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• When using Direct3D, how much math is being done on the CPU?

  - by zirgen

  Context: I'm just starting out. I'm not even touching the Direct3D 11 API, and instead looking at understanding the pipeline, etc. From looking at documentation and information floating around the web, it seems like some calculations are being handled by the application. That, is, instead of simply presenting matrices to multiply to the GPU, the calculations are being done by a math library that operates on the CPU. I don't have any particular resources to point to, although I guess I can point to the XNA Math Library or the samples shipped in the February DX SDK. When you see code like mViewProj = mView * mProj;, that projection is being calculated on the CPU. Or am I wrong? If you were writing a program, where you can have 10 cubes on the screen, where you can move or rotate cubes, as well as viewpoint, what calculations would you do on the CPU? I think I would store the geometry for the a single cube, and then transform matrices representing the actual instances. And then it seems I would use the XNA math library, or another of my choosing, to transform each cube in model space. Then get the coordinates in world space. Then push the information to the GPU. That's quite a bit of calculation on the CPU. Am I wrong? Am I reaching conclusions based on too little information and understanding? What terms should I Google for, if the answer is STFW? Or if I am right, why aren't these calculations being pushed to the GPU as well?

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• TCP Socket.Connect is generating false positives

  - by Mark

  I'm experiencing really weird behavior with the Socket.Connect method in C#. I am attempting a TCP Socket.Connect to a valid IP but closed port and the method is continuing as if I have successfully connected. When I packet sniffed what was going on I saw that the app was receiving RST packets from the remote machine. Yet from the tracing that is in place it is clear that the connect method is not throwing an exception. Any ideas what might be causing this? The code that is running is basically this IPEndPoint iep = new IPEndPoint(System.Net.IPAddress.Parse(m_ipAddress), m_port); Socket tcpSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); tcpSocket.Connect(iep); To add to the mystery... when running this code in a stand alone console application, the result is as expected – the connect method throws an exception. However, when running it in the Windows Service deployment we have the connect method does not throw an exception. Edit in response to Mystere Man's answer How would the exception be swallowed? I have a Trace.WriteLine right above the .Connect method and a Trace.WriteLine right under it (not shown in the code sample for readability). I know that both traces are running. I also have a try catch around the whole thing which also does a Trace.Writeline and I don't see that in the log files anywhere. I have also enabled the internal socket tracing as you suggested. I don't see any exceptions. I see what appears to be successful connections. I am trying to identify differences between the windows service app and the diagnostic console app I made. I am running out of ideas though End edit Thanks

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• Cross Thread problem C#

  - by Frederik Witte

  Hello people - I got this code (lg_log is a listbox, and i want it to log the start_server.bat) Here is the code i got: public void bt_play_Click(object sender, EventArgs e) { lg_log.Items.Add("Starting Mineme server .."); string directory = Directory.GetCurrentDirectory(); var info = new ProcessStartInfo(directory + @"\start_base.bat") {UseShellExecute = false, RedirectStandardOutput = true, CreateNoWindow = true, WorkingDirectory = directory + @"\Servers\Base"}; var proc = new Process { StartInfo = info, EnableRaisingEvents = true }; proc.OutputDataReceived += (obj, args) => { if (args.Data != null) { lg_log.Items.Add(args.Data); } }; proc.Start(); proc.BeginOutputReadLine(); lg_log.Items.Add("Server is now running!"); proc.WaitForExit(); } When i run this, i'll get an error .. Anybody can help me? I'll rate the answer up! :D Edit: The error i get is this: System.InvalidOperationException Hope it helps :) The error comes at the lg_log.Items.Add(args.Data); code line

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• Why is it that an int in C++ that isnt initialized (then used) doesn't return an error?

