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• Port Monitor: How to receive the number of document copies during the printing

  In this article, we will examine a problem of receiving the correct value of the dmCopies variable in the DEVMODE structure while printing from Microsoft Word 2003.

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• Rule of thumb for enemy design

  - by Terrance

  I'm at the early stages of developing a 2d side scrolling open ended platformer (think metroidvania) and am having a bit of difficulty at enemy design inspiration for something of a scifi, nature, fantasy setting that isn't overly familar or obvious. I haven't seen too many articles blogs or books that talk about the subject at great length. Is there a fair rule of thumb when coming up with enemy design with respect to keeping your player engaged?

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• Game state management (Game, Menu, Titlescreen, etc)

  - by munchor

  Basically, in every single game I've made so far, I always have a variable like "current_state", which can be "game", "titlescreen", "gameoverscreen", etc. And then on my Update function I have a huge: if current_state == "game" game stuf ... else if current_state == "titlescreen" ... However, I don't feel like this is a professional/clean way of handling states. Any ideas on how to do this in a better way? Or is this the standard way?

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• Looping in Python and keeping current line after sub routine [migrated]

  - by Brendan

  I've been trying to nut out an issue when looping in python 3. When returning from sub routine the "line" variable has not incremented. How do I get the script to return the latest readline from the subsroutine? Code below def getData(line): #print(line) #while line in sTSDP_data: while "/service/content/test" not in line: line = sTSDP_data.readline() import os, sys sFileTSDP = "d:/ess/redo/Test.log" sTSDP_data = open(sFileTSDP, "r") for line in sTSDP_data: if "MOBITV" in line: getData(line) #call sub routine print(line)

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• Convert VARCHAR() columns to NVARCHAR()

  - by ChrisD

  We recently underwent an upgrade that required us to change our database columns from varchar to NVarchar, to support unicode characters. Digging through the internet, I found a base script which I modified to handle reserved word table names, and maintain the NULL/NotNull constraint of the columns.   I Ran this script use NWOperationalContent – Your Catalog Name here GO SELECT 'ALTER TABLE ' + isnull(schema_name(syo.id), 'dbo') + '.[' +  syo.name +'] '     + ' ALTER COLUMN [' + syc.name + '] NVARCHAR(' + case syc.length when -1 then 'MAX'         ELSE convert(nvarchar(10),syc.length) end + ') '+         case  syc.isnullable when 1 then ' NULL' ELSE ' NOT NULL' END +';'    FROM sysobjects syo    JOIN syscolumns syc ON      syc.id = syo.id    JOIN systypes syt ON      syt.xtype = syc.xtype    WHERE      syt.name = 'varchar'     and syo.xtype='U'   which produced a series of ALTER statements which I could then execute the tables.  In some cases I had to drop indexes, alter the tables, and re-create the indexes.  There might have been a better way to do that, but manually dropping them got the job done.   use NWMerchandisingContent GO ALTER TABLE Locale Drop Constraint PK_Locale ALTER TABLE Country DROP CONSTRAINT PK_Country GO ALTER TABLE dbo.[Campaign]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[BundleLocalization]  ALTER COLUMN [Locale] NVARCHAR(8)  NOT NULL; ALTER TABLE dbo.[BundleLocalization]  ALTER COLUMN [UnitOfmeasure] NVARCHAR(200)  NULL; ALTER TABLE dbo.[BundleLocalization]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[BundleComponentLocalization]  ALTER COLUMN [Locale] NVARCHAR(8)  NOT NULL; ALTER TABLE dbo.[BundleComponentLocalization]  ALTER COLUMN [Imperative] NVARCHAR(MAX)  NULL; ALTER TABLE dbo.[BundleComponentLocalization]  ALTER COLUMN [Instructions] NVARCHAR(MAX)  NULL; ALTER TABLE dbo.[BundleComponentLocalization]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[BundleComponent]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[Bundle]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[Banner]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[Video]  ALTER COLUMN [Link] NVARCHAR(512)  NOT NULL; ALTER TABLE dbo.[Video]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[ProductUsage]  ALTER COLUMN [VideoLink] NVARCHAR(512)  NOT NULL; ALTER TABLE dbo.[ProductUsage]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[Thumbnail]  ALTER COLUMN [ActorKey] NVARCHAR(200)  NOT NULL; ALTER TABLE dbo.[SkuLocalization]  ALTER COLUMN [Locale] NVARCHAR(8)  NOT NULL; ALTER TABLE dbo.[SkuLocalization]  ALTER COLUMN [UnitOfMeasure] NVARCHAR(150)  NOT NULL; ALTER TABLE dbo.[SkuLocalization]  ALTER COLUMN [SwatchColor] NVARCHAR(50)  NOT NULL; etc.. GO ALTER TABLE Locale ADD CONSTRAINT PK_Locale PRIMARY KEY (LocaleId) ALTER TABLE Country ADD CONSTRAINT PK_Country PRIMARY KEY (CountryId) Note that this alter is non-destructive to the data.   Hope this helps.

