Tutorial by Examples: cas

Cask is a project management tool which can be also used to easily manage your local emacs configuration. Installing cask is easy. You can either run the following command on the command-line: curl -fsSL https://raw.githubusercontent.com/cask/cask/master/go | python Or if you are on a mac, you...

A pointer to a const object can be converted to a pointer to non-const object using the const_cast keyword. Here we use const_cast to call a function that is not const-correct. It only accepts a non-const char* argument even though it never writes through the pointer: void bad_strlen(char*); const...

If you're running a replica set or have a need to shard your database, you'll want an upstart script that looks something like this: # /etc/init/myapp.conf description "myapp.mydomain.com" author "[email protected]" # used to be: start on startup # until we found som...

BroadcastReceivers are used to receive broadcast Intents that are sent by the Android OS, other apps, or within the same app. Each Intent is created with an Intent Filter, which requires a String action. Additional information can be configured in the Intent. Likewise, BroadcastReceivers register ...

(u)gettext_noop allows you to mark a string as translatable without actually translating it. A typical use case is when you want to log a message for developers (in English) but also want to display it to the client (in the requested language). You can pass a variable to gettext, but its content wo...

LocalBroadcastManager is used to send Broadcast Intents within an application, without exposing them to unwanted listeners. Using LocalBroadcastManager is more efficient and safer than using context.sendBroadcast() directly, because you don't need to worry about any broadcasts faked by other Applic...

Assume you have a application that administers rooms. Assume further that your application operates on a per client basis (tenant). You have several clients. So your database will contain one table for clients, and one for rooms. Now, every client has N rooms. This should mean that you have...

UIBezierPath using to create a circular path ShapeLayer CAShapeLayer *circleLayer = [CAShapeLayer layer]; [circleLayer setPath:[[UIBezierPath bezierPathWithOvalInRect: CGRectMake(50, 50, 100, 100)] CGPath]]; circleLayer.lineWidth = 2.0; [circleLayer setStrokeColor:[[UIColor redColor] CGColor]];...

The System.String class supports a number of methods to convert between uppercase and lowercase characters in a string. System.String.ToLowerInvariant is used to return a String object converted to lowercase. System.String.ToUpperInvariant is used to return a String object converted to upper...

CAShapeLayer *circle = [CAShapeLayer layer]; [circle setPath:[[UIBezierPath bezierPathWithOvalInRect:CGRectMake(100, 100, 150, 150)] CGPath]]; [circle setStrokeColor:[[UIColor blueColor] CGColor]]; [circle setFillColor:[[UIColor clearColor] CGColor]]; [[self.view layer] addSublayer:circl...

select '123' * 2; To make the multiplication with 2 MySQL automatically converts the string 123 into a number. Return value: 246 The conversion to a number starts from left to right. If the conversion is not possible the result is 0 select '123ABC' * 2 Return value: 246 select 'A...

Then go into the mongo shell and initiate the replica set, like so: mongo > rs.initiate() PRIMARY> rs.add("mongo-a") PRIMARY> rs.add("mongo-b") PRIMARY> rs.add("mongo-c") PRIMARY> rs.setReadPref('secondaryPreferred')

The replica set will need an oplog user to access the database. mongo PRIMARY> use admin PRIMARY> db.addUser({user:"oplogger",pwd:"YOUR_PASSWORD",roles:[],otherDBRoles:{local:["read"]}}); PRIMARY> show users

Delete the local database files. Just exit the Mongo shell, navigate to the /dbpath (wherever you set it up), and delete the files within that directory.

Preparation $ mkdir globbing $ cd globbing $ mkdir -p folder/{sub,another}folder/content/deepfolder/ touch macy stacy tracy "file with space" folder/{sub,another}folder/content/deepfolder/file .hiddenfile $ shopt -u nullglob $ shopt -u failglob $ shopt -u dotglob $ shopt -u nocaseg...

sample on price increases: UPDATE ItemPrice SET Price = Price * CASE ItemId WHEN 1 THEN 1.05 WHEN 2 THEN 1.10 WHEN 3 THEN 1.15 ELSE 1.00 END

Sometimes we want to prepare a context for each test to be run under. The setUp method is run prior to each test in the class. tearDown is run at the end of every test. These methods are optional. Remember that TestCases are often used in cooperative multiple inheritance so you should be careful to...

With generics, it's possible to return whatever the caller expects: private Map<String, Object> data; public <T> T get(String key) { return (T) data.get(key); } The method will compile with a warning. The code is actually more safe than it looks because the Java runtime will d...

AWK often used for manipulating entire files containing a list of strings. Let's say file awk_test_file.txt contains: First String Second String Third String To convert all the strings to lower case execute: awk '{ print tolower($0) }' awk_test_file.txt This will result: first string se...

There is no revolution here, but angular constant can be useful specially when your application and/or team starts to grow ... or if you simply love writing beautiful code! Refactor code. Example with event's names. If you use a lot of events in your application, you have event's names a lit...