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• Beyond core java

  - by Paul

  Coming to the end of the first year of my CS degree, we've done some Java but just the core stuff; manipulating strings and arrays, inheritance, implementing logic etc. I visit this website daily and I see so much stuff that is beyond me; using frameworks; managing databases etc. It makes me feel like I've just learned the syntax of Java, and there is so much more to do with it. My question is though, how do I get there? I don't think I'm advanced enough to join an open source project, which seems to be suggested often (though I'd love to) and I've looked at other similar questions on here (like this one) but even then I don't think that'd work for me.. firstly, could somebody try give me some commonly used frameworks etc and how and what they are used for? Where would be a good place to start? How did you get started in using the things you do? Or perhaps you think I'm going down the wrong route. Should I learn another language, and just wait until the moment occurs where it's clear what I should be doing? I'm only in the first year of my degree, so far we've lightly covered Haskell and Java, and I've done a little HTML and CSS in my free time. I know that next year we cover python, so perhaps I should just wait till then and see if I prefer that? I feel like I also risk learning something in depth and then never using it... I suppose I'm also asking for personal experiences; was there a point where you felt you'd exceeded the basic grasp of a language (does not necessarily have to be Java related) and reach a more "advanced" level? I guess I'll put subjective tag on this, but really I just want to know how to get beyond the basic understanding of a language.

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• How do I assert that two arbitrary type objects are equivalent, without requiring them to be equal?

  - by Tomas Lycken

  To accomplish this (but failing to do so) I'm reflecting over properties of an expected and actual object and making sure their values are equal. This works as expected as long as their properties are single objects, i.e. not lists, arrays, IEnumerable... If the property is a list of some sort, the test fails (on the Assert.AreEqual(...) inside the for loop). public void WithCorrectModel<TModelType>(TModelType expected, string error = "") where TModelType : class { var actual = _result.ViewData.Model as TModelType; Assert.IsNotNull(actual, error); Assert.IsInstanceOfType(actual, typeof(TModelType), error); foreach (var prop in typeof(TModelType).GetProperties()) { Assert.AreEqual(prop.GetValue(expected, null), prop.GetValue(actual, null), error); } } If dealing with a list property, I would get the expected results if I instead used CollectionAssert.AreEquivalent(...) but that requires me to cast to ICollection, which in turn requries me to know the type listed, which I don't (want to). It also requires me to know which properties are list types, which I don't know how to. So, how should I assert that two objects of an arbitrary type are equivalent? Note: I specifically don't want to require them to be equal, since one comes from my tested object and one is built in my test class to have something to compare with.

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• Copy a multi-dimentional array by Value (not by reference) in PHP.

  - by Simon R

  Language: PHP I have a form which asks users for their educational details, course details and technical details. When the form is submitted the page goes to a different page to run processes on the information and save parts to a database. HOWEVER(!) I then need to return the page back to the original page, where having access to the original post information is needed. I thought it would be simple to copy (by value) the multi-dimensional (md) $_POST array to $_SESSION['post'] session_start(); $_SESSION['post'] = $_POST; However this only appears to place the top level of the array into $_SESSION['post'] not doing anything with the children/sub-arrays. An abbreviated form of the md $_POST array is as follows: Array ( [formid] = 2 [edu] = Array ( ['id'] = Array ( [1] = new_1 [2] = new_2 ) ['nameOfInstitution'] = Array ( [1] = 1 [2] = 2 ) ['qualification'] = Array ( [1] = blah [2] = blah ) ['grade'] = Array ( [1] = blah [2] = blah ) ) [vID] = 61 [Submit] = Save and Continue ) If I echo $_SESSION['post']['formid'] it writes "2", and if I echo $_SESSION['post']['edu'] it returns "Array". If I check that edu is an array (is_array($_SESSION['post']['edu])) it returns true. If I echo $_SESSION['post']['edu']['id'] it returns array, but when checked (is_array($_SESSION['post']['edu]['id'])) it returns false and I cannot echo out any of the elements. How do I successfully copy (by value, not by reference) the whole array (including its children) to an new array?

