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  • Circular dependency with generics

    - by devoured elysium
    I have defined the following interface: public interface IStateSpace<State, Action> where State : IState where Action : IAction<State, Action> // <-- this is the line that bothers me { void SetValueAt(State state, Action action); Action GetValueAt(State state); } Basically, an IStateSpace interface should be something like a chess board, and in each position of the chess board you have a set of possible movements to do. Those movements here are called IActions. I have defined this interface this way so I can accommodate for different implementations: I can then define concrete classes that implement 2D matrix, 3D matrix, graphs, etc. public interface IAction<State, Action> { IStateSpace<State, Action> StateSpace { get; } } An IAction, would be to move up(this is, if in (2, 2) move to (2, 1)), move down, etc. Now, I'll want that each action has access to a StateSpace so it can do some checking logic. Is this implementation correct? Or is this a bad case of a circular dependence? If yes, how to accomplish "the same" in a different way? Thanks

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  • how would I call/use Subsonic from within a WinForms app being deployed over clickonce (with Sqlite

    - by Greg
    Hi, Background - I need a framework/approach to managed database updates for a .NET Winforms app being deployed on users PC's via clickonce deploy. The app uses a sqlite database. Q1. What mechanism does Subsonic use to run such migrations on the local PC? e.g. would it be MSBuild Q2. If it does need a tool like how can my application robustly kick off MsBuild? i.e. how can it be sure what path it is installed, what if it is not installed, should I be including the MSBuild.exe in the clickonce package so that I know it is there for sure myself? Q3. Any other suggestions on how to use Subsonic in this specific use case? Q4. Any comments on whether MigratorDotNet would be a better fit? (if someone has had experience with both) Q5. Could I use subsonic's bare migration framework and just have a set of SQL files to do the upgrade/downgrade? i.e. just use the framework to check database version and which scripts to run etc?

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  • Can this auto-stretcing scenario be realized undex XHTML/CSS?

    - by Vilx-
    I want two horizontal areas in my webpage. The first one is the menu. It's on the top. Unfortunately I don't know its size, and it might change in response to user actions. Below the menu is the main area which should stretch at least as far as the bottom of the window (if there is little content) or beyond (if there is a lot of content. To illustrate with ASCII art: +----------------------------------------------------+ | This area resizes vertically depending on contents | +----------------------------------------------------+ | This area stretches to the bottom of the window, | | but can be even larger if necessary. Note: this | | should be a separate area because it will contain | | children with height:100% as well. | | | +----------------------------------------------------+ Can this be done? Can it be done with Javascript? Added: To put things in perspective and avoid confusion, think of it this way: the top menu is generated by myself, but the bottom area is an IFrame which I want to fill the rest of the page. This is what it eventually comes down to anyway in my case.

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  • Excess errors on model from somewhere

    - by gmile
    I have a User model, and use an acts_as_authentic (from authlogic) on it. My User model have 3 validations on username and looks as following: User < ActiveRecord::Base acts_as_authentic validates_presence_of :username validates_length_of :username, :within => 4..40 validates_uniqueness_of :username end I'm writing a test to see my validations in action. Somehow, I get 2 errors instead of one when validating a uniqueness of a name. To see excess error, I do the following test: describe User do before(:each) do @user = Factory.build(:user) end it "should have a username longer then 3 symbols" do @user2 = Factory(:user) @user.username = @user2.username @user.save puts @user.errors.inspect end end I got 2 errors on username: @errors={"username"=>["has already been taken", "has already been taken"]}. Somehow the validation passes two times. I think authlogic causes that, but I don't have a clue on how to avoid that. Another case of problem is when I set username to nil. Somehow I get four validation errors instead of three: @errors={"username"=>["is too short (minimum is 3 characters)", "should use only letters, numbers, spaces, and .-_@ please.", "can't be blank", "is too short (minimum is 4 characters)"]} I think authlogic is one that causes this strange behaviour. But I can't even imagine on how to solve that. Any ideas?

