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• How to track history of db tables that include many-to-many mapping tables?

  - by chacmool

  I have seen several questions here on tracking db history, but can't seem to find one that matches our situation. We need to track the history of several tables, some of which are many-to-many linking tables. Eg say we have this schema: EntityA id name EntityB id name ABLink A_id B_id So, tracking changes to EntityA or EntityB seems pretty straightforward. We can keep a log table with the same columns plus a date stamp and user. But what about the links? How do we maintain the set of links that are valid for a given version of the data? We need to be able to recreate a history of the data showing changes in chronological order. So if a link added or deleted, we indicate that. Etc.

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• How can I call a method on a custom object created in JavaScript using C#?

  - by just in case

  I have a WebBrowser control. I have added some JavaScript into the head tag and I can see it is working as expected by adding an alert. Inside of this js I am creating a function and adding some members to it's prototype like so: function test() { } test.prototype.run = function() { alert('success!') } function createTest() { return new test() } Then back inside of C# I am doing: dynamic test = this.browser.InvokeScript("createTest"); test.run(); I can see that the test object is some ComObject but when I call run() nothing happens. I get no error but nothing happens. Does anyone know how to call this type of custom object? Also suppose I wanted to get rid of the createTest() method, how can I create a new instance of test from C#? Also, for bonus points, is there anything special I need to know about attaching events to this custom object (on say a 'complete' member) such that it will callback into my C# code?

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• Mapping one to one foreign key relationships in Entity Framework 4.0?

  - by John K.

  Hello all, I'm sure I'm missing something very simple, but let's say I have two entities, Employee and EmployeeType. Employee type would contain values like 'Full time', 'Contractor', 'Intern', etc. An Employee entity would contain one, and only one EmployeeType value. So I am designing a new .edmx model using the Model-First approach and generating my actual sql server data schema from the model. I want to add an integer type foreign key id into my Employee entity, EmployeeTypeId, which will map to the primary key of the EmployeeType entity. So I've gone ahead and done that in my Employee entity. Where I'm stuck is how, though the Entity Framework designer, to enforce the 1:1 referential constraint on that EmployeeTypeId property? Or does the EF handle that automatically behind the scenes? thanks in advance, John

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• Why Is my json-object from AJAX not understood by javascript, even with 'json' dataType?

  - by pete

  My js code simply gets a json object from my server, but I think it should be automatically parsed and turned into an object with properties, yet it's not allowing access properly. $.ajax({ type: 'POST', url: '/misc/json-sample.js', data: {href: path}, // THIS IS THE POST DATA THAT IS PASSED IN TO THE DRUPAL MENU CALL TO GET THE MENU... dataType: 'json', success: function (datax) { if (datax.debug) { alert('Debug data: ' + datax.debug); } else { alert('No debug data: ' + datax.toSource() ) ; } The /misc/json-sample.js file is: [ { "path": "examplemodule/parent1/child1/grandchild1", "title": "First grandchild option", "children": false } ] (I have also been trying to return that object from drupal as follows, and the same results.) Drupal version of misc/json-sample.js: $items[] = array( 'path' = 'examplemodule/parent1/child1/grandchild1', 'title' = t('First grandchild option'), 'debug' = t('debug me!'), 'children' = FALSE ); print drupal_to_js($items); What happens (in FF, which has the toSource() capability) is the alert with 'No debug data: [ { "path": "examplemodule/parent1/child1/grandchild1", "title": "First grandchild option", "children": false } ] Thanks

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• best practice for passing many arguments to method ?

  - by Tony

  Occasionally , we have to write methods that receive many many arguments , for example : public void doSomething(Object objA , Object objectB ,Date date1 ,Date date2 ,String str1 ,String str2 ) { } When I encounter this kind of problem , I often encapsulate arguments into a map. Map<Object,Object> params = new HashMap<Object,Object>(); params.put("objA",ObjA) ; ...... public void doSomething(Map<Object,Object> params) { // extracting params Object objA = (Object)params.get("objA"); ...... } This is not a good practice , encapsulate params into a map is totally a waste of efficiency. The good thing is , the clean signature , easy to add other params with fewest modification . what's the best practice for this kind of problem ?

