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  • Javascript storing properties and functions in variables

    - by richard
    Hello, I'm having trouble with my programming style and I hope to get some feedback here. I recently bought Javascript: The Good Parts and while I find this a big help, I'm still having trouble designing this application. Especially when it comes to writing function and methods. Example: I have a function that let's the user switches games in my app. This function updates game-specific information in the current view. var games = { active: Titanium.App.Properties.getString('active_game'), gameswitcher_positions: { 'Game 1': 0, 'Game 2': 1, 'Game 3': 2, 'Game 4': 3, 'Game 5': 4 }, change: function(game) { if (active_game !== game) { gameswitcher.children[this.gameswitcher_positions[this.active]].backgroundImage = gameswitcher.children[this.gameswitcher_positions[this.active]].backgroundImage.replace('_selected', ''); gameswitcher.children[this.gameswitcher_positions[game]].backgroundImage = gameswitcher.children[this.gameswitcher_positions[game]].backgroundImage.replace('.png', '_selected.png'); events.update(game); this.active = game; } }, init: function() { gameswitcher.children[this.gameswitcher_positions[this.active]].backgroundImage = gameswitcher.children[this.gameswitcher_positions[this.active]].backgroundImage.replace('.png', '_selected.png'); events.update(this.active); } }; gameswitcher is a container view which contains buttons to switch games. I am not satisfied with this approach but I cannot think of a better one. Should I place the gameswitcher_positions outside of the variable in a seperate variable instead of as a property? And what about the active game? Please give me feedback, what am I doing wrong?

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  • Django: order by count of a ForeignKey field?

    - by AP257
    This is almost certainly a duplicate question, in which case apologies, but I've been searching for around half an hour on SO and can't find the answer here. I'm probably using the wrong search terms, sorry. I have a User model and a Submission model. Each Submission has a ForeignKey field called user_submitted for the User who uploaded it. class Submission(models.Model): uploaded_by = models.ForeignKey('User') class User(models.Model): name = models.CharField(max_length=250 ) My question is pretty simple: how can I get a list of the three users with the most Submissions? I trued creating a num_submissions method on the User model: def num_submissions(self): num_submissions = Submission.objects.filter(uploaded_by=self).count() return num_submissions and then doing: top_users = User.objects.filter(problem_user=False).order_by('num_submissions')[:3] but this fails, as do all the other things I've tried. Can I actually do it using a smart database query? Or should I just do something more hacky in the views file?

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  • jquery callback functions failing to finish execution

    - by calumbrodie
    I'm testing a jquery app i've written and have come across some unexpected behaviour $('button.clickme').live('click',function(){ //do x (takes 2 seconds) //do y (takes 4 seconds) //do z (takes 0.5 seconds) }) The event can be triggered by a number of buttons. What I'm finding is that when I click each button slowly (allowing 10 seconds between clicks) - my callback function executes correctly (actions x, y & z complete). However If I rapidly click buttons on my page it appears that the function sometimes only completes up to step x or y before terminating. My question: Is it the case that if this function is fired by a clicking second DOM element, while the first callback function is completing - will jQuery terminate the first callback and start over again? Do I have to write my callback function explicitly outside the event handler and then call it?? function doStuff() { //do x //do y //do z ( } $('button.clickme).live('click',doStuff()) If this is the case can someone explain why this is happening or give me a link to some advice on best practice on closures etc - I'd like to know the BEST way to write jQuery to improve performance etc. Thanks

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  • Visitor Pattern can be replaced with Callback functions?

    - by getit
    Is there any significant benefit to using either technique? In case there are variations, the Visitor Pattern I mean is this: http://en.wikipedia.org/wiki/Visitor_pattern And below is an example of using a delegate to achieve the same effect (at least I think it is the same) Say there is a collection of nested elements: Schools contain Departments which contain Students Instead of using the Visitor pattern to perform something on each collection item, why not use a simple callback (Action delegate in C#) Say something like this class Department { List Students; } class School { List Departments; VisitStudents(Action<Student> actionDelegate) { foreach(var dep in this.Departments) { foreach(var stu in dep.Students) { actionDelegate(stu); } } } } School A = new School(); ...//populate collections A.Visit((student)=> { ...Do Something with student... }); *EDIT Example with delegate accepting multiple params Say I wanted to pass both the student and department, I could modify the Action definition like so: Action class School { List Departments; VisitStudents(Action<Student, Department> actionDelegate, Action<Department> d2) { foreach(var dep in this.Departments) { d2(dep); //This performs a different process. //Using Visitor pattern would avoid having to keep adding new delegates. //This looks like the main benefit so far foreach(var stu in dep.Students) { actionDelegate(stu, dep); } } } }

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  • Generate combinations by order and fixed length.

