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  • Python, lambda, find minimum

    - by qba
    I have foreach function which calls specified function on every element which it contains. I want to get minimum from thise elements but I have no idea how to write lambda or function or even a class that would manage that. Thanks for every help. I use my foreach function like this: o.foreach( lambda i: i.call() ) or o.foreach( I.call ) I don't like to make a lists or other objects. I want to iterate trough it and find min. I manage to write a class that do the think but there should be some better solution than that: class Min: def __init__(self,i): self.i = i def get_min(self): return self.i def set_val(self,o): if o.val < self.i: self.i = o.val m = Min( xmin ) self.foreach( m.set_val ) xmin = m.get_min() Ok, so I suppose that my .foreach method is non-python idea. I should do my Class iterable because all your solutions are based on lists and then everything will become easier. In C# there would be no problem with lambda function like that, so I though that python is also that powerful.

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  • How do I implement IEnumerable?

    - by Stacey
    I have a class that contains a static number of objects. This class needs to be frequently 'compared' to other classes that will be simple List objects. public partial class Sheet { public Item X{ get; set; } public Item Y{ get; set; } public Item Z{ get; set; } } the items are obviously not going to be "X" "Y" "Z", those are just generic names for example. The problem is that due to the nature of what needs to be done, a List won't work; even though everything in here is going to be of type Item. It is like a checklist of very specific things that has to be tested against in both code and runtime. This works all fine and well; it isn't my issue. My issue is iterating it. For instance I want to do the following... List<Item> UncheckedItems = // Repository Logic Here. UncheckedItems contains all available items; and the CheckedItems is the Sheet class instance. CheckedItems will contain items that were moved from Unchecked to Checked; however due to the nature of the storage system, items moved to Checked CANNOT be REMOVED from Unchecked. I simply want to iterate through "Checked" and remove anything from the list in Unchecked that is already in "Checked". So naturally, that would go like this with a normal list. foreach(Item item in Unchecked) { if( Checked.Contains(item) ) Unchecked.Remove( item ); } But since "Sheet" is not a 'List', I cannot do that. So I wanted to implement IEnumerable so that I could. Any suggestions? I've never implemented IEnumerable directly before and I'm pretty confused as to where to begin.

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  • Creating a assertClass() method in JUnit

    - by Mike
    Hi, I'm creating a test platform for a protocol project based on Apache MINA. In MINA when you receive packets the messageReceived() method gets an Object. Ideally I'd like to use a JUnit method assertClass(), however it doesn't exist. I'm playing around trying to work out what is the closest I can get. I'm trying to find something similar to instanceof. Currently I have: public void assertClass(String msg, Class expected, Object given) { if(!expected.isInstance(given)) Assert.fail(msg); } To call this: assertClass("Packet type is correct", SomePacket.class, receivedPacket); This works without issue, however in experimenting and playing with this my interest was peaked by the instanceof operator. if (receivedPacket instanceof SomePacket) { .. } How is instanceof able to use SomePacket to reference the object at hand? It's not an instance of an object, its not a class, what is it?! Once establishing what type SomePacket is at that point is it possible to extend my assertClass() to not have to include the SomePacket.class argument, instead favouring SomePacket?

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  • manipulating radio box selection with javascript

    - by Crays
    Hi guys, i'm trying to do a poll but i designed it without any radio box in it. So i decided to make the selection being highlighted with a different background color, all is done with jquery. I set the display of the radio box to none so that it wouldn't show, gave each a unique ID. Here's the script. <form action="v_poll.php" method="post"> <ul class="voting"> <li class="voting votetext"><input type="radio" name="voting" value="a1" style="display:none;" id="a1"><a onClick="vote('a1')"Answer 1</a></li> <li class="voting votetext"><input type="radio" name="voting" value="a2" style="display:none;" id="a2"><a onClick="vote('a2')">Answer 2</a></li> <li class="voting votetext"><input type="radio" name="voting" value="a3" style="display:none;" id="a3"><a onClick="vote('a3')">Answer 3</a></li> <input type="hidden" value="1" name="id" /> <input type="submit" value="submit"> </ul> </form> <script type="text/javascript"> function vote(TheValue) { GetElementById(TheValue).checked=true; } </script> But when i checked the value of the radio box with $_POST['voting'], it is blank. Not the value assigned to the radio box. Anything i'm doing wrong? Please help. Thanks.