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• How do I find the angle required to point to another object?

  - by Ginamin

  I am making an air combat game, where you can fly a ship in a 3D space. There is an opponent that flies around as well. When the opponent is not on screen, I want to display an arrow pointing in the direction the user should turn, as such: So, I took the camera location and the oppenent location and did this: double newDirection = atan2(activeCamera.location.y-ship_wrap.location.y, activeCamera.location.x-ship_wrap.location.x); After which, I get the position on the circumferance of a circle which surrounds my crosshairs, like such: trackingArrow.position = point((60*sin(angle)+240),60*cos(angle)+160); It all works fine, except it's the wrong angle! I assume my calculation for the new direction is incorrect. Can anyone help?

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• Why "cannot use an object as a parameter to a method"?

  - by Martin

  I have the following ViewController class #import <UIKit/UIKit.h> @interface SampleViewController : UIViewController { IBOutlet UITextField *field1; } @property (nonatomic, retain) UITextField *field1; - (IBAction) method1:(id)sender; @end When I change the method1:(id)sender to method1:(UITextField)sender, I get the error "Cannot use an object as a parameter to a method". I searched and found this post which says "it [using an object as a method parameter] is not a good idea in Objective-C because Objective-C does not allow statically allocated object". Can anyone point out where I can find a more detailed explanation for this? Thank you.

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• How to disable UI control based on domain object's state?

  - by Subb

  Here's my problem. I have a somewhat complex domain object, which, depending on its state, responds to certain actions. I think the state pattern is pretty much the solution for that. However, I need to display which actions are possible at any moment in the UI. Ex: The domain object is an audio player. Some songs can't be skipped (like ads), so I need to disable the "next" and "previous" buttons in the GUI so the user have some kind of feedback of which action he can execute. I've looked at Swing's Action class (note: this is not a Java project), but I think I would need to keep every Actions in my domain object class (audio player), so it can enable or disable them depending on its own state (thus, affecting the UI). Is it the way to do it?

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• What common interface would be appropriate for these game object classes?

  - by Jefffrey

  Question A component based system's goal is to solve the problems that derives from inheritance: for example the fact that some parts of the code (that are called components) are reused by very different classes that, hypothetically, would lie in a very different branch of the inheritance tree. That's a very nice concept, but I've found out that CBS is often hard to accomplish without using ugly hacks. Implementations of this system are often far from clean. But I don't want to discuss this any further. My question is: how can I solve the same problems a CBS try to solve with a very clean interface? (possibly with examples, there are a lot of abstract talks about the "perfect" design already). Context Here's an example I was going for before realizing I was just reinventing inheritance again: class Human { public: Position position; Movement movement; Sprite sprite; // other human specific components }; class Zombie { Position position; Movement movement; Sprite sprite; // other zombie specific components }; After writing that I realized I needed an interface, otherwise I would have needed N containers for N different types of objects (or to use boost::variant to gather them all together). So I've thought of polymorphism (move what systems do in a CBS design into class specific functions): class Entity { public: virtual void on_event(Event) {} // not pure virtual on purpose virtual void on_update(World) {} virtual void on_draw(Window) {} }; class Human : public Entity { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; class Zombie : public Entity { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; Which was nice, except for the fact that now the outside world would not even be able to know where a Human is positioned (it does not have access to its position member). That would be useful to track the player position for collision detection or if on_update the Zombie would want to track down its nearest human to move towards him. So I added const Position& get_position() const; to both the Zombie and Human classes. And then I realized that both functionality were shared, so it should have gone to the common base class: Entity. Do you notice anything? Yes, with that methodology I would have a god Entity class full of common functionality (which is the thing I was trying to avoid in the first place). Meaning of "hacks" in the implementation I'm referring to I'm talking about the implementations that defines Entities as simple IDs to which components are dynamically attached. Their implementation can vary from C-stylish: int last_id; Position* positions[MAX_ENTITIES]; Movement* movements[MAX_ENTITIES]; Where positions[i], movements[i], component[i], ... make up the entity. Or to more C++-style: int last_id; std::map<int, Position> positions; std::map<int, Movement> movements; From which systems can detect if an entity/id can have attached components.