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• Calling handwritten CUDA kernel with thrust

  - by macs

  Hi, since i needed to sort large arrays of numbers with CUDA, i came along with using thrust. So far, so good...but what when i want to call a "handwritten" kernel, having a thrust::host_vector containing the data? My approach was (backcopy is missing): int CUDA_CountAndAdd_Kernel(thrust::host_vector<float> *samples, thrust::host_vector<int> *counts, int n) { thrust::device_ptr<float> dSamples = thrust::device_malloc<float>(n); thrust::copy(samples->begin(), samples->end(), dSamples); thrust::device_ptr<int> dCounts = thrust::device_malloc<int>(n); thrust::copy(counts->begin(), counts->end(), dCounts); float *dSamples_raw = thrust::raw_pointer_cast(dSamples); int *dCounts_raw = thrust::raw_pointer_cast(dCounts); CUDA_CountAndAdd_Kernel<<<1, n>>>(dSamples_raw, dCounts_raw); thrust::device_free(dCounts); thrust::device_free(dSamples); } The kernel looks like: __global__ void CUDA_CountAndAdd_Kernel_Device(float *samples, int *counts) But compilation fails with: error: argument of type "float **" is incompatible with parameter of type "thrust::host_vector *" Huh?! I thought i was giving float and int raw-pointers? Or am i missing something?

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• c# : How ot create a grid row array programatically

  - by user234839

  I am working in c# and i am under a situation where i have a grid (childGrid) and inside this grid i want to create 3 more grids dynamically. I want to achieve it using arrays. My try to do this is: Grid[] row = new Grid[counts]; for (int i = 0; i < counts; i++) { row[i].RowDefinitions[counts].Add(new RowDefinition()); } for (int i = 0; i < counts; i++) { Grid.SetColumn(txtblkLabel, 0); Grid.SetRow(row[i], 0); row[i].Children.Add(txtblkLabel); Grid.SetColumn(sp, 1); Grid.SetRow(row[i], 0); row[i].Children.Add(sp); Grid.SetColumn(txtblkShowStatus, 2); Grid.SetRow(row[i], 0); row[i].Children.Add(txtblkShowStatus); childGrid.Children.Add(row[i]); } the line row[i].RowDefinitions[counts].Add(new RowDefinition()); gives error. Error 1'System.Windows.Controls.RowDefinition' does not contain a definition for 'Add' and no extension method 'Add' accepting a first argument of type 'System.Windows.Controls.RowDefinition' could be found (are you missing a using directive or an assembly reference?) How to achieve this ?

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• c incompatible types in assignment, problem with pointers?

  - by Fantastic Fourier

  Hi I'm working with C and I have a question about assigning pointers. struct foo { int _bar; char * _car[MAXINT]; // this is meant to be an array of char * so that it can hold pointers to names of cars } int foofunc (void * arg) { int bar; char * car[MAXINT]; struct foo thing = (struct foo *) arg; bar = arg->_bar; // this works fine car = arg->_car; // this gives compiler errors of incompatible types in assignment } car and _car have same declaration so why am I getting an error about incompatible types? My guess is that it has something to do with them being pointers (because they are pointers to arrays of char *, right?) but I don't see why that is a problem. when i declared char * car; instead of char * car[MAXINT]; it compiles fine. but I don't see how that would be useful to me later when I need to access certain info using index, it would be very annoying to access that info later. in fact, I'm not even sure if I am going about the right way, maybe there is a better way to store a bunch of strings instead of using array of char *?

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• define keys in multidimensional array from csv

  - by mourique

  I want to compare two arrays, one coming from a shoppingcart and the other one parsed from a csv-file. The array from the shopping cart looks like this: Array ( [0] => Array ( [id] => 7 [qty] => 1 [price] => 07.39 [name] => walkthebridge [subtotal] => 7.39 ) [1] => Array ( [id] => 2 [qty] => 1 [price] => 07.39 [name] => milkyway [subtotal] => 7.39 ) ) The array from my csv-file however looks like this Array ( [0] => Array ( [0] => 1 [1] => walkthebridge [2] => 07.39 ) [1] => Array ( [0] => 2 [1] => milkyway [2] => 07.39 ) ) and is build using this code $checkitems = array(); $file = fopen('checkitems.csv', 'r'); while (($result = fgetcsv($file)) !== false) { $checkitems[] = $result; } fclose($file); how can i get the keys in the second array to match those in the first one? ( So that 0 would be id, and 1 would be name and so on) thanks in advance

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• Do I really need bindParam?

