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  • Is there a best practice for maintaining history in a database?

    - by Pete
    I don't do database work that often so this is totally unfamiliar territory for me. I have a table with a bunch of records that users can update. However, I now want to keep a history of their changes just in case they want to rollback. Rollback in this case is not the db rollback but more like revert changes two weeks later when they realized that they made a mistake. The distinction being that I can't have a transaction do the job. Is the current practice to use a separate table, or just a flag in the current table? It's a small database, 5 tables each with < 6 columns, < 1000 rows total.

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  • A cross-platform application WPF, ASP.NET, Silverlight, WP7, XAML

    - by J. Lennon
    Considering the fact that all applications will interact with the web project (which will use the cloud or web services).. Is there any way to share my class models between applications? If yes, what is the best way to do it? About sending / receiving data from the Webservice, serialize and deserialize, how can I do this in a simple way without having to manually populate the objects? Any information about this applications would be really helpful!

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  • suggestions on syntax to express mathematical formula concisely

    - by aaa
    hello. I am developing functional domain specific embedded language within C++ to translate formulas into working code as concisely and accurately as possible. I post prototype in the comment, it is about 2 hundred lines long. Right now my language looks something like this (well, actually is going to look like): // implies two nested loops j=0:N, i=0,j (range(i) < j < N)[T(i,j) = (T(i,j) - T(j,i))/e(i+j)]; // implies summation over above expression sum(range(i) < j < N))[(T(i,j) - T(j,i))/e(i+j)]; I am looking for possible syntax improvements/extensions or just different ideas about expressing mathematical formulas as clearly and precisely as possible (in any language, not just C++). Can you give me some syntax examples relating to my question which can be accomplished in your language of choice which consider useful. In particular, if you have some ideas about how to translate the above code segments, I would be happy to hear them. Thank you just to clarify and give actual formula, my short-term goal is to express the following expression concisely where values in <> are already computed as 4-dimensional array

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  • C# Class Factories

    - by Andy
    I have a class called Foo that has a function that looks like the following List<Bar> LoadData(); Both Foo and Bar are in a library that I want to reuse in other projects. Now I am working on a new project and I want to subclass Bar. Let's call it NewBar. What is a simple and flexible way to get Foo.LoadData to return a list of NewBar? I think that a factory is needed or perhaps just a delegate function. Can anyone provide an example? Thanks, Andy

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  • Entering large amounts of text data in HTML form

    - by MakkyNZ
    Hi I have a web page that has a requirement to allow users to paste large amounts of text data from an Excel spreadsheet directly into the input controls of the page. Typically the user would be pasting anywhere between 150 to 300 spreadsheet cells that are all in one column. What are some good ways i could use to capture this data on the web page? thanks

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  • Which entities should be Aggregate Roots?

    - by MylesRip
    If Book aggregates Chapter which in turn aggregates Page, then what should be the aggregate root? One possibility might be: Book is an aggregate root with Chapter as a leaf and Chapter is an aggregate with Page as a leaf. In this scenario, Chapter is a leaf in one aggregate and a root in another. Is this okay? Would it make sense in this scenario to have two repositories, one for Book and another for Chapter? If so, then couldn't the Chapter repository be used to circumvent the fact that access to Chapter should only happen via Book? What would be the best way to handle a situation like this?

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  • PHP Store User Data without Sessions

    - by Sev
    Is there anyway to store users data such as userid, email, etc to be accessible from all pages of a website after they have logged in, but without using sessions or cookies? For example: class User { var $userid; var $username; var $email; .. methods.. } after they login at login.php $currentUser = new User($_POST['username']) now, how do I access $currentUser from another page, such as index.php if I shouldn't use sessions or cookies at all? so that I could do the following in index.php: if ($currentUser->userid > -1) { echo "you are logged in as: " . $currentUser->username; } else { echo "click here to login"; } i asked a similar question before, here, but the answers didn't fulfill my needs.

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  • Client-side user custom CSS single file for overriding multiple domains

    - by Cawas
    This is for using in Safari, though it could probably be used on Firefox as well. In Chrome you have to add a plugin anyway (which generally allow for custom CSS per domain), and Opera already allows this to be done without needing any CSS. But while it's for customizing on the client-side, it's also a pure CSS question. So I'm using no plugins here. So, again, I got a custom CSS code (easily) working for all domains. Now I want to get specify CSS code for each domain. All with just 1 CSS file that's being loaded by Safari. Over the web and googling, I've found two ways to supposedly do this, but none actually worked. They're both documented on userstyles.com: @-moz-document domain("your-domain.com") { }. This would be perfect, since I can have several tags like that and just choose which style will be loaded for which domain. It just doesn't work. @namespace is quite confusing and I've tried every variation I could think of. None worked.

