameters, like those used in a static method, cannot be recovered at runtime (see Other Threads on Erasure). However there is a common strategy employed for accessing the type satisfying a generic parameter on a class at runtime. This allows for generic code that depends on ac...

python-social-auth is a framework that simplifies the social authentication and authorization mechanism. It contains many social backends (Facebook, Twitter, Github, LinkedIn, etc.) INSTALL First we need to install the python-social-auth package with pip install python-social-auth or download ...

Synopsis A fully functional demo of Firebase v3 Web authentication viewable here. Sign in with Facebook, Github, Google, Twitter, password based, and anonymous accounts. The code, available on Github, is easy to read and follow and is well documented. The focus is on the fully functional authent...

Here is a quick reference for advanced insertion, formatting, and filtering commands/shortcuts. Command/ShortcutResultg + ? + mPerform rot13 encoding, on movement mn + ctrl + a+n to number under cursorn + ctrl + x-n to number under cursorg + q+ mFormat lines of movement m to fixed width:rce wCenter...