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  • Get to No as fast as possible

    - by Tim Hibbard
    There is a sales technique where the strategy is to get the customer to say “No deal” as soon as possible.  The idea being that by establishing terms that your customer is not comfortable with with, the sooner you can figure out what they will be willing to agree to.  The same principal can be applied to code design.  Instead of nested if…then statements, a code block should quickly eliminate the cases it is not equipped to handle and just focus on what it is meant to handle. This is code that will quickly become maintainable as requirements change: private void SaveClient(Client c) { if (c != null) { if (c.BirthDate != DateTime.MinValue) { foreach (Sale s in c.Sales) { if (s.IsProcessed) { SaveSaleToDatabase(s); } } SaveClientToDatabase(c); } } }   If an additional requirement comes along that requires the Client to have Manager approval or for a Sale to be under $20K, this code will get messy and unreadable. A better way to meet the same requirements would be: private void SaveClient(Client c) { if (c == null) { return; } if (c.BirthDate == DateTime.MinValue) { return; }   foreach (Sale s in c.Save) { if (!s.IsProcessed) { continue; } SaveSaleToDatabase(s); } SaveClientToDatabase(c); } This technique moves on quickly when it finds something it doesn’t like.  This makes it much easier to add a Manager approval constraint.  We would just insert the new requirement before the action takes place.

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  • Best way to mask 2D sprites in XNA?

    - by electroflame
    I currently am trying to mask some sprites. Rather than explaining it in words, I've made up some example pictures: The area to mask (in white) Now, the red sprite that needs to be cropped. The final result. Now, I'm aware that in XNA you can do two things to accomplish this: Use the Stencil Buffer. Use a Pixel Shader. I have tried to do a pixel shader, which essentially did this: float4 main(float2 texCoord : TEXCOORD0) : COLOR0 { float4 tex = tex2D(BaseTexture, texCoord); float4 bitMask = tex2D(MaskTexture, texCoord); if (bitMask.a > 0) { return float4(tex.r, tex.g, tex.b, tex.a); } else { return float4(0, 0, 0, 0); } } This seems to crop the images (albeit, not correct once the image starts to move), but my problem is that the images are constantly moving (they aren't static), so this cropping needs to be dynamic. Is there a way I could alter the shader code to take into account it's position? Alternatively, I've read about using the Stencil Buffer, but most of the samples seem to hinge on using a rendertarget, which I really don't want to do. (I'm already using 3 or 4 for the rest of the game, and adding another one on top of it seems overkill) The only tutorial I've found that doesn't use Rendertargets is one from Shawn Hargreaves' blog over here. The issue with that one, though is that it's for XNA 3.1, and doesn't seem to translate well to XNA 4.0. It seems to me that the pixel shader is the way to go, but I'm unsure of how to get the positioning correct. I believe I would have to change my onscreen coordinates (something like 500, 500) to be between 0 and 1 for the shader coordinates. My only problem is trying to work out how to correctly use the transformed coordinates. Thanks in advance for any help!

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  • Should I make a seperate unit test for a method, if it only modifies the parent state?

    - by Dante
    Should classes, that modify the state of the parent class, but not itself, be unit tested separately? And by separately, I mean putting the test in the corresponding unit test class, that tests that specific class. I'm developing a library based on chained methods, that return a new instance of a new type in most cases, where a chained method is called. The returned instances only modify the root parent state, but not itself. Overly simplified example, to get the point across: public class BoxedRabbits { private readonly Box _box; public BoxedRabbits(Box box) { _box = box; } public void SetCount(int count) { _box.Items += count; } } public class Box { public int Items { get; set; } public BoxedRabbits AddRabbits() { return new BoxedRabbits(this); } } var box = new Box(); box.AddRabbits().SetCount(14); Say, if I write a unit test under the Box class unit tests: box.AddRabbits().SetCount(14) I could effectively say, that I've already tested the BoxedRabbits class as well. Is this the wrong way of approaching this, even though it's far simpler to first write a test for the above call, then to first write a unit test for the BoxedRabbits separately?

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  • Performing a Depth First Search iteratively using async/parallel processing?

