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  • Can I improve performance by refactoring SQL commands into classes?

    - by Matthew Jones
    Currently, my entire website does updating from SQL parameterized queries. It works, we've had no problems with it, but it can occasionally be very slow. I was wondering if it makes sense to refactor some of these SQL commands into classes so that we would not have to hit the database so often. I understand hitting the database is generally the slowest part of any web application For example, say we have a class structure like this: Project (comprised of) Tasks (comprised of) Assignments Where Project, Task, and Assignment are classes. At certain points in the site you are only working on one project at a time, and so creating a Project class and passing it among pages (using Session, Profile, something else) might make sense. I imagine this class would have a Save() method to save value changes. Does it make sense to invest the time into doing this? Under what conditions might it be worth it?

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  • C++, create an instance from a static method

    - by Manux
    Hello, let's say I want my users to use only one class, say SpecialData. Now, this data class would have many methods, and depending on the type of data, the methods do different things, internally, but return externally similar results. Therefore my wanting to have one "public" class and other "private", child classes that would change the behavior of methods, etc... It would be amazingly more simple for some types of data that need to be built to do something like this: SpecialData& sm = SpecialData::new_supermatrix(); and new_supermatrix() would return a SuperMatrix instance, which inherits from most behaviors of SpecialData. my header: static SpecialData& new_supermatrix(); my cpp: SpecialData& SpecialData::new_supermatrix()(){ return SuperMatrix(MATRIX_DEFAULT_MAGNITUDE,1000,1239,FLOAT32,etc...); } The problem is, I get this error, which is probably logical due to the circumstances: invalid initialization of non-const reference of type ‘SpecialData&’ from a temporary of type ‘SpecialData’ So, any ideas?

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  • Use SQL query to populate property in nHibernate mapping file

    - by brainimus
    I have an object which contains a property that is the result of an SQL statement. How do I add the SQL statement to my nHibernate mapping file? Example Object: public class Library{ public int BookCount { get; set; } } Example Mapping File: <hibernate-mapping> <class name="Library" table="Libraries"> <property name="BookCount" type="int"> <- This is where I want the SQL query to populate the value. -> </class> </hibernate-mapping> Example SQL Query: SELECT COUNT(*) FROM BOOKS WHERE BOOKS.LIBRARY_ID = LIBRARIES.ID

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  • Can I improve performance by refactoring SQL commands into C# classes?

    - by Matthew Jones
    Currently, my entire website does updating from SQL parameterized queries. It works, we've had no problems with it, but it can occasionally be very slow. I was wondering if it makes sense to refactor some of these SQL commands into classes so that we would not have to hit the database so often. I understand hitting the database is generally the slowest part of any web application For example, say we have a class structure like this: Project (comprised of) Tasks (comprised of) Assignments Where Project, Task, and Assignment are classes. At certain points in the site you are only working on one project at a time, and so creating a Project class and passing it among pages (using Session, Profile, something else) might make sense. I imagine this class would have a Save() method to save value changes. Does it make sense to invest the time into doing this? Under what conditions might it be worth it?

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  • PHP Object Oriented Web Application

    - by Sev
    I have a class called "Layout" for the layout of the page, another class called "User" for the user. Every page I create, I instantiate a new Layout. When a user logs in, there is a new User instantiated. How do I get an instance of the layout class to know about the instantiated user? I could also save the entire instance of the User in a session variable. I assume that's a bad idea though. What are the best practices for this?

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  • mysql conditional query - complicated!

    - by emre
    i want to get distinct values for a field, let say: field1... ok this needs a query like: "select distint(field1) from table" however for some records, field1 is empty and there is another column that is an alternative to field1, which is field2. now; for the records where field1 is empty i need to use the value of field2. i think i need sort of a conditional select statement with if control something like: "select distinct( (if(field1!='') field1 else field2) ) from table" but i have no idea on how to write it. any help is appricated...

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  • Java Enum Newbie Question

    - by ikurtz
    i have a situation where i need the Checker enum below used in multiple classes: package Sartre.Connect4; public enum Checker { EMPTY, RED, YELLOW } so i put the Checker in a Checker.java file and then from the classes that need it i simply do the following: example: public Cell(){ currentCell = Checker.EMPTY; } example: public Cell(Checker checker){ currentCell = checker; } and the code compiles fine and runs fine also. so what is my question? well being new to Java i am just wondering if the way i use Checker without encapsulating it in a class is a sound implementation? it may be because of The enum declaration defines a class (called an enum type). as noted in Java docs enum tutorial page. thank you for your insight into this matter.

