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  • Performance of String literals vs constants for Session[...] dictionary keys

    - by FreshCode
    Session[Constant] vs Session["String Literal"] Performance I'm retrieving user-specific data like ViewData["CartItems"] = Session["CartItems"]; with a string literal for keys on every request. Should I be using constants for this? If yes, how should I go about implementing frequently used string literals and will it significantly affect performance on a high-traffic site? Related question does not address ASP.NET MVC or Session.

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  • How do I sum values from two dictionaries in C#?

    - by George Stocker
    I have two dictionaries with the same structure: Dictionary<string, int> foo = new Dictionary<string, int>() { {"Table", 5 }, {"Chair", 3 }, {"Couch", 1 } }; Dictionary<string, int> bar = new Dictionary<string, int>() { {"Table", 4 }, {"Chair", 7 }, {"Couch", 8 } }; I'd like to sum the values of the dictionaries together and return a third dictionaries with the keys, and the total values for each key: Table, 9 Chair, 10 Couch, 9 My current solution is to loop through the dictionary and pull them out that way, but I know that solution isn't the most performant or most readable. However, I'm hitting a brick wall trying to come up with a solution in LINQ.

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  • How can I make this Dictionary TryGetValue code more readable?

    - by mafutrct
    I'd like to test if an id was not yet known or, if it is known, if the associated value has changed. I'm currently using code similar to this, but it is hard to understand for those not familiar with the pattern. Can you think of a way to make it more readable while keeping it short in LOC? string id; string actual; string stored; if (!someDictionary.TryGetValue (id, out stored) || stored != actual) { // id not known yet or associated value changed. }

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  • smarter "reverse" of a dictionary in python (acc for some of values being the same)?

    - by mrkafk
    def revert_dict(d): rd = {} for key in d: val = d[key] if val in rd: rd[val].append(key) else: rd[val] = [key] return rd >>> revert_dict({'srvc3': '1', 'srvc2': '1', 'srvc1': '2'}) {'1': ['srvc3', 'srvc2'], '2': ['srvc1']} This obviously isn't simple exchange of keys with values: this would overwrite some values (as new keys) which is NOT what I'm after. If 2 or more values are the same for different keys, keys are supposed to be grouped in a list. The above function works, but I wonder if there is a smarter / faster way?

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  • Generating a .CSV with Several Columns - Use a Dictionary?

