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  • Ruby IRB - Requires and Scope

    - by tyndall
    Trying to understand this problem I'm running into. I create file welcome.rb. The contents of this file: welcome_message = "hi there" I then launch an irb session. And type require 'welcome'. That works fine. Then I type: puts welcome_message I get the error message undefined local variable or method `welcome_message' for main:Object What is the best way to bring in predefined variables and have initialization work done when you require something into your irb session. Global variables didn't seem like the right path.

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  • Loading SpriteFont through a different class than Game.cs

    - by MintyAnt
    I am trying to load up a single SpriteFont to print some debug information. In our current game, we load up both Textures and Music through a ResourceManager. They are both loaded with a filestream, and thus do not require Content.Load SoundEffect soundEffect = SoundEffect.FromStream( fs ); Since this ResourceManager does not inherit from Game or is like Game.cs, I cannot use the usual method: SpriteFont spriteFont = Content.Load<SpriteFont>(resource.Key.Item2); Anyone have any idea how I can either: -Load the SpriteFont a different way -Create my own Contentmanager

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  • Proper way in Python to raise errors while setting variables

    - by ensnare
    What is the proper way to do error-checking in a class? Raising exceptions? Setting an instance variable dictionary "errors" that contains all the errors and returning it? Is it bad to print errors from a class? Do I have to return False if I'm raising an exception? Just want to make sure that I'm doing things right. Below is some sample code: @property def password(self): return self._password @password.setter def password(self,password): # Check that password has been completed try: # Check that password has a length of 6 characters if (len(password) < 6): raise NameError('Your password must be greater \ than 6 characters') except NameError: print 'Please choose a password' return False except TypeError: print 'Please choose a password' return False #Set the password self._password = password #Encrypt the password password_md5 = md5.new() password_md5.update(password) self._password_md5 = password_md5.hexdigest()

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  • OBJ-C: Call an instance of core-plot graph from separate view controller

    - by Kevin
    I'm using a view controller i.e. ViewController:UIViewController and have another class GraphViewController:UIViewController . How do I call an instance of GraphViewController and place it into my ViewController? I am currently trying to call the plot within my ViewController directly, but I want to make the graph modular so I don't have to copy code if I use the same graph again. ViewController has methods -(void) refreshGraph; //Inhereted Methods -(NSUInteger)numberOfRecordsForPlot:(CPPlot *)plot; -(NSNumber *)numberForPlot:(CPPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index; How do I move these methods to a separate class and then call it to get the same plot in my ViewController? I am sure there must be a thread on this somewhere but I can't seem to find it.

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  • Creating a castable entity class wrapper

    - by Tony
    Hi I need to have a wrapper class that exposes some properties of my entity class called ProfileEntity. I tried doing it by deriving from this entity and then creating properties that return specific entity properties, but it says I cannot cast from ProfileEntity to ProfileEntityWrapper. When I try to put the return values of a method that returns a 'ProfileEntity' into the wrapper I get the above error. How do I create such a wrapper class that is castable? Example class ProfileEntityWrapper : ProfileEntity { public string Name { get { return this.ProfileEntityName; } } public class Someclass { public ProfileEntity SomeMethod() { return ProfileEntity; // example of method returning this object } } public class SomeOtherlClass { SomeClass sc = new SomeClass(); public void DoSomething() { ProfileEntityWrapper ew = (ProfileEntityWrapper)sc.SomeMethod(); // Cannot do this cast!!! } }

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  • How to find minimum of nonlinear, multivariate function using Newton's method (code not linear algeb

