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• Creating ActionEvent object for CustomButton in Java

  - by Crystal

  For a hw assignment, we were supposed to create a custom button to get familiar with swing and responding to events. We were also to make this button an event source which confuses me. I have an ArrayList to keep track of listeners that would register to listen to my CustomButton. What I am getting confused on is how to notify the listeners. My teacher hinted at having a notify and overriding actionPerformed which I tried doing, but then I wasn't sure how to create an ActionEvent object looking at the constructor documentation. The source, id, string all confuses me. Any help would be appreciated. Thanks! code: import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.util.List; import java.util.ArrayList; public class CustomButton { public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { CustomButtonFrame frame = new CustomButtonFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } }); } public void addActionListener(ActionListener al) { listenerList.add(al); } public void removeActionListener(ActionListener al) { listenerList.remove(al); } public void actionPerformed(ActionEvent e) { System.out.println("Button Clicked!"); } private void notifyListeners() { ActionEvent event = new ActionEvent(CONFUSED HERE!!!!; for (ActionListener action : listenerList) { action.actionPerfomed(event); } } List<ActionListener> listenerList = new ArrayList<ActionListener>(); } class CustomButtonFrame extends JFrame { // constructor for CustomButtonFrame public CustomButtonFrame() { setTitle("Custom Button"); CustomButtonSetup buttonSetup = new CustomButtonSetup(); this.add(buttonSetup); this.pack(); } } class CustomButtonSetup extends JComponent { public CustomButtonSetup() { ButtonAction buttonClicked = new ButtonAction(); this.addMouseListener(buttonClicked); } // because frame includes borders and insets, use this method public Dimension getPreferredSize() { return new Dimension(200, 200); } public void paintComponent(Graphics g) { Graphics2D g2 = (Graphics2D) g; // first triangle coords int x[] = new int[TRIANGLE_SIDES]; int y[] = new int[TRIANGLE_SIDES]; x[0] = 0; y[0] = 0; x[1] = 200; y[1] = 0; x[2] = 0; y[2] = 200; Polygon firstTriangle = new Polygon(x, y, TRIANGLE_SIDES); // second triangle coords x[0] = 0; y[0] = 200; x[1] = 200; y[1] = 200; x[2] = 200; y[2] = 0; Polygon secondTriangle = new Polygon(x, y, TRIANGLE_SIDES); g2.drawPolygon(firstTriangle); g2.setColor(firstColor); g2.fillPolygon(firstTriangle); g2.drawPolygon(secondTriangle); g2.setColor(secondColor); g2.fillPolygon(secondTriangle); // draw rectangle 10 pixels off border int s1[] = new int[RECT_SIDES]; int s2[] = new int[RECT_SIDES]; s1[0] = 5; s2[0] = 5; s1[1] = 195; s2[1] = 5; s1[2] = 195; s2[2] = 195; s1[3] = 5; s2[3] = 195; Polygon rectangle = new Polygon(s1, s2, RECT_SIDES); g2.drawPolygon(rectangle); g2.setColor(thirdColor); g2.fillPolygon(rectangle); } private class ButtonAction implements MouseListener { public void mousePressed(MouseEvent e) { System.out.println("Click!"); firstColor = Color.GRAY; secondColor = Color.WHITE; repaint(); } public void mouseReleased(MouseEvent e) { System.out.println("Released!"); firstColor = Color.WHITE; secondColor = Color.GRAY; repaint(); } public void mouseEntered(MouseEvent e) {} public void mouseExited(MouseEvent e) {} public void mouseClicked(MouseEvent e) {} } public static final int TRIANGLE_SIDES = 3; public static final int RECT_SIDES = 4; private Color firstColor = Color.WHITE; private Color secondColor = Color.DARK_GRAY; private Color thirdColor = Color.LIGHT_GRAY; }

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• designing database tables using JDBC

  - by Noona

  I am creating a users table using JDBC and mysql, each user has a permissions list that comprises Integer values, I am wondering if I should use an array for storing these values and then have only 1 record for this user in the table, or simply create a new table that comprises 2 columns: user ID and permissions, and then have multiple records for each user that specify the user name in one columns and one permission value in the second column, the second option seems to be redundant since a permission value is a simple object that isn't associated with any other objects (like a student and courses list for example, because the course is associated with many other objects, like grade, teacher, etc, so in this case it is natural to have multiple records), but the first one seems to be a bit unnatural to me, so if someone has experience with these things and direct me? thanks

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• Are there any modern GUI toolkits which implement a heirarchical menu buffer zone?

  - by scomar

  In Bruce Tognazzini's quiz on Fitt's Law, the question discussing the bottleneck in the hierarchical menu (as used in almost every modern desktop UI), talks about his design for the original Mac: The bottleneck is the passage between the first-level menu and the second-level menu. Users first slide the mouse pointer down to the category menu item. Then, they must carefully slide the mouse directly across (horizontally) in order to move the pointer into the secondary menu. The engineer who originally designed hierarchicals apparently had his forearm mounted on a track so that he could move it perfectly in a horizontal direction without any vertical component. Most of us, however, have our forarms mounted on a pivot we like to call our elbow. That means that moving our hand describes an arc, rather than a straight line. Demanding that pivoted people move a mouse pointer along in a straight line horizontally is just wrong. We are naturally going to slip downward even as we try to slide sideways. When we are not allowed to slip downward, the menu we're after is going to slam shut just before we get there. The Windows folks tried to overcome the pivot problem with a hack: If they see the user move down into range of the next item on the primary menu, they don't instantly close the second-level menu. Instead, they leave it open for around a half second, so, if users are really quick, they can be inaccurate but still get into the second-level menu before it slams shut. Unfortunately, people's reactions to heightened chance of error is to slow down, rather than speed up, a well-established phenomenon. Therefore, few users will ever figure out that moving faster could solve their problem. Microsoft's solution is exactly wrong. When I specified the Mac hierarchical menu algorthm in the mid-'80s, I called for a buffer zone shaped like a <, so that users could make an increasingly-greater error as they neared the hierarchical without fear of jumping to an unwanted menu. As long as the user's pointer was moving a few pixels over for every one down, on average, the menu stayed open, no matter how slow they moved. (Cancelling was still really easy; just deliberately move up or down.) This just blew me away! Such a simple idea which would result in a huge improvement in usability. I'm sure I'm not the only one who regularly has the next level of a menu slam shut because I don't move the mouse pointer in a perfectly horizontal line. So my question is: Are there any modern UI toolkits which implement this brilliant idea of a < shaped buffer zone in hierarchical menus? And if not, why not?!

