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  • How can I map a String to a function in Java?

    - by Bears will eat you
    Currently, I have a bunch of Java classes that implement a Processor interface, meaning they all have a processRequest(String key) method. The idea is that each class has a few (say, <10) member Strings, and each of those maps to a method in that class via the processRequest method, like so: class FooProcessor implements Processor { String key1 = "abc"; String key2 = "def"; String key3 = "ghi"; // and so on... String processRequest(String key) { String toReturn = null; if (key1.equals(key)) toReturn = method1(); else if (key2.equals(key)) toReturn = method2(); else if (key3.equals(key)) toReturn = method3(); // and so on... return toReturn; } String method1() { // do stuff } String method2() { // do other stuff } String method3() { // do other other stuff } // and so on... } You get the idea. This was working fine for me, but now I need a runtime-accessible mapping from key to function; not every function actually returns a String (some return void) and I need to dynamically access the return type (using reflection) of each function in each class that there's a key for. I already have a manager that knows about all the keys, but not the mapping from key to function. My first instinct was to replace this mapping using if-else statements with a Map<String, Function>, like I could do in Javascript. But, Java doesn't support first-class functions so I'm out of luck there. I could probably dig up a third-party library that lets me work with first-class functions, but I haven't seen any yet, and I doubt that I need an entire new library. I also thought of putting these String keys into an array and using reflection to invoke the methods by name, but I see two downsides to this method: My keys would have to be named the same as the method - or be named in a particular, consistent way so that it's easy to map them to the method name. This seems WAY slower than the if-else statements I have right now. Efficiency is something of a concern because these methods will tend to get called pretty frequently, and I want to minimize unnecessary overhead. TL; DR: I'm looking for a clean, minimal-overhead way to map a String to some sort of a Function object that I can invoke and call (something like) getReturnType() on. I don't especially mind using a 3rd-party library if it really fits my needs. I also don't mind using reflection, though I would strongly prefer to avoid using reflection every single time I do a method lookup - maybe using some caching strategy that combines the Map with reflection. Thoughts on a good way to get what I want? Cheers!

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  • lua - how to call function from above it in code (prior to it being defined)?

    - by Greg
    what is the syntax (i.e. code example) in Lua so you can call a function prior to it being defined? i.e. how do you kind of create the function, but then add it's implementation further down in code. So roughly like this: define function name (doX) here somehow (i.e. subject of this question) call doX here (further down in the code) doX implemention here (i.e. all functions down at the bottom of the file)

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  • Does a native php (5+) function exist that does the following in 1 line?

    - by Vinh
    function array_value_from_key($array,$key) { return !empty($array[$key]) ? $array[$key] : null; } The reason I ask is because I have a class function that returns an array. Instead of having to do $myArray = myClass::giveMeArray(); $myValue = $myArray[$myKey]; I'd like to do something along the lines of $myValue = array_value_from_key(myClass::giveMeArray(),$myKey); When an object is returned, you can chain the object such as $myValue = myClass::giveMeObject()->aValue; Voila, nice and clean.. not being able to find what seems to be a simple and trivial function is driving me crazy... PS.. one more example of how I'd like to use such a function if(arrayKeyVal(aClass::giveMeArray(),$myKey)) { do_something(); }

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  • Javascript: can I call a function in an external file from the main page ?

    - by Patrick
    hi, I'm loading from my main page an external js file, with a function. I have a flash file in the main page invoking the javascript function. Everything worked very well until when the javascript code was in the main file, but when I moved javascript to an external file the function seems not called anymore. So... there is no way to move the javascript code to an external file ? Or any other solution ? thanks

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  • scala coalesces multiple function call parameters into a Tuple -- can this be disabled?

    - by landon9720
    This is a troublesome violation of type safety in my project, so I'm looking for a way to disable it. It seems that if a function takes an AnyRef (or a java.lang.Object), you can call the function with any combination of parameters, and Scala will coalesce the parameters into a Tuple object and invoke the function. In my case the function isn't expecting a Tuple, and fails at runtime. I would expect this situation to be caught at compile time. object WhyTuple { def main(args: Array[String]): Unit = { fooIt("foo", "bar") } def fooIt(o: AnyRef) { println(o.toString) } } Output: (foo,bar)

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  • [javascript] Can I overload an object with a function?

    - by user257493
    Lets say I have an object of functions/values. I'm interested in overloading based on calling behavior. For example, this block of code below demonstrates what I wish to do. var main_thing = { initalized: false, something: "Hallo, welt!", something_else: [123,456,789], load: { sub1 : function() { //Some stuff }, sub2 : function() { //Some stuff }, all : function() { this.load.sub1(); this.load.sub2(); } } init: function () { this.initalized=true; this.something="Hello, world!"; this.something_else = [0,0,0]; this.load(); //I want this to call this.load.all() instead. } } The issue to me is that main_thing.load is assigned to an object, and to call main_thing.load.all() would call the function inside of the object (the () operator). What can I do to set up my code so I could use main_thing.load as an access the object, and main_thing.load() to execute some code? Or at least, similar behavior. Basically, this would be similar to a default constructor in other languages where you don't need to call main_thing.constructor(). If this isn't possible, please explain with a bit of detail.

