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  • How can I get VS2008 winforms designer to render a Form that implements an abstract base class

    - by BeowulfOF
    Hi, I engadged a problem with inherited Controls in WinForms, and need some advice on it. I do use a base class for items in a List (selfmade GUI list made of a panel) and some inherited controls that are for each type of data that could be added to the list. There was no problem with it, but I know found out, that it would be right, to make the base-control an abstract class, since it has methods, that need to be implemented in all inherited controls, called from the code inside the base-control, but must not and can not be implemented in the base class. When I mark the base-control as abstract, the VS2008 Designer refuses to load the window. Is there any way to get the Designer work with the base-control made abstract?

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  • How do you go from an abstract project description to actual code?

    - by Jason
    Maybe its because I've been coding around two semesters now, but the major stumbling block that I'm having at this point is converting the professor's project description and requirements to actual code. Since I'm currently in Algorithms 101, I basically do a bottom-up process, starting with a blank whiteboard and draw out the object and method interactions, then translate that into classes and code. But now the prof has tossed interfaces and abstract classes into the mix. Intellectually, I can recognize how they work, but am stubbing my toes figuring out how to use these new tools with the current project (simulating a web server). In my professors own words, mapping the abstract description to Java code is the real trick. So what steps are best used to go from English (or whatever your language is) to computer code? How do you decide where and when to create an interface, or use an abstract class?

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  • Getting set accessor for property in abstract class, not possible?

    - by Lars Udengaard
    Given the class': public abstract class AbstractEntity { public virtual Guid Id { get; private set; } } public class Entity { public virtual Guid Id { get; private set; } } And a PropertyInfo for the property 'Id'. When calling the method: PropertyInfo.GetAccessors() It returns both the get-method and the set-method when the class is not abstract (Entity), but only the get-method when the class is abstract (AbstractEntity). Why is this? And is there another way to get the set-method from a property with a private set?

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  • How to have abstract and overriding constants in C# ?

    - by Chris
    Hi all, My code below won't compile. What am i doing wrong? I'm basically trying to have a public constant that is overridden in the base class. public abstract class MyBaseClass { public abstract const string bank = "???"; } public class SomeBankClass : MyBaseClass { public override const string bank = "Some Bank"; } Thanks as always for being so helpful!

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  • How do I collect a bunch of Django abstract models in a QuerySet?

    - by Thierry Lam
    I have the following abstract Django models: class Food(models.Model): name = models.CharField(max_length=100) class Meta: abstract = True In one of my view, I created a bunch of Food model: panino = Food(name='Panino') poutine = Food(name='Poutine') food = [panino, poutine] From the above, I'm not saving the model and storing the Food model in a regular Python list. I want to store the above food models in a QuerySet object. How can I do that without storing any data to the database?

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  • What is there so useful in the Decorator Pattern? My example doesn't work