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• What can you do in the ant Task.init() method?

  - by skiphoppy

  I'm developing a few custom ant tasks that all need to initialize the same objects. I wanted to initialize those object's in a common superclass that extends from Task, in the init() method. But I see from the lifecycle of an ant task that init() gets called before the tasks child elements and attributes are set. So all of the data I need for initializing those objects is unavailable during init(), if I am reading right. So, why is init() called at this point? What do you even know that you could use in init()? What could it be used for? (And is there some other method that I can rely on to be called before execute(), but after my data is available?)

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• Many-to-one relationship in SQLAlchemy

  - by Arrieta

  This is a beginner-level question. I have a catalog of mtypes: mtype_id name 1 'mtype1' 2 'mtype2' [etc] and a catalog of Objects, which must have an associated mtype: obj_id mtype_id name 1 1 'obj1' 2 1 'obj2' 3 2 'obj3' [etc] I am trying to do this in SQLAlchemy by creating the following schemas: mtypes_table = Table('mtypes', metadata, Column('mtype_id', Integer, primary_key=True), Column('name', String(50), nullable=False, unique=True), ) objs_table = Table('objects', metadata, Column('obj_id', Integer, primary_key=True), Column('mtype_id', None, ForeignKey('mtypes.mtype_id')), Column('name', String(50), nullable=False, unique=True), ) mapper(MType, mtypes_table) mapper(MyObject, objs_table, properties={'mtype':Relationship(MType, backref='objs', cascade="all, delete-orphan")} ) When I try to add a simple element like: mtype1 = MType('mtype1') obj1 = MyObject('obj1') obj1.mtype=mtype1 session.add(obj1) I get the error: AttributeError: 'NoneType' object has no attribute 'cascade_iterator' Any ideas?

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• how to make objects globally accessible?

  - by fayer

  i have this code: class IC_Core { /** * Database * @var IC_Database */ public static $db = NULL; /** * Core * @var IC_Core */ protected static $_instance = NULL; private function __construct() { } public static function getInstance() { if ( ! is_object(self::$_instance)) { self::$_instance = new self(); self::initialize(self::$_instance); } return self::$_instance; } private static function initialize(IC_Core $IC_Core) { self::$db = new IC_Database($IC_Core); } } but when i wanna access IC_Database with: $IC = IC_Core::getInstance(); $IC->db->add() // it says that its not an object. i think the problem lies in self::$db = new IC_Database($IC_Core); but i dont know how to make it work. could someone give me a hand=) thanks!

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• how to avoid temporaries when copying weakly typed object

  - by Truncheon

  Hi. I'm writing a series classes that inherit from a base class using virtual. They are INT, FLOAT and STRING objects that I want to use in a scripting language. I'm trying to implement weak typing, but I don't want STRING objects to return copies of themselves when used in the following way (instead I would prefer to have a reference returned which can be used in copying): a = "hello "; b = "world"; c = a + b; I have written the following code as a mock example: #include <iostream> #include <string> #include <cstdio> #include <cstdlib> std::string dummy("<int object cannot return string reference>"); struct BaseImpl { virtual bool is_string() = 0; virtual int get_int() = 0; virtual std::string get_string_copy() = 0; virtual std::string const& get_string_ref() = 0; }; struct INT : BaseImpl { int value; INT(int i = 0) : value(i) { std::cout << "constructor called\n"; } INT(BaseImpl& that) : value(that.get_int()) { std::cout << "copy constructor called\n"; } bool is_string() { return false; } int get_int() { return value; } std::string get_string_copy() { char buf[33]; sprintf(buf, "%i", value); return buf; } std::string const& get_string_ref() { return dummy; } }; struct STRING : BaseImpl { std::string value; STRING(std::string s = "") : value(s) { std::cout << "constructor called\n"; } STRING(BaseImpl& that) { if (that.is_string()) value = that.get_string_ref(); else value = that.get_string_copy(); std::cout << "copy constructor called\n"; } bool is_string() { return true; } int get_int() { return atoi(value.c_str()); } std::string get_string_copy() { return value; } std::string const& get_string_ref() { return value; } }; struct Base { BaseImpl* impl; Base(BaseImpl* p = 0) : impl(p) {} ~Base() { delete impl; } }; int main() { Base b1(new INT(1)); Base b2(new STRING("Hello world")); Base b3(new INT(*b1.impl)); Base b4(new STRING(*b2.impl)); std::cout << "\n"; std::cout << b1.impl->get_int() << "\n"; std::cout << b2.impl->get_int() << "\n"; std::cout << b3.impl->get_int() << "\n"; std::cout << b4.impl->get_int() << "\n"; std::cout << "\n"; std::cout << b1.impl->get_string_ref() << "\n"; std::cout << b2.impl->get_string_ref() << "\n"; std::cout << b3.impl->get_string_ref() << "\n"; std::cout << b4.impl->get_string_ref() << "\n"; std::cout << "\n"; std::cout << b1.impl->get_string_copy() << "\n"; std::cout << b2.impl->get_string_copy() << "\n"; std::cout << b3.impl->get_string_copy() << "\n"; std::cout << b4.impl->get_string_copy() << "\n"; return 0; } It was necessary to add an if check in the STRING class to determine whether its safe to request a reference instead of a copy: Script code: a = "test"; b = a; c = 1; d = "" + c; /* not safe to request reference by standard */ C++ code: STRING(BaseImpl& that) { if (that.is_string()) value = that.get_string_ref(); else value = that.get_string_copy(); std::cout << "copy constructor called\n"; } If was hoping there's a way of moving that if check into compile time, rather than run time.

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• 3D Mesh Joining

  - by morlst

  I have 2 (or more) intersecting meshes, which require joining into 1 mesh object. I want to have some control over the resulting seam vertex insertion, so looking to write myself rather than use a library. Has anyone come across some open source code to base the algorithm on / ideas on the process? Initial impressions are: 1. Present in every 3D modelling program - mostly reinventing existing process (hence search for examples) 2. Potential for fiddly-ness around the polygon face direction and just touching conditions. (see above point)

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• How to write this in better way?

  - by dario

  Hi all. Let's look at this code: IList<IHouseAnnouncement> list = new List<IHouseAnnouncement>(); var table = adapter.GetData(); //get data from repository object -> DataTable if (table.Rows.Count >= 1) { for (int i = 0; i < table.Rows.Count-1; i++) { var anno = new HouseAnnouncement(); anno.Area = float.Parse(table.Rows[i][table.powierzchniaColumn].ToString()); anno.City = table.Rows[i][table.miastoColumn].ToString(); list.Add(anno); } } return list; Is it better way to write this in less code and better fashion (must be :-) )? Maybe using labda (but let mi know how)? Thanks in advance!

