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  • Efficient algorithm for Next button on a MySQL result set

    - by David Grayson
    I have a website that lets people view rows in a table (each row is a picture). There are more than 100,000 rows. You can view different subsets of the rows, and you can view them with different sort orders. While you are viewing one of the rows, you can click the "Next" or "Previous" buttons to go the next/previous row in the list. How would you implement the "Next" and "Previous" features of the website? More specifically, if you have an arbitrary query that returns a list of up to 100,000+ rows, and you know some information about the current row someone is viewing, how do you determine the NEXT row efficiently? Here is the pseudo-code of the solution I came up with when the website was young, and it worked well when there were only 1000 rows, but now that there are 100,000 rows I think it is eating up too much memory. int nextRowId(string query, int currentRowId) { array allRowIds = mysql_query(query); // Takes up a lot of memory! int currentIndex = (index of currentRowId in allRowIds); // Takes time! return allRowIds[currentIndex+1]; } While you are thinking about this problem, remember that the website can store more information about the current row than just its ID (for example, the position of the current row in the result set), and this information can be used as a hint to help determine the ID of the next row. Edit: Sorry for not mentioning this earlier, but this isn't just a static website: rows can often be added to the list, and rows can be re-ordered in the list. (Much rarer, rows can be removed from the list.) I think that I should worry about that kind of thing, but maybe you can convince me otherwise.

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  • What is the best way to have a dynamic dropdownlist in PHP and POST selected value

    - by mouthpiec
    Hi, I am writing the following in PHP: i would like to have 2 dropdownlists, where the second one is populated from a mySQL dB according to the choice made on the first dropdown list. Then I would like to use the values of the selected values of the dropdownlist to call another PHP page in which I will generate a db query. Eg: List A: Car Manufactures (honda, nissan, etc) List B: Models (accord, civic, etc) Then I will have a submit button, to POST the values in another PHP file? (I have the basics of how to perform the above without having a dynamic list, but I tried this with AJAX, but I am having problems to pass the value of the second dropdownlist) Any tips of how I can perform the above?

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  • .each or search function, how can I make use of those?

    - by Noor
    I have a ul list, with 10 items, and I have a label that displays the selected li text. When I click a button, I need to check the label, versus all the list items to find the matching one, when it finds that I need to assign the corresponding number. I.e. list: Messi Cristiano Zlatan hidden values of list items: www.messi.com www.cronaldo.com www.ibra.com label: Zlatan script (thought)procces: get label text, search list for matching string, get the value of that string. (and if someone could point me in a direction to learn these basic(?) stuff. tried to be as specific as possible, thanks guys! edit: really sorry for not being clear. the li's are all getting a class dynamically (.listitem). the links can be stored in an array or in a hidden field (or other ul thats hidden) it doesn't really matter where the links are.. $('.listitem').click(function() { $("#elname").text($(this).text()); $("#such").attr("href", $(this).attr('value')); }); I was trying that with the li's having values but I realized that li's can't have values.. thanks again!

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  • Set Pivot Items from Cell Range? Excel 2007

    - by Ben
    I have developed code which identifies the multiple item selections from a Pivot field and writes the list of items to a table. I then wish to take this contents of the list and use it to populate a number of other Pivot Tables on other tabs. I currently have the ability to do this for single Pivot items selections, but I need to do this for multiple selections. If I select multiple items in the Pivot Table and attempt to pass these selections to the other Pivot Tables it creates an error because it sees only hte text "Multiple Items" instead of a list of each item that was checked in the upstream Pivot field. I need some VBA code that allows me to use the list to set another Pivot Field's selections. All the Pivot fields in question here are page fields. I am using Excel 2007. Any help is appreciated. Thanks!

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  • js regex replace multiple words

    - by Raghav
    I need to replace ${conferance name} with ABC, ${conference day} with Monday in the following sentence. Could some one help me with the regex. var text = "<td>${conference name}</td><td>${conference day}</td>" var list = ["${conferance name}", "${conference day}" ] for (var j = 1; j < list.length; j++) { //Extracting the col name var colName = list[j].split("${"); colName = colName.split("}")[0]; //Replacing the col name text = text.replace(new RegExp('\\$\\{' + colName + '\\}', 'g'), "ABC"); } The above code repalces fine if i have ${conference_name}, but it fails when i have a space in between. The list is a dynamic array. And the Replace statements are also dynamic. I just simulated them as objects here for fitting them in the Regex Statement. Thanks in Advance.

