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  • Singleton constructor question

    - by gillyb
    Hi, I created a Singleton class in c#, with a public property that I want to initialize when the Singleton is first called. This is the code I wrote : public class BL { private ISessionFactory _sessionFactory; public ISessionFactory SessionFactory { get { return _sessionFactory; } set { _sessionFactory = value; } } private BL() { SessionFactory = Dal.SessionFactory.CreateSessionFactory(); } private object thisLock = new object(); private BL _instance = null; public BL Instance { get { lock (thisLock) { if (_instance == null) { _instance = new BL(); } return _instance; } } } } As far as I know, when I address the Instance BL object in the BL class for the first time, it should load the constructor and that should initialize the SessionFactory object. But when I try : BL.Instance.SessionFactory.OpenSession(); I get a Null Reference Exception, and I see that SessionFactory is null... why?

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  • Python CLI tool - general parsing question

    - by WinkyWolly
    If possible I would like to use the following structure for a command however I can't seem to figure out how to achieve this in Python: ./somescript.py arg <optional argument> -- "some long argument" Would it be possible to achieve this in a feasible manner without too much dirty code? Or should I just reconsider the syntax (which is primarily preference). Thanks!

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  • Question about Architecture for Viewing Images in ASP.NET MVC App

    - by Charlie Flowers
    I have an approach in mind for an image viewer in a web app, and want to get a sanity check and any thoughts you stackoverflowers might have. Here's the whirlwind nutshell summary: I'm working on an ASP.NET MVC application that will run in my company's retail stores. Even though it is a web application, we own the store machines and have control over them. We have a "windows agent" running on the store machine which we can talk to from the browser via javascript (it is a WCF service, and our web app has permission to talk to it from the browser). One of the web pages needs to be an "image viewer" page with some common things like Rotate & Zoom. Now, there are some WebForms controls that offer Rotate and Zoom. However, they take up server resources and generate a good bit of traffic between the server and the browser. For example, the Rotate function would cause an ajax call to the server, which would then generate a new image written to a .NET Canvas object, which would then be written to a file on the server, which would then be returned from the ajax call and refreshed inside the browser. Normally, that's a pretty good way of doing things. But in our case, we have code running on the store machine that we can communicate with. This leads me to consider the following approach: When the user asks to view an image, we tell our "windows agent" to download it from our image server to the store machine. We then redirect our browser to our image viewer page, which will pull the image from the local file we just wrote to the store machine. When the user clicks "Rotate", we cause JavaScript code in the browser to call our "windows agent" software, asking it to perform the "Rotate" function. The "windows agent" does the rotation using the same kind of imaging control that would formerly have been used on the server, but it does so now on the store machine. Javascript in the browser then refreshes the image on the page to show the newly rotated image. Zoom and similar features would be implemented the same way. This seems to be much more efficient, scalable, and responsive for the end-users. However, I've never heard of anything like it being done, mostly because it's rare to have this combination of a web app plus a "windows agent" on the client machine. What do you think? Feasible? Reasonable? Any pitfalls I overlooked or improvements / suggestions you can see? Has anyone done anything like this who would like to offer the wisdom of experience? Thanks!

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  • basic question with a dtd

    - by voodoomsr
    i need an element with the characteristics <!ELEMENT section ((comment*)|definition|(comment*))> but that is ambiguous, i get the next message in visual studio Multiple definition of element 'comment' causes the content model to become ambiguous. A content model must be formed such that during validation of an element information item sequence, the particle contained directly, indirectly or implicitly therein with which to attempt to validate each item in the sequence in turn can be uniquely determined without examining the content or attributes of that item, and without any information about the items in the remainder of the sequence. So how can i write correctly that? the correct structure is one definition surrounded by possibles comments elements.

