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  • Contingent Header Category Label

    - by poindexter
    Right now the header has a bit of code in it that queries the section name and then uses that section name as the h1 title in the page. It works fine. However, I want to selectively break that operation in certain categories and give myself the ability to manually enter the h1 title for a given section. Here's what I'm struggling with: how can I maintain the automatic query and title selection in most instances, but selectively break it in a given category (the 'blog' category, for starters)? Thanks for taking a look, I appreciate your help! Here's the code that drives the existing function (it's the get_the_section_name part): <?php if(!is_home()){?> <div class="section <?php echo get_the_section_name();?>"> <?php $sectitle = get_the_section_name(); $sectitle = str_ireplace("-"," ",$sectitle); echo '<h1>' . $sectitle . '</h1>';?> <p class="breadcrumbs"> <?php if(function_exists('bcn_display')) { bcn_display(); } ?> </p> </div> <div class="columns"> <?php } ?> Here's a page that shows what it looks like displayed (see the title in the blue graphic underneath the main nav near the top of the page): http://69.20.59.228/category/blog/

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  • How can I get an IObservable<T> in Rx from a "non-standard" event?

    - by Dan Tao
    Here's what I mean. Suppose I'm working with an API that exposes events, but these events do not follow the standard EventHandler or EventHandler<TEventArgs> signature. One event might look like this, for instance: Public Event Update(ByVal sender As BaseSubscription, ByVal e As BaseEvent) Now, typically, if I want to get an IObservable<TEventArgs> from an event, I can just do this: Dim updates = Observable.FromEvent(Of UpdateEventArgs)( _ target:=updateSource, _ eventName:="Update" _ ) But this doesn't work, because the Update event is not an EventHandler<UpdateEventArgs> -- in fact, there is no UpdateEventArgs -- it's basically just its own thing. Obviously, I could define my own class deriving from EventArgs (i.e., UpdateEventArgs), write another class to wrap the object providing the Update event, give the wrapper class its own Update event that is an EventHandler<UpdateEventArgs>, and get an IObservable<UpdateEventArgs> from that. But that's an annoying amount of work. Is there some way to create an IObservable<[something]> from a "non-standard" event like this, or am I out of luck?

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  • Constraint Validation

    - by tanuja
    I am using javax.validation.Validator and relevant classes for annotation based validation. Configuration<?> configuration = Validation.byDefaultProvider().configure(); ValidatorFactory factory = configuration.buildValidatorFactory(); Validator validator = factory.getValidator(); Set<ConstraintViolation<ValidatableObject>> constraintViolations = validator.validate(o); for (ConstraintViolation<ValidatableObject> value : constraintViolations) { List< Class< ? extends ConstraintValidator< ? extends Annotation,?>>> list = value.getConstraintDescriptor().getConstraintValidatorClasses(); } I get a compilation error stating: Type mismatch: cannot convert from List< Class< ? extends ConstraintValidator< capture#4-of ?,? to List< Class< ? extends ConstraintValidator< ? extends Annotation,? What am I missing?

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  • Conditional column values in NSTableView?

    - by velocityb0y
    I have an NSTableView that binds via an NSArrayController to an NSMutableArray. What's in the array are derived classes; the first few columns of the table are bound to properties that exist on the base class. That all works fine. Where I'm running into problem is a column that should only be populated if the row maps to one specific subclass. The property that column is meant to display only exists in that subclass, since it makes no sense in terms of the base class. The user will know, from the first two columns, why the third column's cell is populated/editable or not. The binding on the third column's value is on arrangedObjects, with a model path of something like "foo.name" where foo is the property on the subclass. However, this doesn't work, as the other subclasses in the hierarchy are not key-value compliant for foo. It seems like my only choice is to have foo be a property on the base class so everybody responds to it, but this clutters up the interfaces of the model objects. Has anyone come up with a clean design for this situation? It can't be uncommon (I'm a relative newcomer to Cocoa and I'm just learning the ins and outs of bindings.)

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  • Is this WPF error handling a good idea ?