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  • What are the best possible ways to benchmark RAM (no-ECC) under linux / arm?

    - by moul
    I want to test integrity and global performances of no-ECC memory chips on a custom board Are there some tools that run under linux so I can monitor system and global temperature in the same time ? Are there some no-ECC specific tests to do in general ? EDIT 1: I already know how to monitor temperature (I use a special platform feature /sys/devices/platform/......../temp1_input). For now : wazoox : it works but I've to code my own tests Jason Huntley : ramspeed : does not work on arm stream benchmark : it works and is very fast, so I'll look if it's accurate and complete memtest : I'll try later, since it does not run directly from linux stress for fedora : I'll try later too, it's too problematic for me to install fedora now I found this distribution : http://www.stresslinux.org/sl/ I'll continue to check tools that run directly under linux without too big dependencies, after I'll maybe give a try to solutions like stresslinux, memtest, stress for fedora. Thanks for you answers, I'll continue to investigate

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  • Like query ing LINQ to Object

    - by Pankaj
    Hello All i have a US states list List<string> state // contain all 51 US states Now i have a string which contain some text like okl (it means Oklahoma for me). what i want i want 'like' query in List state and get Oklahoma state.

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  • Few iPhone noob questions

    - by mshsayem
    Why should I declare local variables as 'static' inside a method? Like: static NSString *cellIdentifier = @"Cell"; Is it a performance advantage? (I know what 'static' does; in C context) What does this syntax mean?[someObj release], someObj = nil; Two statements? Why should I assign nil again? Is not 'release' enough? Should I do it for all objects I allocate/own? Or for just view objects? Why does everyone copy NSString, but retains other objects (in property declaration)? Yes, NSStrings can be changed, but other objects can be changed also, right? Then why 'copy' for just NSString, not for all? Is it just a defensive convention? Shouldn't I release constant NSString? Like here:NSString *CellIdentifier = @"Cell"; Why not? Does the compiler allocate/deallocate it for me? In some tutorial application I observed these (Built with IB): Properties(IBOutlet, with same ivar name): window, someLabel, someTextField, etc etc... In the dealloc method, although the window ivar was released, others were not. My question is: WHY? Shouldn't I release other ivars(labels, textField) as well? Why not? Say, I have 3 cascaded drop-down lists. I mean, based on what is selected on the first list, 2nd list is populated and based on what is selected on the second list, 3rd list is populated. What UI components can reflect this best? How is drop-down list presented in iPhone UI? Tableview with UIPicker? When should I update the 2nd, 3rd list? Or just three labels which have touch events? Can you give me some good example tutorials about Core-Data? (Not just simple data fetching and storing on 2/3 tables with 1/2 relationship) How can I know whether my app is leaking memory? Any tools?

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  • HTML E-Mail as fileattachment

    - by johnny
    I have a Problem with Outlook 2010. I sent an E-Mail with a Contactform with this Code: $message = ' <html> <head> <title>Anfrage ('.$cfg->get('global.page.title').')</title> <style type="text/css"> body { background:#FFFFFF; color:#000000; } #tbl td { background:#F0F0F0; vertical-align:top; } #tbl2 td { background:#E0E0E0; vertical-align:top; } </style> </head> <body> <p>Mail von der Webseite '.$cfg->get('global.page.title').'</p> <table id="tbl"> <tr> <td>Absender</td> <td>'.htmlspecialchars($_POST['name']).' ('.htmlspecialchars(trim($_POST['email'])).')</td> </tr> <tr id="tbl2"> <td>Betreff:</td> <td>'.htmlspecialchars($_POST["topic"]).'</td> </tr> <tr> <td>Nachricht:</td> <td>'.nl2br(htmlspecialchars($_POST["message"])).'</td> </tr> </table> </body> </html>'; $absender = $_POST['name'].' <'.$_POST['email'].'>'; $header = "From: $absender\n"; $header .= "Reply-To: $absender\n"; $header .= "X-Mailer: PHP/" . phpversion(). "\n"; $header .= "X-Sender-IP: " . $_SERVER["REMOTE_ADDR"] . "\n"; $header .= "Content-Type: text/html; Charset=utf-8"; $send_mail = mail($cfg->get('contact.toMailAdress'), "Anfrage (".$cfg->get('global.page.title').")", $message, $header); //$send_mail = mail("[email protected]", "Anfrage (".$cfg->get('global.page.title').")", $message, $header); $_SESSION['kontakt_form_time'] = time(); $tpl->assign("mail_sent", $send_mail); When I sent the email, doesn't shows the message. it generates a File named [NAME].h. The Message is in this File. How can I fix that, that the message shows in the E-Mail. Is this a Problem about the settings in Outlook?

