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  • Elements of a Java Object Array are created but without correct names

    - by Greenhouse Gases
    Hi all Im having rather an annoying problem. I have a class called Person and a class called Event which serve to create objects to be used for competitors that compete in a certain event. When I add a competitor thats fine and the GUI list updates accordingly, however when I add an event the element in the array does not take on the value of the instance variable name in the class Event and so the GUI does not show the event name, though it is being added in the array correctly. How can I make it so that the event object in each element of the listOfEvents array (which is an array of event objects) has the name of the event. I should add this is for university though this isnt the part for which we will be assessed, it is somethign i have come across and due to not being able to see the code for the GUI, I've hit the proverbial brick wall. I wont include the whole load of code Ive been writing but hopefully my description and snippets below will suffice. Any advice I would appreciate greatly. No doubt I have overlooked something simple! Many thanks. listOfEvents is declared as: Event[] listOfEvents = new Event[20]; A snippet from the Event class: public class Event { String name; Person[] participants = new Person[10]; // array of competitors for the event public Event(String name) { this.name = name; } } and its use in the addEvent method (p is a global variable): public void addEvent(String eventName) { listOfEvents[p] = new Event(eventName); p++; }

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  • Parsing a Multi-Index Excel File in Pandas

    - by rhaskett
    I have a time series excel file with a tri-level column MultiIndex that I would like to successfully parse if possible. There are some results on how to do this for an index on stack overflow but not the columns and the parse function has a header that does not seem to take a list of rows. The ExcelFile looks like is like the following: Column A is all the time series dates starting on A4 Column B has top_level1 (B1) mid_level1 (B2) low_level1 (B3) data (B4-B100+) Column C has null (C1) null (C2) low_level2 (C3) data (C4-C100+) Column D has null (D1) mid_level2 (D2) low_level1 (D3) data (D4-D100+) Column E has null (E1) null (E2) low_level2 (E3) data (E4-E100+) ... So there are two low_level values many mid_level values and a few top_level values but the trick is the top and mid level values are null and are assumed to be the values to the left. So, for instance all the columns above would have top_level1 as the top multi-index value. My best idea so far is to use transpose, but the it fills Unnamed: # everywhere and doesn't seem to work. In Pandas 0.13 read_csv seems to have a header parameter that can take a list, but this doesn't seem to work with parse.

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  • Method returns an IDisposable - Should I dispose of the result, even if it's not assigned to anythin

    - by mjd79
    This seems like a fairly straightforward question, but I couldn't find this particular use-case after some searching around. Suppose I have a simple method that, say, determines if a file is opened by some process. I can do this (not 100% correctly, but fairly well) with this: public bool IsOpen(string fileName) { try { File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.None); } catch { // if an exception is thrown, the file must be opened by some other process return true; } } (obviously this isn't the best or even correct way to determine this - File.Open throws a number of different exceptions, all with different meanings, but it works for this example) Now the File.Open call returns a FileStream, and FileStream implements IDisposable. Normally we'd want to wrap the usage of any FileStream instantiations in a using block to make sure they're disposed of properly. But what happens in the case where we don't actually assign the return value to anything? Is it still necessary to dispose of the FileStream, like so: try { using (File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.None)); { /* nop */ } } catch { return true; } Should I create a FileStream instance and dispose of that? try { using (FileStream fs = File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.None)); } ... Or are these totally unnecessary? Can we simply call File.Open and not assign it to anything (first code example), and let the GC dispose of it right away?

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  • Risky Business with LINQ to SQL and OR Designer?