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  • rotating circle with swipe question

    - by Joe
    Okay so I'm making something that basically works as a knob, but only half on the screen -- so I just need horizontal swipes to cause it to rotate. I have it nearly all sorted with one exception: if you change direction of your swipe in mid-swipe, the rotation doesn't change direction. I even can see the problem, but not sure what to do about a solution. So in my touchesMoved, I get the swipe into radians in the predictable way: CGFloat radians = atan2f(location.y - centerY, location.x - centerX); I then store radians, add/subtract it to previous rotation and then give the result to the CATransform3D. So the prob is that even though the swipe changes direction, there is a "balance" which doesn't allow an immediate change of direction. Does this make any sense?

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  • MUD (game) design concept question about timed events.

    - by mudder
    I'm trying my hand at building a MUD (multiplayer interactive-fiction game) I'm in the design/conceptualizing phase and I've run into a problem that I can't come up with a solution for. I'm hoping some more experienced programmers will have some advice. Here's the problem as best I can explain it. When the player decides to perform an action he sends a command to the server. the server then processes the command, determines whether or not the action can be performed, and either does it or responds with a reason as to why it could not be done. One reason that an action might fail is that the player is busy doing something else. For instance, if a player is mid-fight and has just swung a massive broadsword, it might take 3 seconds before he can repeat this action. If the player attempts to swing again to soon, the game will respond indicating that he must wait x seconds before doing that. Now, this I can probably design without much trouble. The problem I'm having is how I can replicate this behavior from AI creatures. All of the events that are being performed by the server ON ITS OWN, aka not as an immediate reaction to something a player has done, will have to be time sensitive. Some evil monster has cast a spell on you but must wait 30 seconds before doing it again... I think I'll probably be adding all these events to some kind of event queue, but how can I make that event queue time sensitive?

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  • design question for transportation agency/workflow system

    - by George2
    Hello everyone, I am designing a transportation agency/workflow system, and it including 3 types of people, customer who requests to transport some stuff, drivers who deliver the stuff, and truck manager who manages transport source/destination truck coordination and communicates/organizes drivers. The system is expected to be a web site, and 3 kinds of people could use the web site to submit request, accept request, monitor status of specific stuff transportation, etc. The web site is more like an open agency or a workflow system. I am wondering whether there are any existing technologies, tools or projects (better to be open source, but not a must) which I could build my application faster based on? I prefer to use .Net technologies, but not a must. thanks in advance, George

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  • PreparedStatement question in Java against Oracle.

    - by fardon57
    Hi everyone, I'm working on the modification of some code to use preparedStatement instead of normal Statement, for security and performance reason. Our application is currently storing information into an embedded derby database, but we are going to move soon to Oracle. I've found two things that I need your help guys about Oracle and Prepared Statement : 1- I've found this document saying that Oracle doesn't handle bind parameters into IN clauses, so we cannot supply a query like : Select pokemon from pokemonTable where capacity in (?,?,?,?) Is that true ? Is there any workaround ? ... Why ? 2- We have some fields which are of type TIMESTAMP. So with our actual Statement, the query looks like this : Select raichu from pokemonTable where evolution = TO_TIMESTAMP('2500-12-31 00:00:00.000', 'YYYY-MM-DD HH24:MI:SS.FF') What should be done for a prepared Statement ? Should I put into the array of parameters : 2500-12-31 or TO_TIMESTAMP('2500-12-31 00:00:00.000', 'YYYY-MM-DD HH24:MI:SS.FF') ? Thanks for your help, I hope my questions are clear ! Regards,

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  • iPhone/Objective-C struct question my own CGRectZero

    - by Mark
    I am designing a Padding struct as follows: /* Padding. */ struct CGPadding { CGFloat left; CGFloat top; CGFloat right; CGFloat bottom; }; typedef struct CGPadding CGPadding; CG_INLINE CGPadding CGPaddingMake(CGFloat left, CGFloat top, CGFloat right, CGFloat bottom) { CGPadding p; p.left = left; p.top = top; p.right = right; p.bottom = bottom; return p; } This all works perfectly well, the problem is how can I create a const CGPadding CGPaddingZero? If I do like this: const CGPadding CGPaddingZero = (CGPadding){0.0, 0.0, 0.0, 0.0}; It doesnt work. So what am I doing wrong?