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• determine collision angle on a rotating body

  - by jorb

  update: new diagram and updated description I have a contact listener set up to try and determine the side that a collision happened at relative to the a bodies rotation. One way to solve this is to find the value of the yellow angle between the red and blue vectors drawn above. The angle can be found by taking the arc cosine of the dot product of the two vectors (Evan pointed this out). One of my points of confusion is the difference in domain of the atan2 function html canvas coordinates and the Box2d rotation information. I know I have to account for this somehow... SS below questions: Does Box2D provide these angles more directly in the collision information? Am I even on the right track? If so, any hints? I have the following javascript so far: Ship.prototype.onCollide = function (other_ent,cx,cy) { var pos = this.body.GetPosition(); //collision position relative to body var d_cx = pos.x - cx; var d_cy = pos.y - cy; //length of initial vector var len = Math.sqrt(Math.pow(pos.x -cx,2) + Math.pow(pos.y-cy,2)); //body angle - can over rotate hence mod 2*Pi var ang = this.body.GetAngle() % (Math.PI * 2); //vector representing body's angle - same magnitude as the first var b_vx = len * Math.cos(ang); var b_vy = len * Math.sin(ang); //dot product of the two vectors var dot_prod = d_cx * b_vx + d_cy * b_vy; //new calculation of difference in angle - NOT WORKING! var d_ang = Math.acos(dot_prod); var side; if (Math.abs(d_ang) < Math.PI/2 ) side = "front"; else side = "back"; console.log("length",len); console.log("pos:",pos.x,pos.y); console.log("offs:",d_cx,d_cy); console.log("body vec",b_vx,b_vy); console.log("body angle:",ang); console.log("dot product",dot_prod); console.log("result:",d_ang); console.log("side",side); console.log("------------------------"); }

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• Is SOAP Http POST more complicated than I thought

  - by Pete Petersen

  I'm currently writing a bit of code to send some xml data to a web service via HTTP POST. I thought this would be really simple and have written the following example code (C#) Console.WriteLine("Press enter to send data..."); while (Console.ReadLine() != "q") { HttpWebRequest httpWReq = (HttpWebRequest)WebRequest.Create(@"http://localhost:8888/"); Foo fooItem = new Foo { Member1 = "05", Member2 = "74455604", Member3 = "15101051", Member4 = 1, Member5 = "fsf", Member6 = 6.52, }; ASCIIEncoding encoding = new ASCIIEncoding(); string postData = fooItem.ToXml(); byte[] data = encoding.GetBytes(postData); httpWReq.Method = "POST"; httpWReq.ContentType = "application/xml"; httpWReq.ContentLength = data.Length; using (Stream stream = httpWReq.GetRequestStream()) { stream.Write(data, 0, data.Length); } HttpWebResponse response = (HttpWebResponse)httpWReq.GetResponse(); string responseString = new StreamReader(response.GetResponseStream()).ReadToEnd(); Console.WriteLine("Received " + responseString); Console.WriteLine("Press enter to send data..."); } This is all I thought would be necessary, however I have now been given the details for the web service. This included some information which is unfarmiliar to me and I'm unsure whether I need to include it. The information I was sent was <url>http://sometext/soap/rpc</url> <namespace>http://sometext/a.services</namespace> <method>receiveInfo</method> <parm-id>xmldata</parm-id> (Input data) (Actual XML data as string) <parm-id>status</parm-id> (Output data) <userid>user</userid> <password>pass</password> <secure>false</secure> I guess this means I need to include a username and password somehow, but I'm not sure what the namespace or method fields are used for. Could anyone give me a hint? Sorry I've never used webservices before.

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• Checking if an Unloaded Collection Contains Elements

  - by Ricardo Peres

  If you want to know if an unloaded collection in an entity contains elements, or count them, without actually loading them, you need to use a custom query; that is because the Count property (if the collection is not mapped with lazy=”extra”) and the LINQ Count() and Any() methods force the whole collection to be loaded. You can use something like these two methods, one for checking if there are any values, the other for actually counting them: 1: public static Boolean Exists(this ISession session, IEnumerable collection) 2: { 3: if (collection is IPersistentCollection) 4: { 5: IPersistentCollection col = collection as IPersistentCollection; 6:  7: if (col.WasInitialized == false) 8: { 9: String[] roleParts = col.Role.Split('.'); 10: String ownerTypeName = String.Join(".", roleParts, 0, roleParts.Length - 1); 11: String ownerCollectionName = roleParts.Last(); 12: String hql = "select 1 from " + ownerTypeName + " it where it.id = :id and exists elements(it." + ownerCollectionName + ")"; 13: Boolean exists = session.CreateQuery(hql).SetParameter("id", col.Key).List().Count == 1; 14:  15: return (exists); 16: } 17: } 18:  19: return ((collection as IEnumerable).OfType<Object>().Any()); 20: } 21:  22: public static Int64 Count(this ISession session, IEnumerable collection) 23: { 24: if (collection is IPersistentCollection) 25: { 26: IPersistentCollection col = collection as IPersistentCollection; 27:  28: if (col.WasInitialized == false) 29: { 30: String[] roleParts = col.Role.Split('.'); 31: String ownerTypeName = String.Join(".", roleParts, 0, roleParts.Length - 1); 32: String ownerCollectionName = roleParts.Last(); 33: String hql = "select count(elements(it." + ownerCollectionName + ")) from " + ownerTypeName + " it where it.id = :id"; 34: Int64 count = session.CreateQuery(hql).SetParameter("id", col.Key).UniqueResult<Int64>(); 35:  36: return (count); 37: } 38: } 39:  40: return ((collection as IEnumerable).OfType<Object>().Count()); 41: } Here’s how: 1: MyEntity entity = session.Load(100); 2:  3: if (session.Exists(entity.SomeCollection)) 4: { 5: Int32 count = session.Count(entity.SomeCollection); 6: //... 7: }

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• Why enumerator structs are a really bad idea (redux)

