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  • templated method on T inside a templated class on TT : Is that possible/correct.

    - by paercebal
    I have a class MyClass which is templated on typename T. But inside, I want a method which is templated on another type TT (which is unrelated to T). After reading/tinkering, I found the following notation: template <typename T> class MyClass { public : template<typename TT> void MyMethod(const TT & param) ; } ; For stylistic reasons (I like to have my templated class declaration in one header file, and the method definitions in another header file), I won't define the method inside the class declaration. So, I have to write it as: template <typename T> // this is the type of the class template <typename TT> // this is the type of the method void MyClass<T>::MyMethod(const TT & param) { // etc. } I knew I had to "declare" the typenames used in the method, but didn't know how exactly, and found through trials and errors. The code above compiles on Visual C++ 2008, but: Is this the correct way to have a method templated on TT inside a class templated on T? As a bonus: Are there hidden problems/surprises/constraints behind this kind of code? (I guess the specializations can be quite amusing to write)

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  • Can a grails controller extend from a base class? How to make it so grails doesn't blow up?

    - by egervari
    I wrote a base class to help build my controllers more quickly and to remove duplication. It provides some helper methods, default actions and some meta programming to make these things easier to build. One of those methods in the base class is like this: def dynamicList(Class clazz) { def model = new LinkedHashMap() model[getMapString(clazz) + "s"] = list(clazz) model[getMapString(clazz) + "sTotal"] = count(clazz) model } The action that calls it, also in the base class, is this: def list = { dynamicList(clazz) } Unfortunately, when I go to list action in the controller subclass that inherits the base class when my application is deployed, I get this exception: groovy.lang.MissingMethodException: No signature of method: groovy.lang.MissingMethodException.dynamicList() is applicable for argument types: (java.lang.Class) values: [class project .user.User] at project.user.UserController$_closure1.doCall(UserController.groovy:18) at project.user.UserController$_closure1.doCall(UserController.groovy) at java.lang.Thread.run(Thread.java:619) How can I hit grails over the head and just tell it do what I want it to do? My controller unit tests run just fine, so grails' run-time is totally at fault :/ Ken

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  • How to deal with class composition when components cannot be accessed from the outside?

    - by Chathuranga
    For example if I say I have three classes A, B, and C where B and C have a composition relation ship with A. That means the life of B and C is handled by A, and also B and C cannot access directly from the outside. For some reason my DataService class needs to return objects of B and C as It cant return a object of A as B and C cannot be initialized at the same time. (to be able to initializeC you have to initializeB first). So that I'm returning DataTables from DataService and then inside the class A those data tables are converted to B / C objects. If B and C objects cannot be initialized at the same time is it valid to say that B and C have a composition relationship with A? If its composition is it must to generate A with B and C inside? What is the proper way to handle this sort of a problem? EDIT: Following code explains the way I'm doing it now with DataTables. Example: class A { private List<B> B; private List <C> C; public A() { B= new List<B>(); C= new List<C>(); } public List<B> GetB( DataTable dt) { // Create a B list from dt return B; } } class Presenter { private void Show B() { _View.DataGrid = A.GetB(DataService.GetAListOfB()); } } The actual scenario is I have a class called WageInfo and classes Earning and Deduction having a composition relationship in the design. But for you to generate Deductions first you should Generate earnings and should be saved in a table. Then only you can generate deductions for the earnings to calculate balance wages. Also note that these contained classes have a one to many relationship with the containing class WageInfo. So actually WageInfo has a List<Earnings> and List<Deduction> My initial question was, is it ok if my DataService class returns Deductions / Earnings objects (actually lists) not a WageInfo? Still not clear?

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  • How to initialize List<E> in empty class constructor?

    - by Nazgulled
    Hi, The following code obviously doesn't work because List<E> is abstract: public class MyList { private List<E> list; public MyList() { this.list = new List<E>(); } } How can I initialize MyList class with an empty constructor if I need the list variable to be a LinkedList or a ArrayList depending on my needs?

