Tutorial by Examples: access

If you want to retrieve the details of a user's Facebook profile, you need to set permissions for the same: loginButton = (LoginButton)findViewById(R.id.login_button); loginButton.setReadPermissions(Arrays.asList("email", "user_about_me")); You can keep adding more permiss...
The first thing you need to do is create a connection to the database using the connect method. After that, you will need a cursor that will operate with that connection. Use the execute method of the cursor to interact with the database, and every once in a while, commit the changes using the comm...
There are two ways to get singleton class of an object singleton_class method. Reopening singleton class of an object and returning self. object.singleton_class singleton_class = class << object self end
Singleton classes share their instance/class variables with their object. class Example @@foo = :example end def Example.foo class_variable_get :@@foo end Example.foo #=> :example class Example def initialize @foo = 1 end def foo @foo end end e = Ex...
For multiple quotechars use regex in place of sep: df = pd.read_csv(log_file, sep=r'\s(?=(?:[^"]*"[^"]*")*[^"]*$)(?![^\[]*\])', engine='python', usecols=[0, 3, 4, 5, 6, 7, 8], names=['ip', 'time', 'request', 'statu...
If you want to change an attribute of a control such as a textbox or label from another thread than the GUI thread that created the control, you will have to invoke it or else you might get an error message stating: "Cross-thread operation not valid: Control 'control_name' accessed from a th...
Let's take a sample class. class Book: def __init__(self, title, author): self.title = title self.author = author book1 = Book(title="Right Ho, Jeeves", author="P.G. Wodehouse") In Python you can access the attribute title of the class using the dot ...
Another useful feature is accessing your custom object collections as arrays in PHP. There are two interfaces available in PHP (>=5.0.0) core to support this: ArrayAccess and Iterator. The former allows you to access your custom objects as array. ArrayAccess Assume we have a user class and a da...
Use a mutex to synchronise access to a variable which is accessed from multiple threads: counter = 0 counter_mutex = Mutex.new # Start three parallel threads and increment counter 3.times.map do |index| Thread.new do counter_mutex.synchronize { counter += 1 } end end.each(&:joi...
String#at Returns a substring of a string object. Same interface as String#[]. str = "hello" str.at(0) # => "h" str.at(1..3) # => "ell" str.at(-2) # => "l" str.at(-2..-1) # => "lo" str.at(5) # => nil str.at(5..-...
The complete sample code for this application (Android + Node server) is available in the PayPal Developer Github repository. From step 2, an async request has been made to our server at the /fpstore endpoint, passing along the auth code and metadata ID. We now need to exchange those for a token in...
Linux running systemd, like Ubuntu 16.04, adding -H tcp://0.0.0.0:2375 to /etc/default/docker does not have the effect it used to. Instead, create a file called /etc/systemd/system/docker-tcp.socket to make docker available on a TCP socket on port 4243: [Unit] Description=Docker Socket for the AP...
It is sometimes required for a process to concurrently write and read the same "data". The ReadWriteLock interface, and its ReentrantReadWriteLock implementation allows for an access pattern that can be described as follow : There can be any number of concurrent readers of the data. If...
When executing a Bash script, parameters passed into the script are named in accordance to their position: $1 is the name of the first parameter, $2 is the name of the second parameter, and so on. A missing parameter simply evaluates to an empty string. Checking for the existence of a parameter can...
In most cases, it is illegal to access an object of one type as though it were a different type (disregarding cv-qualifiers). Example: float x = 42; int y = reinterpret_cast<int&>(x); The result is undefined behavior. There are some exceptions to this strict aliasing rule: An obj...
Here are all access modifiers in venn diagrams, from more limiting to more accessible: Access ModifierDiagramprivateinternalprotectedprotected internalpublic Below you could find more information.
By adding the following extension to array indices can be accessed without knowing if the index is inside bounds. extension Array { subscript (safe index: Int) -> Element? { return indices ~= index ? self[index] : nil } } example: if let thirdValue = array[safe: 2] { ...
# Deny access to a directory from the IP 255.0.0.0 <Directory /path/to/directory> order allow,deny deny from 255.0.0.0 allow from all </Directory> # Deny access to a file from the IP 255.0.0.0 <FilesMatch "^\.ht"> order allow,deny deny fro...
EXC_BAD_ACCESS means the process tried to access memory in an invalid way, like dereferencing a NULL pointer or writing to read-only memory. This is the hardest kind of crash to debug, because it usually does not have an error message, and some crashes can be very difficult to reproduce and/or occu...
You can find description of the driver here. The quick example is: import psycopg2 db_host = 'postgres.server.com' db_port = '5432' db_un = 'user' db_pw = 'password' db_name = 'testdb' conn = psycopg2.connect("dbname={} host={} user={} password={}".format( ...

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