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  • Process-to-port mapping with SNMP and/or wmi/wmic in java

    - by Niddy888
    I'm trying to use SNMP to map outgoing ports on my host computer with the application running on the computer that is responsible for that communication. When running "netstat -ano" I get access to Protocol, Local Address (with port), Foreign Address (with port), State and PID. But I want to do this entirely without having to execute "cmd" from Java. By using SNMP OID: .1.3.6.1.2.1.25.4 (.iso.org.dod.internet.mgmt.mib-2.host.hrSWRun) I get access to PID (ex. 1704), Name (ex. cmd.exe), Path (ex. C:\Windows\system32) among others. There is an SNMP OID: .1.3.6.1.2.1.6.13 (.iso.org.dod.internet.mgmt.mib-2.tcp.tcpConnTable) that give you access to TCP connection state, local address, local port, remote address, remote port. But NO PID. So to sum up. My question again: Is there a way to "map" these tables together? Either directly in SNMP with other OID's or in conjunction with WMI / WMIC?

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  • onCommand on button not firing inside gridView??

    - by sah302
    This is really driving me crazy. I've got a button inside a gridview to remove that item from the gridview (its datasource is a list). I've got the list being saved to session anytime a change is being made to it, and on page_load check if that session variable is empty, if not, then set that list to bind to the gridview. Code Behind: Public accomplishmentTypeDao As New AccomplishmentTypeDao() Public accomplishmentDao As New AccomplishmentDao() Public userDao As New UserDao() Public facultyDictionary As New Dictionary(Of Guid, String) Public facultyList As New List(Of User) Public associatedFaculty As New List(Of User) Public facultyId As New Guid Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load 'If Not Session("associatedFaculty") Is Nothing Then' ' Dim associatedFacultyArray As User() = DirectCast(Session("associatedFaculty"), User())' ' associatedFaculty = associatedFacultyArray.ToList()' 'End If' Page.Title = "Add a New Faculty Accomplishment" ddlAccomplishmentType.DataSource = accomplishmentTypeDao.getEntireTable() ddlAccomplishmentType.DataTextField = "Name" ddlAccomplishmentType.DataValueField = "Id" ddlAccomplishmentType.DataBind() facultyList = userDao.getListOfUsersByUserGroupName("Faculty") For Each faculty As User In facultyList facultyDictionary.Add(faculty.Id, faculty.LastName & ", " & faculty.FirstName) Next If Not Page.IsPostBack Then ddlFacultyList.DataSource = facultyDictionary ddlFacultyList.DataTextField = "Value" ddlFacultyList.DataValueField = "Key" ddlFacultyList.DataBind() End If gvAssociatedUsers.DataSource = associatedFaculty gvAssociatedUsers.DataBind() End Sub Protected Sub deleteUser(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.CommandEventArgs) facultyId = New Guid(e.CommandArgument.ToString()) associatedFaculty.Remove(associatedFaculty.Find(Function(user) user.Id = facultyId)) Session("associatedFaculty") = associatedFaculty.ToArray() gvAssociatedUsers.DataBind() upAssociatedFaculty.Update() End Sub Protected Sub btnAddUser_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnAddUser.Click facultyId = New Guid(ddlFacultyList.SelectedValue) associatedFaculty.Add(facultyList.Find(Function(user) user.Id = facultyId)) Session.Add("associatedFaculty", associatedFaculty.ToArray()) gvAssociatedUsers.DataBind() upAssociatedFaculty.Update() End Sub Protected Sub Delete(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.CommandEventArgs) End Sub End Class Markup: <asp:UpdatePanel ID="upAssociatedFaculty" runat="server" UpdateMode="Conditional"> <ContentTemplate> <p><b>Created By:</b> <asp:Label ID="lblCreatedBy" runat="server"></asp:Label></p> <p><b>Accomplishment Type: </b><asp:DropDownList ID="ddlAccomplishmentType" runat="server"></asp:DropDownList></p> <p><b>Accomplishment Applies To: </b><asp:DropDownList ID="ddlFacultyList" runat="server"></asp:DropDownList> &nbsp;<asp:Button ID="btnAddUser" runat="server" Text="Add Faculty" OnClientClick="incrementCounter();" /></p> <p> <asp:GridView ID="gvAssociatedUsers" runat="server" AutoGenerateColumns="false" GridLines="None" ShowHeader="false"> <Columns> <asp:BoundField DataField="Id" HeaderText="Id" Visible="False" /> <asp:TemplateField ShowHeader="False"> <ItemTemplate> <span style="margin-left: 15px;"> <p><%#Eval("LastName")%>, <%#Eval("FirstName")%> <asp:Button ID="btnUnassignUser" runat="server" CausesValidation="false" CommandArgument='<%# Eval("Id") %>' CommandName="Delete" OnCommand="deleteUser" Text='Remove' /></p> </span> </ItemTemplate> </asp:TemplateField> </Columns> <EmptyDataTemplate> <em>There are currently no faculty associated with this accomplishment.</em> </EmptyDataTemplate> </asp:GridView> </p> </ContentTemplate> </asp:UpdatePanel> Now here is the crazy part I am simply boggled by, if I uncomment the If Not Session... block of page_load, then deleteUser will never fire when btnUnassignUser is clicked. If I keep it commented out...it fires no problem, but then of course my list can never have more than one item since I am not loading the saved list from session into the gridview but just a fresh one. But the button click is being registered, because page_load is being stepped through again when I am viewing in debug mode, just deleteUser never fires. Why is this happening?? And how can I fix it??