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  • A Reusable Builder Class for .NET testing

    - by Liam McLennan
    When writing tests, other than end-to-end integration tests, we often need to construct test data objects. Of course this can be done using the class’s constructor and manually configuring the object, but to get many objects into a valid state soon becomes a large percentage of the testing effort. After many years of painstakingly creating builders for each of my domain objects I have finally become lazy enough to bother to write a generic, reusable builder class for .NET. To use it you instantiate a instance of the builder and configuring it with a builder method for each class you wish it to be able to build. The builder method should require no parameters and should return a new instance of the type in a default, valid state. In other words the builder method should be a Func<TypeToBeBuilt>. The best way to make this clear is with an example. In my application I have the following domain classes that I want to be able to use in my tests: public class Person { public string Name { get; set; } public int Age { get; set; } public bool IsAndroid { get; set; } } public class Building { public string Street { get; set; } public Person Manager { get; set; } } The builder for this domain is created like so: build = new Builder(); build.Configure(new Dictionary<Type, Func<object>> { {typeof(Building), () => new Building {Street = "Queen St", Manager = build.A<Person>()}}, {typeof(Person), () => new Person {Name = "Eugene", Age = 21}} }); Note how Building depends on Person, even though the person builder method is not defined yet. Now in a test I can retrieve a valid object from the builder: var person = build.A<Person>(); If I need a class in a customised state I can supply an Action<TypeToBeBuilt> to mutate the object post construction: var person = build.A<Person>(p => p.Age = 99); The power and efficiency of this approach becomes apparent when your tests require larger and more complex objects than Person and Building. When I get some time I intend to implement the same functionality in Javascript and Ruby. Here is the full source of the Builder class: public class Builder { private Dictionary<Type, Func<object>> defaults; public void Configure(Dictionary<Type, Func<object>> defaults) { this.defaults = defaults; } public T A<T>() { if (!defaults.ContainsKey(typeof(T))) throw new ArgumentException("No object of type " + typeof(T).Name + " has been configured with the builder."); T o = (T)defaults[typeof(T)](); return o; } public T A<T>(Action<T> customisation) { T o = A<T>(); customisation(o); return o; } }

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  • The design of a generic data synchronizer, or, an [object] that does [actions] with the aid of [helpers]

    - by acheong87
    I'd like to create a generic data-source "synchronizer," where data-source "types" may include MySQL databases, Google Spreadsheets documents, CSV files, among others. I've been trying to figure out how to structure this in terms of classes and interfaces, keeping in mind (what I've read about) composition vs. inheritance and is-a vs. has-a, but each route I go down seems to violate some principle. For simplicity, assume that all data-sources have a header-row-plus-data-rows format. For example, assume that the first rows of Google Spreadsheets documents and CSV files will have column headers, a.k.a. "fields" (to parallel database fields). Also, eventually, I would like to implement this in PHP, but avoiding language-specific discussion would probably be more productive. Here's an overview of what I've tried. Part 1/4: ISyncable class CMySQL implements ISyncable GetFields() // sql query, pdo statement, whatever AddFields() RemFields() ... _dbh class CGoogleSpreadsheets implements ISyncable GetFields() // zend gdata api AddFields() RemFields() ... _spreadsheetKey _worksheetId class CCsvFile implements ISyncable GetFields() // read from buffer AddFields() RemFields() ... _buffer interface ISyncable GetFields() AddFields($field1, $field2, ...) RemFields($field1, $field2, ...) ... CanAddFields() // maybe the spreadsheet is locked for write, or CanRemFields() // maybe no permission to alter a database table ... AddRow() ModRow() RemRow() ... Open() Close() ... First Question: Does it make sense to use an interface, as above? Part 2/4: CSyncer Next, the thing that does the syncing. class CSyncer __construct(ISyncable $A, ISyncable $B) Push() // sync A to B Pull() // sync B to A Sync() // Push() and Pull() only differ in direction; factor. // Sync()'s job is to make sure that the fields on each side // match, to add fields where appropriate and possible, to // account for different column-orderings, etc., and of // course, to add and remove rows as necessary to sync. ... _A _B Second Question: Does it make sense to define such a class, or am I treading dangerously close to the "Kingdom of Nouns"? Part 3/4: CTranslator? ITranslator? Now, here's where I actually get lost, assuming the above is passable. Sometimes, two ISyncables speak different "dialects." For example, believe it or not, Google Spreadsheets (accessed through the Google Data API "list feed") returns column headers lower-cased and stripped of all spaces and symbols! That is, sys_TIMESTAMP is systimestamp, as far as my code can tell. (Yes, I am aware that the "cell feed" does not strip the name so; however cell-by-cell manipulation is too slow for what I'm doing.) One can imagine other hypothetical examples. Perhaps even the data itself can be in different "dialects." But let's take it as given for now, and not argue this if possible. Third Question: How would you implement "translation"? Note: Taking all this as an exercise, I'm more interested in the "idealized" design, rather than the practical one. (God knows that shipped sailed when I began this project.) Part 4/4: Further Thought Here's my train of thought to demonstrate I've thunk, albeit unfruitfully: First, I thought, primitively, "I'll just modify CMySQL::GetFields() to lower-case and strip field names so they're compatible with Google Spreadsheets." But of course, then my class should really be called, CMySQLForGoogleSpreadsheets, and that can't be right. So, the thing which translates must exist outside of an ISyncable implementor. And surely it can't be right to make each translation a method in CSyncer. If it exists outside of both ISyncable and CSyncer, then what is it? (Is it even an "it"?) Is it an abstract class, i.e. abstract CTranslator? Is it an interface, since a translator only does, not has, i.e. interface ITranslator? Does it even require instantiation? e.g. If it's an ITranslator, then should its translation methods be static? (I learned what "late static binding" meant, today.) And, dear God, whatever it is, how should a CSyncer use it? Does it "have" it? Is it, "it"? Who am I? ...am I, "I"? I've attempted to break up the question into sub-questions, but essentially my question is singular: How does one implement an object A that conceptually "links" (has) two objects b1 and b2 that share a common interface B, where certain pairs of b1 and b2 require a helper, e.g. a translator, to be handled by A? Something tells me that I've overcomplicated this design, or violated a principle much higher up. Thank you all very much for your time and any advice you can provide.