    - by Prabhu
    Here is a method that does a DFS search and returns a list of all items given a top level item id. How could I modify this to take advantage of parallel processing? Currently, the call to get the sub items is made one by one for each item in the stack. It would be nice if I could get the sub items for multiple items in the stack at the same time, and populate my return list faster. How could I do this (either using async/await or TPL, or anything else) in a thread safe manner? private async Task<IList<Item>> GetItemsAsync(string topItemId) { var items = new List<Item>(); var topItem = await GetItemAsync(topItemId); Stack<Item> stack = new Stack<Item>(); stack.Push(topItem); while (stack.Count > 0) { var item = stack.Pop(); items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } } return items; } I was thinking of something along these lines, but it's not coming together: var tasks = stack.Select(async item => { items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } }).ToList(); if (tasks.Any()) await Task.WhenAll(tasks); The language I'm using is C#.

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  • World Location issues with camera and particle

    - by Joe Weeks
    I have a bit of a strange question, I am adapting the existing code base including the tile engine as per the book: XNA 4.0 Game Development by example by Kurt Jaegers, particularly the aspect that I am working on is the part about the 2D platformer in the last couple of chapters. I am creating a platformer which has a scrolling screen (similar to an old school screen chase), I originally did not have any problems with this aspect as it is simply a case of updating the camera position on the X axis with game time, however I have since added a particle system to allow the players to fire weapons. This particle shot is updated via the world position, I have translated everything correctly in terms of the world position when the collisions are checked. The crux of the problem is that the collisions only work once the screen is static, whilst the camera is moving to follow the player, the collisions are offset and are hitting blocks that are no longer there. My collision for particles is as follows (There are two vertical and horizontal): protected override Vector2 horizontalCollisionTest(Vector2 moveAmount) { if (moveAmount.X == 0) return moveAmount; Rectangle afterMoveRect = CollisionRectangle; afterMoveRect.Offset((int)moveAmount.X, 0); Vector2 corner1, corner2; // new particle world alignment code. afterMoveRect = Camera.ScreenToWorld(afterMoveRect); // end. if (moveAmount.X < 0) { corner1 = new Vector2(afterMoveRect.Left, afterMoveRect.Top + 1); corner2 = new Vector2(afterMoveRect.Left, afterMoveRect.Bottom - 1); } else { corner1 = new Vector2(afterMoveRect.Right, afterMoveRect.Top + 1); corner2 = new Vector2(afterMoveRect.Right, afterMoveRect.Bottom - 1); } Vector2 mapCell1 = TileMap.GetCellByPixel(corner1); Vector2 mapCell2 = TileMap.GetCellByPixel(corner2); if (!TileMap.CellIsPassable(mapCell1) || !TileMap.CellIsPassable(mapCell2)) { moveAmount.X = 0; velocity.X = 0; } return moveAmount; } And the camera is pretty much the same as the one in the book... with this added (as an early test). public static void Update(GameTime gameTime) { position.X += 1; }

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  • Problem with a* implementation in pygame

    - by piyush3dxyz
    Yesterday i decide to make RTS game in pygame(pygame is best).I figured out many components of RTS game like unit selecting,health,resources but only 1 thing i still not understand.. which is a* pathfinding in pygame... I also done little bit of research on wiki,articles and papers...but still cant figure out problem.... function A*(start,goal) closedset := the empty set // The set of nodes already evaluated. openset := {start} // The set of tentative nodes to be evaluated, initially containing the start node came_from := the empty map // The map of navigated nodes. g_score[start] := 0 // Cost from start along best known path. // Estimated total cost from start to goal through y. f_score[start] := g_score[start] + heuristic_cost_estimate(start, goal) while openset is not empty current := the node in openset having the lowest f_score[] value if current = goal return reconstruct_path(came_from, goal) remove current from openset add current to closedset for each neighbor in neighbor_nodes(current) if neighbor in closedset continue tentative_g_score := g_score[current] + dist_between(current,neighbor) if neighbor not in openset or tentative_g_score <= g_score[neighbor] came_from[neighbor] := current g_score[neighbor] := tentative_g_score f_score[neighbor] := g_score[neighbor] + heuristic_cost_estimate(neighbor, goal) if neighbor not in openset add neighbor to openset return failure here is the pseudocode for wiki a* implementation......