    - by Adiel
    I have a multi threaded wpf application with various HW interfaces. I want to react to several HW failures that can happen. For example : one of the interfaces is a temperature sensor and i want that from a certain temp. a meesage would appear and notify the user that it happened. i came up with the follwing design : /// <summary> /// This logic reacts to errors that occur during the system run. /// The reaction is set by the component that raised the error. /// </summary> public class ErrorHandlingLogic : Logic { } the above class would consume ErrorEventData that holds all the information about the error that occurred. public class ErrorEventData : IEventData { #region public enum public enum ErrorReaction { } #endregion public enum #region Private Data Memebers and props private ErrorReaction m_ErrorReaction; public ErrorReaction ErrorReactionValue { get { return m_ErrorReaction; } set { m_ErrorReaction = value; } } private string m_Msg; public string Msg { get { return m_Msg; } set { m_Msg = value; } } private string m_ComponentName; public string ComponentName { get { return m_ComponentName; } set { m_ComponentName = value; } } #endregion Private Data Memebers and props public ErrorEventData(ErrorReaction reaction, string msg, string componenetName) { m_ErrorReaction = reaction; m_Msg = msg; m_ComponentName = componenetName; } } the above ErrorHandlingLogic would decide what to do with the ErrorEventData sent to him from various components of the application. if needed it would be forwarded to the GUI to display a message to the user. so what do you think is it a good design ? thanks, Adiel.

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  • Passing params in rails... Breakthrough in understanding params, aka, the "aha" moment

    - by Brian McDonough
    I have a simple has_many belongs_to relationship and I want to include the parent object for the view of the belongs_to model and I have had some success, but I want it to work better. class Submission < ActiveRecord::Base belongs_to :user belongs_to :contest end class Contest < ActiveRecord::Base belongs_to :user has_many :submissions, :dependent => :destroy end In the case that works, I pass contest_id to submissions by placing it in the url: <%= link_to 'Submit Contest Entry', new_submission_path(:contest_id => @contest.id), :class => 'btn btn-primary btn-large mleft10' %> So that, combined with a hidden_field: <%= f.hidden_field :contest_id %> And a find_contest method in the controller (called with a before_filter): def find_contest #the next line is giving the error (line 76) @contest = Contest.find(params[:submission][:contest_id]) end Makes it work for submissions/new, but how do I add a find to the controller that just works across more than that one page, like if I want to access in show and index. Right now, I get an error: Started GET "/submissions?contest_id=5" for 127.0.0.1 at 2012-12-01 16:01:45 -0800 Processing by SubmissionsController#index as HTML Parameters: {"contest_id"=>"5"} User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = 2 ORDER BY users.created_at DESC LIMIT 1 Completed 500 Internal Server Error in 37ms NoMethodError (undefined method `[]' for nil:NilClass): app/controllers/submissions_controller.rb:76:in `find_contest' [edited] Adding show action for submissions: before_filter :find_contest, :except => [:index, :show, :edit, :update, :destroy] def find_contest @contest = Contest.find(params[:submission][:contest_id]) end def show contest_id = @submission.contest_id @submission = @commentable = Submission.find(params[:id]) @comments = @commentable.comments.order(:created_at).reverse respond_to do |format| format.html # show.html.erb format.json { render :json => @submission } end end

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  • How to Return Variable for all tests to use Unittest

    - by chrissygormley
    Hello, I have a Python script and I am trying to set a variable so that if the first test fail's the rest of then will be set to fail. The script I have so far is: class Tests(): def function: result function.......... def errorHandle(self): return self.error def sudsPass(self): try: result = self.client.service.GetStreamUri(self.stream, self.token) except suds.WebFault, e: assert False except Exception, e: pass finally: if 'result' in locals(): self.error = True self.errorHandle() assert True else: self.error = False self.errorHandle() assert False def sudsFail(self): try: result = self.client.service.GetStreamUri(self.stream, self.token) except suds.WebFault, e: assert False except Exception, e: pass finally: if 'result' in locals() or self.error == False: assert False else: assert True class GetStreamUri(TestGetStreamUri): def runTest(self): self.sudsPass() class GetStreamUriProtocolFail(TestGetStreamUri): def runTest(self): self.stream.Transport.Protocol = "NoValue" self.errorHandle() self.sudsFail() if __name__ == '__main__': unittest.main() I am trying to get self.error to be set to False if the first test fail. I understand that it is being set in another test but I was hoping someone could help me find a solution to this problem using some other means. Thanks PS. Please ignore the strange tests. There is a problem with the error handling at the moment.