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• How can I get a property as an Entity in Action of Asp.Net Mvc ?

  - by Felipe

  Hi all, i'd like to know how can I get a property like an entity, for example: My Model: public class Product { public int Id { get; set; } public string Name { get; set; } public Category Category { get; set; } } View: Name: <%=Html.TextBoxFor(x => x.Name) %> Category: <%= Html.DropDownList("Category", IEnumerable<SelectListItem>)ViewData["Categories"]) %> Controller: public ActionResult Save(Product product) { /// produtct.Category ??? } and how is the category property ? It's fill by the view ? ASP.Net MVC know how to fill this object by ID ? Thanks!

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• How to model a relationship that NHibernate (or Hibernate) doesn’t easily support

  - by MylesRip

  I have a situation in which the ideal relationship, I believe, would involve Value Object Inheritance. This is unfortunately not supported in NHibernate so any solution I come up with will be less than perfect. Let’s say that: “Item” entities have a “Location” that can be in one of multiple different formats. These formats are completely different with no overlapping fields. We will deal with each Location in the format that is provided in the data with no attempt to convert from one format to another. Each Item has exactly one Location. “SpecialItem” is a subtype of Item, however, that is unique in that it has exactly two Locations. “Group” entities aggregate Items. “LocationGroup” is as subtype of Group. LocationGroup also has a single Location that can be in any of the formats as described above. Although I’m interested in Items by Group, I’m also interested in being able to find all items with the same Location, regardless of which group they are in. I apologize for the number of stipulations listed above, but I’m afraid that simplifying it any further wouldn’t really reflect the difficulties of the situation. Here is how the above could be diagrammed: Mapping Dilemma Diagram: (http://www.freeimagehosting.net/uploads/592ad48b1a.jpg) (I tried placing the diagram inline, but Stack Overflow won't allow that until I have accumulated more points. I understand the reasoning behind it, but it is a bit inconvenient for now.) Hmmm... Apparently I can't have multiple links either. :-( Analyzing the above, I make the following observations: I treat Locations polymorphically, referring to the supertype rather than the subtype. Logically, Locations should be “Value Objects” rather than entities since it is meaningless to differentiate between two Location objects that have all the same values. Thus equality between Locations should be based on field comparisons, not identifiers. Also, value objects should be immutable and shared references should not be allowed. Using NHibernate (or Hibernate) one would typically map value objects using the “component” keyword which would cause the fields of the class to be mapped directly into the database table that represents the containing class. Put another way, there would not be a separate “Locations” table in the database (and Locations would therefore have no identifiers). NHibernate (or Hibernate) do not currently support inheritance for value objects. My choices as I see them are: Ignore the fact that Locations should be value objects and map them as entities. This would take care of the inheritance mapping issues since NHibernate supports entity inheritance. The downside is that I then have to deal with aliasing issues. (Meaning that if multiple objects share a reference to the same Location, then changing values for one object’s Location would cause the location to change for other objects that share the reference the same Location record.) I want to avoid this if possible. Another downside is that entities are typically compared by their IDs. This would mean that two Location objects would be considered not equal even if the values of all their fields are the same. This would be invalid and unacceptable from the business perspective. Flatten Locations into a single class so that there are no longer inheritance relationships for Locations. This would allow Locations to be treated as value objects which could easily be handled by using “component” mapping in NHibernate. The downside in this case would be that the domain model becomes weaker, more fragile and less maintainable. Do some “creative” mapping in the hbm files in order to force Location fields to be mapped into the containing entities’ tables without using the “component” keyword. This approach is described by Colin Jack here. My situation is more complicated than the one he describes due to the fact that SpecialItem has a second Location and the fact that a different entity, LocatedGroup, also has Locations. I could probably get it to work, but the mappings would be non-intuitive and therefore hard to understand and maintain by other developers in the future. Also, I suspect that these tricky mappings would likely not be possible using Fluent NHibernate so I would use the advantages of using that tool, at least in that situation. Surely others out there have run into similar situations. I’m hoping someone who has “been there, done that” can share some wisdom. :-) So here’s the question… Which approach should be preferred in this situation? Why?

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• Makefile: expand dependencies

  - by Danyel

  First off, the title is very generic because there are just tons of ways of how to possibly solve this. However, I'm looking for a clean and neat way. Situation: I have two equal object files foo.o and foo-pi.o, the latter of which is position-independent (compiled with -fPIC). Both depend on foo.h and bar.h. Problem: How do I, without code duplication, declare dependency of all foo*.o to bar.h? Solutions so far: $(shell bash -c 'echo -ne foo{-pi,}.o'}: bar.h $(addsuffix .o, $(addprefix fo, o-pi o)): bar.h The first solution is not portable on systems that don't support bash, the second is a dirty solution since I could not figure out how to use empty strings in addprefix.

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• How to map one class against multiple tables with SQLAlchemy?

  - by tote

  Lets say that I have a database structure with three tables that look like this: items - item_id - item_handle attributes - attribute_id - attribute_name item_attributes - item_attribute_id - item_id - attribute_id - attribute_value I would like to be able to do this in SQLAlchemy: item = Item('item1') item.foo = 'bar' session.add(item) session.commit() item1 = session.query(Item).filter_by(handle='item1').one() print item1.foo # => 'bar' I'm new to SQLAlchemy and I found this in the documentation (http://www.sqlalchemy.org/docs/05/mappers.html#mapping-a-class-against-multiple-tables): j = join(items, item_attributes, items.c.item_id == item_attributes.c.item_id). \ join(attributes, item_attributes.c.attribute_id == attributes.c.attribute_id) mapper(Item, j, properties={ 'item_id': [items.c.item_id, item_attributes.c.item_id], 'attribute_id': [item_attributes.c.attribute_id, attributes.c.attribute_id], }) It only adds item_id and attribute_id to Item and its not possible to add attributes to Item object. Is what I'm trying to achieve possible with SQLAlchemy? Is there a better way to structure the database to get the same behaviour of "dynamic columns"?

