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• Click behaviour - Difference in IE and FF ?!

  - by OlliD

  Hey folks, i just came to the conclusion that a project i am currently working on might have a "logical" error in functionality. Currently I'am using server technology with PHP/MySQL and JQuery. Within the page there's a normal link reference with tag <a href="contentpage?page=xxx">next step</a> The pain point now seems to be the given jquery click event on the same element. The intension was to save the (current) content of the page (- form elements) via another php script using the php session command. For any reason, IE can handle the click event of Jquery right before executing the standard html command, that reloads the current page again with the new page parameter. By using FF the behaviour is different. I assume, that FF first execute the html command and afterwards execute the javascript code which handles the click event. Therefore the resultset here is wrong respectivly empty. My question now is whether you made the same experience and how you handled / wordarrounded this problem. I'd be thankful fur any of your tips or further feedback. Maybe you also have a solution on how to rethink about the current architecture. Regards, Oliver

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• string s; &s+1; Legal? UB?

  - by John Dibling

  Consider the following code: #include <cstdlib> #include <iostream> #include <string> #include <vector> #include <algorithm> using namespace std; int main() { string myAry[] = { "Mary", "had", "a", "Little", "Lamb" }; const size_t numStrs = sizeof(myStr)/sizeof(myAry[0]); vector<string> myVec(&myAry[0], &myAry[numStrs]); copy( myVec.begin(), myVec.end(), ostream_iterator<string>(cout, " ")); return 0; } Of interest here is &myAry[numStrs]: numStrs is equal to 5, so &myAry[numStrs] points to something that doesn't exist; the sixth element in the array. There is another example of this in the above code: myVec.end(), which points to one-past-the-end of the vector myVec. It's perfecly legal to take the address of this element that doesn't exist. We know the size of string, so we know where the address of the 6th element of a C-style array of strings must point to. So long as we only evaluate this pointer and never dereference it, we're fine. We can even compare it to other pointers for equality. The STL does this all the time in algorithms that act on a range of iterators. The end() iterator points past the end, and the loops keep looping while a counter != end(). So now consider this: #include <cstdlib> #include <iostream> #include <string> #include <vector> #include <algorithm> using namespace std; int main() { string myStr = "Mary"; string* myPtr = &myStr; vector<string> myVec2(myPtr, &myPtr[1]); copy( myVec2.begin(), myVec2.end(), ostream_iterator<string>(cout, " ")); return 0; } Is this code legal and well-defined? It is legal and well-defined to take the address of an array element past the end, as in &myAry[numStrs], so should it be legal and well-defined to pretend that myPtr is also an array?

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• AIX specific socket programming query

  - by kumar_m_kiran

  Hi All, Question 1 From SUSE man pages, I get the below details for socket connect options If the initiating socket is connection-mode, then connect() shall attempt to establish a connection to the address specified by the address argument. If the connection cannot be established immediately and O_NONBLOCK is not set for the file descriptor for the socket, connect() shall block for up to an unspecified timeout interval until the connection is established. If the timeout interval expires before the connection is established, connect() shall fail and the connection attempt shall be aborted. If connect() is interrupted by a signal that is caught while blocked waiting to establish a connection, connect() shall fail and set errno to [EINTR], but the connection request shall not be aborted, and the connection shall be established asynchronously. Question : Is the above contents valid for AIX OS (especially the connection time-out, timed wait ...etc)?Because I do not see it in AIX man pages (5.1 and 5.3) Question 2 I have a client socket whose attributes are a. SO_RCVTIMEO ,SO_SNDTIMEO are set for 5 seconds. b. AF_INET and SOCK_STREAM. c. SO_LINGER with linger on and time is 5 seconds. d. SO_REUSEADDR is set. Note that the client socket is not O_NONBLOCK. Question : Now since O_NONBLOCK is not set and SO_RCVTIMEO and SO_SNDTIMEO is set for 5 seconds, does it mean a. connect in NON Blocking or Blocking? b. If blocking, is it timed blocking or "infinite" time blocking? c. If it is infinite, How do I establish a "connect" system call which is O_BLOCKING with timeout to t secs. Sorry if the questions are be very naive. Thanks in advance for your input.

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• Undefined behaviour with non-virtual destructors - is it a real-world issue?