    - by Green
    The book says: The decorator pattern can be used to extend (decorate) the functionality of a certain object I have a rabbit animal. And I want my rabbit to have, for example, reptile skin. Just want to decorate a common rabbit with reptile skin. I have the code. First I have abstract class Animal with everythig that is common to any animal: abstract class Animal { abstract public function setSleep($hours); abstract public function setEat($food); abstract public function getSkinType(); /* and more methods which for sure will be implemented in any concrete animal */ } I create class for my rabbit: class Rabbit extends Animal { private $rest; private $stomach; private $skinType = "hair"; public function setSleep($hours) { $this->rest = $hours; } public function setFood($food) { $this->stomach = $food; } public function getSkinType() { return $this->$skinType; } } Up to now everything is OK. Then I create abstract AnimalDecorator class which extends Animal: abstract class AnimalDecorator extends Animal { protected $animal; public function __construct(Animal $animal) { $this->animal = $animal; } } And here the problem comes. Pay attention that AnimalDecorator also gets all the abstract methods from the Animal class (in this example just two but in real can have many more). Then I create concrete ReptileSkinDecorator class which extends AnimalDecorator. It also has those the same two abstract methods from Animal: class ReptileSkinDecorator extends AnimalDecorator { public function getSkinColor() { $skin = $this->animal->getSkinType(); $skin = "reptile"; return $skin; } } And finaly I want to decorate my rabbit with reptile skin: $reptileSkinRabbit = ReptileSkinDecorator(new Rabbit()); But I can't do this because I have two abstract methods in ReptileSkinDecorator class. They are: abstract public function setSleep($hours); abstract public function setEat($food); So, instead of just re-decorating only skin I also have to re-decorate setSleep() and setEat(); methods. But I don't need to. In all the book examples there is always ONLY ONE abstract method in Animal class. And of course it works then. But here I just made very simple real life example and tried to use the Decorator pattern and it doesn't work without implementing those abstract methods in ReptileSkinDecorator class. It means that if I want to use my example I have to create a brand new rabbit and implement for it its own setSleep() and setEat() methods. OK, let it be. But then this brand new rabbit has the instance of commont Rabbit I passed to ReptileSkinDecorator: $reptileSkinRabbit = ReptileSkinDecorator(new Rabbit()); I have one common rabbit instance with its own methods in the reptileSkinRabbit instance which in its turn has its own reptileSkinRabbit methods. I have rabbit in rabbit. But I think I don't have to have such possibility. I don't understand the Decarator pattern right way. Kindly ask you to point on any mistakes in my example, in my understanding of this pattern. Thank you.

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  • can't query from dbpedia with a sparql

    - by austin powers
    I want to query from dbpedia using their sparql interface (http://dbpedia.org/sparql) I want to get the abstract of http://dbpedia.org/page/Herbie_Mann I know that I have to call abstract ontology http://dbpedia.org/ontology/abstract and my final sparsql query is like following : SELECT ?abstract WHERE { { <http://dbpedia.org/page/Herbie_Mann> <http://dbpedia.org/ontology/abstract> ?abstract} } but yet I'm not able to see anything. please help me as I am beginner in semantic web!

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  • How to implement or emulate an "abstract" OCUnit test class?

    - by Quinn Taylor
    I have a number of Objective-C classes organized in an inheritance hierarchy. They all share a common parent which implements all the behaviors shared among the children. Each child class defines a few methods that make it work, and the parent class raises an exception for the methods designed to be implemented/overridden by its children. This effectively makes the parent a pseudo-abstract class (since it's useless on its own) even though Objective-C doesn't explicitly support abstract classes. The crux of this problem is that I'm unit testing this class hierarchy using OCUnit, and the tests are structured similarly: one test class that exercises the common behavior, with a subclass corresponding to each of the child classes under test. However, running the test cases on the (effectively abstract) parent class is problematic, since the unit tests will fail in spectacular fashion without the key methods. (The alternative of repeating the common tests across 5 test classes is not really an acceptable option.) The non-ideal solution I've been using is to check (in each test method) whether the instance is the parent test class, and bail out if it is. This leads to repeated code in every test method, a problem that becomes increasingly annoying if one's unit tests are highly granular. In addition, all such tests are still executed and reported as successes, skewing the number of meaningful tests that were actually run. What I'd prefer is a way to signal to OCUnit "Don't run any tests in this class, only run them in its child classes." To my knowledge, there isn't (yet) a way to do that, something similar to a +(BOOL)isAbstractTest method I can implement/override. Any ideas on a better way to solve this problem with minimal repetition? Does OCUnit have any ability to flag a test class in this way, or is it time to file a Radar? Edit: Here's a link to the test code in question. Notice the frequent repetition of if (...) return; to start a method, including use of the NonConcreteClass() macro for brevity.

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  • C# Item system design approach, should I use abstract classes, interfaces or virutals?