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  • SPRING: How do you programmatically instantiate classes based on information passed from Flex UI

    - by babyangel86
    Imagine the UI passes back an XMl node as such: <properties> <type> Source </type> <name> Blooper </name> <delay> <type> Deterministic </type> <parameters> <param> 4 </param> </parameters> <delay> <batch> <type> Erlang </type> <parameters> <param> 4 </param> <param> 6 </param> </parameters> <batch> And behind the scene what it is asking that you instantiate a class as such: new Source("blooper", new Exp(4), new Erlang(4,6); The problem lies in the fact that you don't know what class you will need to processing, and you will be sent a list of these class definitions with instructions on how they can be linked to each other. I've heard that using a BeanFactoryPostProcessor might be helpful, or a property editor/convertor. However I am at a loss as to how best to use them to solve my problem. Any help you can provide will be much appreciated.

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  • Need a workaround to filter on related model and aggregated fields in Django

    - by parxier
    I opened a ticket for this problem. In a nutshell here is my model: class Plan(models.Model): cap = models.IntegerField() class Phone(models.Model): plan = models.ForeignKey(Plan, related_name='phones') class Call(models.Model): phone = models.ForeignKey(Phone, related_name='calls') cost = models.IntegerField() I want to run a query like this one: Phone.objects.annotate(total_cost=Sum('calls__cost')).filter(total_cost__gte=0.5*F('plan__cap')) Unfortunately Django generates bad SQL: SELECT "app_phone"."id", "app_phone"."plan_id", SUM("app_call"."cost") AS "total_cost" FROM "app_phone" INNER JOIN "app_plan" ON ("app_phone"."plan_id" = "app_plan"."id") LEFT OUTER JOIN "app_call" ON ("app_phone"."id" = "app_call"."phone_id") GROUP BY "app_phone"."id", "app_phone"."plan_id" HAVING SUM("app_call"."cost") >= 0.5 * "app_plan"."cap" and errors with: ProgrammingError: column "app_plan.cap" must appear in the GROUP BY clause or be used in an aggregate function LINE 1: ...."plan_id" HAVING SUM("app_call"."cost") >= 0.5 * "app_plan".... Is there any workaround apart from running raw SQL?

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  • Drawing graphics on top of a JButton

    - by trinth
    I have a situation wherein I have a bunch of JButtons on a GridLayout. I need each of the JButtons to have: a background image (but retain the ability to keep the default button look if needed) custom graphics drawn on top by other classes I have no trouble with the background image, since I am using setIcon() but I am having problems drawing things on top of the background. At one point I was able to draw on top of the button, but after the button was clicked, the drawings disappeared. How can make the button keep this drawing state? Basically, I need a way for my JButtons to have public methods that would allow another class to draw anything on it such as: public void drawSomething() { Graphics g = this.getGraphics(); g.drawOval(3,2,2,2); repaint(); } or public Graphics getGraphics() { return this.getGraphics(); } then another class could do this: button.getGraphics().drawSomething(); The latter is more what I am looking for but the first is equally useful. Is there any way to go about this? Also, overriding the parent class method paintComponent() doesn't help since I need each button to have different graphics.

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  • Loading default value in a dropdown and calling onchange event

    - by J. Davidson
    Hi i have following dropdown <div class="fcolumn"> <label class="text" for="o_Id">Months:</label> <select class="textMonths" id="o_Id" name="periodName" > <option value="000">Select Period--</option> </select> </div> In the following jquery, first it loads fnLoadP() in a drop down list. Than as a default I am loading one of the values in drop down which is '10'. It loads too as default value. But it should be executing $("#o_Id").change.. which it doesn't. $(document).ready(function () { var sProfileUserId = null; $("#o_Id").change(function () { //---- }); fnLoadP(); $("select[name='pName']").val('10'); }); }); Basically my goal is. After dropdown values are loaded, to load '10' as default value and call onchange event in the dom. Please let me know how to fix it.