  - by sandelius

  Hi there! I'm trying to do a little PDO CRUD to learn some PDO. I have a question about bindParam. Here's my update method right now: public static function update($conditions = array(), $data = array(), $table = '') { self::instance(); // Late static bindings (PHP 5.3) $table = ($table === '') ? self::table() : $table; // Check which data array we want to use $values = (empty($data)) ? self::$_fields : $data; $sql = "UPDATE $table SET "; foreach ($values as $f => $v) { $sql .= "$f = ?, "; } // let's build the conditions self::build_conditions($conditions); // fix our WHERE, AND, OR, LIKE conditions $extra = self::$condition_string; // querystring $sql = rtrim($sql, ', ') . $extra; // let's merge the arrays into on $v_val = array_values($values); $c_val = array_values($conditions); $array = array_merge($v_val, self::$condition_array); $stmt = self::$db->prepare($sql); return $stmt->execute($array); } in my "self::$condition_array" I get all the right values from the ?. SO the query looks like this: UPDATE table SET this = ?, another = ? WHERE title = ? AND time = ? as you can see I dont use bindParams instead I pass the right values in the right order ($array) directly into the execute($array) method. This works like a charm BUT is it safe not use use bindParam here? If not then how can I do it? Thanks from Sweden Tobias

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• StructureMap and injecting IEnumerable<T>

  - by GiddyUpHorsey

  I'm new to StructureMap and have some existing code that I'm working with that uses StructureMap 2.5.4. There is a class that is constructed using StructureMap that has a constructor that takes IEnumerable<TCar> as a parameter. The registry has the following code. Scan(x => { x.TheCallingAssembly(); x.WithDefaultConventions(); x.AddAllTypesOf<ICar>(); } ); ForRequestedType<IEnumerable<ICar>>().TheDefault.Is.ConstructedBy( x => ObjectFactory.GetAllInstances<ICar>()); I'm writing a unit test and have obtained a nested container off the ObjectFactory and have injected an instance using the Inject method. One of the instances of ICar should receive the injected type in its constructor. However it wasn't working and I tracked that down to the ObjectFactory.GetAllInstances() call which doesn't use my nested container. How can I get this to work? I also read about StructureMap autowiring arrays and IEnumerable instances but I couldn't get it to work. Is there a better way to rewrite the above registry code so that an instance of IEnumerable<TCar> will be created and use the injected type from my nested container?

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• Using recursion to to trim a binary tree based on a given min and max value

  - by Justin

  As the title says, I have to trim a binary tree based on a given min and max value. Each node stores a value, and a left/right node. I may define private helper methods to solve this problem, but otherwise I may not call any other methods of the class nor create any data structures such as arrays, lists, etc. An example would look like this: overallRoot _____[50]____________________ / \ __________[38] _______________[90] / \ / _[14] [42] [54]_____ / \ \ [8] [20] [72] \ / \ [26] [61] [83] trim(52, 65); should return: overallRoot [54] \ [61] My attempted solution has three methods: public void trim(int min, int max) { rootFinder(overallRoot, min, max); } First recursive method finds the new root perfectly. private void rootFinder(IntTreeNode node, int min, int max) { if (node == null) return; if (overallRoot.data < min) { node = overallRoot = node.right; rootFinder(node, min, max); } else if (overallRoot.data > max) { node = overallRoot = node.left; rootFinder(node, min, max); } else cutter(overallRoot, min, max); } This second method should eliminate any further nodes not within the min/max, but it doesn't work as I would hope. private void cutter(IntTreeNode node, int min, int max) { if (node == null) return; if (node.data <= min) { node.left = null; } if (node.data >= max) { node.right = null; } if (node.data < min) { node = node.right; } if (node.data > max) { node = node.left; } cutter(node.left, min, max); cutter(node.right, min, max); } This returns: overallRoot [54]_____ \ [72] / [61] Any help is appreciated. Feel free to ask for further explanation as needed.

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• What is the most efficient/elegant way to parse a flat table into a tree?