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  • Collision detection between a sprite and rectangle in canvas

    - by Andy
    I'm building a Javascript + canvas game which is essentially a platformer. I have the player all set up and he's running, jumping and falling, but I'm having trouble with the collision detection between the player and blocks (the blocks will essentially be the platforms that the player moves on). The blocks are stored in an array like this: var blockList = [[50, 400, 100, 100]]; And drawn to the canvas using this: this.draw = function() { c.fillRect(blockList[0][0], blockList[0][1], 100, 100); } I'm checking for collisions using something along these lines in the player object: this.update = function() { // Check for collitions with blocks for(var i = 0; i < blockList.length; i++) { if((player.xpos + 34) > blockList[i][0] && player.ypos > blockList[i][1]) { player.xpos = blockList[i][0] - 28; return false; } } // Other code to move the player based on keyboard input etc } The idea is if the player will collide with a block in the next game update (the game uses a main loop running at 60Htz), the function will return false and exit, thus meaning the player won't move. Unfortunately, that only works when the player hits the left side of the block, and I can't work out how to make it so the player stops if it hits any side of the block. I have the properties player.xpos and player.ypos to help here.

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  • What is the value of checking in failing unit tests?

    - by Adam W.
    While there are ways of keeping unit tests from being executed, what is the value of checking in failing unit tests? I will use a simple example: Case Sensitivity. The current code is case sensitive. A valid input into the method is "Cat" and it would return an enum of Animal.Cat. However, the desired functionality of the method should not be case sensitive. So if the method described was passed "cat" it could possibly return something like Animal.Null instead of Animal.Cat and the unit test would fail. Though a simple code change would make this work, a more complex issue may take weeks to fix, but identifying the bug with a unit test could be a less complex task. The application currently being analyzed has 4 years of code that "works". However, recent discussions regarding unit tests have found flaws in the code. Some just need explicit implementation documentation (ex. case sensitive or not), or code that does not execute the bug based on how it is currently called. But unit tests can be created executing specific scenarios that will cause the bug to be seen and are valid inputs. What is the value of checking in unit tests that exercise the bug until someone can get around to fixing the code? Should this unit test be flagged with ignore, priority, category etc, to determine whether a build was successful based on tests executed? Eventually the unit test should be created to execute the code once someone fixes it. On one hand it shows that identified bugs have not been fixed. On the other, there could be hundreds of failed unit tests showing up in the logs and weeding through the ones that should fail vs. failures due to a code check-in would be difficult to find.

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  • SQL language drawbacks, The Third Manifesto

    - by David Portabella
    Sometime ago I read about SQL language drawbacks (the basic language specification, not vendor specific), and one of the drawbacks was that the language does not allow to create a set of tuples that don't come from a table. For instance, SELECT firstName, lastName from people; this creates a set of tuples coming from the table people. Now, if I don't have this table people, and I want to return a constant, I'd need something like this to return a set of two tuples (this would not require to have a table): SELECT VALUES('james', 'dean'), ('tom', 'cruisse'); Why I would need that? Because of the same reasons that we can define constants (not only basic types, but objects and arrays also) in any advanced programming language. Workarounds, Yes, I could create a temporal table, fill the data, and SELECT from that table. This is a hack, to overcome the drawbacks of the poor SQL language. I think that I read about this somewhere in "The Third Manifesto", but I don't find the paragraph/example talking about this concrete drawback anymore. Do you know a reference about it?

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  • Gathering IP address and workstation information; does it belong in a state class?