  - by Simon Cooper

  My previous blog post went into some detail as to why calling MoveNext on a BCL generic collection enumerator didn't quite do what you thought it would. This post covers the Reset method. To recap, here's the simple wrapper around a linked list enumerator struct from my previous post (minus the readonly on the enumerator variable): sealed class EnumeratorWrapper : IEnumerator<int> { private LinkedList<int>.Enumerator m_Enumerator; public EnumeratorWrapper(LinkedList<int> linkedList) { m_Enumerator = linkedList.GetEnumerator(); } public int Current { get { return m_Enumerator.Current; } } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { return m_Enumerator.MoveNext(); } public void Reset() { ((System.Collections.IEnumerator)m_Enumerator).Reset(); } public void Dispose() { m_Enumerator.Dispose(); } } If you have a look at the Reset method, you'll notice I'm having to cast to IEnumerator to be able to call Reset on m_Enumerator. This is because the implementation of LinkedList<int>.Enumerator.Reset, and indeed of all the other Reset methods on the BCL generic collection enumerators, is an explicit interface implementation. However, IEnumerator is a reference type. LinkedList<int>.Enumerator is a value type. That means, in order to call the reset method at all, the enumerator has to be boxed. And the IL confirms this: .method public hidebysig newslot virtual final instance void Reset() cil managed { .maxstack 8 L_0000: nop L_0001: ldarg.0 L_0002: ldfld valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator<int32> EnumeratorWrapper::m_Enumerator L_0007: box [System]System.Collections.Generic.LinkedList`1/Enumerator<int32> L_000c: callvirt instance void [mscorlib]System.Collections.IEnumerator::Reset() L_0011: nop L_0012: ret } On line 0007, we're doing a box operation, which copies the enumerator to a reference object on the heap, then on line 000c calling Reset on this boxed object. So m_Enumerator in the wrapper class is not modified by the call the Reset. And this is the only way to call the Reset method on this variable (without using reflection). Therefore, the only way that the collection enumerator struct can be used safely is to store them as a boxed IEnumerator<T>, and not use them as value types at all.

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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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• Too much delay while sending object over UDP to server

  - by RomZes

  I'm getting 4 sec delay when sending objects over UDP. Working on small game and trying to implement multiplayer. For now just trying to synchronize movements of 2 balls on the screen. StartingPoint.java is my server(first player), that receiving serialized objects (coordinates). SecondPlayer.java is client that sending serialized objects to server. When I'm moving my first object it appears 4 seconds later on different screen. StartingPoint.java @Override public void run() { byte[] receiveData = new byte[256]; byte[] sendData = new byte[256]; // DatagramSocket socketS; try { socket = new DatagramSocket(5000); System.out.println("Socket created on "+ port + " port"); } catch (SocketException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } while(true){ b1.update(this); b3.update(); System.out.println("Starting server..."); //// Receiving and deserializing object try { //socket.setSoTimeout(1000); DatagramPacket packet = new DatagramPacket(buf, buf.length); socket.receive(packet); byte[] data = packet.getData(); ByteArrayInputStream in = new ByteArrayInputStream(data); ObjectInputStream is = new ObjectInputStream(in); // socket.setSoTimeout(300); b1 = (Ball) is.readObject(); } catch (IOException | ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } repaint(); try { Thread.sleep(17); } catch (InterruptedException e) { e.printStackTrace(); } SecondPlayer.java @Override public void run() { while(true){ b.update(); networkSend(); repaint(); try { Thread.sleep(17); } catch (InterruptedException e) { e.printStackTrace(); } } public void networkSend(){ // Serialize to a byte array try { ByteArrayOutputStream bStream = new ByteArrayOutputStream(); ObjectOutputStream oo; oo = new ObjectOutputStream(bStream); oo.writeObject(b); oo.flush(); oo.close(); byte[] bufCar = bStream.toByteArray(); //socket = new DatagramSocket(); //socket.setSoTimeout(1000); InetAddress address = InetAddress.getByName("localhost"); DatagramPacket packet = new DatagramPacket(bufCar, bufCar.length, address, port); socket.send(packet); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }

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• New ZFS Encryption features in Solaris 11.1

  - by darrenm

  Solaris 11.1 brings a few small but significant improvements to ZFS dataset encryption.  There is a new readonly property 'keychangedate' that shows that date and time of the last wrapping key change (basically the last time 'zfs key -c' was run on the dataset), this is similar to the 'rekeydate' property that shows the last time we added a new data encryption key. $ zfs get creation,keychangedate,rekeydate rpool/export/home/bob NAME PROPERTY VALUE SOURCE rpool/export/home/bob creation Mon Mar 21 11:05 2011 - rpool/export/home/bob keychangedate Fri Oct 26 11:50 2012 local rpool/export/home/bob rekeydate Tue Oct 30 9:53 2012 local The above example shows that we have changed both the wrapping key and added new data encryption keys since the filesystem was initially created.  If we haven't changed a wrapping key then it will be the same as the creation date.  It should be obvious but for filesystems that were created prior to Solaris 11.1 we don't have this data so it will be displayed as '-' instead. Another change that I made was to relax the restriction that the size of the wrapping key needed to match the size of the data encryption key (ie the size given in the encryption property).  In Solaris 11 Express and Solaris 11 if you set encryption=aes-256-ccm we required that the wrapping key be 256 bits in length.  This restriction was unnecessary and made it impossible to select encryption property values with key lengths 128 and 192 when the wrapping key was stored in the Oracle Key Manager.  This is because currently the Oracle Key Manager stores AES 256 bit keys only.  Now with Solaris 11.1 this restriciton has been removed. There is still one case were the wrapping key size and data encryption key size will always match and that is where they keysource property sets the format to be 'passphrase', since this is a key generated internally to libzfs and to preseve compatibility on upgrade from older releases the code will always generate a wrapping key (using PKCS#5 PBKDF2 as before) that matches the key length size of the encryption property. The pam_zfs_key module has been updated so that it allows you to specify encryption=off. There were also some bugs fixed including not attempting to load keys for datasets that are delegated to zones and some other fixes to error paths to ensure that we could support Zones On Shared Storage where all the datasets in the ZFS pool were encrypted that I discussed in my previous blog entry. If there are features you would like to see for ZFS encryption please let me know (direct email or comments on this blog are fine, or if you have a support contract having your support rep log an enhancement request).

