Tutorial by Examples: pt

The datetime module can convert a POSIX timestamp to a ITC datetime object. The Epoch is January 1st, 1970 midnight. import time from datetime import datetime seconds_since_epoch=time.time() #1469182681.709 utc_date=datetime.utcfromtimestamp(seconds_since_epoch) #datetime.datetime(2016, 7, 2...

The semantics for this are similar to that of default value substitution, but instead of substituting a default value, it errors out with the provided error message. The forms are ${VARNAME?ERRMSG} and ${VARNAME:?ERRMSG}. The form with : will error our if the variable is unset or empty, whereas the ...

DefaultIfEmpty is used to return a Default Element if the Sequence contains no elements. This Element can be the Default of the Type or a user defined instance of that Type. Example: var chars = new List<string>() { "a", "b", "c", "d" }; chars.Defaul...

TCO is only available in strict mode As always check browser and Javascript implementations for support of any language features, and as with any javascript feature or syntax, it may change in the future. It provides a way to optimise recursive and deeply nested function calls by eliminating the n...

ngOptions is a directive that simplifies the creation of a html dropdown box for the selection of an item from an array that will be stored in a model. The ngOptions attribute is used to dynamically generate a list of <option> elements for the <select> element using the array or object o...

There are a few ways to catch multiple exceptions. The first is by creating a tuple of the exception types you wish to catch and handle in the same manner. This example will cause the code to ignore KeyError and AttributeError exceptions. try: d = {} a = d[1] b = d.non_existing_fiel...

If you don't know which options you should use, you may be interested in the :options command. This will open a split with all Vim options listed and with their current value displayed. There are 26 sections to display all options you can try. e.g. 4 displaying text scroll number of lines t...

Array.prototype.map(): Returns a new array with the results of calling a provided function on every element in the original array. The following code example takes an array of persons and creates a new array containing persons with a 'fullName' property var personsArray = [ { id: 1, f...

A content script is extension code that runs alongside a normal page. They have full access to the web page's DOM (and are, in fact, the only part of the extension that can access a page's DOM), but the JavaScript code is isolated, a concept called Isolated World. Each extension has its own content...

Consider the following block of code. try { using (var disposable = new MyDisposable()) { throw new Exception("Couldn't perform operation."); } } catch (Exception ex) { Console.WriteLine(ex.Message); } class MyDisposable : IDisposable { public vo...

#!/bin/bash NO_SNAPSHOTS="No snapshots have been taken yet" SNAPSHOT_OUTPUT=$(vagrant snapshot list | grep "${NO_SNAPSHOTS}") if [ -z "${SNAPSHOT_OUTPUT}" ]; then echo "Found some snapshots, going to remove them" for SNAPSHOT in $(vagrant snap...

Versions Release Date VersionRelease Date8.2.4December 07, 20167.53December 07, 20166.38 (unsupported)February 24, 20165.23 (unsupported)August 11, 2010 Entity types In earlier versions of Drupal, the field system was only used on content types. Now, thanks to the Entity API, we can add fields...

The command prompt comes pre-installed on all Windows NT, Windows CE, OS/2 and eComStation operating systems, and exists as cmd.exe, typically located in C:\Windows\system32\cmd.exe On Windows 7 the fastest ways to open the command prompt are: Press , type "cmd" and then press Enter....

When custom options are merged, they use the default strategy, which simply overwrites the existing value. If you want a custom option to be merged using custom logic, you need to attach a function to Vue.config.optionMergeStrategies: Vue.config.optionMergeStrategies.myOption = function (toVal, fro...

When a mixin and the component itself contain overlapping options, they will be “merged” using appropriate strategies. For example, hook functions with the same name are merged into an array so that all of them will be called. In addition, mixin hooks will be called before the component’s own hooks:...

User input Imagine you want a user to enter a number via input. You want to ensure that the input is a number. You can use try/except for this: Python 3.x3.0 while True: try: nb = int(input('Enter a number: ')) break except ValueError: print('This is not a num...

One can extract a series of consecutive elements from an Array using a Range. let words = ["Hey", "Hello", "Bonjour", "Welcome", "Hi", "Hola"] let range = 2...4 let slice = words[range] // ["Bonjour", "Welcome", &quot...

C++11 NOTE: std::auto_ptr has been deprecated in C++11 and will be removed in C++17. You should only use this if you are forced to use C++03 or earlier and are willing to be careful. It is recommended to move to unique_ptr in combination with std::move to replace std::auto_ptr behavior. Before we ...

We can do two things to improve the simple and sub-optimal disjoint-set subalgorithms: Path compression heuristic: findSet does not need to ever handle a tree with height bigger than 2. If it ends up iterating such a tree, it can link the lower nodes directly to the root, optimizing future trav...

JSON stands for "JavaScript Object Notation", but it's not JavaScript. Think of it as just a data serialization format that happens to be directly usable as a JavaScript literal. However, it is not advisable to directly run (i.e. through eval()) JSON that is fetched from an external source...