    - by p.campbell
    I'm writing an enterprisey utility that collects exception information and writes to the Windows Event Log, sends an email, etc. This utility class will be used by all applications in the corporation: web, BizTalk, Windows Services, etc. Currently this class: holds state given to it via public properties calls out to .NET Framework methods to gather information about runtime details. Included are call to various properties and methods from System.Environment, Reflection details, etc. This implementation has the benefit of allowing all those callers not to have to make these same calls themselves. This means less code for the caller to forget, screw up, etc. Should this state class (please what's the phrase I'm looking for [like DTO]?) know how to resolve/determine runtime details (like the IP address and machine name that it's running on)? It seems to me on second thought that it's meant to be a class that should hold state, and not know how to call out to the .NET Framework to find information. var myEx = new AppProblem{MachineName="Riker"}; //Will get "Riker 10.0.0.1" from property MachineLongDesc Console.WriteLine("full machine details: " + myEx.MachineLongDesc); public class AppProblem { public string MachineName{get;set;} public string MachineLongDesc{ get{ if(string.IsNullOrEmpty(this.MachineName) { this.MachineName = Environment.MachineName; } return this.MachineName + " " + GetCurrentIP(); } } private string GetCurrentIP() { return System.Net.Dns.GetHostEntry(this.MachineName) .AddressList.First().ToString(); } } This code was written by hand from memory, and presented for simplicity, trying to illustrate the concept.

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  • MultiSelectChoice: How to get underlying values selected

    - by Vijay Mohan
    Let's say you include a multiselectchoice component in your jspx/jsff page, which has <f;selectItem> or <af:forEach> binded to a VO iterator to populate the multiselectchoice and the value property of which is binded to a List attribute binding.When the user selects some items in that choice List then u want the actual values to be posted.You can check the valuepassthrough flag to true , but many a times it doesn't help and you end up getting the indexes of multiselect values.Here is a way to get the actual values..Lets say in the bean u have a utility method to achieve this as follows..You can associate a valueChangeListener for the multiselectchoice as follows..public void onValueChangeOfLOV(ValueChangeEvent valueChangeEvent) { //get array of indexes of selected items in master list List valueIndexes = (List)valueChangeEvent.getNewValue(); String concatCodes = returnSelectmanyChoiceValues(valueIndexes,"YourIterator", "YourAttribute"); } public String returnSelectmanyChoiceValues(List valueIndexes,String iterName, String idAttrName){ DCBindingContainer dc = (DCBindingContainer)BindingContext.getCurrent().getCurrentBindingsEntry(); DCIteratorBinding iter = dc.findIteratorBinding(iterName); ViewObject vo = iter.getViewObject(); String codes = ""; for(Object index : valueIndexes){ String iIndex = (String)index; Row row = vo.getRowAtRangeIndex(Integer.parseInt(iIndex)); codes = codes +(String)row.getAttribute(idAttrName)+","; } //remove last "," if(codes.endsWith(",")) codes = codes.substring(0,codes.lastIndexOf(",")); return codes; }This will return u a comma separated values of the selected items. if you want thenYou can store it in a List.

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  • Entity Framework and layer separation

    - by Thomas
    I'm trying to work a bit with Entity Framework and I got a question regarding the separation of layers. I usually use the UI - BLL - DAL approach and I'm wondering how to use EF here. My DAL would usually be something like GetPerson(id) { // some sql return new Person(...) } BLL: GetPerson(id) { Return personDL.GetPerson(id) } UI: Person p = personBL.GetPerson(id) My question now is: since EF creates my model and DAL, is it a good idea to wrap EF inside my own DAL or is it just a waste of time? If I don't need to wrap EF would I still place my Model.esmx inside its own class library or would it be fine to just place it inside my BLL and work some there? I can't really see the reason to wrap EF inside my own DAL but I want to know what other people are doing. So instead of having the above, I would leave out the DAL and just do: BLL: GetPerson(id) { using (TestEntities context = new TestEntities()) { var result = from p in context.Persons.Where(p => p.Id = id) select p; } } What to do?

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  • Pure functional programming and game state

    - by Fu86
    Is there a common technique to handle state (in general) in a functional programming language? There are solutions in every (functional) programming language to handle global state, but I want to avoid this as far as I could. All state in a pure functional manner are function parameters. So I need to put the whole game state (a gigantic hashmap with the world, players, positions, score, assets, enemies, ...)) as a parameter to all functions which wants to manipulate the world on a given input or trigger. The function itself picks the relevant information from the gamestate blob, do something with it, manipulate the gamestate and return the gamestate. But this looks like a poor mans solution for the problem. If I put the whole gamestate into all functions, there is no benefit for me in contrast to global variables or the imperative approach. I could put just the relevant information into the functions and return the actions which will be taken for the given input. And one single function apply all the actions to the gamestate. But most functions need a lot of "relevant" information. move() need the object position, the velocity, the map for collision, position of all enemys, current health, ... So this approach does not seem to work either. So my question is how do I handle the massive amount of state in a functional programming language -- especially for game development?

