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• tips for fixing bad coding/dev habits ?

  - by dfafa

  i want to become a better coder....so i have decided to sign up for computing science program...maybe a formal education can assist me. i started working on smaller projects to learn but currently i have really bad coding/dev habits which is hindering my productivity as the codebase increases.... i have highlighted them and perhaps someone could make suggestions (or redirect to resources) or a more efficient method. most stuff that i made in the past were web apps. i usually develop with putty + nano...i just love the minimalist feel i use winscp and develop directly on my private web server...too lazy to do it on localhost and upload it later. i dont use subversion control...which one do i need ? sometimes ctrl +z doesn't work well. when i run out of ideas for naming variable, i use swear words instead. i swear a lot when i get stuck....how to deal with anger issue ? my codes look ugly with comments everywhere. would rather use procedural coding finds "thinking" in OO difficult and time consuming i "write first think later". refactors code only if i am getting paid for it. dislikes configuring linux distro, Apache, MySQL, scaling, designing graphics and layouts. does not like writing tests likes working alone. does not like sharing codes. has an econ degree dislikes reading other people's code would rather write it on my own it seems my only true desire is to translate my ideas to a working prototype as fast as possible....it seems like i am very uninterested in the other details...could it be that i am not cut out to be a coder after all ? is going back to study comp sci a bad idea ?

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• Inheritance of closure objects and overriding of methods

  - by bobikk

  I need to extend a class, which is encapsulated in a closure. This base class is following: var PageController = (function(){ // private static variable var _current_view; return function(request, new_view) { ... // priveleged public function, which has access to the _current_view this.execute = function() { alert("PageController::execute"); } } })(); Inheritance is realised using the following function: function extend(subClass, superClass){ var F = function(){ }; F.prototype = superClass.prototype; subClass.prototype = new F(); subClass.prototype.constructor = subClass; subClass.superclass = superClass.prototype; StartController.cache = ''; if (superClass.prototype.constructor == Object.prototype.constructor) { superClass.prototype.constructor = superClass; } } I subclass the PageController: var StartController = function(request){ // calling the constructor of the super class StartController.superclass.constructor.call(this, request, 'start-view'); } // extending the objects extend(StartController, PageController); // overriding the PageController::execute StartController.prototype.execute = function() { alert('StartController::execute'); } Inheritance is working. I can call every PageController's method from StartController's instance. However, method overriding doesn't work: var startCont = new StartController(); startCont.execute(); alerts "PageController::execute". How should I override this method?

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• What is the Proper approach for Constructing a PhysicalAddress object from Byte Array

  - by Paul Farry

  I'm trying to understand what the correct approach for a constructor that accepts a Byte Array with regard to how it stores it's data (specifically with PhysicalAddress) I have an array of 6 bytes (theAddress) that is constructed once. I have a source array of 18bytes (theAddresses) that is loaded from a TCP Connection. I then copy the 6bytes from theAddress+offset into theAddress and construct the PhysicalAddress from it. Problem is that the PhysicalAddress just stores the Reference to the array that was passed in. Therefore if you subsequently check the addresses they only ever point to the last address that was copied in. When I took a look inside the PhysicalAddress with reflector it's easy to see what's going on. public PhysicalAddress(byte[] address) { this.changed = true; this.address = address; } Now I know this can be solved by creating theAddress array on each pass, but I wanted to find out what really is the best practice for this. Should the constructor of an object that accepts a byte array create it's own private Variable for holding the data and copy it from the original Should it just hold the reference to what was passed in. Should I just created theAddress on each pass in the loop