    - by Qanthelas
    I am writing a script that looks through my inventory, compares it with a master list of all possible inventory items, and tells me what items I am missing. My goal is a .csv file where the first column contains a unique key integer and then the remaining several columns would have data related to that key. For example, a three row snippet of my end-goal .csv file might look like this: 100001,apple,fruit,medium,12,red 100002,carrot,vegetable,medium,10,orange 100005,radish,vegetable,small,10,red The data for this is being drawn from a couple sources. 1st, a query to an API server gives me a list of keys for items that are in inventory. 2nd, I read in a .csv file into a dict that matches keys with item name for all possible keys. A snippet of the first 5 rows of this .csv file might look like this: 100001,apple 100002,carrot 100003,pear 100004,banana 100005,radish Note how any key in my list of inventory will be found in this two column .csv file that gives all keys and their corresponding item name and this list minus my inventory on hand yields what I'm looking for (which is the inventory I need to get). So far I can get a .csv file that contains just the keys and item names for the items that I don't have in inventory. Give a list of inventory on hand like this: 100003,100004 A snippet of my resulting .csv file looks like this: 100001,apple 100002,carrot 100005,radish This means that I have pear and banana in inventory (so they are not in this .csv file.) To get this I have a function to get an item name when given an item id that looks like this: def getNames(id_to_name, ids): return [id_to_name[id] for id in ids] Then a function which gives a list of keys as integers from my inventory server API call that returns a list and I've run this function like this: invlist = ServerApiCallFunction(AppropriateInfo) A third function takes this invlist as its input and returns a dict of keys (the item id) and names for the items I don't have. It also writes the information of this dict to a .csv file. I am using the set1 - set2 method to do this. It looks like this: def InventoryNumbers(inventory): with open(csvfile,'w') as c: c.write('InvName' + ',InvID' + '\n') missinginvnames = [] with open("KeyAndItemNameTwoColumns.csv","rb") as fp: reader = csv.reader(fp, skipinitialspace=True) fp.readline() # skip header invidsandnames = {int(id): str.upper(name) for id, name in reader} invids = set(invidsandnames.keys()) invnames = set(invidsandnames.values()) invonhandset = set(inventory) missinginvidsset = invids - invonhandset missinginvids = list(missinginvidsset) missinginvnames = getNames(invidsandnames, missinginvids) missinginvnameswithids = dict(zip(missinginvnames, missinginvids)) print missinginvnameswithids with open(csvfile,'a') as c: for invname, invid in missinginvnameswithids.iteritems(): c.write(invname + ',' + str(invid) + '\n') return missinginvnameswithids Which I then call like this: InventoryNumbers(invlist) With that explanation, now on to my question here. I want to expand the data in this output .csv file by adding in additional columns. The data for this would be drawn from another .csv file, a snippet of which would look like this: 100001,fruit,medium,12,red 100002,vegetable,medium,10,orange 100003,fruit,medium,14,green 100004,fruit,medium,12,yellow 100005,vegetable,small,10,red Note how this does not contain the item name (so I have to pull that from a different .csv file that just has the two columns of key and item name) but it does use the same keys. I am looking for a way to bring in this extra information so that my final .csv file will not just tell me the keys (which are item ids) and item names for the items I don't have in stock but it will also have columns for type, size, number, and color. One option I've looked at is the defaultdict piece from collections, but I'm not sure if this is the best way to go about what I want to do. If I did use this method I'm not sure exactly how I'd call it to achieve my desired result. If some other method would be easier I'm certainly willing to try that, too. How can I take my dict of keys and corresponding item names for items that I don't have in inventory and add to it this extra information in such a way that I could output it all to a .csv file? EDIT: As I typed this up it occurred to me that I might make things easier on myself by creating a new single .csv file that would have date in the form key,item name,type,size,number,color (basically just copying in the column for item name into the .csv that already has the other information for each key.) This way I would only need to draw from one .csv file rather than from two. Even if I did this, though, how would I go about making my desired .csv file based on only those keys for items not in inventory?

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  • Stop a rotating object at a specified angle?

    - by Krummelz
    I'm working in JavaScript with HTML5 and the canvas. I have an object which is rotating at a certain speed, and I need the object's rotation to slow down gradually and the front of the object to stop at a specified angle. (I'm using radians, not degrees.) I have a variable to keep track of the angle which the object is facing, as it rotates. How would I go about getting the object to come to rest, facing the direction I want it to?

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  • Odd "Object reference not set to an instance of an object" involving xWinForms

    - by Kyle
    Hey, I've been trying to get the xWinForms 3.0 library (a library with forms support in xna) working with my C# XNA Game project but I keep getting the same problem. I add the reference to my project, put in the using statement, declare a formCollection variable and then I try to initialize it. whenever I run the project I get stopped on this line: formCollection = new FormCollection(this.Window, Services, ref graphics); it gives me the error: " System.NullReferenceException was unhandled Message="Object reference not set to an instance of an object." Source="Microsoft.Xna.Framework" StackTrace: at Microsoft.Xna.Framework.Graphics.VertexShader..ctor(GraphicsDevice graphicsDevice, Byte[] shaderCode) at Microsoft.Xna.Framework.Graphics.SpriteBatch.ConstructPlatformData() at Microsoft.Xna.Framework.Graphics.SpriteBatch..ctor(GraphicsDevice graphicsDevice) at xWinFormsLib.FormCollection..ctor(GameWindow window, IServiceProvider services, GraphicsDeviceManager& graphics) at GameSolution.Game2.LoadContent() in C:\Users\Owner\Documents\School\Year 3\Winter\Soen 390\TeamWTF_3\SourceCode\GameSolution\GameSolution\Game2.cs:line 45 at Microsoft.Xna.Framework.Game.Initialize() at GameSolution.Game2.Initialize() in C:\Users\Owner\Documents\School\Year 3\Winter\Soen 390\TeamWTF_3\SourceCode\GameSolution\GameSolution\Game2.cs:line 37 at Microsoft.Xna.Framework.Game.Run() at GameSolution.Program.Main(String[] args) in C:\Users\Owner\Documents\School\Year 3\Winter\Soen 390\TeamWTF_3\SourceCode\GameSolution\GameSolution\Program.cs:line 14 InnerException: " In a project I downloaded that used the xWinForms, I put the following code in and it compiled and ran no error. but when I put it in my project I get the error. Am I making some stupid mistake about including dlls or something? I've been at this for hours and I can't seem to find anything that would cause this. using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; using Microsoft.Xna.Framework.Net; using Microsoft.Xna.Framework.Storage; using xWinFormsLib; namespace GameSolution { public class Game2 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; FormCollection formCollection; public Game2() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } protected override void Initialize() { // TODO: Add your initialization logic here base.Initialize(); } protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); formCollection = new FormCollection(this.Window, Services, ref graphics); } protected override void Update(GameTime gameTime) { base.Update(gameTime); } protected override void Draw(GameTime gameTime) { base.Draw(gameTime); } } } Any help would be greatly appreciated ._.