  - by Tomalak

  Assume you have a flat table that stores an ordered tree hierarchy: Id Name ParentId Order 1 'Node 1' 0 10 2 'Node 1.1' 1 10 3 'Node 2' 0 20 4 'Node 1.1.1' 2 10 5 'Node 2.1' 3 10 6 'Node 1.2' 1 20 What minimalistic approach would you use to output that to HTML (or text, for that matter) as a correctly ordered, correctly intended tree? Assume further you only have basic data structures (arrays and hashmaps), no fancy objects with parent/children references, no ORM, no framework, just your two hands. The table is represented as a result set, which can be accessed randomly. Pseudo code or plain English is okay, this is purely a conceptional question. Bonus question: Is there a fundamentally better way to store a tree structure like this in a RDBMS? EDITS AND ADDITIONS To answer one commenter's (Mark Bessey's) question: A root node is not necessary, because it is never going to be displayed anyway. ParentId = 0 is the convention to express "these are top level". The Order column defines how nodes with the same parent are going to be sorted. The "result set" I spoke of can be pictured as an array of hashmaps (to stay in that terminology). For my example was meant to be already there. Some answers go the extra mile and construct it first, but thats okay. The tree can be arbitrarily deep. Each node can have N children. I did not exactly have a "millions of entries" tree in mind, though. Don't mistake my choice of node naming ('Node 1.1.1') for something to rely on. The nodes could equally well be called 'Frank' or 'Bob', no naming structure is implied, this was merely to make it readable. I have posted my own solution so you guys can pull it to pieces.

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• How to manipulate *huge* amounts of data

  - by Alejandro

  Hi there! I'm having the following problem. I need to store huge amounts of information (~32 GB) and be able to manipulate it as fast as possible. I'm wondering what's the best way to do it (combinations of programming language + OS + whatever you think its important). The structure of the information I'm using is a 4D array (NxNxNxN) of double-precission floats (8 bytes). Right now my solution is to slice the 4D array into 2D arrays and store them in separate files in the HDD of my computer. This is really slow and the manipulation of the data is unbearable, so this is no solution at all! I'm thinking on moving into a Supercomputing facility in my country and store all the information in the RAM, but I'm not sure how to implement an application to take advantage of it (I'm not a professional programmer, so any book/reference will help me a lot). An alternative solution I'm thinking on is to buy a dedicated server with lots of RAM, but I don't know for sure if that will solve the problem. So right now my ignorance doesn't let me choose the best way to proceed. What would you do if you were in this situation? I'm open to any idea. Thanks in advance!

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• Designing a general database interface in PHP

  - by lamas

  I'm creating a small framework for my web projects in PHP so I don't have to do the basic work over and over again for every new website. It is not my goal to create a second CakePHP or Codeigniter and I'm also not planning to build my websites with any of the available frameworks as I prefer to use things I've created myself in general. I have no problems in designing that framework when it comes to parts like the core structure, request handling, and so on but I'm getting stuck with designing the database interface for my modules. I've already thought about using the MVC pattern but thought that it would be a bit of a overkill. So the exact problem I'm facing is how my frameworks modules (viewCustomers could be a module, for example) should interact with the database. Is it a good idea to write SQL directly in PHP (mysql_query( 'SELECT firstname, lastname(.....))? How could I abstract a query like SELECT firstname, lastname FROM customers WHERE id=X Would MySQL helper functions like $this->db->get( array('firstname', 'lastname'), array('id'=>X) ) be a good idea? I suppose not because they actually make everything more complicated by requiring arrays to be created and passed. Is the Model pattern from MVC my only real option?

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• Searching a column containing CSV data in a MySQL table for existence of input values

  - by Adarsh R

  Hi, I have a table say, ITEM, in MySQL that stores data as follows: ID FEATURES -------------------- 1 AB,CD,EF,XY 2 PQ,AC,A3,B3 3 AB,CDE 4 AB1,BC3 -------------------- As an input, I will get a CSV string, something like "AB,PQ". I want to get the records that contain AB or PQ. I realized that we've to write a MySQL function to achieve this. So, if we have this magical function MATCH_ANY defined in MySQL that does this, I would then simply execute an SQL as follows: select * from ITEM where MATCH_ANY(FEAURES, "AB,PQ") = 0 The above query would return the records 1, 2 and 3. But I'm running into all sorts of problems while implementing this function as I realized that MySQL doesn't support arrays and there's no simple way to split strings based on a delimiter. Remodeling the table is the last option for me as it involves lot of issues. I might also want to execute queries containing multiple MATCH_ANY functions such as: select * from ITEM where MATCH_ANY(FEATURES, "AB,PQ") = 0 and MATCH_ANY(FEATURES, "CDE") In the above case, we would get an intersection of records (1, 2, 3) and (3) which would be just 3. Any help is deeply appreciated. Thanks

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• How to play extracted wave file byte array in C#?