  - by omizzle

  I am new to C++ (just starting). I come from a Java background and I was trying out the following piece of code that would sum the numbers between 1 and 10 (inclusive) and then print out the sum: /* * File: main.cpp * Author: omarestrella * * Created on June 7, 2010, 8:02 PM */ #include <cstdlib> #include <iostream> using namespace std; int main() { int sum; for(int x = 1; x <= 10; x++) { sum += x; } cout << "The sum is: " << sum << endl; return 0; } When I ran it it kept printing 32822 for the sum. I knew the answer was supposed to be 55 and realized that its print the max value for a short (32767) plus 55. Changing int sum; to int sum = 0; would work (as it should, since the variable needs to be initialized!). Why does this behavior happen, though? Why doesnt the compiler warn you about something like this? I know Java screams at you when something isnt initialized. Thank you.

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• How to catch unintentional function interpositioning with GCC?

  - by SiegeX

  Reading through my book Expert C Programming, I came across the chapter on function interpositioning and how it can lead to some serious hard to find bugs if done unintentionally. The example given in the book is the following: my_source.c mktemp() { ... } main() { mktemp(); getwd(); } libc mktemp(){ ... } getwd(){ ...; mktemp(); ... } According to the book, what happens in main() is that mktemp() (a standard C library function) is interposed by the implementation in my_source.c. Although having main() call my implementation of mktemp() is intended behavior, having getwd() (another C library function) also call my implementation of mktemp() is not. Apparently, this example was a real life bug that existed in SunOS 4.0.3's version of lpr. The book goes on to explain the fix was to add the keyword static to the definition of mktemp() in my_source.c; although changing the name altogether should have fixed this problem as well. This chapter leaves me with some unresolved questions that I hope you guys could answer: Should our software group adopt the practice of putting the keyword static in front of all functions that we don't want to be exposed? Does GCC have a way to warn about function interposition? We certainly don't ever intend on this happening and I'd like to know about it if it does. Can interposition happen with functions introduced by static libraries? Thanks for the help.

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• Attempt to use a while loop for the 'next' arg of a for loop generates #arg error

  - by JerryK

  Am attempting to teach myself to program using Tcl. The task i've set myself to motivate my learning of Tcl is to solve the 8 queens problem. My approach to creating a program is to successively 'prototype' a solution. I have asked an earlier question related to the correctly laying out the nested for loops and received a helpful answer. To my dismay I find that the next development of my code creates the same interpreter error : "wrong # args" I have been careful to have an open brace at the end of the line preceding the while loop command. I've also tried to put the arguments of the whileloop in braces. This generates a different error. I have sincerely tried to understand the Tcl syntax man page - not too successfully - suggested by the answerer of my earlier question. Here is the code set allowd 1 set notallowd 0 for {set r1p 1} {$r1p <= 8} {incr r1p } { puts "1st row q placed at $r1p" ;# re-initialize r2 'free for q placemnt' array after every change of r1 q pos: for {set i 1 } {$i <= 8} {incr i} { set r2($i) $allowd } for { set r2($r1p) $notallowd ; set r2([expr $r1p-1]) $notallowd ; set r2([expr $r1p+1]) $notallowd ; set r2p 1} {$r2p <= 8} { ;# 'next' arg of r2 forloop will be a whileloop : while r2($r2p)== $notallowd incr r2p } { puts "2nd row q placed at $r2p" ;# end of 'commnd' arg of r2 forloop } } Where am I going wrong? EDIT : to provide clear reply @slebetman As stated in my text, I did brace the arguments of the whileloop (indeed that was how i first wrote the code) below is exactly the layout of the r2 forloop tried: for { set r2($r1p) $notallowd ; set r2([expr $r1p-1]) $notallowd ; set r2([expr $r1p+1]) $notallowd ; set r2p 1} {$r2p <= 8} { ;# 'next' arg of r2 forloop will be a whileloop : while { r2($r2p)== $notallowd } { incr r2p } } { puts "2nd row q placed at $r2p" ;# end of 'commnd' arg of r2 forloop } but this generates the fatal interpreter error : "unknown math function 'r2' while compiling while { r2($r2p .... "

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• Beginner Ques::How to delete records permanently in case of linked tables?