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• Read XML with PHP

  - by sea_1987

  I am trying to check a field in some XML that is returned from an outside. The XML is returned in a variable call $out and when you view the source of the page you get a XML output of the following, <?xml version="1.0" encoding="UTF-8"?> <ResponseBlock Live="FALSE" Version="3.51"> <Response Type="AUTH"> <OperationResponse> <TransactionReference>23-9-1334895</TransactionReference> <TransactionCompletedTimestamp>2010-04-30 15:59:05</TransactionCompletedTimestamp> <AuthCode>AUTH CODE:TEST</AuthCode> <TransactionVerifier>AlaUOS1MOnN/iwc5s2WPDm5ggrCLwesUnHs9h+W0N3CRaln2W6lh+6dtaRFFhLdwfnw6y7lRemyJUYl9a3dpWfzORE6DaZkFMb+dIb0Ne1UxjFEJkrEtjzx/i8KSayrIBrT/yGZOoOT42EZ9loc+UkdGk/pqYvj8bZztvgBNo2Ak=</TransactionVerifier> <Result>1</Result> <SettleStatus>0</SettleStatus> <SecurityResponseSecurityCode>1</SecurityResponseSecurityCode> <SecurityResponsePostCode>1</SecurityResponsePostCode> <SecurityResponseAddress>1</SecurityResponseAddress> </OperationResponse> <Order> <OrderInformation>This is a test order</OrderInformation> <OrderReference>Order0001</OrderReference> </Order> </Response> </ResponseBlock> I want check what value is in the 'Result' field. I am unsure how to access the information using PHP, so far I have, $xml = simplexml_load_string($out); Many Thanks

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• In Ruby, why does a method invocation not be able to be treated as a unit when "do" and "end" is use

  - by Jian Lin

  The following question is related to http://stackoverflow.com/questions/2127836/ruby-print-inject-do-syntax The question is, can we insist on using DO and END and make it work with puts or p? This works: a = [1,2,3,4] b = a.inject do |sum, x| sum + x end puts b # prints out 10 so, is it correct to say, inject is a class method of the Array class, which takes a block of code, and then returns a number. If so, then it should be no different from calling a function and getting back a return value: b = foo(3) puts b or b = circle.getRadius() puts b In the above two cases, we can directly say puts foo(3) puts circle.getRadius() so, there is no way to make it work directly by using the following 2 ways: a = [1,2,3,4] puts a.inject do |sum, x| sum + x end but it gives ch01q2.rb:7:in `inject': no block given (LocalJumpError) from ch01q2.rb:4:in `each' from ch01q2.rb:4:in `inject' from ch01q2.rb:4 grouping the method call using ( ) doesn't work either: a = [1,2,3,4] puts (a.inject do |sum, x| sum + x end) and this gives: ch01q3.rb:4: syntax error, unexpected kDO_BLOCK, expecting ')' puts (a.inject do |sum, x| ^ ch01q3.rb:4: syntax error, unexpected '|', expecting '=' puts (a.inject do |sum, x| ^ ch01q3.rb:6: syntax error, unexpected kEND, expecting $end end) ^ finally, the following version works: a = [1,2,3,4] puts a.inject { |sum, x| sum + x } but why doesn't the grouping of the method invocation using ( ) work? What if a programmer insists that he uses do and end, can it be made to work directly with p or puts, without an extra temporary variable?

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• Having an issue with org.hibernate.SessionException: Session is closed! in Hibernate

  - by hal10001

  I've done quite a bit a research on this with no luck, but all the answers have a tendency to point toward the session context settings in the config file. What is odd is that I get a session connection the very first time I hit the page (and therefore, a successful result set), but then when I reload I get the following exception: org.hibernate.SessionException: Session is closed! Here are my config settings that are not DB connection string related: <property name="hibernate.show_sql">false</property> <property name="hibernate.dialect">org.hibernate.dialect.SQLServerDialect</property> <property name="hibernate.current_session_context_class">thread</property> <property name="hibernate.cache.provider_class">org.hibernate.cache.NoCacheProvider</property> <property name="hibernate.cache.use_query_cache">false</property> <property name="hibernate.cache.use_minimal_puts">false</property> Here is an example of a call I make that produces the situation I described above. public T get(int id) { session.beginTransaction(); T type; try { type = getTypeClass().cast(session.get(getTypeClass(), id)); } catch (ClassCastException classCastException) { throw new ClassCastException(classCastException.getMessage()); } session.getTransaction().commit(); return type; } The session variable reference is to a static field that contains the current session. All of the session connection details are textbook reference manual. For example, here is my Hibernate session utility: import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class HibernateSessionFactoryUtil { private static final SessionFactory sessionFactory = buildSessionFactory(); private static SessionFactory buildSessionFactory() { try { return new Configuration().configure().buildSessionFactory(); } catch (Throwable ex) { System.err.println("Initial SessionFactory creation failed." + ex); throw new ExceptionInInitializerError(ex); } } public static SessionFactory getSessionFactory() { return sessionFactory; } }