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  • Python - 2 Questions: Editing a variable in a function and changing the order of if else statements

    - by Eric
    First of all, I should explain what I'm trying to do first. I'm creating a dungeon crawler-like game, and I'm trying to program the movement of computer characters/monsters in the map. The map is basically a Cartesian coordinate grid. The locations of characters are represented by tuples of the x and y values, (x,y). The game works by turns, and in a turn a character can only move up, down, left or right 1 space. I'm creating a very simple movement system where the character will simply make decisions to move on a turn by turn basis. Essentially a 'forgetful' movement system. A basic flow chart of what I'm intending to do: Find direction towards destination Make a priority list of movements to be done using the direction eg.('r','u','d','l') means it would try to move right first, then up, then down, then left. Try each of the possibilities following the priority order. If the first movement fails (blocked by obstacle etc.), then it would successively try the movements until the first one that is successful, then it would stop. At step 3, the way I'm trying to do it is like this: def move(direction,location): try: -snip- # Tries to move, raises the exception Movementerror if cannot move in the direction return 1 # Indicates movement successful except Movementerror: return 0 # Indicates movement unsuccessful (thus character has not moved yet) prioritylist = ('r','u','d','l') if move('r',location): pass elif move('u',location): pass elif move('d',location): pass elif move('l',location): pass else: pass In the if/else block, the program would try the first movement on the priority on the priority list. At the move function, the character would try to move. If the character is not blocked and does move, it returns 1, leading to the pass where it would stop. If the character is blocked, it returns 0, then it tries the next movement. However, this results in 2 problems: How do I edit a variable passed into a function inside the function itself, while returning if the edit is successful? I have been told that you can't edit a variable inside a function as it won't really change the value of the variable, it just makes the variable inside the function refer to something else while the original variable remain unchanged. So, the solution is to return the value and then assign the variable to the returned value. However, I want it to return another value indicating if this edit is successful, so I want to edit this variable inside the function itself. How do I do so? How do I change the order of the if/else statements to follow the order of the priority list? It needs to be able to change during runtime as the priority list can change resulting in a different order of movement to try.

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  • Registration form validation not validating