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  • Pass Linq Expression to a function

    - by Kushan Hasithe Fernando
    I want to pass a property list of a class to a function. with in the function based on property list I'm going to generate a query. As exactly same functionality in Linq Select method. Here I'm gonna implement this for Ingress Database. As an example, in front end I wanna run a select as this, My Entity Class is like this public class Customer { [System.Data.Linq.Mapping.ColumnAttribute(Name="Id",IsPrimaryKey=true)] public string Id { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Name")] public string Name { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Address")] public string Address { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Email")] public string Email { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Mobile")] public string Mobile { get; set; } } I wanna call a Select function like this, var result = dataAccessService.Select<Customer>(C=>C.Name,C.Address); then,using result I can get the Name and Address properties' values. I think my Select function should looks like this, ( *I think this should done using Linq Expression. But im not sure what are the input parameter and return type. * ) Class DataAccessService { // I'm not sure about this return type and input types, generic types. public TResult Select<TSource,TResult>(Expression<Func<TSource,TResult>> selector) { // Here using the property list, // I can get the ColumnAttribute name value and I can generate a select query. } } This is a attempt to create a functionality like in Linq. But im not an expert in Linq Expressions. There is a project call DbLinq from MIT, but its a big project and still i couldn't grab anything helpful from that. Can someone please help me to start this, or can someone link me some useful resources to read about this.