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  • Read IFrame content using JavaScript

    - by Rajat
    Ok, This is my first time dealing seriously with IFrames and I cant seem to understand a few things: First the sample code I am testing with: <head> <script type="text/javascript"> function init(){ console.log("IFrame content: " + window.frames['i1'].document.getElementsByTagName('body')[0].innerHTML); } </script> </head> <body onload="init();"> <iframe name="i1" src="foo.txt"/> </body> the file "foo.txt" looks like this: sample text file Questions: 1) The iframe seems to be behaving as a HTML document and the file text is actually part of the body instead. Why ? Is it a rule for an IFrame to be a HTML document. Is it not possible for the content of an iframe to be just plain text ?? 2) The file content gets wrapped inside a pre tag for some reason. Why is this so ? Is it always the case? 3) My access method in the javascript is working but is there any other alternative? [native js solutions please] If the content is wrapped in a pre tag always then I will actually have to lookup inside the pre tag rather than lookup the innerHTML

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  • After Delete Trigger Fires Only After Delete?

    - by Brandi
    I thought "after delete" meant that the trigger is not fired until after the delete has already taken place, but here is my situation... I made 3, nearly identical SQL CLR after delete triggers in C#, which worked beautifully for about a month. Suddenly, one of the three stopped working while an automated delete tool was run on it. By stopped working, I mean, records could not be deleted from the table via client software. Disabling the trigger caused deletes to be allowed, but re-enabling it interfered with the ability to delete. So my question is 'how can this be the case?' Is it possible the tool used on it futzed up the memory? It seems like even if the trigger threw an exception, if it is AFTER delete, shouldn't the records be gone? All the trigger looks like is this: ALTER TRIGGER [sysdba].[AccountTrigger] ON [sysdba].[ACCOUNT] AFTER DELETE AS EXTERNAL NAME [SQL_IO].[SQL_IO.WriteFunctions].[AccountTrigger] GO The CLR trigger does one select and one insert into another database. I don't yet know if there are any errors from SQL Server Mgmt Studio, but will update the question after I find out.

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  • How can i use a commandlinetool (ie. sox) via subprocess.Popen with mod_wsgi?

    - by marue
    I have a custom django filefield that makes use of sox, a commandline audiotool. This works pretty well as long as i use the django development server. But as soon as i switch to the production server, using apache2 and mod_wsgi, mod_wsgi catches every output to stdout. This makes it impossible to use the commandline tool to evaluate the file, for example use it to check if the uploaded file really is an audio file like this: filetype=subprocess.Popen([sox,'--i','-t','%s'%self.path], shell=False,\ stdout=subprocess.PIPE, stderr=subprocess.PIPE) (filetype,error)=filetype.communicate() if error: raise EnvironmentError((1,'AudioFile error while determining audioformat: %s'%error)) Is there a way to workaround for this? edit the error i get is "missing filename". I am using mod_wsgi 2.5, standard with ubuntu 8.04. edit2 What exactly happens, when i call subprocess.Popen from within django in mod_wsgi? Shouldn't subprocess stdin/stdout be independent from django stdin/stdout? In that case mod_wsgi should not affect programms called via subprocess... I'm really confused right now, because the file i am trying to access is a temporary file, created via a filenamevariable that i pass to the file creation and the subprocess command. That file is being written to /tmp, where the rights are 777, so it can't be a rights issue. And the error message is not "file does not exist", but "missing filename", which suggests i am not passing a filename as parameter to the commandlinetool.

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  • How to handle image/gif type response on client side using GWT

    - by user200340
    Hi all, I have a question about how to handle image/gif type response on client side, any suggestion will be great. There is a service which responds for retrieving image (only one each time at the moment) from database. The code is something like, JDBC Connection Construct MYSQL query. Execute query If has ResultSet, retrieve first one { //save image into Blob image, “img” is the only entity in the image table. image = rs.getBlob("img"); } response.setContentType("image/gif"); //set response type InputStream in = image.getBinaryStream(); //output Blob image to InputStream int bufferSize = 1024; //buffer size byte[] buffer = new byte[bufferSize]; //initial buffer int length =0; //read length data from inputstream and store into buffer while ((length = in.read(buffer)) != -1) { out.write(buffer, 0, length); //write into ServletOutputStream } in.close(); out.flush(); //write out The code on client side .... imgform.setAction(GWT.getModuleBaseURL() + "serviceexample/ImgRetrieve"); .... ClickListener { OnClick, then imgform.submit(); } formHandler { onSubmit, form validation onSubmitComplete ??????? //handle response, and display image **Here is my question, i had tried Image img = new Image(GWT.getHostPageBaseURL() +"serviceexample/ImgRetrieve"); mg.setSize("300", "300"); imgpanel.add(img); but i only got a non-displayed image with 300X300 size.** } So, how should i handle the responde in this case? Thanks,