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  • MVC pattern synchronisation

    - by Hariprasad
    I am facing a problem in synchronizing my model and view threads I have a view which is table. In it, user can select a few rows. I update the view as soon as the user clicks on any row since I don't want the UI to be slow. This updating is done by a logic which runs in the controller thread below. At the same time, the controller will update the model data too, which takes place in a different thread. i.e., controller puts the query in a queue, which is then executed by the model thread - which is a single-threaded interface. As soon as the query executes, controller will get a signal. Now, In order to keep the view and model synchronized, I will update the view again based on the return value of the query (the data returned by model) - even though I updated the view already for that user action. But, I am facing issues because, its taking a lot of time for the model to return the result, by that time user would have performed multiple clicks. So, as a result of updating the view again based on the information from model, the view sometimes goes back to the state in which the previous clicks were made (Suppose user clicks thrice on different rows. I update the view as soon as the click happens. Also, I update the view when I get data back from the model - which is supposed to be same as the already updated state of the view. Now, when the user clicks third time, I get data for the first click from model. As a result, view goes back to a state which is generated by the first click) Is there any way to handle such a synchronization issue?

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  • How do you proactively guard against errors of omission?

    - by Gabriel
    I'll preface this with I don't know if anyone else who's been programming as long as I have actually has this problem, but at the very least, the answer might help someone with less xp. I just stared at this code for 5 minutes, thinking I was losing my mind that it didn't work: var usedNames = new HashSet<string>(); Func<string, string> l = (s) => { for (int i = 0; ; i++) { var next = (s + i).TrimEnd('0'); if (!usedNames.Contains(next)) { return next; } } }; Finally I noticed I forgot to add the used name to the hash set. Similarly, I've spent minutes upon minutes over omitting context.SaveChanges(). I think I get so distracted by the details that I'm thinking about that some really small details become invisible to me - it's almost at the level of mental block. Are there tactics to prevent this? update: a side effect of asking this was fixing the error it would have for i 9 (Thanks!) var usedNames = new HashSet<string>(); Func<string, string> name = (s) => { string result = s; if(usedNames.Contains(s)) for (int i = 1; ; result = s + i++) if (!usedNames.Contains(result)) break; usedNames.Add(result); return result; };

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  • How to set permalink of your blog post according to date and title of post?

    - by Amit
    I am having this website http://www.finalyearondesk.com . My blogs post link are set like this.. http://www.finalyearondesk.com/index.php?id=28 . I want it to set like this ... finalyearondesk.com/2011/09/22/how-to-recover-ubuntu-after-it-is-crashed/ . I am using the following function to get these posts... function get_content($id = '') { if($id != ""): $id = mysql_real_escape_string($id); $sql = "SELECT * from blog WHERE id = '$id'"; $return = '<p><a href="http://www.finalyearondesk.com/">Go back to Home page</a></p>'; echo $return; else: $sql = "select * from blog ORDER BY id DESC"; endif; $res = mysql_query($sql) or die(mysql_error()); if(mysql_num_rows($res) != 0): while($row = mysql_fetch_assoc($res)) { echo '<h1><a href="index.php?id=' . $row['id'] . '">' . $row['title'] . '</a></h1>'; echo '<p>' . "By: " . '<font color="orange">' . $row['author'] . '</font>' . ", Posted on: " . $row['date'] . '<p>'; echo '<p>' . $row['body'] . '</p><br />'; } else: echo '<p>We are really very sorry, this page does not exist!</p>'; endif; } Any suggestions how to do this? And can we do this by using .htaccess?

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  • Using ConcurrentQueue for thread-safe Performance Bookkeeping.