    - by Toadmyster
    I have two tables with a one to many relationship in SQL 2008. The first table (BBD) PK | BBDataID | int       | Floor_Qty | tinyint       | Construct_Year | char(4)       | etc, etc describes the data common to all buildings and the second (BBDCerts) PK | BBDCertsID | int       | BBDataID | int       | Certification_Type | varchar(20)       | etc, etc is a collection of certifications for a particular building. Thus, the primary key in BBD (BBDataID) is mapped to the corresponding field in BBDCerts via an FK relationship, but BBDCertsID is the second table's primary key and BBDataID is not because it will not be unique. My problem is that I want to be able to use the OR generated data context to get at the list of certs when I access a particular record in the BBD table. For instance: Dim vals = (From q in db.BBD Where q.BBDataID = x Select q.Floor_Qty, q.Construct_Year, q.BBDCerts).SingleOrDefault and later be able to access a particular certification like this: vals.BBDCerts.Certification_Type.First Now, the automatic associations created when the SQL tables are dropped on the design surface don't generate the EntityRef associations that are needed to access the other table using the dot notation. So, I have to use the OR designer to make the BBDCerts BBDataID a primary key (this doesn't affect the actual database), and then manually change the association properties to the appropriate OneToMany settings. There might be a better way to approach this solution but my question is, is the way I've done it safe? I've done a barrage of tests and the correct cert is referenced or updated every time. Frankly, the whole thing makes me nervous.

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  • multiple models in Rails with a shared interface

    - by dfondente
    I'm not sure of the best structure for a particular situation in Rails. We have several types of workshops. The administration of the workshops is the same regardless of workshop type, so the data for the workshops is in a single model. We collect feedback from participants about the workshops, and the questionnaire is different for each type of workshop. I want to access the feedback about the workshop from the workshop model, but the class of the associated model will depend on the type of workshop. If I was doing this in something other than Rails, I would set up an abstract class for WorkshopFeedback, and then have subclasses for each type of workshop: WorkshopFeedbackOne, WorkshopFeedbackTwo, WorkshopFeedbackThree. I'm unsure how to best handle this with Rails. I currently have: class Workshop < ActiveRecord::Base has_many :workshop_feedbacks end class Feedback < ActiveRecord::Base belongs_to :workshop has_many :feedback_ones has_many :feedback_twos has_many :feedback_threes end class FeedbackOne < ActiveRecord::Base belongs_to :feedback end class FeedbackTwo < ActiveRecord::Base belongs_to :feedback end class FeedbackThree < ActiveRecord::Base belongs_to :feedback end This doesn't seem like to the cleanest way to access the feedback from the workshop model, as accessing the correct feedback will require logic investigating the Workshop type and then choosing, for instance, @workshop.feedback.feedback_one. Is there a better way to handle this situation? Would it be better to use a polymorphic association for feedback? Or maybe using a Module or Mixin for the shared Feedback interface? Note: I am avoiding using Single Table Inheritance here because the FeedbackOne, FeedbackTwo, FeedbackThree models do not share much common data, so I would end up with a large sparsely populated table with STI.

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  • ruby on rails basics help

    - by CHID
    Hi, i created a scaffolded application in rails by the name of product. The product_controller.rb file contains the following. class ProductsController ApplicationController def new @product = Product.new respond_to do |format| format.html # new.html.erb format.xml { render :xml = @product } end end def create @product = Product.new(params[:product]) respond_to do |format| if @product.save flash[:notice] = 'Product was successfully created.' format.html { redirect_to(@product) } format.xml { render :xml = @product, :status = :created, :location = @product } else format.html { render :action = "new" } format.xml { render :xml = @product.errors, :status = :unprocessable_entity } end end end Now when the url http://localhost:3000/products/create is given Where new product link is clicked, control is transferred to new definition in the controller class and then an instance variable @product is created. BUT WHERE IS THIS VARIABLE PASSED? The funtion inturn calls new.rhtml which contains <% form_for(@product) do |f| % #all form elments declaration <% f.submit "Create" % <%= end % Here @product is initialized in the controller file and passed to this new.rhtml. So where does form_for(@product) gets the data? How does the control gets tranfered to create function in controller file when submit button is clicked? No where action is specified to the controller file. in the create function, wat does redirec_to(@product) specify where @product is an object received from the new.html file... I am very much confused on the basics of ROR. Somone pls help me clarify this. pardon me for making such a big post. I have lots of doubts in this single piece of code

