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  • Learning Java, how to type text on canvas?

    - by Voley
    I'm reading a book by Eric Roberts - Art and science of java and it got an excersise that I can't figure out - You have to make calendar, with GRect's, 7 by 6, that goes ok, the code part is easy, but also you have to type the numbers of the date on those rectangles, and it's kinda hard for me, there is nothing about it in the book. I tried using GLabel thing, but here arises the problem that I need to work on those numbers, and it says "can't convert from int to string and vice versa". GLabel (string, posX, posY) - it is not accepting int as a parameter, only string, I even tried typecasting, still not working. For example I want to make a loop int currentDate = 1; while (currentDate < 31) { add(new Glabel(currentDate, 100, 100); currentDate++; This code is saying that no man, can't convert int to string. If i try changing currentDate to string, it works, but I got a problem with calculation, as I can't manipulate with number in string, it doesn't even allow to typecast it into int. How can I fix it? Maybe there is another class or method to type the text over those rectangles? I know about println but it doen't have any x or y coordinates, so I can't work with it. And I think it's only for console programs.

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  • Link error for user defined class type template parameter

    - by isurulucky
    Hi, I implemented a Simple STL map in C++. Factored out the comparison as a type as I was instructed to, then implemented the comparison as shown below: template <typename T> int KeyCompare<T>::operator () (T tKey1, T tKey2) { if(tKey1 < tKey2) return -1; else if(tKey1 > tKey2) return 1; else return 0; } here, tKey1 and tKet2 are the two keys I'm comparing. This worked well for all the basic data types and string. I added a template specialization to compare keys of a user defined type named Test and added a specialization as follows: int KeyCompare<Test>::operator () (Test tKey1, Test tKey2) { if(tKey1.a < tKey2.a) return -1; else if(tKey1.a > tKey2.a) return 1; else return 0; } when I run this, I get a linking error saying SimpleMap.obj : error LNK2005: "public: int __thiscall KeyCompare::operator()(class Test,class Test)" (??R?$KeyCompare@VTest@@@@QAEHVTest@@0@Z) already defined in MapTest.obj SimpleMap.obj : error LNK2005: "public: __thiscall KeyCompare::~KeyCompare(void)" (??1?$KeyCompare@VTest@@@@QAE@XZ) already defined in MapTest.obj SimpleMap.obj : error LNK2005: "public: __thiscall KeyCompare::KeyCompare(void)" (??0?$KeyCompare@VTester@@@@QAE@XZ) already defined in MapTest.obj MapTest.cpp is the test harness class in which I wrote the test case. I have used include guards as well, to stop multiple inclusions. Any idea what the matter is?? Thank you very much!!

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  • Heroku: Postgres type operator error after migrating DB from MySQL

    - by sevennineteen
    This is a follow-up to a question I'd asked earlier which phrased this as more of a programming problem than a database problem. http://stackoverflow.com/questions/2935985/postgres-error-with-sinatra-haml-datamapper-on-heroku I believe the problem has been isolated to the storage of the ID column in Heroku's Postgres database after running db:push. In short, my app runs properly on my original MySQL database, but throws Postgres errors on Heroku when executing any query on the ID column, which seems to have been stored in Postgres as TEXT even though it is stored as INT in MySQL. My question is why the ID column is being created as INT in Postgres on the data transfer to Heroku, and whether there's any way for me to prevent this. Here's the output from a heroku console session which demonstrates the issue: Ruby console for myapp.heroku.com >> Post.first.title => "Welcome to First!" >> Post.first.title.class => String >> Post.first.id => 1 >> Post.first.id.class => Fixnum >> Post[1] PostgresError: ERROR: operator does not exist: text = integer LINE 1: ...", "title", "created_at" FROM "posts" WHERE ("id" = 1) ORDER... ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts. Query: SELECT "id", "name", "email", "url", "title", "created_at" FROM "posts" WHERE ("id" = 1) ORDER BY "id" LIMIT 1 Thanks!