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  • How to perform add/update of a model object that contains EntitySet

    - by David Liddle
    I have a similar concept to the SO questions/tags scenario however am trying to decide the best way of implementation. Tables Questions, QuestionTags and Tags Questions QuestionTags Tags --------- ------------ ---- QID QID TID QName TID TName When adding/updating a question I have 2 textboxes. The important part is a single textbox that allows users to enter in multiple Tags separated by spaces. I am using Linq2Sql so the Questions model has an EntitySet of QuestionTags with then link to Tags. My question is regarding the adding/updating of Questions (part 1), and also how to best show QuestionTags for a Question (part 2). Part 1 Before performing an add/update, my service layer needs to deal with 3 scenarios before passing to their respective repositories. Insert Tags that do not already exist Insert/Update Question Insert QuestionTags - when updating need to remove existing QuestionTags Here is my code below however started to get into a bit of a muddle. I've created extension methods on my repositories to get Tags WithNames etc. public void Add(Question q, string tags) { var tagList = tags.Split(new string[] { " " }, StringSplitOptions.RemoveEmptyEntries).ToList(); using (DB.TransactionScope ts = new DB.TransactionScope()) { var existingTags = TagsRepository.Get() .WithName(tagList) .ToList(); var newTags = (from t in tagList select new Tag { TName = t }).Except(existingTags, new TagsComparer()).ToList(); TagsRepository.Add(newTags); //need to insert QuestionTags QuestionsRepository.Add(q); ts.Complete(); } } Part 2 My second question is, when displaying a list of Questions how is it best to show their QuestionTags? For example, I have an Index view that shows a list of Questions in a table. One of the columns shows an image and when the user hovers over it shows the list of Tags. My current implementation is to create a custom ViewModel and show a List of QuestionIndexViewModel in the View. QuestionIndexViewModel { Question Question { get; set; } string Tags { get; set; } } However, this seems a bit clumsy and quite a few DB calls. public ViewResult Index() { var model= new List<QuestionIndexViewModel>(); //make a call to get a list of questions //foreach question make a call to get their QuestionTags, //to be able to get their Tag names and then join them //to form a single string. return View(model); } Also, just for test purposes using SQL Profiler, I decided to iterate through the QuestionTags entity set of a Question in my ViewModel however nothing was picked up in Profiler? What would be the reason for this?

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  • How to create a custom listview in android

    - by kaibuki
    Hi All, I want to create a list view custom like this link : http://sites.google.com/site/androideyecontact/_/rsrc/1238086823282/Home/android-eye-contact-lite/eye_contact-list_view_3.png?height=420&width=279 so far I have made a list view with text, and I am not extending list Activity, but I am extending Activity only. please if someone can provide me with a code for this. Thanks alot Cheers Kai

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  • Testing a (big) collection retrieved from a db

    - by Bas
    I'm currently doing integration testing on a live database and I have the following sql statement: var date = DateTime.Parse("01-01-2010 20:30:00"); var result = datacontext.Repository<IObject>().Where(r => r.DateTime > date).First(); Assert.IsFalse(result.Finished); I need to test if the results retrieved from the statement, where the given date is less then the date of the object, have Finished set to False. I do not know how many results I get back and currently I'm getting the first object of the list and check if that object has Finished set to false. I know testing only the first item of the list is not valid testing, as a solution for that I could iterate through the list and check all items on Finished, but putting logic in a Test is kinda going against the concept of writing 'good' tests. So my question is: Does anyone have a good solution of how to properly test the results of this list?

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  • Implicit Type Conversions in Reflection

    - by bradhe
    So I've written a quick bit of code to help quickly convert between business objects and view models. Not to pimp my own blog, but you can find the details here if you're interested or need to know. One issue I've run in to is that I have a custom collection type, ProductCollection, and I need to turn that in to a string[] in on my model. Obviously, since there is no default implicit cast, I'm getting an exception in my contract converter. So, I thought I would write the next little bit of code and that should solve the problem: public static implicit operator string[](ProductCollection collection) { var list = new List<string>(); foreach (var product in collection) { if (product.Id == null) { list.Add(null); } else { list.Add(product.Id.ToString()); } } return list.ToArray(); } However, it still fails with the same cast exception. I'm wondering if it has something to do with being in reflection? If so, is there anything that I can do here?? I'm open to architectural solutions, too!

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  • Hiding Group Column Names

    - by Robert
    You once replied to a post about hiding list group header names. http://edinkapic.blogspot.com/2008/06/hiding-list-view-group-headers.html I do not write code or jQuery at that. But you mentioned that it would be better to write a solution in jQuery. Would you have code that would hide the group header and colon in a 2003 list (SP v.2)? Do you have any good leads? Thanks. Robert S.

