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  • ASP.NET DropDownList posting ""

    - by Daniel
    I am using ASP.NET forms version 3.5 in VB I have a dropdownlist that is filled with data from a DB with a list of countries The code for the dropdown list is <label class="ob_label"> <asp:DropDownList ID="lstCountry" runat="server" CssClass="ob_forminput"> </asp:DropDownList> Country*</label> And the code that the list is Dim selectSQL As String = "exec dbo.*******************" ' Define the ADO.NET objects. Dim con As New SqlConnection(connectionString) Dim cmd As New SqlCommand(selectSQL, con) Dim reader As SqlDataReader ' Try to open database and read information. Try con.Open() reader = cmd.ExecuteReader() ' For each item, add the author name to the displayed ' list box text, and store the unique ID in the Value property. Do While reader.Read() Dim newItem As New ListItem() newItem.Text = reader("AllSites_Countries_Name") newItem.Value = reader("AllSites_Countries_Id") CType(LoginViewCart.FindControl("lstCountry"), DropDownList).Items.Add(newItem) Loop reader.Close() CType(LoginViewCart.FindControl("lstCountry"), DropDownList).SelectedValue = 182 Catch Err As Exception Response.Redirect("~/error-on-page/") MailSender.SendMailMessage("*********************", "", "", OrangeBoxSiteId.SiteName & " Error Catcher", "<p>Error in sub FillCountry</p><p>Error on page:" & HttpContext.Current.Request.Url.AbsoluteUri & "</p><p>Error details: " & Err.Message & "</p>") Response.Redirect("~/error-on-page/") Finally con.Close() End Try When the form is submitted an error occurs which says that the string "" cannot be converted to the datatype integer. For some reason the dropdownlist is posting "" rather than the value for the selected country.

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  • How do you protect a common resource using mutexes?

    - by Steve
    I have a common resource, which I want 1 and only 1 instance of my application (or it's COM API) to have access to at any time. I have tried to protect this resource using mutexes, but when multiple threads of a host dotnet application try to access the COM object, the mutex doesn't seem to be released. This is the code I have used to protect my resource. repeat Mutex := CreateMutex(nil, True, PChar('Connections')); until (Mutex <> 0) and (GetLastError <> ERROR_ALREADY_EXISTS); try //use resource here! finally CloseHandle(Mutex); end; If I run the threads simultaneously, the first thread get's through (obviously, being the first one to create the mutex), but subsequent threads are caught in the repeat loop. If I run each thread at 5 second intervals, then all is ok. I suspect I'm not using mutexes correctly here, but I have found very little documentation about how to do this. Any ideas?

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  • Using GCC (MinGW) to compile OpenGL on Windows

    - by Casey
    I've searched on google and haven't been able to come up with a solution. I would like to compile some OpenGL programming using GCC. In the GL folder in GCC I have the following headers: gl.h glext.h glu.h Then in my system32 file I have the following .dll opengl32.dll glu32.dll glut32.dll If I wanted to write a simple OpenGL "Hello World" and link and compile with GCC, what is the correct process? I'm attempting to use this code: #include <GL/gl.h> #include <GL/glut.h> void display() { glClear(GL_COLOR_BUFFER_BIT); glFlush(); } int main(int argc, char **argv) { glutInit(&argc, argv); glutInitWindowSize(512,512); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); glutCreateWindow("The glut hello world program"); glutDisplayFunc(display); glClearColor(0.0, 0.0, 0.0, 1.0); glutMainLoop(); // Infinite event loop return 0; } Thank you in advance for the help.

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  • Java - SwingWorker - problem

    - by Yatendra Goel
    I am developing a Java Desktop Application. This app executes the same task public class MyTask implements Callable<MyObject> { in multiple thread simultaneously. Now, when a user clicks on a "start" button, I have created a SwingWorker myWorker and have executed it. Now, this myWorker creates multiple instances of MyTask and submits them to an ExecutorService. Each MyTask instance has a loop and generates an intermediate result at every iteration. Now, I want to collect these intermediate results from each MyTask instances as soon as they are generated. Then after collecting these intermediate results from every MyTask instance, I want to publish it through SwingWorker.publish(MyObject) so that the progress is shown on the EDT. Q1. How can I implement this? Should I make MyTask subclass of SwingWorker instead of Callable to get intermediate results also, because I think that Callable only returns final result. Q2. If the answer of Q1. is yes, then can you give me a small example to show how can I get those intermediate results and aggregate them and then publish them from main SwingWorker? Q3. If I can't use SwingWorker in this situation, then how can I implement this?