  - by Serenity

  Let's say I have these 2 tables QuesType and Ques:- QuesType QuestypeID|QuesType |Active ------------------------------------ 101 |QuesType1 |True 102 |QuesType2 |True 103 |XXInActiveXX |False Ques QuesID|Ques|Answer|QUesTypeID|Active ------------------------------------ 1 |Ques1|Ans1 |101 |True 2 |Ques2|Ans2 |102 |True 3 |Ques3|Ans3 |101 |True In the QuesType Table:- QuesTypeID is a Primary key In the Ques Table:- QuesID is a Primary key and QuesType ID is the Foreign Key that refernces QuesTypeID from QuesType Table Now I am unable to delete records from QuesType Table, I can only make QuesType inactive by setting Active=False. I am unable to delete QuesTypes permanently because of the Foreign key relation it has with Ques Table. So , I just set the column Active=false and those Questypes then don't show on my grid wen its binded. What I want to do is be able to delete any QuesType permamnently. Now it can only be deleted if its not being used anywhere in the Ques table, right? So to delete any QuesType permanently I thot this is what I could do:- In the grid that displays QuesTypes, I have this check box for Active and a button for delete.What I thot was, when a user makes some QuesType inactive then OnCheckChanged() event will run and that will have the code to delete all the Questions in Ques table that are using that QuesTypeID. Then on the QuesType grid, that QuesType would show as Deactivated and only then can a user delete it permanently. Am I thinking correctly? Currently in my DeleteQuesType Stored Procedure what I am doing is:- Setting the Active=false and Setting QuesTye= some string like XXInactiveXX Is there any other way?

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• TortoiseSVN Error: "OPTIONS of 'https://...' could not connect to server (...)"

  - by Zack Peterson

  I'm trying to setup a new computer to synchronize with my SVN repository that's hosted with cvsdude.com. I get this error: Here's what I did (these have worked in the past): Downloaded and installed TortoiseSVN Created a new folder C:\aspwebsite Right-clicked, chose SVN Checkout... Entered the following information, clicked OK: URL of repository: https://<reponame>-svn.cvsdude.com/aspwebsite Checkout directory: C:\aspwebsite Checkout depth: Fully recursive Omit externals: Unchecked Revision: HEAD revision Got TortoiseSVN error: OPTIONS of 'https://<reponame>-svn.cvsdude.com/aspwebsite': could not connect to server (https://<reponame>-svn.cvsdude.com) Rather than getting the error, TortoiseSVN should have asked for my username and password and then downloaded about 90MB. Why can't I checkout from my Subversion repository? Kent Fredric wrote: Either their security certificate has expired, or their hosting is broken/down. Contact CVSDude and ask them whats up. It could also be a timeout, because for me their site is exhaustively slow.. It errors after only a couple seconds. I don't think it's a timeout. Matt wrote: Try visiting https://[redacted]-svn.cvsdude.com/aspwebsite and see what happens. If you can visit it in your browser, you ought to be able to get the files in your SVN client and we can work from there. If it fails, then there's your answer. I can access the site in a web browser.

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• ccfollow actions in cocos2d

  - by Srinivas

  ccfollow actions is following my projectile correctly. when, double tap recognised. see the below code. were am mistaken. here is my code:- - (void)update:(ccTime)dt { if (numTaps==1 ) { [self runAction:[CCFollow actionWithTarget:nextProjectile worldBoundary:CGRectMake(0,0,1050,350)]]; } } - (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { numTaps = [[touches anyObject] tapCount]; printf("Tapcount : %d",numTaps); if (numTaps ==1) { nextProjectile = [[CCSprite spriteWithFile:@"Weapon.png"] retain]; nextProjectile.position = ccp(nextprojectile .contentSize.width/2+65, nextprojectile.contentSize.height/2+70); [nextProjectile runAction:[CCSequence actions: [here's my nextprojectile actions],nil]]; } } after seen the above code. a question raised by you. why am mentioning the ccfollow action in if condition. answer is here, ordinarily, am mention in update function it will not works, when i set this if condition it works after double tap recognised. how to rectify this issue? any help would be highly appreciated.