  - by Roddy

  Consider the following code: class A { public: A() {} ~A() {} }; class B: public A { B() {} ~B() {} }; A* b = new B; delete b; // undefined behaviour My understanding is that the C++ standard says that deleting b is undefined behaviour - ie, anything could happen. But, in the real world, my experience is that ~A() is always invoked, and the memory is correctly freed. if B introduces any class members with their own destructors, they won't get invoked, but I'm only interested in the simple kind of case above, where inheritance is used maybe to fix a bug in one class method for which source code is unavailable. Obviously this isn't going to be what you want in non-trivial cases, but it is at least consistent. Are you aware of any C++ implementation where the above does NOT happen, for the code shown?

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• Is a safe accumulator really this complicated?

  - by Martin

  I'm trying to write an accumulator that is well behaved given unconstrained inputs. This seems to not be trivial and requires some pretty strict planning. Is it really this hard? int naive_accumulator(unsigned int max, unsigned int *accumulator, unsigned int amount) { if(*accumulator + amount >= max) return 1; // could overflow *accumulator += max; // could overflow return 0; } int safe_accumulator(unsigned int max, unsigned int *accumulator, unsigned int amount) { // if amount >= max, then certainly *accumulator + amount >= max if(amount >= max) { return 1; } // based on the comparison above, max - amount is defined // but *accumulator + amount might not be if(*accumulator >= max - amount) { return 1; } // based on the comparison above, *accumulator + amount is defined // and *accumulator + amount < max *accumulator += amount; return 0; }

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• Is Behaviour supported on wpf in 3.5? I cannot see System.Windows.Interactivity in VS2010

  - by Rohit

  Is Behaviour supported on wpf in 3.5? I cannot see System.Windows.Interactivity in VS2010

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• Do views only perform the joins that they need to, or all joins always?

  - by Nate

  I am on an oracle DB. Lets say I have one view that joins to three tables. The view has two fields each. Each field only needs data from two of the three tables. If I query the view and return only one field, does the view still join to three tables or just to the two tables that it needs to calculate the field?

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• Call a non member funcion on an instance before is constructed.

  - by Tom

  Hi everyone. I'm writing a class, and this doubt came up. Is this undef. behaviour? On the other hand, I'm not sure its recommended, or if its a good practice. Is it one if I ensure no exceptions to be thrown in the init function? //c.h class C{ float vx,vy; friend void init(C& c); public: C(); ~C(); }; //c.cpp C::C() { init(*this); } void init(C& c) //throws() to ensure no exceptions ? { c.vx = 0; c.vy = 0; } Thanks in advance

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• Call a non member function on an instance before is constructed.

  - by Tom

  Hi everyone. I'm writing a class, and this doubt came up. Is this undef. behaviour? On the other hand, I'm not sure its recommended, or if its a good practice. Is it one if I ensure no exceptions to be thrown in the init function? //c.h class C{ float vx,vy; friend void init(C& c); public: C(); }; //c.cpp C::C() { init(*this); } void init(C& c) //throws() to ensure no exceptions ? { c.vx = 0; c.vy = 0; } Thanks in advance

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• Is there a language or design pattern that allows the *removal* of object behavior or properties in a class hierarchy?

  - by Sebastien Diot

  A well-know shortcoming of traditional class hierarchies is that they are bad when it comes to model the real world. As an example, trying to represent animals species with classes. There are actually several problems when doing that, but one that I never saw a solution to is when a sub-class "looses" a behavior or properties that was defined in a super-class, like a penguin not being able to fly (there are probably better examples, but that's the first one that comes to my mind, having seen "Madagascar 2" recently). On the one hand, you don't want to define for every property and behavior some flag that specifies if it is at all present, and check it every time before accessing that behavior or property. You would just like to say that birds can fly, simply and clearly, in the Bird class. But then it would be nice if one could define "exceptions" afterward, without having to use some horrible hacks everywhere. This often happens when a system has been productive for a while. You suddenly find an "exception" that doesn't fit in the original design at all, and you don't want to change a large portion of your code to accommodate it. So, is there some language or design patterns that can cleanly handle this problem, without requiring major changes to the "super-class", and all the code that uses it? Even if a solution only handle a specific case, several solutions might together form a complete strategy. [EDIT] Forgot about the Liskov Substitution Principle. That is why you can't do it. Assuming you define "traits/interfaces" for all major "feature groups", you can freely implement traits in different branches of the hierarchy, like the Flying trait could be implemented by Birds, and some special kind of squirrels and fish. So my question could amount to "How could I un-implement a trait?" If your super-class is a Java Serializable, you have to be one too, even if there is no way for you to serialize your state, for example if you contained a "Socket". So one way to do it is to always define all your traits in pair from the start: Flying and NotFlying (which would throw UnsupportedOperationExceiption, if not checked against). The Not-trait would not define any new interface, and could be simply checked for. Sounds like a "cheap" solution, in particular if used from the start.