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  • Reducing Time Complexity in Java

    - by Koeneuze
    Right, this is from an older exam which i'm using to prepare my own exam in january. We are given the following method: public static void Oorspronkelijk() { String bs = "Dit is een boodschap aan de wereld"; int max = -1; char let = '*'; for (int i=0;i<bs.length();i++) { int tel = 1; for (int j=i+1;j<bs.length();j++) { if (bs.charAt(j) == bs.charAt(i)) tel++; } if (tel > max) { max = tel; let = bs.charAt(i); } } System.out.println(max + " keer " + let); } The questions are: what is the output? - Since the code is just an algorithm to determine the most occuring character, the output is "6 keer " (6 times space) What is the time complexity of this code? Fairly sure it's O(n²), unless someone thinks otherwise? Can you reduce the time complexity, and if so, how? Well, you can. I've received some help already and managed to get the following code: public static void Nieuw() { String bs = "Dit is een boodschap aan de wereld"; HashMap<Character, Integer> letters = new HashMap<Character, Integer>(); char max = bs.charAt(0); for (int i=0;i<bs.length();i++) { char let = bs.charAt(i); if(!letters.containsKey(let)) { letters.put(let,0); } int tel = letters.get(let)+1; letters.put(let,tel); if(letters.get(max)<tel) { max = let; } } System.out.println(letters.get(max) + " keer " + max); } However, I'm uncertain of the time complexity of this new code: Is it O(n) because you only use one for-loop, or does the fact we require the use of the HashMap's get methods make it O(n log n) ? And if someone knows an even better way of reducing the time complexity, please do tell! :)

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  • XMPP4R Callbacks dont seem to work

    - by Sid
    Im using xmpp4r and trying to get the hang of a basic chat feature that I wish to implement later in my Rails app. My fundamentals on Ruby Threads is still a bit shaky so I would appreciate any help on this. Though I register the callback i dont get a response from my gmail account. I am able to send a message but my ruby program terminates. In order to prevent it from terminating I tried to stop on of the threads in the program but I cant seem to get it working. require 'rubygems' require "xmpp4r/client" require "xmpp4r/roster" include Jabber def connect client = Client.new(JID::new("[email protected]")) client.connect client.auth("test") client.send(Presence.new.set_type(:available)) client end def create_message(message, to_email) msg = Jabber::Message::new(to_email, message) msg.type = :chat msg end def subscribe(email_id) pres = Presence.new.set_type(:subscribe).set_to(email_id) pres end client = connect roster = Roster::Helper.new(client) roster.add_subscription_request_callback do |item,pres| roster.accept_subscription(pres.from) end def create_callback(client) $t4= Thread.new do client.add_message_callback do |m| puts m.body puts "................................Callback working" end end end puts "Client has connected" msg = create_message("Welcome to the winter of my discontent", "[email protected]") client.send(msg) create_callback(client) def check(client) $t3 = Thread.new do loop do puts "t3 still running........." Thread.current.stop $t4.join end end end check(client)

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  • XSLT inserting once off custom text

    - by BeraCim
    Hi all: The folloiwng is a pre-existing xml file. I was wondering how can I insert a element before the first element using xslt? <XmlFile> <!-- insert another <tag> element here --> <tag> <innerTag> </innerTag> </tag> <tag> <innerTag> </innerTag> </tag> <tag> <innerTag> </innerTag> </tag> </XmlFile> I was thinking of using a for-each loop and test the position = 0, but upon the first occurence of the for-each its already too late. This is a once-off text so I can't combine it with other xslt templates that are already inside the xsl file. Thanks.

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  • What is a faster way of merging the values of this Python structure into a single dictionary?