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  • Calling Base Class Functions with Inherited Type

    - by Kein Mitleid
    I can't describe exactly what I want to say but I want to use base class functions with an inherited type. Like I want to declare "Coord3D operator + (Coord3D);" in one class, but if I use it with Vector3D operands, I want it to return Vector3D type instead of Coord3D. With this line of code below, I add two Vector3D's and get a Coord3D in return, as told to me by the typeid().name() function. How do I reorganize my classes so that I get a Vector3D on return? #include <iostream> #include <typeinfo> using namespace std; class Coord3D { public: float x, y, z; Coord3D (float = 0.0f, float = 0.0f, float = 0.0f); Coord3D operator + (Coord3D &); }; Coord3D::Coord3D (float a, float b, float c) { x = a; y = b; z = c; } Coord3D Coord3D::operator+ (Coord3D &param) { Coord3D temp; temp.x = x + param.x; temp.y = y + param.y; temp.z = z + param.z; return temp; } class Vector3D: public Coord3D { public: Vector3D (float a = 0.0f, float b = 0.0f, float c = 0.0f) : Coord3D (a, b, c) {}; }; int main () { Vector3D a (3, 4, 5); Vector3D b (6, 7, 8); cout << typeid(a + b).name(); return 0; }

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  • Strange error(dereferencing pointer to incomplete type)

    - by SMiX
    void get_cwd(char* buf) { char *result; current->fs->pwd; result = get_dentry_path(current->fs->pwd); memcpy(buf, result, strlen(result)+1); kfree(result); } error: dereferencing pointer to incomplete type The error points to current-fs-pwd; includes: #include <asm/stat.h> #include <linux/fs.h> #include <linux/file.h> #include <linux/module.h> #include <linux/kernel.h> #include <linux/string.h> #include <linux/dirent.h> #include <linux/sched.h> #include <asm/uaccess.h> #include <asm/current.h> #include <linux/path.h> If I type current-fs; on 5th line gcc don't give error on this line. The problem is with pwd field.

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  • Wrong label for a nodereference in Drupal content-type

    - by MPD
    We have a content-type built using CCK. One of the fields is a node reference. The node picker is using a view to build the options. A few days ago, everything was working well. Today, it looks like all node reference fields using views to populate the selection options are displaying the wrong label. Every single label in the option is ``A'', but the actual node number is correct. The form actually works, just the labels are incorrect. We have tried just about every combination of edit/save, disable/enable, reboot, clear cache, clone the view, rebuild the view, new view, etc, but we still have a big list of As. If we create a brand new content type with a brand new node reference field, we get the problem. Through some backup/restore exercises, we have determined that the problem is actually in the database and not in the code. We can restore our last good backup, but we will lose a decent amount of work we have put into other parts of the database. We enabled mysql query logging, and the view is actually being called properly, but we cannot track down where the problem is creeping in after that (unraveling the CCK / Views / Drupal plumbing is a challenge). The install was build with latest stable versions as of April. The problems referred to in http://drupal.org/node/624422 is similar, but our code versions include the patches mentioned. Any ideas would be appreciated. Thanks.

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  • Generic Constraints And Type Parameters Mess

    - by Dummy01
    Hi everyone, I have the following base abstract class defined as: public abstract class BaseObject<T> : IComparable, IComparable<T>, IEquatable<T> {} I also have an interface defined as: public interface ICode<T> where T : struct { T Code { get; } } Now I want to derive a class that is inherited from BaseObject<T> and includes interface ICode<T>. I tried to define it like that: public class DerivedObject<T, U> : BaseObject<T>, ICode<U> where T : DerivedObject<T, U> where U : struct { public DerivedObject(U code) { Code = code; } // From BaseObject protected override int InstanceCompareTo(T obj) { return Code.CompareTo(obj.Code); } // From BaseObject protected override bool InstanceEquals(T obj) { return Code.Equals(obj.Code); } // From ICode U _Code; public U Code { get { return _Code; } protected set { _Code = value; } } } The only error that comes from the compiler is for Code.CompareTo(obj.Code) with the message: 'U' does not contain a definition for 'CompareTo' and no extension method 'CompareTo' accepting a first argument of type 'U' could be found. But U is a value type and should know CompareTo. Have you any idea what I am doing wrong, or if I do all wrong? My final aim is to derive classes such these: public class Account : DerivedObject<Account, int> public class ItemGroup : DerivedObject<ItemGroup, string> Big Thanks In Advance!

