Tutorial by Examples: nd

There are two functions that can be used to obtain a readable representation of an object. repr(x) calls x.__repr__(): a representation of x. eval will usually convert the result of this function back to the original object. str(x) calls x.__str__(): a human-readable string that describes the obje...

A simple example: CL-USER> (defun make-apply-twice (fun) "return a new function that applies twice the function`fun' to its argument" (lambda (x) (funcall fun (funcall fun x)))) MAKE-APPLY-TWICE CL-USER> (funcall (make-apply-twice #'1+) 3) 5 ...

Sometimes we need preserve whole model and transfer it across actions or even controllers. Storing model at session good solution for this type of requirements. If we combine this with powerful model binding features of MVC we get elegant way of doing so. We can create generic session based model bi...

NA is a logical type and a logical operator with an NA will return NA if the outcome is ambiguous. Below, NA OR TRUE evaluates to TRUE because at least one side evaluates to TRUE, however NA OR FALSE returns NA because we do not know whether NA would have been TRUE or FALSE NA | TRUE # [1] TRUE ...

Sometimes you may want maintain versions of a git repository on machines that have no network connection. Bundles allow you to package git objects and references in a repository on one machine and import those into a repository on another. git tag 2016_07_24 git bundle create changes_between_tags...

The year, month or day components of a DATE data type can be found using the EXTRACT( [ YEAR | MONTH | DAY ] FROM datevalue ) SELECT EXTRACT (YEAR FROM DATE '2016-07-25') AS YEAR, EXTRACT (MONTH FROM DATE '2016-07-25') AS MONTH, EXTRACT (DAY FROM DATE '2016-07-25') AS DAY FROM D...

Create new Jekyll Post To create a new Jekyll Post, create a new file on _posts directory with the format YYYY-MM-DD-title.MARKUP Replace MARKUP with the file extension for the language you want to use. This is usually Markdown(.md or .markdown) or HTML(.html). _posts/2017-01-01-hello-jekyll.m...

$sce ("Strict Contextual Escaping") is a built-in angular service that automatically sanitize content and internal sources in templates. injecting external sources and raw HTML into the template requires manual wrapping of$sce. In this example we'll create a simple $sce sanitation f...

The Ionic Platform offers a range of powerful, hybrid-focused mobile backend services and tools to make it easy to scale beautiful, performant hybrid apps, at a rapid pace. In order to use Ionic Platform you need to have the Ionic Framework installed. 1.) Registration (sign-up) You need to enter...

var regExp = new RegExp(r"(\w+)"); var str = "Parse my string"; Iterable<Match> matches = regExp.allMatches(str); It's a good idea to use "raw strings" (prefix with r) when writing regular expressions so you can use unescaped backslashes in your expression. ...

Locally created images can be pushed to Docker Hub or any other docker repo host, known as a registry. Use docker login to sign in to an existing docker hub account. docker login Login with your Docker ID to push and pull images from Docker Hub. If you don't have a Docker ID, head over to https...

Java provides a conditional-and and a conditional-or operator, that both take one or two operands of type boolean and produce a boolean result. These are: && - the conditional-AND operator, || - the conditional-OR operators. The evaluation of <left-expr> && <righ...

Imagine you are on the master branch and something is not working as expected (a regression was introduced), but you don't know where. All you know is, that is was working in the last release (which was e.g., tagged or you know the commit hash, lets take old-rel here). Git has help for you, finding...

In your Storyboard, add a UITableView object on your UIViewController and let it cover the entire view. Setup the UITableviewDataSource and UITableviewDelegate connections. Objective-C In your .h file NSMutableArray *arrayForBool; NSMutableArray *sectionTitleArray; In your .m file - (void)vi...

We can directly copy data from a source to a data sink using a loop. In this example, we are reading data from an InputStream and at the same time, writing to an OutputStream. Once we are done reading and writing, we have to close the resource. public void copy(InputStream source, OutputStream dest...

Channel uses a Buffer to read/write data. A buffer is a fixed sized container where we can write a block of data at once. Channel is a quite faster than stream-based I/O. To read data from a file using Channel we need to have the following steps- We need an instance of FileInputStream. FileInput...

let let num=1+2 let num="1+2" let 'num= 1 + 2' let num=1 num+=2 You need quotes if there are spaces or globbing characters. So those will get error: let num = 1 + 2 #wrong let 'num = 1 + 2' #right let a[1] = 1 + 1 #wrong let 'a[1] = 1 + 1' ...

Exit status 0: success Exit status other than 0: failure To test on the exit status of a command: if command;then echo 'success' else echo 'failure' fi

Vundle is a plugin manager for Vim. Installing Vundle (Full installation details can be found in the Vundle Quick Start) Install Git and clone Vundle into ~/.vim/bundle/Vundle.vim. Configure plugins by adding the following to the top of your .vimrc, adding or removing plugins as necessar...

Press controlr and type a pattern. For example, if you recently executed man 5 crontab, you can find it quickly by starting to type "crontab". The prompt will change like this: (reverse-i-search)`cr': man 5 crontab The `cr' there is the string I typed so far. This is an incremental s...