    - by jcoon
    I've refactored how the merged-dictionary (all_classes) below is created, but I'm wondering if it can be more efficient. I have a dictionary of dictionaries, like this: groups_and_classes = {'group_1': {'class_A': [1, 2, 3], 'class_B': [1, 3, 5, 7], 'class_c': [1, 2], # ...many more items like this }, 'group_2': {'class_A': [11, 12, 13], 'class_C': [5, 6, 7, 8, 9] }, # ...and many more items like this } A function creates a new object from groups_and_classes like this (the function to create this is called often): all_classes = {'class_A': [1, 2, 3, 11, 12, 13], 'class_B': [1, 3, 5, 7, 9], 'class_C': [1, 2, 5, 6, 7, 8, 9] } Right now, there is a loop that does this: all_classes = {} for group in groups_and_classes.values(): for c, vals in group.iteritems(): for v in vals: if all_classes.has_key(c): if v not in all_classes[c]: all_classes[c].append(v) else: all_classes[c] = [v] So far, I changed the code to use a set instead of a list since the order of the list doesn't matter and the values need to be unique: all_classes = {} for group in groups_and_classes.values(): for c, vals in group.iteritems(): try: all_classes[c].update(set(vals)) except KeyError: all_classes[c] = set(vals) This is a little nicer, and I didn't have to convert the sets to lists because of how all_classes is used in the code. Question: Is there a more efficient way of creating all_classes (aside from building it at the same time groups_and_classes is built, and changing everywhere this function is called)?

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  • How to check if JavaScript object is JSON

    - by Wei Hao
    I have a nested JSON object that I need to loop through, and the value of each key could be a String, JSON array or another JSON object. Depending on the type of object, I need to carry out different operations. Is there any way I can check the type of the object to see if it is a String, JSON object or JSON array? I tried using typeof and instanceof but both didn't seem to work, as typeof will return an object for both JSON object and array, and instanceof gives an error when I do obj instanceof JSON. To be more specific, after parsing the JSON into a JS object, is there any way I can check if it is a normal string, or an object with keys and values (from a JSON object), or an array (from a JSON array)? For example: JSON var data = {"hi": {"hello": ["hi1","hi2"] }, "hey":"words" } JavaScript var jsonObj = JSON.parse(data); var level1 = jsonObj.hi; var text = jsonObj.hey; var arr = level1.hello; //how to check if level1 was formerly a JSON object? //how to check if arr was formerly a JSON array? //how to check if text is a string?

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  • Evaluating Javascript Arrays

    - by FailBoy
    I have an array that contains an array of arrays if that makes any sense. so for example: [[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]] I want to see whether an array exists withing the array, so if [1, 2, 3] is duplicated at all. I have tried to use the .indexOf method but it does find the duplicate. I have also tried Extjs to loop through the array manually and to evaluate each inner array, this is how I did it: var arrayToSearch = [[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]]; var newArray = [1, 2, 3]; Ext.each(arrayToSearch, function(entry, index){ console.log(newArray, entry); if(newArray == entry){ console.log(index); }; }); This also does not detect the duplicate. the console.log will output [1, 2, 3] and [1, 2, 3] but will not recognize them as equal. I have also tried the === evaluator but obviously since == doesn't work the === wont work. I am at wits end, any suggestions.

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  • Instantiating and starting a Scala Actor in a Map

    - by Bruce Ferguson
    I'm experimenting with a map of actors, and would like to know how to instantiate them and start them in one fell swoop... import scala.actors.Actor import scala.actors.Actor._ import scala.collection.mutable._ abstract class Message case class Update extends Message object Test { val groupings = "group1" :: "group2" :: "group3":: Nil val myActorMap = new HashMap[String,MyActor] def main(args : Array[String]) { groupings.foreach(group => myActorMap += (group -> new MyActor)) myActorMap("group2").start myActorMap("group2") ! Update } } class MyActor extends Actor { def act() { loop { react { case Update => println("Received Update") case _ => println("Ignoring event") } } } } The line: myActorMap("group2").start will grab the second instance, and let me start it, but I would like to be able to do something more like: groupings.foreach(group => myActorMap += (group -> (new MyActor).start)) but no matter how I wrap the new Actor, the compiler complains with something along the lines of: type mismatch; found : scala.actors.Actor required: com.myCompany.test.MyActor or various other complaints. I know it must be something simple to do with anonymous classes, but I can't see it right now. Any suggestions? Thanks in advance!!

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  • MySQL Gurus: How to pull a complex grid of data from MySQL database with one query?