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  • Question about C# properties

    - by Impz0r
    Hey there, i bumped the other day into a little problem regarding C#'s properties. Let's say i do have this setup: public class Point { public float X; public float Y; } public class Control { protected Point m_Position = new Point(); public Position { get { return m_Position; } set { m_Position = value; } // reorganize internal structure.. reorganize(); } protected reorganize() { // do some stuff } } This is all fine, but when it comes to usage, i could write something like: Control myControl = new Control(); myControl.Position.X = 1.0f; The thing is, my Control class wont recognize that the Position has been changed because set hasn't been called. So i guess my question is, is there a way to make Control aware of any Position changes? Thanks in advance! Mfg Imp

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  • Optional parameters for interfaces

    - by bryanjonker
    Using c# 4.0 -- building an interface and a class that implements the interface. I want to declare an optional parameter in the interface and have it be reflected in the class. So, I have the following: public interface IFoo { void Bar(int i, int j=0); } public class Foo { void Bar(int i, int j=0) { // do stuff } } This compiles, but it doesn't look right. The interface needs to have the optional parameters, because otherwise it doesn't reflect correctly in the interface method signature. Should I skip the optional parameter and just use a nullable type? Or will this work as intended with no side effects or consequences?

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  • fopen in C(Linux) returns "Too many open files"

    - by liv2hak
    static char filename[128] = "trace.txt"; g_file = fopen(filename, "w"); if(NULL == g_file) { printf("Cannot open file %s.error %s\n",filename,strerror(errno)); exit(1); } I am trying to open a empty text file named trace.txt in write mode (in my working directory.) The program is creating an empty file trace.txt in my directory.but the check (NULL == g_file) is returning true and it is returning error code 24 (Too many open files.).Any idea why this is.This is the first file I am opening in my program.

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  • SQL returns non-array value in PHP

    - by DeadMG
    $request = 'SELECT * FROM flight WHERE Id = \''.$_SESSION['LFLightRadio'].'\''; $data = mysql_fetch_array(mysql_query($request, $SQL)); echo '<table class="table">'; foreach($data as $key => $value) { echo '<th class="head" align="center" height="19">'.$key.'</th>'; } echo '<tr>'; foreach($data as $key => $value) { echo '<td class="cell" align="center" height="19">'.$value.'</td>'; } echo '</tr></table>'; I know that the LFlightRadio value is set, and is a value returned by the Id value of a previously returned row from the flight database. So within "flight", a record definitely exists with this Id. But, this still gives me a non-array result, so that when I try to use foreach on it, it errors out. Suggestions?

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  • Convert long number as string in the serialization

    - by Bruno
    I have a custom made class that use a long as ID. However, when I call my action using ajax, my ID is truncated and it loses the last 2 numbers because javascript loses precision when dealing with large numbers. My solution would be to give a string to my javascript, but the ID have to stay as a long on the server side. Is there a way to serialize the property as a string? I'm looking for some kind of attribute. Controller public class CustomersController : ApiController { public IEnumerable<CustomerEntity> Get() { yield return new CustomerEntity() { ID = 1306270928525862486, Name = "Test" }; } } Model public class CustomerEntity { public long ID { get; set; } public string Name { get; set; } } JSON Result [{"Name":"Test","ID":1306270928525862400}]

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  • Reuse C++ Header files

    - by Amrish
    Guys, I have a Visual C++ solution with 2 projects AlgorithmA & AlgorithmB and both share a common header file RunAlgo.h with the class declaration. Each project in the solution has its own unique implementation for the header file. I am trying to compile a DLL out of the common header file RunAlgo.h and add reference to this DLL in the projects AlgorithmA & AlgorithmB. I have then included separate RunAlgo.cpp definition file in both my projects. The problem is that I am getting linker errors while compiling the new DLL project which has only the header file. So, the question is Can a header file with only class declaration be compiled into a DLL (Similar to class library containing an Interface in C#)? For the above scenario, is there a better approach to reuse the common Header file among projects? Should the above method work (re-check my code?)

