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  • Q on Python serialization/deserialization

    - by neil
    What chances do I have to instantiate, keep and serialize/deserialize to/from binary data Python classes reflecting this pattern (adopted from RFC 2246 [TLS]): enum { apple, orange } VariantTag; struct { uint16 number; opaque string<0..10>; /* variable length */ } V1; struct { uint32 number; opaque string[10]; /* fixed length */ } V2; struct { select (VariantTag) { /* value of selector is implicit */ case apple: V1; /* VariantBody, tag = apple */ case orange: V2; /* VariantBody, tag = orange */ } variant_body; /* optional label on variant */ } VariantRecord; Basically I would have to define a (variant) class VariantRecord, which varies depending on the value of VariantTag. That's not that difficult. The challenge is to find a most generic way to build a class, which serializes/deserializes to and from a byte stream... Pickle, Google protocol buffer, marshal is all not an option. I made little success with having an explicit "def serialize" in my class, but I'm not very happy with it, because it's not generic enough. I hope I could express the problem. My current solution in case VariantTag = apple would look like this, but I don't like it too much import binascii import struct class VariantRecord(object): def __init__(self, number, opaque): self.number = number self.opaque = opaque def serialize(self): out = struct.pack('>HB%ds' % len(self.opaque), self.number, len(self.opaque), self.opaque) return out v = VariantRecord(10, 'Hello') print binascii.hexlify(v.serialize()) >> 000a0548656c6c6f Regards

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  • How to use delegate to perform callback between caller and web service helper class?

    - by codemonkie
    I have 2 classes A and B, where they belongs to the same namespace but resides in seperate files namely a.cs and b.cs, where class B essentially is a helper wrapping a web service call as follow: public class A { public A() // constructor { protected static B b = new B(); } private void processResult1(string result) { // come here when result is successful } private void processResult2(string result) { // come here when result is failed } static void main() { b.DoJobHelper(...); } } public class B { private com.nowhere.somewebservice ws; public B() { this.ws = new com.nowhere.somewebservice(); ws.JobCompleted += new JobCompletedEventHandler(OnCompleted); } void OnCompleted(object sender, JobCompletedEventArgs e) { string s = e.Result; Guid taskID = (Guid)e.UserState; switch (s) { case "Success": // Call processResult1(); break; case "Failed": // Call processResult2(); break; default: break; } } public void DoJobHelper() { Object userState = Guid.NewGuid(); ws.DoJob(..., userState); } } (1) I have seen texts on the net on using delegates for callbacks but failed to apply that to my case. All I want to do is to call the appropriate processResult() method upon OnCompleted() event, but dunno how to and where to declare the delegate: public delegate void CallBack(string s); (2) There is a sender object passed in to OnCompleted() but never used, did I miss anything there? Or how can I make good use of sender? Any helps appreciated.

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  • Get an Arduino and Android phone to communicate over the web

    - by Saleem
    I am writing an Android application to communicate with my Arduino over the web. The Arduino is running a web server through an Ethernet shield. I am attaching my code, but I will explain it here so you will understand what I am trying to do. The Android sends an HTTP request in the format http://192.168.1.148/?Lights=1. The Arduino gets the request, executes the command (in this case turning on some lights) and then responds to the Android device by simply sending the string "Lights=On". The Android will then change the color of the button to notify the user that the command was executed successfully. The Arduino is getting the instruction and executing it and sending the response but my button color is not changing. I know that the Android device is getting the string because I added a debug line to change the text on the button to the received response. The relevant code for the Android device is: ((Button) v).setText(sb.toString()); //This works and the button text changes to "Lights=On". //Test response and update button if(sb.toString()=="Lights=On"){ v.getBackground().setColorFilter(0xFFFFFF00, PorterDuff.Mode.MULTIPLY); Drawable d = lightOff.getBackground(); lightOff.invalidateDrawable(d); d.clearColorFilter(); } The Arduino code is: if(s=="Lights"){ switch(client.read()){ case '0': digitalWrite(LightPin,0); client.print("Lights=Off"); //debug Serial.println("Lights=Off"); break; case '1': digitalWrite(LightPin,1); client.print("Lights=On"); Serial.println("Lights=On"); break; } } Please let me know if you need more of the code to answer this question.