    - by iopener
    Hopefully this is less complex than I think. I have one table of companies, and another table of jobs, and a third table with that contains a single entry for each employee in each job from each company. NOTE: Some companies won't have employees in some jobs, and some companies will have more than one employee in some jobs. The company table has a companyid and companyname field, the job table has a jobid and jobtitle field, and the employee table has employeeid, companyid, jobid and employeename fields. I want to build a table like this: +-----------+-----------+-----------+ | Company A | Company B | Company C | ------+-----------+-----------+-----------+ Job A | Emp 1 | Emp 2 | | ------+-----------+-----------+-----------+ Job B | Emp 3 | | Emp 4 | | | | Emp 5 | ------+-----------+-----------+-----------+ Job C | | Emp 6 | | | | Emp 7 | | | | Emp 8 | | ------+-----------+-----------+-----------+ I had previously been looping through a result set of jobs, and for each job, looping through a result set of each company, and for each company, looping through each employee and printing it in a table (gross, but performance was not supposed to be a consideration). The app has grown in popularity, and now we have 100 companies and hundreds of jobs, and the server is crapping out (all the id fields are indexed). Any suggestions on how to write a single query to get this data? I don't need the company names or job titles (obviously), but I do need some way to identify where each row from the result should be printed. I'm imagining a result set that just contained a long list of joined employees, and I could write a loop to use the companyid and employeeid values to tell me when to create a new cell or table row. This works as long as there aren't ZERO employees; I would need a NULL employee name for that I think? Am I completely on the wrong track? Thanks in advance for any ideas!

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  • jquery-infinite-carousel - jump 3 items instead of one

    - by Rob B
    Successfully used jquery-infinite-carousel in the past but for my current project I need it to loop forever AND also jump 3 items at a time. Example of how it works jumping 1 at a time here. jQuery.fn.carousel = function(previous, next, options){ var sliderList = jQuery(this).children()[0]; if (sliderList) { var increment = jQuery(sliderList).children().outerWidth("true"), elmnts = jQuery(sliderList).children(), numElmts = elmnts.length, sizeFirstElmnt = increment, shownInViewport = Math.round(jQuery(this).width() / sizeFirstElmnt), firstElementOnViewPort = 1, isAnimating = false; //console.log("increment = " + increment); //console.log("numElmts = " + numElmts); //console.log("shownInViewport = " + shownInViewport); for (i = 0; i < shownInViewport; i++) { jQuery(sliderList).css('width',(numElmts+shownInViewport)*increment + increment + "px"); jQuery(sliderList).append(jQuery(elmnts[i]).clone()); } jQuery(previous).click(function(event){ if (!isAnimating) { if (firstElementOnViewPort == 1) { jQuery(sliderList).css('left', "-" + numElmts * sizeFirstElmnt + "px"); firstElementOnViewPort = numElmts; console.log("firstElementOnViewPort = " + firstElementOnViewPort); } else { firstElementOnViewPort--; } jQuery(sliderList).animate({ left: "+=" + increment, y: 0, queue: true }, "swing", function(){isAnimating = false;}); isAnimating = true; } }); jQuery(next).click(function(event){ if (!isAnimating) { if (firstElementOnViewPort > numElmts) { firstElementOnViewPort = 2; jQuery(sliderList).css('left', "0px"); } else { firstElementOnViewPort++; } jQuery(sliderList).animate({ left: "-=" + (increment), y: 0, queue: true }, "swing", function(){isAnimating = false;}); isAnimating = true; } }); } };

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  • Complex LINQ paging algorithm

    - by sharepointmonkey
    We have a list of projects that may or may not have a collection of subprojects. Our report needs to contain all the projects except those that are the parent project of a subproject. I need to page this into pages of, say, 25 rows. But if subprojects appear on that page then ALL the subprojects of that project must appear on the same page. So more than 25 items may appear if necessary. I've got as far as var pagedProjects = db.Projects.Where(x => !x.SubProjects.Any()).Skip( (pageNo -1) * pageSize).Take(pageSize); Obviously, this fails the second part of the requirements. As a further pain in the arse, I need to have a pager control on the report. So I'll need to be able to calculate the total number of pages. I could loop through the whole table of projects but the performance will suffer. Can anybody come up with a paged solution? EDIT - I should probably mention that SubProjects joins back onto Projects via a selfreferencing foreign key so the whole lot comes back as an IQueryable<Project>.