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• Insert HTML on Radio Label on Formtastic

  - by Adrian Matteo

  I have a form that has a radio button on it (Formtastic), and It works just fine with the :collection I'm passing. The problem is I want some part of the text to be affected by some CSS, but the :collection attribute does not let me put in HTML. Here's my code: = subscription.input :plan_type_id, :as => :radio, :label => false, :wrapper_html => {:class => "plan_type"}, :collection => { @plans[:premium_yearly][:description]+number_to_currency(@plans[:premium_yearly][:amount], :precision => 2) => @plans[:premium_yearly][:value], @plans[:premium_monthly][:description]+number_to_currency(@plans[:premium_monthly][:amount], :precision => 2) => @plans[:premium_monthly][:value] } Has you may may see, I build the label I want to show with my @plans variable and the :collection attribute. Is there any way I can modify the way it renders the label, I want to put some css to some part of the label. I want something like this: = subscription.input :plan_type_id, :as => :radio, :label => false, :wrapper_html => {:class => "plan_type"}, :collection => { @plans[:premium_yearly][:description]+'<b>'+number_to_currency(@plans[:premium_yearly][:amount], :precision => 2)+'<\\b>' => @plans[:premium_yearly][:value], @plans[:premium_monthly][:description]+'<b>'+number_to_currency(@plans[:premium_monthly][:amount], :precision => 2)+'<\\b>' => @plans[:premium_monthly][:value] } Thanks in advanced.

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• Making a jQuery plugin to feed Tumblr to site

  - by tylorreimer

  I have some experience with PHP and a little with JS but I'm far from anything proficient. I'm trying to make a jQuery plugin for my site that I can call in my HTML via something like this: $('.new').tumble({username: "tylor", count: 9}); Which would basically put the Tumblr list the code should make into the DIV with class 'new' in this case. Here is my code so far; the problem seems to be how to get it to pick up class/id from the original call (in the HTML) and use that in the jQuery. Here's the code so far: (function($) { $.fn.tumble = function(options){ var settings = $.extend({ username: null, // [string or array] required to get url for tumblr account count: 3, // [integer] how many posts to display? }, options); //url construction var url = "http://" + settings.username + ".tumblr.com"; var jsonurl = url + "/api/read/json?num=" + settings.count + "&callback=?"; $.getJSON(jsonurl, function(data) { var items = []; $.each(data.posts, function(id, url) { // Goes over each post in the JSON document retrieved from data URL var url = this.url; // Just assigns a variable to the url to avoid constantly writing "this.whatever" var photourl = this['photo-url-250']; // photo-url-xxx needs to be called this way due to integers in the name items.push('<li><a href="' + url + '">' + photourl + '</a></li>'); }); $('<ul/>', { // Creates an empty list html: items.join('') // Takes the values in the item array and puts 'em together }).appendTo('.new'); // I don't want this to have the class set in the jQuery itself }); //end json }; })( jQuery ); Any help you can lend would be wonderful. Thank you

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• Confused as to use a class or a function: Writing XML files using lxml and Python

  - by PulpFiction

  Hi. I need to write XML files using lxml and Python. However, I can't figure out whether to use a class to do this or a function. The point being, this is the first time I am developing a proper software and deciding where and why to use a class still seems mysterious. I will illustrate my point. For example, consider the following function based code I wrote for adding a subelement to a etree root. from lxml import etree root = etree.Element('document') def createSubElement(text, tagText = ""): etree.SubElement(root, text) # How do I do this: element.text = tagText createSubElement('firstChild') createSubElement('SecondChild') As expected, the output of this is: <document> <firstChild/> <SecondChild/> </document> However as you can notice the comment, I have no idea how to do set the text variable using this approach. Is using a class the only way to solve this? And if yes, can you give me some pointers on how to achieve this?

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• Have I taken a wrong path in programming by being excessively worried about code elegance and style?

