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  • New programming jargon you coined?

    - by jdk
    What programming terms have you coined that have taken off in your own circles? (i.e. have heard others repeating it?) It might be within your own team, workplace or garnered greater popularity on the Internet. Define your programming term, word or phrase in bold followed by an explanation, citation and/or usage example so we can use it in appropriate context. This question serves in the spirit of communication among programmers through sharing of terminology with each other, to benefit us by its propagation within our own teams and environments. Please no repeats of common jargon already ingrained in the programming culture like: "kludge", "automagically", "cruft", etc. (unless you coined it). Stealing from the comments: A shared vocabulary is the basis of communication, not just among programmers, Note: This Programming question has been reworded/reorganized to phrase a real question and remove ambiguity, vagueness and rhetorical device. It is not difficult to know what is being asked & question can be reasonably answered (see answers below).

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  • WPF, notify a child in the element tree about an event in a parent

    - by jester
    I am developing a WPF app and I want an event in a parent to be notified to several of its children in the element tree, so that each of them can take an action accordingly. I know that a custom RoutedEvent can be used to signal in the other direction from a child to one of its ancestors by bubbling the event upwards, so that any of the ancestor elements can handle the event. What I want is the children to be notified about an event in the parent and they handle them appropriately. What is the best strategy to achieve this? EDIT: Clarifying the comments : Say I have a parent UserControl. It has a TabControl and its contents are several nested child UserControls. Now consider a scenario where I want the TabControl.SelectionChanged() event to cause some changes in each of the child UserControl. How to achieve this? (The contents of each tab is a UserControl which themselves may contain another few levels of children UserControls. I want the UserControl in the bottom level to know about the SelectionChanged() event and respond accordingly).

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  • NHibernate listener/event to replace object before insert/update

    - by vIceBerg
    Hi! I have a Company class which have a collection of Address. Here's my Address class:(written top of my head): public class Address { public string Civic; public string Street; public City City; } This is the City class: public class City { public int Id; public string Name; public string SearchableName{ get { //code } } } Address is persisted in his own table and have a reference to the city's ID. City are also persisted in is own table. The City's SearchableName is used to prevent some mistakes in the city the user type. For example, if the city name is "Montréal", the searchable name will be "montreal". If the city name is "St. John", the searchable name will be "stjohn", etc. It's used mainly to to search and to prevent having multiple cities with a typo in it. When I save an address, I want an listener/event to check if the city is already in the database. If so, cancel the insert and replace the user's city with the database one. I would like the same behavior with updates. I tried this: public bool OnPreInsert(PreInsertEvent @event) { City entity = (@event.Entity as City); if (entity != null) { if (entity.Id == 0) { var city = (from c in @event.Session.Linq<City>() where c.SearchableName == entity.SearchableName select c).SingleOrDefault(); if (city != null) { //don't know what to do here return true; } } } return false; } But if there's already a City in the database, I don't know what to do. @event.Entity is readonly, if I set @event.Entity.Id, I get an "null identifier" exception. I tried to trap insert/update on Address and on Company, but the City if the first one to get inserted (it's logic...) Any thoughts? Thanks

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  • Excel automation: Close event missing

    - by chiccodoro
    Another hi all, I am doing Excel automation via Interop in C#, and I want to be informed when a workbook is closed. However, there is no Close event on the workbook nor a Quit event on the application. Has anybody done that before? How can I write a piece of code which reacts to the workbook being closed (which is only executed if the workbook is really closed)? Ideally that should happen after closing the workbook, so I can rely on the file to reflect all changes. Details about what I found so far: There is a BeforeClose() event, but if there are unsaved changes this event is raised before the user being asked whether to save them, so at the moment I can process the event, I don't have the final file and I cannot release the COM objects, both things that I need to have/do. I do not even know whether the workbook will actually be closed, since the user might choose to abort closing. Then there is a BeforeSave() event. So, if the user chooses "Yes" to save unsaved changes, then BeforeSave() is executed after BeforeClose(). However, if the user chooses to "Abort", then hits "file-save", the exact same order of events is executed. Further, if the user chooses "No", the BeforeSave() isn't executed at all. The same holds as long as the user doesn't click any of these options.