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• What are best practices for testing programs with stochastic behavior?

  - by John Doucette

  Doing R&D work, I often find myself writing programs that have some large degree of randomness in their behavior. For example, when I work in Genetic Programming, I often write programs that generate and execute arbitrary random source code. A problem with testing such code is that bugs are often intermittent and can be very hard to reproduce. This goes beyond just setting a random seed to the same value and starting execution over. For instance, code might read a message from the kernal ring buffer, and then make conditional jumps on the message contents. Naturally, the ring buffer's state will have changed when one later attempts to reproduce the issue. Even though this behavior is a feature it can trigger other code in unexpected ways, and thus often reveals bugs that unit tests (or human testers) don't find. Are there established best practices for testing systems of this sort? If so, some references would be very helpful. If not, any other suggestions are welcome!

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• Should interface only be used for behavior and not to show logical data grouped together?

  - by jags

  Should an interface only be used to specify certain behavior? Would it be wrong to use interface to group logically related data? To me it looks like we should not use interface to group logically related data as structure seems a better fit. A class may be used but class name should indicate something like DTO so that user gets the impression that class does not have any behavior. Please let me know if my assumption is correct. Also, are there any exceptions where interface can be used to group logically related data?

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• What XMonad Configuration Best Replicates Default Ion3 Behavior and Feature Set?

  - by mtp

  Not being very familiar with Haskell and lamenting that Ion 3 is now abandonware, I am curious if anyone out there has found a way of replicating the default Ion 3 behavior and aesthetics in XMonad. If I can't have a near-exact replica of Ion 3-style behavior in XMonad, here is what would be critical to me: Virtual desktops that are empty by default and that spawn full-screen applications, which can be split horizontally or vertically evenly, leaving an empty adjacent pane. The panes, which house open windows, are manually resizable, preferably via keyboard. The panes exhibit tabbed behavior, meaning that they can house multiple windows. Windows can be tagged and moved between panes / virtual desktops via keyboard sequence. A given window may be temporarily exploded into full-screen mode via keyboard sequence. Each new virtual desktop starts in the same state—i.e., with one pane. Each virtual desktop may have its panes divided independently of other virtual desktops. From my investigation, it appears that there are several configurations that provide #3. For as much as I want to spend the time to familiarize myself with Haskell, I just simply don't have time. Any suggestions would be greatly appreciated. As far as I can tell, Ion has no conception of master pane or window, so this behavior is not desired.

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• Warehouse Management per Endeca: disponibili i video su Youtube

  - by Claudia Caramelli-Oracle

  12.00 Il team di gestione del prodotto WMS ha registrato quattro video sulle estensioni Warehouse Management per Endeca – il programma che gestisce in tempo reale le operazioni di magazzino. Quasi un'ora di contenuti che copre: Introduzione alle estensioni WMS per Endeca Plan and Track Fulfillment Space Utilization Labor Utilization Tutti e quattro i video possono essere trovati cliccando qui. v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} 12.00 Normal 0 14 false false false IT X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} 12.00 Normal 0 14 false false false IT X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} 12.00 Normal 0 14 false false false IT X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} Normal 0 14 false false false IT X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";}

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• A more reliable and more flexible sp_MSforeachdb

  - by AaronBertrand

  I've complained about sp_MSforeachdb before. In part of my "Bad Habits to Kick" series in 2009-10, I described how I worked around its sporadic inability to actually process all of the databases on an instance: http://sqlblog.com/blogs/aaron_bertrand/archive/2010/02/08/bad-habits-to-kick-relying-on-undocumented-behavior.aspx I lumped this in a "Bad Habit" category of relying on undocumented behavior, since - while the procedure does have rampant usage - it is, in fact, both undocumented and unsupported....(read more)

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• Is there a language where collections can be used as objects without altering the behavior?