  - by Ygam

  I am in a major stump right now. I am a BSIT graduate, but I only started actual programming less than a year ago. I observed that I have the following attitude in programming: I tend to be more of a purist, scorning unelegant approaches to solving problems using code I tend to look at anything in a large scale, planning everything before I start coding, either in simple flowcharts or complex UML charts I have a really strong impulse on refactoring my code, even if I miss deadlines or prolong development times I am obsessed with good directory structures, file naming conventions, class, method, and variable naming conventions I tend to always want to study something new, even, as I said, at the cost of missing deadlines I tend to see software development as something to engineer, to architect; that is, seeing how things relate to each other and how blocks of code can interact (I am a huge fan of loose coupling) i.e the OOP thinking I tend to combine OOP and procedural coding whenever I see fit I want my code to execute fast (thus the elegant approaches and refactoring) This bothers me because I see my colleagues doing much better the other way around (aside from the fact that they started programming since our first year in college). By the other way around I mean, they fire up coding, gets the job done much faster because they don't have to really look at how clean their codes are or how elegant their algorithms are, they don't bother with OOP however big their projects are, they mostly use web APIs, piece them together and voila! Working code! CLients are happy, they get paid fast, at the expense of a really unmaintainable or hard-to-read code that lacks structure and conventions, or slow executions of certain actions (which the common reasoning against would be that internet connections are much faster these days, hardware is more powerful). The excuse I often receive is clients don't care about how you write the code, but they do care about how long you deliver it. If it works then all is good. Now, did my "purist" approach to programming may have been the wrong way to start programming? Should I just dump these purist concepts and just code the hell up because I have seen it: clients don't really care how beautifully coded it is?

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• How to make Web Storage persistent in Cordova using JS?

  - by ett

  I have a small quiz app, which is a cross-platform mobile app, that I plan for it to run on Android, iOS, and WP8. I want to store a local highscore, where it will keep track how many points the user had, and if he/she does better than the already stored highscore, update the current highscore. Though, I want the highscore to be persistent, what I mean is, every time the user opens the app I want the last highscore to be present and it to be compared with the new quiz score. Meaning, I don't want the highscore to be deleted after each time the app is closed. I also want for the first time when the app is ran, the highscore to be set to 0, so obviously the first time the user finishes the quiz gets a new highscore. I have those codes so far: scoredb.js // Wait for device API libraries to load document.addEventListener("deviceready", initScoreDB, false); // Device APIs are available function initScoreDB() { window.localStorage.setItem("score", 0); highscore = window.localStorage.getItem("score"); } main.js var correct = 0; var highscore; // In between I have some code that keeps incrementing // correct variable for each correct answer. if (correct > highscore) { window.localStorage.setItem("score", correct); highscore = correct; } It does seem to work okay once the app is started. I did the quiz three times, in the simulator, and it keeps the score as it should. Though, each time I open the app, highscore is reseted to 0. I guess it is due to the fact that I call initScoreDB when the device is ready, and I initialize the score to 0 there and give that value to highscore. Can someone help me to initialize the score to 0 only when the app is ran for the first time, and all the other times to keep the latest highscore as the current highscore and compare it each time with the score that is achieved when the quiz is finished. If someone can help me, I would be glad.

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• How can I set up an editor to work with Git on Windows?

  - by Patrick McElhaney

  I'm trying out Git on Windows. I got to the point of trying "git commit" and I got this error: Terminal is dumb but no VISUAL nor EDITOR defined. Please supply the message using either -m or -F option. So I figured out I need to have an environment variable called EDITOR. No problem. I set it to point to Notepad. That worked, almost. The default commit message opens in Notepad. But Notepad doesn't support bare line feeds. I went out and got Notepad++. But I can't figure out how to get Notepad++ set up as the %EDITOR% in such a way that it works with Git as expected. I'm not married to Notepad++. At this point I couldn't care less what editor I use. I just want to be able to type my commit messages without using -m. So, for those of you using Git on Windows: What (free) tool do you use to edit your commit message, and what do you get when you type echo %EDITOR% at the command prompt?