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  • Ruby on rails 2 level model

    - by jony17
    I need some help creating a very simple forum in a existing model. What I want in a Game page, have a mini forum, where is possible create some topics and some comments to this topics. In the beginning I'm only implement topics. This is the error I have: Mysql2::Error: Column 'user_id' cannot be null: INSERT INTO `topics` (`game_id`, `question`, `user_id`) VALUES (1, 'asd', NULL) This is my main model: game.rb class Game < ActiveRecord::Base attr_accessible :name validates :user_id, presence: true validates :name, presence: true, length: { maximum: 50 } belongs_to :user has_many :topics, dependent: :destroy end topic.rb class Topic < ActiveRecord::Base validates_presence_of :question validates_presence_of :game_id attr_accessible :question, :user_id validates :question, length: {maximum: 50}, allow_blank: false belongs_to :game belongs_to :user end topic_controller.rb def create @game = Game.find(params[:game_id]) @topic = @game.topics.create(params[:topic]) @topic.user_id = current_user.id respond_to do |format| if @topic.save format.html { redirect_to @game, notice: 'Topic was successfully created.' } else format.html { render action: "new" } end end end game/show.html.erb <h2>Topics</h2> <% @game.topics.each do |topic| %> <p> <b>Question:</b> <%= topic.question %> </p> <% end %> <h2>Add a topic:</h2> <%= form_for([@game, @game.topics.build]) do |f| %> <div class="field"> <%= f.label :question %><br /> <%= f.text_field :question %> </div> <div class="actions"> <%= f.submit %> </div> <% end %> Thanks ;)

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  • Unit Tests Architecture Question

    - by Tom Tresansky
    So I've started to layout unit tests for the following bit of code: public interface MyInterface { void MyInterfaceMethod1(); void MyInterfaceMethod2(); } public class MyImplementation1 implements MyInterface { void MyInterfaceMethod1() { // do something } void MyInterfaceMethod2() { // do something else } void SubRoutineP() { // other functionality specific to this implementation } } public class MyImplementation2 implements MyInterface { void MyInterfaceMethod1() { // do a 3rd thing } void MyInterfaceMethod2() { // do something completely different } void SubRoutineQ() { // other functionality specific to this implementation } } with several implementations and the expectation of more to come. My initial thought was to save myself time re-writing unit tests with something like this: public abstract class MyInterfaceTester { protected MyInterface m_object; @Setup public void setUp() { m_object = getTestedImplementation(); } public abstract MyInterface getTestedImplementation(); @Test public void testMyInterfaceMethod1() { // use m_object to run tests } @Test public void testMyInterfaceMethod2() { // use m_object to run tests } } which I could then subclass easily to test the implementation specific additional methods like so: public class MyImplementation1Tester extends MyInterfaceTester { public MyInterface getTestedImplementation() { return new MyImplementation1(); } @Test public void testSubRoutineP() { // use m_object to run tests } } and likewise for implmentation 2 onwards. So my question really is: is there any reason not to do this? JUnit seems to like it just fine, and it serves my needs, but I haven't really seen anything like it in any of the unit testing books and examples I've been reading. Is there some best practice I'm unwittingly violating? Am I setting myself up for heartache down the road? Is there simply a much better way out there I haven't considered? Thanks for any help.

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  • C# / this. and List<T>

    - by user3533030
    I am having trouble understanding how to initialize a List of objects and use it with methods inside of a class. I understand the mechanics of the List, but not how to initialize it inside a method and use it later. For example, I want to have a class that creates the List when it is constructed. Then, I want to use a method of that class to add elements to the list. The elements in the list are objects defined by the SolidWorks API. So, to construct the List, I used... public class ExportPoints : Exporter { public List<SldWorks.SketchPoint> listOfSketchPoints; public ExportPoints(SldWorks.SldWorks swApp, string nameSuffix) : base(swApp, nameSuffix) { List<SldWorks.SketchPoint> listOfSketchPoints = new List<SldWorks.SketchPoint>(); } public void createListOfFreePoints() { try { [imagine more code here] this.listOfSketchPoints.Add(pointTest); } catch (Exception e) { Debug.Print(e.ToString()); return; } } This fails during execution as if the listOfSketchPoints was never initialized as a List. So, I tried a hack and this worked: public ExportPoints(SldWorks.SldWorks swApp, string nameSuffix) : base(swApp, nameSuffix) { List<SldWorks.SketchPoint> listOfSketchPoints = new List<SldWorks.SketchPoint>(); this.listOfSketchPoints = listOfSketchPoints; } This approach creates the behavior that I want. However, it seems that I lack some understanding as to why this is necessary. Shouldn't it be possible to "initialize" a List that is a property of your object with a constructor? Why would you need to create the list, then assign the pointer of that new List to your property?