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  • Applying a function to a custom type in F#

    - by Frederik Wordenskjold
    On my journey to learning F#, I've run into a problem I cant solve. I have defined a custom type: type BinTree = | Node of int * BinTree * BinTree | Empty I have made a function which takes a tree, traverses it, and adds the elements it visits to a list, and returns it: let rec inOrder tree = seq{ match tree with | Node (data, left, right) -> yield! inOrder left yield data; yield! inOrder right | Empty -> () } |> Seq.to_list; Now I want to create a function, similar to this, which takes a tree and a function, traverses it and applies a function to each node, then returns the tree: mapInOrder : ('a -> 'b) -> 'a BinTree -> 'b BinTree This seems easy, and it probably is! But I'm not sure how to return the tree. I've tried this: let rec mapInOrder f tree = match tree with | Node(data, left, right) -> mapInOrder f left Node(f(data), left, right) mapInOrder f right | Empty -> () but this returns a unit. I havent worked with custom types before, so I'm probably missing something there!

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  • addField type image and thumbnail path

    - by Christiaan
    Hello, I have a Magento webshop and just created a custom module with the extension (Modulecreator). This module comes with a standard admin interface that can handle file uploads. I found out that if you want to show thumbnails you can use the 'image' field type (addField('myfield', 'image')) instead of the 'file' type field. But now i've got a problem. When I upload files, I save them in a subdirectory called 'slides' in the 'media' directory. But when I edit the item, the image path for the thumbnail next to the uploadfield is set to the 'media' folder. Not my folder as I set it to 'media/slides/'. I use the following code: $fieldset->addField('filename', 'image', array( 'label' => Mage::helper('slideshow')->__('File'), 'required' => true, 'name' => 'filename', )); I tried to set a 'path' key in the array, but this doesn't get picked up by Magento. Hate the lack of support for good and easy to use documentation by Magento... Maybe you can help me out to find a solution?

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  • Mongodb - how to deserialze when a property has an Interface return type

    - by Mark Kelly
    I'm attempting to avoid introducing any dependencies between my Data layer and client code that makes use of this layer, but am running into some problems when attempting to do this with Mongo (using the MongoRepository) MongoRepository shows examples where you create Types that reflect your data structure, and inherit Entity where required. Eg. [CollectionName("track")] public class Track : Entity { public string name { get; set; } public string hash { get; set; } public Artist artist { get; set; } public List<Publish> published {get; set;} public List<Occurence> occurence {get; set;} } In order to make use of these in my client code, I'd like to replace the Mongo-specific types with Interfaces, e.g: [CollectionName("track")] public class Track : Entity, ITrackEntity { public string name { get; set; } public string hash { get; set; } public IArtistEntity artist { get; set; } public List<IPublishEntity> published {get; set;} public List<IOccurenceEntity> occurence {get; set;} } However, the Mongo driver doesn't know how to treat these interfaces, and I understandably get the following error: An error occurred while deserializing the artist property of class sf.data.mongodb.entities.Track: No serializer found for type sf.data.IArtistEntity. --- MongoDB.Bson.BsonSerializationException: No serializer found for type sf.data.IArtistEntity. Does anyone have any suggestions about how I should approach this?