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  • xhtml validator

    - by lolalola
    Hi, why w3 validator show error? "Line 5, Column 7: end tag for "head" which is not finished </head> Most likely, you nested tags and closed them in the wrong order. For example <p><em>...</p> is not acceptable, as <em> must be closed before <p>. Acceptable nesting is: <p><em>...</em></p> Another possibility is that you used an element which requires a child element that you did not include. Hence the parent element is "not finished", not complete. For instance, in HTML the <head> element must contain a <title> child element, lists require appropriate list items (<ul> and <ol> require <li>; <dl> requires <dt> and <dd>), and so on. " My code: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" > <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> </head> <body> Text... </body> </html>

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  • Making a Delete and Reply button in Jquery

    - by Branko Ostojic
    this is my second post on the website. Of all other sites i tried, this one gave the most accurate and useful information! I'm in a bit of a trouble with buttons, i have a task to make an inbox and to add a "reply" and "delete" button into every instance of the message. I was indeed wandering if there is a better way to do that than forcing the HTML code into the script, because every message is dynamically generated. Any help and/or suggestions would be very appreciated!(The objects are called from a JSON file). $(document).ready(function(){ $.getJSON('public/js/data.json', function(json){ $.each(json.data, function(i, data){ var output = ''; if(data.from.id != '234' && data.from.name != 'Alan Ford'){ $("#inbox").append( output += '<div class="post">'+ '<div class="h1">'+data.from.name+' - '+data.subject+'</div>'+ //this gives the name of the person who sent the message and the subject '<div class="content">'+data.message_formatted+'</div>'+ //The content of the message //buttons should be squeezed left of the date //this gives the date of the message sent '<div class="time">'+data.date_sent_formatted.formatted+'</div>'+ '</div>' ); }}); }); }); var date_sent=convertToDateTime(); function delete_message(id){ console.log('Delete message with id: '+id); } function reply_message(id, sender){ console.log('Message id: '+id); console.log('Reply to: '+sender); } The complete code in the JSFiddle . Just copy/pasted!

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  • Passing bundle to activity set as singletask

    - by Falmarri
    So I have a MapActivity that runs an asynchtask that occasionally updates what exactly it's displaying on the map (via a string). I originally pass this string in from the intent when the activity is first created. And then if you click on one of the drawables on the map, it opens a new activity, which can then create a new mapview (same class) with a different string setting. The problem I have is that I only want one instance of the mapview to be running at once. Thus I set android:launchmode="singletask" in the manifest. This works in that it brings the mapactivity to the front, but is there any way to send it a new intent bundle to get a new setting for the string it needs? I tried regetting the extras from the bundle, but it seems to retain the old bundle, not the new intent that was passed to it. I'm not sure I want to do startActivityForResult because the 2nd activity may or may not want to update the original activity. I hope that made sense. I can post code if necessary, but I think that should explain my situation.

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  • C# generics with MVVM, pulling the T out of <T>

    - by bufferz
    My Model is a generic class that contains a (for example) Value property which can be int, float, string, bool, etc. So naturally this class is represented something like Model<T>. For the sake of collections Model<T> implements the interface IModel, although IModel is itself empty of any content. My ViewModel contains and instance of Model<T> and it is passed in through ViewModel's constructor. I still want to know what T is in ViewModel, so when I expose Model to the View I know the datatype of Model's buried Value property. The class for ViewModel ends up looking like the following: class ViewModel<T> { private Model<T> _model; public ViewModel(Model<T> model) { ....blah.... } public T ModelsValue {get; set; } } This works fine, but is limited. So now I need to expose a collection of IModels with varying Ts to my View, so I'm trying to set up an ObservableCollection of new ViewModel<T>s to a changing list of IModels. The problem is, I can't figure out how to get T from Model<T> from IModel to construct ViewModel<T>(Model<T>) at runtime. In the VS2010 debugger I can mouseover any IModel object and see its full Model<int> for example at runtime so I know the data is in there. Any ideas?

