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  • When designing an event, is it a good idea to prevent listeners from being added twice?

    - by Matt
    I am creating an event-based API where a user can subscribe to an event by adding listener objects (as is common in Java or C#). When the event is raised, all subscribed listeners are invoked with the event information. I initially decided to prevent adding an event listener more than once. If a listener is added that already exists in the listener collection, it is not added again. However, after thinking about it some more, it doesn't seem that most event-based structures actually prevent this. Was my initial instinct wrong? I'm not sure which way to go here. I guess I thought that preventing addition of an existing listener would help to avoid a common programming error. Then again, it could also hide a bug that would lead to code being run multiple times when it shouldn't.

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  • handling matrix data in python

    - by Ovisek
    I was trying to progressively subtract values of a 3D matrix. The matrix looks like: ATOM 1223 ZX SOD A 11 2.11 -1.33 12.33 ATOM 1224 ZY SOD A 11 -2.99 -2.92 20.22 ATOM 1225 XH HEL A 12 -3.67 9.55 21.54 ATOM 1226 SS ARG A 13 -6.55 -3.09 42.11 ... here the last three columns are representing values for axes x,y,z respectively. now I what I wanted to do is, take the values of x,y,z for 1st line and subtract with 2nd,3rd,4th line in a iterative way and print the values for each axes. I was using: for line in map(str.split,inp): x = line[-3] y = line[-2] z = line[-1] for separating the values, but how to do in iterative way. should I do it by using Counter.

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  • How to work with delegates and event handler for user control.

    - by Shantanu Gupta
    I have created a user control that contains a button. I am using this control on my winform which will be loaded at run time after fetching data from database. Now I need to remove a row from a datatable on the Click event of that button. The problem is that how do I capture that event in my form. Currently it goes in that user control's btn click event defination.

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  • Best practices for handling binary data in Ruby?

    - by StackedCrooked
    What are the best practices for reading and writing binary data in Ruby? In the code sample below I needed to send a binary file using over HTTP (as POST data): f = File.new("resp.der", "r") # binary file begin while true out.syswrite(f.sysread(1)) # out is an output stream (type IO) end rescue EOFError => err puts "Sent response." end While this code seems to do a good job, it probably isn't very idiomatic. How can I improve it?

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  • What is the best way to log errors in Zend Framework in my project at this stage?

    - by Pasta
    We built an app in Zend Framework and have not worked a lot in setting up error reporting and logging. Is there any way we could get some level or error reporting without too much change in the code? Is there a ErrorHandler plugin available? The basic requirement is to log errors that happens within the controller, missing controllers, malformed URLs, etc. I also want to be able to log errors within my controllers. Will using error controller here, help me identify and log errors within my controllers? How best to do this with minimal changes?

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  • ActionScripting Issue: adding/removing children

    - by user1890698
    I have three movie clips all linked to the stage and I want them to behave like a button/ But I am not using a button because I have not found a way to have each part (up, over, down, hit) be animated and not just change when the mouse is in use with it. So far I have been able to have all three appear on my stage and show when I have the mouse over and as well when I click, but I think I'm doing something wrong with removeChild. Each MC should appear one at a time and now all three show up when I hover over and seem to "flash". Here's my code: var mainMoon:swayingMoon = new swayingMoon(); mainMoon.x = 50; mainMoon.y = 10; addChild(mainMoon); var hoverMoon:glowMoon = new glowMoon(); hoverMoon.x = 50; hoverMoon.y = 10; var movieMoon:clickedMoon = new clickedMoon(); movieMoon.x = 50; movieMoon.y = 10; mainMoon.addEventListener(MouseEvent.ROLL_OVER, showHoverMoon); mainMoon.addEventListener(MouseEvent.ROLL_OUT, hideHoverMoon); hoverMoon.addEventListener(MouseEvent.CLICK, startMovieMoon) function showHoverMoon(event:MouseEvent):void { addChild(hoverMoon); } function hideHoverMoon(event:MouseEvent):void { removeChild(hoverMoon) } function startMovieMoon(event:MouseEvent):void { addChild(movieMoon); }

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  • Delphi: How to assign dynamically an event handler without overwriting the existing event handler?