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• Game Editor - When screen is clicked, how do you identify which object that is clicked?

  - by Deukalion

  I'm trying to create a Game Editor, currently just placing different types of Shapes and such. I'm doing this in Windows Forms while drawing the 3D with XNA. So, if I have a couple of Shapes on the screen and I click the screen I want to be able to identify "which" of these objects you clicked. What is the best method for this? Since having two objects one behind the other, it should be able to recognize the one in front and not the one behind it and also if I rotate the camera and click on the one behind it - it should identify it and not the first one. Are there any smart ways to go about this?

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• Hibernate configuration - session factory scanning?

  - by Marcus

  We have this hibernate.cfg.xml file. Is there a way to tell Hibernate to just scan a directory instead of having to add an entry here for each class? <hibernate-configuration> <session-factory> <mapping class="com.abc.domain.model.A" /> <mapping class="com.abc.domain.model.B" /> <mapping class="com.abc.domain.model.C" /> <mapping class="com.abc.domain.model.D" /> <mapping class="com.abc.domain.model.E" /> </session-factory> </hibernate-configuration>

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• How to make Entity Key Mapping in Entity Framework like sql's foreign key?

  - by programmerist

  I try to give entity map on my entity app. But how can I do it? I try to make it like below: var test = ( from k in Kartlar where k.Rehber..... above codes k.(can not see Rehber or not working ) if you are correct , i can write k.Rehber.ID and others. i can not write: from k in Kartlar where k.Rehber.ID = 123 //assuming that navigation property name is Rehbar and its primary key of Rehbar table is ID && k.Kampanya.ID = 345 //assuming that navigation property name is Kampanya and its primary //key of Kampanya table is ID && k.Birim.ID = 567 //assuming that navigation property name is Birim and its primary key of Birim table is ID select k images you can see: also: You should look : http://i42.tinypic.com/2nqyyc6.png I have a table it includes 3 foreign key field like that: My Table: Kartlar ID (Pkey) RehberID (Fkey) KampanyaID (Fkey) BrimID (Fkey) Name Detail How can i write entity query with LINQ ? select * from Kartlar where RehberID=123 and KampanyaID=345 and BrimID=567 BUT please be careful I can not see RehberID, KampanyaID, BrimID in entity they are foreign key. I should use entity key but how?

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• Has anyone used an object database with a large amount of data?

  - by Jon Kruger

  Object databases like MongoDB and db4o are getting lots of pub lately. Everyone that plays with them seems to love it. I'm guessing that they are dealing with about 640K of data in their sample apps. Has anyone tried to use an object database with a large amount of data (say, 50GB or more)? Are you able to still execute complex queries against it (like from a search screen)? How does it compare to your usual relational database of choice? I'm just curious. I want to take the object database plunge, but I need to know if it'll work on something more than a sample app.

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• Inherit all methods of object (including "constructor"), but modify some of them.

  - by Kirzilla

  Hello, Let's imagine that we have object Animal $.Animal = function(options) { this.defaults = { name : null } this.options = $.extend(this.defaults, options); } $.Animal.prototype.saySomething = function() { alert("I'm animal!"); } Now I'd like to create Cat object. It is absolutely similar to $.Annimal, but method saySomething() will look like this one... $.Cat.prototype.saySomething = function() { alert("I'm cat!"); } How can I inherit from Animal to create new object Cat and redefine saySomething() method? Thank you.