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• SFML 2.0 Too Many Variables in Class Preventing Draw To Screen

  - by Josh

  This is a very strange phenomenon to me. I have a class definition for a game, but when I add another variable to the class, the draw method does not print everything to the screen. It will be easier understood showing the code and output. Code for good draw output: class board { protected: RectangleShape rect; int top, left; int i, j; int rowSelect, columnSelect; CircleShape circleArr[4][10]; CircleShape codeArr[4]; CircleShape keyArr[4][10]; //int pegPresent[4]; public: board(void); void draw(RenderWindow& Window); int mouseOver(RenderWindow& Window); void placePeg(RenderWindow& Window, int pegSelect); }; Screen: Code for missing draw: class board { protected: RectangleShape rect; int top, left; int i, j; int rowSelect, columnSelect; CircleShape circleArr[4][10]; CircleShape codeArr[4]; CircleShape keyArr[4][10]; int pegPresent[4]; public: board(void); void draw(RenderWindow& Window); int mouseOver(RenderWindow& Window); void placePeg(RenderWindow& Window, int pegSelect); }; Screen: As you can see, all I do is un-comment the protected array and most of the pegs are gone from the right hand side. I have checked and made sure that I didn't accidentally created a variable with that name already. I haven't used it anywhere. Why does it not draw the remaining pegs as it should? My only thought is that maybe I am declaring too many variables for the class, but that doesn't really make sense to me. Any thoughts and help is greatly appreciated.

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• Pointers in C vs No pointers in PHP

  - by AnnaBanana

  Both languages have the same syntax. Why does C have the weird * character that denotes pointers (which is some kind of memory address of the variable contents?), when PHP doesn't have it and you can do pretty much the same things in PHP that you can do in C, without pointers? I guess the PHP compiler handles this internally, why doesn't C do the same? Doesn't this add unneeded complexity in C? For example I don't understand them :)

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• Configuring Full-Text Search for pdf and docx files

  - by Lukasz Kurylo

  I think in may I was creating a little filters module based on Full Text-Search. I have configured my dev machine, the same for two testing servers – in our company for internal testing before we deployed it to client, and then on the testing client server. Until last week this build  was still on the testing server and finally we got feedback that we can deploy it on the production one. I only say that, I lost half a day because I had not correctly remembered what I was doing to configure the FTS on the previous servers and I had no notes for that. I foolishly believed in my memory. Lesson learned.   For future reference a bunch of steps to configure the FTS for searching in *.pdf and *.docx files (and by the way in other Office files like *.xlsx).   1. From the page (link) download and install the *.pdf IFilter for FTS. 2. To the PATH global system variable add path to the catalog, where you installed the plugin. Default for this version is: C:\Program Files\Adobe\Adobe PDF iFilter 9 for 64-bit platforms\bin 3. From the page (link) download a FilterPackx64.exe and install it. 4. Now from SSMS execute the following procedures: -sp_fulltext_service 'load_os_resources',1 -sp_fulltext_service 'verify_signature', 0 5. Restart the server 6. Now we must check if the plugins are visible: -select document_type, path from sys.fulltext_document_types where document_type = '.pdf' -select document_type, path from sys.fulltext_document_types where document_type = '.docx' 7. If we see a result, then we can assume that everything is ok*. 8. Right now we can create a catalog for FTS and indexes on appropriate columns.     *I lost a lot of hours to find out, why the plugin for the *.pdf files wasn’t indexed any file in the database, but in the sys.fulltext_document_types table there was available a line for this plugin. After the deeper investigation I found that the *.pdf files actually were indexed. At least the EOF sign was added to the indexes and nothing more for each file. In the end the problem was that, I forgot to add the /bin in the path to the plugin in PATH variable..

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• 1.6 or 1.7: Browser side Java version for Oracle VM console

  - by katsumii

  I noticed one of the recent FAQ in OVM forum is about console.OTN Discussion Forums : Oracle VM Server for x86vnc console not running on Oracle VM 3.1.1 One of the variable for running console is Java version. I myself hit the bug below on Windows with JDK1.7 This is Windows only bug. I had success with JDK1.7 on Linux.Bug ID: 7191616 javaws.exe crashes when starting jnlp filejnlp file provided in the steps to reproduce always crashes javaws.exe in Java 7 Update 6.No problems in Update 4

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• We've completed the first iteration