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  • How to avoid using the same identifier for Class Names and Property Names?

    - by Wololo
    Here are a few example of classes and properties sharing the same identifier: public Coordinates Coordinates { get; set; } public Country Country { get; set; } public Article Article { get; set; } public Color Color { get; set; } public Address Address { get; set; } This problem occurs more frequently when using POCO with the Entity Framework as the Entity Framework uses the Property Name for the Relationships. So what to do? Use non-standard class names? public ClsCoordinates Coordinates { get; set; } public ClsCountry Country { get; set; } public ClsArticle Article { get; set; } public ClsColor Color { get; set; } public ClsAddress Address { get; set; } public ClsCategory Category { get; set; } Yuk Or use more descriptive Property Names? public Coordinates GeographicCoordinates { get; set; } public Country GeographicCountry { get; set; } public Article WebArticle { get; set; } public Color BackgroundColor { get; set; } public Address HomeAddress { get; set; } public Category ProductCategory { get; set; } Less than ideal, but can live with it I suppose. Or JUST LIVE WITH IT? What are you best practices?

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  • Hashtable is that fast

    - by Costa
    Hi s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]. Is the hash function of the java string, I assume the rest of languages is similar or close to this implementation. If we have hash-Table and a list of 50 elements. each element is 7 chars ABCDEF1, ABCDEF2, ABCDEF3..... ABCDEFn If each bucket of hashtable contains 5 strings (I think this function will make it one string per bucket, but let us assume it is 5). If we call col.Contains("ABCDEFn"); // will do 6 comparisons and discover the difference on the 7th. The hash-table will take around 70 operations (multiplication and additions) to get the hashcode and to compare with 5 strings in bucket. and BANG it found. For list it will take around 300 comparisons to find it. for the case that there is only 10 elements, the list will take around 70 operations but the Hashtable will take around 50 operations. and note that hashtable operations are more time consuming (it is multiplications). I conclude that HybirdDictionary in .Net probably is the best choice for that most cases that require Hashtable with unknown size, because it will let me use a list till the list becomes more than 10 elements. still need something like HashSet rather than a Dictionary of keys and values, I wonder why there is no HybirdSet!! So what do u think? Thanks

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  • Strategies for when to use properties and when to use internal variables on internal classes?

    - by Edward Tanguay
    In almost all of my classes, I have a mixture of properties and internal class variables. I have always chosen one or the other by the rule "property if you need it externally, class variable if not". But there are many other issues which make me rethink this often, e.g.: at some point I want to use an internal variable from outside the class, so I have to refactor it into a property which makes me wonder why I don't just make all my internal variables properties in case I have to access them externally anyway, since most classes are internal classes anyway it aren't exposed on an API so it doesn't really matter if the internal variables are accessible from outside the class or not but then since C# doesn't allow you to instantiate e.g. List<string> property in the definition, then these properties have to be initialized in every possible constructor, so these variables I would rather have internal variables just to keep things cleaner in that they are all initialized in one place C# code reads more cleanly if constructor/method parameters are camel case and you assign them to pascal case properties instead of the ambiguity of seeing "templateIdCode" and having to look around to see if it is a local variable, method parameter or internal class variable, e.g. it is easier when you see "TemplateIdCode = templateIdCode" that this is a parameter being assigned to a class property. This would be an argument for always using only properties on internal classes. e.g.: public class TextFile { private string templateIdCode; private string absoluteTemplatePathAndFileName; private string absoluteOutputDirectory; private List<string> listItems = new List<string>(); public string Content { get; set; } public List<string> ReportItems { get; set; } public TextFile(string templateIdCode) { this.templateIdCode = templateIdCode; ReportItems = new List<string>(); Initialize(); } ... When creating internal (non-API) classes, what are your strategies in deciding if you should create an internal class variable or a property?