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  • PHP Commercial Project Function define

    - by Shiro
    Currently I am working with a commercial project with PHP. I think this question not really apply to PHP for all programming language, just want to discuss how your guys solve it. I work in MVC framework (CodeIgniter). all the database transaction code in model class. Previously, I seperate different search criteria with different function name. Just an example function get_student_detail_by_ID($id){} function get_student_detail_by_name($name){} as you can see the function actually can merge to one, just add a parameter for it. But something you are rushing with project, you won't look back previously got what similar function just make some changes can meet the goal. In this case, we found that there is a lot function there and hard to maintenance. Recently, we try to group the entity to one ultimate search something like this function get_ResList($is_row_count=FALSE, $record_start=0, $arr_search_criteria='', $paging_limit=20, $orderby='name', $sortdir='ASC') we try to make this function to fit all the searching criteria. However, our system getting bigger and bigger, the search criteria not more 1-2 tables. It require join with other table with different purpose. What we had done is using IF ELSE, if(bla bla bla) { $sql_join = JOIN_SOME_TABLE; $sql_where = CONDITION; } at the end, we found that very hard to maintance the function. it is very hard to debug as well. I would like to ask your opinion, what is the commercial solution they solve this kind of issue, how to define a function and how to revise it. I think this is link project management skill. Hope you willing to share with us. Thanks.

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  • Getting started with open source

    - by lola
    Hi all, I'm an undergraduate who has decided that he wants to join the open source community and contribute. However, I have come to think that, once you have chosen an open source project, a lot of time is spent in learning the nitty gritties of that project in addition to stuff like subversion,etc which a typical undergraduate isn't exposed to. So, you have to stick with that project for a long time, say a year or two, before moving on to other projects. In this case, choosing the right(for you) initial project is very important since if you choose one,and say, the development in your field of interest(in that project) is a low priority and not exciting enough, you'll lose interest and stop contributing to open source all together. So what I wanted to know was, since there are thousands of open source projects, is all this being documented somewhere with tags,etc so that a beginner can choose his projects. The GSoc 2010 ideas list is a great starting point, but it only covers a handful. Hence, I thought why not ask this at stackoverflow: if you have any pointers as to where to start, when choosing a FOSS project or any other tips related to starting with FOSS. P.S. I'm interested in projects involving mobile ad hoc networks(those using TinyOS, preferably), so pointers related to these will be great. I'm looking through Freifunk and OLPC as of now, needed more ideas.

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  • Is it possible to have asynchronous processing

    - by prashant2361
    Hi, I have a requirement where I need to send continuous updates to my clients. Client is browser in this case. We have some data which updates every sec, so once client connects to our server, we maintain a persistent connection and keep pushing data to the client. I am looking for suggestions of this implementation at the server end. Basically what I need is this: 1. client connects to server. I maintain the socket and metadata about the socket. metadata contains what updates need to be send to this client 2. server process now waits for new client connections 3. One other process will have the list of all the sockets opened and will go through each of them and send the updates if required. Can we do something like this in Apache module: 1. Apache process gets the new connection. It maintains the state for the connection. It keeps the state in some global memory and returns back to root process to signify that it is done so that it can accept the new connection 2. the Apache process though has returned the status to root process but it is also executing in parallel where it going through its global store and sending updates to the client, if any. So can a Apache process do these things: 1. Have more than one connection associated with it 2. Asynchronously waiting for new connection and at the same time processing the previous connections? Regards Prashant

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  • CORBA on MacOS X (Cocoa)