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  • Aggregation, Association and Composition (examples of code given)

    - by Bukocen
    I have such a simple example: public class Order { private ArrayList<Product> orders = new ArrayList<Product>(); public void add(Product p) { orders.add(p); } } Is it aggregation or composition? I guess it's composition, because orders will be delated after delete of Order, right? Unfortunately it was a task and answer was different;/ Do you know why? second problem: public class Client extends Person { String adress = ""; Orders orders = new Orders(); public Client(String n, String sn) { name = n; surName = sn; } public String getAddress() { return adress; } public Orders getOrders() { return this.orders; } } Is it Association between Client and Orders? My teacher told me that this is association, but I was wondering why it's not a aggregation/composition - he told me that aggregation or composition occur only when one class contains few instances of different class - is that right? I guess not, because e.g. car contains ONE wheel and it's aggregation I guess? What type of relation is that and why? Greetings

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  • Hide table row onclick using jquery

    - by John
    I have a bunch of table rows such as: <tr> <td>cell1</td> <td>cell2</td> <td><a href="action.php">cell3</a></td> </tr> <tr class="notes_row"> <td colspan="6"> <ul class="message warning no-margin" id="notes_box"> <li>Notes here</li> </ul> </td> </tr> <tr> <td>cell1</td> <td>cell2</td> <td><a href="action.php">cell3</a></td> </tr> The class="notes_row" is only there if notes are present for the row above it. How can I hide the tr and if its there the tr with the notes_row class below it without affecting the other rows using jquery? So if someone clicked cell3 the tr that link is in is hidden then if there is a notes table row below it, it hides that as well.

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  • Correct way to initialize dynamic Array in C++

    - by mef
    Hey guys, I'm currently working on a C++ project, where dynamic arrays often appear. I was wondering, what could be the correct way to initialize a dynamic array using the new-operator? A colleague of mine told me that it's a no-no to use new within the constructor, since a constructor is a construct that shouldn't be prone to errors or shouldn't fail at all, respectively. Now let's consider the following example: We have two classes, a more or less complex class State and a class StateContainer, which should be self-explained. class State { private: unsigned smth; public: State(); State( unsigned s ); }; class StateContainer { private: unsigned long nStates; State *states; public: StateContainer(); StateContainer( unsigned long n ); virtual ~StateContainer(); }; StateContainer::StateContainer() { nStates = SOME_DEFINE_N_STATES; states = new State[nStates]; if ( !states ) { // Error handling } } StateContainer::StateContainer( unsigned long n ) { nStates = n; try { states = new State[nStates] } catch ( std::bad_alloc &e ) { // Error handling } } StateContainer::~StateContainer() { if ( states ) { delete[] states; states = 0; } } Now actually, I have two questions: 1.) Is it ok, to call new within a constructor, or is it better to create an extra init()-Method for the State-Array and why? 2.) Whats the best way to check if new succeeded: if (!ptr) std::cerr << "new failed." or try { /*new*/ } catch (std::bad_alloc) { /*handling*/ } 3.) Ok its three questions ;o) Under the hood, new does some sort of ptr = (Struct *)malloc(N*sizeof(Struct)); And then call the constructor, right?

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  • How is covariance cooler than polymorphism...and not redundant?