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• Unit Testing - Algorithm or Sample based ?

  - by ohadsc

  Say I'm trying to test a simple Set class public IntSet : IEnumerable<int> { Add(int i) {...} //IEnumerable implementation... } And suppose I'm trying to test that no duplicate values can exist in the set. My first option is to insert some sample data into the set, and test for duplicates using my knowledge of the data I used, for example: //OPTION 1 void InsertDuplicateValues_OnlyOneInstancePerValueShouldBeInTheSet() { var set = new IntSet(); //3 will be added 3 times var values = new List<int> {1, 2, 3, 3, 3, 4, 5}; foreach (int i in values) set.Add(i); //I know 3 is the only candidate to appear multiple times int counter = 0; foreach (int i in set) if (i == 3) counter++; Assert.AreEqual(1, counter); } My second option is to test for my condition generically: //OPTION 2 void InsertDuplicateValues_OnlyOneInstancePerValueShouldBeInTheSet() { var set = new IntSet(); //The following could even be a list of random numbers with a duplicate var values = new List<int> { 1, 2, 3, 3, 3, 4, 5}; foreach (int i in values) set.Add(i); //I am not using my prior knowledge of the sample data //the following line would work for any data CollectionAssert.AreEquivalent(new HashSet<int>(values), set); } Of course, in this example, I conveniently have a set implementation to check against, as well as code to compare collections (CollectionAssert). But what if I didn't have either ? This is the situation when you are testing your real life custom business logic. Granted, testing for expected conditions generically covers more cases - but it becomes very similar to implementing the logic again (which is both tedious and useless - you can't use the same code to check itself!). Basically I'm asking whether my tests should look like "insert 1, 2, 3 then check something about 3" or "insert 1, 2, 3 and check for something in general" EDIT - To help me understand, please state in your answer if you prefer OPTION 1 or OPTION 2 (or neither, or that it depends on the case, etc )

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• Where are possible locations of queueing/buffering delays in Linux multicast?

  - by Matt

  We make heavy use of multicasting messaging across many Linux servers on a LAN. We are seeing a lot of delays. We basically send an enormous number of small packages. We are more concerned with latency than throughput. The machines are all modern, multi-core (at least four, generally eight, 16 if you count hyperthreading) machines, always with a load of 2.0 or less, usually with a load less than 1.0. The networking hardware is also under 50% capacity. The delays we see look like queueing delays: the packets will quickly start increasing in latency, until it looks like they jam up, then return back to normal. The messaging structure is basically this: in the "sending thread", pull messages from a queue, add a timestamp (using gettimeofday()), then call send(). The receiving program receives the message, timestamps the receive time, and pushes it in a queue. In a separate thread, the queue is processed, analyzing the difference between sending and receiving timestamps. (Note that our internal queues are not part of the problem, since the timestamps are added outside of our internal queuing.) We don't really know where to start looking for an answer to this problem. We're not familiar with Linux internals. Our suspicion is that the kernel is queuing or buffering the packets, either on the send side or the receive side (or both). But we don't know how to track this down and trace it. For what it's worth, we're using CentOS 4.x (RHEL kernel 2.6.9).

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• Serialization of Queue type not working

  - by Soham

  Consider this piece of code: private Queue Date=new Queue(); //other declarations public DateTime _Date { get { return (DateTime)Date.Peek();} set { Date.Enqueue(value); } } //other properties and stuff.... public void UpdatePosition(...) { //other code IFormatter formatter = new BinaryFormatter(); Stream Datestream = new MemoryStream(); formatter.Serialize(Datestream, Date); byte[] Datebin = new byte[2048]; Datestream.Read(Datebin,0,2048); //Debug-Bug Console.WriteLine(Convert.ToString(this._Date)); Console.WriteLine(BitConverter.ToString(Datebin, 0, 3)); //other code } The output of the first WriteLine is perfect. I.e to check if really the Queue is initialised or not. It is. The right variables are stored etc. (I inserted a value in that Queue, that part of the code is not shown.) But the second WriteLine is not giving the right expected answer: It serializes the entire Queue to 00-00-00.