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  • Best way to map/join two autogenerated enums

    - by tomlip
    What is the best C++ (not C++11) way of joining two enums from autogenerated class similar to one presented below: namespace A { namespace B { ... class CarInfo { enum State { // basically same enums defined in different classes Running, Stopped, Broken } } class BikeInfo { enum State { // basically same enums defined in different classes Running, Stopped, Broken } } } } What is needed is unified enum State for both classes that is seen to outside world alongside with safe type conversion. The best and probably most straightforward way I came up with is to create external enum: enum State { Running, Stopped, Broken } together with conversion functions State stateEnumConv(A::B::CarInfo::State aState); State stateEnumConv(A::B::BikeInfo::State aState); A::B::CarInfo::State stateEnumConv(State aState); A::B::BikeInfo::State stateEnumConv(State aState); Direction into right approach is needed. Gosh coming from C I hate those long namespaces everywhere an I wish it could be only A::B level like in presented example. Four conversion functions seem redundant note that CarInfo::State and BikeInfo::State has same enum "members".

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  • Template inheritance: X is not a template

    - by user2923917
    I am trying to build a inheritance-structure which looks like: Base - template Grandpa - template Father class Base {}; template <int x> class Grandpa: public Base {}; template <int x> class Father: public Grandpa<x> {}; However, the compiler complains when compiling Father, that Grandpa is not a template. I guess it is just some synthatic issue, however everything I've tried so far led to even more compiler complaints ;) Any idea whats wrong?

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  • When to trash hashmap contents to avoid performance degradation?

    - by Jack
    Hello, I'm woking on Java with a large (millions) hashmap that is actually built with a capacity of 10.000.000 and a load factor of .75 and it's used to cache some values since cached values become useless with time (not accessed anymore) but I can't remove useless ones while on the way I would like to entirely empty the cache when its performance starts to degrade. How can I decide when it's good to do it? For example, with 10 millions capacity and .75 should I empty it when it reaches 7.5 millions of elements? Because I tried various threshold values but I would like to have an analytic one. I've already tested the fact that emping it when it's quite full is a boost for perfomance (first 2-3 algorithm iterations after the wipe just fill it back, then it starts running faster than before the wipe) Thanks

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  • remove/restore elements, maintaining their events and element's children

    - by Emin
    I came to a situation where I need to edit the following in a way that, on some event (lets assume the 'click' event in this case) I need to remove (or unwrap?) the .container and the .header and have the .itemlist still visible/available on the page. And then, I need to restore .container and .header back again on some other event, while still maintain the event listeners on the a tags, and if possible, without removing the said items from the DOM. Is this possible? <ul class="container"> <li class="header"><a href="#">delete</a> | <a href="#">edit</a></li> <ul class="itemlist"> <li>some item</li> <li>some other item</li> </ul> </ul>

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  • Unmanaged C++ instantiation question

    - by Jim Jones
    Want to verify that my understanding of how this works. Have an unmanaged C++ Class with one public instance variable: char* character_encoding; and whose only constructor is defined as: TF_StringList(const char* encoding = "cp_1252"); when I use this class in either managed or unmanaged C++, the first thing I do is declare a pointer to an object of this class: const TF_StringList * categories; Then later I instantiate it: categories = new TF_StringList(); this gives me a pointer to an object of type TF_StringList whose variable character_encoding is set to "cp_1252"; So, is all that logic valid? Jim

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  • Remove C# attribute of a property dynamically

    - by SysAdmin
    Hi, I have a class with a set of properties As given below. class ContactInfo { [ReadOnly(true)] [Category("Contact Info")] public string Mobile { get; set; } [Category("Contact Info")] public string Name{ get; set; } } The objects of this class is being assigned to a property grid, so that the users can update an existing contact. you can see that Mobile is marked as ReadOnly. But, when I want to add an entirely new Contact, I would want the users to be able to edit the contact Mobile also. For that I need to remove the Readonly property dynamically from the Type, before assigning the object to the property grid. Is it possible?

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  • Code won't exit foreach block

    - by Matt
    I've got the following C# code segment that takes a list, finds objects that are ready to update, then shoves them into a temp list, deletes from the main list, and then goes on its merry way. My issue is that the foreach block, which cycles through my main list, won't exit. TempLog.Clear(); //Ensure TempLog is empty foreach (CLogger ready in PlayerLog) { if (ready.UpdateReady == true) // Record is ready to be updated in database { TempLog.Add(ready); // Add record to templog PlayerLog.Remove(ready); // Remove from playerlog } } <---- Never reaches this point if (TempLog.Count > 0) // Just check that templog isn't empty { new Thread(Update).Start(); // Run update code } I've put heaps of debugging in, and I can watch PlayerLog start at 1, TempLog at 0, then it enters the foreach loop, picks up that the record UpdateReady flag is on, TempLog goes to 1, PlayerLog goes to 0, then it just stops.. No errors, just stops.. Thanks for the help :)