    - by P.Brian.Mackey
    .NET 4 introduces covariance. I guess it is useful. After all, MS went through all the trouble of adding it to the C# language. But, why is Covariance more useful than good old polymorphism? I wrote this example to understand why I should implement Covariance, but I still don't get it. Please enlighten me. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Sample { class Demo { public delegate void ContraAction<in T>(T a); public interface IContainer<out T> { T GetItem(); void Do(ContraAction<T> action); } public class Container<T> : IContainer<T> { private T item; public Container(T item) { this.item = item; } public T GetItem() { return item; } public void Do(ContraAction<T> action) { action(item); } } public class Shape { public void Draw() { Console.WriteLine("Shape Drawn"); } } public class Circle:Shape { public void DrawCircle() { Console.WriteLine("Circle Drawn"); } } public static void Main() { Circle circle = new Circle(); IContainer<Shape> container = new Container<Circle>(circle); container.Do(s => s.Draw());//calls shape //Old school polymorphism...how is this not the same thing? Shape shape = new Circle(); shape.Draw(); } } }

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  • NoMethodError / undefined method `foobar_path' when using form_for

    - by user1850886
    I'm using form_for to create a chatroom and when I view the page I get the following error: NoMethodError in Chatrooms#new undefined method `chatrooms_path' for #<#<Class:0xa862b94>:0xa5307f0> Here's the code for the view, located in app/views/chatrooms/new.html.erb: <div class="center"> <%= form_for(@chatroom) do |f| %> <%=f.text_field :topic%> <br> <%=f.submit "Start a discussion", class: "btn btn-large btn-primary"%> <% end %> </div> Here's the relevant controller: class ChatroomsController < ApplicationController def new @chatroom = Chatroom.new end def show @chatroom = Chatroom.find(params[:id]) end end If I change the line <%= form_for(@chatroom) do |f| %> to <%= form_for(:chatroom) do |f| %> it works fine. I've searched around for similar questions but none of the solutions have worked for me. Help?

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  • Hibernate Relationship Mapping/Speed up batch inserts

    - by manyxcxi
    I have 5 MySQL InnoDB tables: Test,InputInvoice,InputLine,OutputInvoice,OutputLine and each is mapped and functioning in Hibernate. I have played with using StatelessSession/Session, and JDBC batch size. I have removed any generator classes to let MySQL handle the id generation- but it is still performing quite slow. Each of those tables is represented in a java class, and mapped in hibernate accordingly. Currently when it comes time to write the data out, I loop through the objects and do a session.save(Object) or session.insert(Object) if I'm using StatelessSession. I also do a flush and clear (when using Session) when my line count reaches the max jdbc batch size (50). Would it be faster if I had these in a 'parent' class that held the objects and did a session.save(master) instead of each one? If I had them in a master/container class, how would I map that in hibernate to reflect the relationship? The container class wouldn't actually be a table of it's own, but a relationship all based on two indexes run_id (int) and line (int). Another direction would be: How do I get Hibernate to do a multi-row insert?

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  • Using CSS to create three boxes with dividers and text centered within each box

    - by linnse
    I'm trying to figure out the best way to create a row of three boxes (columns), with dividers between boxes 1 and 2, and boxes 2 and 3. The text would need to be centered within each box. h2 { color: #00ADEF; margin-top:0; margin-bottom:0; font-family:Arial, Helvetica, sans-serif; font-size:20px; font-weight:bold; line-height:23px; } p { margin-top:0; } .3colwrapper { width: 930px; margin: 0 auto; } .colbox { float:left; margin: 10px; width: 210px; background:#DDD; padding:10px 40px; } <div class="3colwrapper"> <div class="colbox"><h2>Step One</h2> <p>Sign up</p> </div> <div class="colbox"><h2>Step Two</h2> <p>Verify</p> </div> <div class="colbox"><h2>Step Three</h2> <p>Participate</p> </div> </div> Here's what I've worked up so far: http://cssdesk.com/YyjAr

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  • How to determine number of function arguments dynamically

    - by Kam
    I have the following code: #include <iostream> #include <functional> class test { public: typedef std::function<bool(int)> Handler; void handler(Handler h){h(5);} }; class test2 { public: template< typename Ret2, typename Ret, typename Class, typename Param> inline Ret2 MemFn(Ret (Class::*f)(Param), int arg_num) { if (arg_num == 1) return std::bind(f, this, std::placeholders::_1); } bool f(int x){ std::cout << x << std::endl; return true;} }; int main() { test t; test2 t2; t.handler(t2.MemFn<test::Handler>(&test2::f, 1)); return 0; } It works as expected. I would like to be able to call this: t.handler(t2.MemFn<test::Handler>(&test2::f)); instead of t.handler(t2.MemFn<test::Handler>(&test2::f, 1)); Basically I need MemFn to determine in runtime what Handler expects as the number of arguments. Is that even possible?