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• Applying policy based design question

  - by Arthur

  I've not read the Modern C++ Design book but have found the idea of behavior injection through templates interesting. I am now trying to apply it myself. I have a class that has a logger that I thought could be injected as a policy. The logger has a log() method which takes an std::string or std::wstring depending on its policy: // basic_logger.hpp template<class String> class basic_logger { public: typedef String string_type; void log(const string_type & s) { ... } }; typedef basic_logger<std::string> logger; typedef basic_logger<std::wstring> wlogger; // reader.hpp template<class Logger = logger> class reader { public: typedef Logger logger_type; void read() { _logger.log("Reading..."); } private: logger_type _logger; }; Now the questing is, should the reader take a Logger as an argument, like above, or should it take a String and then instantiate a basic_logger as an instance variable? Like so: template<class String> class reader { public: typedef String string_type; typedef basic_logger<string_type> logger_type; // ... private: logger_type _logger; }; What is the right way to go?

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• class header+ implementation

  - by igor

  what am I doing wrong here? I keep on getting a compilation error when I try to run this in codelab (turings craft) Instructions: Write the implementation (.cpp file) of the GasTank class of the previous exercise. The full specification of the class is: A data member named amount of type double. A constructor that no parameters. The constructor initializes the data member amount to 0. A function named addGas that accepts a parameter of type double . The value of the amount instance variable is increased by the value of the parameter. A function named useGas that accepts a parameter of type double . The value of the amount data member is decreased by the value of the parameter. A function named getGasLevel that accepts no parameters. getGasLevel returns the value of the amount data member. class GasTank{ double amount; GasTank(); void addGas(double); void useGas(double); double getGasLevel();}; GasTank::GasTank(){ amount=0;} double GasTank::addGas(double a){ amount+=a;} double GasTank::useGas(double a){ amount+=a;} double GasTank::getGasLevel(){ return amount;}

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• property names are different from original Object in the silverlight

  - by kwon

  Following is part of service layer which is provided by WCF service : [Serializable] public class WaitInfo { private string roomName; private string pName; private string tagNo; public string RoomName { get { return roomName; } set { this.roomName = value; } } public string PName { get { return pName; } set { this.pName = value; } } public string TagNo { get { return tagNo; } set { this.tagNo = value; } } } public class Service1 : IService1 { public List<WaitInfo> GetWaitingList() { MyDBDataContext db = new MyDBDataContext(); var query = from w in db.WAIT_INFOs select new WaitInfo { TagNo = w.PATIENT_INFO.TAG_NO, RoomName= w.ROOM_INFO.ROOM_NAME, PName= w.PATIENT_INFO.P_NAME }; List<WaitInfo> result = query.ToList(); return result; } And following is codebehind part of UI layer which is provided by Silverlight public MainPage() { InitializeComponent(); Service1Client s = new Service1Client(); s.GetWaitingListCompleted += new EventHandler<GetWaitingListByCompletedEventArgs>( s_GetWaitingListCompleted); s.GetWaitingListAsync(); } void s_GetWaitingListCompleted(object sender, RadControlsSilverlightApplication1.ServiceReference2.GetWaitingListByCompletedEventArgs e) { GridDataGrid.ItemsSource = e.Result; } And following is xaml code in Silverlight page <Grid x:Name="LayoutRoot"> <data:DataGrid x:Name="GridDataGrid"></data:DataGrid> </Grid> Is is very simple code, however what I am thinking weird is property name of object at "e.Result" in the code behind page. In the service layer, although properties' names are surely "RoomName, PName, TagNo", in the silverlight properties' names are "roomName, pName, tagNo" which are private variable name of the WaitingList Object. Did I something wrong? Thanks in advance.

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• Java generic Comparable where subclasses can't compare to eachother

  - by dege

  public abstract class MyAbs implements Comparable<MyAbs> This would work but then I would be able to compare class A and B with each other if they both extend MyAbs. What I want to accomplish however is the exact opposite. So does anyone know a way to get the generic type to be the own class? Seemed like such a simple thing at first... Edit: To explain it a little further with an example. Say you have an abstract class animals, then you extend it with Dogs and ants. I wouldn't want to compare ants with Dogs but I however would want to compare one dog with another. The dog might have a variable saying what color it is and that is what I want to use in the compareTo method. However when it comes to ants I would rather want to compare ant's size than their color. Hope that clears it up. Could possibly be a design flaw however.

