Tutorial by Examples: ect

You can use the clearRect method to clear any rectangular section of the canvas. // Clear the entire canvas ctx.clearRect(0, 0, canvas.width, canvas.height); Note: clearRect is dependent on the transformation matrix. To deal with this, it's possible to reset the transformation matrix befor...

Writing a view to create object can be quite boring. You have to display a form, you have to validate it, you have to save the item or return the form with an error. Unless you use one of the generic editing views. app/views.py from django.core.urlresolvers import reverse_lazy from django.views.g...

Following the Rcpp example in this documentation entry, consider the following tough-to-vectorize function, which creates a vector of length len where the first element is specified (first) and each element x_i is equal to cos(x_{i-1} + 1): repeatedCosPlusOne <- function(first, len) { x <-...

SelectorDescription*Universal selector (all elements)divTag selector (all <div> elements).blueClass selector (all elements with class blue).blue.redAll elements with class blue and red (a type of Compound selector)#headlineID selector (the element with "id" attribute set to headline)...

The standard ADB configuration involves a USB connection to a physical device. If you prefer, you can switch over to TCP/IP mode, and connect ADB via WiFi instead. Not rooted device Get on the same network: Make sure your device and your computer are on the same network. Connect the...

Array.isArray(obj) returns true if the object is an Array, otherwise false. Array.isArray([]) // true Array.isArray([1, 2, 3]) // true Array.isArray({}) // false Array.isArray(1) // false In most cases you can instanceof to check if an object is an Array. []...

The protected keyword marks field, methods properties and nested classes for use inside the same class and derived classes only: public class Foo() { protected void SomeFooMethod() { //do something } protected class Thing { private string blah; ...

git clean -fd Will remove all untracked directories and the files within them. It will start at the current working directory and will iterate through all subdirectories. git clean -dn Will preview all directories that will be cleaned.

Often you'd be working with viewmodel classes in asp.net-mvc and would want to bind to properties on these. This works similar to mapping to individual parameters. Say you had a simple view model call PostViewModel like this public class PostViewModel{ public int Id {get;set;} public int Sn...

A syntactic extension that allows applying the tuple constructor (which is an operator) in a section way: (a,b) == (,) a b -- With TupleSections (a,b) == (,) a b == (a,) b == (,b) a N-tuples It also works for tuples with arity greater than two (,2,) 1 3 == (1,2,3) Mapping This can be u...

iex(1)> recompile Compiling 1 file (.ex) :ok

There are a number of collection types in Python. While types such as int and str hold a single value, collection types hold multiple values. Lists The list type is probably the most commonly used collection type in Python. Despite its name, a list is more like an array in other languages, mostl...

Each time you use a selector in jQuery the DOM is searched for elements that match your query. Doing this too often or repeatedly will decrease performance. If you refer to a specific selector more than once you should add it to the cache by assigning it to a variable: var nav = $('#navigation'); ...

/** * LoginController constructor. * @param Socialite $socialite */ public function __construct(Socialite $socialite) { $this->socialite = $socialite; } Within the constructor of your Controller, you're now able to inject the Socialite class that will help you handle login with so...

Avoid destructive operations on quoted objects. Quoted objects are literal objects. They are possibly embedded in the code in some way. How this works and the effects of modifications are unspecified in the Common Lisp standard, but it can have unwanted consequences like modifying shared data, tryin...

It is possible to mount a host directory to a specific path in your container using the -v or --volume command line option. The following example will mount /etc on the host to /mnt/etc in the container: (on linux) docker run -v "/etc:/mnt/etc" alpine cat /mnt/etc/passwd (on windows) do...

Adding properties If you'd like to add properties to an existing object, you can use the Add-Member cmdlet. With PSObjects, values are kept in a type of "Note Properties" $object = New-Object -TypeName PSObject -Property @{ Name = $env:username ID = 12 Address...

The array_intersect function will return an array of values that exist in all arrays that were passed to this function. $array_one = ['one', 'two', 'three']; $array_two = ['two', 'three', 'four']; $array_three = ['two', 'three']; $intersect = array_intersect($array_one, $array_two, $array_thre...

git difftool -t meld --dir-diff will show the working directory changes. Alternatively, git difftool -t meld --dir-diff [COMMIT_A] [COMMIT_B] will show the differences between 2 specific commits.

git diff myfile.txt Shows the changes between the previous commit of the specified file (myfile.txt) and the locally-modified version that has not yet been staged. This also works for directories: git diff documentation The above shows the changes between the previous commit of all files in ...