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  • PHP: cannot matching string "<br />

    - by Patrick
    hi, I'm having problems with string matching in PHP. I've 2 html elements in my page, I've copy pasted here the content with Firebug <div class="field-item odd"> <div class="field-label-inline-first"> Year:</div> 2009 </div> <div class="field-item odd"> <div class="field-label-inline-first"> Synopsis:</div> &lt;br /&gt; </div> This php line works perfectly (the element with 2009 is detected) <?php if ($items[0]['view'] == '2009') : echo "ok"; ?> However I'm not able to match the string containing element: <?php if ($items[0]['view'] == '<br />') : echo "ok"; ?> //doesn't work <?php if ($items[0]['view'] == '&lt;br /&gt;') : echo "ok"; ?> //again doesn't work any tip ? To give you some context: The strings are produced by CKEditor, an editor I'm using in my Drupal back-end. When I leave empty this editor, the tag is displayed on the string as plain text (because I set "plain text" as formatting option in the back-end) Thanks

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  • VB.NET: WithEvents not Working

    - by Hei
    Hello All, I have the following classes: Public Class Email Private Shared ReadOnly EMAIL_REGEX = "\b[a-zA-Z]+[a-zA-Z0-9._+-]+@" + _ "[a-zA-Z0-9.-]+\.[a-zA-Z]{2,3}\b" Private _email As String Public Event emailCreated() ' Declare empty constructor private so the only way to create an object ' is using new (email) Private Sub New() End Sub Sub New(ByVal email As String) If Regex.IsMatch(email, EMAIL_REGEX) Then _email = email RaiseEvent emailCreated() Else Throw New Exception("Email Not Valid") End If End Sub ReadOnly Property Email() As String Get Return _email End Get End Property End Class And Public Class EmailForm WithEvents myEmail As Email Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Try myEmail = New Email(TextBox1.Text) Catch ex As Exception MessageBox.Show("Exception: " & ex.Message) End Try End Sub Public Sub emailCreated() Handles myEmail.emailCreated MessageBox.Show("New Email Created") End Sub End Class If a create a wrong email lets say "email" the exception is correctly cached and a message is showed however is i input a valid email the event is not raised, the object is being created but no message is shown and no error or exception is thrown i suspect it has something to do with using "myemail = new Email(email)" but i have seen examples of using new with withevents with no problem. I would apreciate any input about this problem thank you

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  • Location of DB models in Zend Framework - want them centralized

    - by jeffkolez
    Maybe I've been staring at the problem too long and it's much simpler than I think, but I'm stuck right now. I have three websites that are going to share database models. I've structured my applications so that I have an application directory for each site and a public directory for each site. The DB models live in a directory in the library along with Zend Framework and my third party libraries. I use the Autoloader class and when I try to instantiate one of my DB classes, it fails. The library directory is in my include path, but for whatever reason it refuses to instantiate my classes. It will work if I have my models in my application directory, but that's not the point. They're supposed to be shared classes in a Library. $model = new Model_Login(); $model->hello_world(); This fails when its in the library. The class is just a test: class Model_Login { public function hello_world() { echo "hello world"; } } Everything works until I try to instantiate one of my models. I've even tried renaming the class to something else (Db_Login), but that doesn't work either. Any ideas? Thanks in advance.

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  • Div Container Cleanup?