  - by user261924

  At the moment i have managed to separate the left and right channel of a WAVE file and have included the header in a byte[] array. My next step is to be about to play both channels. How can this be done? Here is a code snippet: byte[] song_left = new byte[fa.Length]; byte[] song_right = new byte[fa.Length]; int p = 0; for (int c = 0; c < 43; c++) { song_left[p] = header[c]; p++; } int q = 0; for (s = startByte; s < length; s = s + 3) { song_left[s] = sLeft[q]; q++; s++; song_left[s] = sLeft[q]; q++; } p = 0; for (int c = 0; c < 43; c++) { song_right[p] = header[c]; p++; } This part is reading the header and data from both the right and light channel and saving it to array sLeft[] and sRight[]. This part is working perfectly. Once I obtained the byte arrays, I did the following: System.IO.File.WriteAllBytes("c:\\left.wav", song_left); System.IO.File.WriteAllBytes("c:\\right.wav", song_right); Added a button to play the saved wave file: private void button2_Click(object sender, EventArgs e) { spWave = new SoundPlayer("c:\\left.wav"); spWave.Play(); } Once I hit the play button, this error appers: An unhandled exception of type 'System.InvalidOperationException' occurred in System.dll Additional information: The wave header is corrupt. Any ideas?

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• substitution cypher with different alphabet length

  - by seanizer

  I would like to implement a simple substitution cypher to mask private ids in URLs I know how my IDs will look like (combination of upperchase ascii, digits and underscore), and they will be rather long, as they are composed keys. I would like to use a longer alphabet to shorten the resulting codes (I'd like to use upper and lower case ascii letters, digits and nothing else). So my incoming alphabet would be [A-Z0-9_] (37 chars) and my outgoing alphabet would be [A-Za-z0-9] (62 chars) so a compression of almost 50% would be available. let's say my URLs look like this: /my/page/GFZHFFFZFZTFZTF_24_F34 and I want them to look like this instead: /my/page/Ft32zfegZFV5 Obviously both arrays would be shuffled to bring some random order in. This does not have to be secure. if someone figures it out: fine, but I don't want the scheme to be obvious. My desired solution would be to convert the string to an integer representation of radix 37, convert the radix to 62 and use the second alphabet to write out that number. is there any sample code available that does something similar? Integer.parseInt ( http://java.sun.com/javase/6/docs/api/java/lang/Integer.html#parseInt%28java.lang.String,%20int%29 ) has some similar logic, but it is hard-coded to use standard digit behavior Any hints? I am using java to implement this but code or pseudo-code in any other language is of course also helpful

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• Draw a position from a 2d Array on respected canvas location

  - by Anon

  Background: I have two 2d arrays. Each index within each 2d array represents a tile which is drawn on a square canvas suitable for 8 x 8 tiles. The first 2d array represents the ground tiles and is looped and drawn on the canvas using the following code: //Draw the map from the land 2d array map = new Canvas(mainFrame, 20, 260, 281, 281); for(int i=0; i < world.length; i++){ for(int j=0; j < world[i].length; j++){ for(int x=0; x < 280; x=x+35){ for(int y=0; y < 280; y=y+35){ Point p = new Point(x,y); map.add(new RectangleObject(p,35,35,Colour.green)); } } } } This creates a grid of green tiles 8 x 8 across as intended. The second 2d array represents the position on the ground. This 2d array has everyone of its indexes as null apart from one which is comprised of a Person class. Problem I am unsure of how I can draw the position on the grid. I was thinking of a similar loop, so it draws over the previous 2d array another set of 64 tiles. Only this time they are all transparent but the one tile which isn't null. In other words, the tile where Person is located. I wanted to use a search throughout the loop using a comparative if statement along the lines of if(!(world[] == null)){ map.add(new RectangleObject(p,35,35,Colour.red));} However my knowledge is limited and I am confused on how to implement it.

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• Mysqli connection trying with different users

  - by gerardo

  I'm trying to create a PHP class extending mysqli that is capable of connecting with another user if the connection fails. It is probably easier to explain with code: public function __construct() { $users = new ArrayObject(self::$user); $passwords = new ArrayObject(self::$pass); $itUser = $users->getIterator(); $itPass = $passwords->getIterator(); parent::__construct(self::$host, $itUser->current(), $itPass->current(), self::$prefix.self::$db); while($this->connect_errno && $itUser->valid()){ $itUser->next(); $itPass->next(); $this->change_user($itUser->current(), $itPass->current(), self::$prefix.self::$db); } if($this->connect_errno) throw new Exception("Error", $this->connect_errno); } $user and $pass are static variables containing arrays of users and passwords. If the first user fails to connect, I try with the next one. The problem here is with $this->connect_errno. It says it cannot find Mysqli. Is there any solution to this or should I create a Factory class?