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  • .NET: How to pass value when subscribing to event and obtain it when the event is triggered (Dynamic

    - by Entrase
    The task is to create event handlers in runtime. I need the one method to be called with different parameter value for different events. The events and their number are only known in runtime. So I'm trying to generate dynamic methods, each of which will be assigned to some event, but in general they all just pass some value to an instance method and call it. It would be great if something similar could be done the easier way. I mean passing some value at subscribing stage and then obtaining it when the event is triggered. This is what I'm trying to do now: public class EventSource { public event EventHandler eventOne; public event EventHandler eventTwO; public event EventHandler eventThree; } public class EventListener { SubscribeForEvents() { BindingFlags flags = BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance; // Suppose we've already got EventInfo // and target source somewhere // so we can do eventInfo.AddEventHandler(target, delegate) // Now we need a delegate. int value = 42; Type tDelegate = eventInfo.EventHandlerType; // http://msdn.microsoft.com/en-us/library/ms228976(VS.95).aspx Type returnType = GetDelegateReturnType(tDelegate); DynamicMethod listener = new DynamicMethod("", null, GetDelegateParameterTypes(tDelegate), this.GetType()); ///////// Type[] callParameters = { typeof(int) }; MethodInfo method = this.GetType().GetMethod("ToCallFromDelegate", flags); ILGenerator generator = listener.GetILGenerator(); // No success in this mess. What's wrong? generator.Emit(OpCodes.Ldc_I4, value); generator.Emit(OpCodes.Call, method); generator.Emit(OpCodes.Pop); generator.Emit(OpCodes.Ret); ///////////// Delegate delegate = listener.CreateDelegate(tDelegate); eventInfo.AddEventHandler(target, delegate); // When triggered, there is InvalidProgramException } void ToCallFromDelegate(int value) { doSomething(); } }

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  • Assign click event to addon icon on navigation bar

    - by Charsee
    We have created a chrome extension for our app. Where we call a METHOD from a "js file" on CLICK event of the "extension icon" placed on the navigation bar. For this we use message passing between the app.js (file containing the METHOD to be called on icon click) and background.html (using a js file included in this html). The script used to pass message is:(from background.html) chrome.browserAction.onClicked.addListener(function (tab) { chrome.tabs.sendMessage(tab.id, "showPopup"); }); and to listen the message :(in app.js) chrome.extension.onMessage.addListener(function(request) { if (request === "showPopup") { showPopup(); } }); The click event works as expected. But now we want to do same thing in mozilla extension. and we can't pass message to app.js on the click of the icon,so that it can execute the containing methods. We have also added the app.js using pageMod, something like this exports.main = function(options, callbacks) { pageMod.PageMod({ include: ["*"], contentScriptWhen: 'start', contentScriptFile: [data.url('jquery-1.7.1.min.js'),data.url('app.js')] }); createAndAddNavBarButton(); }; function createAndAddNavBarButton() { var navBar = document.getElementById('nav-bar');//assume document has been defined if (!navBar){return;}; var nbBtn = document.createElement('navbaricon'); nbBtn.setAttribute('id', 'navButton'); nbBtn.setAttribute('image', data.url('icon_16.png')); nbBtn.onclick = function(){ showPopup(); return true; } navBar.appendChild(btn); } But the click event does nothing and showPopup() is undefined. When a new page loads event associated with it in the app.js executes without any error but the click event doesn't work. Is there a method from where we can assign click event directly to this icon, as we have done in the case of chrome extension.

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  • What is your favourite programming-related lolcat picture?

    - by DR
    In the spirit of these questions... http://stackoverflow.com/questions/234075/what-is-your-best-programmer-joke http://stackoverflow.com/questions/354686/programming-related-songs http://stackoverflow.com/questions/517897/anyone-know-any-programming-related-poetry ... I wonder: What is your favourite programming-related lolcat picture? Please add one answer per picture.