    - by Nto
    Just wondering if its possible to cleanup (less code needed to do the same thing) making this div container. Basically it's just a div with a background image however the top & bottom of the div have rounded graphical corners which is why I have a top, middle, and bottom div inside the container div. <div class="fbox"> <div class="ftop"></div> <div class="fmid"> Fullbox Text Goes Here </div> <div class="fbot"></div> </div> Css: .fbox { width: 934px; margin: 0 auto; opacity: 0.70; } .ftop { width: 934px; background:url(../images/cb/full.png) no-repeat 0 -34px; height: 17px; margin:0 } .fmid { width: 894px; padding-left: 20px; padding-right: 20px; background:url(../images/cb/fullmid.png) repeat-y; min-height: 50px; margin:0 } .fbot { width: 934px; background:url(../images/cb/full.png) no-repeat 0 -17px; height: 17px; margin:0 } Outcome: http://img709.imageshack.us/img709/6681/fbox.jpg

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  • Rails active record association problem

    - by Harm de Wit
    Hello, I'm new at active record association in rails so i don't know how to solve the following problem: I have a tables called 'meetings' and 'users'. I have correctly associated these two together by making a table 'participants' and set the following association statements: class Meeting < ActiveRecord::Base has_many :participants, :dependent => :destroy has_many :users, :through => :participants and class Participant < ActiveRecord::Base belongs_to :meeting belongs_to :user and the last model class User < ActiveRecord::Base has_many :participants, :dependent => :destroy At this point all is going well and i can access the user values of attending participants of a specific meeting by calling @meeting.users in the normal meetingshow.html.erb view. Now i want to make connections between these participants. Therefore i made a model called 'connections' and created the columns of 'meeting_id', 'user_id' and 'connected_user_id'. So these connections are kinda like friendships within a certain meeting. My question is: How can i set the model associations so i can easily control these connections? I would like to see a solution where i could use @meeting.users.each do |user| user.connections.each do |c| <do something> end end I tried this by changing the model of meetings to this: class Meeting < ActiveRecord::Base has_many :participants, :dependent => :destroy has_many :users, :through => :participants has_many :connections, :dependent => :destroy has_many :participating_user_connections, :through => :connections, :source => :user Please, does anyone have a solution/tip how to solve this the rails way?

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  • Hibernate many-to-many relationship

    - by Capitan
    I have two mapped types, related many-to-many. @Entity @Table(name = "students") public class Student{ ... @ManyToMany(fetch = FetchType.EAGER) @JoinTable( name = "students2courses", joinColumns = { @JoinColumn( name = "student_id", referencedColumnName = "_id") }, inverseJoinColumns = { @JoinColumn( name = "course_id", referencedColumnName = "_id") }) public Set<Course> getCourses() { return courses; } public void setCourses(Set<Course> courses) { this.courses = courses; } ... } __ @Entity @Table(name = "courses") public class Course{ ... @ManyToMany(fetch = FetchType.EAGER, mappedBy = "courses") public Set<Student> getStudents() { return students; } public void setStudents(Set<Student> students) { this.students = students; } ... } But if I update/delete Course entity, records are not created/deleted in table students2courses. (with Student entity updating/deleting goes as expected) I wrote abstract class HibObject public abstract class HibObject { public String getRemoveMTMQuery() { return null; } } which is inherited by Student and Course. In DAO I added this code (for delete() method): String query = obj.getRemoveMTMQuery(); if (query != null) { session.createSQLQuery(query).executeUpdate(); } and I ovrerided method getRemoveMTMQuery() for Course @Override @Transient public String getRemoveMTMQuery() { return "delete from students2courses where course_id = " + id + ";"; } Now it works but I think it's a bad code. Is there a best way to solve this problem?

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  • The cross-thread usage of "HttpContext.Current" property and related things

    - by smwikipedia
    I read from < Essential ASP.NET with Examples in C# the following statement: Another useful property to know about is the static Current property of the HttpContext class. This property always points to the current instance of the HttpContext class for the request being serviced. This can be convenient if you are writing helper classes that will be used from pages or other pipeline classes and may need to access the context for whatever reason. By using the static Current property to retrieve the context, you can avoid passing a reference to it to helper classes. For example, the class shown in Listing 4-1 uses the Current property of the context to access the QueryString and print something to the current response buffer. Note that for this static property to be correctly initialized, the caller must be executing on the original request thread, so if you have spawned additional threads to perform work during a request, you must take care to provide access to the context class yourself. I am wondering about the root cause of the bold part, and one thing leads to another, here is my thoughts: We know that a process can have multiple threads. Each of these threads have their own stacks, respectively. These threads also have access to a shared memory area, the heap. The stack then, as I understand it, is kind of where all the context for that thread is stored. For a thread to access something in the heap it must use a pointer, and the pointer is stored on its stack. So when we make some cross-thread calls, we must make sure that all the necessary context info is passed from the caller thread's stack to the callee thread's stack. But I am not quite sure if I made any mistake. Any comments will be deeply appreciated. Thanks. ADD Here the stack is limited to user stack.