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• Is my objective possible using WCF (and is it the right way to do things?)

  - by David

  I'm writing some software that modifies a Windows Server's configuration (things like MS-DNS, IIS, parts of the filesystem). My design has a server process that builds an in-memory object graph of the server configuration state and a client which requests this object graph. The server would then serialize the graph, send it to the client (presumably using WCF), the server then makes changes to this graph and sends it back to the server. The server receives the graph and proceeds to make modifications to the server. However I've learned that object-graph serialisation in WCF isn't as simple as I first thought. My objects have a hierarchy and many have parametrised-constructors and immutable properties/fields. There are also numerous collections, arrays, and dictionaries. My understanding of WCF serialisation is that it requires use of either the XmlSerializer or DataContractSerializer, but DCS places restrictions on the design of my object-graph (immutable data seems right-out, it also requires parameter-less constructors). I understand XmlSerializer lets me use my own classes provided they implement ISerializable and have the de-serializer constructor. That is fine by me. I spoke to a friend of mine about this, and he advocates going for a Data Transport Object-only route, where I'd have to maintain a separate DataContract object-graph for the transport of data and re-implement my server objects on the client. Another friend of mine said that because my service only has two operations ("GetServerConfiguration" and "PutServerConfiguration") it might be worthwhile just skipping WCF entirely and implementing my own server that uses Sockets. So my questions are: Has anyone faced a similar problem before and if so, are there better approaches? Is it wise to send an entire object graph to the client for processing? Should I instead break it down so that the client requests a part of the object graph as it needs it and sends only bits that have changed (thus reducing concurrency-related risks?)? If sending the object-graph down is the right way, is WCF the right tool? And if WCF is right, what's the best way to get WCF to serialise my object graph?

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• Why does Microsoft advise against readonly fields with mutable values?

  - by Weeble

  In the Design Guidelines for Developing Class Libraries, Microsoft say: Do not assign instances of mutable types to read-only fields. The objects created using a mutable type can be modified after they are created. For example, arrays and most collections are mutable types while Int32, Uri, and String are immutable types. For fields that hold a mutable reference type, the read-only modifier prevents the field value from being overwritten but does not protect the mutable type from modification. This simply restates the behaviour of readonly without explaining why it's bad to use readonly. The implication appears to be that many people do not understand what "readonly" does and will wrongly expect readonly fields to be deeply immutable. In effect it advises using "readonly" as code documentation indicating deep immutability - despite the fact that the compiler has no way to enforce this - and disallows its use for its normal function: to ensure that the value of the field doesn't change after the object has been constructed. I feel uneasy with this recommendation to use "readonly" to indicate something other than its normal meaning understood by the compiler. I feel that it encourages people to misunderstand the meaning of "readonly", and furthermore to expect it to mean something that the author of the code might not intend. I feel that it precludes using it in places it could be useful - e.g. to show that some relationship between two mutable objects remains unchanged for the lifetime of one of those objects. The notion of assuming that readers do not understand the meaning of "readonly" also appears to be in contradiction to other advice from Microsoft, such as FxCop's "Do not initialize unnecessarily" rule, which assumes readers of your code to be experts in the language and should know that (for example) bool fields are automatically initialised to false, and stops you from providing the redundancy that shows "yes, this has been consciously set to false; I didn't just forget to initialize it". So, first and foremost, why do Microsoft advise against use of readonly for references to mutable types? I'd also be interested to know: Do you follow this Design Guideline in all your code? What do you expect when you see "readonly" in a piece of code you didn't write?

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• Hashtable with int array as key in java

  - by Niels Hansen

  Hey! I'm trying to make a hashtable in java where the keys are int[], but it dosen't work. I have made a little test program to show my problem: public class test{ public static void main(String[] args){ int[] test0 = {1,1}; int[] test1 = {1,1}; Hashtable<int[], String> ht = new Hashtable<int[], String>(); String s0 = "foo"; ht.put(test0, s0); System.out.println("the result from ht.get(test1)"); System.out.println(ht.get(test1)); System.out.println("the result from ht.get(test0)"); System.out.println(ht.get(test0)); } } My intention is that both ht.get calles should return the same result, since the two arrays are equal, but they dont. Here is the result from running the code: the result from ht.get(test1) null the result from ht.get(test0) foo Am I missing something here or is it just impossible to use int[] as keys in a hastable?