    - by vexe
    I'm working on a Resident Evil 1/2/3/0/Remake type of game. Currently I've done a big part of the inventory system (here's a link if you wanna see my inventory, pretty outdated, added a lot of features and made a lot of enhancements) Now I'm thinking about how to approach the items system, If you've played any Resident Evil game or any of its likes you should be familiar with what I'm trying to achieve. Here's a very simple category I made for the items: So you have different items, with different operations you could perform on them, there are usable items that you could use, like for example herbs and first aid kits that 'using' them would affect your health, keys to unlock doors, and equipable items that you could 'equip' like weapons. Also, you can 'combine' two items together to get new one, like for example mixing a green and red herb would give you a new type of herb, or combining a lighter with a paper, would give you a burnt paper, or ammo with a gun, would reload the gun or something. etc. You know the usual RE drill. Not all items are 'transformable', in that, for example: lighter + paper = burnt paper (it's the paper that 'transforms' to burnt paper and not the lighter, the lighter is not transformable it will remain as it is) green herb + red herb = newHerb1 (both herbs will vanish and transform to this new type of herb) ammo + gun = reload gun (ammo state will remain as it is, it won't change but it will just decrease, nothing will happen to the gun it just gets reloaded) Also a key note to remember is that you can't just combine items randomly, each item has a 'mating' item(s). So to sum up, different items, and different operations on them. The question is, how to approach this, design-wise? I've been learning about interfaces, but it just doesn't quite get into my head, I mean, why not just use classes with the good old inheritance? I know the technical details of interfaces and that the cool thing about them is that they don't require an inheritance chain, but I just can't see how to use them properly, that is, if they were the right thing to use here. So should I go with just classes and inheritance? just like in the tree I showed you? or should I think more about how to use interfaces? (IUsable, IEquipable, ITransformable) - why not just use classes UsableItem, Equipable item, TransformableItem? I want something that won't give me headaches in the long run, something resilient/flexible to future changes. I'm OK using classes, but I smell something better here. The way I'm thinking is to possibly use both inheritance and interfaces, so that you have a branch like this: item - equipable - weapon. but then again, the weapon has methods like 'reload' 'examine' 'equip' some of them 'combine' so I'm thinking to make weapon implement ICombinable?... not all items get used the same way, using herbs will increase your health, using a key will open a door, so IUsable maybe? Should I use a big database (XML for example) for all the items, items names, mates, nRowsReq, nColsReq, etc? Thanks so much for your answers in advanced, note that demo 3 is coming after I'm done with items :D

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  • Process arbitrarily large lists without explicit recursion or abstract list functions?

    - by Erica Xu
    This is one of the bonus questions in my assignment. The specific questions is to see the input list as a set and output all subsets of it in a list. We can only use cons, first, rest, empty?, empty, lambda, and cond. And we can only define exactly once. But after a night's thinking I don't see it possible to go through the arbitrarily long list without map or foldr. Is there a way to perform recursion or alternative of recursion with only these functions?

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  • When to decide to introduce interfaces (pure abstract base classes) in C++?

    - by Honza Brabec
    Assume that you are developing a functionality and are 90% sure that the implementation class will stay alone. If I was in this position in Java I would probably not use the interface right now to keep the things simple. In Java it is easy to refactor the code and extract the interface later. In C++ the refactoring is not always so easy. It may require replacing values with smart pointers (because of the introduction of polymorphism) and other non-trivial tasks. On the other hand I don't much like the idea of introducing virtual calls when I am 90% sure they won't be needed. After all speed is one of the reasons to prefer C++ over simpler languages.

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  • Breaking up a large PHP object used to abstract the database. Best practices?

    - by John Kershaw
    Two years ago it was thought a single object with functions such as $database->get_user_from_id($ID) would be a good idea. The functions return objects (not arrays), and the front-end code never worries about the database. This was great, until we started growing the database. There's now 30+ tables, and around 150 functions in the database object. It's getting impractical and unmanageable and I'm going to be breaking it up. What is a good solution to this problem? The project is large, so there's a limit to the extent I can change things. My current plan is to extend the current object for each table, then have the database object contain these. So, the above example would turn into (assume "user" is a table) $database->user->get_user_from_id($ID). Instead of one large file, we would have a file for every table.