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• Have there been attempts to make object containers that search for valid programs by auto wiring compatible components?

  - by Aaron Anodide

  I hope this post isn't too "Fringe" - I'm sure someone will just kill it if it is :) Three things made me want to reach out about this now: Decoupling is so in the forefront of design. TDD inspires the idea that it doesn't matter how a program comes to exist as long as it works. Seeing how often the adapter pattern is applied to achieve (1). I'm almost sure this has been tried from a memory of reading about it around the year 2000 or so. If I had to guess, it was maybe about and earlier version of the Java Spring framework. At this time we were not so far from days when the belief was that computer programs could exhibit useful emergent behavior. I think the article said it didn't work, but it didn't say it was impossible. I wonder if since then it has been deemed impossible or simply an illusion due to a false assumption of similarity between a brain and a CPU. I know this illusion existed because I had an internship in 1996 where I programmed neural nets that were supposedly going to exhibit "brain damage". STILL, after all that, I'm sitting around this morning and not able to shake the idea that it should be possible to have a method of programming to allow autonomous components to find each other, attempt to collaborate and their outputs evaluated against a set desired results.

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• In Node.JS, how do I return an entire object from a separate .js file?

  - by Matthew Patrick Cashatt

  Thanks for looking. I am new to Node.js and trying to figure out how to request an object from a separate file (rather than just requesting a function) but everything I try--exports,module-exports,etc--is failing. So, for example, if I have foo.js: var methods = { Foobar:{ getFoo: function(){return "foo!!";}, getBar: function(){return "bar!!";} } }; And now I want to call a function within an object of foo.js from index.js: var m = require('./Methods'); function fooMain(){ return m.Foobar.getFoo(); }; How do I do this? I have tried all sorts of combinations of exports and module-exports but they seem to only work if I call a discrete function that is not part of an object. Thanks!

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• Hibernate without primary keys generated by db?

  - by Michael Jones

  I'm building a data warehouse and want to use InfiniDB as the storage engine. However, it doesn't allow primary keys or foreign key constraints (or any constraints for that matter). Hibernate complains "The database returned no natively generated identity value" when I perform an insert. Each table is relational, and contains a unique integer column that was previously used as the primary key - I want to keep that, but just not have the constraint in the db that the column is the primary key. I'm assuming the problem is that Hibernate expects the db to return a generated key. Is it possible to override this behaviour so I can set the primary key field's value myself and keep Hibernate happy? -- edit -- Two of the mappings are as follows: <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Jun 1, 2010 2:49:51 PM by Hibernate Tools 3.2.1.GA --> <hibernate-mapping> <class name="com.example.project.Visitor" table="visitor" catalog="orwell"> <id name="id" type="java.lang.Long"> <column name="id" /> <generator class="identity" /> </id> <property name="firstSeen" type="timestamp"> <column name="first_seen" length="19" /> </property> <property name="lastSeen" type="timestamp"> <column name="last_seen" length="19" /> </property> <property name="sessionId" type="string"> <column name="session_id" length="26" unique="true" /> </property> <property name="userId" type="java.lang.Long"> <column name="user_id" /> </property> <set name="visits" inverse="true"> <key> <column name="visitor_id" /> </key> <one-to-many class="com.example.project.Visit" /> </set> </class> </hibernate-mapping> and: <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Jun 1, 2010 2:49:51 PM by Hibernate Tools 3.2.1.GA --> <hibernate-mapping> <class name="com.example.project.Visit" table="visit" catalog="orwell"> <id name="id" type="java.lang.Long"> <column name="id" /> <generator class="identity" /> </id> <many-to-one name="visitor" class="com.example.project.Visitor" fetch="join" cascade="all"> <column name="visitor_id" /> </many-to-one> <property name="visitId" type="string"> <column name="visit_id" length="20" unique="true" /> </property> <property name="startTime" type="timestamp"> <column name="start_time" length="19" /> </property> <property name="endTime" type="timestamp"> <column name="end_time" length="19" /> </property> <property name="userAgent" type="string"> <column name="user_agent" length="65535" /> </property> <set name="pageViews" inverse="true"> <key> <column name="visit_id" /> </key> <one-to-many class="com.example.project.PageView" /> </set> </class> </hibernate-mapping>

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• Has Object in VB 2010 received the same optimalization as dynamic in C# 4.0?