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• Design of std::ifstream class

  - by Nawaz

  Those of us who have seen the beauty of STL try to use it as much as possible, and also encourage others to use it wherever we see them using raw pointers and arrays. Scott Meyers have written a whole book on STL, with title Effective STL. Yet what happened to the developers of ifstream that they preferred char* over std::string. I wonder why the first parameter of ifstream::open() is of type const char*, instead of const std::string &. Please have a look at it's signature: void open(const char * filename, ios_base::openmode mode = ios_base::in ); Why this? Why not this: void open(const string & filename, ios_base::openmode mode = ios_base::in ); Is this a serious mistake with the design? Or this design is deliberate? What could be the reason? I don't see any reason why they have preferred char* over std::string. Note we could still pass char* to the latter function that takes std::string. That's not a problem! By the way, I'm aware that ifstream is a typedef, so no comment on my title.:P. It looks short that is why I used it. The actual class template is : template<class _Elem,class _Traits> class basic_ifstream;

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• Textures in Opengl ES 2 not working properly

  - by Adl

  Hi! I'm working with Opengl ES 2 on iphone and right now I am trying to get my textures working on my objects. I'm using .obj files and all the data in them are correct. I have written a parser myself to retrieve all data, I convert it to static arrays in C. I discard the material properties for now, only getting the image path from the .mtl files manually. I have an object with 336 triangles, making this non-trivial to observe, with appertaining vertices, vertex faces and texture coordinates (u,v). Passing all data into the shaders, the resulting image is this: http://img530.imageshack.us/img530/9637/pic1io.png http://img404.imageshack.us/img404/7358/pic2pg.png But it should look like this (Displaying it in an object viewer). Please ignore the material properties. http://img16.imageshack.us/img16/1401/pic3cq.png Using this image as a texture: http://img217.imageshack.us/img217/1300/shirtdiffuse.png I'm thinking it might have to do with texture coordinate faces ? It is defined in my .obj file, and I'm not using them at all. In books and tutorials I have not found anything concerning this. Regards Niclas

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• Using Array Controllers to restrict the view in one popup depending on the selection in another. Not

  - by mjohnh

  I am working on an app that is not core data based - the data feed is a series of web services. Two arrays are created from the data feed. The first holds season data, each array object being an NSDictionary. Two of the NSDictionary entries hold the data to be displayed in the popup ('seasonName') and an id ('seasonID') that acts as a pointer (in an external table) by matches defined for that season. The second array is also a collection of NSDictionaries. Two of the entries hold the data to be displayed in the popup ('matchDescription') and the id ('matchSeasonId') that points to the seasonId defined in the NSDictionaries in first array. I have two NSPopUps. I want the first to display the season names and the second to display the matches defined for that season, depending on the selection in the first. I'm new at bindings, so excuse me if I've missed something obvious. I've tried using ArrayControllers as follows: SeasonsArrayController: content bound to appDelegate seasonsPopUpArrayData. seasonsPopup: content bound to SeasonsArrayController.arrangedObjects; content value bound to SeasonsArrayController.arrangedObjects.seasonName I see the season names fine. I can obviously follow a similar route to see the matches, but I then see them all, instead of restricting the list to the matches for the season highlighted. All the tutorials I can find seem to revolve around core data and utilise the relationships defined therein. I don't have that luxury here. Any help very gratefully received.

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• Struts2 Converting Enum Array fills array with single null value

  - by Kyle Partridge

  For a simple action class with these member variables: ... private TestConverterEnum test; private TestConverterEnum[] tests; private List<TestConverterEnum> tList; ... And a simple enum: public enum TestConverterEnum { A, B, C; } Using the default struts2 enum conversion, when I send the request like so: TestConterter.action?test=&tests=&tList=&b=asdf For test I get a null value, which is expected. For the Array and List, however, I get and Array (or list) with one null element. Is this what is expected? Is there a way to prevent this. We recently upgraded our struts2 version, and we had our own converters, which also don't work in this case, so I was hoping to use the default conversion method. We already have code that is validating these arrays for null and length, and I don't want to have to add another condition to these branches. Is there a way to prevent this bevavior?

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