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  • Liskov principle: violation by type-hinting

    - by Elias Van Ootegem
    According to the Liskov principle, a construction like the one below is invalid, as it strengthens a pre-condition. I know the example is pointless/nonsense, but when I last asked a question like this, and used a more elaborate code sample, it seemed to distract people too much from the actual question. //Data models abstract class Argument { protected $value = null; public function getValue() { return $this->value; } abstract public function setValue($val); } class Numeric extends Argument { public function setValue($val) { $this->value = $val + 0;//coerce to number return $this; } } //used here: abstract class Output { public function printValue(Argument $arg) { echo $this->format($arg); return $this; } abstract public function format(Argument $arg); } class OutputNumeric extends Output { public function format(Numeric $arg)//<-- VIOLATION! { $format = is_float($arg->getValue()) ? '%.3f' : '%d'; return sprintf($format, $arg->getValue()); } } My question is this: Why would this kind of "violation" be considered harmful? So much so that some languages, like the one I used in this example (PHP), don't even allow this? I'm not allowed to strengthen the type-hint of an abstract method but, by overriding the printValue method, I am allowed to write: class OutputNumeric extends Output { final public function printValue(Numeric $arg) { echo $this->format($arg); } public function format(Argument $arg) { $format = is_float($arg->getValue()) ? '%.3f' : '%d'; return sprintf($format, $arg->getValue()); } } But this would imply repeating myself for each and every child of Output, and makes my objects harder to reuse. I understand why the Liskov principle exists, don't get me wrong, but I find it somewhat difficult to fathom why the signature of an abstract method in an abstract class has to be adhered to so much stricter than a non-abstract method. Could someone explain to me why I'm not allowed to hind at a child class, in a child class? The way I see it, the child class OutputNumeric is a specific use-case of Output, and thus might need a specific instance of Argument, namely Numeric. Is it really so wrong of me to write code like this?

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  • i don't solve "must declare a body because it is not marked abstract, extern, or partial" problem?

    - by programmerist
    How can i solve "must declare a body because it is not marked abstract, extern, or partial". This problem. Can you show me some advices? Full Error message is about Save, Update, Delete, Select events... Full message sample : GenoTip.DAL._AccessorForSQL.Save(string, System.Collections.Specialized.ListDictionary, System.Data.CommandType)' must declare a body because it is not marked abstract, extern, or partial This error also return in Update, Delete, Select... public abstract class _AccessorForSQL { public virtual bool Save(string sp, ListDictionary ld, CommandType cmdType); public virtual bool Update(); public virtual bool Delete(); public virtual DataSet Select(); } class GenAccessor : _AccessorForSQL { DataSet ds; DataTable dt; public override bool Save(string sp, ListDictionary ld, CommandType cmdType) { SqlConnection con = null; SqlCommand cmd = null; SqlDataReader dr = null; try { con = GetConnection(); cmd = new SqlCommand(sp, con); con.Open(); cmd.CommandType = cmdType; foreach (string ky in ld.Keys) { cmd.Parameters.AddWithValue(ky, ld[ky]); } dr = cmd.ExecuteReader(); ds = new DataSet(); dt = new DataTable(); ds.Tables.Add(dt); ds.Load(dr, LoadOption.OverwriteChanges, dt); } catch (Exception exp) { HttpContext.Current.Trace.Warn("Error in GetCustomerByID()", exp.Message, exp); } finally { if (dr != null) dr.Close(); if (con != null) con.Close(); } return (ds.Tables[0].Rows.Count 0) ? true : false; } public override bool Update() { return true; } public override bool Delete() { return true; } public override DataSet Select() { DataSet dst = new DataSet(); return dst; } private static SqlConnection GetConnection() { string connStr = WebConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString; SqlConnection conn = new SqlConnection(connStr); return conn; }

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  • How is it that the abstract class XmlWriter can be instantiated using XmlWriter.Create(... ?