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  • calling database driver in java app [basically a swing app]

    - by user993250
    I have made a java application that allows a user to choose from certain standards and then allows him to customize those standards according to his needs. Now, the customization [via a swing application] that has been made needs to be persistent. For this we use a database [mysql/access] and hook it to the application so that with each customization made, a table [if non-existent] is created [thus making it runtime and we can not pre-determine the table names or the keys of table etc] and an appropriate entry in the table is made. I have written the driver for this connection. How do I call it in the java application and what approach should I take? I would much appreciate that if somebody can refer me some example that not only shows a sample connection being made via driver but its appropriate calls to the database as well so that i can use it as a guide.

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  • What is the best way to expose a callback API - C++

    - by rursw1
    Hi, I have a C++ library that should expose some system\ resource calls as callbacks from the linked application. For example: the interfacing application (which uses this library) can send socket management callback functions - send, receive, open, close etc., and the library will use this implementation in stead of the library's implementation. (This way enables the application to manage the sockets by itself, can be useful). This library has to expose also more callbacks, like, for example, a password validation, so I wonder if there is a preferred method to expose the callback sending option in one API. Something like: int AddCallbackFunc (int functionCallbackType, <generic function prototype>, <generic way to pass some additional arguments>) Then within my library I will assign the callback to the appropriate function pointer according to the functionCallbackType parameter. Is there any way to implement it in a generic way which will fit ANY function prototype and ANY additional arguments? Your help will be more than appreciated... Thanks!

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  • When/Why to use Cascading in SQL Server?

    - by Joel Coehoorn
    When setting up foreign keys in SQL Server, under what circumstances should you have it cascade on delete or update, and what is the reasoning behind it? This probably applies to other databases as well. I'm looking most of all for concrete examples of each scenario, preferably from someone who has used them successfully.

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  • Can I set ignore_dup_key on for a primary key?

    - by Mr. Flibble
    I have a two-column primary key on a table. I have attempted to alter it to set the ignore_dup_key to on with this command: ALTER INDEX PK_mypk on MyTable SET (IGNORE_DUP_KEY = ON); But I get this error: Cannot use index option ignore_dup_key to alter index 'PK_mypk' as it enforces a primary or unique constraint. How else should I set IGNORE_DUP_KEY to on?

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  • Ignoring (serious) errors to keep the program alive?

    - by SQuirreL bites
    One of the main things I wanted to achieve in my experimental programming language was: When errors occur (Syntax, Name, Type, etc.) keep the program running, no matter how serious or devastating it is. I know that this is probably very bad, but I just wanted something that doesn't kill itself on every error - I find it interesting what happens when a serious error occurs but the program continues. Does this "paradigm" have a name? I mean expect for How bad is it to do the above? Are there programs in use out there that just follow: "Hey, this is a fatal, unexpected error - but you know what? I don't care!"?

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  • O(log n) algorithm for merging lists and computing rank?

    - by Eternal Learner
    Given two sorted lists, each containing n real numbers, is there a O(log?n) time algorithm to compute the element of rank i (where i coresponds to index in increasing order) in the union of the two lists, assuming the elements of the two lists are distinct? I can think of using a Merge procedure to merge the 2 lists and then find the A[i] element in constant time. But the Merge would take O(n) time. How do we solve it in O(log n) time?

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  • Detect session hang and kill it

    - by Jack Juiceson
    Hi all, I have an asp.net page that runs certain algorithm and returns it's output. I was wondering what will happen and how to handle a case where the algorithm due to a bug goes into infinite loop. It will hog the cpu and other sessions will be served very slowly. I would love to have a way to tell IIS, if processing Algo.aspx takes more than 5 seconds, kill it or something like that. Thanks in advance

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  • Is it okay to rely on javascript for menu layout?

    - by Ryan
    I have a website template where I do not know the number of menu items or the size of the menu items that will be required. The js below works exactly the way I want it to, however this is the most js I've every written. Are there any disadvantages or potential problems with this method that I'm not aware of because I'm a js beginner? I'm currently manually setting the padding for each site. Thank you! var width_of_text = 0; var number_of_li = 0; // measure the width of each <li> and add it to the total with, increment li counter $('li').each(function() { width_of_text += $(this).width(); number_of_li++; }); // calculate the space between <li>'s so the space is equal var padding = Math.floor((900 - width_of_text)/(number_of_li - 1)); // add the padding the all but the first <li> $('li').each(function(index) { if (index !== 0) { $(this).css("padding-left", padding); } });

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  • What to do when using Contract.Assert(true) and the method must return something?