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  • Remove Empty Attributes from XML

    - by er4z0r
    Hi, I have a buggy xml that contains empty attributes and I have a parser that coughs on empty attributes. I have no control over the generation of the xml nor over the parser that coughs on empty attrs. So what I want to do is a pre-processing step that simply removes all empty attributes. I have managed to find the empty attribus, but now I don't know how to remove them: XPathFactory xpf = XPathFactory.newInstance(); XPath xpath = xpf.newXPath(); XPathExpression expr = xpath.compile("//@*"); Object result = expr.evaluate(d, XPathConstants.NODESET); if (result != null) { NodeList nodes = (NodeList) result; for(int node=0;node<nodes.getLength();node++) { Node n = nodes.item(node); if(isEmpty(n.getTextContent())) { this.log.warn("Found empty attribute declaration "+n.toString()); NamedNodeMap parentAttrs = n.getParentNode().getAttributes(); parentAttrs.removeNamedItem(n.getNodeName()); } } } This code gives me a NPE when accessing n.getParentNode().getAttributes(). But how can I remove the empty attribute from an element, when I cannot access the element?

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  • PHP & MYSQL: How can i neglect empty variables from select

    - by cash-cash
    hello all; if i have 4 variables and i want to select DISTINCT values form data base <?php $var1 = ""; //this variable can be blank $var2 = ""; //this variable can be blank $var3 = ""; //this variable can be blank $var4 = ""; //this variable can be blank $result = mysql_query("SELECT DISTINCT title,description FROM table WHERE **keywords ='$var1' OR author='$var2' OR date='$var3' OR forums='$var4'** "); ?> note: some or all variables ($var1,$var2,$var3,$var4) can be empty what i want: i want to neglect empty fields lets say that $var1 (keywords) is empty it will select all empty fileds, but i want if $var1 is empty the result will be like $result = mysql_query("SELECT DISTINCT title,description FROM table WHERE author='$var2' OR date='$var3' OR forums='$var4' "); if $var2 is empty the result will be like $result = mysql_query("SELECT DISTINCT title,description FROM table WHERE keywords ='$var1' OR date='$var3' OR forums='$var4' "); if $var1 and $var2 are empty the result will be like $result = mysql_query("SELECT DISTINCT title,description FROM table WHERE date='$var3' OR forums='$var4' "); and so on

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  • c# multi inheritance

    - by user326839
    So ive got a base class which requires a Socket: class Sock { public Socket s; public Sock(Socket s) { this.s = s; } public virtual void Process(byte[] data) { } ... } then ive got another class. if a new socket gets accepted a new instance of this class will be created: class Game : Sock { public Random Random = new Random(); public Timerr Timers; public Test Test; public Game(Socket s) : base(s) { } public static void ReceiveNewSocket(object s) { Game Client = new Game((Socket)s); Client.Start(); } public override void Process(byte[] buf) { Timers = new Timerr(s); Test = new Test(s); Test.T(); } } in the Sock class ive got a virtual function that gets overwritten by the Game class.(Process function) in this function im calling a function from the Test Class(Test+ Timerr Class: class Test : Game { public Test(Socket s) : base(s) { } public void T() { Console.WriteLine(Random.Next(0, 10)); Timers.Start(); } } class Timerr : Game { public Timerr(Socket s) : base(s) { } public void Start() { Console.WriteLine("test"); } } ) So in the Process function im calling a function in Test. And in this function(T) i need to call a function from the Timerr Class.But the problem is its always NULL , although the constructor is called in Process. And e.g. the Random Class can be called, i guess its because its defined with the constructor.: public Random Random = new Random(); and thats why the other classes(without a constructor): public Timerr Timers; public Test Test; are always null in the inherited class Test.But its essentiel that i call other Methods of other classes in this function.How could i solve that?