  - by Dokkat

  Is there a language where collections can be used as objects without altering the behavior? As an example, first, imagine those functions work: function capitalize(str) //suppose this *modifies* a string object capitalizing it function greet(person): print("Hello, " + person) capitalize("pedro") >> "Pedro" greet("Pedro") >> "Hello, Pedro" Now, suppose we define a standard collection with some strings: people = ["ed","steve","john"] Then, this will call toUpper() on each object on that list people.toUpper() >> ["Ed","Steve","John"] And this will call greet once for EACH people on the list, instead of sending the list as argument greet(people) >> "Hello, Ed" >> "Hello, Steve" >> "Hello, John"

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• Issues with the intended behavior of a Service layer?

  - by Rafael Cichocki

  This analysis makes sense, and states anything that avoids code duplication and simplifies maintenance speaks for a service layer. What is the technical behavior? When a service client references a service, does it do so at runtime, or does it happen at compile time? When I change something in the service layer code, will this change be automatically taken into account in all it's clients, or do they need to be individually recompiled? How does this make sense from a testing point of view - I have working code, based on some code from a service, but if that service changes, my code might break?!

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• Reassessment: What's a good analytics package to use for tracking user behavior in a native iOS app?

  - by BeachRunnerJoe

  Hello. I've been poking around google and SO for answers on this, but it doesn't seem to be very well discussed, so I thought I revisit the question. Is anyone using any analytics packages (like Google Analytics or Mixpanel) to track user behavior in their native iOS apps? The three I've come across are Flurry, Mixpanel, and Google Analytics. It sounds like Apple is still peeved at Flurry, so I don't want to mess with that. Mixpanel looks simple and easy to use, but I'd first like to hear from someone who has used it. Same goes with Google Analytics for the iPhone. I've just finished building an iPhone game and I'd like to begin tweaking it based on how the users are playing it. Does anyone have any recommendations or experience with any of these analytics packages? Thanks so much!

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• How do I revert Alt-tab behavior to switch between windows on the current workspace?

  - by chris.ritsen

  Enabling Bias alt-tab sorting to prefer windows on the current viewport as described here made no difference. How can I get back the exact same behavior as 11.04, so that alt-tab only switches between windows on the current workspace? Simply disabling the alt-tab and shift-alt-tab keybindings on the unity switcher seems to have helped, but it still switches workspaces on me sometimes. For example, if I give a terminal window focus then press alt-tab, it switches to another terminal window on any workspace before trying to switch on the same workspace. Also, the Unity switcher still shows up when I alt-tab then hold alt even though I removed its alt-tab keybinding.

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• Is it possible to have an app in the Play Store that will modify/change the behavior of the Gmail for Android application?

  - by Benjamin Bakhshi

  For example, is it possible for Rapportive (which works on Gmail for web), to work on Gmail for Android. I understand that the UI would be vastly different, but the question remains, is it possible at all to overlay content or change behavior of the Gmail app for android. I have done some research but cannot find the right resources that would tell me if this is possible or not on Android devices. This is a trivial question for Gmail for Web, ie. making a Chrome extension has lots of resources, and services like Rapportive manipulate Gmail apparent ease.

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• Using mocks to set up object even if you will not be mocking any behavior or verifying any interaction with it?

  - by smp7d

  When building a unit test, is it appropriate to use a mocking tool to assist you in setting up an object even if you will not be mocking any behavior or verifying any interaction with that object? Here is a simple example in pseudo-code: //an object we actually want to mock Object someMockedObject = Mock(Object.class); EqualityChecker checker = new EqualityChecker(someMockedObject); //an object we are mocking only to avoid figuring out how to instantiate or //tying ourselves to some constructor that may be removed in the future ComplicatedObject someObjectThatIsHardToInstantiate = Mock(ComplicatedObject.class); //set the expectation on the mock When(someMockedObject).equals(someObjectThatIsHardToInstantiate).return(false); Assert(equalityChecker.check(someObjectThatIsHardToInstantiate)).isFalse(); //verify that the mock was interacted with properly Verify(someMockedObject).equals(someObjectThatIsHardToInstantiate).oneTime(); Is it appropriate to mock ComplicatedObject in this scenario?