    - by roconmachine
    Suppose there is array main[] = [a,b,c,....z]; a[] = [a1,a2,a3,....] , b[] = [b1,b2,b3,....] and so on. So if we generate combination in main.length of ordered then it looks like ..... a1 b1 c1, a1 b1 c2, a1 b1 c3 ...... a1 b2 c1, a1 b3 c1, ..... a2 b1 c1, a3 b1 c1, ..... and total count will be a.length * b.length * c.length ........ = ? So write a code in any language to generate those combination. all the best. alex

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  • CRC function without order dependency

    - by Pirks
    I need a CRC mechanism to calculate the CRC of a number of strings, such that, given two strings, A and B, the sum crc(A) + crc(B) == crc(A+B). P.S. XOR is too weak---the algorithm should be not trivial for reverse engineering.

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  • Re-order mysql rows using PHP

    - by dave e
    | id | url | title | menu_id | ------+--------+--------+---------- | 1 | http://| link 1 | 1 | | 2 | http://| link 2 | 2 | | 3 | http://| link 3 | 3 | | 4 | http://| link 4 | 4 | Hi, I was wondering if its possible using PHP to reorder the above to something like below. I am trying to generate a menu which can easily be reordered by clicking an up or down arrow. I have no idea where to start. Any help would be much appreciated. | id | url | title | menu_id | ------+--------+--------+---------- | 1 | http://| link 1 | 2 | | 2 | http://| link 2 | 4 | | 3 | http://| link 3 | 3 | | 4 | http://| link 4 | 1 |

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  • Teaching a kid to type in order to start programming

    - by at
    My 5 year old wants to start programming, but he doesn't yet know how to type without looking for each letter 1 at a time. I know it's going to frustrate him to go so slow because of his typing speed. And it's not going to be fun looking for all the letters constantly... So what's the best way to get him to type fast? Clearly he'll need to type a lot of punctuation like semicolons, colons and symbols. So his little hands will have to get used to spreading over the keyboard... I did some google searches and found some very poor looking apps that focused on the letters.

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  • functions in F# .. why is it not compiling

    - by Tanmoy
    Hi, I have written two versions of code. The first one works as expected and print "Hi". the second one gives me error that "block following this let is unfinished" 1st version #light let samplefn() = let z = 2 let z = z * 2 printfn "hi" samplefn() 2nd version #light let samplefn() = let z = 2 let z = z * 2 samplefn() Only difference is the printfn is absent in the second version. I am using Visual Studio 2010 as my IDE. I am very new to F# but this error seems very strange to me. I guess I am missing some very important concept. Please explain. Edit: Also if I do it outside the function I get error even with the first version of code. #light let z = 2 let z = z * 2 printfn "Error: Duplicate definition of value z"

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  • order of initialization in Java

    - by M.H
    Hi, I want to ask why java initializes the static objects before the non-static objects ? in this example b3 will be initialized after b4 and b5 : class Cupboard { Bowl b3 = new Bowl(3); static Bowl b4 = new Bowl(4); Cupboard() {} static Bowl b5 = new Bowl(5); }

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  • Using :limit and :order in the associated model

    - by r2b2
    Hello, Is there any way i can limit the results of an associated model? This what i was trying to do : <ul> <% account.logins.slice(0,5).sort_by(&:login_date).reverse.each do |login| -%> <li><%=h login.login_date.strftime("%d.%m.%Y")%></li> <% end -%> </ul> I'm trying to get the last five logins of the account. I cant seem to do it with account.logins(:limit=5) Thanks !

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  • Using functions like formulas in Excel

    - by Arlen Beiler
    I am trying to use a formula to get a letter of the alphabet. Formula: =Keytable(RANDOM,ROW()) Function: Function KeyTable(seed As Long, position As Long) As String Dim i As Long Stop Dim calpha(1 To 26) As String Dim alpha(1 To 26) As String For i = 1 To 26 alpha(i) = Chr(i + UPPER_CASE - 1) Next i For i = 1 To 26 calpha(i) = alpha(seed Mod 27 - i) Next i Stop KeyTable = calpha(position) End Function Result: #Value! When I step through the function, it never gets to the second stop.

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  • jquery live() method on custom functions

    - by user271619
    I have a custom event handler, or I suppose some call it a custom jquery function. My problem is I'm trying to apply the live() method to it. But I'm not too successful. Here's a simple custom jquery function: $.fn.myFunction = function() { return $(this).addClass('changed'); } And here I use it: $('.changePlease').myFunction(); Ok, simple enough. But how do I apply the live() method to it?? I actually have no idea if that's even possible. But I do use live() for other things, like: $(".changePlease").live("click",function(){ alert("hello"); }); Any thoughts on this?

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  • prevent using functions before initialization, constructors-like in C

    - by Hernán Eche
    This is the way I get to prevent funA,funB,funC, etc.. for being used before init #define INIT_KEY 0xC0DE //any number except 0, is ok static int initialized=0; int Init() { //many init task initialized=INIT_KEY; } int funA() { if (initialized!=INIT_KEY) return 1 //.. } int funB() { if (initialized!=INIT_KEY) return 1 //.. } int funC() { if (initialized!=INIT_KEY) return 1 //.. } The problem with this approach is that if some of those function is called within a loop so "if (initialized!=INIT_KEY)" is called again, and again, although it's not necessary. It's a good example of why constructors are useful haha, If it were an object I would be sure that when was created initialization was called, but in C, I don't know how to do it. Any other ideas are welcome!