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  • $_POST data returns empty when headers are > POST_MAX_SIZE

    - by Jared
    Hi Hopefully someone here might have an answer to my question. I have a basic form that contains simple fields, like name, number, email address etc and 1 file upload field. I am trying to add some validation into my script that detects if the file is too large and then rejects the user back to the form to select/upload a smaller file. My problem is, if a user selects a file that is bigger than my validation file size rule and larger than php.ini POST_MAX_SIZE/UPLOAD_MAX_FILESIZE and pushes submit, then PHP seems to try process the form only to fail on the POST_MAX_SIZE settings and then clears the entire $_POST array and returns nothing back to the form. Is there a way around this? Surely if someone uploads something than the max size configured in the php.ini then you can still get the rest of the $_POST data??? Here is my code. <?php function validEmail($email) { $isValid = true; $atIndex = strrpos($email, "@"); if (is_bool($atIndex) && !$atIndex) { $isValid = false; } else { $domain = substr($email, $atIndex+1); $local = substr($email, 0, $atIndex); $localLen = strlen($local); $domainLen = strlen($domain); if ($localLen < 1 || $localLen > 64) { // local part length exceeded $isValid = false; } else if ($domainLen < 1 || $domainLen > 255) { // domain part length exceeded $isValid = false; } else if ($local[0] == '.' || $local[$localLen-1] == '.') { // local part starts or ends with '.' $isValid = false; } else if (preg_match('/\\.\\./', $local)) { // local part has two consecutive dots $isValid = false; } else if (!preg_match('/^[A-Za-z0-9\\-\\.]+$/', $domain)) { // character not valid in domain part $isValid = false; } else if (preg_match('/\\.\\./', $domain)) { // domain part has two consecutive dots $isValid = false; } else if (!preg_match('/^(\\\\.|[A-Za-z0-9!#%&`_=\\/$\'*+?^{}|~.-])+$/', str_replace("\\\\","",$local))) { // character not valid in local part unless // local part is quoted if (!preg_match('/^"(\\\\"|[^"])+"$/', str_replace("\\\\","",$local))) { $isValid = false; } } } return $isValid; } //setup post variables @$name = htmlspecialchars(trim($_REQUEST['name'])); @$emailCheck = htmlspecialchars(trim($_REQUEST['email'])); @$organisation = htmlspecialchars(trim($_REQUEST['organisation'])); @$title = htmlspecialchars(trim($_REQUEST['title'])); @$phone = htmlspecialchars(trim($_REQUEST['phone'])); @$location = htmlspecialchars(trim($_REQUEST['location'])); @$description = htmlspecialchars(trim($_REQUEST['description'])); @$fileError = 0; @$phoneError = ""; //setup file upload handler $target_path = 'uploads/'; $filename = basename( @$_FILES['uploadedfile']['name']); $max_size = 8000000; // maximum file size (8mb in bytes) NB: php.ini max filesize upload is 10MB on test environment. $allowed_filetypes = Array(".pdf", ".doc", ".zip", ".txt", ".xls", ".docx", ".csv", ".rtf"); //put extensions in here that should be uploaded only. $ext = substr($filename, strpos($filename,'.'), strlen($filename)-1); // Get the extension from the filename. if(!is_writable($target_path)) die('You cannot upload to the specified directory, please CHMOD it to 777.'); //Check if we can upload to the specified upload folder. //display form function function displayForm($name, $emailCheck, $organisation, $phone, $title, $location, $description, $phoneError, $allowed_filetypes, $ext, $filename, $fileError) { //make $emailCheck global so function can get value from global scope. global $emailCheck; global $max_size; echo '<form action="geodetic_form.php" method="post" name="contact" id="contact" enctype="multipart/form-data">'."\n". '<fieldset>'."\n".'<div>'."\n"; //name echo '<label for="name"><span class="mandatory">*</span>Your name:</label>'."\n". '<input type="text" name="name" id="name" class="inputText required" value="'. $name .'" />'."\n"; //check if name field is filled out if (isset($_REQUEST['submit']) && empty($name)) { echo '<label for="name" class="error">Please enter your name.</label>'."\n"; } echo '</div>'."\n". '<div>'."\n"; //Email echo '<label for="email"><span class="mandatory">*</span>Your email:</label>'."\n". '<input type="text" name="email" id="email" class="inputText required email" value="'. $emailCheck .'" />'."