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• Iterating XML nodes using VBA

  - by ydobonmai

  Note:- It just might be a iterating XML nodes using VBA question. Please look at the bottom of this question. It would be good If we can iterate without using MSXML2.DOMDocument I see the this question which answers part of my question on how to retrieve the CustomXMLPart. However, I am not able to iterate through the Xml. That way, this might not be specific to CustomXmlPart, It just might be a iterating XML using VBA question. Following is the XML I have in my CustomXMLPart. <Items> <Item1>Item1</Item1> <Item2>Item2</Item2> <Item3>Item3</Item3> </Items> This is how I add the above XML as CustomXmlPart:- static void AddCustomTableXmlPart(WordprocessingDocument document) { MainDocumentPart mainDocumentPart = document.MainDocumentPart; XDocument itemXml = GetItemsAsCustomXML(); if (mainDocumentPart.GetPartsCountOfType<CustomXmlPart>() > 0) mainDocumentPart.DeleteParts<CustomXmlPart>(mainDocumentPart.CustomXmlParts); //Add a new customXML part and then add content var customXmlPart = mainDocumentPart.AddCustomXmlPart(CustomXmlPartType.CustomXml); //copy the XML into the new part... using (var ts = new StreamWriter(customXmlPart.GetStream())) { ts.Write(itemXml.ToString()); ts.Flush(); } } and this is how I am accessing it in the macro:- Dim itemNode As xmlNode Dim itemChildren As XMLNodes ' The below line throws a run-time error 'Run-time error '13' - 'type mismatch ' not sure why. **Set itemChildren= ActiveDocument.CustomXMLParts(ActiveDocument.CustomXMLParts.Count).SelectSingleNode("//Items").ChildNodes** Interestingly, when I quick watch ActiveDocument.CustomXMLParts(ActiveDocument.CustomXMLParts.Count).SelectSingleNode("//Items").ChildNodes, I see child items in the quick watch window. Is the assignment to the itemChildren variable incorrect? I want to iterate through all the items and get get text for all of them. Could anybody help?

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• VS2010 Implement Generic Interface expansion doesn't use specified type

  - by TJB

  Using the release version of Visual Studio 2010 I think there's a difference in the "Implement Interface" expansion from VS2008 If I speicify an interface and implement it in a class as so: public interface IRepository<T> where T : IModel { T Get<T>(int id); void Update<T>(); int Add<T>(T item); } public class MockRepository : IRepository<MockUser> { // ... } Then use the "Implement Interface" expansion and get this: public class MockRepository : IRepository<MockUser> { public T Get<T>(int id) { throw new NotImplementedException(); } public void Update<T>() { throw new NotImplementedException(); } public int Add<T>(T item) { throw new NotImplementedException(); } } Instead of what I expected public class MockRepository : IRepository<MockUser> { public MockUser Get<MockUser>(int id) { throw new NotImplementedException(); } public void Update<MockUser>() { throw new NotImplementedException(); } public int Add<MockUser>(MockUser item) { throw new NotImplementedException(); } } The IDE uses the type variable name from the generic interface definition T instead of the specified concrete type MockUser. Is this a bug? Or is something new just for VS2010 / .Net 4.0?

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• How to parse text as JavaScript?

  - by Danjah

  This question of mine (currently unanswered), drove me toward finding a better solution to what I'm attempting. My requirements: chunks of code which can be arbitrarily added into a document, without an identifier: [div class="thing"] [elements... /] [/div] the objects are scanned for and found by an external script: var things = yd.getElementsBy(function(el){ return yd.hasClass('thing'); },null,document ); the objects must be individually configurable, what I have currently is identifier-based: [div class="thing" id="thing0"] [elements... /] [script type="text/javascript"] new Thing().init({ id:'thing0'; }); [/script] [/div] So I need to ditch the identifier (id="thing0") so there are no duplicates when more than one chunk of the same code is added to a page I still need to be able to config these objects individually, without an identifier SO! All of that said, I wondered about creating a dynamic global variable within the script block of each added chunk of code, within its script tag. As each 'thing' is found, I figure it would be legit to grab the innerHTML of the script tag and somehow convert that text into a useable JS object. Discuss. Ok, don't discuss if you like, but if you get the drift then feel free to correct my wayward thinking or provide a better solution - please! d

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• Python and a "time value of money" problem.