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  • Regex to ensure group match doesn't end with a specific character

    - by AJ
    I'm having trouble coming up with a regular expression to match a particular case. I have a list of tv shows in about 4 formats: Name.Of.Show.S01E01 Name.Of.Show.0101 Name.Of.Show.01x01 Name.Of.Show.101 What I want to match is the show name. My main problem is that my regex matches the name of the show with a preceding '.'. My regex is the following: "^([0-9a-zA-Z\.]+)(S[0-9]{2}E[0-9]{2}|[0-9]{4}|[0-9]{2}x[0-9]{2}|[0-9]{3})" Some Examples: >>> import re >>> SHOW_INFO = re.compile("^([0-9a-zA-Z\.]+)(S[0-9]{2}E[0-9]{2}|[0-9]{4}|[0-9]{2}x[0-9]{2}|[0-9]{3})") >>> match = SHOW_INFO.match("Name.Of.Show.S01E01") >>> match.groups() ('Name.Of.Show.', 'S01E01') >>> match = SHOW_INFO.match("Name.Of.Show.0101") >>> match.groups() ('Name.Of.Show.0', '101') >>> match = SHOW_INFO.match("Name.Of.Show.01x01") >>> match.groups() ('Name.Of.Show.', '01x01') >>> match = SHOW_INFO.match("Name.Of.Show.101") >>> match.groups() ('Name.Of.Show.', '101') So the question is how do I avoid the first group ending with a period? I realize I could simply do: var.strip(".") However, that doesn't handle the case of "Name.Of.Show.0101". Is there a way I could improve the regex to handle that case better? Thanks in advance.

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  • Create dynamic factory method in PHP (< 5.3)

    - by fireeyedboy
    How would one typically create a dynamic factory method in PHP? By dynamic factory method, I mean a factory method that will autodiscover what objects there are to create, based on some aspect of the given argument. Preferably without registering them first with the factory either. I'm OK with having the possible objects be placed in one common place (a directory) though. I want to avoid your typical switch statement in the factory method, such as this: public static function factory( $someObject ) { $className = get_class( $someObject ); switch( $className ) { case 'Foo': return new FooRelatedObject(); break; case 'Bar': return new BarRelatedObject(); break; // etc... } } My specific case deals with the factory creating a voting repository based on the item to vote for. The items all implement a Voteable interface. Something like this: Default_User implements Voteable ... Default_Comment implements Voteable ... Default_Event implements Voteable ... Default_VoteRepositoryFactory { public static function factory( Voteable $item ) { // autodiscover what type of repository this item needs // for instance, Default_User needs a Default_VoteRepository_User // etc... return new Default_VoteRepository_OfSomeType(); } } I want to be able to drop in new Voteable items and Vote repositories for these items, without touching the implementation of the factory.

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  • django html/css windows mac problem width additional space on the top of the page

    - by rafal
    Hi, my problem is really strange... We are developing shopping-cart system in django. The problem is, when I change anything even single letter on my computer, strange space on the top of the page appears, see the picture... I don't know since when the problem appears. But if i go back to previous version (in this case 210, we use svn), everything is ok, until i change something. I'm using windows 7 and i tried to edit this file in notepad, notepad++, e and so on... In the case when my friend changes something in this 210 version on Macbook everything is ok. Have anyone any ideas? Also in source code of the page strange "-" is added before doctype, but it is only visible in chrome. But the problem is for all browsers...! what is more... for example my home page extends, categories.html and base.html, and in this case a have two "--". Of course If i change something in this two files base and home... PLEASE HELP!:) http://img402.imageshack.us/img402/5655/buguh.png [2]:

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  • mysql complex key or + auto increment key (guid)

    - by darko
    Hi, I have not very big db. I am using auto increment primary keys and in my case there is no problem with that. GUID is not necessary. I have a table containing this fields: from_destination to_testination shipper quantity Where the fields 1,2,3 needs to be unique. Also I have second table that for the fields 1,2,3 stores bought quantities per day One to many. from_destination to_destination shipper date reserved_quantity case 1 Is it better to make fields 1,2,3 as primary complex key in the first table and the same fields in the second table to be foreign key First table from_destination | to_destination | primary shipper | quaitity Second table second_id - autoincrement primary from_destination | to_destination | foreign key shipper | date reserved_quantity Case 2 or just to add auto increment filed in the first table and make fields 1,2,3 unique. In the second table there will be one ingeger foreign key pointing to the first table, and one auto increment key for the table. First table first_id - autoincrement primary from_destination | to_destination | unique shipper | quaitity Second table second_id - autoincrement primary first_id - forein date reserved_quantity If so why we need complex keys, when we can have one field auto increment or GUID and all other fields that are candidates for complex key to be unique. Regards

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  • GridView onTouch

    - by Jeff
    I am trying to set up a GridView of buttons that responds to onTouch. For example, if I swipe my finger across the screen horizontally, vertically or diagonally then I want the buttons which were touched to be selected. I tried setting OnTouchListener's for the buttons, but this didn't work, only the first button in the drag event received the onTouch events. Next I tried creating an OnTouchListener for the GridView and then using the X,Y coords to determine which buttons where touched. This doesn't seem to work either since the MOTION_DOWN events are only passed to the GridView's onTouch() if I start the drag on the very edge of the GridView. In fact if I drag my finger horizontally across the grid, the onTouch events aren't fired at all unless I start the drag at the edge of the GridView. Does anyone know of a better way to do this? Thanks in advance. gridview.setOnTouchListener(new View.OnTouchListener() { @Override public boolean onTouch(@SuppressWarnings("unused") View view, MotionEvent event) { float X = event.getX(); float Y = event.getY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN: System.out.println("Down: " + X + "," + Y); break; case MotionEvent.ACTION_MOVE: System.out.println("Move: " + X + "," + Y); break; case MotionEvent.ACTION_UP: System.out.println("Up: " + X + "," + Y); break; } return true; } }

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  • [C#] How to use delegate to perform callback between caller and web service helper class?