\n"; // check if email field is filled out and proper format if (isset($_REQUEST['submit']) && validEmail($emailCheck) == false) { echo '<label for="email" class="error">Invalid email address entered.</label>'."\n"; } echo '</div>'."\n". '<div>'."\n"; //organisation echo '<label for="phone">Organisation:</label>'."\n". '<input type="text" name="organisation" id="organisation" class="inputText" value="'. $organisation .'" />'."\n"; echo '</div>'."\n". '</fieldset>'."\n".'<fieldset>'. "\n" . '<div>'."\n"; //title echo '<label for="phone">Title:</label>'."\n". '<input type="text" name="title" id="title" class="inputText" value="'. $title .'" />'."\n"; echo '</div>'."\n". '</fieldset>'."\n".'<fieldset>'. "\n" . '<div>'."\n"; //phone echo '<label for="phone"><span class="mandatory">*</span>Phone <br /><span class="small">(include area code)</span>:</label>'."\n". '<input type="text" name="phone" id="phone" class="inputText required" value="'. $phone .'" />'."\n"; // check if phone field is filled out that it has numbers and not characters if (isset($_REQUEST['submit']) && $phoneError == "true" && empty($phone)) echo '<label for="email" class="error">Please enter a valid phone number.</label>'."\n"; echo '</div>'."\n". '</fieldset>'."\n".'<fieldset>'. "\n" . '<div>'."\n"; //Location echo '<label class="location" for="location"><span class="mandatory">*</span>Location:</label>'."\n". '<textarea name="location" id="location" class="required">'. $location .'</textarea>'."\n"; //check if message field is filled out if (isset($_REQUEST['submit']) && empty($_REQUEST['location'])) echo '<label for="location" class="error">This field is required.</label>'."\n"; echo '</div>'."\n". '</fieldset>'."\n".'<fieldset>'. "\n" . '<div>'."\n"; //description echo '<label class="description" for="description">Description:</label>'."\n". '<textarea name="description" id="queryComments">'. $description .'</textarea>'."\n"; echo '</div>'."\n". '</fieldset>'."\n".'<fieldset>'. "\n" . '<div>'."\n"; //file upload echo '<label class="uploadedfile" for="uploadedfile">File:</label>'."\n". '<input type="file" name="uploadedfile" id="uploadedfile" value="'. $filename .'" />'."\n"; // Check if the filetype is allowed, if not DIE and inform the user. switch ($fileError) { case "1": echo '<label for="uploadedfile" class="error">The file you attempted to upload is not allowed.</label>'; break; case "2": echo '<label for="uploadedfile" class="error">The file you attempted to upload is too large.</label>'; break; } echo '</div>'."\n". '</fieldset>'; //end of form echo '<div class="submit"><input type="submit" name="submit" value="Submit" id="submit" /></div>'. '<div class="clear"><p><br /></p></div>'; } //end function //setup error validations if (isset($_REQUEST['submit']) && !empty($_REQUEST['phone']) && !is_numeric($_REQUEST['phone'])) $phoneError = "true"; if (isset($_REQUEST['submit']) && $_FILES['uploadedfile']['error'] != 4 && !in_array($ext, $allowed_filetypes)) $fileError = 1; if (isset($_REQUEST['submit']) && $_FILES["uploadedfile"]["size"] > $max_size) $fileError = 2; echo "this condition " . $fileError; $POST_MAX_SIZE = ini_get('post_max_size'); $mul = substr($POST_MAX_SIZE, -1); $mul = ($mul == 'M' ? 1048576 : ($mul == 'K' ? 1024 : ($mul == 'G' ? 1073741824 : 1))); if ($_SERVER['CONTENT_LENGTH'] > $mul*(int)$POST_MAX_SIZE && $POST_MAX_SIZE) echo "too big!!"; echo $POST_MAX_SIZE; if(empty($name) || empty($phone) || empty($location) || validEmail($emailCheck) == false || $phoneError == "true" || $fileError != 0) { displayForm($name, $emailCheck, $organisation, $phone, $title, $location, $description, $phoneError, $allowed_filetypes, $ext, $filename, $fileError); echo $fileError; echo "max size is: " .$max_size; echo "and file size is: " . $_FILES["uploadedfile"]["size"]; exit; } else { //copy file from temp to upload directory $path_of_uploaded_file = $target_path . $filename; $tmp_path = $_FILES["uploadedfile"]["tmp_name"]; echo $tmp_path; echo "and file size is: " . filesize($_FILES["uploadedfile"]["tmp_name"]); exit; if(is_uploaded_file($tmp_path)) { if(!copy($tmp_path,$path_of_uploaded_file)) { echo 'error while copying the uploaded file'; } } //test debug stuff echo "sending email..."; exit; } ?> PHP is returning this error in the log: [29-Apr-2010 10:32:47] PHP Warning: POST Content-Length of 57885895 bytes exceeds the limit of 10485760 bytes in Unknown on line 0 Excuse all the debug stuff :) FTR, I am running PHP 5.1.2 on IIS. TIA Jared