    - by Cognize
    Hi, Just looking to clarify my understanding of the workings of the XmlWriter and abstract classes in general. My thinking is (was) that an abstract class can not be instantiated, although it can contain base methods that can be used by an inheriting class. So, while investigating XmlWriter, I find that to instantiate the XmlWriter, you call XmlWriter.Create(.... , which returns an instance of... XmlWriter, which can then be used: FileStream fs = new FileStream("XML.xml", FileMode.Create); XmlWriter w = XmlWriter.Create(fs); XmlSerializer xmlSlr = new XmlSerializer(typeof(TestClass)); xmlSlr.Serialize(fs, tsIn); This clearly works, as tested. Can anyone help me understand what is going on here. As far as I can see there is or should be no 'instance' to work with here??

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  • Can the get of a property be abstract and the set be virtual?

    - by K. Georgiev
    I have a base class like this: public class Trajectory{ public int Count { get; set; } public double Initial { get; set { Count = 1; } } public double Current { get; set { Count ++ ; } } } So, I have code in the base class, which makes the set-s virtual, but the get-s must stay abstract. So I need something like this: ... public double Initial { abstract get; virtual set { Count = 1; } } ... But this code gives an error. The whole point is to implement the counter functionality in the base class instead in all the derived classes. So, how can I make the get and set of a property with different modifiers?

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  • Can't view order in magento

    - by koko
    Hi, I've been setting up a fresh magento 1.4.0.1 install, working great so far. I did some test orders just to see. Everything works fine, but when I click on "view order" under "my orders", I get a bunch of error messages: There has been an error processing your request Notice: iconv_substr() [function.iconv-substr]: Unknown error (0) in /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Helper/String.php on line 98 Trace: #0 [internal function]: mageCoreErrorHandler(8, 'iconv_substr() ...', '/data/web/A1423...', 98, Array) #1 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Helper/String.php(98): iconv_substr('1', 0, 50, 'UTF-8') #2 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Helper/String.php(173): Mage_Core_Helper_String-substr('1', 0, 50) #3 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Helper/String.php(112): Mage_Core_Helper_String-str_split('1', 50) #4 /data/web/A14237/htdocs/magento/app/design/frontend/base/default/template/sales/order/items/renderer/default.phtml(58): Mage_Core_Helper_String-splitInjection('1') #5 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(189): include('/data/web/A1423...') #6 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(225): Mage_Core_Block_Template-fetchView('frontend/base/d...') #7 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(242): Mage_Core_Block_Template-renderView() #8 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(674): Mage_Core_Block_Template-_toHtml() #9 /data/web/A14237/htdocs/magento/app/code/core/Mage/Sales/Block/Items/Abstract.php(137): Mage_Core_Block_Abstract-toHtml() #10 /data/web/A14237/htdocs/magento/app/design/frontend/base/default/template/sales/order/items.phtml(52): Mage_Sales_Block_Items_Abstract-getItemHtml(Object(Mage_Sales_Model_Order_Item)) #11 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(189): include('/data/web/A1423...') #12 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(225): Mage_Core_Block_Template-fetchView('frontend/base/d...') #13 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(242): Mage_Core_Block_Template-renderView() #14 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(674): Mage_Core_Block_Template-_toHtml() #15 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(516): Mage_Core_Block_Abstract-toHtml() #16 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(467): Mage_Core_Block_Abstract-_getChildHtml('order_items', true) #17 /data/web/A14237/htdocs/magento/app/design/frontend/base/default/template/sales/order/view.phtml(64): Mage_Core_Block_Abstract-getChildHtml('order_items') #18 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(189): include('/data/web/A1423...') #19 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(225): Mage_Core_Block_Template-fetchView('frontend/base/d...') #20 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(242): Mage_Core_Block_Template-renderView() #21 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(674): Mage_Core_Block_Template-_toHtml() #22 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(516): Mage_Core_Block_Abstract-toHtml() #23 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(463): Mage_Core_Block_Abstract-_getChildHtml('sales.order.vie...', true) #24 /data/web/A14237/htdocs/magento/app/code/core/Mage/Page/Block/Html/Wrapper.php(52): Mage_Core_Block_Abstract-getChildHtml('', true, true) #25 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(674): Mage_Page_Block_Html_Wrapper-_toHtml() #26 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Text/List.php(43): Mage_Core_Block_Abstract-toHtml() #27 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(674): Mage_Core_Block_Text_List-_toHtml() #28 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(516): Mage_Core_Block_Abstract-toHtml() #29 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(467): Mage_Core_Block_Abstract-_getChildHtml('content', true) #30 /data/web/A14237/htdocs/magento/app/design/frontend/base/default/template/page/2columns-left.phtml(48): Mage_Core_Block_Abstract-getChildHtml('content') #31 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(189): include('/data/web/A1423...') #32 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(225): Mage_Core_Block_Template-fetchView('frontend/base/d...') #33 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Template.php(242): Mage_Core_Block_Template-renderView() #34 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Block/Abstract.php(674): Mage_Core_Block_Template-_toHtml() #35 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Model/Layout.php(536): Mage_Core_Block_Abstract-toHtml() #36 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Controller/Varien/Action.php(389): Mage_Core_Model_Layout-getOutput() #37 /data/web/A14237/htdocs/magento/app/code/core/Mage/Sales/controllers/OrderController.php(100): Mage_Core_Controller_Varien_Action-renderLayout() #38 /data/web/A14237/htdocs/magento/app/code/core/Mage/Sales/controllers/OrderController.php(136): Mage_Sales_OrderController-_viewAction() #39 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Sales_OrderController-viewAction() #40 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(254): Mage_Core_Controller_Varien_Action-dispatch('view') #41 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Controller/Varien/Front.php(177): Mage_Core_Controller_Varien_Router_Standard-match(Object(Mage_Core_Controller_Request_Http)) #42 /data/web/A14237/htdocs/magento/app/code/core/Mage/Core/Model/App.php(304): Mage_Core_Controller_Varien_Front-dispatch() #43 /data/web/A14237/htdocs/magento/app/Mage.php(596): Mage_Core_Model_App-run(Array) #44 /data/web/A14237/htdocs/magento/index.php(78): Mage::run('', 'store') #45 {main} gtx, koko