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  • Need to cast to an object without knowing what type the object is

    - by jle
    I am trying to dynamically load my authentication server type based on a setting. I am hung up on how to cast to a type when I don't know the type. Type t = Type.GetType(WebConfigurationManager.AppSettings.Get("AuthenticationSvcImpl")); IAuthenticationService authCli = Activator.CreateInstance(t); return authCli.AuthenticateUser(login); I know there is Convert.ChangeType(), but that just converts to an object...

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  • Javascript: how to access anonymous object within object?

    - by Caballero
    I have a string generated by php's json_encode() that looks like this: [ { "key1":"value1", "key2":"value2", "key3":"value3" }, { "key1":"value1", "key2":"value2", "key3":"value3" } ] I use Javascript function to convert the string to Javascript object: var jsonObj=JSON.parse(string); How do I access the data inside since the inner objects have no names? I tried something like: alert(jsonObj.firstChild.key1); It gives me "undefined". Why is that so?

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  • C# 4: The Curious ConcurrentDictionary

    - by James Michael Hare
    In my previous post (here) I did a comparison of the new ConcurrentQueue versus the old standard of a System.Collections.Generic Queue with simple locking.  The results were exactly what I would have hoped, that the ConcurrentQueue was faster with multi-threading for most all situations.  In addition, concurrent collections have the added benefit that you can enumerate them even if they're being modified. So I set out to see what the improvements would be for the ConcurrentDictionary, would it have the same performance benefits as the ConcurrentQueue did?  Well, after running some tests and multiple tweaks and tunes, I have good and bad news. But first, let's look at the tests.  Obviously there's many things we can do with a dictionary.  One of the most notable uses, of course, in a multi-threaded environment is for a small, local in-memory cache.  So I set about to do a very simple simulation of a cache where I would create a test class that I'll just call an Accessor.  This accessor will attempt to look up a key in the dictionary, and if the key exists, it stops (i.e. a cache "hit").  However, if the lookup fails, it will then try to add the key and value to the dictionary (i.e. a cache "miss").  So here's the Accessor that will run the tests: 1: internal class Accessor 2: { 3: public int Hits { get; set; } 4: public int Misses { get; set; } 5: public Func<int, string> GetDelegate { get; set; } 6: public Action<int, string> AddDelegate { get; set; } 7: public int Iterations { get; set; } 8: public int MaxRange { get; set; } 9: public int Seed { get; set; } 10:  11: public void Access() 12: { 13: var randomGenerator = new Random(Seed); 14:  15: for (int i=0; i<Iterations; i++) 16: { 17: // give a wide spread so will have some duplicates and some unique 18: var target = randomGenerator.Next(1, MaxRange); 19:  20: // attempt to grab the item from the cache 21: var result = GetDelegate(target); 22:  23: // if the item doesn't exist, add it 24: if(result == null) 25: { 26: AddDelegate(target, target.ToString()); 27: Misses++; 28: } 29: else 30: { 31: Hits++; 32: } 33: } 34: } 35: } Note that so I could test different implementations, I defined a GetDelegate and AddDelegate that will call the appropriate dictionary methods to add or retrieve items in the cache using various techniques. So let's examine the three techniques I decided to test: Dictionary with mutex - Just your standard generic Dictionary with a simple lock construct on an internal object. Dictionary with ReaderWriterLockSlim - Same Dictionary, but now using a lock designed to let multiple readers access simultaneously and then locked when a writer needs access. ConcurrentDictionary - The new ConcurrentDictionary from System.Collections.Concurrent that is supposed to be optimized to allow multiple threads to access safely. So the approach to each of these is also fairly straight-forward.  