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  • Flash AS3: position loaded images from loop based on image height

    - by HeroicNate
    I'm trying to dynamically stack images that are being pulled in via an xml file. Below is what I'm doing, and it almost works. The problem is that it only seems to fire off the event complete function on the very last one, instead of going for all of them. Is there a way to make it run the even.complete function for each image? function aboutfileLoaded(event:Event):void { aboutXML = new XML(aboutTextLoader.data); for(var l:int = 0; l < aboutXML.aboutimages.image.length(); l++) { imageLoader = new Loader(); imageSource = aboutXML.aboutimages.image[l]; if (imageSource != "") { this.imageLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, aboutimageLoaded); this.imageLoader.load(new URLRequest(imageSource)); //aboutBox.aboutContent.addChild(imageLoader); //imageLoader.y = imageYpos; //imageYpos = imageYpos + 50; } } } function aboutimageLoaded(event:Event):void { aboutBox.aboutContent.addChild(imageLoader); this.imageLoader.y = imageYpos; imageYpos = imageYpos + this.imageLoader.height; }

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  • Managed WMI Event class is not an event class???

    - by galets
    I am using directions from here: http://msdn.microsoft.com/en-us/library/ms257351(VS.80).aspx to create a managed event class. Here's the code that I wrote: [ManagementEntity] [InstrumentationClass(InstrumentationType.Event)] public class MyEvent { [ManagementKey] public string ID { get; set; } [ManagementEnumerator] static public IEnumerable<MyEvent> EnumerateInstances() { var e = new MyEvent() { ID = "9A3C1B7E-8F3E-4C54-8030-B0169DE922C6" }; return new MyEvent[] { e }; } } class Program { static void Main(string[] args) { var thisAssembly = typeof(Program).Assembly; var wmi_installer = new AssemblyInstaller(thisAssembly, null); wmi_installer.Install(null); wmi_installer.Commit(null); InstrumentationManager.RegisterAssembly(thisAssembly); Console.Write("Press Enter..."); Console.ReadLine(); var e = new MyEvent() { ID = "A6144A9E-0667-415B-9903-220652AB7334" }; Instrumentation.Fire(e); Console.Write("Press Enter..."); Console.ReadLine(); wmi_installer.Uninstall(null); } } I can run a program, and it properly installs. Using wbemtest.exe I can browse to the event, and "show mof": [dynamic: ToInstance, provider("WmiTest, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null")] class MyEvent { [read, key] string ID; }; Notice, the class does not inherit from __ExtrinsicEvent, which is weird... I can also run select * from MyEvent, and get the result. Instrumentation.Fire() also returns no error. However, when I'm trying to subscribe to event using "Notification Query" option, I'm getting 0x80041059 Number: 0x80041059 Facility: WMI Description: Class is not an event class. What am I doing wrong, and is there a correct way to create managed WMI event?

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  • Embedded programming books

    - by Velho Kerho
    What embedded programming/design books would you suggest? With embedded I mean near to hardware programming in ASM and C/C++. I'm looking something related to best practices in embedded programming/design. Operation system could be Linux, Real Time Linux or any other RTOS.

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  • Is programming overrated?

    - by aengine
    [Subjective and intended to be a community wiki] I am sorry for such an offensive question: But here are my arguments Most of the progress in "computing" has came from non-programming sources. i.e. People invented faster microprocessors and better routers and novel memory devices. I dont think on average people are writting more efficient programs than those written 10 years ago. And the newer and popular languages are infact slower than C. though speed is one of the lesser criterias. Most of the progress came from novel paradigms. Web, Internet, Cloud computing and Social networking are novel paradigms and did not involve progress in programming as such. Heck even facebook was written in PHP and not some extreme language. Though it did face scalability issues (same with twitter) but i believe money and better programmers (who came in much later) took care of that. Thus ideating capability trumped programming capability/ Even things like Map-Reduce, Column oriented database and Probablistic algorithms (E.g. bloom filters) came from hardcore Algorithms research, rather than some programming convention. Thus my final point is why programming skill is so overstressed? To point a recent example about how only 10% of programmers can "write code" (binary search) without debugging. Isnt it a bit hypocritical, considering your real successs lies in coming up with better algorithm or a novel feature rather than getting right first time???

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  • GNU/Emacs for gtk+ programming

    - by sterh
    Hello, I want to start C/gtk+ programming in GNU/Emacs. Where can i find manual, how to configure GNU/Emacs for C and gtk+ programming. I want to make GNU/Emacs IDE for gtk+ programming Thank you.

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  • Recommendations for technical (programming) podcasts or audio books?

    - by David Pfeffer
    I'd like to do some professional development during my commute, but I find that reading programming texts on the bus and train cause nausia because of how much I have to focus on them. I'd like to find some good technical programming audio books, either free or for purchase/download and some good technical podcasts. What are the best programming audio books or podcasts out there, and where can they be found?