    - by jgray
    I am a noob when it comes to web development. I am trying to validate a registration form and to me it looks right but it will not validate.. This is what i have so far and i am validating through a repository or database. Any help would be greatly appreciated. thanks <?php session_start(); $title = "User Registration"; $keywords = "Name, contact, phone, e-mail, registration"; $description = "user registration becoming a member."; require "partials/_html_header.php"; //require "partials/_header.php"; require "partials/_menu.php"; require "DataRepository.php"; // if all validation passed save user $db = new DataRepository(); // form validation goes here $first_nameErr = $emailErr = $passwordErr = $passwordConfirmErr = ""; $first_name = $last_name = $email = $password = $passwordConfirm = ""; if(isset($_POST['submit'])) { $valid = TRUE; // check if all fields are valid { if ($_SERVER["REQUEST_METHOD"] == "POST") { if (empty($_POST["first_name"])) {$first_nameErr = "Name is required";} else { // $first_name = test_input($_POST["first_name"]); // check if name only contains letters and whitespace if (!preg_match("/^[a-zA-Z ]*$/",$first_name)) { $first_nameErr = "Only letters and white space allowed"; } } if (empty($_POST["email"])) {$emailErr = "Email is required";} else { // $email = test_input($_POST["email"]); // check if e-mail address syntax is valid if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email)) { $emailErr = "Invalid email format"; } } if (!preg_match("/(......)/",$password)) { $passwordErr = "Subject must contain THREE or more characters!"; } if ($_POST['password']!= $_POST['passwordConfirm']) { echo("Oops! Password did not match! Try again. "); } function test_input($data) { $data = trim($data); $data = stripslashes($data); $data = htmlspecialchars($data); return $data; } } } if(!$db->isEmailUnique($_POST['email'])) { $valid = FALSE; //display errors in the correct places } // if still valid save the user if($valid) { $new_user = array( 'first_name' => $_POST['first_name'], 'last_name' => $_POST['last_name'], 'email' => $_POST['email'], 'password' => $_POST['password'] ); $results = $db->saveUser($new_user); if($results == TRUE) { header("Location: login.php"); } else { echo "WTF!"; exit; } } } ?> <head> <style> .error {color: #FF0000;} </style> </head> <h1 class="center"> World Wide Web Creations' User Registration </h1> <p><span class="error"></span><p> <form method="POST" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>" onsubmit="return validate_form()" > First Name: <input type="text" name="first_name" id="first_name" value="<?php echo $first_name;?>" /> <span class="error"> <?php echo $first_nameErr;?></span> <br /> <br /> Last Name(Optional): <input type="text" name="last_name" id="last_name" value="<?php echo $last_name;?>" /> <br /> <br /> E-mail: <input type="email" name="email" id="email" value="<?php echo $email;?>" /> <span class="error"> <?php echo $emailErr;?></span> <br /> <br /> Password: <input type="password" name="password" id="password" value="" /> <span class="error"> <?php echo $passwordErr;?></span> <br /> <br /> Confirmation Password: <input type="password" name="passwordConfirm" id="passwordConfirm" value="" /> <span class="error"> <?php echo $passwordConfirmErr;?></span> <br /> <br /> <br /> <br /> <input type="submit" name="submit" id="submit" value="Submit Data" /> <input type="reset" name="reset" id="reset" value="Reset Form" /> </form> </body> </html> <?php require "partials/_footer.php"; require "partials/_html_footer.php"; ?> class DataRepository { // version number private $version = "1.0.3"; // turn on and off debugging private static $debug = FALSE; // flag to (re)initialize db on each call private static $initialize_db = FALSE; // insert test data on initialization private static $load_default_data = TRUE; const DATAFILE = "203data.txt"; private $data = NULL; private $errors = array(); private $user_fields = array( 'id' => array('required' => 0), 'created_at' => array('required' => 0), 'updated_at' => array('required' => 0), 'first_name' => array('required' => 1), 'last_name' => array('required' => 0), 'email' => array('required' => 1), 'password' => array('required' => 1), 'level' => array('required' => 0, 'default' => 2), ); private $post_fields = array( 'id' => array('required' => 0), 'created_at' => array('required' => 0), 'updated_at' => array('required' => 0), 'user_id' => array('required' => 1), 'title' => array('required' => 1), 'message' => array('required' => 1), 'private' => array('required' => 0, 'default' => 0), ); private $default_user = array( 'id' => 1, 'created_at' => '2013-01-01 00:00:00', 'updated_at' => '2013-01-01 00:00:00', 'first_name' => 'Admin Joe', 'last_name' => 'Tester', 'email' => '[email protected]', 'password' => 'a94a8fe5ccb19ba61c4c0873d391e987982fbbd3', 'level' => 1, ); private $default_post = array( 'id' => 1, 'created_at' => '2013-01-01 00:00:00', 'updated_at' => '2013-01-01 00:00:00', 'user_id' => 1, 'title' => 'My First Post', 'message' => 'This is the message of the first post.', 'private' => 0, ); // constructor will load existing data into memory // if it does not exist it will create it and initialize if desired public function __construct() { // check if need to reset if(DataRepository::$initialize_db AND file_exists(DataRepository::DATAFILE)) { unlink(DataRepository::DATAFILE); } // if file doesn't exist, create the initial datafile if(!file_exists(DataRepository::DATAFILE)) { $this->log("Data file does not exist. Attempting to create it... (".__FUNCTION__.":".__LINE__.")"); // create initial file $this->data = array( 'users' => array( ), 'posts' => array() ); // load default data if needed if(DataRepository::$load_default_data) { $this->data['users'][1] = $this->default_user; $this->data['posts'][1] = $this->default_post; } $this->writeTheData(); } // load the data into memory for use $this->loadTheData(); } private function showErrors($break = TRUE, $type = NULL) { if(count($this->errors) > 0) { echo "<div style=\"color:red;font-weight: bold;font-size: 1.3em\":<h3>$type Errors</h3><ol>"; foreach($this->errors AS $error) { echo "<li>$error</li>"; } echo "</ol></div>"; if($break) { "</br></br></br>Exiting because of errors!"; exit; } } } private function writeTheData() { $this->log("Attempting to write the datafile: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); file_put_contents(DataRepository::DATAFILE, json_encode($this->data)); $this->log("Datafile written: ".DataRepository::DATAFILE." (line: ".