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• JSON object array to store data of a form in local storage temporary (PhoneGap project)

  - by Nadeesha

  I am building a data aqusition system using PhoneGap. .I am trying to store my form data temporary on local storage using JSON,Data should be visible after I close and reopen the application (after pressing Get Data button),But after I close it only the lastly entered record is visible This is my code <!DOCTYPE html> <html> <head> <title>Household Profile DB storage</title> <meta charset="utf-8"> <meta name="viewport" content="user-scalable=no, initial-scale=1, maximum-scale=1, minimum-scale=1,width=device-width" /> <link rel="stylesheet" href="jquery.mobile-1.4.2/jquery.mobile-1.4.2.min.css"> <link rel="stylesheet" href="css/table.css"> <script type="text/javascript" src="js/jquery-1.9.1.min.js"></script> <script type="text/javascript" src="jquery.mobile-1.4.2/jquery.mobile-1.4.2.min.js"></script> <script type="text/javascript" src="js/iscroll.js"></script> <script type="text/javascript" charset="utf-8"> function onDeviceReady() { persistData(homeId,owner,gramaND,contactNo,address,race); } function saveLocal(form){ if (window.localStorage) { var fhomeId = form.homeId.value, fowner = form.owner.value, fgramaND = form.gramaND.value, fcontactNo= form.contactNo.value, faddress = form.address.value, frace = form.race.value; alert("hi"); var highscores = [{"homeId": fhomeId, "owner":fowner, "gramaND":fgramaND, "contactNo":fcontactNo, "address":faddress, "race":frace}]; localStorage.setItem("highscores",JSON.stringify(highscores)); alert("The data has been stored successfully."); } else { alert("Your Browser does not support LocalStorage."); } } function readLocal(){ if (window.localStorage) { var scores =[]; //Get the highscores object scores = localStorage.getItem("highscores"); scores = JSON.parse(scores); for (i=0;i<scores.length;i++){ var text = "homeId :"+scores[i].homeId +"<br>"+ "owner:"+ scores[i].owner+"<br>"+ "address"+scores[i].address +"<br>"+ "gramaND"+scores[i].gramaND +"<br>"+ "contactNo"+scores[i].contactNo+"<br>" + '<Button value="DELETE" onclick="'+scores.splice(i, 0)+'><>/Button>'; var tbodyx = document.getElementsByTagName("tbody"); var tr=document.createElement("TR"); var td=document.createElement("TD"); td.innerHTML = text; tr.appendChild(td); tbody.appendChild(tr); } } } </script> </head> <body> <div data-role="page" id="page1"> <!--/header--> <div data-role="header" data-position="inline" data-theme="b"> <a href="#" data-icon="back" data-rel="back" title="Go back">Back</a> <h1>Household Profile</h1> <a href="index.html" data-icon="home">Menu</a> </div> <!--/header--> <div id="wrapper"> <form id="userInput" action ="" method="GET"> <div data-role="content"> <div data-role="fieldcontain"> <label > Home ID </label> <input class="inputClass" id="homeId" placeholder="H0001" value="" data-mini="true" type="text"> </div> <div data-role="fieldcontain"> <label > Owner </label> <input class="inputClass" id="owner" placeholder="Aberathne" value="" type="text"> </div> <div data-role="fieldcontain"> <label class="select">GramaNiladhari Division</label> <select class="inputClass" id="gramaND"> <option value="GramaNiladhari Division 1">GramaNiladhari Division 1</option> <option value="GramaNiladhari Division 2">GramaNiladhari Division 2</option> <option value="GramaNiladhari Division 3">GramaNiladhari Division 3</option> <option value="GramaNiladhari Division 4">GramaNiladhari Division 4</option> </select> </div> <div data-role="fieldcontain"> <label > Contact No </label> <input class="inputClass" id="contactNo" placeholder="071-9545-073" value="" type="number"> </div> <div data-role="fieldcontain"> <label >Address:</label> <textarea cols="40" rows="8" class="inputClass" id="address"></textarea> </div> <div class="ui-block-a"><button type="submit" data-theme="d">Location in a Map</button></div> <div data-role="fieldcontain"> <label >Race</label> <select class="inputClass" id="race"> <option value=" Sinhalese"> Sinhalese</option> <option value=" Sri Lanka Tamils"> Sri Lanka Tamils</option> <option value=" Moors"> Moors</option> <option value=" Indian Tamils "> Indian Tamils </option> <option value=" Malays "> Malays </option> <option value=" Burghers "> Burghers </option> </select> </div> <input class="buttonClass" type="button" value="Insert Data" onclick="saveLocal(this.form);"> </div> </form> </div> <input class="buttonClass" type="button" value="get Data" onclick="readLocal();"> <!-- <p id="dhomeId"></p> <p id="downer"></p> <p id="dgramaND"></p> <p id="dcontactNo"></p> <p id="daddress"></p> <p id="drace"></p>--> <table border="1"> <tbody id="tbody"> <tr><td>test1</td></tr> <tr><td>test2</td></tr> </tbody> </table> </div> </body> </html> Also I need to expand my code to edit and delete record from local storage.

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• RuntimeError: maximum recursion depth exceeded while calling a Python object

  - by Bilal Basharat

  this error arises when i try to run the following test case which is written in models.py of my django app named 'administration' : from django.test import Client, TestCase from django.core import mail class ClientTest( TestCase ): fixtures = [ 'testdata.json' ] def test_get_register( self ): response = self.client.get( '/accounts/register/', {} ) self.assertEqual( response.status_code, 200 ) the error arises at this line specifically: response = self.client.get( '/accounts/register/', {} ) my django version is 1.2.1 and python 2.6 and satchmo version is 0.9.2-pre hg-unknown. I code in windows platform(xp sp2). The command to run test case is: python manage.py test administration the complete error log is as follow: site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 101, in by_host site = Site.objects.get(domain=host) File "C:\django\django\db\models\manager.py", line 132, in get return self.get_query_set().get(*args, **kwargs) File "C:\django\django\db\models\query.py", line 336, in get num = len(clone) File "C:\django\django\db\models\query.py", line 81, in __len__ self._result_cache = list(self.iterator()) File "C:\django\django\db\models\query.py", line 269, in iterator for row in compiler.results_iter(): File "C:\django\django\db\models\sql\compiler.py", line 672, in results_iter for rows in self.execute_sql(MULTI): File "C:\django\django\db\models\sql\compiler.py", line 717, in execute_sql sql, params = self.as_sql() File "C:\django\django\db\models\sql\compiler.py", line 65, in as_sql where, w_params = self.query.where.as_sql(qn=qn, connection=self.connection) File "C:\django\django\db\models\sql\where.py", line 91, in as_sql sql, params = child.as_sql(qn=qn, connection=connection) File "C:\django\django\db\models\sql\where.py", line 94, in as_sql sql, params = self.make_atom(child, qn, connection) File "C:\django\django\db\models\sql\where.py", line 141, in make_atom lvalue, params = lvalue.process(lookup_type, params_or_value, connection) File "C:\django\django\db\models\sql\where.py", line 312, in process connection=connection, prepared=True) File "C:\django\django\db\models\fields\subclassing.py", line 53, in inner return func(*args, **kwargs) File "C:\django\django\db\models\fields\subclassing.py", line 53, in inner return func(*args, **kwargs) File "C:\django\django\db\models\fields\__init__.py", line 323, in get_db_prep _lookup return [self.get_db_prep_value(value, connection=connection, prepared=prepar ed)] File "C:\django\django\db\models\fields\subclassing.py", line 53, in inner return func(*args, **kwargs) File "C:\django\django\db\models\fields\subclassing.py", line 53, in inner return func(*args, **kwargs) RuntimeError: maximum recursion depth exceeded while calling a Python object ---------------------------------------------------------------------- Ran 7 tests in 48.453s FAILED (errors=1) Destroying test database 'default'...