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  • DataGridView not displaying data in ToolStripControlHost

    - by jblaske
    I'm utilizing the code posted by Jesper Palm here: http://stackoverflow.com/questions/280891/make-user-control-display-outside-of-form-boundry /// <summary> /// A simple popup window that can host any System.Windows.Forms.Control /// </summary> public class PopupWindow : System.Windows.Forms.ToolStripDropDown { private System.Windows.Forms.Control _content; private System.Windows.Forms.ToolStripControlHost _host; public PopupWindow(System.Windows.Forms.Control content) { //Basic setup... this.AutoSize = false; this.DoubleBuffered = true; this.ResizeRedraw = true; this._content = content; this._host = new System.Windows.Forms.ToolStripControlHost(content); //Positioning and Sizing this.MinimumSize = content.MinimumSize; this.MaximumSize = content.Size; this.Size = content.Size; content.Location = Point.Empty; //Add the host to the list this.Items.Add(this._host); } } I've translated it to VB: Public Class PopupWindow Inherits System.Windows.Forms.ToolStripDropDown Private _content As System.Windows.Forms.Control Private _host As System.Windows.Forms.ToolStripControlHost Public Sub New(ByVal content As System.Windows.Forms.Control) Me.AutoSize = False Me.DoubleBuffered = True Me.ResizeRedraw = True Me._content = content Me._host = New System.Windows.Forms.ToolStripControlHost(content) Me.MinimumSize = content.MinimumSize Me.MaximumSize = content.MaximumSize Me.Size = content.Size content.Location = Point.Empty Me.Items.Add(Me._host) End Sub End Class It works great with a PictureBox showing its information. But for some reason I cannot get the DataGridView to display anything when it is in the popup. If I pull the grid out of the popup it displays all of its information fine. If I pause during debug, the grid shows that it has all the data in it. It's just not displaying anything. Does anybody have any ideas?

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  • ReaderWriterLockSlim and Pulse/Wait

    - by Jono
    Is there an equivalent of Monitor.Pulse and Monitor.Wait that I can use in conjunction with a ReaderWriterLockSlim? I have a class where I've encapsulated multi-threaded access to an underlying queue. To enqueue something, I acquire a lock that protects the underlying queue (and a couple of other objects) then add the item and Monitor.Pulse the locked object to signal that something was added to the queue. public void Enqueue(ITask task) { lock (mutex) { underlying.Enqueue(task); Monitor.Pulse(mutex); } } On the other end of the queue, I have a single background thread that continuously processes messages as they arrive on the queue. It uses Monitor.Wait when there are no items in the queue, to avoid unnecessary polling. (I consider this to be good design, but any flames (within reason) are welcome if they help me learn otherwise.) private void DequeueForProcessing(object state) { while (true) { ITask task; lock (mutex) { while (underlying.Count == 0) { Monitor.Wait(mutex); } task = underlying.Dequeue(); } Process(task); } } As more operations are added to this class (requiring read-only access to the lock protected underlying), someone suggested using ReaderWriterLockSlim. I've never used the class before, and assuming it can offer some performance benefit, I'm not against it, but only if I can keep the Pulse/Wait design.

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  • C++ brain teaser

    - by mxp
    I recently refactored code like this (MyClass to MyClassR). class SomeMember { long m_value; public: SomeMember() : m_value(0) {} SomeMember(int a) : m_value(a) {} SomeMember(int a, int b) : m_value(a+b) {} }; class MyClass { SomeMember m_first, m_second, m_third; public: MyClass(const bool isUp, const int x, const int y) { if (isUp) { m_first = SomeMember(x); m_second = SomeMember(y); m_third = SomeMember(x, y); } else { m_first = SomeMember(y); m_second = SomeMember(x); m_third = SomeMember(y, x); } } }; class MyClassR { SomeMember m_first, m_second, m_third; public: MyClassR(const bool isUp, const int x, const int y) : m_first(isUp ? x : y) , m_second(isUp ? y : x) , m_third(isUp ? x, y : y, x) { } }; What is the error, why does it compile (at least VC6 with warning level 3 doesn't complain) and what is the right way of doing it? I (assume) I already have all these answers but I think it's and interesting problem to share.