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  • Save memory in Python. How to iterate over the lines and save them efficiently with a 2million line

    - by skyl
    I have a tab-separated data file with a little over 2 million lines and 19 columns. You can find it, in US.zip: http://download.geonames.org/export/dump/. I started to run the following but with for l in f.readlines(). I understand that just iterating over the file is supposed to be more efficient so I'm posting that below. Still, with this small optimization, I'm using 10% of my memory on the process and have only done about 3% of the records. It looks like, at this pace, it will run out of memory like it did before. Also, the function I have is very slow. Is there anything obvious I can do to speed it up? Would it help to del the objects with each pass of the for loop? def run(): from geonames.models import POI f = file('data/US.txt') for l in f: li = l.split('\t') try: p = POI() p.geonameid = li[0] p.name = li[1] p.asciiname = li[2] p.alternatenames = li[3] p.point = "POINT(%s %s)" % (li[5], li[4]) p.feature_class = li[6] p.feature_code = li[7] p.country_code = li[8] p.ccs2 = li[9] p.admin1_code = li[10] p.admin2_code = li[11] p.admin3_code = li[12] p.admin4_code = li[13] p.population = li[14] p.elevation = li[15] p.gtopo30 = li[16] p.timezone = li[17] p.modification_date = li[18] p.save() except IndexError: pass if __name__ == "__main__": run()

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  • Multi-dimensional array edge/border conditions

    - by kirbuchi
    Hi, I'm iterating over a 3 dimensional array (which is an image with 3 values for each pixel) to apply a 3x3 filter to each pixel as follows: //For each value on the image for (i=0;i<3*width*height;i++){ //For each filter value for (j=0;j<9;j++){ if (notOutsideEdgesCondition){ *(**(outArray)+i)+= *(**(pixelArray)+i-1+(j%3)) * (*(filter+j)); } } } I'm using pointer arithmetic because if I used array notation I'd have 4 loops and I'm trying to have the least possible number of loops. My problem is my notOutsideEdgesCondition is getting quite out of hands because I have to consider 8 border cases. I have the following handled conditions Left Column: ((i%width)==0) && (j%3==0) Right Column: ((i-1)%width ==0) && (i>1) && (j%3==2) Upper Row: (i<width) && (j<2) Lower Row: (i>(width*height-width)) && (j>5) and still have to consider the 4 corner cases which will have longer expressions. At this point I've stopped and asked myself if this is the best way to go because If I have a 5 line long conditional evaluation it'll not only be truly painful to debug but will slow the inner loop. That's why I come to you to ask if there's a known algorithm to handle this cases or if there's a better approach for my problem. Thanks a lot.

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  • SWT TabFolder: Weird Drawing Behaviour

    - by JesperGJensen
    Hello StackOverflow Experts Description I have an SWT Page with a TabFolder with a number of dynamically created TabItems. On each TabItem i crate a Composite and set the TabItem.setControl() to the Composite. I then use this Composite as the page on which i draw my items. I draw a set of Controls, including Textbox's and Labels. For the First, Default Tab, this works fine. No problems. Problem On tabs that is not the first tab i have the following problems: I am unable to visually alter then Edited/Enabled state of my Controls. I am unable to visually set the Text content of my elements My Controls look disabled and have a Greyed out look. But i am able to Select the content with my mouse and use CTRL+C to copy it out. So the text contet is there and they are Editable. Visually it is just not updated. Any comments are appeciated, Any requests for code, examples will be supplied and help Welcommed. Updates I tried added the suggest debug loop to the code, where i attempt to enable my Controls. This was the result: [main] INFO [dk.viking.controller.LayerController] - f038.stklok is now Editable [true] and enabled [true] [main] INFO [dk.viking.controller.LayerController] - true Text {} [main] INFO [dk.viking.controller.LayerController] - true Composite {} [main] INFO [dk.viking.controller.LayerController] - true TabFolder {} [main] INFO [dk.viking.controller.LayerController] - true Shell {Viking GUI}

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  • Does complex JOINs causes high coupling and maintenance problems ?