Let's look at the GetDelegate and AddDelegate implementations for the Dictionary with mutex lock: 1: var addDelegate = (key,val) => 2: { 3: lock (_mutex) 4: { 5: _dictionary[key] = val; 6: } 7: }; 8: var getDelegate = (key) => 9: { 10: lock (_mutex) 11: { 12: string val; 13: return _dictionary.TryGetValue(key, out val) ? val : null; 14: } 15: }; Nothing new or fancy here, just your basic lock on a private object and then query/insert into the Dictionary. Now, for the Dictionary with ReadWriteLockSlim it's a little more complex: 1: var addDelegate = (key,val) => 2: { 3: _readerWriterLock.EnterWriteLock(); 4: _dictionary[key] = val; 5: _readerWriterLock.ExitWriteLock(); 6: }; 7: var getDelegate = (key) => 8: { 9: string val; 10: _readerWriterLock.EnterReadLock(); 11: if(!_dictionary.TryGetValue(key, out val)) 12: { 13: val = null; 14: } 15: _readerWriterLock.ExitReadLock(); 16: return val; 17: }; And finally, the ConcurrentDictionary, which since it does all it's own concurrency control, is remarkably elegant and simple: 1: var addDelegate = (key,val) => 2: { 3: _concurrentDictionary[key] = val; 4: }; 5: var getDelegate = (key) => 6: { 7: string s; 8: return _concurrentDictionary.TryGetValue(key, out s) ? s : null; 9: };                    Then, I set up a test harness that would simply ask the user for the number of concurrent Accessors to attempt to Access the cache (as specified in Accessor.Access() above) and then let them fly and see how long it took them all to complete.  Each of these tests was run with 10,000,000 cache accesses divided among the available Accessor instances.  All times are in milliseconds. 1: Dictionary with Mutex Locking 2: --------------------------------------------------- 3: Accessors Mostly Misses Mostly Hits 4: 1 7916 3285 5: 10 8293 3481 6: 100 8799 3532 7: 1000 8815 3584 8:  9:  10: Dictionary with ReaderWriterLockSlim Locking 11: --------------------------------------------------- 12: Accessors Mostly Misses Mostly Hits 13: 1 8445 3624 14: 10 11002 4119 15: 100 11076 3992 16: 1000 14794 4861 17:  18:  19: Concurrent Dictionary 20: --------------------------------------------------- 21: Accessors Mostly Misses Mostly Hits 22: 1 17443 3726 23: 10 14181 1897 24: 100 15141 1994 25: 1000 17209 2128 The first test I did across the board is the Mostly Misses category.  The mostly misses (more adds because data requested was not in the dictionary) shows an interesting trend.  In both cases the Dictionary with the simple mutex lock is much faster, and the ConcurrentDictionary is the slowest solution.  But this got me thinking, and a little research seemed to confirm it, maybe the ConcurrentDictionary is more optimized to concurrent "gets" than "adds".  So since the ratio of misses to hits were 2 to 1, I decided to reverse that and see the results. So I tweaked the data so that the number of keys were much smaller than the number of iterations to give me about a 2 to 1 ration of hits to misses (twice as likely to already find the item in the cache than to need to add it).  And yes, indeed here we see that the ConcurrentDictionary is indeed faster than the standard Dictionary here.  I have a strong feeling that as the ration of hits-to-misses gets higher and higher these number gets even better as well.  This makes sense since the ConcurrentDictionary is read-optimized. Also note that I tried the tests with capacity and concurrency hints on the ConcurrentDictionary but saw very little improvement, I think this is largely because on the 10,000,000 hit test it quickly ramped up to the correct capacity and concurrency and thus the impact was limited to the first few milliseconds of the run. So what does this tell us?  Well, as in all things, ConcurrentDictionary is not a panacea.  It won't solve all your woes and it shouldn't be the only Dictionary you ever use.  So when should we use each? Use System.Collections.Generic.Dictionary when: You need a single-threaded Dictionary (no locking needed). You need a multi-threaded Dictionary that is loaded only once at creation and never modified (no locking needed). You need a multi-threaded Dictionary to store items where writes are far more prevalent than reads (locking needed). And use System.Collections.Concurrent.ConcurrentDictionary when: You need a multi-threaded Dictionary where the writes are far more prevalent than reads. You need to be able to iterate over the collection without locking it even if its being modified. Both Dictionaries have their strong suits, I have a feeling this is just one where you need to know from design what you hope to use it for and make your decision based on that criteria.