    - by Strenium
    Just a small tidbit that's sprung up today. I had to book-keep and emit diagnostics for the average thread performance in a highly-threaded code over a period of last X number of calls and no more. Need of the day: a thread-safe, self-managing stats container. Since .NET 4.0 introduced new thread-safe 'Collections.Concurrent' objects and I've been using them frequently - the one in particular seemed like a good fit for storing each threads' performance data - ConcurrentQueue. But I wanted to store only the most recent X# of calls and since the ConcurrentQueue currently does not support size constraint I had to come up with my own generic version which attempts to restrict usage to numeric types only: unfortunately there is no IArithmetic-like interface which constrains to only numeric types – so the constraints here here aren't as elegant as they could be. (Note the use of the Average() method, of course you can use others as well as make your own).   FIFO FixedSizedConcurrentQueue using System;using System.Collections.Concurrent;using System.Linq; namespace xxxxx.Data.Infrastructure{    [Serializable]    public class FixedSizedConcurrentQueue<T> where T : struct, IConvertible, IComparable<T>    {        private FixedSizedConcurrentQueue() { }         public FixedSizedConcurrentQueue(ConcurrentQueue<T> queue)        {            _queue = queue;        }         ConcurrentQueue<T> _queue = new ConcurrentQueue<T>();         public int Size { get { return _queue.Count; } }        public double Average { get { return _queue.Average(arg => Convert.ToInt32(arg)); } }         public int Limit { get; set; }        public void Enqueue(T obj)        {            _queue.Enqueue(obj);            lock (this)            {                T @out;                while (_queue.Count > Limit) _queue.TryDequeue(out @out);            }        }    } }   The usage case is straight-forward, in this case I’m using a FIFO queue of maximum size of 200 to store doubles to which I simply Enqueue() the calculated rates: Usage var RateQueue = new FixedSizedConcurrentQueue<double>(new ConcurrentQueue<double>()) { Limit = 200 }; /* greater size == longer history */   That’s about it. Happy coding!

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  • How to Avoid a Busy Loop Inside a Function That Returns the Object That's Being Waited For

    - by Carl Smith
    I have a function which has the same interface as Python's input builtin, but it works in a client-server environment. When it's called, the function, which runs in the server, sends a message to the client, asking it to get some input from the user. The user enters some stuff, or dismisses the prompt, and the result is passed back to the server, which passes it to the function. The function then returns the result. The function must work like Python's input [that's the spec], so it must block until it has the result. This is all working, but it uses a busy loop, which, in practice, could easily be spinning for many minutes. Currently, the function tells the client to get the input, passing an id. The client returns the result with the id. The server puts the result in a dictionary, with the id as the key. The function basically waits for that key to exist. def input(): '''simplified example''' key = unique_key() tell_client_to_get_input(key) while key not in dictionary: pass return dictionary.pop(pin) Using a callback would be the normal way to go, but the input function must block until the result is available, so I can't see how that could work. The spec can't change, as Python will be using the new input function for stuff like help and pdb, which provide their own little REPLs. I have a lot of flexibility in terms of how everything works overall, but just can't budge on the function acting exactly like Python's. Is there any way to return the result as soon as it's available, without the busy loop?

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  • JQuery Validation dates [migrated]

    - by james
    Im trying to get my form to validate...so basically its working, but a little bit too well, I have two text boxes, one is a start date, the other an end date in the format of mm/dd/yyyy if the start date is greater than the end date...there is an error if the end date is less than the start date...there is an error if the start date is less than today's date...there is an error The only thing is when I correct the error, the error warning is still there...here is my code: // Validate Date Ranges if ($(this).val() != '' && dates.not(this).val != '') { if ($(this).hasClass("FromCal")) { if (new Date(testDate) > new Date(otherDate)) { addError($(this)); $('.flightDateError').text('* Start date must be earlier than end date.'); isValid = false; return; } } else { if (new Date(testDate) < new Date(otherDate)) { addError($(this)); $('.flightDateError').text('* End date must be later than start date.'); return; } } } and here are the two text boxes: <div id="campaign_start" style="display: inline-block"> <label class="date_range_label">from:</label> <asp:TextBox ID="FromCalTbx" runat="server" Width="100px" CssClass="FromCal editable float_left required" /> </div> <div id="campaign_end" style="display: inline-block"> <label class="date_range_label">to:</label> <asp:TextBox ID="ToCalTbx" runat="server" Width="100px" CssClass="float_left optional"/> </div> PS - testDate is the start Date otherDate is the end Date