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• Contructor parameters for dependent classes with Unity Framework

  - by Onisemus

  I just started using the Unity Application Block to try to decouple my classes and make it easier for unit testing. I ran into a problem though that I'm not sure how to get around. Looked through the documentation and did some Googling but I'm coming up dry. Here's the situation: I have a facade-type class which is a chat bot. It is a singleton class which handles all sort of secondary classes and provides a central place to launch and configure the bot. I also have a class called AccessManager which, well, manages access to bot commands and resources. Boiled down to the essence, I have the classes set up like so. public class Bot { public string Owner { get; private set; } public string WorkingDirectory { get; private set; } private IAccessManager AccessManager; private Bot() { // do some setup // LoadConfig sets the Owner & WorkingDirectory variables LoadConfig(); // init the access mmanager AccessManager = new MyAccessManager(this); } public static Bot Instance() { // singleton code } ... } And the AccessManager class: public class MyAccessManager : IAccessManager { private Bot botReference; public MyAccesManager(Bot botReference) { this.botReference = botReference; SetOwnerAccess(botReference.Owner); } private void LoadConfig() { string configPath = Path.Combine( botReference.WorkingDirectory, "access.config"); // do stuff to read from config file } ... } I would like to change this design to use the Unity Application Block. I'd like to use Unity to generate the Bot singleton and to load the AccessManager interface in some sort of bootstrapping method that runs before anything else does. public static void BootStrapSystem() { IUnityContainer container = new UnityContainer(); // create new bot instance Bot newBot = Bot.Instance(); // register bot instance container.RegisterInstance<Bot>(newBot); // register access manager container.RegisterType<IAccessManager,MyAccessManager>(newBot); } And when I want to get a reference to the Access Manager inside the Bot constructor I can just do: IAcessManager accessManager = container.Resolve<IAccessManager>(); And elsewhere in the system to get a reference to the Bot singleton: // do this Bot botInstance = container.Resolve<Bot>(); // instead of this Bot botInstance = Bot.Instance(); The problem is the method BootStrapSystem() is going to blow up. When I create a bot instance it's going to try to resolve IAccessManager but won't be able to because I haven't registered the types yet (that's the next line). But I can't move the registration in front of the Bot creation because as part of the registration I need to pass the Bot as a parameter! Circular dependencies!! Gah!!! This indicates to me I have a flaw in the way I have this structured. But how do I fix it? Help!!

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• Domain Validation in a CQRS architecture

  - by Jupaol

  Basically I want to know if there is a better way to validate my domain entities. This is how I am planning to do it but I would like your opinion The first approach I considered was: class Customer : EntityBase<Customer> { public void ChangeEmail(string email) { if(string.IsNullOrWhitespace(email)) throw new DomainException(“...”); if(!email.IsEmail()) throw new DomainException(); if(email.Contains(“@mailinator.com”)) throw new DomainException(); } } I actually do not like this validation because even when I am encapsulating the validation logic in the correct entity, this is violating the Open/Close principle (Open for extension but Close for modification) and I have found that violating this principle, code maintenance becomes a real pain when the application grows up in complexity. Why? Because domain rules change more often than we would like to admit, and if the rules are hidden and embedded in an entity like this, they are hard to test, hard to read, hard to maintain but the real reason why I do not like this approach is: if the validation rules change, I have to come and edit my domain entity. This has been a really simple example but in RL the validation could be more complex So following the philosophy of Udi Dahan, making roles explicit, and the recommendation from Eric Evans in the blue book, the next try was to implement the specification pattern, something like this class EmailDomainIsAllowedSpecification : IDomainSpecification<Customer> { private INotAllowedEmailDomainsResolver invalidEmailDomainsResolver; public bool IsSatisfiedBy(Customer customer) { return !this.invalidEmailDomainsResolver.GetInvalidEmailDomains().Contains(customer.Email); } } But then I realize that in order to follow this approach I had to mutate my entities first in order to pass the value being valdiated, in this case the email, but mutating them would cause my domain events being fired which I wouldn’t like to happen until the new email is valid So after considering these approaches, I came out with this one, since I am going to implement a CQRS architecture: class EmailDomainIsAllowedValidator : IDomainInvariantValidator<Customer, ChangeEmailCommand> { public void IsValid(Customer entity, ChangeEmailCommand command) { if(!command.Email.HasValidDomain()) throw new DomainException(“...”); } } Well that’s the main idea, the entity is passed to the validator in case we need some value from the entity to perform the validation, the command contains the data coming from the user and since the validators are considered injectable objects they could have external dependencies injected if the validation requires it. Now the dilemma, I am happy with a design like this because my validation is encapsulated in individual objects which brings many advantages: easy unit test, easy to maintain, domain invariants are explicitly expressed using the Ubiquitous Language, easy to extend, validation logic is centralized and validators can be used together to enforce complex domain rules. And even when I know I am placing the validation of my entities outside of them (You could argue a code smell - Anemic Domain) but I think the trade-off is acceptable But there is one thing that I have not figured out how to implement it in a clean way. How should I use this components... Since they will be injected, they won’t fit naturally inside my domain entities, so basically I see two options: Pass the validators to each method of my entity Validate my objects externally (from the command handler) I am not happy with the option 1 so I would explain how I would do it with the option 2 class ChangeEmailCommandHandler : ICommandHandler<ChangeEmailCommand> { public void Execute(ChangeEmailCommand command) { private IEnumerable<IDomainInvariantValidator> validators; // here I would get the validators required for this command injected, and in here I would validate them, something like this using (var t = this.unitOfWork.BeginTransaction()) { var customer = this.unitOfWork.Get<Customer>(command.CustomerId); this.validators.ForEach(x =. x.IsValid(customer, command)); // here I know the command is valid // the call to ChangeEmail will fire domain events as needed customer.ChangeEmail(command.Email); t.Commit(); } } } Well this is it. Can you give me your thoughts about this or share your experiences with Domain entities validation EDIT I think it is not clear from my question, but the real problem is: Hiding the domain rules has serious implications in the future maintainability of the application, and also domain rules change often during the life-cycle of the app. Hence implementing them with this in mind would let us extend them easily. Now imagine in the future a rules engine is implemented, if the rules are encapsulated outside of the domain entities, this change would be easier to implement