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  • Asp.net or flash programming please help

    - by hugasuga
    Hi friends I am new to Programming.During last year I learned flash programming as well as Asp.net I am good at both. But i am confused about choosing asp.net or flash programming As per career which one will get me good salary and which one will me more secure Please help me on this with reasoning which one i should choose

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  • jQuery: Triggering a click on an img not working

    - by Twecs
    I'm testing in Chrome. I have a bunch of 'add item' icons on screen that the user can click in order to add that one item to the database. I also have a button at the botton of that list, which should add the whole list of items. It seems to me that the easiest way to do this is to trigger the 'click' event for all these icons (the reason I'm doing it via the icons is that items-specific values are stored as attributes of the div in which the icon resides). However, I can't get it to work: the event handlers for the individual icons work perfectly, and the event handler for the add-them-all button does give me an alert if I put that in. But if I add the I read some posts that suggest browsers don't allow you to trigger click events, so I added a 'hover' event listener to the icons to see if the problem is in the type of event I want to trigger. Answer: no, same story: the alert will work, but the trigger won't. I have placed the icon event listener in the code before the button event listener. What's going on? Twecs

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  • Problems to make programming more interesting for school students [closed]

    - by Jomoos
    I have to teach Java programming to school students and all are around the age of 15. None of them had any previous experience in programming. That is, I have to start from the very basics. I do like to make the sessions more interesting, and to make them love programming. I do need simple problems or puzzles -- not complex ones, simple ones -- that can increase their curiosity, and made them think and love programming. I do like to have problems for all of the concepts (like branching, looping, encapsulation, inheritance, composition, etc.,). Notes: I do have a time-frame of 1 hour for each session. Computers are not available. Maybe I can bring my laptop and show a demo to them. There are 7 students in the class.

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  • When my object is no longer referenced why do its events continue to run?

    - by Ryan Peschel
    Say I am making a game and have a base Buff class. I may also have a subclass named ThornsBuff which subscribes to the Player class's Damaged event. The Player may have a list of Buffs and one of them may be the ThornsBuff. For example: Test Class Player player = new Player(); player.ActiveBuffs.Add(new ThornsBuff(player)); ThornsBuff Class public ThornsBuff(Player player) { player.DamageTaken += player_DamageTaken; } private void player_DamageTaken(MessagePlayerDamaged m) { m.Assailant.Stats.Health -= (int)(m.DamageAmount * .25); } This is all to illustrate an example. If I were to remove the buff from the list, the event is not detached. Even though the player no longer has the buff, the event is still executed as if he did. Now, I could have a Dispel method to unregister the event, but that forces the developer to call Dispel in addition to removing the Buff from the list. What if they forget, increased coupling, etc. What I don't understand is why the event doesn't detatch itself automatically when the Buff is removed from the list. The Buff only existed in the list and that is its one reference. After it is removed shouldn't the event be detached? I tried adding the detaching code to the finalizer of the Buff but that didn't fix it either. The event is still running even after it has 0 references. I suppose it is because the garbage collector had not run yet? Is there any way to make it automatic and instant so that when the object has no references all its events are unregisted? Thanks.

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  • Design by Contract with Microsoft .Net Code Contract