    - by codemonkie
    I have 2 classes A and B, where they belongs to the same namespace but resides in seperate files namely a.cs and b.cs, where class B essentially is a helper wrapping a web service call as follow: public class A { public A() // constructor { protected static B b = new B(); } private void processResult1(string result) { // come here when result is successful } private void processResult2(string result) { // come here when result is failed } static void main() { b.DoJobHelper(...); } } public class B { private com.nowhere.somewebservice ws; public B() { this.ws = new com.nowhere.somewebservice(); ws.JobCompleted += new JobCompletedEventHandler(OnCompleted); } void OnCompleted(object sender, JobCompletedEventArgs e) { string s; Guid taskID = (Guid)e.UserState; switch (s) { case "Success": // Call processResult1(); break; case "Failed": // Call processResult2(); break; default: break; } } public void DoJobHelper() { Object userState = Guid.NewGuid(); ws.DoJob(..., userState); } } (1) I have seen texts on the net on using delegates for callbacks but failed to apply that to my case. All I want to do is to call the appropriate processResult() method upon OnCompleted() event, but dunno how to and where to declare the delegate: public delegate void CallBack(string s); (2) There is a sender object passed in to OnCompleted() but never used, did I miss anything there? Or how can I make good use of sender? Any helps appreciated.

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  • Switch statement usage - C

    - by Jamie Keeling
    Hello, I have a thread function on Process B that contains a switch to perform certain operations based on the results of an event sent from Process A, these are stored as two elements in an array. I set the first element to the event which signals when Process A has data to send and I have the second element set to the event which indicates when Process A has closed. I have began to implement the functionality for the switch statement but I'm not getting the results as I expect. Consider the following: // //Thread function DWORD WINAPI ThreadFunc(LPVOID passedHandle) { for(i = 0; i < 2; i++) { ghEvents[i] = OpenEvent(EVENT_ALL_ACCESS, FALSE, TEXT("Global\\ProducerEvents")); if(ghEvents[i] == NULL) { getlasterror = GetLastError(); } } dwProducerEventResult = WaitForMultipleObjects( 2, ghEvents, FALSE, INFINITE); switch (dwProducerEventResult) { case WAIT_OBJECT_0 + 0: { //Producer sent data //unpackedHandle = *((HWND*)passedHandle); MessageBox(NULL,L"Test",L"Test",MB_OK); break; } case WAIT_OBJECT_0 + 1: { //Producer closed ExitProcess(1); break; } default: return; } } As you can see if the event in the first array is signalled Process B should display a simple message box, if the second array is signalled the application should close. When I actually close Process A, Process B displays the message box instead. If I leave the first case blank (Do nothing) both applications close as they should. Furthermore Process B sends data an error is thrown (When I comment out the unpacking): Have I implemented my switch statement incorrectly? I though I handled the unpacking of the HWND correctly too, any suggestions? Thanks for your time.

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  • Complex derived attributes in Django models

    - by rabidpebble
    What I want to do is implement submission scoring for a site with users voting on the content, much like in e.g. reddit (see the 'hot' function in http://code.reddit.com/browser/sql/functions.sql). My submission model currently keeps track of up and down vote totals. Currently, when a user votes I create and save a related Vote object and then use F() expressions to update the Submission object's voting totals. The problem is that I want to update the score for the submission at the same time, but F() expressions are limited to only simple operations (it's missing support for log(), date_part(), sign() etc.) From my limited experience with Django I can see 4 options here: extend F() somehow (haven't looked at the code yet) to support the missing SQL functions; this is my preferred option and seems to fit within the Django framework the best define a scoring function (much like reddit's 'hot' function) in my database, and have Django use the value of that function for the value of the score field; as far as I can tell, #2 is not possible wrap my two step voting process in a suitably isolated transaction so that I can calculate the voting totals in Python and then update the Submission's voting totals without fear that another vote against the submission could be added/changed in the meantime; I'm hesitant to take this route because it seems overly complex - what is a "suitably isolated transaction" in this case anyway? use raw SQL; I would prefer to avoid this entirely -- what's the point of an ORM if I have to revert to SQL for such a common use case as this! (Note that this coming from somebody who loves sprocs, but is using Django for ease of development.) Before I embark on this mission to extend F() (which I'm not sure is even possible), am I about to reinvent the wheel? Is there a more standard way to do this? It seems like such a common use case and yet in an hour of searching I have yet to find a common solution...