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  • mysql error using Rails-- Please help

    - by Cypher
    Alright I am sry for the noob question but this has been driving me up a wall-especially because I got it to work yesterday and I can't remember what I did.... I am just trying to use mysql with rails with a mongrel server. I set up the server fine and can run rails applications that don't need mysql but when I create a project using (for example) rails -d mysql blog and then create some simple controller e.g. ruby script/generate Test then put this code in the controller... class TestController < ApplicationController def index render :text => 'WORK' end end then when I start the server up and open up localhost:3000/test I get the following error: = Booting Mongrel = Rails 2.3.5 application starting on http://0.0.0.0:3000 = Call with -d to detach = Ctrl-C to shutdown server /!\ FAILSAFE /!\ Mon May 10 20:15:06 -0500 2010 Status: 500 Internal Server Error Can't connect to MySQL server on 'localhost' (10061) C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/mysql_adapter.rb:589:in 'real_connect' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/mysql_adapter.rb:589:in 'connect' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/mysql_adapter.rb:203:in 'initialize' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/mysql_adapter.rb:75:in 'new' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/mysql_adapter.rb:75:in 'mysql_connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/abstract/connection_pool.rb:223:in 'send' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/abstract/connection_pool.rb:223:in 'new_connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/abstract/connection_pool.rb:245:in 'checkout_new_connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/abstract/connection_pool.rb:188:in 'checkout' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/abstract/connection_pool.rb:184:in 'loop' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/abstract/connection_pool.rb:184:in 'checkout' C:/Ruby/lib/ruby/1.8/monitor.rb:242:in 'synchronize' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/abstract/connection_pool.rb:183:in 'checkout' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/abstract/connection_pool.rb:98:in 'connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/abstract/connection_pool.rb:326:in 'retrieve_connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/abstract/connection_specification.rb:123:in 'retrieve_connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapter s/abstract/connection_specification.rb:115:in 'connection' etc... In the browser i get a 'We're sorry, but something went wrong' Does anyone know what I am doing wrong?