__LINE__.")"); } private function loadTheData() { $this->log("Attempting to load the datafile: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); $this->data = json_decode(file_get_contents(DataRepository::DATAFILE), true); $this->log("Datafile loaded: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $this->data); } private function validateFields(&$info, $fields, $pre_errors = NULL) { // merge in any pre_errors if($pre_errors != NULL) { $this->errors = array_merge($this->errors, $pre_errors); } // check all required fields foreach($fields AS $field => $reqs) { if(isset($reqs['required']) AND $reqs['required'] == 1) { if(!isset($info[$field]) OR strlen($info[$field]) == 0) { $this->errors[] = "$field is a REQUIRED field"; } } // set any default values if not present if(isset($reqs['default']) AND (!isset($info[$field]) OR $info[$field] == "")) { $info[$field] = $reqs['default']; } } $this->showErrors(); if(count($this->errors) == 0) { return TRUE; } else { return FALSE; } } private function validateUser(&$user_info) { // check if the email is already in use $this->log("About to check pre_errors: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $user_info); $pre_errors = NULL; if(isset($user_info['email'])) { if(!$this->isEmailUnique($user_info['email'])) { $pre_errors = array('The email: '.$user_info['email'].' is already used in our system'); } } $this->log("After pre_error check: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $pre_errors); return $this->validateFields($user_info, $this->user_fields, $pre_errors); } private function validatePost(&$post_info) { // check if the user_id in the post actually exists $this->log("About to check pre_errors: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $post_info); $pre_errors = NULL; if(isset($post_info['user_id'])) { if(!isset($this->data['users'][$post_info['user_id']])) { $pre_errors = array('The posts must belong to a valid user. (User '.$post_info['user_id'].' does not exist in the data'); } } $this->log("After pre_error check: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $pre_errors); return $this->validateFields($post_info, $this->post_fields, $pre_errors); } private function log($message, $data = NULL) { $style = "background-color: #F8F8F8; border: 1px solid #DDDDDD; border-radius: 3px; font-size: 13px; line-height: 19px; overflow: auto; padding: 6px 10px;"; if(DataRepository::$debug) { if($data != NULL) { $dump = "<div style=\"$style\"><pre>".json_encode($data, JSON_PRETTY_PRINT)."</pre></div>"; } else { $dump = NULL; } echo "<code><b>Debug:</b> $message</code>$dump<br />"; } } public function saveUser($user_info) { $this->log("Entering saveUser: (".__FUNCTION__.":".__LINE__.")", $user_info); $mydata = array(); $update = FALSE; // check for existing data if(isset($user_info['id']) AND $this->data['users'][$user_info['id']]) { $mydata = $this->data['users'][$user_info['id']]; $this->log("Loaded prior user: ".print_r($mydata, TRUE)." (".__FUNCTION__.":".__LINE__.")"); } // copy over existing values $this->log("Before copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); foreach($user_info AS $k => $v) { $mydata[$k] = $user_info[$k]; } $this->log("After copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); // check required fields if($this->validateUser($mydata)) { // hash password if new if(isset($mydata['password'])) { $mydata['password'] = sha1($mydata['password']); } // if no id, add the next available one if(!isset($mydata['id']) OR (int)$mydata['id'] < 1) { $this->log("No id set: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); if(count($this->data['users']) == 0) { $mydata['id'] = 1; $this->log("Setting id to 1: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } else { $mydata['id'] = max(array_keys($this->data['users']))+1; $this->log("Found max id and added 1 [".$mydata['id']."]: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } } // set created date if null if(!isset($mydata['created_at'])) { $mydata['created_at'] = date ("Y-m-d H:i:s", time()); } // update modified time $mydata['modified_at'] = date ("Y-m-d H:i:s", time()); // copy into data and save $this->log("Before data save: (".__FUNCTION__.":".__LINE__.")", $this->data); $this->data['users'][$mydata['id']] = $mydata; $this->writeTheData(); } return TRUE; } public function getUserById($id) { if(isset($this->data['users'][$id])) { return $this->data['users'][$id]; } else { return array(); } } public function isEmailUnique($email) { // find the user that has the right username/password foreach($this->data['users'] AS $k => $v) { $this->log("Checking unique email: {$v['email']} == $email (".__FUNCTION__.":".__LINE__.")", NULL); if($v['email'] == $email) { $this->log("FOUND NOT unique email: {$v['email']} == $email (".__FUNCTION__.":".__LINE__.")", NULL); return FALSE; break; } } $this->log("Email IS unique: $email (".__FUNCTION__.":".__LINE__.")", NULL); return TRUE; } public function login($username, $password) { // hash password for validation $password = sha1($password); $this->log("Attempting to login with $username / $password: (".__FUNCTION__.":".__LINE__.")", NULL); $user = NULL; // find the user that has the right username/password foreach($this->data['users'] AS $k => $v) { if($v['email'] == $username AND $v['password'] == $password) { $user = $v; break; } } $this->log("Exiting login: (".__FUNCTION__.":".__LINE__.")", $user); return $user; } public function savePost($post_info) { $this->log("Entering savePost: (".__FUNCTION__.":".__LINE__.")", $post_info); $mydata = array(); // check for existing data if(isset($post_info['id']) AND $this->data['posts'][$post_info['id']]) { $mydata = $this->data['posts'][$post_info['id']]; $this->log("Loaded prior posts: ".print_r($mydata, TRUE)." (".__FUNCTION__.":".__LINE__.")"); } $this->log("Before copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); foreach($post_info AS $k => $v) { $mydata[$k] = $post_info[$k]; } $this->log("After copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); // check required fields if($this->validatePost($mydata)) { // if no id, add the next available one if(!isset($mydata['id']) OR (int)$mydata['id'] < 1) { $this->log("No id set: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); if(count($this->data['posts']) == 0) { $mydata['id'] = 1; $this->log("Setting id to 1: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } else { $mydata['id'] = max(array_keys($this->data['posts']))+1; $this->log("Found max id and added 1 [".$mydata['id']."]: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } } // set created date if null if(!isset($mydata['created_at'])) { $mydata['created_at'] = date ("Y-m-d H:i:s", time()); } // update modified time $mydata['modified_at'] = date ("Y-m-d H:i:s", time()); // copy into data and save $this->data['posts'][$mydata['id']] = $mydata; $this->log("Before data save: (".__FUNCTION__.":".__LINE__.")", $this->data); $this->writeTheData(); } return TRUE; } public function getAllPosts() { return $this->loadPostsUsers($this->data['posts']); } public function loadPostsUsers($posts) { foreach($posts AS $id => $post) { $posts[$id]['user'] = $this->getUserById($post['user_id']); } return $posts; } public function dump($line_number, $temp = 'NO') { // if(DataRepository::$debug) { if($temp == 'NO') { $temp = $this->data; } echo "<pre>Dumping from line: $line_number\n"; echo json_encode($temp, JSON_PRETTY_PRINT); echo "</pre>"; } } } /* * Change Log * * 1.0.0 * - first version * 1.0.1 * - Added isEmailUnique() function for form validation and precheck on user save * 1.0.2 * - Fixed getAllPosts() to include the post's user info * - Added loadPostsUsers() to load one or more posts with their user info * 1.0.3 * - Added autoload to always add admin Joe. */