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• How to generate a Program template by generating an abstract class

  - by Byron-Lim Timothy Steffan

  i have the following problem. The 1st step is to implement a program, which follows a specific protocol on startup. Therefore, functions as onInit, onConfigRequest, etc. will be necessary. (These are triggered e.g. by incoming message on a TCP Port) My goal is to generate a class for example abstract one, which has abstract functions as onInit(), etc. A programmer should just inherit from this base class and should merely override these abstract functions of the base class. The rest as of the protocol e.g. should be simply handled in the background (using the code of the base class) and should not need to appear in the programmers code. What is the correct design strategy for such tasks? and how do I deal with, that the static main method is not inheritable? What are the key-tags for this problem? (I have problem searching for a solution since I lack clear statements on this problem) Goal is to create some sort of library/class, which - included in ones code - results in executables following the protocol. EDIT (new explanation): Okay let me try to explain more detailled: In this case programs should be clients within a client server architecture. We have a client server connection via TCP/IP. Each program needs to follow a specific protocol upon program start: As soon as my program starts and gets connected to the server it will receive an Init Message (TcpClient), when this happens it should trigger the function onInit(). (Should this be implemented by an event system?) After onInit() a acknowledgement message should be sent to the server. Afterwards there are some other steps as e.g. a config message from the server which triggers an onConfig and so on. Let's concentrate on the onInit function. The idea is, that onInit (and onConfig and so on) should be the only functions the programmer should edit while the overall protocol messaging is hidden for him. Therefore, I thought using an abstract class with the abstract methods onInit(), onConfig() in it should be the right thing. The static Main class I would like to hide, since within it e.g. there will be some part which connects to the tcp port, which reacts on the Init Message and which will call the onInit function. 2 problems here: 1. the static main class cant be inherited, isn it? 2. I cannot call abstract functions from the main class in the abstract master class. Let me give an Pseudo-example for my ideas: public abstract class MasterClass { static void Main(string[] args){ 1. open TCP connection 2. waiting for Init Message from server 3. onInit(); 4. Send Acknowledgement, that Init Routine has ended successfully 5. waiting for Config message from server 6..... } public abstract void onInit(); public abstract void onConfig(); } I hope you get the idea now! The programmer should afterwards inherit from this masterclass and merely need to edit the functions onInit and so on. Is this way possible? How? What else do you recommend for solving this? EDIT: The strategy ideo provided below is a good one! Check out my comment on that.

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• Advice on Factory Method

  - by heath

  Using php 5.2, I'm trying to use a factory to return a service to the controller. My request uri would be of the format www.mydomain.com/service/method/param1/param2/etc. My controller would then call a service factory using the token sent in the uri. From what I've seen, there are two main routes I could go with my factory. Single method: class ServiceFactory { public static function getInstance($token) { switch($token) { case 'location': return new StaticPageTemplateService('location'); break; case 'product': return new DynamicPageTemplateService('product'); break; case 'user' return new UserService(); break; default: return new StaticPageTemplateService($token); } } } or multiple methods: class ServiceFactory { public static function getLocationService() { return new StaticPageTemplateService('location'); } public static function getProductService() { return new DynamicPageTemplateService('product'); } public static function getUserService() { return new UserService(); } public static function getDefaultService($token) { return new StaticPageTemplateService($token); } } So, given this, I will have a handful of generic services in which I will pass that token (for example, StaticPageTemplateService and DynamicPageTemplateService) that will probably implement another factory method just like this to grab templates, domain objects, etc. And some that will be specific services (for example, UserService) which will be 1:1 to that token and not reused. So, this seems to be an ok approach (please give suggestions if it is not) for a small amount of services. But what about when, over time and my site grows, I end up with 100s of possibilities. This no longer seems like a good approach. Am I just way off to begin with or is there another design pattern that would be a better fit? Thanks. UPDATE: @JSprang - the token is actually sent in the uri like mydomain.com/location would want a service specific to loction and mydomain.com/news would want a service specific to news. Now, for a lot of these, the service will be generic. For instance, a lot of pages will call a StaticTemplatePageService in which the token is passed in to the service. That service in turn will grab the "location" template or "links" template and just spit it back out. Some will need DynamicTemplatePageService in which the token gets passed in, like "news" and that service will grab a NewsDomainObject, determine how to present it and spit that back out. Others, like "user" will be specific to a UserService in which it will have methods like Login, Logout, etc. So basically, the token will be used to determine which service is needed AND if it is generic service, that token will be passed to that service. Maybe token isn't the correct terminology but I hope you get the purpose. I wanted to use the factory so I can easily swap out which Service I need in case my needs change. I just worry that after the site grows larger (both pages and functionality) that the factory will become rather bloated. But I'm starting to feel like I just can't get away from storing the mappings in an array (like Stephen's solution). That just doesn't feel OOP to me and I was hoping to find something more elegant.