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• Accessing program information that gdb sees in C++

  - by anon

  I have a program written in C++, on Linux, compiled with -g. When I run it under gdb, I can 1) set breakpoints 2) at those breakpoints, print out variables 3) see the stackframe 4) given a variable that's a structure, print out parts of the structure (i.e. how ddd displays information). Now, given that my program is compiled with "-g" -- is there anyway that I can access this power within my program itself? I.e. given that my program is compiled with "-g", is there some std::vector<string> getStackFrame(); function I can call to get the current stackframe at the current point of execution? Given a pointer to an object and it's type ... can I do std::vector getClassMember(class_name); ? I realize the default answer is "no, C++ doesn't support that level of introspection" -- however, recall I'm on linux, my program is compiled with "-g", and gdb can do it, so clearly the inforamtion is there. Question is: is there some API for accessing it? EDIT: PS Naysers, I'd love to see a reason for closing this question.

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• Multiple generic types in one container

  - by Lirik

  I was looking at the answer of this question regarding multiple generic types in one container and I can't really get it to work: the properties of the Metadata class are not visible, since the abstract class doesn't have them. Here is a slightly modified version of the code in the original question: public abstract class Metadata { } public class Metadata<T> : Metadata { // ... some other meta data public T Function{ get; set; } } List<Metadata> metadataObjects; metadataObjects.Add(new Metadata<Func<double,double>>()); metadataObjects.Add(new Metadata<Func<int,double>>()); metadataObjects.Add(new Metadata<Func<double,int>>()); foreach( Metadata md in metadataObjects) { var tmp = md.Function; // <-- Error: does not contain a definition for Function } The exact error is: error CS1061: 'Metadata' does not contain a definition for 'Function' and no extension method 'Function' accepting a first argument of type 'Metadata' could be found (are you missing a using directive or an assembly reference?) I believe it's because the abstract class does not define the property Function, thus the whole effort is completely useless. Is there a way that we can get the properties?

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• Performance Comparison of Shell Scripts vs high level interpreted langs (C#/Java/etc.)

  - by dferraro

  Hi all, First - This is not meant to be a 'which is better, ignorant nonionic war thread'... But rather, I generally need help in making an architecture decision / argument to put forward to my boss. Skipping the details - I simply just would love to know and find the results of anyone who has done some performance comparisons of Shell vs [Insert General Purpose Programming Language (interpreted) here), such as C# or Java... Surprisingly, I have spent some time on Google on searching here to not find any of this data. Has anyone ever done these comparisons, in different use-cases; hitting a database like in a XYX # of loops doing different types of SQL (Oracle pref, but MSSQL would do) queries such as any of the CRUD ops - and also not hitting database and just regular 50k loop type comparison doing different types of calculations, and things of that nature? In particular - for right now, I need to a comparison of hitting an Oracle DB from a shell script vs, lets say C# (again, any GPPL thats interpreted would be fine, even the higher level ones like Python). But I also need to know about standard programming calculations / instructions/etc... Before you ask 'why not just write a quick test yourself? The answer is: I've been a Windows developer my whole life/career and have very limited knowledge of Shell scripting - not to mention *nix as a whole.... So asking the question on here from the more experienced guys would be grealty beneficial, not to mention time saving as we are in near perputual deadline crunch as it is ;). Thanks so much in advance,

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• What does P mean in Sort(Expression<Func<T, P>> expr, ListSortDirection direction)?