    - by Fredrik N
    I have done some talks on different events and summits about Defensive Programming and Design by Contract, last time was at Cornerstone’s Developer Summit 2010. Next time will be at SweNug (Sweden .Net User Group). I decided to write a blog post about of some stuffs I was talking about. Users are a terrible thing! Protect your self from them ”Human users have a gift for doing the worst possible thing at the worst possible time.” – Michael T. Nygard, Release It! The kind of users Michael T. Nygard are talking about is the users of a system. We also have users that uses our code, the users I’m going to focus on is the users of our code. Me and you and another developers. “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” – Martin Fowler Good programmers also writes code that humans know how to use, good programmers also make sure software behave in a predictable manner despise inputs or user actions. Design by Contract   Design by Contract (DbC) is a way for us to make a contract between us (the code writer) and the users of our code. It’s about “If you give me this, I promise to give you this”. It’s not about business validations, that is something completely different that should be part of the domain model. DbC is to make sure the users of our code uses it in a correct way, and that we can rely on the contract and write code in a way where we know that the users will follow the contract. It will make it much easier for us to write code with a contract specified. Something like the following code is something we may see often: public void DoSomething(Object value) { value.DoIKnowThatICanDoThis(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Where “value” can be uses directly or passed to other methods and later be used. What some of us can easily forget here is that the “value” can be “null”. We will probably not passing a null value, but someone else that uses our code maybe will do it. I think most of you (including me) have passed “null” into a method because you don’t know if the argument need to be specified to a valid value etc. I bet most of you also have got the “Null reference exception”. Sometimes this “Null reference exception” can be hard and take time to fix, because we need to search among our code to see where the “null” value was passed in etc. Wouldn’t it be much better if we can as early as possible specify that the value can’t not be null, so the users of our code also know it when the users starts to use our code, and before run time execution of the code? This is where DbC comes into the picture. We can use DbC to specify what we need, and by doing so we can rely on the contract when we write our code. So the code above can actually use the DoIKnowThatICanDoThis() method on the value object without being worried that the “value” can be null. The contract between the users of the code and us writing the code, says that the “value” can’t be null.   Pre- and Postconditions   When working with DbC we are specifying pre- and postconditions.  Precondition is a condition that should be met before a query or command is executed. An example of a precondition is: “The Value argument of the method can’t be null”, and we make sure the “value” isn’t null before the method is called. Postcondition is a condition that should be met when a command or query is completed, a postcondition will make sure the result is correct. An example of a postconditon is “The method will return a list with at least 1 item”. Commands an Quires When using DbC, we need to know what a Command and a Query is, because some principles that can be good to follow are based on commands and queries. A Command is something that will not return anything, like the SQL’s CREATE, UPDATE and DELETE. There are two kinds of Commands when using DbC, the Creation commands (for example a Constructor), and Others. Others can for example be a Command to add a value to a list, remove or update a value etc. //Creation commands public Stack(int size) //Other commands public void Push(object value); public void Remove(); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   A Query, is something that will return something, for example an Attribute, Property or a Function, like the SQL’s SELECT.   There are two kinds of Queries, the Basic Queries  (Quires that aren’t based on another queries), and the Derived Queries, queries that is based on another queries. Here is an example of queries of a Stack: //Basic Queries public int Count; public object this[int index] { get; } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To understand about some principles that are good to follow when using DbC, we need to know about the Commands and different Queries. The 6 Principles When working with DbC, it’s advisable to follow some principles to make it easier to define and use contracts. The following DbC principles are: Separate commands and queries. Separate basic queries from derived queries. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries. For each command, write a postcondition that specifies the value of every basic query. For every query and command, decide on a suitable precondition. Write invariants to define unchanging properties of objects. Before I will write about each of them I want you to now that I’m going to use .Net 4.0 Code Contract. I will in the rest of the post uses a simple Stack (Yes I know, .Net already have a Stack class) to give you the basic understanding about using DbC. A Stack is a data structure where the first item in, will be the first item out. Here is a basic implementation of a Stack where not contract is specified yet: public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } //Is related to Count and this[] Query public object Top() { return this[Count]; } //Creation commands public Stack(uint size) { Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { this[++Count] = value; } public void Remove() { this[Count] = null; Count--; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The Stack is implemented in a way to demonstrate the use of Code Contract in a simple way, the implementation may not look like how you would implement it, so don’t think this is the perfect Stack implementation, only used for demonstration.   Before I will go deeper into the principles I will simply mention how we can use the .Net Code Contract. I mention before about pre- and postcondition, is about “Require” something and to “Ensure” something. When using Code Contract, we will use a static class called “Contract” and is located in he “System.Diagnostics.Contracts” namespace. The contract must be specified at the top or our member statement block. To specify a precondition with Code Contract we uses the Contract.Requires method, and to specify a postcondition, we uses the Contract.Ensure method. Here is an example where both a pre- and postcondition are used: public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The contract above requires that the Count is greater than 0, if not we can’t get the item at the Top of a Stack. We also Ensures that the results (By using the Contract.Result method, we can specify a postcondition that will check if the value returned from a method is correct) of the Top query is equal to this[Count].   1. Separate Commands and Queries   When working with DbC, it’s important to separate Command and Quires. A method should either be a command that performs an Action, or returning information to the caller, not both. By asking a question the answer shouldn’t be changed. The following is an example of a Command and a Query of a Stack: public void Push(object value) public object Top() .