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  • Creating 1 page PDF of iPad Screen view - How?

    - by user314695
    Hi All, I've asked this question on a couple other forums and have had zero response, so I'm hoping someone here can help point me in the right direction. I have a pretty simple one screen application for my work. It's basically just a recreation of a 1 page paper report that has a company logo, some labels, a few text boxes and a scroll text box for the report. I need to be able to fill out the report then click a button to save it in a graphical form so I can fax, print or email it later. Currently, I'm just programmatically taking a screen capture and saving it to the photo's library (default for screen capture). Then I can just email it from photo's. This works ok, but is kind of hacky, at best. I've read through the new iPad 3.2 guide for creating PDF's (apparently it's supposed to be much easier than before) but I can not get it to work and I've spent countless hours on it now. I'm hoping someone has the answer for me. Alternatively, if anyone knows how I can redirect where the screen capture is stored (default is in the photo album) then maybe I can make that function work. If I could redirect the screen capture to store in my applications document folder, then I can use MFMailCompose to attach it to an email. Lastly, on a side note, does anyone know of a good way to capture a digital signature via touch. For instance, I'd love to have my users be able to just sign their name via touch at the bottom of the document before I convert to PDF or take a screen capture. Thanks in advance for your help. -Ray

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  • Conditional compilation hackery in C# - is there a way to pull this off?

    - by Chris
    I have an internal API that I would like others to reference in their projects as a compiled DLL. When it's a standalone project that's referenced, I use conditional compilation (#if statements) to switch behavior of a key web service class depending on compilation symbols. The problem is, once an assembly is generated, it appears that it's locked into whatever the compilation symbols were when it was originally compiled - for instance, if this assembly is compiled with DEBUG and is referenced by another project, even if the other project is built as RELEASE, the assembly still acts as if it was in DEBUG as it doesn't need recompilation. That makes sense, just giving some background. Now I'm trying to work around that so I can switch the assembly's behavior by some other means, such as scanning the app/web config file for a switch. The problem is, some of the assembly's code I was switching between are attributes on methods, for example: #if PRODUCTION [SoapDocumentMethodAttribute("https://prodServer/Service_Test", RequestNamespace = "https://prodServer", ResponseNamespace = "https://prodServer")] #else [SoapDocumentMethodAttribute("https://devServer/Service_Test", RequestNamespace = "https://devServer", ResponseNamespace = "https://devServer")] #endif public string Service_Test() { // test service } Though there might be some syntactical sugar that allows me to flip between two attributes of the same type in another fashion, I don't know it. Any ideas? The alternative method would be to reference the entire project instead of the assembly, but I'd rather stick with just referencing the compiled DLL if I can. I'm also completely open to a whole new approach to solve the problem if that's what it takes.

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  • XML Reader threw Object Null exception, but node exists(?!)

    - by Capt.Morgan
    I am hoping someone could enlighten me as to why I am getting the annoying - "xml object reference not set to an instance .." error. The elements (nodes?) I am looking for seem to exist and I have not misspelled it either :[ I might be doing something stupid here, but any help at all would be greatly appreciated. My Code: private void button1_Click(object sender, RoutedEventArgs e) { XmlDocument reader = new XmlDocument(); reader.Load("Kotaku - powered by FeedBurner.xml"); XmlNodeList titles = reader.GetElementsByTagName("title"); XmlNodeList dates = reader.GetElementsByTagName("pubDate"); XmlNodeList descriptions = reader.GetElementsByTagName("description"); XmlNodeList links = reader.GetElementsByTagName("link"); for (int i = 0; i < titles.Count; i++) { textBox1.AppendText(Environment.NewLine + titles[i].InnerText); textBox1.AppendText(Environment.NewLine + descriptions[i].InnerText); //<<-- Throws Object Ref Null Exception textBox1.AppendText(Environment.NewLine + links[i].InnerText); textBox1.AppendText(Environment.NewLine + dates[i].InnerText); //<<-- Throws Object Ref Null Exception } } The XML I am using is a saved XML page from: http://feeds.gawker.com/kotaku/full The way I am working on it now is as follows: I have saved the page from the above link (which is an XML page) and put it next to my EXE for easier access. Then I run the code.