  - by jamieb

  (I asked this question earlier today, but I did a poor job of explaining myself. Let me try again) I have a client who is an industrial maintenance company. They sell service agreements that are prepaid 20 hour blocks of a technician's time. Some of their larger customers might burn through that agreement in two weeks while customers with fewer problems might go eight months on that same contract. I would like to use Python to help model projected sales revenue and determine how many billable hours per month that they'll be on the hook for. If each customer only ever bought a single service contract (never renewed) it would be easy to figure sales as monthly_revenue = contract_value * qty_contracts_sold. Billable hours would also be easy: billable_hrs = hrs_per_contract * qty_contracts_sold. However, how do I account for renewals? Assuming that 90% (or some other arbitrary amount) of customers renew, then their monthly revenue ought to grow geometrically. Another important variable is how long the average customer burns through a contract. How do I determine what the revenue and billable hours will be 3, 6, or 12 months from now, based on various renewal and burn rates? I assume that I'd use some type of recursive function but math was never one of my strong points. Any suggestions please? Edit: I'm thinking that the best way to approach this is to think of it as a "time value of money" problem. I've retitled the question as such. The problem is probably a lot more common if you think of "monthly sales" as something similar to annuity payments.

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• Generic Singleton Façade design pattern

  - by Paul

  Hi I try write singleton façade pattern with generics. I have one problem, how can I call method from generic variable. Something like this: T1 t1 = new T1(); //call method from t1 t1.Method(); In method SingletonFasadeMethod I have compile error: Error 1 'T1' does not contain a definition for 'Method' and no extension method 'Method' accepting a first argument of type 'T1' could be found (are you missing a using directive or an assembly reference?) Any advace? Thank, I am beginner in C#. All code is here: namespace GenericSingletonFasade { public interface IMyInterface { string Method(); } internal class ClassA : IMyInterface { public string Method() { return " Calling MethodA "; } } internal class ClassB : IMyInterface { public string Method() { return " Calling MethodB "; } } internal class ClassC : IMyInterface { public string Method() { return "Calling MethodC"; } } internal class ClassD : IMyInterface { public string Method() { return "Calling MethodD"; } } public class SingletonFasade<T1,T2,T3> where T1 : class,new() where T2 : class,new() where T3 : class,new() { private static T1 t1; private static T2 t2; private static T3 t3; private SingletonFasade() { t1 = new T1(); t2 = new T2(); t3 = new T3(); } class SingletonCreator { static SingletonCreator() { } internal static readonly SingletonFasade<T1,T2,T3> uniqueInstace = new SingletonFasade<T1,T2,T3>(); } public static SingletonFasade<T1,T2,T3> UniqueInstace { get { return SingletonCreator.uniqueInstace; } } public string SingletonFasadeMethod() { //Problem is here return t1.Method() + t2.Method() + t3.Method(); } } } I use this for my problem. public class SingletonFasade<T1, T2, T3> where T1 : class, IMyInterface, new() where T2 : class, IMyInterface, new() where T3 : class, IMyInterface, new() {//...} Is any solution without Interfaces ??

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• Binary files printing and desired precision

  - by yCalleecharan

  Hi, I'm printing a variable say z1 which is a 1-D array containing floating point numbers to a text file so that I can import into Matlab or GNUPlot for plotting. I've heard that binary files (.dat) are smaller than .txt files. The definition that I currently use for printing to a .txt file is: void create_out_file(const char *file_name, const long double *z1, size_t z_size){ FILE *out; size_t i; if((out = _fsopen(file_name, "w+", _SH_DENYWR)) == NULL){ fprintf(stderr, "***> Open error on output file %s", file_name); exit(-1); } for(i = 0; i < z_size; i++) fprintf(out, "%.16Le\n", z1[i]); fclose(out); } I have three questions: Are binary files really more compact than text files?; If yes, I would like to know how to modify the above code so that I can print the values of the array z1 to a binary file. I've read that fprintf has to be replaced with fwrite. My output file say dodo.dat should contain the values of array z1 with one floating number per line. I have %.16Le up in my code but I think that %.15Le is right as I have 15 precision digits with long double. I have put a dot (.) in the width position as I believe that this allows expansion to an arbitrary field to hold the desired number. Am I right? As an example with %.16Le, I can have an output like 1.0047914240730432e-002 which gives me 16 precision digits and the width of the field has the right width to display the number correctly. Is placing a dot (.) in the width position instead of a width value a good practice? Thanks a lot...