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  • Making a class pseudo-immutable by setting a flag

    - by scott_fakename
    I have a java project that involves building some pretty complex objects. There are quite a lot (dozens) of different ones and some of them have a HUGE number of parameters. They also need to be immutable. So I was thinking the builder pattern would work, but it ends up require a lot of boilerplate. Another potential solution I thought of was to make a mutable class, but give it a "frozen" flag, a-la ruby. Here is a simple example: public class EqualRule extends Rule { private boolean frozen; private int target; public EqualRule() { frozen = false; } public void setTarget(int i) { if (frozen) throw new IllegalStateException( "Can't change frozen rule."); target = i; } public int getTarget() { return target; } public void freeze() { frozen = true; } @Override public boolean checkRule(int i) { return (target == i); } } and "Rule" is just an abstract class that has an abstract "checkRule" method. This cuts way down on the number of objects I need to write, while also giving me an object that becomes immutable for all intents and purposes. This kind of act like the object was its own Builder... But not quite. I'm not too excited, however, about having an immutable being disguised as a bean however. So I had two questions: 1. Before I go too far down this path, are there any huge problems that anyone sees right off the bat? For what it's worth, it is planned that this behavior will be well documented... 2. If so, is there a better solution? Thanks

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  • Calling a webservice via Javascript

    - by jeroenb
    If you want to consume a webservice, it's not allways necessary to do a postback. It's even not that hard! 1. Webservice You have to add the scriptservice attribute to the webservice. [System.Web.Script.Services.ScriptService]public class PersonsInCompany : System.Web.Services.WebService { Create a WebMethod [WebMethod] public Person GetPersonByFirstName(string name) { List<Person> personSelect = persons.Where(p => p.FirstName.ToLower().StartsWith(name.ToLower())).ToList(); if (personSelect.Count > 0) return personSelect.First(); else return null; } 2. webpage Add reference to your service to your scriptmanager <script type="text/javascript"> function GetPersonInCompany() { var val = document.getElementById("MainContent_TextBoxPersonName"); PersonsInCompany.GetPersonByFirstName(val.value, FinishCallback); } function FinishCallback(result) { document.getElementById("MainContent_LabelFirstName").innerHTML = result.FirstName; document.getElementById("MainContent_LabelName").innerHTML = result.Name; document.getElementById("MainContent_LabelAge").innerHTML = result.Age; document.getElementById("MainContent_LabelCompany").innerHTML = result.Company; } </script> Add some javascript, where you first call your webservice. Classname.Webmethod = PersonsInCompany.GetPersonByFirstName Add a callback to catch the result from the webservice. And use the result to update your page. <script type="text/javascript"> function GetPersonInCompany() { var val = document.getElementById("MainContent_TextBoxPersonName"); PersonsInCompany.GetPersonByFirstName(val.value, FinishCallback); } function FinishCallback(result) { document.getElementById("MainContent_LabelFirstName").innerHTML = result.FirstName; document.getElementById("MainContent_LabelName").innerHTML = result.Name; document.getElementById("MainContent_LabelAge").innerHTML = result.Age; document.getElementById("MainContent_LabelCompany").innerHTML = result.Company; } </script>   If you have any question, feel free to contact me! You can download the code here.