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The Push is a command and will not return anything, just add a value to the Stack, the Top is a query to get the item at the top of the stack.   2. Separate basic queries from derived queries There are two different kinds of queries,  the basic queries that doesn’t rely on another queries, and derived queries that uses a basic query. The “Separate basic queries from derived queries” principle is about about that derived queries can be specified in terms of basic queries. So this principles is more about recognizing that a query is a derived query or a basic query. It will then make is much easier to follow the other principles. The following code shows a basic query and a derived query: //Basic Queries public uint Count; //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   We can see that IsEmpty will use the Count query, and that makes the IsEmpty a Derived query.   3. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries.   When the derived query is recognize we can follow the 3ed principle. For each derived query, we can create a postcondition that specifies what result our derived query will return in terms of one or more basic queries. Remember that DbC is about contracts between the users of the code and us writing the code. So we can’t use demand that the users will pass in a valid value, we must also ensure that we will give the users what the users wants, when the user is following our contract. The IsEmpty query of the Stack will use a Count query and that will make the IsEmpty a Derived query, so we should now write a postcondition that specified what results will be returned, in terms of using a basic query and in this case the Count query, //Basic Queries public uint Count; //Derived Queries public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } The Contract.Ensures is used to create a postcondition. The above code will make sure that the results of the IsEmpty (by using the Contract.Result to get the result of the IsEmpty method) is correct, that will say that the IsEmpty will be either true or false based on Count is equal to 0 or not. The postcondition are using a basic query, so the IsEmpty is now following the 3ed principle. We also have another Derived Query, the Top query, it will also need a postcondition and it uses all basic queries. The Result of the Top method must be the same value as the this[] query returns. //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count and this[] Query public object Top() { Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   4. For each command, write a postcondition that specifies the value of every basic query.   For each command we will create a postconditon that specifies the value of basic queries. If we look at the Stack implementation we will have three Commands, one Creation command, the Constructor, and two others commands, Push and Remove. Those commands need a postcondition and they should include basic query to follow the 4th principle. //Creation commands public Stack(uint size) { Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   As you can see the Create command will Ensures that Count will be 0 when the Stack is created, when a Stack is created there shouldn’t be any items in the stack. The Push command will take a value and put it into the Stack, when an item is pushed into the Stack, the Count need to be increased to know the number of items added to the Stack, and we must also make sure the item is really added to the Stack. The postconditon of the Push method will make sure the that old value of the Count (by using the Contract.OldValue we can get the value a Query has before the method is called)  plus 1 will be equal to the Count query, this is the way we can ensure that the Push will increase the Count with one. We also make sure the this[] query will now contain the item we pushed into the Stack. The Remove method must make sure the Count is decreased by one when the top item is removed from the Stack. The Commands is now following the 4th principle, where each command now have a postcondition that used the value of basic queries. Note: The principle says every basic Query, the Remove only used one Query the Count, it’s because this command can’t use the this[] query because an item is removed, so the only way to make sure an item is removed is to just use the Count query, so the Remove will still follow the principle.   5. For every query and command, decide on a suitable precondition.   We have now focused only on postcondition, now time for some preconditons. The 5th principle is about deciding a suitable preconditon for every query and command. If we starts to look at one of our basic queries (will not go through all Queries and commands here, just some of them) the this[] query, we can’t pass an index that is lower then 1 (.Net arrays and list are zero based, but not the stack in this blog post ;)) and the index can’t be lesser than the number of items in the stack. So here we will need a preconditon. public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Think about the Contract as an documentation about how to use the code in a correct way, so if the contract could be specified elsewhere (not part of the method body), we could simply write “return _array[index]” and there is no need to check if index is greater or lesser than Count, because that is specified in a “contract”. The implementation of Code Contract, requires that the contract is specified in the code. As a developer I would rather have this contract elsewhere (Like Spec#) or implemented in a way Eiffel uses it as part of the language. Now when we have looked at one Query, we can also look at one command, the Remove command (You can see the whole implementation of the Stack at the end of this blog post, where precondition is added to more queries and commands then what I’m going to show in this section). We can only Remove an item if the Count is greater than 0. So we can write a precondition that will require that Count must be greater than 0. public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   6. Write invariants to define unchanging properties of objects.   The last principle is about making sure the object are feeling great! This is done by using invariants. When using Code Contract we can specify invariants by adding a method with the attribute ContractInvariantMethod, the method must be private or public and can only contains calls to Contract.Invariant. To make sure the Stack feels great, the Stack must have 0 or more items, the Count can’t never be a negative value to make sure each command and queries can be used of the Stack. Here is our invariant for the Stack object: [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The ObjectInvariant method will be called every time after a Query or Commands is called. Here is the full example using Code Contract:   public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } set { Contract.Requires(index >= 1); Contract.Requires(index <= Count); _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } //Is related to Count and this[] Query public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } //Creation commands public Stack(uint size) { Contract.Requires(size > 0); Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Requires(value != null); Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Summary By using Design By Contract we can make sure the users are using our code in a correct way, and we must also make sure the users will get the expected results when they uses our code. This can be done by specifying contracts. To make it easy to use Design By Contract, some principles may be good to follow like the separation of commands an queries. With .Net 4.0 we can use the Code Contract feature to specify contracts.