    - by Norman Ramsey
    I'm trying to do some parameter estimation and want to choose parameter estimates that minimize the square error in a predicted equation over about 30 variables. If the equation were linear, I would just compute the 30 partial derivatives, set them all to zero, and use a linear-equation solver. But unfortunately the equation is nonlinear and so are its derivatives. If the equation were over a single variable, I would just use Newton's method (also known as Newton-Raphson). The Web is rich in examples and code to implement Newton's method for functions of a single variable. Given that I have about 30 variables, how can I program a numeric solution to this problem using Newton's method? I have the equation in closed form and can compute the first and second derivatives, but I don't know quite how to proceed from there. I have found a large number of treatments on the web, but they quickly get into heavy matrix notation. I've found something moderately helpful on Wikipedia, but I'm having trouble translating it into code. Where I'm worried about breaking down is in the matrix algebra and matrix inversions. I can invert a matrix with a linear-equation solver but I'm worried about getting the right rows and columns, avoiding transposition errors, and so on. To be quite concrete: I want to work with tables mapping variables to their values. I can write a function of such a table that returns the square error given such a table as argument. I can also create functions that return a partial derivative with respect to any given variable. I have a reasonable starting estimate for the values in the table, so I'm not worried about convergence. I'm not sure how to write the loop that uses an estimate (table of value for each variable), the function, and a table of partial-derivative functions to produce a new estimate. That last is what I'd like help with. Any direct help or pointers to good sources will be warmly appreciated. Edit: Since I have the first and second derivatives in closed form, I would like to take advantage of them and avoid more slowly converging methods like simplex searches.

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  • Django Querying Relation of Relation

    - by Brent
    I'm stuck on a Django ORM issue that is bugging me. I have a set of models linked by a foreign key but the requirements are a bit odd. I need to list items by their relation's relation. This is hard to explain so I've tried to depict this below, given: Work ManyToMany(Award) Award ForeignKey(AwardCategory) AwardCategory I need to list work items so they are listed by the award category. Desired output would be: Work Instance A Award Instance A that belongs to Award Category Instance A Award Instance C that belongs to Award Category Instance A Award Instance G that belongs to Award Category Instance A Work Instance A (same instance as above, but listed by different award__category) Award Instance F that belongs to Award Category Instance B Award Instance R that belongs to Award Category Instance B Award Instance Z that belongs to Award Category Instance B Work Instance B Award Instance B that belongs to Award Category Instance A Award Instance A that belongs to Award Category Instance A Essentially I want to list all work by the award category. I can get this to work in part but my solution is filthy and gross. I'm wondering if there is a better way. I considered using a ManyToMany and a through attribute but I'm not certain if I'm utilizing it correctly.

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  • Operator overloading C++ outside class

    - by bobobobo
    Well, so there are 2 ways to overload operators for a C++ class INSIDE CLASS class Vector2 { public: float x, y ; Vector2 operator+( const Vector2 & other ) { Vector2 ans ; ans.x = x + other.x ; ans.y = y + other.y ; return ans ; } } ; OUTSIDE CLASS class Vector2 { public: float x, y ; } ; Vector2 operator+( const Vector2& v1, const Vector2& v2 ) { Vector2 ans ; ans.x = v1.x + v2.x ; ans.y = v1.y + v2.y ; return ans ; } In C# apparently you can only use the OUTSIDE class method The question is, in C++, which is "morer-correcter?" Which is preferable? When is one way better than another?

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  • Catching an exception class within a template

    - by Todd Bauer
    I'm having a problem using the exception class Overflow() for a Stack template I'm creating. If I define the class regularly there is no problem. If I define the class as a template, I cannot make my call to catch() work properly. I have a feeling it's simply syntax, but I can't figure it out for the life of me. #include<iostream> #include<exception> using namespace std; template <class T> class Stack { private: T *stackArray; int size; int top; public: Stack(int size) { this->size = size; stackArray = new T[size]; top = 0; } ~Stack() { delete[] stackArray; } void push(T value) { if (isFull()) throw Overflow(); stackArray[top] = value; top++; } bool isFull() { if (top == size) return true; else return false; } class Overflow {}; }; int main() { try { Stack<double> Stack(5); Stack.push( 5.0); Stack.push(10.1); Stack.push(15.2); Stack.push(20.3); Stack.push(25.4); Stack.push(30.5); } catch (Stack::Overflow) { cout << "ERROR! The stack is full.\n"; } return 0; } The problem is in the catch (Stack::Overflow) statement. As I said, if the class is not a template, this works just fine. However, once I define it as a template, this ceases to work. I've tried all sorts of syntaxes, but I always get one of two sets of error messages from the compiler. If I use catch(Stack::Overflow): ch18pr01.cpp(89) : error C2955: 'Stack' : use of class template requires template argument list ch18pr01.cpp(13) : see declaration of 'Stack' ch18pr01.cpp(89) : error C2955: 'Stack' : use of class template requires template argument list ch18pr01.cpp(13) : see declaration of 'Stack' ch18pr01.cpp(89) : error C2316: 'Stack::Overflow' : cannot be caught as the destructor and/or copy constructor are inaccessible EDIT: I meant If I use catch(Stack<double>::Overflow) or any variety thereof: ch18pr01.cpp(89) : error C2061: syntax error : identifier 'Stack' ch18pr01.cpp(89) : error C2310: catch handlers must specify one type ch18pr01.cpp(95) : error C2317: 'try' block starting on line '75' has no catch handlers I simply can not figure this out. Does anyone have any idea?