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  • Business entity: private instance VS single instance

    - by taoufik
    Suppose my WinForms application has a business entity Order, the entity is used in multiple views, each view handles a different domain or use-case in the application. As an example, one managing orders, the other one digging into one order and displaying additional data. If I'd use nHibernate (or any other ORM) and use one session/dataContext per view (or per db action), I'd end up getting two different instances for the same Order (let's say orderId = 1). Although functionally the same entity, they are technically two different instances. Yes, I could implement Equals/GetHashcode to make them "seem" the same. Why would you go for a single instance per entity vs private instances per view or per use-case? Having single instances has the advantage of sharing INotifyPropertyChanged events, and sharing additional (non-persistent) data. Having a private instance in each view would give you the flexibility of the undo functionality on a view level. In the example above, I'd allow the user to change order details, and give them the flexibility to not save the change. Here, synchronisation between the view/use-case happens on a data persistence level. What would your argument be?

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  • C# override WndProc in Control level to detect

    - by Nullstr1ng
    I have overridden WndProc in UserControl level to detect MouseDown, MouseUp, and MouseMove to any Control added in that UserControl. protected override void WndProc(ref Message m) { Point mouseLoc = new Point(); switch (m.Msg) { case WM_LBUTTONDOWN: System.Diagnostics.Debug.WriteLine("mouse down"); //this.OnMouseDown(new MouseEventArgs(MouseButtons.Left, 1, mouseLoc.X, mouseLoc.Y, 0)); break; case WM_LBUTTONUP: System.Diagnostics.Debug.WriteLine("mouse up"); //this.OnMouseDown(new MouseEventArgs(MouseButtons.Left, 1, mouseLoc.X,mouseLoc.Y, 0)); break; case WM_MOUSEMOVE: int lParam = m.LParam.ToInt32(); //mouseLoc.X = lParam & 0xFFFF; //mouseLoc.Y = (int)(lParam & 0xFFFF0000 >> 16); mouseLoc.X = (Int16)m.LParam; mouseLoc.Y = (Int16)((int)m.LParam >> 16); System.Diagnostics.Debug.WriteLine("mouse move: " + mouseLoc.X + ", " + mouseLoc.Y); //this.OnMouseDown(new MouseEventArgs(MouseButtons.Left, 1, mouseLoc.X,mouseLoc.Y, 0)); break; } base.WndProc(ref m); } MouseMove, Down, and Up are working when the mouse pointer is in UserControl but when the mouse pointer is on other control (inside my UserControl) it doesn't work. Am I doing something wrong? Currently developing a flick and scroll control.

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  • Spring bean's DESTROY-METHOD attribute and web-application "prototype"d bean

    - by EugeneP
    Can get work the attribute "destroy-method". First, even if I type non-existing method name into "destroy-method" attribute, Spring initialization completes fine (already strange!). Next, when a bean has a "prototype" scope, then I suppose it must be destroyed before the application is closed. That not happens, it is simply never called in my case. Though, after extracting this bean I can call this method explicitly and it does its job. Could you explain why this method is never called in my Spring 2.5 case? p.s. The method exists, it is public and has no arguments. It seems to be a more difficult task then I thought. The problem is that this destroy method is called whenever the context is closed, and this is a rare case. My question is this: I have a web app. I have a "prototype"-scoped bean. What I need is when the current session is closed, this destroy method was automatically called by Spring. I can do it by hand, but is there any solution how to make Spring do this job? It destroys the bean after the session is destroyed, it might be possible for Spring to call a method on that bean before destroying it?

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  • Accesing WinCE ComboBox DroppedDown property (.NET CF 2.0)

    - by PabloG
    I'm implementing custom behavior sub-classing the form controls, but I cannot manage to access the DroppedDown property of the ComboBox. Looking in the help, it's supposed to be supported in CF.NET 2.0: using System; using System.Collections.Generic; using System.ComponentModel; using System.Drawing; using System.Data; using System.Text; using System.Windows.Forms; namespace xCustomControls { public partial class xComboBox : System.Windows.Forms.ComboBox { private ComboBox comboBox1; public xComboBox() { InitializeComponent(); this.KeyDown += new KeyEventHandler(this.KeyDownHandler); } private void KeyDownHandler(object sender, KeyEventArgs e) { // DroppedDown doesn't appear in the IntelliSense of ComboBox. // or this.comboBox1. if (((ComboBox)sender).DroppedDown) // fail! return; switch (e.KeyData) { case Keys.Up: case Keys.Enter: case Keys.Down: e.Handled = true; this.Parent.SelectNextControl((Control)sender, e.KeyData != Keys.Up, true, true, true); ... fails with 'System.Windows.Forms.ComboBox' does not contain a definition for 'DroppedDown' and no extension method 'DroppedDown' accepting a first argument of type 'System.Windows.Forms.ComboBox' could be found How can I access the property? TIA, Pablo

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  • Help Modifying Generic REST Helper PHP Example Code to Support XML DOM