  - by Abel

  Some people have argued that the C# 4.0 feature introduced with the dynamic keyword is the same as the "everything is an Object" feature of VB. However, any call on a dynamic variable will be translated into a delegate once and from then on, the delegate will be called. In VB, when using Object, no caching is applied and each call on a non-typed method involves a whole lot of under-the-hood reflection, sometimes totaling a whopping 400-fold performance penalty. Have the dynamic type delegate-optimization and caching also been added to the VB untyped method calls, or is VB's untyped Object still so slow?

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• Figuring out what object is closer to a certain point?

  - by user1157885

  I'm trying to create fog of war, I have the visual effect created but I'm not sure how to deal with the hiding of other players if they're within the fog of war. So right now the thing I'm trying to do is if another player is hiding behind a wall then not to render that player. I was thinking of doing it by sending a ray in the direction of all the players, and then creating a list of all the obstacles that ray collides with and then trying to figure out if an obstacle was closer than the player in order to predict the distance. But then I realized I'm not really sure how to figure out if the obstacle is infact closer or not because I have to account for all the dimensions, so I'm kind of stuck. First of all is this approach the correct way to go about it and secondly how would I calculate if the obstacle was infact closer taking into account the X Y and Z. Thanks

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• netbeans autocompletion when using singleton to retrieve object instead of new operator?

  - by fayer

  when i use the 'new' operator to instantiate a class, netbeans has no problem to autocomplete the members of the object. $instance = new Singleton(); $instance-> // shows test() method but when i use a singleton to retrieve an object it cannot autocomplete the members in the object retrieved. the getInstance code looks like this: public function test() { echo "hello"; } public static function getInstance() { if ( ! is_object(self::$_instance)) { self::$_instance = new self(); self::$_instance->initialize(); } return self::$_instance; } so i use: $instance = Singleton::getInstance(); $instance-> // no autocompletion! does anyone have the same problem? how do i work around it? thanks!

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• How do I draw a texture to a MSTerrain object?

  - by Brad

  I'm using Farseer to make a game in XNA and I can't seem to figure this out. I've decided to use MSTerrain for making my game's terrain because I wanted destructible terrain and MSTerrain seemed like the best bet. Unfortunately, I'm stumped on how to actually show the terrain. When I generate the terrain it's visible in debug view, but MSTerrain does not have a Draw method, so I'm wondering how it is supposed to be drawn to the screen? Is it worth pursuing? I'm starting to think that MSTerrain is more trouble than it's worth, is there another better way to do this with bodies?

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• How to Avoid a Busy Loop Inside a Function That Returns the Object That's Being Waited For

  - by Carl Smith

  I have a function which has the same interface as Python's input builtin, but it works in a client-server environment. When it's called, the function, which runs in the server, sends a message to the client, asking it to get some input from the user. The user enters some stuff, or dismisses the prompt, and the result is passed back to the server, which passes it to the function. The function then returns the result. The function must work like Python's input [that's the spec], so it must block until it has the result. This is all working, but it uses a busy loop, which, in practice, could easily be spinning for many minutes. Currently, the function tells the client to get the input, passing an id. The client returns the result with the id. The server puts the result in a dictionary, with the id as the key. The function basically waits for that key to exist. def input(): '''simplified example''' key = unique_key() tell_client_to_get_input(key) while key not in dictionary: pass return dictionary.pop(pin) Using a callback would be the normal way to go, but the input function must block until the result is available, so I can't see how that could work. The spec can't change, as Python will be using the new input function for stuff like help and pdb, which provide their own little REPLs. I have a lot of flexibility in terms of how everything works overall, but just can't budge on the function acting exactly like Python's. Is there any way to return the result as soon as it's available, without the busy loop?