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  • Creating an empty Drawable in Android

    - by Kai
    Creating a Drawable that is completely empty seems like a common need, as a place holder, initial state, etc., but there doesn't seem to be a good way to do this... at least in XML. Several places refer to the system resource @android:drawable/empty but as far as I can tell (i.e., it's not in the reference docs, and aapt chokes saying that it can't find the resource) this doesn't exist. Is there a general way of referencing an empty Drawable, or do you end up creating a fake empty PNG for each project?

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  • Python: Why can't I use `super` on a class?

    - by cool-RR
    Why can't I use super to get a method of a class's superclass? Example: Python 3.1.3 >>> class A(object): ... def my_method(self): pass >>> class B(A): ... def my_method(self): pass >>> super(B).my_method Traceback (most recent call last): File "<pyshell#2>", line 1, in <module> super(B).my_method AttributeError: 'super' object has no attribute 'my_method' (Of course this is a trivial case where I could just do A.my_method, but I needed this for a case of diamond-inheritance.) According to super's documentation, it seems like what I want should be possible. This is super's documentation: (Emphasis mine) super() - same as super(__class__, <first argument>) super(type) - unbound super object super(type, obj) - bound super object; requires isinstance(obj, type) super(type, type2) - bound super object; requires issubclass(type2, type) [non-relevant examples redacted]

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  • How do I create a list or set object in a class in Python?

    - by Az
    For my project, the role of the Lecturer (defined as a class) is to offer projects to students. Project itself is also a class. I have some global dictionaries, keyed by the unique numeric id's for lecturers and projects that map to objects. Thus for the "lecturers" dictionary (currently): lecturer[id] = Lecturer(lec_name, lec_id, max_students) I'm currently reading in a white-space delimited text file that has been generated from a database. I have no direct access to the database so I haven't much say on how the file is formatted. Here's a fictionalised snippet that shows how the text file is structured. Please pardon the cheesiness. 0001 001 "Miyamoto, S." "Even Newer Super Mario Bros" 0002 001 "Miyamoto, S." "Legend of Zelda: Skies of Hyrule" 0003 002 "Molyneux, P." "Project Milo" 0004 002 "Molyneux, P." "Fable III" 0005 003 "Blow, J." "Ponytail" The structure of each line is basically proj_id, lec_id, lec_name, proj_name. Now, I'm currently reading the relevant data into the relevant objects. Thus, proj_id is stored in class Project whereas lec_name is a class Lecturer object, et al. The Lecturer and Project classes are not currently related. However, as I read in each line from the text file, for that line, I wish to read in the project offered by the lecturer into the Lecturer class; I'm already reading the proj_id into the Project class. I'd like to create an object in Lecturer called offered_proj which should be a set or list of the projects offered by that lecturer. Thus whenever, for a line, I read in a new project under the same lec_id, offered_proj will be updated with that project. If I wanted to get display a list of projects offered by a lecturer I'd ideally just want to use print lecturers[lec_id].offered_proj. My Python isn't great and I'd appreciate it if someone could show me a way to do that. I'm not sure if it's better as a set or a list, as well. Update After the advice from Alex Martelli and Oddthinking I went back and made some changes and tried to print the results. Here's the code snippet: for line in csv_file: proj_id = int(line[0]) lec_id = int(line[1]) lec_name = line[2] proj_name = line[3] projects[proj_id] = Project(proj_id, proj_name) lecturers[lec_id] = Lecturer(lec_id, lec_name) if lec_id in lecturers.keys(): lecturers[lec_id].offered_proj.add(proj_id) print lec_id, lecturers[lec_id].offered_proj The print lecturers[lec_id].offered_proj line prints the following output: 001 set([0001]) 001 set([0002]) 002 set([0003]) 002 set([0004]) 003 set([0005]) It basically feels like the set is being over-written or somesuch. So if I try to print for a specific lecturer print lec_id, lecturers[001].offered_proj all I get is the last the proj_id that has been read in.