    - by Jennifer Baker
    Hi! I found this example PHP source code at HTTP POST from PHP, without cURL I need some help modifying the example PHP source to support XML DOM for manipulating a REST API. I thought that if I update the CASE statement for the XML section below from $r = simplexml_load_string($res); to $r = new DOMDocument(); $r->load($res); that it would work but it doesn't. :( Any help would be appreciated. function rest_helper($url, $params = null, $verb = 'GET', $format = 'xml') { $cparams = array( 'http' => array( 'method' => $verb, 'ignore_errors' => true ) ); if ($params !== null) { $params = http_build_query($params); if ($verb == 'POST') { $cparams['http']['content'] = $params; } else { $url .= '?' . $params; } } $context = stream_context_create($cparams); $fp = fopen($url, 'rb', false, $context); if (!$fp) { $res = false; } else { // If you're trying to troubleshoot problems, try uncommenting the // next two lines; it will show you the HTTP response headers across // all the redirects: // $meta = stream_get_meta_data($fp); // var_dump($meta['wrapper_data']); $res = stream_get_contents($fp); } if ($res === false) { throw new Exception("$verb $url failed: $php_errormsg"); } switch ($format) { case 'json': $r = json_decode($res); if ($r === null) { throw new Exception("failed to decode $res as json"); } return $r; case 'xml': $r = simplexml_load_string($res); if ($r === null) { throw new Exception("failed to decode $res as xml"); } return $r; } return $res; }

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  • Zend_Validate_Abstract custom validator not displaying correct error messages.

    - by Jeremy Dowell
    I have two text fields in a form that I need to make sure neither have empty values nor contain the same string. The custom validator that I wrote extends Zend_Validate_Abstract and works correctly in that it passes back the correct error messages. In this case either: isEmpty or isMatch. However, the documentation says to use addErrorMessages to define the correct error messages to be displayed. in this case, i have attached ->addErrorMessages(array("isEmpty"=>"foo", "isMatch"=>"bar")); to the form field. According to everything I've read, if I return "isEmpty" from isValid(), my error message should read "foo" and if i return "isMatch" then it should read "bar". This is not the case I'm running into though. If I return false from is valid, no matter what i set $this-_error() to be, my error message displays "foo", or whatever I have at index[0] of the error messages array. If I don't define errorMessages, then I just get the error code I passed back for the display and I get the proper one, depending on what I passed back. How do I catch the error code and display the correct error message in my form? The fix I have implemented, until I figure it out properly, is to pass back the full message as the errorcode from the custom validator. This will work in this instance, but the error message is specific to this page and doesn't really allow for re-use of code. Things I have already tried: I have already tried validator chaining so that my custom validator only checks for matches: ->setRequired("true") ->addValidator("NotEmpty") ->addErrorMessage("URL May Not Be Empty") ->addValidator([*customValidator]*) ->addErrorMessage("X and Y urls may not be the same") But again, if either throws an error, the last error message to be set displays, regardless of what the error truly is. I'm not entirely sure where to go from here. Any suggestions?

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  • Detecting whether user stayed after prompting onBeforeUnload

    - by Daniel Magliola
    In a web app I'm working on, I'm capturing onBeforeUnload to ask the user whether he really wants to exit. Now, if he decides to stay, there are a number of things I'd like to do. What I'm trying to figure out is that he actually chose to stay. I can of course declare a SetTimeout for "x" seconds, and if that fires, then it would mean the user is still there (because we didn't get unloaded). The problem is that the user can take any time to decide whether to stay or not... I was first hoping that while the dialog was showing, SetTimeout calls would not fire, so I could set a timeout for a short time and it'd only fire if the user chose to stay. However, timeouts do fire while the dialog is shown, so that doesn't work. Another idea I tried is capturing mouseMoves on the window/document. While the dialog is shown, mouseMoves indeed don't fire, except for one weird exception that really applies to my case, so that won't work either. Can anyone think of other way to do this? Thanks! (In case you're curious, the reason capturing mouseMove doesn't work is that I have an IFrame in my page, containing a site from another domain. If at the time of unloading the page, the focus is within the IFrame, while the dialog shows, then I get the MouseMove event firing ONCE when the mouse moves from inside the IFrame to the outside (at least in Firefox). That's probably a bug, but still, it's very likely that'll happen in our case, so I can't use this method).

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  • Ruby and duck typing: design by contract impossible?

    - by davetron5000
    Method signature in Java: public List<String> getFilesIn(List<File> directories) similar one in ruby def get_files_in(directories) In the case of Java, the type system gives me information about what the method expects and delivers. In Ruby's case, I have no clue what I'm supposed to pass in, or what I'll expect to receive. In Java, the object must formally implement the interface. In Ruby, the object being passed in must respond to whatever methods are called in the method defined here. This seems highly problematic: Even with 100% accurate, up-to-date documentation, the Ruby code has to essentially expose its implementation, breaking encapsulation. "OO purity" aside, this would seem to be a maintenance nightmare. The Ruby code gives me no clue what's being returned; I would have to essentially experiment, or read the code to find out what methods the returned object would respond to. Not looking to debate static typing vs duck typing, but looking to understand how you maintain a production system where you have almost no ability to design by contract. Update No one has really addressed the exposure of a method's internal implementation via documentation that this approach requires. Since there are no interfaces, if I'm not expecting a particular type, don't I have to itemize every method I might call so that the caller knows what can be passed in? Or is this just an edge case that doesn't really come up?