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  • How can I bind the second argument in a function but not the first (in an elegant way)?

    - by Frank Osterfeld
    Is there a way in Haskell to bind the second argument but not the first of a function without using lambda functions or defining another "local" function? Example. I have a binary function like: sub :: Int -> Int -> Int sub x y = x - y Now if I want to bind the first argument, I can do so easily using (sub someExpression): mapSubFrom5 x = map (sub 5) x *Main> mapSubFrom5 [1,2,3,4,5] [4,3,2,1,0] That works fine if I want to bind the first n arguments without "gap". If I want to bind the second argument but not the first, the two options I am aware of are more verbose: Either via another, local, function: mapSub5 x = map sub5 x where sub5 x = sub x 5 *Main> mapSub5 [1,2,3,4,5] [-4,-3,-2,-1,0] Or using lambda: mapSub5 x = map (\x -> sub x 5) x While both are working fine, I like the elegance of "sub 5" and wonder if there is a similarly elegant way to bind the n-th (n 1) argument of a function?

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  • How can I get returned value from JavaScript function that contain jQuery.get() ?

    - by Space Cracker
    I have a JavaScript method that call JQuery.get() and i want to return value from itto callee function .. the following is the code : function CheckExistance(userName) { $.get( "JQueryPage.aspx", { name: userName }, function(result) { if (result == "1") { value = true; } else if (result == "0") { value = false; } else if (result == "error") { value = false; } } ); return value; } i want return value; return the value setted in get() function ... i know that get() is asynchronous operation anf i want a solution to do that ?