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• Ruby on Rails: one-to-one mapping. Just semantics or really a different structure.

  - by Sam

  So I'm creating a plugin for Ruby on Rails to make implemented addresses including country, state, city, and zip_code for countries that can follow that paradigm a lot easier but that's beside the point expect for how the address model is associated. So starting with my address model. class Address < ActiveRecord::Base has_one :country has_one :state has_one :city has_one :zip_code end What's the difference between saying belongs_to and has_one Seems to be the same thing because both only require one model to declare ownership and foreign_key And it also seems that both are logical to say. an address belongs to an account and an account has one address Is this only semantics or is there are real difference

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• Is there a performance gain from defining routes in app.yaml versus one large mapping in a WSGIAppli

  - by jgeewax

  Scenario 1 This involves using one "gateway" route in app.yaml and then choosing the RequestHandler in the WSGIApplication. app.yaml - url: /.* script: main.py main.py from google.appengine.ext import webapp class Page1(webapp.RequestHandler): def get(self): self.response.out.write("Page 1") class Page2(webapp.RequestHandler): def get(self): self.response.out.write("Page 2") application = webapp.WSGIApplication([ ('/page1/', Page1), ('/page2/', Page2), ], debug=True) def main(): wsgiref.handlers.CGIHandler().run(application) if __name__ == '__main__': main() Scenario 2: This involves defining two routes in app.yaml and then two separate scripts for each (page1.py and page2.py). app.yaml - url: /page1/ script: page1.py - url: /page2/ script: page2.py page1.py from google.appengine.ext import webapp class Page1(webapp.RequestHandler): def get(self): self.response.out.write("Page 1") application = webapp.WSGIApplication([ ('/page1/', Page1), ], debug=True) def main(): wsgiref.handlers.CGIHandler().run(application) if __name__ == '__main__': main() page2.py from google.appengine.ext import webapp class Page2(webapp.RequestHandler): def get(self): self.response.out.write("Page 2") application = webapp.WSGIApplication([ ('/page2/', Page2), ], debug=True) def main(): wsgiref.handlers.CGIHandler().run(application) if __name__ == '__main__': main() Question What are the benefits and drawbacks of each pattern? Is one much faster than the other?

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• What is a useful pattern to maintaining an object state in a one to many relationship?

  - by ahenderson

  I am looking for a design for my application, here are the players(classes) involved. struct Transform { // Uses a matrix to transform the position. // Also acts acts as the state of a Dialog. Position transform(Position p); //other methods. }; struct Dialog { // There are multiple dialog for the user to transform the output. Transform& t; void ChangeTranformation(){t.rotate(360);} } struct Algorithm { //gives us a position based on an implementation. For example this can return points on a circle or line. Transform& t; Position m_p; Dialog& d; Position GetCurrentPosition(){ return t.transform(m_p);} //other methods. } Properties I need: Each algorithms has one dialog and each dialog can have many algorithms associated with it. When the user selects an algorithm a dialog associated with that algorithm is displayed. If the user selects a different algorithm then re-selects back the state is restored in the dialog. Basically I want a good design pattern to maintain the state of the dialog given that many algorithms use it and they can be switched back and forth. Does anyone have any suggestions? Here is a use case: Dialog1 has a single edit box to control the radius. Algorithm1 generates points on a unit circle. Algorithm2 is the same as Algorithm1. The user has selected Algorithm1 and entered 2 into the edit box. This will generate points on a circle of radius 2. The user then selects Algorithm2 and enters 10 into the edit box of Dialog1. This will generate points on a circle of radius 10. Finally Algorithm1 is selected again. The edit box of Dialog1 should show 2 and points on a circle of radius 2 should be generated.

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