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  • Mock static method Activator.CreateInstance to return a mock of another class

    - by Jeep87c
    I have this factory class and I want to test it correctly. Let's say I have an abstract class which have many child (inheritance). As you can see in my Factory class the method BuildChild, I want to be able to create an instance of a child class at Runtime. I must be able to create this instance during Runtime because the type won't be know before runtime. And, I can NOT use Unity for this project (if so, I would not ask how to achieve this). Here's my Factory class that I want to test: public class Factory { public AnAbstractClass BuildChild(Type childType, object parameter) { AnAbstractClass child = (AnAbstractClass) Activator.CreateInstance(childType); child.Initialize(parameter); return child; } } To test this, I want to find a way to Mock Activator.CreateInstance to return my own mocked object of a child class. How can I achieve this? Or maybe if you have a better way to do this without using Activator.CreateInstance (and Unity), I'm opened to it if it's easier to test and mock! I'm currently using Moq to create my mocks but since Activator.CreateInstance is a static method from a static class, I can't figure out how to do this (I already know that Moq can only create mock instances of objects). I took a look at Fakes from Microsoft but without success (I had some difficulties to understand how it works and to find some well explained examples). Please help me! EDIT: I need to mock Activator.CreateInstance because I want to force this method to return another mocked object. The correct thing I want is only to stub this method (not to mock it). So when I test BuildChild like this: [TestMethod] public void TestBuildChild() { var mockChildClass = new Mock(AChildClass); // TODO: Stub/Mock Activator.CreateInstance to return mockChildClass when called with "type" and "parameter" as follow. var type = typeof(AChildClass); var parameter = "A parameter"; var child = this._factory.BuildChild(type, parameters); } Activator.CreateInstance called with type and parameter will return my mocked object instead of creating a new instance of the real child class (not yet implemented).

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  • Is there a way to circumvent Python list.append() becoming progressively slower in a loop as the lis

    - by Deniz
    I have a big file I'm reading from, and convert every few lines to an instance of an Object. Since I'm looping through the file, I stash the instance to a list using list.append(instance), and then continue looping. This is a file that's around ~100MB so it isn't too large, but as the list grows larger, the looping slows down progressively. (I print the time for each lap in the loop). This is not intrinsic to the loop ~ when I print every new instance as I loop through the file, the program progresses at constant speed ~ it is only when I append them to a list it gets slow. My friend suggested disabling garbage collection before the while loop and enabling it afterward & making a garbage collection call. Did anyone else observe a similar problem with list.append getting slower? Is there any other way to circumvent this?

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  • How to access "overridden" inner class in Scala?

    - by doom2.wad
    I have two traits, one extending the other, each with an inner class, one extending the other, with the same names: trait A { class X { def x() = doSomething() } } trait B extends A { class X extends super.X { override def x() = doSomethingElse() } } class C extends B { val x = new X() // here B.X is instantiated val y = new A.X() // does not compile val z = new A.this.X() // does not compile } How do I access A.X class in the C class's body? Renaming B.X not to hide A.X is not a preferred way. To make things a bit complicated, in the situation I have encountered this problem the traits have type parameters (not shown in this example).