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  • Understanding Nested If.. Else statements

    - by user1174762
    For some reason my PHP login script keeps returning "invalid email/password combination", yet i know I am entering the correct email and password. Does anyone see what I might be doing wrong? <?php $email= $_POST['email']; $password= $_POST['password']; if (!empty($email) && !empty($password)) { $connect= mysqli_connect("localhost", "root", "", "si") or die('error connecting with the database'); $query= "SELECT user_id, email, password FROM users WHERE email='$email' AND password='$password'"; $result= mysqli_query($connect, $query) or die('error with query'); if (mysqli_num_rows($result) == 1) { $row= mysqli_fetch_array($result); setcookie('user_id', $row['user_id']); echo "you are now logged in"; } else { echo "invalid username/password combination"; } } else { echo" you must fill out both username and password"; } ?>

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  • How to Add Horizontal line in Javascript

    - by user54197
    I would like to add a horizontal seperating line on a dynamic populated table. How do I do this? Below is a snippet. function addNewRow() { $('#displayTable tr:last').after('<tr><td style="font-size:smaller;" class="dataField1"></td><td style="font-size:smaller;" class="dataField2"></td><td style="font-size:smaller;" class="dataField3"></td></tr>'); var $tr = $('#displayTable tr:last'); $tr.find('.dataField1').text($('#txtName').val()); $tr.find('.dataField2').text($('#txtAddress').val()); $tr.find('.dataField3').text('document.write("<tr><td colspan=\"2\"><hr \/><\/td><\/tr>"); }

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  • Emulator batteryService not working

    - by user568551
    So i've got a 1.6 emulator running. I have a receiver with action power connected and disconnected filters. when i connect to the emulator through telnet and issue the power ac on or power ac off command, logcat shows: 01-11 21:33:01.096: ERROR/BatteryService(67): Could not open '/sys/class/power_supply/usb/online' 01-11 21:33:01.104: ERROR/BatteryService(67): Could not open '/sys/class/power_supply/battery/batt_vol' 01-11 21:33:01.104: ERROR/BatteryService(67): Could not open '/sys/class/power_supply/battery/batt_temp' and my receiver does not get activated. It was working just fine yesterday and now it does not. I tried reinstalling the AVD, and also deleted and reinstalled the SDK from the SDK manager. Works fine in my 2.2 emulator. Any ideas?

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  • [C++] std::string manipulation: whitespace, "newline escapes '\'" and comments #

    - by rubenvb
    Kind of looking for affirmation here. I have some hand-written code, which I'm not shy to say I'm proud of, which reads a file, removes leading whitespace, processes newline escapes '\' and removes comments starting with #. It also removes all empty lines (also whitespace-only ones). Any thoughts/recommendations? I could probably replace some std::cout's with std::runtime_errors... but that's not a priority here :) const int RecipeReader::readRecipe() { ifstream is_recipe(s_buffer.c_str()); if (!is_recipe) cout << "unable to open file" << endl; while (getline(is_recipe, s_buffer)) { // whitespace+comment removeLeadingWhitespace(s_buffer); processComment(s_buffer); // newline escapes + append all subsequent lines with '\' processNewlineEscapes(s_buffer, is_recipe); // store the real text line if (!s_buffer.empty()) v_s_recipe.push_back(s_buffer); s_buffer.clear(); } is_recipe.close(); return 0; } void RecipeReader::processNewlineEscapes(string &s_string, ifstream &is_stream) { string s_temp; size_t sz_index = s_string.find_first_of("\\"); while (sz_index <= s_string.length()) { if (getline(is_stream,s_temp)) { removeLeadingWhitespace(s_temp); processComment(s_temp); s_string = s_string.substr(0,sz_index-1) + " " + s_temp; } else cout << "Error: newline escape '\' found at EOF" << endl; sz_index = s_string.find_first_of("\\"); } } void RecipeReader::processComment(string &s_string) { size_t sz_index = s_string.find_first_of("#"); s_string = s_string.substr(0,sz_index); } void RecipeReader::removeLeadingWhitespace(string &s_string) { const size_t sz_length = s_string.size(); size_t sz_index = s_string.find_first_not_of(" \t"); if (sz_index <= sz_length) s_string = s_string.substr(sz_index); else if ((sz_index > sz_length) && (sz_length != 0)) // "empty" lines with only whitespace s_string.clear(); } Some extra info: the first s_buffer passed to the ifstream contains the filename, std::string s_buffer is a class data member, so is std::vector v_s_recipe. Any comment is welcome :)

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