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  • Which function should i use for testin if a var isset or not?

    - by streetparade
    I'm sometimes confused to using which one of them, say i have a function called getmember($id) function getmember($id) { // now this is the confusing part // how do i test if a $id was set or not set? //solution 1 if(empty($id)) { return false; } // solution 2 if(isset($id)) { return false; } } Thats sometimes not clear tome some times if a parameter in a function is set like function($var="") Then i do if($var ==="") { return false; } What should i use the next time isset ? emtyp ? or ===''

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  • Accessing current class through $this-> from a function called statically. [PHP]

    - by MQA
    This feels a bit messy, but I'd like to be able to call a member function statically, yet have the rest of the class behave normally... Example: <?php class Email { private $username = 'user'; private $password = 'password'; private $from = '[email protected]'; public $to; public function SendMsg($to, $body) { if (isset($this)) $email &= $this; else $email = new Email(); $email->to = $to; // Rest of function... } } Email::SendMsg('[email protected]'); How best do I allow the static function call in this example? Thanks!

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  • MySQL Syslog Audit Plugin

    - by jonathonc
    This post shows the construction process of the Syslog Audit plugin that was presented at MySQL Connect 2012. It is based on an environment that has the appropriate development tools enabled including gcc,g++ and cmake. It also assumes you have downloaded the MySQL source code (5.5.16 or higher) and have compiled and installed the system into the /usr/local/mysql directory ready for use.  The information provided below is designed to show the different components that make up a plugin, and specifically an audit type plugin, and how it comes together to be used within the MySQL service. The MySQL Reference Manual contains information regarding the plugin API and how it can be used, so please refer there for more detailed information. The code in this post is designed to give the simplest information necessary, so handling every return code, managing race conditions etc is not part of this example code. Let's start by looking at the most basic implementation of our plugin code as seen below: /*    Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.    Author:  Jonathon Coombes    Licence: GPL    Description: An auditing plugin that logs to syslog and                 can adjust the loglevel via the system variables. */ #include <stdio.h> #include <string.h> #include <mysql/plugin_audit.h> #include <syslog.h> There is a commented header detailing copyright/licencing and meta-data information and then the include headers. The two important include statements for our plugin are the syslog.h plugin, which gives us the structures for syslog, and the plugin_audit.h include which has details regarding the audit specific plugin api. Note that we do not need to include the general plugin header plugin.h, as this is done within the plugin_audit.h file already. To implement our plugin within the current implementation we need to add it into our source code and compile. > cd /usr/local/src/mysql-5.5.28/plugin > mkdir audit_syslog > cd audit_syslog A simple CMakeLists.txt file is created to manage the plugin compilation: MYSQL_ADD_PLUGIN(audit_syslog audit_syslog.cc MODULE_ONLY) Run the cmake  command at the top level of the source and then you can compile the plugin using the 'make' command. This results in a compiled audit_syslog.so library, but currently it is not much use to MySQL as there is no level of api defined to communicate with the MySQL service. Now we need to define the general plugin structure that enables MySQL to recognise the library as a plugin and be able to install/uninstall it and have it show up in the system. The structure is defined in the plugin.h file in the MySQL source code.  /*   Plugin library descriptor */ mysql_declare_plugin(audit_syslog) {   MYSQL_AUDIT_PLUGIN,           /* plugin type                    */   &audit_syslog_descriptor,     /* descriptor handle               */   "audit_syslog",               /* plugin name                     */   "Author Name",                /* author                          */   "Simple Syslog Audit",        /* description                     */   PLUGIN_LICENSE_GPL,           /* licence                         */   audit_syslog_init,            /* init function     */   audit_syslog_deinit,          /* deinit function */   0x0001,                       /* plugin version                  */   NULL,                         /* status variables        */   NULL,                         /* system variables                */   NULL,                         /* no reserves                     */   0,                            /* no flags                        */ } mysql_declare_plugin_end; The general plugin descriptor above is standard for all plugin types in MySQL. The plugin type is defined along with the init/deinit functions and interface methods into the system for sharing information, and various other metadata information. The descriptors have an internally recognised version number so that plugins can be matched against the api on the running server. The other details are usually related to the type-specific methods and structures to implement the plugin. Each plugin has a type-specific descriptor as well which details how the plugin is implemented for the specific purpose of that plugin type. /*   Plugin type-specific descriptor */ static struct st_mysql_audit audit_syslog_descriptor= {   MYSQL_AUDIT_INTERFACE_VERSION,                        /* interface version    */   NULL,                                                 /* release_thd function */   audit_syslog_notify,                                  /* notify function      */   { (unsigned long) MYSQL_AUDIT_GENERAL_CLASSMASK |                     MYSQL_AUDIT_CONNECTION_CLASSMASK }  /* class mask           */ }; In this particular case, the release_thd function has not been defined as it is not required. The important method for auditing is the notify function which is activated when an event occurs on the system. The notify function is designed to activate on an event and the implementation will determine how it is handled. For the audit_syslog plugin, the use of the syslog feature sends all events to the syslog for recording. The class mask allows us to determine what type of events are being seen by the notify function. There are currently two major types of event: 1. General Events: This includes general logging, errors, status and result type events. This is the main one for tracking the queries and operations on the database. 2. Connection Events: This group is based around user logins. It monitors connections and disconnections, but also if somebody changes user while connected. With most audit plugins, the principle behind the plugin is to track changes to the system over time and counters can be an important part of this process. The next step is to define and initialise the counters that are used to track the events in the service. There are 3 counters defined in total for our plugin - the # of general events, the # of connection events and the total number of events.  static volatile int total_number_of_calls; /* Count MYSQL_AUDIT_GENERAL_CLASS event instances */ static volatile int number_of_calls_general; /* Count MYSQL_AUDIT_CONNECTION_CLASS event instances */ static volatile int number_of_calls_connection; The init and deinit functions for the plugin are there to be called when the plugin is activated and when it is terminated. These offer the best option to initialise the counters for our plugin: /*  Initialize the plugin at server start or plugin installation. */ static int audit_syslog_init(void *arg __attribute__((unused))) {     openlog("mysql_audit:",LOG_PID|LOG_PERROR|LOG_CONS,LOG_USER);     total_number_of_calls= 0;     number_of_calls_general= 0;     number_of_calls_connection= 0;     return(0); } The init function does a call to openlog to initialise the syslog functionality. The parameters are the service to log under ("mysql_audit" in this case), the syslog flags and the facility for the logging. Then each of the counters are initialised to zero and a success is returned. If the init function is not defined, it will return success by default. /*  Terminate the plugin at server shutdown or plugin deinstallation. */ static int audit_syslog_deinit(void *arg __attribute__((unused))) {     closelog();     return(0); } The deinit function will simply close our syslog connection and return success. Note that the syslog functionality is part of the glibc libraries and does not require any external factors.  