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  • Identifying a class which is extending an abstract class

    - by Simon A. Eugster
    Good Evening, I'm doing a major refactoring of http://wiki2xhtml.sourceforge.net/ to finally get better overview and maintainability. (I started the project when I decided to start programming, so – you get it, right? ;)) At the moment I wonder how to solve the problem I'll describe now: Every file will be put through several parsers (like one for links, one for tables, one for images, etc.): public class WikiLinks extends WikiTask { ... } public class WikiTables extends WikiTask { ... } The files will then be parsed about this way: public void parse() { if (!parse) return; WikiTask task = new WikiLinks(); do { task.parse(this); } while ((task = task.nextTask()) != null); } Sometimes I may want to use no parser at all (for files that only need to be copied), or only a chosen one (e.g. for testing purposes). So before running task.parse() I need to check whether this certain parser is actually necessary/desired. (Perhaps via Blacklist or Whitelist.) What would you suggest for comparing? An ID for each WikiTask (how to do?)? Comparing the task Object itself against a new instance of a WikiTask (overhead)?

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  • Building simple jQuery plugin, need assistance

    - by kirisu_kun
    Hi there, I'm building my first ever jQuery plugin (it's just a simple experiment). Here's what I have so far: (function($){ $.fn.extend({ auchieFader: function(options) { var defaults = { mask: '', topImg : '', } var options = $.extend(defaults, options); return this.each(function() { var o = options; var obj = $(this); var masker = $(o.mask, obj); masker.hover(function () { $(o.topImg).stop().animate({ "opacity": "0" }, "slow"); }, function () { $(o.topImg).stop().animate({ "opacity": "1" }, "slow"); }); }); } }); })(jQuery); I'm then calling the plugin using: $('.fader').auchieFader({mask: ".mask", topImg: ".top"}); If I then add another request say: $('.fader2').auchieFader({mask: ".mask", topImg: ".top"}); Then no matter what instance of my 2 faders I hover both of them will trigger. I know this is because my mask mask and topImg options have the same class - but how can I modify the plugin to allow for these items to have the same class? I know it's probably something really simple, but I'm still finding my way with jQuery and Javascript in general. Any other tips on improving my code would also be greatly appreciated! Cheers, Chris

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  • Can I control object creation using MEF?

    - by Akash
    I need to add some extension points to our existing code, and I've been looking at MEF as a possible solution. We have an IRandomNumberGenerator interface, with a default implementation (ConcreteRNG) that we would like to be swappable. This sounds like an ideal scenario for MEF, but I've been having problems with the way we instantiate the random number generators. Our current code looks like: public class Consumer { private List<IRandomNumberGenerator> generators; private List<double> seeds; public Consumer() { generators = new List<IRandomNumberGenerator>(); seeds = new List<double>(new[] {1.0, 2.0, 3.0}); foreach(var seed in seeds) { generators.Add(new ConcreteRNG(seed); } } } In other words, the consumer is responsible for instantiating the RNGs it needs, including providing the seed that each instance requires. What I'd like to do is to have the concrete RNG implementation discovered and instantiated by MEF (using the DirectoryCatalog). I'm not sure how to achieve this. I could expose a Generators property and mark it as an [Import], but how do I provide the required seeds? Is there some other approach I am missing?

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  • How to differentiate between method and function in a decorator?