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  • Loading data from a dictionary of dictionaries into an array in Objective C for an iphone app

    - by Kat
    I have a UINavigationController consisting of a tableview I want to load some data into. I have a dictionary plist containing Dictionaries for each Train Line which in turn have dictionaries for each station with the relevant information along with one string lineName. I need to collect the station Names keys and add them to an array to populate my table (This is working). The line names are stored as a string in my lines dictionary with the key being "lineName" Root->| | |->TrainLine1(Dictionary)->| | |-> lineName (String) | |-> Station1 (Dictionary) | |-> Station2 (Dictionary) | | |->TrainLine2(Dictionary)->| | |-> lineName (String) | |-> Station1 (Dictionary) | |-> Station2 (Dictionary) Am I going about this the wrong way? Should I reorganise my plist? The code below crashes the app. - (void)viewDidLoad { self.title = @"Train Lines"; NSString *path = [[NSBundle mainBundle] pathForResource:@"lineDetails" ofType:@"plist"]; NSDictionary *dictionary = [[NSDictionary alloc] initWithContentsOfFile:path]; NSMutableArray *array = [[NSMutableArray alloc] init]; NSMutableArray *lineNameArray = [[NSMutableArray alloc] init]; NSString *key; for (key in dictionary) { NSMutableDictionary *secondDictionary = [NSDictionary dictionaryWithDictionary:[dictionary valueForKey:key]]; [lineNameArray addObject:key]; NSLog(@"Adding this in array:%@", key); [array addObject:[secondDictionary objectForKey:kLineNameKey]]; } self.trainLines = array; self.trainLineKeys = lineNameArray; NSLog(@"Array contents:%@", self.trainLineKeys); [lineNameArray release]; [array release]; [dictionary release]; [super viewDidLoad]; }

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  • Remove English - United States language from Firefox

    - by Paul
    How do I remove the English (United States) dictionary from Firefox? It's not an add-on so I'm guessing it's built into Firefox by default. Maybe that makes it unremovable? I noticed whilst typing a Hotmail email in Firefox that the default language seems to be English/United States. As I am from the UK I thought I would add in the English/United Kingdom dictionary, which I have. This is now the default language and I don't need the US dictionary. Firefox 3.6.2 on Windows 7 Home Premium 32 bit.

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  • Take all fields in a database table and put them straight into a text file

    - by DalexL
    I have an database file (mdb) file that contains a dictionary of words. A couple thousand of them. I just need the words (in the order they are already in) put into a text file. Currently they have ID's associated with them (e.g. 1, 2, 3) but I don't need it. I just need the words. What is the best way to do this? Actually, if somebody is able to find a dictionary of English words (something along the lines of a scrabble dictionary) that is free online, I'll accept that too. I just can't seem to find any good ones online.