  - by CliveT

  There are a lot of features in C# that are implemented by the compiler and not by the underlying platform. One such feature is a lambda expression. Since local variables cannot be accessed once the current method activation finishes, the compiler has to go out of its way to generate a new class which acts as a home for any variable whose lifetime needs to be extended past the activation of the procedure. Take the following example:     Random generator = new Random();     Func func = () = generator.Next(10); In this case, the compiler generates a new class called c_DisplayClass1 which is marked with the CompilerGenerated attribute. [CompilerGenerated] private sealed class c__DisplayClass1 {     // Fields     public Random generator;     // Methods     public int b__0()     {         return this.generator.Next(10);     } } Two quick comments on this: (i)    A display was the means that compilers for languages like Algol recorded the various lexical contours of the nested procedure activations on the stack. I imagine that this is what has led to the name. (ii)    It is a shame that the same attribute is used to mark all compiler generated classes as it makes it hard to figure out what they are being used for. Indeed, you could imagine optimisations that the runtime could perform if it knew that classes corresponded to certain high level concepts. We can see that the local variable generator has been turned into a field in the class, and the body of the lambda expression has been turned into a method of the new class. The code that builds the Func object simply constructs an instance of this class and initialises the fields to their initial values.     c__DisplayClass1 class2 = new c__DisplayClass1();     class2.generator = new Random();     Func func = new Func(class2.b__0); Reflector already contains code to spot this pattern of code and reproduce the form containing the lambda expression, so this is example is correctly decompiled. The use of compiler generated code is even more spectacular in the case of iterators. C# introduced the idea of a method that could automatically store its state between calls, so that it can pick up where it left off. The code can express the logical flow with yield return and yield break denoting places where the method should return a particular value and be prepared to resume.         {             yield return 1;             yield return 2;             yield return 3;         } Of course, there was already a .NET pattern for expressing the idea of returning a sequence of values with the computation proceeding lazily (in the sense that the work for the next value is executed on demand). This is expressed by the IEnumerable interface with its Current property for fetching the current value and the MoveNext method for forcing the computation of the next value. The sequence is terminated when this method returns false. The C# compiler links these two ideas together so that an IEnumerator returning method using the yield keyword causes the compiler to produce the implementation of an Iterator. Take the following piece of code.         IEnumerable GetItems()         {             yield return 1;             yield return 2;             yield return 3;         } The compiler implements this by defining a new class that implements a state machine. This has an integer state that records which yield point we should go to if we are resumed. It also has a field that records the Current value of the enumerator and a field for recording the thread. This latter value is used for optimising the creation of iterator instances. [CompilerGenerated] private sealed class d__0 : IEnumerable, IEnumerable, IEnumerator, IEnumerator, IDisposable {     // Fields     private int 1__state;     private int 2__current;     public Program 4__this;     private int l__initialThreadId; The body gets converted into the code to construct and initialize this new class. private IEnumerable GetItems() {     d__0 d__ = new d__0(-2);     d__.4__this = this;     return d__; } When the class is constructed we set the state, which was passed through as -2 and the current thread. public d__0(int 1__state) {     this.1__state = 1__state;     this.l__initialThreadId = Thread.CurrentThread.ManagedThreadId; } The state needs to be set to 0 to represent a valid enumerator and this is done in the GetEnumerator method which optimises for the usual case where the returned enumerator is only used once. IEnumerator IEnumerable.GetEnumerator() {     if ((Thread.CurrentThread.ManagedThreadId == this.l__initialThreadId)               && (this.1__state == -2))     {         this.1__state = 0;         return this;     } The state machine itself is implemented inside the MoveNext method. private bool MoveNext() {     switch (this.1__state)     {         case 0:             this.1__state = -1;             this.2__current = 1;             this.1__state = 1;             return true;         case 1:             this.1__state = -1;             this.2__current = 2;             this.1__state = 2;             return true;         case 2:             this.1__state = -1;             this.2__current = 3;             this.1__state = 3;             return true;         case 3:             this.1__state = -1;             break;     }     return false; } At each stage, the current value of the state is used to determine how far we got, and then we generate the next value which we return after recording the next state. Finally we return false from the MoveNext to signify the end of the sequence. Of course, that example was really simple. The original method body didn't have any local variables. Any local variables need to live between the calls to MoveNext and so they need to be transformed into fields in much the same way that we did in the case of the lambda expression. More complicated MoveNext methods are required to deal with resources that need to be disposed when the iterator finishes, and sometimes the compiler uses a temporary variable to hold the return value. Why all of this explanation? We've implemented the de-compilation of iterators in the current EAP version of Reflector (7). This contrasts with previous version where all you could do was look at the MoveNext method and try to figure out the control flow. There's a fair amount of things we have to do. We have to spot the use of a CompilerGenerated class which implements the Enumerator pattern. We need to go to the class and figure out the fields corresponding to the local variables. We then need to go to the MoveNext method and try to break it into the various possible states and spot the state transitions. We can then take these pieces and put them back together into an object model that uses yield return to show the transition points. After that Reflector can carry on optimising using its usual optimisations. The pattern matching is currently a little too sensitive to changes in the code generation, and we only do a limited analysis of the MoveNext method to determine use of the compiler generated fields. In some ways, it is a pity that iterators are compiled away and there is no metadata that reflects the original intent. Without it, we are always going to dependent on our knowledge of the compiler's implementation. For example, we have noticed that the Async CTP changes the way that iterators are code generated, so we'll have to do some more work to support that. However, with that warning in place, we seem to do a reasonable job of decompiling the iterators that are built into the framework. Hopefully, the EAP will give us a chance to find examples where we don't spot the pattern correctly or regenerate the wrong code, and we can improve things. Please give it a go, and report any problems.