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  • Anonymous functions in C#

    - by Maxim Gershkovich
    The following syntax is valid VB.NET code Dim myCollection As New List(Of Stock) myCollection.Add(New Stock(Guid.NewGuid, "Item1")) myCollection.Add(New Stock(Guid.NewGuid, "Item2")) Dim res As List(Of Stock) = myCollection.FindAll(Function(stock As Stock) As Boolean If stock.Description = "Item2" Then Return True End If Return False End Function) How can I accomplish the same thing in C#? I have tried... myCollection.FindAll(bool delegate(Stock stock) { if (blah blah) { } }); But it appears I have somehow structured it incorrectly as I get the following error. "Error 1 Invalid expression term 'bool'"

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  • what functions are called when passing value to function

    - by Tim
    In C++, if an object of a class is passed as a parameter into a function, the copy constructor of the class will be called. I was wondering if the object is of nonclass type, what function will be called? Similarly in C, what function is called when passing values or address of variables into a function? Thanks and regards!

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  • Evaluating and graphing functions in Matlab

    - by thiol3
    New to programming, I am trying to graph the following Gaussian function in Matlab (should graph in 3 dimensions) but am making some mistakes somewhere. What is wrong? sigma = 1 for i = 1:20 for j = 1:20 z(i,j) = (1/(2*pi*sigma^2))*exp(-(i^2+j^2)/(2*sigma^2)); end end surf(z)

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  • Does JSLint parse DOM functions?

    - by Paul
    I tried to use the parse() function of JSLint to parse three pieces of JavaScript code: function(b, c){var a = b + c; return a; } window.addEventListener('click', click_hanlder, true); document.documentElement.innerHTML; Here's the code, which is copied and pasted from the JSLint self-parse example: ` try { parse = make_parse(); var source = "something to parse";//replaced by the code above tree = parse(source); if (tree) { document.write(JSON.stringify(tree, ['key', 'name', 'message', 'value', 'arity', 'first', 'second', 'third', 'fourth'], 4)); } } catch (e) { document.write(JSON.stringify(e, ['name', 'message', 'from', 'to', 'key', 'value', 'arity', 'first', 'second', 'third', 'fourth'], 4)); } ` The output: returns a correct tree. returns a tree with only one node of "window". crashes the browser. I'm wondering whether JSLint doesn't support DOM function.

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  • How cast in XML for aggregate functions

    - by renegm
    In SQL Server 2008. I need execute a query like that: DECLARE @x AS xml SET @x=N'<r><c>First Text</c></r><r><c>Other Text</c></r>' SELECT @x.query('fn:max(r/c)') But return nothing (apparently because convert xdt:untypedAtomic to numeric) How to "cast" r/c to varchar? Something like SELECT @x.query('fn:max(«CAST(r/c «AS varchar(20))»)') Edit: Using Nodes the function MAX is from T-SQL no fn:max function In this code: DECLARE @x xml; SET @x = ''; SELECT @x.query('fn:max((1, 2))'); SELECT @x.query('fn:max(("First Text", "Other Text"))'); both query return expected: 2 and "Other Text" fn:max can evaluate string expression ad hoc. But the first query dont work. How to force string arguments to fn:max?

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  • C#: reflection alternative for switch on enum in order to select namespace/class

    - by Am
    Hi, I have an interface named IHarvester. There are 3 implementations of that interface, each under their own namespace: Google Yahoo Bing A HarvesterManager uses the given harvester. It knows the interface and all 3 implementations. I want some way of letting the class user say in which harvester it wants to use. And in the code select that implementation, without a switch-case implementation. Can reflection save my day? Here is the code bits: // repeat for each harvester namespace Harvester.Google { public abstract class Fetcher : BaseHarvester, IInfoHarvester {...} } public enum HarvestingSource { Google, Yahoo, Bing, } class HarvesterManager { public HarvestingSource PreferedSource {get;set;} public HarvestSomthing() { switch (PreferedSource) .... // awful... } } Thanks.

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  • Returning multiple aggregate functions as rows

    - by SDLFunTimes
    I need some help formulating a select statement. I need to select the total quantity shipped for each part with a distinct color. So the result should be a row with the color name and the total. Here's my schema: create table s ( sno char(5) not null, sname char(20) not null, status smallint, city char(15), primary key (sno) ); create table p ( pno char(6) not null, pname char(20) not null, color char(6), weight smallint, city char(15), primary key (pno) ); create table sp ( sno char(5) not null, pno char(6) not null, qty integer not null, primary key (sno, pno) );

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