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  • null pointers vs. Null Object Pattern

    - by GlenH7
    Attribution: This grew out of a related P.SE question My background is in C / C++, but I have worked a fair amount in Java and am currently coding C#. Because of my C background, checking passed and returned pointers is second-hand, but I acknowledge it biases my point of view. I recently saw mention of the Null Object Pattern where the idea is than an object is always returned. Normal case returns the expected, populated object and the error case returns empty object instead of a null pointer. The premise being that the calling function will always have some sort of object to access and therefore avoid null access memory violations. So what are the pros / cons of a null check versus using the Null Object Pattern? I can see cleaner calling code with the NOP, but I can also see where it would create hidden failures that don't otherwise get raised. I would rather have my application fail hard (aka an exception) while I'm developing it than have a silent mistake escape into the wild. Can't the Null Object Pattern have similar problems as not performing a null check? Many of the objects I have worked with hold objects or containers of their own. It seems like I would have to have a special case to guarantee all of the main object's containers had empty objects of their own. Seems like this could get ugly with multiple layers of nesting.

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  • What should the name of this class be?

    - by Tim Murphy
    Naming classes is sometimes hard. What do you think name of the class should be? I originally created the class to use as a cache but can see its may have other uses. Example code to use the class. Dim cache = New NamePendingDictionary(Of String, Sample) Dim value = cache("a", Function() New Sample()) And here is the class that needs a name. ''' <summary> ''' Enhancement of <see cref="System.Collections.Generic.Dictionary"/>. See the Item property ''' for more details. ''' </summary> ''' <typeparam name="TKey">The type of the keys in the dictionary.</typeparam> ''' <typeparam name="TValue">The type of the values in the dictionary.</typeparam> Public Class NamePendingDictionary(Of TKey, TValue) Inherits Dictionary(Of TKey, TValue) Delegate Function DefaultValue() As TValue ''' <summary> ''' Gets or sets the value associated with the specified key. If the specified key does not exist ''' then <paramref name="createDefaultValue"/> is invoked and added to the dictionary. The created ''' value is then returned. ''' </summary> ''' <param name="key">The key of the value to get.</param> ''' <param name="createDefaultValue"> ''' The delegate to invoke if <paramref name="key"/> does not exist in the dictionary. ''' </param> ''' <exception cref="T:System.ArgumentNullException"><paramref name="key" /> is null.</exception> Default Public Overloads ReadOnly Property Item(ByVal key As TKey, ByVal createDefaultValue As DefaultValue) As TValue Get Dim value As TValue If createDefaultValue Is Nothing Then Throw New ArgumentNullException("createValue") End If If Not Me.TryGetValue(key, value) Then value = createDefaultValue.Invoke() Me.Add(key, value) End If Return value End Get End Property End Class

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  • What is the use of Association, Aggregation and Composition (Encapsulation) in Classes

    - by SahilMahajanMj
    I have gone through lots of theories about what is encapsulation and the three techniques of implementing it, which are Association, Aggregation and Composition. What i found is, Encapsulation Encapsulation is the technique of making the fields in a class private and providing access to the fields via public methods. If a field is declared private, it cannot be accessed by anyone outside the class, thereby hiding the fields within the class. For this reason, encapsulation is also referred to as data hiding. Encapsulation can be described as a protective barrier that prevents the code and data being randomly accessed by other code defined outside the class. Access to the data and code is tightly controlled by an interface. The main benefit of encapsulation is the ability to modify our implemented code without breaking the code of others who use our code. With this feature Encapsulation gives maintainability, flexibility and extensibility to our code. Association Association is a relationship where all object have their own lifecycle and there is no owner. Let’s take an example of Teacher and Student. Multiple students can associate with single teacher and single student can associate with multiple teachers but there is no ownership between the objects and both have their own lifecycle. Both can create and delete independently. Aggregation Aggregation is a specialize form of Association where all object have their own lifecycle but there is ownership and child object can not belongs to another parent object. Let’s take an example of Department and teacher. A single teacher can not belongs to multiple departments, but if we delete the department teacher object will not destroy. We can think about “has-a” relationship. Composition Composition is again specialize form of Aggregation and we can call this as a “death” relationship. It is a strong type of Aggregation. Child object dose not have their lifecycle and if parent object deletes all child object will also be deleted. Let’s take again an example of relationship between House and rooms. House can contain multiple rooms there is no independent life of room and any room can not belongs to two different house if we delete the house room will automatically delete. The question is: Now these all are real world examples. I am looking for some description about how to use these techniques in actual class code. I mean what is the point for using three different techniques for encapsulation, How these techniques could be implemented and How to choose which technique is applicable at time.