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  • visual studio 2002: c# threading question

    - by dotnet-practitioner
    Hi, I have a piece of code where I send a file content over tcp/ip channel. There are times when this connection hangs causing entire application to freeze. Is there a way for my main thread to spawn a worker thread and monitor that worker thread. If worker thread succeeds, well and good. If it hangs , the main thread could log error message and continue. How can I simulate in my test code that a worker thread is hanging. please let me know what could the code look like. I am using C# Visual studio 2002.

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  • XNA Vector2 Rotation Question

    - by Tom Allen
    I'm messing about with some stuff in XNA and am trying to move an object around asteroids-style in that you press left and right to rotate and up/down to go forwards and backwards in the direction you are pointing. I've got the rotation of the sprite done, but i can't get the object to move in the direction you've pointed it, it always moves up and down on the x = 0 axis. I'm guessing this is straight forward but I just can't figure it out. My "ship" class has the following properties which are note worthy here: Vector2 Position float Rotation The "ship" class has an update method is where the input is handled and so far I've got the following: public void Update(GameTime gameTime) { KeyboardState keyboard = Keyboard.GetState(); GamePadState gamePad = GamePad.GetState(PlayerIndex.One); float x = Position.X; float y = Position.Y; if (keyboard.IsKeyDown(Keys.Left)) Rotation -= 0.1f; if (keyboard.IsKeyDown(Keys.Right)) Rotation += 0.1f; if (keyboard.IsKeyDown(Keys.Up)) y -= ??; if (keyboard.IsKeyDown(Keys.Down)) y += ??; this.Position = new Vector2(x, y); } Any help would be most appreciated!

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  • Question about select UITableViewCell fields

    - by Joaquin McCoy
    Hi guys, I've a custom UITableViewCell like this: +--------------------------+ | username | | | | --- <image> -- | | | | <like it> | +--------------------------+ It display an username, an image and a button "Like it" to like image. I don't want that the entire cell is selectable, I want a user can tap on "username" to see a new view that show username information. The same for image, when user tap on image, he could see the image in a new view. Now I can only select my entire cell. How can I implement something like this? Thanks. When you click on the username you'll see a view for user information. The entire cell is not selectable.

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  • DMX Analysis Services question

    - by user282382
    Hi, I am have two mining models, both are time series. One is [Company_Inputs] and the other is [Booking_Projections]. What I want to do is use EXTEND_MODEL_CASES to join the results of [Company_Inputs] as the extended cases. So basically something like: Select Flattened PredictTimeSeries([Bookings], 1, 6, EXTEND_MODEL_CASES) FROM [Booking_Projections] Natural Prediction Join (Select Flattened PredictTimeSeries([Metric1], 1, 6) From [Company_Inputs]) AS T This code of course doesn't work, but the idea is to use the predictions made from [Company_Inputs] as cases for predicting future values of [Booking_Projections] If anyone has an idea of how I can accomplish this I would appreciate it very much.

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  • Simple WCF question.

    - by bearrito
    So I am learning WCF and I have run across an issue that I believe has to do with Instance Control/State but I am not sure. Workflow is as follows, Basic client/server paradigm. The client calls a Method RetrieveBusinessObjects(criteria) and the server calls the datalayer and then puts them in an IList on the server side. It does not return this list to the calling Client. The client would then call a method say DisplayBusinessObjects() which would retrieve the IList from the Server, serialize them, bring them across the wire and display them. If i try this using the WCFTestClient it works. If I run it from an actual client then I get back an BusinessObject[] of size 0. Which to me indicates I had no objects to return. Is that a state mgmt issue or am I missing something?

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  • Expose subset of a class - design question

    - by thanikkal
    Suppose i have a product class with about close to 100 properties. Now for some operations (Say tax calculation) i dont really need this bulky product type, rather only a subset that has price related properties. I am not sure if i should create different snap shots(class) of products that just has the properties that i am interested in. what would be the ideal approach so that i don't unnecessarily pass around unsought fluff? Thanks in advance.