  - by Grasshopper

  I am attempting to use the answer in post: How do you sort an EntitySet<T> to expose an interface so that I can sort an EntitySet with a Binding list. I have created the class below and I get the following compiler error: "The type or namespace 'P' could not be found (are you missing a using directive or assembly reference?). Can someone tell me what the P means and which namespace I need to include to get the method below to compile? I am very new to delegates and lamba expressions. Also, can someone confirm that if I create a BindingList from my EntitySet that any modifications I make to the BindingList will be made to the EntitySet? Basically, I have an EntitySet that I need to sort and make changes to. Then, I will need to persist these changes using the original Entity that the BindingList came from. public class EntitySetBindingWrapper<T> : BindingList<T> { public EntitySetBindingWrapper(BindingList<T> root) : base(root) { } public void Sort(Expression<Func<T, P>> expr, ListSortDirection direction) { if (expr == null) base.RemoveSortCore(); MemberExpression propExpr = expr as MemberExpression; if (propExpr == null) throw new ArgumentException("You must provide a property", "expr"); PropertyDescriptorCollection descriptorCol = TypeDescriptor.GetProperties(typeof(T)); IEnumerable<PropertyDescriptor> descriptors = descriptorCol.Cast<PropertyDescriptor>(); PropertyDescriptor descriptor = descriptors.First(pd => pd.Name == propExpr.Member.Name); base.ApplySortCore(descriptor, direction); } }

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• Dynamic Select boxes page load

  - by Chris

  Hello, I have a dynamic chained select box that I am attempting to show the value of on a page load. In my chained select box, it will default to the first option within the select box on page load, could anyone provide assitance? I stumbled upon this thread, but I can't seem to translate what they are doing with that answer to my language of CF. Dynamic chained drop downs on page refresh Here is the JS script I am using. function dynamicSelect(id1, id2) { // Feature test to see if there is enough W3C DOM support if (document.getElementById && document.getElementsByTagName) { // Obtain references to both select boxes var sel1 = document.getElementById(id1); var sel2 = document.getElementById(id2); // Clone the dynamic select box var clone = sel2.cloneNode(true); // Obtain references to all cloned options var clonedOptions = clone.getElementsByTagName("option"); // Onload init: call a generic function to display the related options in the dynamic select box refreshDynamicSelectOptions(sel1, sel2, clonedOptions); // Onchange of the main select box: call a generic function to display the related options in the dynamic select box sel1.onchange = function() { refreshDynamicSelectOptions(sel1, sel2, clonedOptions); } } } function refreshDynamicSelectOptions(sel1, sel2, clonedOptions) { // Delete all options of the dynamic select box while (sel2.options.length) { sel2.remove(0); } // Create regular expression objects for "select" and the value of the selected option of the main select box as class names var pattern1 = /( |^)(select)( |$)/; var pattern2 = new RegExp("( |^)(" + sel1.options[sel1.selectedIndex].value + ")( |$)"); // Iterate through all cloned options for (var i = 0; i < clonedOptions.length; i++) { // If the classname of a cloned option either equals "select" or equals the value of the selected option of the main select box if (clonedOptions[i].className.match(pattern1) || clonedOptions[i].className.match(pattern2)) { // Clone the option from the hidden option pool and append it to the dynamic select box sel2.appendChild(clonedOptions[i].cloneNode(true)); } } } Thanks so much for any assistance

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• Centered DIV w/ width dependant on text, buffered by two divs that should fill the containing DIV

  - by Andrew Thompson

  I have been wracking my brains on this seemingly small issue the whole day. My web dev friends are baffled and I could not find a suitable answer in my search of this site and others (though, I could have missed it somewhere along the way). Here's the problem: 3 DIVS within one fixed-width container DIV The center DIV has text that will be different on other sites The center DIV needs to be centered, and no larger than the text it contains. This is what I'd like to end up with The basic HTMl: <div id="container" > <div id="left" ></div> <div id="center" >Text inside center should resize this block</div> <div id="right" ></div> </div> Below, I removed most of the styles I have tried. This CSS currently centers the DIV (if I set it as an inline block), but I need the other divs to fill the left and right space remaining: #container { width:750px; text-align:center; } #left { background-color:#E85355; } #center { background-color:#CDD7D7; display:inline-block; } #right { background-color:#65A8A6; } I've tried floating, no-wrap, overflow, etc. Thanks a million to whomever can offer some help! JSFiddle Link

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• Android newbie installing Eclipse, having issues....