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  • cant calculate width of elements

    - by Kein
    I try to get width of dom objects: function resizeArea(){ var width = 0; area.children().each(function(i){ alert(this.offsetWidth); width += this.offsetWidth; }); area.css('width', width); } In get results: Chrome: 800 Opera: 708 FF: 783 IE: 714 But if see it in firebug, dragonfly and other debuggers i see correct 908px. I don't know where porblem. I run this fun after domloaded. Here is HTML and css of block: <div class="scroll_area" id="scroll"> <div class="area" id="area"> <div class="category"> [..] </div> </div> </div> <style> #scroll { position:realtive; width: 800px, heght: 400px; } #area { position:absolute; left: 0; top: 0; } #area .category, #area .category .text, #area .category .image{ width: 200px } </style> And that interesting. This function later work correctly, only at first run, for first calculating.

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  • problems with retrieving data that was saved outside of a grails webflow

    - by callie16
    Hi, this is actually connected to an earlier question of mine here. Anyway, I have 3 domains that look like this: class A { ... static hasMany = [ b : B ] ... } class B { ... static belongsTo = [ a : A ] static hasMany = [ c : C ] ... } class C { ... static belongsTo = [ b : B ] ... } In my GSP page, I call an action in the Controller via a remote function in a javascript block (I'm using Dojo so I'm passing data to be saved this way... it's not a form per se so I use JSON for now to pass the data to the Controller). Let's say, I'm calling something like this: def someAction = { def jsonArr = [parse the JSON here] def tmpA = A.get(params.id) ... def tmpB = new B() b.someParam = jsonArr.someParam ... def tmpC = new C() tmpC.cParam = jsonArr.cParam tmpB.addToC(tmpC) tmpB.save(flush: true) //this may or may not be here but I'm adding it for the sake of completeness tmpA.addToB(tmpB) tmpA.save(flush: true) // NOTE: If I check here via println or whatnot, tmpA has a tmpB which has a tmpC... in other words, the data got saved. It's also in the DB. redirect(action: 'order' ...) } Then comes the fun part. Here's the webflow sample: def orderFlow = { ... someStateIShouldEndUpIn { on("next") { // or on previous... doesn't matter def anId = params.id def currA = A.get(anId) // this does NOT return a null value def testB = currA.b // this DOES return a null value }.to("somePage") ... } ... } Any ideas on why this happens? Moreover, when I dump the data of currA, b=null... instead of b=[] or b=[contents of tmpB]. Any help would be seriously appreciated... been at this for a couple of days now... Thanks!

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  • CakePHP: Interaction between different files/classes

    - by Alexx Hardt
    Hey, I'm cloning a commercial student management system. Students use the frontend to apply for lectures, uni staff can modify events (time, room, etc). The core of the app will be the algortihm which distributes the seats to students. I already asked about it here: How to implement a seat distribution algorithm for uni lectures Now, I found a class for that algorithm here: http://www.phpclasses.org/browse/file/10779.html I put the 'class GA' into app/vendors. I need to write a 'class Solution', which represents one object (a child, and later a parent for the evolutionary process). I'll also have to write functions mutate(), crossover() and fitness(). fitness calculates a score of a solution, based on if there are overbooked courses etc; crossover() is the crazy monkey sex function which produces a child from two parents, and mutate() modifies a child after crossover. Now, the fitness()-function needs to access a few related models, and their find()-functions. It evaluates a solution's fitness by checking e.g. if there are overbooked courses, or unfulfilled wishes, and penalizes that. Where would I put the ga.php, solution.php and the three functions? ga.php has to access the functions, but the functions have to access the models. I also don't want to call any App::import()'s from within the fitness()-function, because it gets called many thousand times when the algorithm runs. Hope someone can help me. Thanks in advance =)