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• Making Those PanelBoxes Behave

  - by Duncan Mills

  I have a little problem to solve earlier this week - misbehaving <af:panelBox> components... What do I mean by that? Well here's the scenario, I have a page fragment containing a set of panelBoxes arranged vertically. As it happens, they are stamped out in a loop but that does not really matter. What I want to be able to do is to provide the user with a simple UI to close and open all of the panelBoxes in concert. This could also apply to showDetailHeader and similar items with a disclosed attrubute, but in this case it's good old panelBoxes.  Ok, so the basic solution to this should be self evident. I can set up a suitable scoped managed bean that the panelBoxes all refer to for their disclosed attribute state. Then the open all / close commandButtons in the UI can simply set the state of that bean for all the panelBoxes to pick up via EL on their disclosed attribute. Sound OK? Well that works basically without a hitch, but turns out that there is a slight problem and this is where the framework is attempting to be a little too helpful. The issue is that is the user manually discloses or hides a panelBox then that will override the value that the EL is setting. So for example. I start the page with all panelBoxes collapsed, all set by the EL state I'm storing on the session I manually disclose panelBox no 1. I press the Expand All button - all works as you would hope and all the panelBoxes are now disclosed, including of course panelBox 1 which I just expanded manually. Finally I press the Collapse All button and everything collapses except that first panelBox that I manually disclosed.  The problem is that the component remembers this manual disclosure and that overrides the value provided by the expression. If I change the viewId (navigate away and back) then the panelBox will start to behave again, until of course I touch it again! Now, the more astute amoungst you would think (as I did) Ah, sound like the MDS personalizaton stuff is getting in the way and the solution should simply be to set the dontPersist attribute to disclosed | ALL. Alas this does not fix the issue.  After a little noodling on the best way to approach this I came up with a solution that works well, although if you think of an alternative way do let me know. The principle is simple. In the disclosureListener for the panelBox I take a note of the clientID of the panelBox component that has been touched by the user along with the state. This all gets stored in a Map of Booleans in ViewScope which is keyed by clientID and stores the current disclosed state in the Boolean value.  The listener looks like this (it's held in a request scope backing bean for the page): public void handlePBDisclosureEvent(DisclosureEvent disclosureEvent) { String clientId = disclosureEvent.getComponent().getClientId(FacesContext.getCurrentInstance()); boolean state = disclosureEvent.isExpanded(); pbState.addTouchedPanelBox(clientId, state); } The pbState variable referenced here is a reference to the bean which will hold the state of the panelBoxes that lives in viewScope (recall that everything is re-set when the viewid is changed so keeping this in viewScope is just fine and cleans things up automatically). The addTouchedPanelBox() method looks like this: public void addTouchedPanelBox(String clientId, boolean state) { //create the cache if needed this is just a Map<String,Boolean> if (_touchedPanelBoxState == null) { _touchedPanelBoxState = new HashMap<String, Boolean>(); } // Simply put / replace _touchedPanelBoxState.put(clientId, state); } So that's the first part, we now have a record of every panelBox that the user has touched. So what do we do when the Collapse All or Expand All buttons are pressed? Here we do some JavaScript magic. Basically for each clientID that we have stored away, we issue a client side disclosure event from JavaScript - just as if the user had gone back and changed it manually. So here's the Collapse All button action: public String CloseAllAction() { submitDiscloseOverride(pbState.getTouchedClientIds(true), false); _uiManager.closeAllBoxes(); return null; }  The _uiManager.closeAllBoxes() method is just manipulating the master-state that all of the panelBoxes are bound to using EL. The interesting bit though is the line:  submitDiscloseOverride(pbState.getTouchedClientIds(true), false); To break that down, the first part is a call to that viewScoped state holder to ask for a list of clientIDs that need to be "tweaked": public String getTouchedClientIds(boolean targetState) { StringBuilder sb = new StringBuilder(); if (_touchedPanelBoxState != null && _touchedPanelBoxState.size() > 0) { for (Map.Entry<String, Boolean> entry : _touchedPanelBoxState.entrySet()) { if (entry.getValue() == targetState) { if (sb.length() > 0) { sb.append(','); } sb.append(entry.getKey()); } } } return sb.toString(); } You'll notice that this method only processes those panelBoxes that will be in the wrong state and returns those as a comma separated list. This is then processed by the submitDiscloseOverride() method: private void submitDiscloseOverride(String clientIdList, boolean targetDisclosureState) { if (clientIdList != null && clientIdList.length() > 0) { FacesContext fctx = FacesContext.getCurrentInstance(); StringBuilder script = new StringBuilder(); script.append("overrideDiscloseHandler('"); script.append(clientIdList); script.append("',"); script.append(targetDisclosureState); script.append(");"); Service.getRenderKitService(fctx, ExtendedRenderKitService.class).addScript(fctx, script.toString()); } } This method constructs a JavaScript command to call a routine called overrideDiscloseHandler() in a script attached to the page (using the standard <af:resource> tag). That method parses out the list of clientIDs and sends the correct message to each one: function overrideDiscloseHandler(clientIdList, newState) { AdfLogger.LOGGER.logMessage(AdfLogger.INFO, "Disclosure Hander newState " + newState + " Called with: " + clientIdList); //Parse out the list of clientIds var clientIdArray = clientIdList.split(','); for (var i = 0; i < clientIdArray.length; i++){ var panelBox = flipPanel = AdfPage.PAGE.findComponentByAbsoluteId(clientIdArray[i]); if (panelBox.getComponentType() == "oracle.adf.RichPanelBox"){ panelBox.broadcast(new AdfDisclosureEvent(panelBox, newState)); } }  }  So there you go. You can see how, with a few tweaks the same code could be used for other components with disclosure that might suffer from the same problem, although I'd point out that the behavior I'm working around here us usually desirable. You can download the running example (11.1.2.2) from here. 