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  • Dependency between operations in scala actors

    - by paradigmatic
    I am trying to parallelise a code using scala actors. That is my first real code with actors, but I have some experience with Java Mulithreading and MPI in C. However I am completely lost. The workflow I want to realise is a circular pipeline and can be described as the following: Each worker actor has a reference to another one, thus forming a circle There is a coordinator actor which can trigger a computation by sending a StartWork() message When a worker receives a StartWork() message, it process some stuff locally and sends DoWork(...) message to its neighbour in the circle. The neighbours do some other stuff and sends in turn a DoWork(...) message to its own neighbour. This continues until the initial worker receives a DoWork() message. The coordinator can send a GetResult() message to the initial worker and wait for a reply. The point is that the coordinator should only receive a result when data is ready. How can a worker wait that the job returned to it before answering the GetResult() message ? To speed up computation, any worker can receive a StartWork() at any time. Here is my first try pseudo-implementation of the worker: class Worker( neighbor: Worker, numWorkers: Int ) { var ready = Foo() def act() { case StartWork() => { val someData = doStuff() neighbor ! DoWork( someData, numWorkers-1 ) } case DoWork( resultData, remaining ) => if( remaining == 0 ) { ready = resultData } else { val someOtherData = doOtherStuff( resultData ) neighbor ! DoWork( someOtherData, remaining-1 ) } case GetResult() => reply( ready ) } } On the coordinator side: worker ! StartWork() val result = worker !? GetResult() // should wait

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  • Conversion type

    - by Ruben
    Hi, I've got the following question. I've got one class "Instellingen" that's a property in 3 other classes public class Instellingen { private int _ID; } public class Class1: Label { private Instellingen _Instellingen; } public class Class2 : Label { private Instellingen _Instellingen; } public class Class3 : Label { private Instellingen _Instellingen; } If I've got another class, that uses the other classes (but it can be anyone of this 3 classes) Do i have to use a switch? or is there an easier way? public class AnotherClass { public AnotherClass () { GetInstellingenFromClass(new Class1()); GetInstellingenFromClass(new Class2()); GetInstellingenFromClass(new Class3()); } private void GetInstellingenFromClass(Control c) { switch (c.GetType.ToString()) { case "Class1": Class1 klasse = (Class1) c; //Do something with the _Instellingen of this class break; case "Class2": Class2 klasse2 = (Class2) c; //Do something with the _Instellingen of this class break; case "Class3": Class3 klasse3 = (Class3)c; //Do something with the _Instellingen of this class break; } } } (does there exists something so i can just do something like c._Instellingen -- without converting it first to the right type, where it doesn't matter what type c is?) I hope you understand my question. Thanks

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  • Pros/cons of reading connection string from physical file vs Application object (ASP.NET)?

    - by HaterTot
    my ASP.NET application reads an xml file to determine which environment it's currently in (e.g. local, development, production). It checks this file every single time it opens a connection to the database, in order to know which connection string to grab from the Application Settings. I'm entering a phase of development where efficiency is becoming a concern. I don't think it's a good idea to have to read a file on a physical disk ever single time I wish to access the database (very often). I was considering storing the connection string in Application["ConnectionString"]. So the code would be public static string GetConnectionString { if (Application["ConnectionString"] == null) { XmlDocument doc = new XmlDocument(); doc.Load(HttpContext.Current.Request.PhysicalApplicationPath + "bin/ServerEnvironment.xml"); XmlElement xe = (XmlElement) xnl[0]; switch (xe.InnerText.ToString().ToLower()) { case "local": connString = Settings.Default.ConnectionStringLocal; break; case "development": connString = Settings.Default.ConnectionStringDevelopment; break; case "production": connString = Settings.Default.ConnectionStringProduction; break; default: throw new Exception("no connection string defined"); } Application["ConnectionString"] = connString; } return Application["ConnectionString"].ToString(); } I didn't design the application so I figure there must have been a reason for reading the xml file every time (to change settings while the application runs?) I have very little concept of the inner workings here. What are the pros and cons? Do you think I'd see a small performance gain by implementing the function above? THANKS

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  • Commercial Website architecture question