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  • Validation and Error Generation when using the Data Mapper Pattern

    - by AndyPerlitch
    I am working on saving state of an object to a database using the data mapper pattern, but I am looking for suggestions/guidance on the validation and error message generation step (step 4 below). Here are the general steps as I see them for doing this: (1) The data mapper is used to get current info (assoc array) about the object in db: +=====================================================+ | person_id | name | favorite_color | age | +=====================================================+ | 1 | Andy | Green | 24 | +-----------------------------------------------------+ mapper returns associative array, eg. Person_Mapper::getPersonById($id) : $person_row = array( 'person_id' => 1, 'name' => 'Andy', 'favorite_color' => 'Green', 'age' => '24', ); (2) the Person object constructor takes this array as an argument, populating its fields. class Person { protected $person_id; protected $name; protected $favorite_color; protected $age; function __construct(array $person_row) { $this->person_id = $person_row['person_id']; $this->name = $person_row['name']; $this->favorite_color = $person_row['favorite_color']; $this->age = $person_row['age']; } // getters and setters... public function toArray() { return array( 'person_id' => $this->person_id, 'name' => $this->name, 'favorite_color' => $this->favorite_color, 'age' => $this->age, ); } } (3a) (GET request) Inputs of an HTML form that is used to change info about the person is populated using Person::getters <form> <input type="text" name="name" value="<?=$person->getName()?>" /> <input type="text" name="favorite_color" value="<?=$person->getFavColor()?>" /> <input type="text" name="age" value="<?=$person->getAge()?>" /> </form> (3b) (POST request) Person object is altered with the POST data using Person::setters $person->setName($_POST['name']); $person->setFavColor($_POST['favorite_color']); $person->setAge($_POST['age']); *(4) Validation and error message generation on a per-field basis - Should this take place in the person object or the person mapper object? - Should data be validated BEFORE being placed into fields of the person object? (5) Data mapper saves the person object (updates row in the database): $person_mapper->savePerson($person); // the savePerson method uses $person->toArray() // to get data in a more digestible format for the // db gateway used by person_mapper Any guidance, suggestions, criticism, or name-calling would be greatly appreciated.

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  • Object Oriented Design Questions

    - by Robert
    Hello there. I am going to develop a Tic-Tac-Toe game using Java(or maybe other OO Languages).Now I have a picture in my mind about the general design. Interface: Player ,then I will be able to implement a couple of Player classes,based on how I want the opponent to be,for example,random player,intelligent player. Classes: Board class,with a two-dimensional array of integers,0 indicates open,1 indicates me,-1 indicates opponent.The evaluation function will be in here as well,to return the next best move based on the current board arrangement and whose turn it is. Refree class,which will create instance of the Board and two player instances,then get the game begin. This is a rough idea of my OO design,could anybody give me any critiques please,I find this is really beneficial,thank you very much.

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  • Object.Watch with disabled attribute

    - by Benjamin Fleming
    <html> <head> <script type="text/javascript"> window.onload = function() { var btn = document.getElementById("button"); var tog = document.getElementById("toggle"); tog.onclick = function() { if(btn.disabled) { btn.disabled = false; } else { btn.disabled = true; } }; //btn.watch("disabled", function(prop, val, newval) { }); }; </script> </head> <body> <input type="button" value="Button" id="button" /> <input type="button" value="Toggle" id="toggle" /> </body> </html> If you test this code, the Toggle button will successfully enable and disable the other button. However, un-commenting the btn.watch() line will somehow always set the disabled tag to true. Any ideas?

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  • Class Design - Returning a List<Object> From <Object>

    - by Mike
    Given a simple class: public class Person { public string FirstName; public string LastName; public string GetFullName() { return FirstName + LastName; } } The user of this class will populate a List<Person> object by reading an Xml file or some other data source. Should the logic for populating the List be in the Person class or should it just remain in the calling class? In other words, should there be a public List<Persons> GetPersons() method in the Person class or in the calling class? Or should the data accessor be in another class altogether? I know this is a rather simplistic question but I'm just curious how others typically do it.

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