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• Is code like this a "train wreck" (in violation of Law of Demeter)?

  - by Michael Kjörling

  Browsing through some code I've written, I came across the following construct which got me thinking. At a first glance, it seems clean enough. Yes, in the actual code the getLocation() method has a slightly more specific name which better describes exactly which location it gets. service.setLocation(this.configuration.getLocation().toString()); In this case, service is an instance variable of a known type, declared within the method. this.configuration comes from being passed in to the class constructor, and is an instance of a class implementing a specific interface (which mandates a public getLocation() method). Hence, the return type of the expression this.configuration.getLocation() is known; specifically in this case, it is a java.net.URL, whereas service.setLocation() wants a String. Since the two types String and URL are not directly compatible, some sort of conversion is required to fit the square peg in the round hole. However, according to the Law of Demeter as cited in Clean Code, a method f in class C should only call methods on C, objects created by or passed as arguments to f, and objects held in instance variables of C. Anything beyond that (the final toString() in my particular case above, unless you consider a temporary object created as a result of the method invocation itself, in which case the whole Law seems to be moot) is disallowed. Is there a valid reasoning why a call like the above, given the constraints listed, should be discouraged or even disallowed? Or am I just being overly nitpicky? If I were to implement a method URLToString() which simply calls toString() on a URL object (such as that returned by getLocation()) passed to it as a parameter, and returns the result, I could wrap the getLocation() call in it to achieve exactly the same result; effectively, I would just move the conversion one step outward. Would that somehow make it acceptable? (It seems to me, intuitively, that it should not make any difference either way, since all that does is move things around a little. However, going by the letter of the Law of Demeter as cited, it would be acceptable, since I would then be operating directly on a parameter to a function.) Would it make any difference if this was about something slightly more exotic than calling toString() on a standard type? When answering, do keep in mind that altering the behavior or API of the type that the service variable is of is not practical. Also, for the sake of argument, let's say that altering the return type of getLocation() is also impractical.

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• Why do some languages recommend using spaces rather than tabs?

  - by TK Kocheran

  Maybe I'm alone in this, but few things annoy me like people indenting using spaces rather than tabs. How is typing SpaceSpaceSpaceSpace easier and more intuitive than typing Tab? Sure, tab width is variable, but it's much more indicative of indentation space than spaces. The same thing goes for backspacing; backspace once or four times? Why do languages like Python recommend using spaces over tabs?

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• Google Analytics: Block Your Dynamic IP Visits?

  - by 4thSpace

  I have a dynamic IP, which doesn't work for Google Analytics IP filtering. I read this post How to excludes my visits from Google Analytics? but don't see any code for setting the variable mentioned there. Has anyone been able to block their website visits from Google Analytics using a cookie? EDIT: This seems to work https://tools.google.com/dlpage/gaoptout. Although I don't think it was designed as I'm using it.

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• ssh -X "Xt error: Can't open display: :0.0"

  - by Fabian

  I'm trying to open xterm on my remote server (Ubuntu Server 10.04) with ssh: ssh -X name@machine xterm but the error returned is: xterm Xt error: Can't open display: :0.0` I googled and tried everything I found. Still getting this error. The DISPLAY-variable should be set automatically, right? Part of sshd_config: X11Forwarding yes X11DisplayOffset 10 PrintMotd no PrintLastLog yes TCPKeepAlive yes Any advice?

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• Once installed geos library (C++, and C), and then trying to install rgeos package (R), it reports geos-config missing!

  - by user1873888

  Knowing that the package rgeos, from the R language, requieres a prior installation of geos libraries, I installed, both, libgeos and libgeos-c1 (3.2.2), using the synaptic installer in my Ubuntu 12.04 (32 bit) machine. Then I tried to install rgeos directly from the R console, and it issued a message in the sense that geos-config was not found. The output is as follows: > install.packages("rgeos") Installing package(s) into ‘/home/checo/R/i486-pc-linux-gnu-library/2.15’ (as ‘lib’ is unspecified) also installing the dependency ‘sp’ probando la URL 'http://cran.rstudio.com/src/contrib/sp_1.0-9.tar.gz' Content type 'application/x-gzip' length 882102 bytes (861 Kb) URL abierta ================================================== downloaded 861 Kb probando la URL 'http://cran.rstudio.com/src/contrib/rgeos_0.2-19.tar.gz' Content type 'application/x-gzip' length 221471 bytes (216 Kb) URL abierta ================================================== downloaded 216 Kb * installing *source* package ‘sp’ ... ** package ‘sp’ successfully unpacked and MD5 sums checked ** libs gcc -std=gnu99 -I/usr/share/R/include -DNDEBUG -fpic -O3 -pipe -g -c R centroid.c -o Rcentroid.o gcc -std=gnu99 -I/usr/share/R/include -DNDEBUG -fpic -O3 -pipe -g -c gcdist.c -o gcdist.o gcc -std=gnu99 -I/usr/share/R/include -DNDEBUG -fpic -O3 -pipe -g -c init.c -o init.o gcc -std=gnu99 -I/usr/share/R/include -DNDEBUG -fpic -O3 -pipe -g -c pip.c -o pip.o gcc -std=gnu99 -I/usr/share/R/include -DNDEBUG -fpic -O3 -pipe -g -c pip2.c -o pip2.o gcc -std=gnu99 -I/usr/share/R/include -DNDEBUG -fpic -O3 -pipe -g -c sp_xports.c -o sp_xports.o gcc -std=gnu99 -I/usr/share/R/include -DNDEBUG -fpic -O3 -pipe -g -c surfaceArea.c -o surfaceArea.o gcc -std=gnu99 -I/usr/share/R/include -DNDEBUG -fpic -O3 -pipe -g -c zerodist.c -o zerodist.o gcc -std=gnu99 -shared -o sp.so Rcentroid.o gcdist.o init.o pip.o pip2.o sp_xports.o surfaceArea.o zerodist.o -L/usr/lib/R/lib -lR installing to /home/checo/R/i486-pc-linux-gnu-library/2.15/sp/libs ** R ** data ** demo ** inst ** preparing package for lazy loading ** help *** installing help indices ** building package indices ** installing vignettes ‘intro_sp.Rnw’ ‘over.Rnw’ ** testing if installed package can be loaded * DONE (sp) * installing *source* package ‘rgeos’ ... ** package ‘rgeos’ successfully unpacked and MD5 sums checked configure: CC: gcc -std=gnu99 configure: CXX: g++ configure: rgeos: 0.2-17 checking for /usr/bin/svnversion... no configure: svn revision: 394 checking geos-config usability... ./configure: line 1385: geos-config: command not found no configure: error: geos-config not usable ERROR: configuration failed for package ‘rgeos’ * removing ‘/home/checo/R/i486-pc-linux-gnu-library/2.15/rgeos’ Warning in install.packages : installation of package ‘rgeos’ had non-zero exit status Forgive my ignorance, but I don't know where this file, "geos-config", comes from: should it be generated by the gcc compilations above, or should it be previously installed when the libgeos libraries were intalled? I learnt, from another machine, that "geos-config" is an executable and that it should be installed in /usr/bin. Do you have any idea on what's wrong with my procedure? Thanks, -Sergio.