    - by user8472
    I am currently looking into different ways to support distributed model objects (i.e., a computational model that runs on several different computers) in a project that initially focuses on MacOS X (using Cocoa). As far as I know there is the possibility to use the class cluster around NSProxy. But there also seem to be implementations of CORBA around with Objective-C support. At a later time there may be the need to also support/include Windows machines. In that case I would need to use something like Gnustep on the Windows side (which may be an option, if it works well) or come up with a combination of both technologies. Or write something manually (which is, of course, the least desirable option). My questions are: If you have experience with both technologies (Cocoa native infrastructure vs. CORBA) can you point out some key features/issues of either approach? Is it possible to use Gnustep with Cocoa in the way explained above? Is it possible (and reasonably feasible, i.e. simpler than writing a network layer manually) to communicate among all MacOS clients using Cocoa's technology and with Windows clients through CORBA?

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  • Most efficient method of detecting/monitoring DOM changes?

    - by Graza
    I need an efficient mechanism for detecting changes to the DOM. Preferably cross-browser, but if there's any efficient means which are not cross browser, I can implement these with a fail-safe cross browser method. In particular, I need to detect changes that would affect the text on a page, so any new, removed or modified elements, or changes to inner text (innerHTML) would be required. I don't have control over the changes being made (they could be due to 3rd party javascript includes, etc), so it can't be approached from this angle - I need to "monitor" for changes somehow. Currently I've implemented a "quick'n'dirty" method which checks body.innerHTML.length at intervals. This won't of course detect changes which result in the same length being returned, but in this case is "good enough" - the chances of this happening are extremely slim, and in this project, failing to detect a change won't result in lost data. The problem with body.innerHTML.length is that it's expensive. It can take between 1 and 5 milliseconds on a fast browser, and this can bog things down a lot - I'm also dealing with a large-ish number of iframes and it all adds up. I'm pretty sure the expensiveness of doing this is because the innerHTML text is not stored statically by browsers, and needs to be calculated from the DOM every time it is read. The types of answers I am looking for are anything from the "precise" (for example event) to the "good enough" - perhaps something as "quick'n'dirty" as the innerHTML.length method, but that executes faster.

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  • How to output multicolumn html without "widows"?

    - by user314850
    I need to output to HTML a list of categorized links in exactly three columns of text. They must be displayed similar to columns in a newspaper or magazine. So, for example, if there are 20 lines total the first and second columns would contain 7 lines and the last column would contain 6. The list must be dynamic; it will be regularly changed. The tricky part is that the links are categorized with a title and this title cannot be a "widow". If you have a page layout background you'll know that this means the titles cannot be displayed at the bottom of the column -- they must have at least one link underneath them, otherwise they should bump to the next column (I know, technically it should be two lines if I were actually doing page layout, but in this case one is acceptable). I'm having a difficult time figuring out how to get this done. Here's an example of what I mean: Shopping Link 3 Link1 Link 1 Link 4 Link2 Link 2 Link 3 Link 3 Cars Link 1 Music Games Link 2 Link 1 Link 1 Link 2 News As you can see, the "News" title is at the bottom of the middle column, and so is a "widow". This is unacceptable. I could bump it to the next column, but that would create an unnecessarily large amount of white space at the bottom of the second column. What needs to happen instead is that the entire list needs to be re-balanced. I'm wondering if anyone has any tips for how to accomplish this, or perhaps source code or a plug in. Python is preferable, but any language is fine. I'm just trying to get the general concept down.

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  • Why are my connections not closed even if I explicitly dispose of the DataContext?

    - by Chris Simpson
    I encapsulate my linq to sql calls in a repository class which is instantiated in the constructor of my overloaded controller. The constructor of my repository class creates the data context so that for the life of the page load, only one data context is used. In my destructor of the repository class I explicitly call the dispose of the DataContext though I do not believe this is necessary. Using performance monitor, if I watch my User Connections count and repeatedly load a page, the number increases once per page load. Connections do not get closed or reused (for about 20 minutes). I tried putting Pooling=false in my config to see if this had any effect but it did not. In any case with pooling I wouldn't expect a new connection for every load, I would expect it to reuse connections. I've tried putting a break point in the destructor to make sure the dispose is being hit and sure enough it is. So what's happening? Some code to illustrate what I said above: The controller: public class MyController : Controller { protected MyRepository rep; public MyController () { rep = new MyRepository(); } } The repository: public class MyRepository { protected MyDataContext dc; public MyRepository() { dc = getDC(); } ~MyRepository() { if (dc != null) { //if (dc.Connection.State != System.Data.ConnectionState.Closed) //{ // dc.Connection.Close(); //} dc.Dispose(); } } // etc } Note: I add a number of hints and context information to the DC for auditing purposes. This is essentially why I want one connection per page load