    - by defnull
    I want to write a decorator that acts differently depending on whether it is applied to a function or to a method. def some_decorator(func): if the_magic_happens_here(func): # <---- Point of interest print 'Yay, found a method ^_^ (unbound jet)' else: print 'Meh, just an ordinary function :/' return func class MyClass(object): @some_decorator def method(self): pass @some_decorator def function(): pass I tried inspect.ismethod(), inspect.ismethoddescriptor() and inspect.isfunction() but no luck. The problem is that a method actually is neither a bound nor an unbound method but an ordinary function as long as it is accessed from within the class body. What I really want to do is to delay the actions of the decorator to the point the class is actually instantiated because I need the methods to be callable in their instance scope. For this, I want to mark methods with an attribute and later search for these attributes when the .__new__() method of MyClass is called. The classes for which this decorator should work are required to inherit from a class that is under my control. You can use that fact for your solution. In the case of a normal function the delay is not necessary and the decorator should take action immediately. That is why I wand to differentiate these two cases.

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  • xml parameter for soap webservice request in iphone

    - by Jayshree
    Hello everybody. I want to send a soap request to a webservice method. Now i want to send the parameter as an xml input for that request. so plz can anybody give me an idea of how to do it in iphone? Right now i am sending the request in following way : NSString *soapMessage = @"<?xml version=\"1.0\" encoding=\"utf-8\"?>\n" "<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope\">\n" "<soap:Body>\n" "<GetCustomerInfoXML xmlns=\"http://qa2.alliancetek.com/phpwebservice\">\n" "<id><customer><id>1</id></customer></id>" "</GetCustomerInfoXML>" "</soap:Body>\n" "</soap:Envelope>"; NSLog(@"%@",soapMessage); NSURL *url = [NSURL URLWithString:@"http://qa2.alliancetek.com/phpwebservice/index.php"]; NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:url]; NSString *msgLength = [NSString stringWithFormat:@"%d", [soapMessage length]]; [theRequest addValue: @"text/xml; charset=utf-8" forHTTPHeaderField:@"Content-Type"]; [theRequest addValue: @"http://qa2.alliancetek.com/phpwebservice/index.php//GetCustomerInfoXML" forHTTPHeaderField:@"SOAPAction"]; [theRequest addValue: msgLength forHTTPHeaderField:@"Content-Length"]; [theRequest setHTTPMethod:@"POST"]; [theRequest setHTTPBody: [soapMessage dataUsingEncoding:NSUTF8StringEncoding]]; But i want to send the parameters in xml format. so how do i do it????

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  • Ways to make (relatively) safe assumptions about the type of concrete subclasses?

    - by Kylotan
    I have an interface (defined as a abstract base class) that looks like this: class AbstractInterface { public: bool IsRelatedTo(const AbstractInterface& other) const = 0; } And I have an implementation of this (constructors etc omitted): class ConcreteThing { public: bool IsRelatedTo(const AbstractInterface& other) const { return m_ImplObject.has_relationship_to(other.m_ImplObject); } private: ImplementationObject m_ImplObject; } The AbstractInterface forms an interface in Project A, and the ConcreteThing lives in Project B as an implementation of that interface. This is so that code in Project A can access data from Project B without having a direct dependency on it - Project B just has to implement the correct interface. Obviously the line in the body of the IsRelatedTo function cannot compile - that instance of ConcreteThing has an m_ImplObject member, but it can't assume that all AbstractInterfaces do, including the other argument. In my system, I can actually assume that all implementations of AbstractInterface are instances of ConcreteThing (or subclasses thereof), but I'd prefer not to be casting the object to the concrete type in order to get at the private member, or encoding that assumption in a way that will crash without a diagnostic later if this assumption ceases to hold true. I cannot modify ImplementationObject, but I can modify AbstractInterface and ConcreteThing. I also cannot use the standard RTTI mechanism for checking a type prior to casting, or use dynamic_cast for a similar purpose. I have a feeling that I might be able to overload IsRelatedTo with a ConcreteThing argument, but I'm not sure how to call it via the base IsRelatedTo(AbstractInterface) method. It wouldn't get called automatically as it's not a strict reimplementation of that method. Is there a pattern for doing what I want here, allowing me to implement the IsRelatedTo function via ImplementationObject::has_relationship_to(ImplementationObject), without risky casts? (Also, I couldn't think of a good question title - please change it if you have a better one.)