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• Validate if aTextBox Value Start with a Specific Letter

  - by Vincent Maverick Durano

  In case you will be working on a page that needs to validate the first character of the TextBox entered by a user then here are two options that you can use: Option 1: Using an array   1: <asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server"> 2: <script type="text/javascript"> 3: function CheckFirstChar(o) { 4: var arr = ['A', 'B', 'C', 'D']; 5: if (o.value.length > 0) { 6: for (var i = 0; i < arr.length; i++) { 7: if (o.value.charAt(0) == arr[i]) { 8: alert('Valid'); 9: return true; 10: } 11: else { 12: alert('InValid'); 13: return false; 14: } 15: } 16: } 17: } 18: </script> 19: </asp:Content> 20: <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> 21: <asp:TextBox ID="TextBox1" runat="server" onblur="return CheckFirstChar(this);"></asp:TextBox> 22: </asp:Content>   The example above uses an array of string for storing the list of  characters that a TextBox value should start with. We then iterate to the array and compare the first character of TextBox value to see if it matches any characters from the array. Option 2: Using Regular Expression (Preferred way)   1: <asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server"> 2: <script type="text/javascript"> 3: function CheckFirstChar(o) { 4: pattern = /^(A|B|C|D)/; 5: if (!pattern.test(o.value)) { 6: alert('InValid'); 7: return false; 8: } else { 9: alert('Valid'); 10: return true; 11: } 12: } 13: </script> 14: </asp:Content> 15: <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> 16: <asp:TextBox ID="TextBox1" runat="server" onblur="return CheckFirstChar(this);"></asp:TextBox> 17: </asp:Content>   The example above uses regular expression with the pattern  /^(A|B|C|D)/. This will check if the TextBox value starts with A,B,C or D. Please note that it's case sensitive. If you want to allow lower case then you can alter the patter to this /^(A|B|C|D)/i. The i in the last part will cause a case-insensitive search.   That's it! I hope someone find this post useful!

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• Are closures with side-effects considered "functional style"?

  - by Giorgio

  Many modern programming languages support some concept of closure, i.e. of a piece of code (a block or a function) that Can be treated as a value, and therefore stored in a variable, passed around to different parts of the code, be defined in one part of a program and invoked in a totally different part of the same program. Can capture variables from the context in which it is defined, and access them when it is later invoked (possibly in a totally different context). Here is an example of a closure written in Scala: def filterList(xs: List[Int], lowerBound: Int): List[Int] = xs.filter(x => x >= lowerBound) The function literal x => x >= lowerBound contains the free variable lowerBound, which is closed (bound) by the argument of the function filterList that has the same name. The closure is passed to the library method filter, which can invoke it repeatedly as a normal function. I have been reading a lot of questions and answers on this site and, as far as I understand, the term closure is often automatically associated with functional programming and functional programming style. The definition of function programming on wikipedia reads: In computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state. and further on [...] in functional code, the output value of a function depends only on the arguments that are input to the function [...]. Eliminating side effects can make it much easier to understand and predict the behavior of a program, which is one of the key motivations for the development of functional programming. On the other hand, many closure constructs provided by programming languages allow a closure to capture non-local variables and change them when the closure is invoked, thus producing a side effect on the environment in which they were defined. In this case, closures implement the first idea of functional programming (functions are first-class entities that can be moved around like other values) but neglect the second idea (avoiding side-effects). Is this use of closures with side effects considered functional style or are closures considered a more general construct that can be used both for a functional and a non-functional programming style? Is there any literature on this topic? IMPORTANT NOTE I am not questioning the usefulness of side-effects or of having closures with side effects. Also, I am not interested in a discussion about the advantages / disadvantages of closures with or without side effects. I am only interested to know if using such closures is still considered functional style by the proponent of functional programming or if, on the contrary, their use is discouraged when using a functional style.

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