    - by user193655
    I need to loop through Components and assign an event handler (for example Dynamically assigning OnClick event for all TButton to ShowMessage('You clicked on ' + (Sender as TButton).Name); The problem is that in some cases I alreasy assigned the TButton OnClick event. Is there a way to solve the problem? Let's imagine I have Button1 for which the harcoded onclick event handler is: ShowMessage('This is Button1'); After my "parsing" I would like that the full event handler for Button1 becomes: ShowMessage('This is Button1'); // design time event handler code ShowMessage('You clicked on ' + (Sender as TButton).Name); // runtime added Note: I am looking for a soliution that allows me to use TButton as it is without inheriting from it.

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  • Handling Model Inheritance in ASP.NET MVC2

    - by enth
    I've gotten myself stuck on how to handle inheritance in my model when it comes to my controllers/views. Basic Model: public class Procedure : Entity { public Procedure() { } public int Id { get; set; } public DateTime ProcedureDate { get; set; } public ProcedureType Type { get; set; } } public ProcedureA : Procedure { public double VariableA { get; set; } public int VariableB { get; set; } public int Total { get; set; } } public ProcedureB : Procedure { public int Score { get; set; } } etc... many of different procedures eventually. So, I do things like list all the procedures: public class ProcedureController : Controller { public virtual ActionResult List() { IEnumerable<Procedure> procedures = _repository.GetAll(); return View(procedures); } } but now I'm kinda stuck. Basically, from the list page, I need to link to pages where the specific subclass details can be viewed/edited and I'm not sure what the best strategy is. I thought I could add an action on the ProcedureController that would conjure up the right subclass by dynamically figuring out what repository to use and loading the subclass to pass to the view. I had to store the class in the ProcedureType object. I had to create/implement a non-generic IRepository since I can't dynamically cast to a generic one. public virtual ActionResult Details(int procedureID) { Procedure procedure = _repository.GetById(procedureID, false); string className = procedure.Type.Class; Type type = Type.GetType(className, true); Type repositoryType = typeof (IRepository<>).MakeGenericType(type); var repository = (IRepository)DependencyRegistrar.Resolve(repositoryType); Entity procedure = repository.GetById(procedureID, false); return View(procedure); } I haven't even started sorting out how the view is going to determine which partial to load to display the subclass details. I'm wondering if this is a good approach? This makes determining the URL easy. It makes reusing the Procedure display code easy. Another approach is specific controllers for each subclass. It simplifies the controller code, but also means many simple controllers for the many procedure subclasses. Can work out the shared Procedure details with a partial view. How to get to construct the URL to get to the controller/action in the first place? Time to not think about it. Hopefully someone can show me the light. Thanks in advance.

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  • What happens on a JMS queue when onMessage() throws a JMSException?

    - by user311121
    Hi, I'm using Spring 2.5 with my custom class that implements MessageListener. If a JmsException is thrown in my onMessage( ) method, what happens to the state of the queue? Is the message considered "delivered" by the queue the moment onMessage is called? Or does the JmsException trigger some kind of rollback and the message is re-entered on the queue? Thanks in advance!

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  • PHP turn off errors - in one file only

    - by Industrial
    Hi! I am well aware about error_reporting(0); & ini_set('display_errors', "Off"); to make error messages go away. What would be an appropriate way to do this - for a specific file or part of code only? Surpressing errors with @'s seems like a bad idea since it apparently slows the code down... Thanks!