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  • Multi-threaded Pooled Allocators

    - by Darren Engwirda
    I'm having some issues using pooled memory allocators for std::list objects in a multi-threaded application. The part of the code I'm concerned with runs each thread function in isolation (i.e. there is no communication or synchronization between threads) and therefore I'd like to setup separate memory pools for each thread, where each pool is not thread-safe (and hence fast). I've tried using a shared thread-safe singleton memory pool and found the performance to be poor, as expected. This is a heavily simplified version of the type of thing I'm trying to do. A lot has been included in a pseudo-code kind of way, sorry if it's confusing. /* The thread functor - one instance of MAKE_QUADTREE created for each thread */ class make_quadtree { private: /* A non-thread-safe memory pool for int linked list items, let's say that it's * something along the lines of BOOST::OBJECT_POOL */ pooled_allocator<int> item_pool; /* The problem! - a local class that would be constructed within each std::list as the * allocator but really just delegates to ITEM_POOL */ class local_alloc { public : //!! I understand that I can't access ITEM_POOL from within a nested class like //!! this, that's really my question - can I get something along these lines to //!! work?? pointer allocate (size_t n) { return ( item_pool.allocate(n) ); } }; public : make_quadtree (): item_pool() // only construct 1 instance of ITEM_POOL per // MAKE_QUADTREE object { /* The kind of data structures - vectors of linked lists * The idea is that all of the linked lists should share a local pooled allocator */ std::vector<std::list<int, local_alloc>> lists; /* The actual operations - too complicated to show, but in general: * * - The vector LISTS is grown as a quadtree is built, it's size is the number of * quadtree "boxes" * * - Each element of LISTS (each linked list) represents the ID's of items * contained within each quadtree box (say they're xy points), as the quadtree * is grown a lot of ID pop/push-ing between lists occurs, hence the memory pool * is important for performance */ } }; So really my problem is that I'd like to have one memory pool instance per thread functor instance, but within each thread functor share the pool between multiple std::list objects.

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  • effective functional sort

    - by sreservoir
    I'm programming a function for a TI-NSpire, so I can't use the builtins from inside a function. What is the most generally efficient algorithm for sorting a list of numbers without modifying the list itself? (recursion and list-splitting are fair game, as is general use of math.)

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  • Jquery Find an XML element based on the value of one of it's children

    - by NateD
    I'm working on a simple XML phonebook app to learn JQuery, and I can't figure out how to do something like this: When the user enters the first name of a contact in a textbox I want to find the entire record of that person. The XML looks like this: <phonebook> <person> <number> 555-5555</number> <first_name>Evelyn</first_name> <last_name>Remington</last_name> <address>Edge of the Abyss</address> <image>path/to/image</image> </person> <person> <number>+34 1 6444 333 2223230</number> <first_name>Max</first_name> <last_name>Muscle</last_name> <address>Mining Belt</address> <image>path/to/image</image> </person> </phonebook> and the best I've been able to do with the jQuery is something like this: var myXML; function searchXML(){ $.ajax({ type:"GET", url: "phonebook.xml", dataType: "xml", success: function(xml){myXML = $("xml").find("#firstNameBox").val())} }); } What I want it to do is return the entire <person> element so I can iterate through and display all that person's information. Any help would be appreciated.

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  • Populate a tree from Hierarchical data using 1 LINQ statement

    - by Midhat
    Hi. I have set up this programming exercise. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication2 { class DataObject { public int ID { get; set; } public int ParentID { get; set; } public string Data { get; set; } public DataObject(int id, int pid, string data) { this.ID = id; this.ParentID = pid; this.Data = data; } } class TreeNode { public DataObject Data {get;set;} public List<DataObject> Children { get; set; } } class Program { static void Main(string[] args) { List<DataObject> data = new List<DataObject>(); data.Add(new DataObject(1, 0, "Item 1")); data.Add(new DataObject(2, 0, "Item 2")); data.Add(new DataObject(21, 2, "Item 2.1")); data.Add(new DataObject(22, 2, "Item 2.2")); data.Add(new DataObject(221, 22, "Item 2.2.1")); data.Add(new DataObject(3, 0, "Item 3")); } } } The desired output is a List of 3 treenodes, having items 1, 2 and 3. Item 2 will have a list of 2 dataobjects as its children member and so on. I have been trying to populate this tree (or rather a forest) using just 1 SLOC using LINQ. A simple group by gives me the desired data but the challenge is to organize it in TreeNode objects. Can someone give a hint or an impossibility result for this?

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