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• What does a WinForm application need to be designed for usability, and be robust, clean, and profess

  - by msorens

  One of the principal problems impeding productivity in software implementation is the classic conundrum of “reinventing the wheel”. Of late I am a .NET developer and even the wonderful wizardry of .NET and Visual Studio covers only a portion of this challenging issue. Below I present my initial thoughts both on what is available and what should be available from .NET on a WinForm, focusing on good usability. That is, aspects of an application exposed to the user and making the user experience easier and/or better. (I do include a couple items not visible to the user because I feel strongly about them, such as diagnostics.) I invite you to contribute to these lists. LIST A: Components provided by .NET These are substantially complete components provided by .NET, i.e. those requiring at most trivial coding to use. “About” dialog -- add it with a couple clicks then customize. Persist settings across invocations -- .NET has the support; just use a few lines of code to glue them together. Migrate settings with a new version -- a powerful one, available with one line of code. Tooltips (and infotips) -- .NET includes just plain text tooltips; third-party libraries provide richer ones. Diagnostic support -- TraceSources, TraceListeners, and more are built-in. Internationalization -- support for tailoring your app to languages other than your own. LIST B: Components not provided by .NET These are not supplied at all by .NET or supplied only as rudimentary elements requiring substantial work to be realized. Splash screen -- a small window present during program startup with your logo, loading messages, etc. Tip of the day -- a mini-tutorial presented one bit at a time each time the user starts your app. Check for available updates -- facility to query a server to see if the user is running the latest version of your app, then provide a simple way to upgrade if a new version is found. Maximize to multiple monitors -- the canonical window allows you to maximize to a single monitor only; in my apps I allow maximizing across multiple monitors with a click. Taskbar notifier -- flash the taskbar when your backgrounded app has new info for the user. Options dialogs -- multi-page dialogs letting the user customize the app settings to his/her own preferences. Progress indicator -- for long running operations give the user feedback on how far there is left to go. Memory gauge -- an indicator (either absolute or percentage) of how much memory is used by your app. LIST C: Stylistic and/or tiny bits of functionality This list includes bits of functionality that are too tiny to merit being called a component, along with stylistic concerns (that admittedly do overlap with the Windows User Experience Interaction Guidelines). Design a form for resizing -- unless you are restricting your form to be a fixed size, use anchors and docking so that it does what is reasonable when enlarged or shrunk by the user. Set tab order on a form -- repeated tab presses by the user should advance from field to field in a logical order rather than the default order in which you added fields. Adjust controls to be aware of operating modes -- When starting a background operation with, for example, a “Go” button, disable that “Go” button until the operation completes. Provide access keys for all menu items (per UXGuide). Provide shortcut keys for commonly used menu items (per UXGuide). Set up some (global or important or common) shortcut keys without associating to menu items. Allow some menu items to be invoked with or without modifier keys (shift, control, alt) where the modifier key is useful to vary the operation slightly. Hook up Escape and Enter on child forms to do what is reasonable. Decorate any library classes with documentation-comments and attributes -- this allows Visual Studio to leverage them for Intellisense and property descriptions. Spell check your code! What else would you include?

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• referencing part of the composite primary key

  - by Zavael

  I have problems with setting the reference on database table. I have following structure: CREATE TABLE club( id INTEGER NOT NULL, name_short VARCHAR(30), name_full VARCHAR(70) NOT NULL ); CREATE UNIQUE INDEX club_uix ON club(id); ALTER TABLE club ADD CONSTRAINT club_pk PRIMARY KEY (id); CREATE TABLE team( id INTEGER NOT NULL, club_id INTEGER NOT NULL, team_name VARCHAR(30) ); CREATE UNIQUE INDEX team_uix ON team(id, club_id); ALTER TABLE team ADD CONSTRAINT team_pk PRIMARY KEY (id, club_id); ALTER TABLE team ADD FOREIGN KEY (club_id) REFERENCES club(id); CREATE TABLE person( id INTEGER NOT NULL, first_name VARCHAR(20), last_name VARCHAR(20) NOT NULL ); CREATE UNIQUE INDEX person_uix ON person(id); ALTER TABLE person ADD PRIMARY KEY (id); CREATE TABLE contract( person_id INTEGER NOT NULL, club_id INTEGER NOT NULL, wage INTEGER ); CREATE UNIQUE INDEX contract_uix on contract(person_id); ALTER TABLE contract ADD CONSTRAINT contract_pk PRIMARY KEY (person_id); ALTER TABLE contract ADD FOREIGN KEY (club_id) REFERENCES club(id); ALTER TABLE contract ADD FOREIGN KEY (person_id) REFERENCES person(id); CREATE TABLE player( person_id INTEGER NOT NULL, team_id INTEGER, height SMALLINT, weight SMALLINT ); CREATE UNIQUE INDEX player_uix on player(person_id); ALTER TABLE player ADD CONSTRAINT player_pk PRIMARY KEY (person_id); ALTER TABLE player ADD FOREIGN KEY (person_id) REFERENCES person(id); -- ALTER TABLE player ADD FOREIGN KEY (team_id) REFERENCES team(id); --this is not working It gives me this error: Error code -5529, SQL state 42529: a UNIQUE constraint does not exist on referenced columns: TEAM in statement [ALTER TABLE player ADD FOREIGN KEY (team_id) REFERENCES team(id)] As you can see, team table has composite primary key (club_id + id), the person references club through contract. Person has some common attributes for player and other staff types. One club can have multiple teams. Employed person has to have a contract with a club. Player (is the specification of person) - if emplyed - can be assigned to one of the club's teams. Is there better way to design my structure? I thought about excluding the club_id from team's primary key, but I would like to know if this is the only way. Thanks. UPDATE 1 I would like to have the id as team identification only within the club, so multiple teams can have equal id as long as they belong to different clubs. Is it possible? UPDATE 2 updated the naming convention as adviced by philip Some business rules to better understand the structure: One club can have 1..n teams (Main squad, Reserve squad, Youth squad or Team A, Team B... only team can play match, not club) One team belongs to one club only A player is type of person (other types (staff) are scouts, coaches etc so they do not need to belong to specific team, just to the club, if employed) Person can have 0..1 contract with 1 club (that means he is employed or unemployed) Player (if employed) belongs to one team of the club Now thinking about it - moving team_id from player to contract would solve my problem, and it could hold the condition "Player (if employed) belongs to one team of the club", but it would be redundant for other staff types. What do you think?

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• Keeping video viewing statistics breakdown by video time in a database