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  • How to specify generic method type parameters partly

    - by DNNX
    I have an extension method like below: public static T GetValueAs<T, R>(this IDictionary<string, R> dictionary, string fieldName) where T : R { R value; if (!dictionary.TryGetValue(fieldName, out value)) return default(T); return (T)value; } Currently, I can use it in the following way: var dictionary = new Dictionary<string, object(); //... var list = dictionary.GetValueAs<List<int, object("A"); // this may throw ClassCastException - this is expected behavior; It works pretty fine, but the second type parameter is really annoying. Is it possible in C# 4.0 rewrite GetValueAs is such a way that the method will still be applicable to different types of string-keyed dictionaries AND there will be no need to specify second type parameter in the calling code, i.e. use var list = dictionary.GetValueAs<List<int("A"); or at least something like var list = dictionary.GetValueAs<List<int, ?("A"); instead of var list = dictionary.GetValueAs<List<int, object("A");

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  • OnClickListener cannot be resolved to a type

    - by Webnet
    I'm diving into Java (this is day 1) and I'm trying to create a button that will trigger a notification when I click it... This code is based off of the notification documentation here, and UI events documentation here package com.example.contactwidget; import android.app.Activity; import android.app.Notification; import android.app.NotificationManager; import android.app.PendingIntent; import android.content.Context; import android.content.Intent; import android.os.Bundle; import android.widget.Button; public class ContactWidget extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Button calc1 = (Button) findViewById(R.id.calc_button_1); calc1.setOnClickListener(buttonListener); setContentView(R.layout.main); } private static final int HELLO_ID = 1; //Error: OnClickListener cannot be resolved to a type private OnClickListener buttonListener = new OnClickListener() { public void onClick (View v) { String ns = Context.NOTIFICATION_SERVICE; NotificationManager mNotificationManager = (NotificationManager) getSystemService(ns); int icon = R.drawable.icon; CharSequence ticketBrief = "Button Pressed Brief"; CharSequence ticketTitle = "Button pressed"; CharSequence ticketText = "You pressed button 1"; long when = System.currentTimeMillis(); Notification notification = new Notification(icon, ticketBrief, when); Intent notificationIntent = new Intent(this, ContactWidget.class); PendingIntent contentIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0); notification.setLatestEventInfo(getApplicationContext(), ticketTitle, ticketText, contentIntent); mNotificationManager.notify(HELLO_ID, notification); } } } I'm running into a problem: OnClickListener cannot be resolved to a type. The problem here is that I don't see any problems with my code in relation to the example I'm using

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  • Xml Conversion "Type mismatch" Error

    - by prema
    I am selecting a query in sql server 2005 SELECT 'Region' AS ELEMENT,(SELECT GeographyName,GeoID from @tmpTable FOR XML RAW, TYPE) FOR XML RAW('Root') This will give the output in xml as <Root ELEMENT="Region"> <row GeographyName="East" GeoID="2" /> <row GeographyName="West" GeoID="3" /> <row GeographyName="North" GeoID="4" /> <row GeographyName="South" GeoID="5" /> </Root> In aspx page, i want to get this function Populatedata(obj, val) { var xmlDom = new JXmlDom(obj, false); --> at this point i am getting error var nodeHeader = xmlDom.selectNodes("//row"); // my code goes here } function JXmlDom (xml,isFile) { this.load=load; this.loadXML=loadXML; this.selectNodes=selectNodes; this.text=text; this.selectSingleNode=selectSingleNode; this.documentElement=documentElement; this.transformNode=transformNode; if (isFile) { this.dom=this.load (xml); }else { this.dom=this.loadXML (xml); } function loadXML (xml) { if (window.ActiveXObject) { var dom=new ActiveXObject("Microsoft.XMLDOm"); dom.async=false; dom.loadXML (xml); } if (document.implementation && document.implementation.createDocument) { var domParser=new DOMParser(); var dom=domParser.parseFromString (xml,"text/xml"); } return dom; } But when i am calling this i am getting an error as Type mismatch.Can anyone help me

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  • Render different view depending on the type of the data