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  • Mysql regexp performance question

    - by Tim
    Rumour has it that this; SELECT * FROM lineage_string where lineage like '%179%' and lineage regexp '(^|/)179(/|$)' Would be faster than this; SELECT * FROM lineage_string where lineage regexp '(^|/)179(/|$)' Can anyone confirm ? Or know a decent way to test the speed of such queries. Thanks

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  • Yet another Rails routing question

    - by danhere
    I can't seem to grasp the Rails routing just yet. I want to be able to link the site to, for example, ...com/store/xbox360/Mass Effect 2 (which is /store(my controller)/:system/:title). I have the database entries that include the :system and :title variables (?). How would I route these to show up and filter these entries? Or is this something I need to set up in the controller? I'm lost. Thanks so much for your help.

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  • Initialisation of Objects Syntax question

    - by Brock Woolf
    When I initialise a struct in C (Node is the struct): struct Node { /* Non-Relevant code */ }; This works: Node *rootNode = new Node(); but so does this: Node *rootNode = new Node; Is there a difference, and what is the difference between using () or not using the brackets? Just off memory, I think the same applies above for C++ object initialisations. What is happening here?

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  • Motherboard memory question

    - by JERiv
    I am currently drawing up specs on a new workstation for my office. I am considering the Asus P6X58D for a motherboard. This board's specs list it as supporting 24 gigs of memory. Suppose I were to use six four gig memory cards and then two video cards with 1 gig of memory apiece. Is the maximum supported memory similar to how 32 bit operating systems only have enough address space for 4 gigs of memory? Simply: Will the board post? If so, will the system be able to address all the memory, both the 24 gigs on the ddr3 bus and the 3 gigs on the graphics card?

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  • Database scaling question

    - by Anthony
    My app has outgrown just the one vps server (using Mediatemple DV). I want to put the database on another server. Does it have to be another Mediatemple server? Is it possible to use another hosting company and will the connections across the internet cause a slowdown if I choose to use say Rackspace or Linode for the DB server? btw, using mysql

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  • postgreSQL - pg_class question

    - by Sachin Chourasiya
    PostgreSQL stores statistics about tables in the system table called pg_class. The query planner accesses this table for every query. These statistics may only be updated using the analyze command. If the analyze command is not run often, the statistics in this table may not be accurate and the query planner may make poor decisions which can degrade system performance. Another strategy is for the query planner to generate these statistics for each query (including selects, inserts, updates, and deletes). This approach would allow the query planner to have the most up-to-date statistics possible. Why postgres always rely on pg_class instead?

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  • Simple stupid foreach loop question

    - by user281180
    In the code below i`m trying to read a list of selected projects and a list of all projects available. I want to store the all the projects that have not been selected from the list of all projects. But with the code below, I`m having list of all projects...Where and how to break the second loop incase projectId.Value == selectedProjectId.Value ? public IEnumerable NotselectedProjects; public IEnumerable NotSelectedProjects() { if (this.NotselectedProjects == null) { List<SelectListItem> result = new List<SelectListItem>(); foreach (var selectedProjectId in selectedProjects) { foreach (var projectId in projectLists) { if (projectId.Value != selectedProjectId.Value) { result.Add(new SelectListItem { Selected = false, Text = projectId.Text, Value = projectId.Value }); this.NotselectedProjects = result.AsEnumerable(); } } } } return this.NotselectedProjects; }

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  • Solr security question

    - by Camran
    I have a linux server, and I am about to upload a classifieds website to it. The website is php based. That means php code adds/removes classifieds, with the help of the users offcourse. The php-code then adds/removes a classified to a database index called Solr (like MySql). Problem is that anybody can currently access the database, but I only want the website to access the database (solr). Solr is on port 8983 as standard btw. My Q is, if I add a rule in my firewall (iptables), to only allow connections coming from the servers IP to the Solr port nr, would this solve my issue? Thanks

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