    - by devoured elysium
    I have a bit of code with the following logic: //pseudo-code foreach (element in elementList) { if (element is whatever) return element; } } In theory, there is always one element that is whatever, so this method should pose no problems. In any case, I've put an assertion on the end of the method just to be sure: //pseudo-code foreach (element in elementList) { if (element is whatever) return element; } } Contract.Assert(true, "Invalid state!"); The problem is that as this method has to return something, and the compiler doesn't understand that the assertion will break the program execution. Before using Contracts, in these kind of situations, I used to throw an Exception, which solved the problem. How would you handle this with Contract.Assert()? Returning null or default(element_type) after the Contract.Assert() call knowing it will never be called and shutting up the compiler? Or is there any other more elegant way of doing this? Thanks

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  • Many tables for many users?

    - by Seagull
    I am new to web programming, so excuse the ignorance... ;-) I have a web application that in many ways can be considered to be a multi-tenant environment. By this I mean that each user of the application gets their own 'custom' environment, with absolutely no interaction between those users. So far I have built the web application as a 'single user' environment. In other words, I haven't actually done anything to support multi-users, but only worked on the functionality I want from the app. Here is my problem... What's the best way to build a multi-user environment: All users point to the same 'core' backend. In other words, I build the logic to separate users via appropriate SQL queries (eg. select * from table where user='123' and attribute='456'). Each user points to a unique tablespace, which is built separately as they join the system. In this case I would simply generate ALL the relevant SQL tables per user, with some sort of suffix for the user. (eg. now a query would look like 'select * from table_ where attribute ='456'). In short, it's a difference between "select * from table where USER=" and "select * from table_USER".

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  • Object Events, how do are they implemented

    - by Malfist
    Events are really awesome, and I wouldn't know what I would do without them, but they're a mystery to me. I'm talking about events in a sense, a function(s) is called if a property, or value, a special event happens. I have only the vaguest idea how these actually work. I know it's an observer pattern, but I don't truly know how it works and/or how to implement it. Can someone explain that to me?

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  • A better name for INeedSomething... ?

    - by Daniel Severin
    I was trying pick a name for an interface through which I can pass something into an object like: If the object is INeedX then SetX(some x) method will be called; If the object is INeedY then SetY(some y) method will be called; and so on. (funny as hell, I know :) ) I try to find a different name for this kind of interfaces but I can't figure this out. Does anybody have an idea how to name the INeedSomething interface ?

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  • Best way to have common class shared by both C++ and Ruby?

    - by shuttle87
    I am currently working on a project where a team of us are designing a game, all of us are proficient in ruby and some (but not all) of us are proficient in c++. Initially we made the backend in ruby but we ported it to c++ for more speed. The c++ port of the backend has exactly the same features and algorithms as the original ruby code. However we still have a bunch of code in ruby that does useful things but we want it to now get the data from the c++ classes. Our first thought was that we could save some of the data structures in something like XML or redis and call that, but some of the developers don't like that idea. We don't need anything particularly complex data structures to be passed between the different parts of the code, just tuples, strings and ints. Is there any way of integrating the ruby code so that it can call the c++ stuff natively? Will we need to embed code? Will we have to make a ruby extension? If so are there any good resources/tutorials you could suggest? For example say we have this code in the c++ backend: class The_game{ private: bool printinfo; //print the player diagnostic info at the beginning if true int numplayers; std::vector<Player*> players; string current_action; int action_is_on; // the index of the player in the players array that the action is now on //more code here public: Table(std::vector<Player *> in_players, std::vector<Statistics *> player_stats ,const int in_numplayers); ~Table(); void play_game(); History actions_history; }; class History{ private: int action_sequence_number; std::vector<Action*> hand_actions; public: void print_history(); void add_action(Action* the_action_to_be_added); int get_action_sequence_number(){ return action_sequence_number;} bool history_actions_are_equal(); int last_action_size(int street,int number_of_actions_ago); History(); ~History(); }; Is there any way to natively call something in the actions_history via The_game object in ruby? (The objects in the original ruby code all had the same names and functionality) By this I mean: class MyRubyClass def method1(arg1) puts arg1 self.f() # ... but still available puts cpp_method.the_current_game.actions_history.get_action_sequence_number() end # Constructor: def initialize(arg) puts "In constructor with arg #{arg}" #get the c++ object here and call it cpp_method end end Is this possible? Any advice or suggestions are appreciated.

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