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  • Inherit a parent class docstring as __doc__ attribute

    - by Reinout van Rees
    There is a question about Inherit docstrings in Python class inheritance, but the answers there deal with method docstrings. My question is how to inherit a docstring of a parent class as the __doc__ attribute. The usecase is that Django rest framework generates nice documentation in the html version of your API based on your view classes' docstrings. But when inheriting a base class (with a docstring) in a class without a docstring, the API doesn't show the docstring. It might very well be that sphinx and other tools do the right thing and handle the docstring inheritance for me, but django rest framework looks at the (empty) .__doc__ attribute. class ParentWithDocstring(object): """Parent docstring""" pass class SubClassWithoutDoctring(ParentWithDocstring): pass parent = ParentWithDocstring() print parent.__doc__ # Prints "Parent docstring". subclass = SubClassWithoutDoctring() print subclass.__doc__ # Prints "None" I've tried something like super(SubClassWithoutDocstring, self).__doc__, but that also only got me a None.

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  • Rails, if instance is in a scope?

    - by Joseph Silvashy
    I using rails 3 and I can't seem to check if a given instance is in a scope, see here: p = Post.find 6 +----+----------+-------------------------+-------------------------+-------------------------+-----------+ | id | title | publish_date | created_at | updated_at | published | +----+----------+-------------------------+-------------------------+-------------------------+-----------+ | 6 | asfdfdsa | 2010-03-28 22:33:00 UTC | 2010-03-28 22:33:46 UTC | 2010-03-28 22:33:46 UTC | true | +----+----------+-------------------------+-------------------------+-------------------------+-----------+ I have a menu scope which looks like: scope :menu, where("published != ?", false).limit(4) When I run it I get: Post.menu.all +----+------------------+------------------+------------------+-------------------+-----------+ | id | title | publish_date | created_at | updated_at | published | +----+------------------+------------------+------------------+-------------------+-----------+ | 1 | Lorem ipsum | 2010-03-23 07... | 2010-03-23 07... | 2010-03-28 21:... | true | | 2 | fdasf | 2010-03-28 21... | 2010-03-28 21... | 2010-03-28 21:... | true | | 3 | Ruby’s Imple... | 2010-03-28 21... | 2010-03-28 21... | 2010-03-28 21:... | true | | 4 | dsaD | 2010-03-28 22... | 2010-03-28 22... | 2010-03-28 22:... | true | +----+------------------+------------------+------------------+-------------------+-----------+ Which is correct, but if I try to check if p is in the the menu scope using: Post.menu.exists?(p) I get true when it should be false What is the proper way to find out if a given instance of something is in a scope?

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  • First class language in Visual Studio 2010 using F#

    - by Aamir Hasan
     F# is a strongly-typed language like C#.It is light weight syntax just like Python.It give you math-like feel. let data = (1,2,3)   let rotations (x, y, z) =     [ (x, y, z);       (z, x, y);       (y, z, x) ]   let derivative f x =     let p1 = f (x - 0.05)     let p2 = f (x + 0.05)     (p2 - p1) / 0.1   let f x = 2.0*x*x - 6.0*x + 3.0   let df = derivative f   System.Console.WriteLine("The derivative of f at x=4 is {0}", df 4.0)   This program will print: “The derivative of f at x=4 is 10”That’s a quick look at just a few of the exciting features of F#.  For more on F#, visit the F# Development Center on MSDN.  

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  • c# class naming standards/guidelines

    - by Ben
    Over the years I've used various naming conventions for services in my applications for example: [ClassName]Service [ClassName]Manager [ClassName]Factory [ClassName]Provider [ClassName]Helper I generally only use the "Helper" suffix for utility classes that have no external dependencies. However I find that there is a bit of a cross-over between the others, and wondered if there was any recommendations/standards/guidelines on what to use and when?

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  • (iPhone SDK) How to link instance variables to a specific UILabel

    - by Timbo
    I'm using the iPhone SDK to build a simple application. I've created a brand new class which has a single variable. I need to make 5 instances of that class, which I have no trouble doing. I can create those instances and also set the variables without issue. What i do need to know is this: How do I link each of the 5 different instances of the variable to different and specific UILabels? Would I be better to create a method that dynamically creates and positions the labels? Thanks for your help in advance, I'm now to this iphone programming thing. I'm serious about learning fast though so I have posted a bounty on this question here : http://www.askearn.com/Responses.aspx?QuestionID=6542613f-7be8-4bb3-a950-aac218d47711

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  • C# Class Design Question

    - by Soo
    This is a super newbie question, I've been programming for a while, but am just learning OOP. I have a class that works with user input via the C# console. There are different methods in this class to gather different input sets. I have another class that takes these input sets and puts them in a database. What is the best way to pass the input from my input class to my database insert class? My guess would be: Array1[] = inputClass.GetParameterSet1(); DatabaseInsertClass.InsertIntoDatabase1(Array1[]); Is there anything wrong with this or is there a better way to do this? Should I even have two classes (The database class could also take the user input)?