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  • Which should be created first ER Diagram OR Class Diagram?

    - by isthatacode
    The very first step i created a DFD. Then i moved on to create a Class Diagram. And while doing that i felt that i should create the ER diagram first. As there were many details which could not be captured in a Class diagram. So, my question should i create ERD first OR Class Diagrams ? your valuable inputs are appreciated guys!!! thanks for reading

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  • Can can I reference extended methods/params without having to cast from the base class object return

    - by Greg
    Hi, Is there away to not have a "cast" the top.First().Value() return to "Node", but rather have it automatically assume this (as opposed to NodeBase), so I then see extended attributes for the class I define in Node? That is is there a way to say: top.Nodes.First().Value.Path; as opposed to now having to go: ((Node)top.Nodes.First().Value).Path) thanks [TestMethod()] public void CreateNoteTest() { var top = new Topology(); Node node = top.CreateNode("a"); node.Path = "testpath"; Assert.AreEqual("testpath", ((Node)top.Nodes.First().Value).Path); // *** HERE *** } class Topology : TopologyBase<string, Node, Relationship> { } class Node : NodeBase<string> { public string Path { get; set; } } public class NodeBase<T> { public T Key { get; set; } public NodeBase() { } public NodeBase(T key) { Key = key; } } public class TopologyBase<TKey, TNode, TRelationship> where TNode : NodeBase<TKey>, new() where TRelationship : RelationshipBase<TKey>, new() { // Properties public Dictionary<TKey, NodeBase<TKey>> Nodes { get; private set; } public List<RelationshipBase<TKey>> Relationships { get; private set; } }

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  • Accessing constructor from abstract base class with reflection

    - by craesh
    Hi! I'm playing around with Java's Reflection. I have an abstract class Base with a constructor. abstract class Base { public Base( String foo ) { // do some magic } } I have some further classes extending Base. They don't contain much logic. I want to instantiate them with Base's constructor, without having to write some proxy contructors in those derived classes. And of course, I want to instantiate those derived classes with Reflection. Say: Class cls = SomeDerivedClass.class; Constructor constr; constr = cls.getConstructor( new Class[] { String.class } ); // will return null Class clsBase = Base.class; constr = clsBase.getConstructor( new Class[] { String.class } ); // ok Base obj = (Base) constr.newInstance( new Object[] { "foo" } ); // will throw InstantiationException because it belongs to an abstract class Any ideas, how I can instantiate a derived class with Base's constructor? Or must I declare those dumb proxy constructors?

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  • How do I run jQuery form validation by class?

    - by joshcomley
    Hi there, I've been using the jQuery form validator, but I can't seem to figure out how to trigger it by class. Take this example: $("#myform").validate({ rules: { field: { required: true, date: true } } }); Where field it is expecting the name of the particular input. But, what if I have the following: <input class="date".... /> How can I tell the validator to validate all inputs with a "date" class as a date?

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  • What am I not getting about this abstract class implementation?

    - by Schnapple
    PREFACE: I'm relatively inexperienced in C++ so this very well could be a Day 1 n00b question. I'm working on something whose long term goal is to be portable across multiple operating systems. I have the following files: Utilities.h #include <string> class Utilities { public: Utilities() { }; virtual ~Utilities() { }; virtual std::string ParseString(std::string const& RawString) = 0; }; UtilitiesWin.h (for the Windows class/implementation) #include <string> #include "Utilities.h" class UtilitiesWin : public Utilities { public: UtilitiesWin() { }; virtual ~UtilitiesWin() { }; virtual std::string ParseString(std::string const& RawString); }; UtilitiesWin.cpp #include <string> #include "UtilitiesWin.h" std::string UtilitiesWin::ParseString(std::string const& RawString) { // Magic happens here! // I'll put in a line of code to make it seem valid return ""; } So then elsewhere in my code I have this #include <string> #include "Utilities.h" void SomeProgram::SomeMethod() { Utilities *u = new Utilities(); StringData = u->ParseString(StringData); // StringData defined elsewhere } The compiler (Visual Studio 2008) is dying on the instance declaration c:\somepath\somecode.cpp(3) : error C2259: 'Utilities' : cannot instantiate abstract class due to following members: 'std::string Utilities::ParseString(const std::string &)' : is abstract c:\somepath\utilities.h(9) : see declaration of 'Utilities::ParseString' So in this case what I'm wanting to do is use the abstract class (Utilities) like an interface and have it know to go to the implemented version (UtilitiesWin). Obviously I'm doing something wrong but I'm not sure what. It occurs to me as I'm writing this that there's probably a crucial connection between the UtilitiesWin implementation of the Utilities abstract class that I've missed, but I'm not sure where. I mean, the following works #include <string> #include "UtilitiesWin.h" void SomeProgram::SomeMethod() { Utilities *u = new UtilitiesWin(); StringData = u->ParseString(StringData); // StringData defined elsewhere } but it means I'd have to conditionally go through the different versions later (i.e., UtilitiesMac(), UtilitiesLinux(), etc.) What have I missed here?