    - by ashkan.kh.nazary
    Our project has ~40 tables with complex relations.A colleague believes in using long join queries which enforces me to learn about tables outside of my module but I think I should not concern about tables not directly related to my module and use data access functions (written by those responsible for other modules) when I need data from them. Let me clarify: I am responsible for the ContactVendor module which enables the customers to contact the vendor and start a conversation about some specific product. Products module has it's own complex tables and relations with functions that encapsulate details (for example i18n, activation, product availability etc ...). Now I need to show the product title of some product related to some conversation between the vendor and customers. I may either write a long query that retrieves the product info along with conversation stuff in one shot (which enforces me to learn about Product tables) OR I may pass the relevant product_id to the get_product_info(int) function. First approach is obviously demanding and introduces many bad practices and things I normally consider fault in programming. The problem with the second approach seems to be the countless mini queries these access functions cause and performance loss is a concern when a loop tries to fetch product titles for 100 products using functions that each perform a separate query. So I'm stuck between "don't code to the implementation, code to interface" and performance. What is the right way of doing things ? UPDATE: I'm specially concerned about possible future modifications to those tables outside of my module. What if the Products module decided to change the way they are doing things? or for some reason modify the schema? It means some other modules would break or malfunction until the change is integrated to them. The usual ripple effect problem.

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  • How to get node without children in xQuery?

    - by mbrevoort
    So I have two nodes of elements that I'm essentially trying to join. I want the top level node to stay the same but the child nodes to be replaced by those cross referenced. Given: <stuff> <item foo="foo" boo="1"/> <item foo="bar" boo="2" /> <item foo="baz" boo="3"/> <item foo="blah boo="4""/> </stuff> <list a="1" b="2"> <foo>bar</foo> <foo>baz</foo> </list> I want to loop through "list" and cross reference elements in "stuff" for this result: <list a="1" b="2"> <item foo="bar" boo="2" /> <item foo="baz" boo="3"/> </list> I want to do this without having to know about what attributes might be on "list". In other words I don't want to have to explicitly call them out like attribute a { $list/@a }, attribute b { $list/@b }

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  • movie silent until button press, flash as3

    - by pixelGreaser
    I thought I could change the Boolean true/false value, but it's not working. How do I get this to hush, until the button is pressed? import flash.media.Sound; import flash.media.SoundChannel; var soundOn:Boolean = true; //music is ON when we start var myToons:TitleMusic = new TitleMusic(); var myChannel:SoundChannel = myToons.play(0,1000); // endless loop, in effect var myTransform:SoundTransform; mySoundButton.addEventListener(MouseEvent.CLICK,toggleSound); mySoundButton.buttonMode = true; mySoundButton.mouseChildren = false; function toggleSound(e:MouseEvent) { if(soundOn) { // turn sound off myTransform = new SoundTransform(); myTransform.volume = 0; // silent myChannel.soundTransform = myTransform; soundOn = false; mySoundButton.myButtonText.text = "click to turn sound ON"; } else // sound is off { // turn sound on myTransform = new SoundTransform(); myTransform.volume = 1; // full volume myChannel.soundTransform = myTransform; soundOn = true; mySoundButton.myButtonText.text = "click to turn sound OFF"; } }

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  • Lazy Sequences that "Look Ahead" for Project Euler Problem 14

    - by ivar
    I'm trying to solve Project Euler Problem 14 in a lazy way. Unfortunately, I may be trying to do the impossible: create a lazy sequence that is both lazy, yet also somehow 'looks ahead' for values it hasn't computed yet. The non-lazy version I wrote to test correctness was: (defn chain-length [num] (loop [len 1 n num] (cond (= n 1) len (odd? n) (recur (inc len) (+ 1 (* 3 n))) true (recur (inc len) (/ n 2))))) Which works, but is really slow. Of course I could memoize that: (def memoized-chain (memoize (fn [n] (cond (= n 1) 1 (odd? n) (+ 1 (memoized-chain (+ 1 (* 3 n)))) true (+ 1 (memoized-chain (/ n 2))))))) However, what I really wanted to do was scratch my itch for understanding the limits of lazy sequences, and write a function like this: (def lazy-chain (letfn [(chain [n] (lazy-seq (cons (if (odd? n) (+ 1 (nth lazy-chain (dec (+ 1 (* 3 n))))) (+ 1 (nth lazy-chain (dec (/ n 2))))) (chain (+ n 1)))))] (chain 1))) Pulling elements from this will cause a stack overflow for n2, which is understandable if you think about why it needs to look 'into the future' at n=3 to know the value of the tenth element in the lazy list because (+ 1 (* 3 n)) = 10. Since lazy lists have much less overhead than memoization, I would like to know if this kind of thing is possible somehow via even more delayed evaluation or queuing?