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  • Go - Using a map for its set properties with user defined types

    - by Seth Hoenig
    I'm trying to use the built-in map type as a set for a type of my own (Point, in this case). The problem is, when I assign a Point to the map, and then later create a new, but equal point and use it as a key, the map behaves as though that key is not in the map. Is this not possible to do? // maptest.go package main import "fmt" func main() { set := make(map[*Point]bool) printSet(set) set[NewPoint(0, 0)] = true printSet(set) set[NewPoint(0, 2)] = true printSet(set) _, ok := set[NewPoint(3, 3)] // not in map if !ok { fmt.Print("correct error code for non existent element\n") } else { fmt.Print("incorrect error code for non existent element\n") } c, ok := set[NewPoint(0, 2)] // another one just like it already in map if ok { fmt.Print("correct error code for existent element\n") // should get this } else { fmt.Print("incorrect error code for existent element\n") // get this } fmt.Printf("c: %t\n", c) } func printSet(stuff map[*Point]bool) { fmt.Print("Set:\n") for k, v := range stuff { fmt.Printf("%s: %t\n", k, v) } } type Point struct { row int col int } func NewPoint(r, c int) *Point { return &Point{r, c} } func (p *Point) String() string { return fmt.Sprintf("{%d, %d}", p.row, p.col) } func (p *Point) Eq(o *Point) bool { return p.row == o.row && p.col == o.col }

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  • Weird MySQL behavior, seems like a SQL bug

    - by Daniel Magliola
    I'm getting a very strange behavior in MySQL, which looks like some kind of weird bug. I know it's common to blame the tried and tested tool for one's mistakes, but I've been going around this for a while. I have 2 tables, I, with 2797 records, and C, with 1429. C references I. I want to delete all records in I that are not used by C, so i'm doing: select * from i where id not in (select id_i from c); That returns 0 records, which, given the record counts in each table, is physically impossible. I'm also pretty sure that the query is right, since it's the same type of query i've been using for the last 2 hours to clean up other tables with orphaned records. To make things even weirder... select * from i where id in (select id_i from c); DOES work, and brings me the 1297 records that I do NOT want to delete. So, IN works, but NOT IN doesn't. Even worse: select * from i where id not in ( select i.id from i inner join c ON i.id = c.id_i ); That DOES work, although it should be equivalent to the first query (i'm just trying mad stuff at this point). Alas, I can't use this query to delete, because I'm using the same table i'm deleting from in the subquery. I'm assuming something in my database is corrupt at this point. In case it matters, these are all MyISAM tables without any foreign keys, whatsoever, and I've run the same queries in my dev machine and in the production server with the same result, so whatever corruption there might be survived a mysqldump / source cycle, which sounds awfully strange. Any ideas on what could be going wrong, or, even more importantly, how I can fix/work around this? Thanks! Daniel

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  • VB.NET: Dialog exits when enter pressed?

    - by Camilo Martin
    Hi all; My problem seems to be quite simple, but it's not working the intuitive way. I'm designing a Windows Forms Application, and there is a dialog that should NOT exit when the enter key is pressed, instead it has to validate data first, in case enter was pressed after changing the text of a ComboBox. I've tried by telling it what to do on KeyPress event of the ComboBox if e is the Enter key: Private Sub ComboBoxSizeChoose_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles ComboBoxSizeChoose.KeyPress If e.KeyChar = Convert.ToChar(Keys.Enter) Then Try TamanhoDaNovaFonte = Single.Parse(ComboBoxSizeChoose.Text) Catch ex As Exception Dim Dialogo2 As New Dialog2 Dialog2.ShowDialog() ComboBoxSizeChoose.Text = TamanhoDaNovaFonte End Try End If End Sub But no success so far. When the Enter key is pressed, even with the ComboBox on focus, the whole dialog is closed, returning to the previous form. The validation is NOT done at all, and it has to be done before exiting. In fact, I don't even want to exit on the form's enter KeyPress, the only purpose of the enter key on the whole dialog is to validate the ComboBox (but only when in focus, for the sake of an intuitive UI). I've also tried appending the validation to the KeyPress event of the whole dialog's form, if the key is Enter. NO SUCCESS! It's like my code wasn't there at all. What should I do? (Visual Studio 2008, VB.NET)