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  • Howto serialize multiple Lists with Jquery

    - by megens
    I have 3 sortable UL's and a simple jquery/javascript <ul class="sortable" id="menu1"> <li id="id_1">whatever</li> <li id="id_2">you</li> </ul> <ul class="sortable" id="menu2"> <li id="id_3">wanne</li> <li id="id_4">put</li> </ul> <ul class="sortable" id="menu3"> <li id="id_5">in</li> <li id="id_6">here</li> </ul> $(function() { $("ul.sortable").sortable({ connectWith: 'ul' }); }); </script> LI's are draggable between UL's How can i serialize this so i get for example menu1[0]=1&menu1[1]=3 Or and array or whatever i can work with to save the state?

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  • HTML href with css ie Problem

    - by Jordan Pagaduan
    <style type="text/css"> .web_westloh { background-image: url(images/web_westloh.png); background-repeat: no-repeat; height: 100px; width: 350px; } .web_westloh:hover { border-bottom-width: 2px; border-bottom-style: dashed; border-bottom-color: #999999; padding-bottom: 5px; } .web_money { background-image: url(images/web_money.png); background-repeat: no-repeat; height: 100px; width: 350px; } .web_money:hover { border-bottom-width: 2px; border-bottom-style: dashed; border-bottom-color: #999999; padding-bottom: 5px; } </style> <a href="http://www.westloh.com" title="Click to Visit http://www.westloh.com" target="_blank" class="web_westloh"> <div class="web_westloh"></div> </a> <a href="http://www.money-mind-set.com" title="Click to Visit http://www.money-mind-set.com" target="_blank"> <div class="web_money"></div> </a> The Problem is: In mozilla linking is ok. No problem. But in IE the link is a problem, it will not link in the target. See this page to see Problem: http://replytowest.com -- at the bottom. Thank You

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  • Enum "copy" problem

    - by f0b0s
    Hi all! I have a class, let's call it A. It has a enum (E) and a method Foo(E e), with gets E in the arguments. I want to write a wrapper (decorator) W for A. So it'll have its own method Foo(A::E). But I want to have some kind of encapsulation, so this method should defined as Foo(F f), where F is another enum defined in W, that can be converted to A::E. For example: class A { public: enum E { ONE, TWO, THREE }; void Foo(E e); }; class B { //enum F; // ??? void Foo(F f) { a_.Foo(f); } private: A a_; }; How F should be defined? I don't want to copy value like this: enum F { ONE = A::ONE, TWO = A::TWO, THREE = A::THREE }; because its a potential error in the near feature. Is the typedef definition: typedef A::E F; is the best decision? Is it legal?

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  • Java: autofiltering list?

    - by Jason S
    I have a series of items arriving which are used in one of my data structures, and I need a way to keep track of those items that are retained. interface Item {} class Foo implements Item { ... } class Baz implements Item { ... } class StateManager { List<Foo> fooList; Map<Integer, Baz> bazMap; public List<Item> getItems(); } What I want is that if I do the following: for (int i = 0; i < SOME_LARGE_NUMBER; ++i) { /* randomly do one of the following: * 1) put a new Foo somewhere in the fooList * 2) delete one or more members from the fooList * 3) put a new Baz somewhere in the bazMap * 4) delete one or more members from the bazMap */ } then if I make a call to StateManager.getItems(), I want to return a list of those Foo and Baz items, which are found in the fooList and the bazMap, in the order they were added. Items that were deleted or displaced from fooList and bazMap should not be in the returned list. How could I implement this? SOME_LARGE_NUMBER is large enough that I don't have the memory available to retain all the Foo and Baz items, and then filter them.

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  • Help me write my LISP :) LISP environments, Ruby Hashes...