    - by Maxime ARNSTAMM
    Hello everyone, I have to write an architecture case study but there are some things that i don't know, so i'd like some pointers on the following : The website must handle 5k simultaneous users. The backend is composed by a commercial software, some webservices, some message queues, and a database. I want to recommend to use Spring for the backend, to deal with the different elements, and to expose some Rest services. I also want to recommend wicket for the front (not the point here). What i don't know is : must i install the front and the back on the same tomcat server or two different ? and i am tempted to put two servers for the front, with a load balancer (no need for session replication in this case). But if i have two front servers, must i have two back servers ? i don't want to create some kind of bottleneck. Based on what i read on this blog a really huge charge is handle by one tomcat only for the first website mentionned. But i cannot find any info on this, so i can't tell if it seems plausible. If you can enlight me, so i can go on in my case study, that would be really helpful. Thanks :)

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  • Need simple advice for graph solving problem

    - by sap
    Hi there, a collegue of mine proposed to me an exercise from an online judge website, which is basically a graph solving problem of an evacuation plan on a small town. i dont need the answer (nor do i want it) i just need an advice on which is the best approach to solving it since im kinda new to these kind of problems. the problem consists of town buildings with workers and fallout shelters in case of a nuclear attack. i have to build an algorithm that will assign the workers of each building to one or more fallout shelters but in a way that some shelters wont became too overcrowded while others remain almost empty (else i would just make the workers go to the nearest one). the problem is this: http://acm.timus.ru/problem.aspx?space=1&num=1237 in case its offline heres the google cached version of it: http://webcache.googleusercontent.com/search?q=cache:t2EPCzezs7AJ:acm.timus.ru/problem.aspx%3Fspace%3D1%26num%3D1237+vladimir+kotov+evacuation+problem&cd=1&hl=pt-PT&ct=clnk&gl=pt what i've done so far is for each building get the nearest shelter and move the number of workers from that build equal to the shelter capacity. then move to the next building. but sometimes the number of workers is greater than the shelter capacity, in that case after i iterate through every building, ill just iterate then again apllying the same algorithm until every building has 0 workers in it, problem is this is hardly the best way to solve it. any tip is welcome, please dont feel like im asking for the answer, i just want an advice in the right direction of solving it. thanks in advance.

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  • How to display data stored in core data in a table view?