    - by Miau
    Hi there So lets suppose we have an action in a controller that looks a bit like this: public ViewResult SomeAction(int id) { var data = _someService.GetData(id); ... //create new view model based on the data here return View(viewModel); } What I m trying to figure out is the best way to render a diferent view based on the type fo the data. the "_someService.GetData method returns an data that knows its out type (ie not only you can do typeof(data) but also you can do data.DataType and you ll get an enum value so I could achieve what I m trying to do doing something kinda like this public ViewResult SomeAction(int id) { var data = _someService.GetData(id); //I m mapping fields to the viewModel here var viewModel = GetViewModel(data); swtich(data.DataType) case DataType.TypeOne: return View("TypeOne", viewModel); break; ... } But this does not seem to be the nicest way, (I dont event know if it would work) Is this the way to go? Should I use some sort of RenderPartial Aproach? after all , waht will change in the view is mostly the order of the data (ie the rest of the view would be quite similar) Cheers

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  • C# casting question: from IEnumerable to custom type

    - by Sarah Vessels
    I have a custom class called Rows that implements IEnumerable<Row>. I often use LINQ queries on Rows instances: Rows rows = new Rows { row1, row2, row3 }; IEnumerable<Row> particularRows = rows.Where<Row>(row => condition); What I would like is to be able to do the following: Rows rows = new Rows { row1, row2, row3 }; Rows particularRows = (Rows)rows.Where<Row>(row => condition); However, I get a "System.InvalidCastException: Unable to cast object of type 'WhereEnumerableIterator1[NS.Row]' to type 'NS.Rows'". I do have a Rows constructor taking IEnumerable<Row>, so I could do: Rows rows = new Rows { row1, row2, row3 }; Rows particularRows = new Rows(rows.Where<Row>(row => condition)); This seems bulky, however, and I would love to be able to cast an IEnumerable<Row> to be a Rows since Rows implements IEnumerable<Row>. Any ideas?

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  • Cannot implicitly convert type ...

    - by Newbie
    I have the following function public Dictionary<DateTime, object> GetAttributeList( EnumFactorType attributeType ,Thomson.Financial.Vestek.Util.DateRange dateRange) { DateTime startDate = dateRange.StartDate; DateTime endDate = dateRange.EndDate; return (( //Step 1: Iterate over the attribute list and filter the records by // the supplied attribute type from assetAttribute in AttributeCollection where assetAttribute.AttributeType.Equals(attributeType) //Step2:Assign the TimeSeriesData collection into a temporary variable let timeSeriesList = assetAttribute.TimeSeriesData //Step 3: Iterate over the TimeSeriesData list and filter the records by // the supplied date from timeSeries in timeSeriesList.ToList() where timeSeries.Key >= startDate && timeSeries.Key <= endDate //Finally build the needed collection select new AssetAttribute() { TimeSeriesData = PopulateTimeSeriesData(timeSeries.Key, timeSeries.Value) }).ToList<AssetAttribute>().Select(i => i.TimeSeriesData)); } private Dictionary<DateTime, object> PopulateTimeSeriesData(DateTime dateTime, object value) { Dictionary<DateTime, object> timeSeriesData = new Dictionary<DateTime, object>(); timeSeriesData.Add(dateTime, value); return timeSeriesData; } Error:Cannot implicitly convert type 'System.Collections.Generic.IEnumerable' to 'System.Collections.Generic.Dictionary'. An explicit conversion exists (are you missing a cast?) Using C#3.0 Please help

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  • C# specifying generic delegate type param at runtime

    - by smerlin
    following setup, i have several generic functions, and i need to choose the type and the function identified by two strings at runtime. my first try looked like this: public static class FOOBAR { public delegate void MyDelegateType(int param); public static void foo<T>(int param){...} public static void bar<T>(int param){...} public static void someMethod(string methodstr, string typestr) { MyDelegateType mydel; Type mytype; switch(typestr) { case "int": mytype = typeof(int); break; case "double": mytype = typeof(double); break; default: throw new InvalidTypeException(typestr); } switch(methodstr) { case "foo": mydel = foo<mytype>; //error break; case "bar": mydel = bar<mytype>; //error break; default: throw new InvalidTypeException(methodstr); } for(int i=0; i<1000; ++i) mydel(i); } } since this didnt work, i nested those switchs (a methodstr switch inside the typestr switch or viceversa), but that solution is really ugly and unmaintainable. The number of types is pretty much fixed, but the number of functions like foo or bar will increase by high numbers, so i dont want nested switchs. So how can i make this working without using nested switchs ?