  - by Septagram

  I need to keep a number of statistics about the videos being watched, and one of them is what parts of the video are being watched most. The design I came up with is to split the video into 256 intervals and keep the floating-point number of views for each of them. I receive the data as a number of intervals the user watched continuously. The problem is how to store them. There are two solutions I see. Row per every video segment Let's have a database table like this: CREATE TABLE `video_heatmap` ( `id` int(11) NOT NULL AUTO_INCREMENT, `video_id` int(11) NOT NULL, `position` tinyint(3) unsigned NOT NULL, `views` float NOT NULL, PRIMARY KEY (`id`), UNIQUE KEY `idx_lookup` (`video_id`,`position`) ) ENGINE=MyISAM Then, whenever we have to process a number of views, make sure there are the respective database rows and add appropriate values to the views column. I found out it's a lot faster if the existence of rows is taken care of first (SELECT COUNT(*) of rows for a given video and INSERT IGNORE if they are lacking), and then a number of update queries is used like this: UPDATE video_heatmap SET views = views + ? WHERE video_id = ? AND position >= ? AND position < ? This seems, however, a little bloated. The other solution I came up with is Row per video, update in transactions A table will look (sort of) like this: CREATE TABLE video ( id INT NOT NULL AUTO_INCREMENT, heatmap BINARY (4 * 256) NOT NULL, ... ) ENGINE=InnoDB Then, upon every time a view needs to be stored, it will be done in a transaction with consistent snapshot, in a sequence like this: If the video doesn't exist in the database, it is created. A row is retrieved, heatmap, an array of floats stored in the binary form, is converted into a form more friendly for processing (in PHP). Values in the array are increased appropriately and the array is converted back. Row is changed via UPDATE query. So far the advantages can be summed up like this: First approach Stores data as floats, not as some magical binary array. Doesn't require transaction support, so doesn't require InnoDB, and we're using MyISAM for everything at the moment, so there won't be any need to mix storage engines. (only applies in my specific situation) Doesn't require a transaction WITH CONSISTENT SNAPSHOT. I don't know what are the performance penalties of those. I already implemented it and it works. (only applies in my specific situation) Second approach Is using a lot less storage space (the first approach is storing video ID 256 times and stores position for every segment of the video, not to mention primary key). Should scale better, because of InnoDB's per-row locking as opposed to MyISAM's table locking. Might generally work faster because there are a lot less requests being made. Easier to implement in code (although the other one is already implemented). So, what should I do? If it wasn't for the rest of our system using MyISAM consistently, I'd go with the second approach, but currently I'm leaning to the first one. But maybe there are some reasons to favour one approach or another?

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• Testing for Adjacent Cells In a Multi-level Grid

  - by Steve

  I'm designing an algorithm to test whether cells on a grid are adjacent or not. The catch is that the cells are not on a flat grid. They are on a multi-level grid such as the one drawn below. Level 1 (Top Level) | - - - - - | | A | B | C | | - - - - - | | D | E | F | | - - - - - | | G | H | I | | - - - - - | Level 2 | -Block A- | -Block B- | | 1 | 2 | 3 | 1 | 2 | 3 | | - - - - - | - - - - - | | 4 | 5 | 6 | 4 | 5 | 6 | ... | - - - - - | - - - - - | | 7 | 8 | 9 | 7 | 8 | 9 | | - - - - - | - - - - - | | -Block D- | -Block E- | | 1 | 2 | 3 | 1 | 2 | 3 | | - - - - - | - - - - - | | 4 | 5 | 6 | 4 | 5 | 6 | ... | - - - - - | - - - - - | | 7 | 8 | 9 | 7 | 8 | 9 | | - - - - - | - - - - - | . . . . . . This diagram is simplified from my actual need but the concept is the same. There is a top level block with many cells within it (level 1). Each block is further subdivided into many more cells (level 2). Those cells are further subdivided into level 3, 4 and 5 for my project but let's just stick to two levels for this question. I'm receiving inputs for my function in the form of "A8, A9, B7, D3". That's a list of cell Ids where each cell Id has the format (level 1 id)(level 2 id). Let's start by comparing just 2 cells, A8 and A9. That's easy because they are in the same block. private static RelativePosition getRelativePositionInTheSameBlock(String v1, String v2) { RelativePosition relativePosition; if( v1-v2 == -1 ) { relativePosition = RelativePosition.LEFT_OF; } else if (v1-v2 == 1) { relativePosition = RelativePosition.RIGHT_OF; } else if (v1-v2 == -BLOCK_WIDTH) { relativePosition = RelativePosition.TOP_OF; } else if (v1-v2 == BLOCK_WIDTH) { relativePosition = RelativePosition.BOTTOM_OF; } else { relativePosition = RelativePosition.NOT_ADJACENT; } return relativePosition; } An A9 - B7 comparison could be done by checking if A is a multiple of BLOCK_WIDTH and whether B is (A-BLOCK_WIDTH+1). Either that or just check naively if the A/B pair is 3-1, 6-4 or 9-7 for better readability. For B7 - D3, they are not adjacent but D3 is adjacent to A9 so I can do a similar adjacency test as above. So getting away from the little details and focusing on the big picture. Is this really the best way to do it? Keeping in mind the following points: I actually have 5 levels not 2, so I could potentially get a list like "A8A1A, A8A1B, B1A2A, B1A2B". Adding a new cell to compare still requires me to compare all the other cells before it (seems like the best I could do for this step is O(n)) The cells aren't all 3x3 blocks, they're just that way for my example. They could be MxN blocks with different M and N for different levels. In my current implementation above, I have separate functions to check adjacency if the cells are in the same blocks, if they are in separate horizontally adjacent blocks or if they are in separate vertically adjacent blocks. That means I have to know the position of the two blocks at the current level before I call one of those functions for the layer below. Judging by the complexity of having to deal with mulitple functions for different edge cases at different levels and having 5 levels of nested if statements. I'm wondering if another design is more suitable. Perhaps a more recursive solution, use of other data structures, or perhaps map the entire multi-level grid to a single-level grid (my quick calculations gives me about 700,000+ atomic cell ids). Even if I go that route, mapping from multi-level to single level is a non-trivial task in itself.

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• &lsquo;Responsive Web Design with Macaw&rsquo;&ndash; free book updated

  - by ihaynes

  Originally posted on: http://geekswithblogs.net/ihaynes/archive/2014/08/12/lsquoresponsive-web-design-with-macawrsquondash-free-book-updated.aspxThe free book on Macaw by Schonne Eldridge that I mentioned before has been updated. If you’re already subscribed you’ll get alerts for updates. If not the book is well worth getting to start you off with Macaw. If you haven’t tried Macaw yet, heck, you’re missing something big. The book is available from http://schonne.com/macaw Macaw itself is at http://macaw.co

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• New Book! SQL Server 2012 Integration Services Design Patterns!

  - by andyleonard

  SQL Server 2012 Integration Services Design Patterns has been released! The book is done and available thanks to the hard work and dedication of a great crew: Michelle Ufford ( Blog | @sqlfool ) – co-author Jessica M. Moss ( Blog | @jessicammoss ) – co-author Tim Mitchell ( Blog | @tim_mitchell ) – co-author Matt Masson ( Blog | @mattmasson ) – co-author Donald Farmer ( Blog | @donalddotfarmer ) – foreword David Stein ( Blog | @made2mentor ) – technical editing Mark Powers – editing Jonathan Gennick...(read more)

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