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  • Handling text menu in Python

    - by PulpFiction
    Hi all. I am trying to create a text based menu in Python. Here is the code: #!/usr/bin/env python def testcaseOutput(): print '1. Add. 2. Subtract. 3. Divide. 4. Multiply' try: answer = int(raw_input('Enter a value (1 - 4) >. ')) except ValueError: print 'Invalid input. Enter a value between 1 -4 .' testcaseOutput() if answer in range(1, 5): return answer else: print 'Invalid input. Enter a value between 1 - 4.' testcaseOutput() My question: When the user enters an invalid input, i.e. not a number, I want this function to get called again. So I used the recursive approach which I think is bad design. I use that approach again in the if answer in range(1, 5). Is there any other way to handle this? I need the prompt called again when there is an invalid input. Also, is there any way I can club the two constraints: check whether input is a number and check whether the number is in the range(1,5) together? As you can see, I am checking that individually.

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  • Trigger Event after values have been commited for validation purposes

    - by www.jefferyfernandez.id.au
    I have a Flex component with a form and on creationComplete, I load some data onto the form textInputs. After the Form TextInputs have got their values, I want to trigger an event so the Parent of the component can validate the values on the TextInputs and based on the validation results, I perform some enable/disable of other interfaces. I have the following dispatch code: this.dispatchEvent(new PersonalDetailsEvent(PersonalDetailsEvent.LOADED_DATA_EVENT)); The event is dispatched and is captured by the parent. But upon performing the validation, some TextInputs always fail the validation. I thought it could be because of a race condition and so I used callLater() with same results. So in the end I am now using a timer to dispatch the event which is not ideal. Does anyone have a solution to this problem. It is really annoying that a timer needs to be used for this scenario.

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  • Proper mechanism for sending PHP errors to the client

    - by Chris
    Greetings, I was trying to discover a proper way to send captured errors or business logic exceptions to the client in an Ajax-PHP system. In my case, the browser needs to react differently depending on whether a request was successful or not. However in all the examples I've found, only a simple string is reported back to the browser in both cases. Eg: if (something worked) echo "Success!"; else echo "ERROR: that failed"; So when the browser gets back the Ajax response, the only way to know if an error occurred would be to parse the string (looking for 'error' perhaps). This seems clunky. Is there a better/proper way to send back the Ajax response & notify the browser of an error? Thank you.

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  • [grails + xfire] How to handle errors in SOAP services?

    - by Mulone
    Hi all, I'm implementing a web service on the xfire plugin. I was wondering how I'm supposed to handle the errors. I tried with this setup but the error is not returned to the SOAP client: GaSession[] myMethod( String userId ) throws MyException{ GaUser user = GaUser.findByUserId( userId ) if (!user) throw new MyException("user ${userId} does not exist") // do stuff and return valid results } Is there a standard way to handle errors and return them to the client in a clear way? My log is full of messages like: 2010-06-13 18:20:40,926 [Thread-289] DEBUG aegis.XMLClassMetaInfoManager - Mapping file : /com/mycompany/MyClass.aegis.xml not found. Is there a way to fix this? Cheers!

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  • Likelihood of IOError during print vs. write

    - by jkasnicki
    I recently encountered an IOError writing to a file on NFS. There wasn't a disk space or permission issue, so I assume this was just a network hiccup. The obvious solution is to wrap the write in a try-except, but I was curious whether the implementation of print and write in Python make either of the following more or less likely to raise IOError: f_print = open('print.txt', 'w') print >>f_print, 'test_print' f_print.close() vs. f_write = open('write.txt', 'w') f_write.write('test_write\n') f_write.close() (If it matters, specifically in Python 2.4 on Linux).

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  • related to list and file handling?

    - by kaushik
    i have file with contents in list form such as [1,'ab','fgf','ssd'] [2,'eb','ghf','hhsd'] [3,'ag','rtf','ssfdd'] i want to read that file line by line using f.readline and assign thn to a list so as to use it is the prog as a list for using list properties tried like k=[ ] k=f.readline() print k[1] i xpected a result to show 2nd element in the list in first line but it showed the first bit and gave o/p as '1' how to get the xpected output.. please suggest

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