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  • Reasons behind polymorphism related behaviour in java

    - by Shades88
    I read this code somewhere class Foo { public int a; public Foo() { a = 3; } public void addFive() { a += 5; } public int getA() { System.out.println("we are here in base class!"); return a; } } public class Polymorphism extends Foo{ public int a; public Poylmorphism() { a = 5; } public void addFive() { System.out.println("we are here !" + a); a += 5; } public int getA() { System.out.println("we are here in sub class!"); return a; } public static void main(String [] main) { Foo f = new Polymorphism(); f.addFive(); System.out.println(f.getA()); // SOP 1 System.out.println(f.a); // SOP 2 } } For SOP1 we get answer 10 and for SOP2 we get answer 3. Reason for this is that you can't override variables whereas you can do so for methods. This happens because type of the reference variable is checked when a variable is accessed and type of the object is checked when a method is accessed. But I am wondering, just why is it that way? Can anyone explain me what is the reason for this behaviour

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  • Search multiple tables

    - by gilden
    I have developed a web application that is used mainly for archiving all sorts of textual material (documents, references to articles, books, magazines etc.). There can be any given number of archive tables in my system, each with its own schema. The schema can be changed by a moderator through the application (imagine something similar to a really dumbed down version of phpMyAdmin). Users can search for anything from all of the tables. By using FULLTEXT indexes together with substring searching (fields which do not support FULLTEXT indexing) the script inserts the results of a search to a single table and by ordering these results by the similarity measure I can fairly easily return the paginated results. However, this approach has a few problems: substring searching can only count exact results the 50% rule applies to all tables separately and thus, mysql may not return important matches or too naively discards common words. is quite expensive in terms of query numbers and execution time (not an issue right now as there's not a lot of data yet in the tables). normalized data is not even searched for (I have different tables for categories, languages and file attatchments). My planned solution Create a single table having columns similar to id, table_id, row_id, data Every time a new row is created/modified/deleted in any of the data tables this central table also gets updated with the data column containing a concatenation of all the fields in a row. I could then create a single index for Sphinx and use it for doing searches instead. Are there any more efficient solutions or best practises how to approach this? Thanks.

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  • Getting Center and Radius of Irregural Object

    - by Moaz ELdeen
    I have drawn an asteroid object manually , and would like to get its center/radius by a specific equation. I think I can get them by calculated and hard-coded values. The code to draw the asteroid: void Asteroid::Draw() { float ratio = app::getWindowWidth()/app::getWindowHeight(); gl::pushMatrices(); gl::translate(m_Pos*ratio); gl::scale(3.5*ratio,3.5*ratio,3.5*ratio); gl::color(ci::Color(1,1,1)); gl::drawLine(Vec2f(-15,0),Vec2f(-10,-5)); gl::drawLine(Vec2f(-10,-5),Vec2f(-5,-5)); gl::drawLine(Vec2f(-5,-5),Vec2f(-5,-8)); gl::drawLine(Vec2f(-5,-8),Vec2f(5,-8)); gl::drawLine(Vec2f(5,-8),Vec2f(5,-5)); gl::drawLine(Vec2f(5,-5),Vec2f(10,-5)); gl::drawLine(Vec2f(10,-5),Vec2f(15,0)); gl::drawLine(Vec2f(15,0),Vec2f(10,5)); gl::drawLine(Vec2f(10,5),Vec2f(-10,5)); gl::drawLine(Vec2f(-10,5),Vec2f(-10,5)); gl::drawLine(Vec2f(-15,0),Vec2f(-10,5)); gl::popMatrices(); } According to the answer I have written that code to calculate the radius, is it correct or not ? cinder::Vec2f Asteroid::getCenter() { return ci::Vec2f(m_Pos.x, m_Pos.y); } double Asteroid::getRadius() { ci::Vec2f _vec = (getCenter()- Vec2f(15,5)); return _vec.length()*0.3f; }

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  • Should this code/logic be included in Business Objects class or a separate class?

    - by aspdotnetuser
    I have created a small application which has a three tier architecture and I have business object classes to represent entities such as User, Orders, UserType etc. In these classes I have methods that are executed when the Constuctor method of, for example, User is called. These methods perform calculations and generate details that setup data for attributes that are part of each User object. Here is the structure for the project in Visual Studio: Here is some code from the business object class User.cs: Public Class User { public string Name { get; set; } public int RandomNumber { get; set; } etc public User { Name = GetName(); RandomNumber = GetRandomNumber(); } public string GetName() { .... return name; } public int GetRandomNumber() { ... return randomNumber; } } Should this logic be included in the Business Object classes or should it be included in a Utilities class of some kind? Or in the business rules?

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