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  • Extensions methods and forward compatibilty of source code.

    - by TcKs
    Hi, I would like solve the problem (now hypothetical but propably real in future) of using extension methods and maginification of class interface in future development. Example: /* the code written in 17. March 2010 */ public class MySpecialList : IList<MySpecialClass> { // ... implementation } // ... somewhere elsewhere ... MySpecialList list = GetMySpecialList(); // returns list of special classes var reversedList = list.Reverse().ToList(); // .Reverse() is extension method /* now the "list" is unchanged and "reveresedList" has same items in reversed order */ /* --- in future the interface of MySpecialList will be changed because of reason XYZ*/ /* the code written in some future */ public class MySpecialList : IList<MySpecialClass> { // ... implementation public MySpecialList Reverse() { // reverse order of items in this collection return this; } } // ... somewhere elsewhere ... MySpecialList list = GetMySpecialList(); // returns list of special classes var reversedList = list.Reverse().ToList(); // .Reverse() was extension method but now is instance method and do something else ! /* now the "list" is reversed order of items and "reveresedList" has same items lake in "list" */ My question is: Is there some way how to prevent this case (I didn't find them)? If is now way how to prevent it, is there some way how to find possible issues like this? If is now way how to find possible issues, should I forbid usage of extension methods? Thanks.

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  • Call 32-bit or 64-bit program from bootloader

    - by user1002358
    There seems to be quite a lot of identical information on the Internet about writing the following 3 bootloaders: Infinite loop jmp $ Print a single character Print "Hello World". This is fantastic, and I've gone through these 3 variations with very little trouble. I'd like to write some 32- or 64-bit code in C and compile it, and call that code from the bootloader... basically a bootloader that, for example, sets the computer up to run some simple numerical simulation. I'll start by listing primes, for example, and then maybe some input/output from the user to maybe compute a Fourier transform. I don't know. I haven't found any information on how to do this, but I can already foresee some problems before I even begin. First of all, compiling a C program compiles it into one of several different files, depending on the target. For Windows, it's a PE file. For Linux, it's a .out file. These files are both quite different. In my instance, the target isn't Windows or Linux, it's just whatever I have written in the bootloader. Secondly, where would the actual code reside? The bootloader is exactly 512 bytes, but the program I write in C will certainly compile to something much larger. It will need to sit on my (virtual) hard disk, probably in some sort of file system (which I haven't even defined!) and I will need to load the information from this file into memory before I can even think about executing it. But from my understanding, all this is many, many orders of magnitude more complex than a 12-line "Hello World" bootloader. So my question is: How do I call a large 32- or 64-bit program (written in C/C++) from my 16-bit bootloader.

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  • RoR ActiveRecord f.select nil method error

    - by sellis6688
    Whenever I use an f.select statement to determine assignment_id(or student_id), and I should get a validation error, I get this error instead of the validation message: You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occurred while evaluating nil.collect Extracted source (around line #11): 8: </p> 9: <p> 10: <%= f.label 'Assignment:' %><br /> 11: <%= f.select(:assignment_id, @assignments.collect {|p| [p.ass_num, p.id]})%> 12: </p> 13: <p> 14: <%= f.label 'First Student:' %><br /> My grades model: class Grade < ActiveRecord::Base has_and_belongs_to_many :students belongs_to :assignment validates_presence_of :score, :assignment_id, :student_id validates_numericality_of :score, :greater_than_or_equal_to => 0, :less_than_or_equal_to => 100, :allow_nil => true validates_uniqueness_of :student_id, :scope => :assignment_id end If I use a text_field, I don't get the error... but there's far too many students for that. Neither @assignments nor @students are nil. Any suggestions?