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  • Determining presence of prototype with correct return type

    - by R..
    Here's a random problem in C black magic I just came up with: Write a function that returns 1 if malloc has been prototyped to return a pointer type and 0 if malloc has a return type of int (either implicitly or due to wrong prototype), without invoking any implementation-defined or undefined behavior. I believe it's solvable, but I haven't worked out the solution. Note that calling the function cannot be necessary and in fact is not possible since calling a function with the incorrect prototype is undefined behavior. I have some ideas for ingredients but I think it makes for a better puzzle (and possibly more diverse ideas) if I leave them out for now. I don't need the solution for any immediate use, but it could be handy in configure scripts and such. Update: A better example of the usefulness (with strdup instead of malloc): #undef strdup #define strdup(x) (strdup_has_proto ? strdup((x)) : my_strdup((x))) i.e. being able to implement X_has_proto as an expression at the source level could be a portable way to use functions which a system might or might not have, and fall back on a local replacement, without needing any separate configure step.

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  • "error: Expected a type, got 'classname'" in C++

    - by Bay
    Using the following code: template <typename T> class node { [. . .] }; class b_graph { friend istream& operator>> (istream& in, b_graph& ingraph); friend ostream& operator<< (ostream& out, b_graph& outgraph); public: [...] private: vector<node> vertices; //This line I'm getting: error: type/value mismatch at argument 1 in template parameter list for ‘template<class _Tp, class _Alloc> class std::vector’ error: expected a type, got 'node' error: template argument 2 is invalid On the indicated line. Node is clearly defined before b_graph which uses it - what have I done here?

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  • Setting the type of a field in a superclass from a subclass (Java)

    - by Ibolit
    Hi. I am writing a project on Google App Engine, within it I have a number of abstract classes that I hope I will be able to use in my future projects, and a number of concrete classes inheriting from them. Among other abstract classes I have an abstract servlet that does user management, and I hava an abstract user. The AbstractUser has all the necessary fields and methods for storing it in the datastore and telling whether the user is registered with my service or not. It does not implement any project specific functionality. The abstract servlet that manages users, refers only to the methods declared in the AbstractUser class, which allows it to generate links for logging in, logging out and registering (for unregistered users). In order to implement the project-specific user functionality I need to subclass the Abstract user. The servlets I use in my project are all indirect descendants from that abstract user management servlet, and the user is a protected field in it, so the descendant servlets can use it as their own field. However, whenever i want to access any project specific method of the concrete user, i need to cast it to that type. i.e. (abstract user managing servlet) ... AbstractUser user = getUser(); ... abstract protected AbstractUser getUser(); (project-specific abstract servlet) @Override protected AbstractUser getUser() { return MyUserFactory.getUser(); } any other project specific servlet: int a = ((ConcreteUser) user).getA(); Well, what i'd like to do is to somehow make the type of “user” in the superclass depend on something in the project-specific abstract class. Is it at all possible? And i don't want to move all the user-management stuff into a project-specific layer, for i would like to have it for my future projects already written :) Thank you for your help.

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  • how to solve a weired swig python c++ interfacing type error