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  • ASP.NET Error when referencing a code-behind variable

    - by mattgcon
    I have an aspx page that is supposed to reference a code-behind variable but I am receiving an error of "The name [variable] does not exist in the current context" Here is the aspx code <%@ Control Language="C#" AutoEventWireup="true" Inherits="IPAM.Website.Controls.controls_event_header" Codebehind="event_header.ascx.cs" %> <%# strEventLink %> <h3><%# strEventDate %></h3> <%# strLinks %> Here is part of the aspx.cs code declaring those variables: public string strEventLink = ""; public string strEventDate; public string strLinks = ""; Here is the part of the aspx.cs code where it sets those variables: strEventLink = "<h2>" + parent.Name + "</h2>"; strLinks += "<p><font size=\"+1\"><a href=\"" + Page.ResolveUrl("~" + strScheduleLink) + "\"><b>" + strScheduleLinkText + "</b></a></font></p>\n"; strEventDate = ei.DateSpan; Please help me with this problem

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  • Passing an instance variable through RJS?

    - by Elliot
    Hey guys here is my code (roughly): books.html.erb <% @books.each do |book| %> <% @bookid = book.id %> <div id="enter_stuff"> <%= render "input", :bookid => @bookid %> </div> <%end%> _input.html.erb <% @book = Book.find_by_id(@bookid) %> <strong>your book is: <%=h @book.name %></strong> create.rjs page.replace_html :enter_stuff, :partial => 'input', :object => @bookid The problem here is that only create.js doesn't seem to work (though, if instead of passing the partial I passed "..." it does work, so I know its that there are instance variables in the partial that aren't being reset. Any ideas?) So the final question, is how do I pass an instance variable to a partial through the create.rjs file? p.s. I know I will have duplicate div IDs, I'm not worrying about that for now though. Best, Elliot

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  • Use of Java constructors in persistent entities

    - by Mr Morgan
    Hello I'm new to JPA and using persistence in Java anyway and I have two questions I can't quite work out: I have generated tags as: @JoinColumn(name = "UserName", referencedColumnName = "UserName") @ManyToOne(optional = false) private User userName; @JoinColumn(name = "DatasetNo", referencedColumnName = "DatasetNo") @ManyToOne(optional = false) private Dataset datasetNo; But in one of the constructors for the class, no reference is made to columns UserName or DatasetNo whereas all other columns in the class are referenced in the constructor. Can anyone tell me why this is? Both columns UserName and DatasetNo are 'foreign keys' on the entity Visualisation which corresponds to a database table of the same name. I can't quite work out the ORM. And when using entity classes, or POJO, is it better to have class variables like: private User userName; Where an instance of a class is specified or simply the key of that class instance like: private String userName; Thanks Mr Morgan.

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  • python, wrapping class returning the average of the wrapped members

    - by João Portela
    The title isn't very clear but I'll try to explain. Having this class: class Wrapped(object): def method_a(self): # do some operations return n def method_b(self): # also do some operations return n I wan't to have a class that performs the same way as this one: class Wrapper(object): def __init__(self): self.ws = [Wrapped(1),Wrapped(2),Wrapped(3)] def method_a(self): results=[Wrapped.method_a(w) for w in self.ws] sum_ = sum(results,0.0) average = sum_/len(self.ws) return average def method_b(self): results=[Wrapped.method_b(w) for w in self.ws] sum_ = sum(results,0.0) average = sum_/len(self.ws) return average obviously this is not the actual problem at hand (it is not only two methods), and this code is also incomplete (only included the minimum to explain the problem). So, what i am looking for is a way to obtain this behavior. Meaning, whichever method is called in the wrapper class, call that method for all the Wrapped class objects and return the average of their results. Can it be done? how? Thanks in advance. ps-didn't know which tags to include...

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