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• Getting WCF Bindings and Behaviors from any config source

  - by cibrax

  The need of loading WCF bindings or behaviors from different sources such as files in a disk or databases is a common requirement when dealing with configuration either on the client side or the service side. The traditional way to accomplish this in WCF is loading everything from the standard configuration section (serviceModel section) or creating all the bindings and behaviors by hand in code. However, there is a solution in the middle that becomes handy when more flexibility is needed. This solution involves getting the configuration from any place, and use that configuration to automatically configure any existing binding or behavior instance created with code.  In order to configure a binding instance (System.ServiceModel.Channels.Binding) that you later inject in any endpoint on the client channel or the service host, you first need to get a binding configuration section from any configuration file (you can generate a temp file on the fly if you are using any other source for storing the configuration).  private BindingsSection GetBindingsSection(string path) { System.Configuration.Configuration config = System.Configuration.ConfigurationManager.OpenMappedExeConfiguration( new System.Configuration.ExeConfigurationFileMap() { ExeConfigFilename = path }, System.Configuration.ConfigurationUserLevel.None); var serviceModel = ServiceModelSectionGroup.GetSectionGroup(config); return serviceModel.Bindings; }   The BindingsSection contains a list of all the configured bindings in the serviceModel configuration section, so you can iterate through all the configured binding that get the one you need (You don’t need to have a complete serviceModel section, a section with the bindings only works).  public Binding ResolveBinding(string name) { BindingsSection section = GetBindingsSection(path); foreach (var bindingCollection in section.BindingCollections) { if (bindingCollection.ConfiguredBindings.Count > 0 && bindingCollection.ConfiguredBindings[0].Name == name) { var bindingElement = bindingCollection.ConfiguredBindings[0]; var binding = (Binding)Activator.CreateInstance(bindingCollection.BindingType); binding.Name = bindingElement.Name; bindingElement.ApplyConfiguration(binding); return binding; } } return null; }   The code above does just that, and also instantiates and configures the Binding object (System.ServiceModel.Channels.Binding) you are looking for. As you can see, the binding configuration element contains a method “ApplyConfiguration” that receives the binding instance that needs to be configured. A similar thing can be done for instance with the “Endpoint” behaviors. You first get the BehaviorsSection, and then, the behavior you want to use.  private BehaviorsSection GetBehaviorsSection(string path) { System.Configuration.Configuration config = System.Configuration.ConfigurationManager.OpenMappedExeConfiguration( new System.Configuration.ExeConfigurationFileMap() { ExeConfigFilename = path }, System.Configuration.ConfigurationUserLevel.None); var serviceModel = ServiceModelSectionGroup.GetSectionGroup(config); return serviceModel.Behaviors; }public List<IEndpointBehavior> ResolveEndpointBehavior(string name) { BehaviorsSection section = GetBehaviorsSection(path); List<IEndpointBehavior> endpointBehaviors = new List<IEndpointBehavior>(); if (section.EndpointBehaviors.Count > 0 && section.EndpointBehaviors[0].Name == name) { var behaviorCollectionElement = section.EndpointBehaviors[0]; foreach (BehaviorExtensionElement behaviorExtension in behaviorCollectionElement) { object extension = behaviorExtension.GetType().InvokeMember("CreateBehavior", BindingFlags.InvokeMethod | BindingFlags.NonPublic | BindingFlags.Instance, null, behaviorExtension, null); endpointBehaviors.Add((IEndpointBehavior)extension); } return endpointBehaviors; } return null; }   In this case, the code for creating the behavior instance is more tricky. First of all, a behavior in the configuration section actually represents a set of “IEndpoint” behaviors, and the behavior element you get from the configuration does not have any public method to configure an existing behavior instance. This last one only contains a protected method “CreateBehavior” that you can use for that purpose. Once you get this code implemented, a client channel can be easily configured as follows  var binding = resolver.ResolveBinding("MyBinding"); var behaviors = resolver.ResolveEndpointBehavior("MyBehavior"); SampleServiceClient client = new SampleServiceClient(binding, new EndpointAddress(new Uri("http://localhost:13749/SampleService.svc"), new DnsEndpointIdentity("localhost"))); foreach (var behavior in behaviors) { if(client.Endpoint.Behaviors.Contains(behavior.GetType())) { client.Endpoint.Behaviors.Remove(behavior.GetType()); } client.Endpoint.Behaviors.Add(behavior); }   The code above assumes that a configuration file (in any place) with a binding “MyBinding” and a behavior “MyBehavior” exists. That file can look like this,  <system.serviceModel> <bindings> <basicHttpBinding> <binding name="MyBinding"> <security mode="Transport"></security> </binding> </basicHttpBinding> </bindings> <behaviors> <endpointBehaviors> <behavior name="MyBehavior"> <clientCredentials> <windows/> </clientCredentials> </behavior> </endpointBehaviors> </behaviors> </system.serviceModel>   The same thing can be done of course in the service host if you want to manually configure the bindings and behaviors.  