    - by Dipanjan Dutta
    Hello All, I have developed a core data model for my application. I need to display the saved data into a table view. For my app I have selected split view controller. I am writing down my codes below. Please help me in this regard and write me the code that needs to be added. This is very important as my continuation in my company depends on this. #import "RootViewController.h" #import "DetailViewController.h" #import "AddViewController.h" #import "EmployeeDetailsAppDelegate.h" /* This template does not ensure user interface consistency during editing operations in the table view. You must implement appropriate methods to provide the user experience you require. */ @interface RootViewController () - (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath; @end @implementation RootViewController @synthesize detailViewController, fetchedResultsController, managedObjectContext, results, empName; #pragma mark - #pragma mark View lifecycle - (void)viewDidLoad { results = [[NSMutableDictionary alloc]init]; [results setObject:empName.text forKey:@"EmployeeName"]; [self.tableView reloadData]; [super viewDidLoad]; } /* - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; } */ /* - (void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; } */ /* - (void)viewWillDisappear:(BOOL)animated { [super viewWillDisappear:animated]; } */ /* - (void)viewDidDisappear:(BOOL)animated { [super viewDidDisappear:animated]; } */ - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Ensure that the view controller supports rotation and that the split view can therefore show in both portrait and landscape. return YES; } - (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath { NSManagedObject *managedObject = [self.fetchedResultsController objectAtIndexPath:indexPath]; cell.textLabel.text = [[managedObject valueForKey:@"EmployeeName"] description]; } #pragma mark - #pragma mark Add a new object - (void)insertNewObject:(id)sender { AddViewController *add = [[AddViewController alloc]initWithNibName:@"AddViewController" bundle:nil]; self.modalPresentationStyle = UIModalPresentationFormSheet; add.wantsFullScreenLayout = NO; [self presentModalViewController:add animated:YES]; [add release]; } #pragma mark - #pragma mark Table view data source - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return 1; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } // Configure the cell. NSManagedObject *managedObject = [self.fetchedResultsController objectAtIndexPath:indexPath]; cell.textLabel.text = [[managedObject valueForKey:@"EmployeeName"] description]; return cell; } - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath { if (editingStyle == UITableViewCellEditingStyleDelete) { // Delete the managed object. NSManagedObject *objectToDelete = [self.fetchedResultsController objectAtIndexPath:indexPath]; if (self.detailViewController.detailItem == objectToDelete) { self.detailViewController.detailItem = nil; } NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext]; [context deleteObject:objectToDelete]; NSError *error; if (![context save:&error]) { /* Replace this implementation with code to handle the error appropriately. abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button. */ NSLog(@"Unresolved error %@, %@", error, [error userInfo]); abort(); } } } - (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath { // The table view should not be re-orderable. return NO; } #pragma mark - #pragma mark Table view delegate - (void)tableView:(UITableView *)aTableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { // Set the detail item in the detail view controller. NSManagedObject *selectedObject = [self.fetchedResultsController objectAtIndexPath:indexPath]; self.detailViewController.detailItem = selectedObject; } #pragma mark - #pragma mark Fetched results controller - (NSFetchedResultsController *)fetchedResultsController { if (fetchedResultsController != nil) { return fetchedResultsController; } /* Set up the fetched results controller. */ // Create the fetch request for the entity. NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; // Edit the entity name as appropriate. NSEntityDescription *entity = [NSEntityDescription entityForName:@"Details" inManagedObjectContext:managedObjectContext]; [fetchRequest setEntity:entity]; // Set the batch size to a suitable number. [fetchRequest setFetchBatchSize:20]; // Edit the sort key as appropriate. NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"EmployeeName" ascending:NO]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [fetchRequest setSortDescriptors:sortDescriptors]; // Edit the section name key path and cache name if appropriate. // nil for section name key path means "no sections". NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:nil cacheName:@"Root"]; aFetchedResultsController.delegate = self; self.fetchedResultsController = aFetchedResultsController; [aFetchedResultsController release]; [fetchRequest release]; [sortDescriptor release]; [sortDescriptors release]; return fetchedResultsController; } #pragma mark - #pragma mark Fetched results controller delegate - (void)controllerWillChangeContent:(NSFetchedResultsController *)controller { [self.tableView beginUpdates]; } - (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type { switch(type) { case NSFetchedResultsChangeInsert: [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeDelete: [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade]; break; } } - (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath { UITableView *tableView = self.tableView; switch(type) { case NSFetchedResultsChangeInsert: [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeDelete: [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeUpdate: [self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath]; break; case NSFetchedResultsChangeMove: [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]withRowAnimation:UITableViewRowAnimationFade]; break; } } - (void)controllerDidChangeContent:(NSFetchedResultsController *)controller { [self.tableView endUpdates]; } #pragma mark - #pragma mark Memory management - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Relinquish ownership any cached data, images, etc. that aren't in use. } - (void)viewDidUnload { // Relinquish ownership of anything that can be recreated in viewDidLoad or on demand. // For example: self.myOutlet = nil; } - (void)dealloc { [detailViewController release]; [fetchedResultsController release]; [managedObjectContext release]; [super dealloc]; } @end // // AddViewController.m // EmployeeDetails // // Created by Dipanjan on 15/02/11. // Copyright 2011 __MyCompanyName__. All rights reserved. // #import "AddViewController.h" #import "EmployeeDetailsAppDelegate.h" #import "RootViewController.h" @implementation AddViewController @synthesize empName; @synthesize empID; @synthesize empDepartment; @synthesize backButton; // The designated initializer. Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad. /* - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; if (self) { // Custom initialization. } return self; } */ /* // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; } */ -(void)saveDetails{ EmployeeDetailsAppDelegate *appDelegate = [[UIApplication sharedApplication]delegate]; NSManagedObjectContext *context = [appDelegate managedObjectContext]; NSManagedObject *newDetails; newDetails = [NSEntityDescription insertNewObjectForEntityForName:@"Details" inManagedObjectContext:context]; [newDetails setValue:empID.text forKey:@"EmployeeID"]; [newDetails setValue:empName.text forKey:@"EmployeeName"]; [newDetails setValue:empDepartment.text forKey:@"EmployeeDepartment"]; empID.text = @""; empName.text = @""; empDepartment.text = @""; NSLog(@"%@........----->>>...", newDetails); NSError *error; [context save:&error]; [self dismissModalViewControllerAnimated:YES]; } -(void)findDetails { EmployeeDetailsAppDelegate *appDelegate = [[UIApplication sharedApplication]delegate]; NSManagedObjectContext *context = [appDelegate managedObjectContext]; NSEntityDescription *entityDesc = [NSEntityDescription entityForName:@"Details" inManagedObjectContext:context]; NSFetchRequest *request = [[NSFetchRequest alloc]init]; [request setEntity:entityDesc]; NSPredicate *pred = [NSPredicate predicateWithFormat:@"(EmployeeName = %@)", empName.text]; [request setPredicate:pred]; NSManagedObject *matches = nil; NSError *error; NSArray *objects = [context executeFetchRequest:request error:&error]; if ([objects count] == 0) { } else { matches = [objects objectAtIndex:0]; empID.text = [matches valueForKey:@"EmployeeID"]; empDepartment.text = [matches valueForKey:@"EmployeeDepartment"]; } [request release]; [self dismissModalViewControllerAnimated:YES]; } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Overriden to allow any orientation. return YES; } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc. that aren't in use. } - (void)viewDidUnload { self.empName = nil; self.empID = nil; self.empDepartment = nil; [super viewDidUnload]; // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } - (void)dealloc { [empID release]; [empName release]; [empDepartment release]; [super dealloc]; } @end Please let me know the answer as soon as possible. Thank you. Regards, Dipanjan

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