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  • Python Introspection: How to get varnames of class methods?

    - by daccle
    I want to get the names of the keyword arguments of the methods of a class. I think I understood how to get the names of the methods and how to get the variable names of a specific method, but I don't get how to combine these: class A(object): def A1(self, test1=None): self.test1 = test1 def A2(self, test2=None): self.test2 = test2 def A3(self): pass def A4(self, test4=None, test5=None): self.test4 = test4 self.test5 = test5 a = A() # to get the names of the methods: for methodname in a.__class__.__dict__.keys(): print methodname # to get the variable names of a specific method: for varname in a.A1.__func__.__code__.co_varnames: print varname # I want to have something like this: for function in class: print function.name for varname in function: print varname # desired output: A1 self test1 A2 self test2 A3 self A4 self test4 test5

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  • Is it good to subclass a class only to separate some functional parts?

    - by prostynick
    Suppose we have abstract class A (all examples in C#) public abstract class A { private Foo foo; public A() { } public void DoSomethingUsingFoo() { //stuff } public void DoSomethingElseUsingFoo() { //stuff } //a lot of other stuff... } But we are able to split it into two classes A and B: public abstract class A { public A() { } //a lot of stuff... } public abstract class B : A { private Foo foo; public B() : base() { } public void DoSomethingUsingFoo() { //stuff } public void DoSomethingElseUsingFoo() { //stuff } //nothing else or just some overrides of A stuff } That's good, but we are 99.99% sure, that no one will ever subclass A, because functionality in B is very important. Is it still good to have two separate classes only to split some code into two parts and to separate functional elements?

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  • which should be drawn first , class or sequence diagram?

    - by m0j1
    hi , I've had this discussion with my professor at college about UML diagrams . hi believes that sequence diagrams should be drawn before getting to class diagrams . but I think the opposite . I think after finishing the usecase diagram , the next diagram should be class diagram and after that we should get to sequence diagram . Rational rose requires us to use the classes in sequence diagram, which are already in class diagram . can anyone help me with this? thanks

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  • Differences between a conceptual UML class diagram and an ERD?

    - by Adam
    If I create a conceptual class diagram such that each class captures 'name' and 'attributes' but not 'operations', have I not basically created what would be otherwise considered an ERD? I'm trying to gain an understanding of what the differences are between creating a conceptual class diagram as I have described versus calling it a ERD? If these are still two different animals, can somebody please explain what the differences are?

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  • Meaning of the "Unloading class" messages

    - by elec
    Anyone can explain why the lines below appear in the output console at runtime ? (one possible answer would be full permGen, but this can be ruled out since the program only uses 24MB out of the max100MB available in PermGen) [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor28] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor14] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor4] [Unloading class sun.reflect.GeneratedMethodAccessor5] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor38] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor36] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor22] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor8] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor39] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor16] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor2] [Unloading class sun.reflect.GeneratedConstructorAccessor1] The program runs with the following params: -Xmx160M -XX:MaxPermSize=96M -XX:PermSize=96M -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+PrintGCTaskTimeStamps -XX:+PrintHeapAtGC -XX:+PrintTenuringDistribution -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps -verbose:gc -Xloggc:/logs/gc.log There's plenty of space in the heap and in permGen.

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  • Do I still have to implement a singleton class by hand in .net, even when using .Net4.0?

    - by Hamish Grubijan
    Once the singleton pattern is understood, writing subsequent singleton classes in C# is a brainless exercise. I would hope that the framework would help you by providing an interface or a base class to do that. Here is how I envision it: public sealed class Schablone : ISingleton<Schablone> { // Stuff forced by the interface goes here // Extra logic goes here } Does what I am looking for exist? Is there some syntactic sugar for constructing a singleton class - whether with an interface, a class attribute, etc.? Can one write a useful and bullet-proof ISingleton themselves? Care to try? Thanks!

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