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  • how do use Ninject with class libraries I am developing?

    - by Greg
    Hi, If I am working on a class library how do I make use of Ninject here? Ie from the internal class library point of view and also from the client code? For example: should the class library have it's own IOC set up, or should it always assume the client code will supply? if no (ie it's upto the client to have the IOC in place) then where is the mapping data stored here'. Is this mapping of the class library's functionality to be places in the client? have a reusable library that is available, that uses interfaces with classes that use the getInstance concept to create concrete classes for you to use, then in this case would that make sense on the client side to use the IOC container to create instances of these classes? Or is that really applying a double layer of abstraction? Q2 Or in the cases where I'm building the reusable library myself and want the client to use an IOC container, then in my reusable library would I then dispense with any overhead of having factories or "getInstance" methods to instantiate the classes in the client? (i.e. as the IOC container would do this no?)

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  • javascript error handeling

    - by pankaj
    I have a javascript function for checking errors which i am callin on OnClicentClick event of a button. Once it catch a error i want to stop execution of click event . But in my case it always it always executes the onclick event. Following is my function: function DisplayError() { if (document.getElementById('<%=txtPassword.ClientID %>').value.length < 6 || document.getElementById('<%=txtPassword.ClientID %>').value.length > 12) { document.getElementById('<%=lblError.ClientID %>').innerText = "Password length must be between 6 to 12 characters"; return false; } var str = <%=PhoneNumber()%>; if(str.length <10) { alert('<%=phoneNum%>'.length); document.getElementById('<%=lblError.ClientID %>').innerText = "Phone Number not in correct format"; return false; } } button html code: <asp:Button runat="server" Text="Submit" ID="btnSubmit" ValidationGroup="submit" onclick="btnSubmit_Click" OnClientClick="DisplayError()"/> It should not execute the button click event once it satisfies any of the IF condition in javascript function.

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  • Image overlapping in widget

    - by Hunt
    I am trying to create a widget in android in which when I click over image the image gets changed with a new one -- kind of toggle image. But when I click over it, the image overwrites over the old one rather then replacing the new one. I don't know whether this is the way the widget works or am I doing something wrong. My images are semi-transparent so in case one overrides another one can see the image which is being overlapped. This is the code that I have written in OnReceive by overriding it: @Override public void onReceive(Context context, Intent intent){ if (intent.getAction().equals(iAlertConstant.ACTION_WIDGET_UPDATE_FROM_WIDGET)) { RemoteViews remoteViews = new RemoteViews(context.getPackageName(),R.layout.mywidget); remoteViews.setImageViewResource(R.id.btnOnOff,R.drawable.offbtn); ComponentName thisWidget = new ComponentName(context, EmergencyWidget.class); AppWidgetManager.getInstance(context).updateAppWidget(thisWidget, remoteViews); } else super.onReceive(context, intent); } Layout <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:background="@drawable/widget_background" android:paddingLeft="10.0dip" android:paddingTop="8.0dip" android:paddingRight="10.0dip" android:paddingBottom="8.0dip" android:layout_width="fill_parent" android:layout_height="72dp" android:layout_marginLeft="10.0dip" android:layout_marginTop="10.0dip" android:layout_marginRight="10.0dip" android:id="@+id/emergencyWidget" android:orientation="horizontal"> <ImageView android:background="@drawable/offbtn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginTop="7dp" android:layout_marginLeft="4dp" android:layout_marginRight="4dp" android:layout_gravity="right" android:id="@+id/btnOnOff" /> </LinearLayout>

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  • Do variable references (alias) incure runtime costs in c++?