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  • Filtering Security Logs by User and Logon Type

    - by Trido
    I have been asked to find out when a user has logged on to the system in the last week. Now the audit logs in Windows should contain all the info I need. I think if I search for Event ID 4624 (Logon Success) with a specific AD user and Logon Type 2 (Interactive Logon) that it should give me the information I need, but for the life of my I cannot figure out how to actually filter the Event Log to get this information. Is it possible inside of the Event Viewer or do you need to use an external tool to parse it to this level? I found http://nerdsknowbest.blogspot.com.au/2013/03/filter-security-event-logs-by-user-in.html which seemed to be part of what I needed. I modified it slightly to only give me the last 7 days worth. Below is the XML I tried. <QueryList> <Query Id="0" Path="Security"> <Select Path="Security">*[System[(EventID=4624) and TimeCreated[timediff(@SystemTime) &lt;= 604800000]]]</Select> <Select Path="Security">*[EventData[Data[@Name='Logon Type']='2']]</Select> <Select Path="Security">*[EventData[Data[@Name='subjectUsername']='Domain\Username']]</Select> </Query> </QueryList> It only gave me the last 7 days, but the rest of it did not work. Can anyone assist me with this? EDIT Thanks to the suggestions of Lucky Luke I have been making progress. The below is my current query, although as I will explain it isn't returning any results. <QueryList> <Query Id="0" Path="Security"> <Select Path="Security"> *[System[(EventID='4624')] and System[TimeCreated[timediff(@SystemTime) &lt;= 604800000]] and EventData[Data[@Name='TargetUserName']='john.doe'] and EventData[Data[@Name='LogonType']='2'] ] </Select> </Query> </QueryList> As I mentioned, it wasn't returning any results so I have been messing with it a bit. I can get it to produce the results correctly until I add in the LogonType line. After that, it returns no results. Any idea why this might be? EDIT 2 I updated the LogonType line to the following: EventData[Data[@Name='LogonType'] and (Data='2' or Data='7')] This should capture Workstation Logons as well as Workstation Unlocks, but I still get nothing. I then modify it to search for other Logon Types like 3, or 8 which it finds plenty of. This leads me to believe that the query works correctly, but for some reason there are no entries in the Event Logs with Logon Type equalling 2 and this makes no sense to me. Is it possible to turn this off?

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  • Unwanted SDL_QUIT Event on mouseclick.