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  • Many users, many cpus, no delays. Good for cloud?

    - by Eric
    I wish to set up a CPU-intensive time-important query service for users on the internet. A usage scenario is described below. Is cloud computing the right way to go for such an implementation? If so, what cloud vendor(s) cater to this type of application? I ask specifically, in terms of: 1) pricing 2) latency resulting from: - slow CPUs, instance creations, JIT compiles, etc.. - internal management and communication of processes inside the cloud (e.g. a queuing process and a calculation process) - communication between cloud and end user 3) ease of deployment A usage scenario I am expecting is: - A typical user sends a query (XML of size around 1K) once every 30 seconds on average. - Each query requires a numerical computation of average time 0.2 sec and max time 1 sec on a 1 GHz Pentium. The computation requires no data other than the query itself and is performed by the same piece of code each time. - The delay a user experiences between sending a query and receiving a response should be on average no more than 2 seconds and in general no more than 5 seconds. - A background save to a DB of the response should occur (not time critical) - There can be up to 30000 simultaneous users - i.e., on average 1000 queries a second, each requiring an average 0.2 sec calculation, so that would necessitate around 200 CPUs. Currently I'm look at GAE Java (for quicker deployment and less IT hassle) and EC2 (Speed and price optimization) as options. Where can I learn more about the right way to set ups such a system? past threads, different blogs, books, etc.. BTW, if my terminology is wrong or confusing, please let me know. I'd greatly appreciate any help.

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  • Foiled by path-dependent types

    - by Ladlestein
    I'm having trouble using, in one trait, a Parser returned from a method in another trait. The compiler complains of a type mismatch and it appears to me that the problem is due to the path-dependent class. I'm not sure how to get what I want. trait Outerparser extends RegexParsers { def inner: Innerparser def quoted[T](something: Parser[T]) = "\"" ~> something <~ "\"" def quotedNumber = quoted(inner.number) // Compile error def quotedLocalNumber = quoted(number) // Compiles just fine def number: Parser[Int] = ("""[1-9][0-9]*"""r) ^^ {str => str.toInt} } trait Innerparser extends RegexParsers { def number: Parser[Int] = ("""[1-9][0-9]*"""r) ^^ {str => str.toInt} } And the error: [error] /Path/to/MyParser.scala:6: type mismatch [error] found : minerals.Innerparser#Parser[Int] [error] required: Outerparser.this.Parser[?] [error] def quotedNumber = quoted(inner.number) I sort-of get the idea: each "something" method is defining a Parser type whose path is specific to the enclosing class (Outerparser or Innerparser). The "quoted" method of Outerparser expects an an instance of type Outerparser.this.Parser but is getting Innerparser#Parser. I like to be able to use quoted with a parser obtained from this class or some other class. How can I do that?

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  • How can I "reset" styles for a given HTML element?

    - by Sambo
    I am working on an embeddable javascript which inserts HTML elements onto unknown pages. I have no control of the stylesheets of the pages I'll be inserting HTML into. The problem is that the HTML I insert will mistakenly stylized by the page, and I want to prevent that. What's the least verbose and/or resource intensive to go about ensuring the elements I insert are exactly as I'd like them to be? Is there an easy way to clear all styling for a given HTML element and children? In firebug, for instance, you can remove all styling. I feel like there must, and the very least should, be a native way to exempt certain HTML elements from stylesheet rules? Example: var myHTML = $("<div>my html in here</div>"); myHTML.resetAllStyles(); //<--- what would this function do? myHTML.appendTo("body"); I really want to avoid explicitly stating the attributes I want for each element I insert... PS: I have a lot of experience with JS and CSS, so you can assume that I'll understand pretty much anything you're going to tell me.

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