The function names are what we define in the general plugin structure, so these have to match otherwise there will be errors. The next step is to implement the event notifier function that was defined in the type specific descriptor (audit_syslog_descriptor) which is audit_syslog_notify. /* Event notifier function */ static void audit_syslog_notify(MYSQL_THD thd __attribute__((unused)), unsigned int event_class, const void *event) { total_number_of_calls++; if (event_class == MYSQL_AUDIT_GENERAL_CLASS) { const struct mysql_event_general *event_general= (const struct mysql_event_general *) event; number_of_calls_general++; syslog(audit_loglevel,"%lu: User: %s Command: %s Query: %s\n", event_general->general_thread_id, event_general->general_user, event_general->general_command, event_general->general_query ); } else if (event_class == MYSQL_AUDIT_CONNECTION_CLASS) { const struct mysql_event_connection *event_connection= (const struct mysql_event_connection *) event; number_of_calls_connection++; syslog(audit_loglevel,"%lu: User: %s@%s[%s] Event: %d Status: %d\n", event_connection->thread_id, event_connection->user, event_connection->host, event_connection->ip, event_connection->event_subclass, event_connection->status ); } }   In the case of an event, the notifier function is called. The first step is to increment the total number of events that have occurred in our database.The event argument is then cast into the appropriate event structure depending on the class type, of general event or connection event. The event type counters are incremented and details are sent via the syslog() function out to the system log. There are going to be different line formats and information returned since the general events have different data compared to the connection events, even though some of the details overlap, for example, user, thread id, host etc. On compiling the code now, there should be no errors and the resulting audit_syslog.so can be loaded into the server and ready to use. Log into the server and type: mysql> INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so'; This will install the plugin and will start updating the syslog immediately. Note that the audit plugin attaches to the immediate thread and cannot be uninstalled while that thread is active. This means that you cannot run the UNISTALL command until you log into a different connection (thread) on the server. Once the plugin is loaded, the system log will show output such as the following: Oct  8 15:33:21 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: (null)  Query: INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so' Oct  8 15:33:21 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: Query  Query: INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so' Oct  8 15:33:40 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: (null)  Query: show tables Oct  8 15:33:40 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: Query  Query: show tables Oct  8 15:33:43 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: (null)  Query: select * from t1 Oct  8 15:33:43 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: Query  Query: select * from t1 It appears that two of each event is being shown, but in actuality, these are two separate event types - the result event and the status event. This could be refined further by changing the audit_syslog_notify function to handle the different event sub-types in a different manner.  So far, it seems that the logging is working with events showing up in the syslog output. The issue now is that the counters created earlier to track the number of events by type are not accessible when the plugin is being run. Instead there needs to be a way to expose the plugin specific information to the service and vice versa. This could be done via the information_schema plugin api, but for something as simple as counters, the obvious choice is the system status variables. This is done using the standard structure and the declaration: /*  Plugin status variables for SHOW STATUS */ static struct st_mysql_show_var audit_syslog_status[]= {   { "Audit_syslog_total_calls",     (char *) &total_number_of_calls,     SHOW_INT },   { "Audit_syslog_general_events",     (char *) &number_of_calls_general,     SHOW_INT },   { "Audit_syslog_connection_events",     (char *) &number_of_calls_connection,     SHOW_INT },   { 0, 0, SHOW_INT } };   The structure is simply the name that will be displaying in the mysql service, the address of the associated variables, and the data type being used for the counter. It is finished with a blank structure to show that there are no more variables. Remember that status variables may have the same name for variables from other plugin, so it is considered appropriate to add the plugin name at the start of the status variable name to avoid confusion. Looking at the status variables in the mysql client shows something like the following: mysql> show global status like "audit%"; +--------------------------------+-------+ | Variable_name                  | Value | +--------------------------------+-------+ | Audit_syslog_connection_events | 1     | | Audit_syslog_general_events    | 2     | | Audit_syslog_total_calls       | 3     | +--------------------------------+-------+ 3 rows in set (0.00 sec) The final connectivity piece for the plugin is to allow the interactive change of the logging level between the plugin and the system. This requires the ability to send changes via the mysql service through to the plugin. This is done using the system variables interface and defining a single variable to keep track of the active logging level for the facility. /* Plugin system variables for SHOW VARIABLES */ static MYSQL_SYSVAR_STR(loglevel, audit_loglevel,                         PLUGIN_VAR_RQCMDARG,                         "User can specify the log level for auditing",                         audit_loglevel_check, audit_loglevel_update, "LOG_NOTICE"); static struct st_mysql_sys_var* audit_syslog_sysvars[] = {     MYSQL_SYSVAR(loglevel),     NULL }; So now the system variable 'loglevel' is defined for the plugin and associated to the global variable 'audit_loglevel'. The check or validation function is defined to make sure that no garbage values are attempted in the update of the variable. The update function is used to save the new value to the variable. Note that the audit_syslog_sysvars structure is defined in the general plugin descriptor to associate the link between the plugin and the system and how much they interact. Next comes the implementation of the validation function and the update function for the system variable. It is worth noting that if you have a simple numeric such as integers for the variable types, the validate function is often not required as MySQL will handle the automatic check and validation of simple types. /* longest valid value */ #define MAX_LOGLEVEL_SIZE 100 /* hold the valid values */ static const char *possible_modes[]= { "LOG_ERROR", "LOG_WARNING", "LOG_NOTICE", NULL };  static int audit_loglevel_check(     THD*                        thd,    /*!< in: thread handle */     struct st_mysql_sys_var*    var,    /*!< in: pointer to system                                         variable */     void*                       save,   /*!< out: immediate result                                         for update function */     struct st_mysql_value*      value)  /*!< in: incoming string */ {     char buff[MAX_LOGLEVEL_SIZE];     const char *str;     const char **found;     int length;     length= sizeof(buff);     if (!(str= value->val_str(value, buff, &length)))         return 1;     /*         We need to return a pointer to a locally allocated value in "save".         Here we pick to search for the supplied value in an global array of         constant strings and return a pointer to one of them.         The other possiblity is to use the thd_alloc() function to allocate         a thread local buffer instead of the global constants.     */     for (found= possible_modes; *found; found++)     {         if (!strcmp(*found, str))         {             *(const char**)save= *found;             return 0;         }     }     return 1; } The validation function is simply to take the value being passed in via the SET GLOBAL VARIABLE command and check if it is one of the pre-defined values allowed  in our possible_values array. If it is found to be valid, then the value is assigned to the save variable ready for passing through to the update function. static void audit_loglevel_update(     THD*                        thd,        /*!< in: thread handle */     struct st_mysql_sys_var*    var,        /*!< in: system variable                                             being altered */     void*                       var_ptr,    /*!< out: pointer to                                             dynamic variable */     const void*                 save)       /*!< in: pointer to                                             temporary storage */ {     /* assign the new value so that the server can read it */     *(char **) var_ptr= *(char **) save;     /* assign the new value to the internal variable */     audit_loglevel= *(char **) save; } Since all the validation has been done already, the update function is quite simple for this plugin. The first part is to update the system variable pointer so that the server can read the value. The second part is to update our own global plugin variable for tracking the value. Notice that the save variable is passed in as a void type to allow handling of various data types, so it must be cast to the appropriate data type when assigning it to the variables. Looking at how the latest changes affect the usage of the plugin and the interaction within the server shows: mysql> show global variables like "audit%"; +-----------------------+------------+ | Variable_name         | Value      | +-----------------------+------------+ | audit_syslog_loglevel | LOG_NOTICE | +-----------------------+------------+ 1 row in set (0.00 sec) mysql> set global audit_syslog_loglevel="LOG_ERROR"; Query OK, 0 rows affected (0.00 sec) mysql> show global status like "audit%"; +--------------------------------+-------+ | Variable_name                  | Value | +--------------------------------+-------+ | Audit_syslog_connection_events | 1     | | Audit_syslog_general_events    | 11    | | Audit_syslog_total_calls       | 12    | +--------------------------------+-------+ 3 rows in set (0.00 sec) mysql> show global variables like "audit%"; +-----------------------+-----------+ | Variable_name         | Value     | +-----------------------+-----------+ | audit_syslog_loglevel | LOG_ERROR | +-----------------------+-----------+ 1 row in set (0.00 sec)   So now we have a plugin that will audit the events on the system and log the details to the system log. It allows for interaction to see the number of different events within the server details and provides a mechanism to change the logging level interactively via the standard system methods of the SET command. A more complex auditing plugin may have more detailed code, but each of the above areas is what will be involved and simply expanded on to add more functionality. With the above skeleton code, it is now possible to create your own audit plugins to implement your own auditing requirements. If, however, you are not of the coding persuasion, then you could always consider the option of the MySQL Enterprise Audit plugin that is available to purchase.