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• confusing fork system call

  - by benjamin button

  Hi, i was just checking the behaviour of fork system call and i found it very confusing. i saw in a website that Unix will make an exact copy of the parent's address space and give it to the child. Therefore, the parent and child processes have separate address spaces #include <stdio.h> #include <sys/types.h> int main(void) { pid_t pid; char y='Y'; char *ptr; ptr=&y; pid = fork(); if (pid == 0) { y='Z'; printf(" *** Child process ***\n"); printf(" Address is %p\n",ptr); printf(" char value is %c\n",y); sleep(5); } else { sleep(5); printf("\n ***parent process ***\n",&y); printf(" Address is %p\n",ptr); printf(" char value is %c\n",y); } } the output of the above program is : *** Child process *** Address is 69002894 char value is Z ***parent process *** Address is 69002894 char value is Y so from the above mentioned statement it seems that child and parent have separet address spaces.this is the reason why char value is printed separately and why am i seeing the address of the variable as same in both child and parent processes.? Please help me understand this!

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• How to initialize audio with Vala/SDL

  - by ioev

  I've been trying to figure this out for a few hours now. In order to start up the audio, I need to create an SDL.AudioSpec object and pass it to SDL.Audio.Open. The problem is, AudioSpec is a class with a private constructor, so when I try to create one I get: sdl.vala:18.25-18.43: error: `SDL.AudioSpec' does not have a default constructor AudioSpec audiospec = new SDL.AudioSpec(); ^^^^^^^^^^^^^^^^^^^ And if I try to just assign values to it's member vars like a struct (it's a struct in normal sdl) I get: sdl.vala:20.3-20.25: error: use of possibly unassigned local variable `audiospec' audiospec.freq = 22050; ^^^^^^^^^^^^^^^^^^^^^^^ I found the valac doc here: http://valadoc.org/sdl/SDL.AudioSpec.html But it isn't much help at all. The offending code block looks like this: // setup the audio configuration AudioSpec audiospec; AudioSpec specback; audiospec.freq = 22050; audiospec.format = SDL.AudioFormat.S16LSB; audiospec.channels = 2; audiospec.samples = 512; // try to initialize sound with these values if (SDL.Audio.open(audiospec, specback) < 0) { stdout.printf("ERROR! Check audio settings!\n"); return 1; } Any help would be greatly appreciated!

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• Is it safe to use random Unicode for complex delimiter sequences in strings?

  - by ccomet

  Question: In terms of program stability and ensuring that the system will actually operate, how safe is it to use chars like ¦, § or ‡ for complex delimiter sequences in strings? Can I reliable believe that I won't run into any issues in a program reading these incorrectly? I am working in a system, using C# code, in which I have to store a fairly complex set of information within a single string. The readability of this string is only necessary on the computer side, end-users should only ever see the information after it has been parsed by the appropriate methods. Because some of the data in these strings will be collections of variable size, I use different delimiters to identify what parts of the string correspond to a certain tier of organization. There are enough cases that the standard sets of ;, |, and similar ilk have been exhausted. I considered two-char delimiters, like ;# or ;|, but I felt that it would be very inefficient. There probably isn't that large of a performance difference in storing with one char versus two chars, but when I have the option of picking the smaller option, it just feels wrong to pick the larger one. So finally, I considered using the set of characters like the double dagger and section. They only take up one char, and they are definitely not going to show up in the actual text that I'll be storing, so they won't be confused for anything. But character encoding is finicky. While the visibility to the end user is meaningless (since they, in fact, won't see it), I became recently concerned about how the programs in the system will read it. The string is stored in one database, while a separate program is responsible for both encoding and decoding the string into different object types for the rest of the application to work with. And if something is expected to be written one way, is possibly written another, then maybe the whole system will fail and I can't really let that happen. So is it safe to use these kind of chars for background delimiters?

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