  - by Jeff

  I am a web developer, new to app development and Java/Android. I am about to follow some tutorials to get started learning but I'm running into a wall. The Android dev site says the recommended way to build Android apps is in Java using the Eclipse plug in. So I downloaded Eclipse Classic and unzipped it on to get this error: "A Java Runtime Environment (JRE) or Java Development Kit (JDK) must be available in order to run Eclipse. No Java virtual machine was found after searching the following locations: /Users//Desktop/eclipse/Eclipse.app/Contents/MacOS/jre/bin/java java in your current PATH" Any idea what the issue is and how I can fix it? Again, newbie to java, jre, android, so I apologize if this question has already been asked. In my research I've discovered that most of the posts or solutions I've found are tough for me to follow. There's always a few unclear items that are probably prohibiting me from getting the answer I need. So I'm hoping someone can walk me through installing or configuring whatever I need to regarding Java so I can continue installing Eclipse and begin learning. I should probably note that I'm on Mac OSX 10.6.6 Snow Leopard. Please let me know if you need any other info. Thanks so much in advance for any and all help!!!

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• Thread mutex behaviour

  - by Alberteddu

  Hi there, I'm learning C. I'm writing an application with multiple threads; I know that when a variable is shared between two or more threads, it is better to lock/unlock using a mutex to avoid deadlock and inconsistency of variables. This is very clear when I want to change or view one variable. int i = 0; /** Global */ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; /** Thread 1. */ pthread_mutex_lock(&mutex); i++; pthread_mutex_unlock(&mutex); /** Thread 2. */ pthread_mutex_lock(&mutex); i++; pthread_mutex_unlock(&mutex); This is correct, I think. The variable i, at the end of the executions, contains the integer 2. Anyway, there are some situations in which I don't know exactly where to put the two function calls. For example, suppose you have a function obtain(), which returns a global variable. I need to call that function from within the two threads. I have also two other threads that call the function set(), defined with a few arguments; this function will set the same global variable. The two functions are necessary when you need to do something before getting/setting the var. /** (0) */ /** Thread 1, or 2, or 3... */ if(obtain() == something) { if(obtain() == somethingElse) { // Do this, sometimes obtain() and sometimes set(random number) (1) } else { // Do that, just obtain(). (2) } } else { // Do this and do that (3) // If # of thread * 3 > 10, then set(3*10) For example. (4) } /** (5) */ Where I have to lock, and where I have to unlock? The situation can be, I think, even more complex. I will appreciate an exhaustive answer. Thank you in advance. —Alberto

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• PHP Object Access Syntax Question with the $

  - by ImperialLion

  I've been having trouble searching for this answer because I am not quite sure how to phrase it. I am new to PHP and still getting my feet on the ground. I was writing a page with a class in it that had the property name. When I originally wrote the page there was no class so I just had a variable called $name. When I went to encapsulate it in a class I accidental changed it to be $myClass->$name. It tool me a while to realize that the syntax I needed was $myClass->name. The reason it took so long was the error I kept getting was "Attempt to access a null property" or something along those lines. The error lead me to believe it was a data population error. My question is does $myClass->$name have a valid meaning? In other words is there a time you would use this and a reason why it doesn't create a syntax error? If so what is the semantic meaning of that code? When would I use it if it is valid? If its not valid, is there a reason that it doesn't create a syntax error?

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• First Time Architecturing?