    - by Anthony Clever
    I'm having a slight problem with my SDL/Opengl code, specifically, when i try to do something on a mousebuttondown event, the program sends an sdl_quit event to the stack, closing my application. I know this because I can make the program work (sans the ability to quit out of it :| ) by checking for SDL_QUIT during my event loop, and making it do nothing, rather than quitting the application. If anyone could help make my program work, while retaining the ability to, well, close it, it'd be much appreciated. Code attached below: #include "SDL/SDL.h" #include "SDL/SDL_opengl.h" void draw_polygon(); void init(); int main(int argc, char *argv[]) { SDL_Event Event; int quit = 0; GLfloat color[] = { 0.0f, 0.0f, 0.0f }; init(); glColor3fv (color); glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0); draw_polygon(); while(!quit) { while(SDL_PollEvent( &Event )) { switch(Event.type) { case SDL_MOUSEBUTTONDOWN: for (int i = 0; i <= sizeof(color); i++) { color[i] += 0.1f; } glColor3fv ( color ); draw_polygon(); case SDL_KEYDOWN: switch(Event.key.keysym.sym) { case SDLK_ESCAPE: quit = 1; default: break; } default: break; } } } SDL_Quit(); return 0; } void draw_polygon() { glBegin(GL_POLYGON); glVertex3f (0.25, 0.25, 0.0); glVertex3f (0.75, 0.25, 0.0); glVertex3f (0.75, 0.75, 0.0); glVertex3f (0.25, 0.75, 0.0); glEnd(); SDL_GL_SwapBuffers(); } void init() { SDL_Init(SDL_INIT_EVERYTHING); SDL_SetVideoMode( 640, 480, 32, SDL_OPENGL ); glClearColor (0.0, 0.0, 0.0, 0.0); glMatrixMode( GL_PROJECTION | GL_MODELVIEW ); glLoadIdentity(); glClear (GL_COLOR_BUFFER_BIT); SDL_WM_SetCaption( "OpenGL Test", NULL ); } If it matters in this case, I'm compiling via the included compiler with Visual C++ 2008 express.

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  • Insert an event on Google Resource Calendar using the latest google-php-client-api

    - by user3781583
    Created a Project Enabled Calendar API Created an OAuth2.0 Service Account Downloaded the keyfile .p12 and saved it locally (not using a server with a public IP address) Shared my Resource Calendar with the Email address created in the Service Account (with Manage Sharing rights) Entered Client ID for the service account and authorized http://www.googleapis.com/auth/calendar Environment lamp setup on localhost. <?php require_once 'google-api-php-client/src/Google/Client.php'; require_once 'google-api-php-client/src/Google/Service/Calendar.php'; session_start(); const CLIENT_ID = 'XXXXXX.apps.googleusercontent.com'; //Service CLIENT ID const SERVICE_ACCOUNT_NAME = '[email protected]'; const KEY_FILE = 'google-api-php-client/src/Google/Reservation Service-XXXXXXX.p12'; $client = new Google_Client(); $client->setApplicationName("Appointment"); if (isset($_SESSION['token'])) { $client->setAccessToken($_SESSION['token']); } $key = file_get_contents(KEY_FILE); $client->setClientId(CLIENT_ID); $client->setAssertionCredentials(new Google_Auth_AssertionCredentials( SERVICE_ACCOUNT_NAME, array('https://www.googleapis.com/auth/calendar'), $key)); //Save token in session if ($client->getAccessToken()) { $_SESSION['token'] = $client->getAccessToken(); } $cal = new Google_Service_Calendar($client); $event = new Google_Service_Calendar_Event(); $event->setSummary('This is a Test event'); $event->setLocation('Test Location'); $start = new Google_Service_Calendar_EventDateTime(); $start->setDateTime('2014-08-20T10:30:00.000-05:00'); $event->setStart($start); $end = new Google_Service_Calendar_EventDateTime(); $end->setDateTime('2014-08-20T12:30:00.000-05:00'); $event->setEnd($end); $cal->events->insert('[email protected]', $event); ?> getting the following error: Fatal error: Uncaught exception 'Google_Service_Exception' with message 'Error calling POST https://www.googleapis.com/calendar/v3/calendars/XXXXXXX%40resource.calendar.google.com/events: (403) Forbidden' in /google-api-php-client/src/Google/Http/REST.php:79 Stack trace: #0 /google-api-php-client/src/Google/Http/REST.php(44): Google_Http_REST::decodeHttpResponse(Object(Google_Http_Request)) #1 /google-api-php-client/src/Google/Client.php(503): Google_Http_REST::execute(Object(Google_Client), Object(Google_Http_Request)) #2 /google-api-php-client/src/Google/Servic/Resource.php(195): Google_Client-execute(Object(Google_Http_Request)) #3 /google-api-php-client/src/Google/Service/Calendar.php(1459): Google_Service_Resource-call('insert', Array, 'Google_Service_...') #4 /calendar.php(53): Google_S in /google-api-php-client/src/Google/Http/REST.php on line 79 A few people had the same issue, I am sharing the calendar with the service account. Any help will be appreciated.

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