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  • Python: Catching / blocking SIGINT during system call

    - by danben
    I've written a web crawler that I'd like to be able to stop via the keyboard. I don't want the program to die when I interrupt it; it needs to flush its data to disk first. I also don't want to catch KeyboardInterruptedException, because the persistent data could be in an inconsistent state. My current solution is to define a signal handler that catches SIGINT and sets a flag; each iteration of the main loop checks this flag before processing the next url. However, I've found that if the system happens to be executing socket.recv() when I send the interrupt, I get this: ^C Interrupted; stopping... // indicates my interrupt handler ran Traceback (most recent call last): File "crawler_test.py", line 154, in <module> main() ... File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/socket.py", line 397, in readline data = recv(1) socket.error: [Errno 4] Interrupted system call and the process exits completely. Why does this happen? Is there a way I can prevent the interrupt from affecting the system call?

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  • how to get the value from a CSS class object in javascript

    - by amit
    I have to select an <a> element from the given class of objects. when i click on the anchor tag in the showcase_URL class, i want the jquery function to get the value from <a> tag. How can this be done? I cannot make this an id as I am running a while loop to construct all the elements in php. there would be multiple objects of this class. there is no definite selector through which I can get the value of the anchor tag. Help would be much appreciated. echo '<div id="content">'; echo '<div class="showcase_data">'; echo '<div class="showcase_HEAD">'.$row->title.'</div>'; echo '<div class="showcase_TYPE">'.$row->type.'</div>'; echo '<div class="showcase_date">&nbsp;&nbsp;'.$row->date.'</div>'; echo '<div class="showcase_THUMB" style="float: left;" ></div>'; echo '<div class="showcase_TEXT">'.$row->details.'</div><br/>'; echo '<div class="showcase_URL"><a class="purl" value='.$row->num.'href="'.$row->url.'">PROJECT URL</a></div>'; echo '</div>'; echo '</div>';

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  • AS3 variables handling by AVM/compiler/scope

    - by jchmielewski
    I have couple of questions about AS3 variables handling by AVM/compiler/scope .1. This code in Flash will throw an error: function myFunction() { var mc:MovieClip=new MovieClip(); var mc:MovieClip=new MovieClip(); } but it won`t throw an error in Flex (only warning in Editor). Why? .2. How Flash sees variables in loops? Apparently this: for (var i:int=0; i<2; i++) { var mc:MovieClip=new MovieClip(); } isn`t equal to just: var mc:MovieClip=new MovieClip(); var mc:MovieClip=new MovieClip(); because it will throw an error again as earlier in Flash, but in Flex in function not? Is Flash changing somehow my loop before compilation? .3. Where in a class in equivalent to timeline in Flash - where in class I would put code which I put normally on timeline (I assume it is not constructor because of what I have written earlier, or maybe it`s a matter of Flash/Flex compiler)?

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  • Ajax function partially fails when alert removed

    - by YsoL8
    Hello. I have a problem in the following code: //quesry the db for image information function queryDB (parameters) { var parameters = "p="+parameters; alert ("hello"); if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari xmlhttp=new XMLHttpRequest(); } else {// code for IE6, IE5 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { // use the info alert (xmlhttp.responseText); } } xmlhttp.open("POST", "js/imagelist.php", true); //Send the proper header information along with the request xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); xmlhttp.setRequestHeader("Content-length", parameters.length); xmlhttp.setRequestHeader("Connection", "close"); xmlhttp.send(parameters); } When I remove the alert statement 4 lines down I hit problems. This function is being called by a loop, and without the alert, I only get results for the last value sent to the statement. With it, I get everything I was expecting and really I'm at a loss to know why. I've heard that this may be a timing issue as I'm sending new requests before the old one is finished. I also heard polling being mentioned, but I can't find any information detailed enough. I'm new to synchronous services and I'm not really aware of the issues.

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