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  • Is there any way to abstract IP address during ssh?

    - by Vivek V K
    I have a server which is in the middle of a forest. It is connected to the Internet via a microwave link and an ADSL link.Hence it has two different static IP addresses. Now if there is heavy rain, the microwave link breaks and I should use the much slower ADSL link. And I ping the microwave ip time to time to check if it is up again . But at times, I end up using the very slow ADSL link even if the microwave link is back up. Hence I need a way to automate this in the following way. 1.I need to abstract the IP address of the machine with some other name which when I use ssh or sftp, will poll both the IP and connect me to the best one. so for eg: if I say ssh -Y name@server, It should first try to connect to the microwave link if it cant, then connect to ADSL. 2.Suppose the first time I connect, the microwave link is down so it connects to ADSL, I need it to dynamically change to the microwave link once it is working again. Is this even possible?

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  • Rails with Oracle often got "no listener" error

    - by qichunren
    I am on Rails 2.3.5 and use oracle 10 as my database,use oracle_adapter ,ruby-oci8 to connect oracle host. But I often got exception as the log info show: Completed in 463ms (View: 18, DB: 166) | 200 OK [http://192.168.30.128/auctions?page=1] /!\ FAILSAFE /!\ Mon Feb 01 19:02:11 +0800 2010 Status: 500 Internal Server Error ORA-12541: TNS:no listener env.c:257:in oci8lib.so /home/qichunren/.gem/ruby/1.8/gems/ruby-oci8-1.0.7/lib/oci8.rb:229:in `initialize' /home/qichunren/.gem/ruby/1.8/gems/activerecord-oracle-adapter-1.0.0.9250/lib/active_record/connection_adapters/oracle_adapter.rb:623:in `new' /home/qichunren/.gem/ruby/1.8/gems/activerecord-oracle-adapter-1.0.0.9250/lib/active_record/connection_adapters/oracle_adapter.rb:623:in `new_connection' /home/qichunren/.gem/ruby/1.8/gems/activerecord-oracle-adapter-1.0.0.9250/lib/active_record/connection_adapters/oracle_adapter.rb:659:in `initialize' /home/qichunren/.gem/ruby/1.8/gems/activerecord-oracle-adapter-1.0.0.9250/lib/active_record/connection_adapters/oracle_adapter.rb:35:in `new' /home/qichunren/.gem/ruby/1.8/gems/activerecord-oracle-adapter-1.0.0.9250/lib/active_record/connection_adapters/oracle_adapter.rb:35:in `oracle_connection' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:223:in `send' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:223:in `new_connection' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:245:in `checkout_new_connection' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:188:in `checkout' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:184:in `loop' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:184:in `checkout' /usr/local/ruby187/lib/ruby/1.8/monitor.rb:242:in `synchronize' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:183:in `checkout' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:98:in `connection' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:326:in `retrieve_connection' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_specification.rb:123:in `retrieve_connection' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_specification.rb:115:in `connection' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/query_cache.rb:9:in `cache' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/query_cache.rb:28:in `call' /home/qichunren/.gem/ruby/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:361:in `call' /home/qichunren/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/string_coercion.rb:25:in `call' /home/qichunren/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/head.rb:9:in `call' /home/qichunren/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/methodoverride.rb:24:in `call' /home/qichunren/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/params_parser.rb:15:in `call' /home/qichunren/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/session/cookie_store.rb:93:in `call' /home/qichunren/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/failsafe.rb:26:in `call' /home/qichunren/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:in `call' /home/qichunren/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:in `synchronize' /home/qichunren/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:in `call' /home/qichunren/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:114:in `call' /home/qichunren/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/reloader.rb:34:in `run' /home/qichunren/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:108:in `call' /home/qichunren/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/cgi_process.rb:44:in `dispatch_cgi' /home/qichunren/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:101:in `dispatch_cgi' /home/qichunren/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:27:in `dispatch' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel/rails.rb:76:in `process' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel/rails.rb:74:in `synchronize' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel/rails.rb:74:in `process' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel.rb:159:in `process_client' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel.rb:158:in `each' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel.rb:158:in `process_client' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel.rb:285:in `run' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel.rb:285:in `initialize' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel.rb:285:in `new' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel.rb:285:in `run' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel.rb:268:in `initialize' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel.rb:268:in `new' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel.rb:268:in `run' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel/configurator.rb:282:in `run' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel/configurator.rb:281:in `each' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel/configurator.rb:281:in `run' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:128:in `run' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/../lib/mongrel/command.rb:212:in `run' /home/qichunren/.gem/ruby/1.8/gems/mongrel-1.1.5/bin/mongrel_rails:281 /home/qichunren/.gem/ruby/1.8/bin/mongrel_rails:19:in `load' /home/qichunren/.gem/ruby/1.8/bin/mongrel_rails:19 it seems that connection to oracle often disconnect.it show oracle error:ORA-12541: TNS:no listener How to fix this ? Many tks. oci8.c:270:in oci8lib.so: ORA-12541: TNS:no listener (OCIError) from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-oracle_enhanced-adapter-1.2.4/lib/active_record/connec tion_adapters/oracle_enhanced_oci_connection.rb:223:in new' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-oracle_enhanced-adapter-1.2.4/lib/active_record/connec tion_adapters/oracle_enhanced_oci_connection.rb:223:innew_connection' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-oracle_enhanced-adapter-1.2.4/lib/active_record/connec tion_adapters/oracle_enhanced_oci_connection.rb:328:in initialize' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-oracle_enhanced-adapter-1.2.4/lib/active_record/connec tion_adapters/oracle_enhanced_oci_connection.rb:24:innew' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-oracle_enhanced-adapter-1.2.4/lib/active_record/connec tion_adapters/oracle_enhanced_oci_connection.rb:24:in initialize' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-oracle_enhanced-adapter-1.2.4/lib/active_record/connec tion_adapters/oracle_enhanced_connection.rb:9:innew' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-oracle_enhanced-adapter-1.2.4/lib/active_record/connec tion_adapters/oracle_enhanced_connection.rb:9:in create' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-oracle_enhanced-adapter-1.2.4/lib/active_record/connec tion_adapters/oracle_enhanced_adapter.rb:50:inoracle_enhanced_connection' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/abstract/c onnection_specification.rb:291:in send' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/abstract/c onnection_specification.rb:291:inconnection=' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/abstract/c onnection_specification.rb:259:in retrieve_connection' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/abstract/c onnection_specification.rb:78:inconnection' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/base.rb:2438:in quoted_table_ name' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/base.rb:1259:infind_one' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/base.rb:1250:in find_from_ids ' from /opt/ruby-enterprise-1.8.7/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/base.rb:504:infind' from script/maintenance/adjust_settlement.rb:19

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  • Using abstract base to implement private parts of a template class?

    - by StackedCrooked
    When using templates to implement mix-ins (as an alternative to multiple inheritance) there is the problem that all code must be in the header file. I'm thinking of using an abstract base class to get around that problem. Here's a code sample: class Widget { public: virtual ~Widget() {} }; // Abstract base class allows to put code in .cpp file. class AbstractDrawable { public: virtual ~AbstractDrawable() = 0; virtual void draw(); virtual int getMinimumSize() const; }; // Drawable mix-in template<class T> class Drawable : public T, public AbstractDrawable { public: virtual ~Drawable() {} virtual void draw() { AbstractDrawable::draw(); } virtual int getMinimumSize() const { return AbstractDrawable::getMinimumSize(); } }; class Image : public Drawable< Widget > { }; int main() { Image i; i.draw(); return 0; } Has anyone walked that road before? Are there any pitfalls that I should be aware of?

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