    - by cheshirekow
    Maybe this is a compiler specific thing. If so, how about for gcc (g++)? If you use a variable reference/alias like this: int x = 5; int& y = x; y += 10; Does it actually require more cycles than if we didn't use the reference. int x = 5; x += 10; In other words, does the machine code change, or does the "alias" happen only at the compiler level? This may seem like a dumb question, but I am curious. Especially in the case where maybe it would be convenient to temporarily rename some member variables just so that the math code is a little easier to read. Sure, we're not exactly talking about a bottleneck here... but it's something that I'm doing and so I'm just wondering if there is any 'actual' difference... or if it's only cosmetic.

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  • List of Big-O for PHP functions?

    - by Kendall Hopkins
    After using PHP for a while now, I've noticed that not all PHP built in functions as fast as expected. Consider the below two possible implementations of a function that finds if a number is prime using a cached array of primes. //very slow for large $prime_array $prime_array = array( 2, 3, 5, 7, 11, 13, .... 104729, ... ); $result_array = array(); foreach( $array_of_number => $number ) { $result_array[$number] = in_array( $number, $large_prime_array ); } //still decent performance for large $prime_array $prime_array => array( 2 => NULL, 3 => NULL, 5 => NULL, 7 => NULL, 11 => NULL, 13 => NULL, .... 104729 => NULL, ... ); foreach( $array_of_number => $number ) { $result_array[$number] = array_key_exists( $number, $large_prime_array ); } This is because in_array is implemented with a linear search O(n) which will linearly slow down as $prime_array grows. Where the array_key_exists function is implemented with a hash lookup O(1) which will not slow down unless the hash table gets extremely populated (in which case it's only O(logn)). So far I've had to discover the big-O's via trial and error, and occasionally looking at the source code. Now for the question... I was wondering if there was a list of the theoretical (or practical) big O times for all* the PHP built in functions. *or at least the interesting ones For example find it very hard to predict what the big O of functions listed because the possible implementation depends on unknown core data structures of PHP: array_merge, array_merge_recursive, array_reverse, array_intersect, array_combine, str_replace (with array inputs), etc.

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  • How to pass data from selected rows using checkboxes from JSP to the server

    - by eddy
    Hi, I'd like to know if there's any way to send data to the server for the selected rows using the checkboxes I've put on those rows? I mean , how can I send only the data (in this case mileage ) of those selected rows (selected with the checkboxes) to the server ? see the image Here's the html code I use: <table> <thead> <tr class="tableheader"> <td width="10%"></td> <td width="30%">Vehicle</td> <td width="40%">Driver</td> <td width="10%">Mileage</td> </tr> </thead> <tbody> <c:forEach items="${list}" var="item"> <tr> <td align="center"> <input type="checkbox" name="selectedItems" value="c:out value="${item.numberPlate}"/>"/> </td> <td align="left"><c:out value="${item.numberPlate}"/></td> <td align="left"><c:out value="${item.driver.fullName}" /></td> <td align="left"><input type="text" name="mileage" value="" /></td> </tr> </c:forEach> </tbody> </table> I really hope you can give some guidance on this. Thanks in beforehand.

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  • Protecting Content with AuthLogic

    - by Rob Wilkerson
    I know this sounds like a really, really simple use case and I'm hoping that it is, but I swear I've looked all over the place and haven't found any mention of any way - not even the best way - of doing this. I'm brand-spanking new to Ruby, Rails and everything surrounding either (which may explain a lot). The dummy app that I'm using as my learning tool requires authentication in order to do almost anything meaningful, so I chose to start by solving that problem. I've installed the AuthLogic gem and have it working nicely to the extent that is covered by the intro documentation and Railscast, but now that I can register, login and logout...I need to do something with it. As an example, I need to create a page where users can upload images. I'm planning to have an ImagesController with an upload action method, but I want that only accessible to logged in users. I suppose that in every restricted action I could add code to redirect if there's no current_user, but that seems really verbose. Is there a better way of doing this that allows me to define or identify restricted areas and handle the authentication check in one place?

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