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  • How to delete Drawn Line in java?

    - by Jeyjey
    Hello Folks, well this is my code: import javax.swing.; import javax.; import java.awt.; import java.awt.Color; import java.awt.Graphics.; import java.awt.event.*; import javax.swing.UIManager; public class SimpleGUI extends JFrame{ public SimpleGUI(){ this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ; } public void go(){ Drawpanel = new Mypanel(); JFrame frame = new JFrame("Chasing Line"); frame.getContentPane().add(BorderLayout.CENTER, Drawpanel); frame.setSize(300,300); frame.setVisible(true); Drawpanel.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() { public void mouseMoved(java.awt.event.MouseEvent evt) { DrawpanelMouseMoved(evt); } }); } public void DrawpanelMouseMoved(java.awt.event.MouseEvent evt) { xpos=evt.getX(); ypos=evt.getY(); System.out.println("Coordinates : X :"+ xpos+"Y: "+ypos); Drawpanel.paintImage(xpos,ypos); } class Mypanel extends JPanel{ public void paintImage(int xpost,int ypost){ Graphics d = getGraphics(); d.setColor(Color.black); d.drawLine(xpost, 0, xpost, this.getHeight()); d.setColor(Color.red); d.drawLine(0, ypost, this.getWidth(),ypost); this.validate(); } } // end the inner class public static void main(String[] args){ try { UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); } catch(Exception e) { System.err.println("Look and feel not set"); } SimpleGUI win = new SimpleGUI(); win.go(); } Mypanel Drawpanel; private int xpos=0; private int ypos=0; } // close SimpleGUI class The problem is how can i delete the old lines?, i mea,make only the current x and y lines appear on the screen, make the intersection between both lines "follow" the mouse pointer. thanks for any reply.

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  • How to insert rows in a many-to-many relationship

    - by GSound
    Hello, I am having an issue trying to save into an intermediate table. I am new on Rails and I have spent a couple of hours on this but can't make it work, maybe I am doing wrong the whole thing. Any help will be appreciated. =) The app is a simple book store, where a logged-in user picks books and then create an order. This error is displayed: NameError in OrderController#create uninitialized constant Order::Orderlist These are my models: class Book < ActiveRecord::Base has_many :orderlists has_many :orders, :through => :orderlists end class Order < ActiveRecord::Base belongs_to :user has_many :orderlists has_many :books, :through => :orderlists end class OrderList < ActiveRecord::Base belongs_to :book belongs_to :order end This is my Order controller: class OrderController < ApplicationController def add if session[:user] book = Book.find(:first, :conditions => ["id = #{params[:id]}"]) if book session[:list].push(book) end redirect_to :controller => "book" else redirect_to :controller => "user" end end def create if session[:user] @order = Order.new if @order.save session[:list].each do |b| @order.orderlists.create(:book => b) # <-- here is my prob I cant make it work end end end redirect_to :controller => "book" end end Thnx in advance! Manuel

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  • How do I code a tree of objects in Haskell with pointers to parent and children?

    - by axilmar
    I've got the following problem: I have a tree of objects of different classes where an action in the child class invalidates the parent. In imperative languages, it is trivial to do. For example, in Java: public class A { private List<B> m_children = new LinkedList<B>(); private boolean m_valid = true; public void invalidate() { m_valid = false; } public void addChild(B child) { m_children.add(child); child.m_parent = this; } } public class B { public A m_parent = null; private int m_data = 0; public void setData(int data) { m_data = 0; m_parent.invalidate(); } } public class Main { public static void main(String[] args) { A a = new A(); B b = new B(); b.setData(0); //invalidates A } } How do I do the above in Haskell? I cannot wrap my mind around this, since once I construct an object in Haskell, it cannot be changed. I would be much obliged if the relevant Haskell code is posted.

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