    - by MikeC8
    I'm implementing a rudimentary version of LISP in Ruby just in order to familiarize myself with some concepts. I'm basing my implementation off of Peter Norvig's Lispy (http://norvig.com/lispy.html). There's something I'm missing here though, and I'd appreciate some help... He subclasses Python's dict as follows: class Env(dict): "An environment: a dict of {'var':val} pairs, with an outer Env." def __init__(self, parms=(), args=(), outer=None): self.update(zip(parms,args)) self.outer = outer def find(self, var): "Find the innermost Env where var appears." return self if var in self else self.outer.find(var) He then goes on to explain why he does this rather than just using a dict. However, for some reason, his explanation keeps passing in through my eyes and out through the back of my head. Why not use a dict, and then inside the eval function, when a new "sub-environment" needs to be created, just take the existing dict and update the key/value pairs that need to be updated, and pass that new dict into the next eval? Won't the Python interpreter keep track of the previous "outer" envs? And won't the nature of the recursion ensure that the values are pulled out from "inner" to "outer"? I'm using Ruby, and I tried to implement things this way. Something's not working though, and it might be because of this, or perhaps not. Here's my eval function, env being a regular Hash: def eval(x, env = $global_env) ........ elsif x[0] == "lambda" then ->(*args) { eval(x[2], env.merge(Hash[*x[1].zip(args).flatten(1)])) } ........ end The line that matters of course is the "lambda" one. If there is a difference, what's importantly different between what I'm doing here and what Norvig did with his Env class? If there's no difference, then perhaps someone can enlighten me as to why Norvig uses the Env class. Thanks :)

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  • What is wrong with locking non-static fields? What is the correct way to lock a particular instance?

    - by smartcaveman
    Why is it considered bad practice to lock non-static fields? And, if I am not locking non-static fields, then how do I lock an instance method without locking the method on all other instances of the same or derived class? I wrote an example to make my question more clear. public abstract class BaseClass { private readonly object NonStaticLockObject = new object(); private static readonly object StaticLockObject = new object(); protected void DoThreadSafeAction<T>(Action<T> action) where T: BaseClass { var derived = this as T; if(derived == null) { throw new Exception(); } lock(NonStaticLockObject) { action(derived); } } } public class DerivedClass :BaseClass { private readonly Queue<object> _queue; public void Enqueue(object obj) { DoThreadSafeAction<DerivedClass>(x=>x._queue.Enqueue(obj)); } } If I make the lock on the StaticLockObject, then the DoThreadSafeAction method will be locked for all instances of all classes that derive from BaseClass and that is not what I want. I want to make sure that no other threads can call a method on a particular instance of an object while it is locked.

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  • Vertically Aligning Divs

    - by Crays
    Hi, i'm trying to make a small username and password input box. I would like to ask how do you vertically align a div? What i have is a <div id="Login" class="BlackStrip floatright"> <div id="Username" class="floatleft">Username<br>Password</div> <div id="Form" class="floatleft"> <form action="" method="post"> <input type="text" border="0"><br> <input type="password" border="0"> </form> </div> </div> and how can i make the div with id Username and Form to vertically align itself to the center? I tried putting vertical-align: middle; in css for the div with id Login. But doesn't seem to work. Any help would be appreciated. Thanks.

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  • wpf observableCollection

    - by Asha
    I have an ObservableCollection which is dataContext for my treeview when I try to remove an Item from ObservableCollection I will get an error that Object reference not set to an instance of an object . can you please tell me why this error is happening and what is the solution thanks EDIT 1: The code is something like : class MyClass : INotifyPropertyChanged { //my class code here } public partial class UC_myUserControl : UserControl { private ObservableCollection<MyClass> myCollection = new ObservableCollection<MyClass>(); private void UserControl_Loaded(object sender, RoutedEventArgs e) { myCollection.add(new myClass); myTreeView.DataContext = myCollection ; } private void deleteItem() { myCollection.RemoveAt(0); //after removing I get error Which I guess should be something related //to interface update but I don't know how can I solve it } } Exception Detail : System.NullReferenceException was unhandled Message="Object reference not set to an instance of an object." Source="PresentationFramework" EDIT 3: I have a style which is for my treeitem to keep the treeitems expanded <Style TargetType="TreeViewItem"> <Setter Property="IsExpanded" Value="True" /> </Style> and with commenting this part I wont get any error !!! Now I want to change my question to why having this style is causing error ?

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