Tutorial by Examples: en

Blob Record From One Collection Into Another Collection (ie. Remove Join & Flatten)

db.posts.find().forEach(function(doc){ if(doc.commentsBlobId){ var commentsBlob = db.comments.findOne({'_id': commentsBlobId }); db.posts.update({_id: doc._id}, {$set:{'comments': commentsBlob }}, false, true); } });

meteor • Mongo Schema Migrations

Scrolling content with Auto Layout enabled

This project is a self-contained example done completely in the Interface Builder. You should be able to work through it in 10 minutes or less. Then you can apply the concepts you learned to your own project. Here I just use UIViews but they can represent whatever view you like (ie, button, label...

iOS • UIScrollView

Creating a Sequence: Example

Purpose Use the CREATE SEQUENCE statement to create a sequence, which is a database object from which multiple users may generate unique integers. You can use sequences to automatically generate primary key values. When a sequence number is generated, the sequence is incremented, independent of th...

Oracle Database • Sequences

Use $state.transitionTo to transition between states

Use $state.transitionTo to go form one state to another. This is a low level method to transition and $state.go is the recommended way for most common use cases as it uses this method internally. $state.transitionTo(toState [, toParams] [, options]) toState - the state to transition to toPara...

angular-ui-router • State transition

External parsed entities

XML fragments, also known under the name of external parsed entities, can be stored in separate files. XML fragments, unlike XML documents, are less restrictive, in that several elements can appear top-level, as well as text nodes. Like an XML document, an external parsed entity may begin with an X...

xml • Entities

Different ways to specify the classpath

There are three ways to set the classpath. It can be set using the CLASSPATH environment variable : set CLASSPATH=... # Windows and csh export CLASSPATH=... # Unix ksh/bash It can be set on the command line as follows java -classpath ... javac -classpath ... Note ...

Java Language • The Classpath

Simple mask that fades an image from solid to transparent

CSS div { height: 200px; width: 200px; background: url(http://lorempixel.com/200/200/nature/1); mask-image: linear-gradient(to right, white, transparent); } HTML <div></div> In the above example there is an element with an image as its background. The mask that is a...

CSS • Clipping and Masking

Use of instanceof with Generics

Using generics to define the type in instanceof Consider the following generic class Example declared with the formal parameter <T>: class Example<T> { public boolean isTypeAString(String s) { return s instanceof T; // Compilation error, cannot use T as class type here ...

Java Language • Generics

Conversion between pointer types produces incorrectly aligned result

The following might have undefined behavior due to incorrect pointer alignment: char *memory_block = calloc(sizeof(uint32_t) + 1, 1); uint32_t *intptr = (uint32_t*)(memory_block + 1); /* possible undefined behavior */ uint32_t mvalue = *intptr; The undefined behavior happens as the pointer...

C Language • Undefined behavior

Common control sequences in format strings

While there are many different control sequences for io:format and io_lib:format, most of the time you'll use only three different ones: ~s, ~p and ~w. ~s The ~s is for strings. It prints strings, binaries and atoms. (Anything else will cause a badarg error.) It doesn't quote or escape anything...

Erlang Language • Format Strings

Opening Zip Files

To start, import the zipfile module, and set the filename. import zipfile filename = 'zipfile.zip' Working with zip archives is very similar to working with files, you create the object by opening the zipfile, which lets you work on it before closing the file up again. zip = zipfile.ZipFile(fi...

Python Language • Working with ZIP archives

Renaming all files in the current directory

The following uses a variable with a for loop to rename a group of files. SetLocal EnableDelayedExpansion for %%j in (*.*) do ( set filename=%%~nj set filename=!filename:old=new! set filename=Prefix !filename! set filename=!filename! Suffix ren "%%j" "!filename!%%~x...

batch-file • For Loops in Batch Files

D3.js component with ReactJS

This example is based on a blog post by Nicolas Hery. It utilizes ES6 classes and ReactJS's lifecycle methods to keep the D3 component updated d3_react.html <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Hello, d3React!</title>...

d3.js • Using D3 with other frameworks

Reflog references: @{}

$ git show @{1} # uses reflog for current branch $ git show master@{1} # uses reflog for branch 'master' $ git show HEAD@{1} # uses 'HEAD' reflog A ref, usually a branch or HEAD, followed by the suffix @ with an ordinal specification enclosed in a brace pair (e.g. {1}, {1...

Git • Git revisions syntax

Reflog references: @{}

$ git show master@{yesterday} $ git show HEAD@{5 minutes ago} # or HEAD@{5.minutes.ago} A ref followed by the suffix @ with a date specification enclosed in a brace pair (e.g. {yesterday}, {1 month 2 weeks 3 days 1 hour 1 second ago} or {1979-02-26 18:30:00}) specifies the value of the ref at ...

Git • Git revisions syntax

Dereferencing branches and tags: ^0, ^{}

In some cases the behavior of a command depends on whether it is given branch name, tag name, or an arbitrary revision. You can use "de-referencing" syntax if you need the latter. A suffix ^ followed by an object type name (tag, commit, tree, blob) enclosed in brace pair (for example v0.9...

Git • Git revisions syntax

Code Folding Preferences

It is possible to change Code Folding preference to suit your need. Thus code folding can be set enable/unable for specific constructs (ex: if block, for loop, Sections ...). To change folding preferences, go to Preferences -> Code Folding: Then you can choose which part of the code can be f...

MATLAB Language • Useful tricks

Different ways for implementing a Generic Interface (or extending a Generic Class)

Suppose the following generic interface has been declared: public interface MyGenericInterface<T> { public void foo(T t); } Below are listed the possible ways to implement it. Non-generic class implementation with a specific type Choose a specific type to replace the formal type ...

Java Language • Generics

Generating Random Numbers with a Specified Seed

//Creates a Random instance with a seed of 12345. Random random = new Random(12345L); //Gets a ThreadLocalRandom instance ThreadLocalRandom tlr = ThreadLocalRandom.current(); //Set the instance's seed. tlr.setSeed(12345L); Using the same seed to generate random numbers will return the sa...

Java Language • Random Number Generation

Jetty Downloads and Documentation

The current release version of Jetty is 9.4. Support is still provided for Jetty 9.2 and 9.3, and maintenance releases are provided for Jetty 7 and Jetty 8 when needed. The most up-to-date distributions can be found on the Jetty Downloads page. It is worth noting that current releases of Jetty requ...

jetty • Official Jetty Resources