  - by cam

  I was recently given the task of rebuilding an existing RIA. The new RIA that I've designed is based on Silverlight, with a WCF service to connect to MS SQL Server. This is my first time doing something like this, so I'm not sure how to design the entire thing. Basically, the client can look through graphs of "stocks" (allowing the client to choose different time periods, settings, etc). I've written the whole application essentially, but I'm not sure how to put it together. The graphs are supposed to be directly based on the database, and to create the datapoints on the graph, some calculations need to be done (not very expensive ones). The problem I'm having is to decide where to put the calculations (client or serverside? Or half and half?) What factors should I look for to help me decide where the calculations should be done? And how can I go about optimizing this (caching, etc)? Obviously this is a very broad subject, so I'm not expecting an immediate answer, but any help/pointing in the right direction/resources would be appreciated.

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• Centralizing Messagebox handling for application

  - by DRapp

  I'm wondering how others deal with trying to centralize MessageBox function calling. Instead of having long text embedded all over the place in code, in the past (non .net language), I would put system and application base "messagebox" type of messages into a database file which would be "burned" into the executable, much like a resource file in .Net. When a prompting condition would arise, I would just do call something like MBAnswer = MyApplication.CallMsgBox( IDUserCantDoThat ) then check the MBAnswer upon return, such as a yes/no/cancel or whatever. In the database table, I would have things like what the messagebox title would be, the buttons that would be shown, the actual message, a special flag that automatically tacked on a subsequent standard comment like "Please contact help desk if this happens.". The function would call the messagebox with all applicable settings and just return back the answer. The big benefits of this was, one location to have all the "context" of messages, and via constants, easier to read what message was going to be presented to the user. Does anyone have a similar system in .Net to do a similar approach, or is this just a bad idea in the .Net environment.

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• What's the correct place to share application logic in CakePHP?

  - by Pichan

  I guess simple answer to the question would be a component. Although I agree, I feel weird having to write a component for something so specific. For example, let's say I have a table of users. When a user is created, it should form a chain reaction of events, initiating different kinds of data related to the user all around the database. I figured it would be best to avoid directly manipulating the database from different controllers and instead pack all that neatly in a method. However since some logic needs to be accesed separately, I really can't have the whole package in a single method. Instead I thought it would be logical to break it up to smaller pieces(like $userModelOrController->createNew() and $candyStorageModelOrController->createNew()) that only interact with their respective database table. Now, if the logic is put to the model, it works great until I need to use other models. Of course it's possible, but when compared to loading models in a controller, it's not that simple. It's like a Cake developer telling me "Sure, it's possible if you want to do it that way but that's not how I would do it". Then, if the logic is put to the controller, I can access other models really easy through $this->loadModel(), but that brings me back to the previously explained situation since I need to be able to continue the chain reaction indefinitely. Accessing other controllers from a controller is possible, but again there doesn't seem to be any direct way of doing so, so I'm guessing I'm still not doing it right. By using a component this problem could be solved easily, since components are available to every controller I want. But like I wrote at the beginning, it feels awkward to create a component specifically for this one task. To me, components seem more like packages of extra functionality(like the core components) and not something to share controller-specific logic. Since I'm new to this whole MVC thing, I could've completely misunderstood the concept. Once again, I would be thankful if someone pointed me to the right direction :)

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• Is it getting to be time for C# to support compile-time macros?

  - by Robert Rossney

  Thus far, Microsoft's C# team has resisted adding formal compile-time macro capabilities to the language. There are aspects of programming with WPF that seem (to me, at least) to be creating some compelling use cases for macros. Dependency properties, for instance. It would be so nice to just be able to do something like this: [DependencyProperty] public string Foo { get; set; } and have the body of the Foo property and the static FooProperty property be generated automatically at compile time. Or, for another example an attribute like this: [NotifyPropertyChanged] public string Foo { get; set; } that would make the currently-nonexistent preprocessor produce this: private string _Foo; public string Foo { get { return _Foo; } set { _Foo = value; OnPropertyChanged("Foo"); } } You can implement change notification with PostSharp, and really, maybe PostSharp is a better answer to the question. I really don't know. Assuming that you've thought about this more than I have, which if you've thought about it at all you probably have, what do you think? (This is clearly a community wiki question and I've marked it accordingly.)

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