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• Obstacle Avoidance steering behavior: how can an entity avoid an obstacle while other forces are acting on the entity?

  - by Prog

  I'm trying to implement the Obstacle Avoidance steering behavior in my 2D game. Currently my approach is to apply a force on the entity, in the direction of the normal of the heading, scaled by a number that gets bigger the closer we are to the obstacle. This is supposed to push the entity to the side and avoid the obstacle that blocks it's way. However, in the same time that my entity tries to avoid an obstacle, it Seeks to a point more or less behind the obstacle (which is the reason it needs to avoid the obstacle in the first place). The Seek algorithm constantly applies a force on the entity that pushes it (more or less) in the direction of the obstacle, while the Obstacle Avoidance algorithm constantly applies a force that pushes the entity away (more accurately, to the side) of the obstacle. The result is that sometimes the entity succesfully avoids the obstacle, and sometimes it collides with it, depending on the strength of the avoidance force I'm applying. How can I make sure that a force will succeed in steering the entity in some direction, while other forces are currently acting on the entity? (And while still looking natural). I can't allow entities to collide with obstacles when realistically they should be able to easily avoid them, doesn't matter what they're currently doing. Also, the Obstacle Avoidance algorithm is made exactly for the case where another force is acting on the entity. Otherwise it wouldn't be moving and there would be no need to avoid anything. So maybe I'm missing something. Thanks

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• How can I get cross-browser consistent behavior for TR heights within a table with a set height? [migrated]

  - by Dan

  I have an arbitrary number of tables with an arbitrary number of rows in each, and all tables are the same height. My initial approach was to just set the overall height of the table and hope the rows were smart enough to distribute themselves appropriately. That's not the case. I have 4 different behaviors going on with 4 browsers, but I need them to all render at the very least in a similar way. Safari & Chrome (WebKit): All rows are equal height, creating scroll bars as needed and fitting within table height. Firefox: All rows are the height necessary to fit their content, with the remaining rows overflowing out of the table. Additionally, If the content of the rows does not take up all of the height, only the part of the table with content in it takes the background (though it seems, through use of Firebug, that the actual table [and TR] extend to the bottom of the proper table height). IE: All rows are the height necessary to fit their content, with the remaining rows overflowing out of the table. Obviously this only includes one version of each browser and additional variation would likely appear with more being tested. Ideally, a solution where the browser renders TRs with less content smaller than those with larger content, while still using scrolling within the variable height TRs when the overall height of the table is not enough would be optimum. I could potentially see a solution to achieve that with JS, but can it be done with CSS? Or, if not, can the behavior that WebKit displays be made to work across the browsers? Thanks! PS: Example can be found here.

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• How to implement behavior in a component-based game architecture?

  - by ghostonline

  I am starting to implement player and enemy AI in a game, but I am confused about how to best implement this in a component-based game architecture. Say I have a following player character that can be stationary, running and swinging a sword. A player can transit to the swing sword state from both the stationary and running state, but then the swing must be completed before the player can resume standing or running around. During the swing, the player cannot walk around. As I see it, I have two implementation approaches: Create a single AI-component containing all player logic (either decoupled from the actual component or embedded as a PlayerAIComponent). I can easily how to enforce the state restrictions without creating coupling between individual components making up the player entity. However, the AI-component cannot be broken up. If I have, for example, an enemy that can only stand and walk around or only walks around and occasionally swing a sword, I have to create new AI-components. Break the behavior up in components, each identifying a specific state. I then get a StandComponent, WalkComponent and SwingComponent. To enforce the transition rules, I have to couple each component. SwingComponent must disable StandComponent and WalkComponent for the duration of the swing. When I have an enemy that only stands around, swinging a sword occasionally, I have to make sure SwingComponent only disables WalkComponent if it is present. Although this allows for better mix-and-matching components, it can lead to a maintainability nightmare as each time a dependency is added, the existing components must be updated to play nicely with the new requirements the dependency places on the character. The ideal situation would be that a designer can build new enemies/players by dragging components into a container, without having to touch a single line of engine or script code. Although I am not sure script coding can be avoided, I want to keep it as simple as possible. Summing it all up: Should I lob all AI logic into one component or break up each logic state into separate components to create entity variants more easily?

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