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  • How can I accept the agreement for ttf-mscorefonts-installer?

    - by Magic
    After a recent update, ttf-mscorefonts-installer prompted me to accept its license agreement. For some reason my terminal will not allow me to accept, or for some reason I am pressing the wrong hotkey... I've tried every letter on the keyboard and Enter among others... I'm sure there is a very simple and obvious solution to this. I've also just tried to remove the package completely however the terminal states that due to the package not being correctly installed, I should reinstall the package before removing it. Very frustrating! Essentially, because I cannot successfully install this package, I can't really ever upgrade my system because I always have to end up terminating the terminal with the license agreement (thus the upgrade fails).

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  • Monitoring Html Element CSS Changes in JavaScript

    - by Rick Strahl
    [ updated Feb 15, 2011: Added event unbinding to avoid unintended recursion ] Here's a scenario I've run into on a few occasions: I need to be able to monitor certain CSS properties on an HTML element and know when that CSS element changes. For example, I have a some HTML element behavior plugins like a drop shadow that attaches to any HTML element, but I then need to be able to automatically keep the shadow in sync with the window if the  element dragged around the window or moved via code. Unfortunately there's no move event for HTML elements so you can't tell when it's location changes. So I've been looking around for some way to keep track of the element and a specific CSS property, but no luck. I suspect there's nothing native to do this so the only way I could think of is to use a timer and poll rather frequently for the property. I ended up with a generic jQuery plugin that looks like this: (function($){ $.fn.watch = function (props, func, interval, id) { /// <summary> /// Allows you to monitor changes in a specific /// CSS property of an element by polling the value. /// when the value changes a function is called. /// The function called is called in the context /// of the selected element (ie. this) /// </summary> /// <param name="prop" type="String">CSS Properties to watch sep. by commas</param> /// <param name="func" type="Function"> /// Function called when the value has changed. /// </param> /// <param name="interval" type="Number"> /// Optional interval for browsers that don't support DOMAttrModified or propertychange events. /// Determines the interval used for setInterval calls. /// </param> /// <param name="id" type="String">A unique ID that identifies this watch instance on this element</param> /// <returns type="jQuery" /> if (!interval) interval = 200; if (!id) id = "_watcher"; return this.each(function () { var _t = this; var el$ = $(this); var fnc = function () { __watcher.call(_t, id) }; var itId = null; var data = { id: id, props: props.split(","), func: func, vals: [props.split(",").length], fnc: fnc, origProps: props, interval: interval }; $.each(data.props, function (i) { data.vals[i] = el$.css(data.props[i]); }); el$.data(id, data); hookChange(el$, id, data.fnc); }); function hookChange(el$, id, fnc) { el$.each(function () { var el = $(this); if (typeof (el.get(0).onpropertychange) == "object") el.bind("propertychange." + id, fnc); else if ($.browser.mozilla) el.bind("DOMAttrModified." + id, fnc); else itId = setInterval(fnc, interval); }); } function __watcher(id) { var el$ = $(this); var w = el$.data(id); if (!w) return; var _t = this; if (!w.func) return; // must unbind or else unwanted recursion may occur el$.unwatch(id); var changed = false; var i = 0; for (i; i < w.props.length; i++) { var newVal = el$.css(w.props[i]); if (w.vals[i] != newVal) { w.vals[i] = newVal; changed = true; break; } } if (changed) w.func.call(_t, w, i); // rebind event hookChange(el$, id, w.fnc); } } $.fn.unwatch = function (id) { this.each(function () { var el = $(this); var fnc = el.data(id).fnc; try { if (typeof (this.onpropertychange) == "object") el.unbind("propertychange." + id, fnc); else if ($.browser.mozilla) el.unbind("DOMAttrModified." + id, fnc); else clearInterval(id); } // ignore if element was already unbound catch (e) { } }); return this; } })(jQuery); With this I can now monitor movement by monitoring say the top CSS property of the element. The following code creates a box and uses the draggable (jquery.ui) plugin and a couple of custom plugins that center and create a shadow. Here's how I can set this up with the watcher: $("#box") .draggable() .centerInClient() .shadow() .watch("top", function() { $(this).shadow(); },70,"_shadow"); ... $("#box") .unwatch("_shadow") .shadow("remove"); This code basically sets up the window to be draggable and initially centered and then a shadow is added. The .watch() call then assigns a CSS property to monitor (top in this case) and a function to call in response. The component now sets up a setInterval call and keeps on pinging this property every time. When the top value changes the supplied function is called. While this works and I can now drag my window around with the shadow following suit it's not perfect by a long shot. The shadow move is delayed and so drags behind the window, but using a higher timer value is not appropriate either as the UI starts getting jumpy if the timer's set with too small of an increment. This sort of monitor can be useful for other things as well where operations are maybe not quite as time critical as a UI operation taking place. Can anybody see a better a better way of capturing movement of an element on the page?© Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  JavaScript  jQuery  

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  • Multiple domain with one host - SEO pov

    - by Swing Magic
    Lets say i currently have mycompanyname.com domain. and after several time i found that its very hard to hit top of serp. after searching i find there is domain that match with one of my keyword. i build website with 2 language. and im able to assign both of url with different language. my question, impact with SEO? it will have a load of duplicated content between those domain (image video etc). im afraid one of my website will have marked as plagiarist because many of content will be same. anyone experience the same condition? Thank you!

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  • C# Threading Background Process - Programming - How to?

    - by Magic
    Hello...I have been given the horrible task of doing this. Launch the website Take a screenshot Fill in the form details, click on Next Take a screenshot ... ... ... Rinse. Repeat. Now, with various combinations, this comes up to 300 screenshots. And I have to do this for 4 different browsers. Chrome, Firefox, IE 6 and IE 7. I cannot use tools which will capture the screenshot and store them, such as, SnagIT. I need to take a screenshot, copy it to a Word Document and take the second screenshot and take it to a Word Document. I thought, I will write a tiny utility which will help me do this. Here is the requirement spec that I put up for it - An executable which once launched seats itself in the System Tray. While it is active, all instances of Key Press (Print Scrn), it should write the contents to a Word Document as defined (either a default path or a user defined one). Save the document periodically. Now, my question is - if I am going to develop this using C# (Winforms application), how do I go about doing this. I can do a fair bit of C# programming and I am willing to learn. But I am not able to locate the references for how to do a background process so that it runs in the background. And while it runs, it has to capture the Print Scrn command. Can you folks point me to the right material where I can learn this? Theoretical references should suffice. But if there are practical references, then nothing like it. Thanks!

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