    - by user2981648
    I want to use swig to switch a simple cpp function to python and use "scipy.integrate.quadrature" function to calculate the integration. But python 2.7 reports a type error. Do you guys know what is going on here? Thanks a lot. Furthermore, "scipy.integrate.quad" runs smoothly. So is there something special for "scipy.integrate.quadrature" function? The code is in the following: File "testfunctions.h": #ifndef TESTFUNCTIONS_H #define TESTFUNCTIONS_H double test_square(double x); #endif File "testfunctions.cpp": #include "testfunctions.h" double test_square(double x) { return x * x; } File "swig_test.i" : /* File : swig_test.i */ %module swig_test %{ #include "testfunctions.h" %} /* Let's just grab the original header file here */ %include "testfunctions.h" File "test.py": import scipy.integrate import _swig_test print scipy.integrate.quadrature(_swig_test.test_square, 0., 1.) error info: UMD has deleted: _swig_test Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Python27\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 523, in runfile execfile(filename, namespace) File "D:\data\haitaliu\Desktop\Projects\swig_test\Release\test.py", line 4, in <module> print scipy.integrate.quadrature(_swig_test.test_square, 0., 1.) File "C:\Python27\lib\site-packages\scipy\integrate\quadrature.py", line 161, in quadrature newval = fixed_quad(vfunc, a, b, (), n)[0] File "C:\Python27\lib\site-packages\scipy\integrate\quadrature.py", line 61, in fixed_quad return (b-a)/2.0*sum(w*func(y,*args),0), None File "C:\Python27\lib\site-packages\scipy\integrate\quadrature.py", line 90, in vfunc return func(x, *args) TypeError: in method 'test_square', argument 1 of type 'double'

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  • What else I must do allow my method to handle any type of objects

    - by NewHelpNeeder
    So to allow any type object I must use generics in my code. I have rewrote this method to do so, but then when I create an object, for example Milk, it won't let me pass it to my method. Ether there's something wrong with my generic revision, or Milk object I created is not good. How should I pass my object correctly and add it to linked list? This is a method that causes error when I insert an item: public void insertFirst(T dd) // insert at front of list { Link newLink = new Link(dd); // make new link if( isEmpty() ) // if empty list, last = newLink; // newLink <-- last else first.previous = newLink; // newLink <-- old first newLink.next = first; // newLink --> old first first = newLink; // first --> newLink } This is my class I try to insert into linked list: class Milk { String brand; double size; double price; Milk(String a, double b, double c) { brand = a; size = b; price = c; } } This is test method to insert the data: public static void main(String[] args) { // make a new list DoublyLinkedList theList = new DoublyLinkedList(); // this causes: // The method insertFirst(Comparable) in the type DoublyLinkedList is not applicable for the arguments (Milk) theList.insertFirst(new Milk("brand", 1, 2)); // insert at front theList.displayForward(); // display list forward theList.displayBackward(); // display list backward } // end main() } // end class DoublyLinkedApp Declarations: class Link<T extends Comparable<T>> {} class DoublyLinkedList<T extends Comparable<T>> {}

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  • Cast exception being generated when using the same type of object

    - by David Tunnell
    I was previously using static variables to hold variable data that I want to save between postbacks. I was having problems and found that the data in these variables is lost when the appdomain ends. So I did some research and decided to go with ViewStates: static Dictionary<string, linkButtonObject> linkButtonDictonary; protected void Page_Load(object sender, EventArgs e) { if (ViewState["linkButtonDictonary"] != null) { linkButtonDictonary = (Dictionary<string, linkButtonObject>)ViewState["linkButtonDictonary"]; } else { linkButtonDictonary = new Dictionary<string, linkButtonObject>(); } } And here is the very simple class I use: [Serializable] public class linkButtonObject { public string storyNumber { get; set; } public string TaskName { get; set; } } I am adding to linkButtonDictionary as a gridview is databound: protected void hoursReportGridView_OnRowDataBound(Object sender, GridViewRowEventArgs e) { if (e.Row.RowType == DataControlRowType.DataRow) { LinkButton btn = (LinkButton)e.Row.FindControl("taskLinkButton"); linkButtonObject currentRow = new linkButtonObject(); currentRow.storyNumber = e.Row.Cells[3].Text; currentRow.TaskName = e.Row.Cells[5].Text; linkButtonDictonary.Add(btn.UniqueID, currentRow); } } It appears that my previous issues are resolved however a new one has arisin. Sometime when I postback I am getting this error: [A]System.Collections.Generic.Dictionary2[System.String,linkButtonObject] cannot be cast to [B]System.Collections.Generic.Dictionary2[System.String,linkButtonObject]. Type A originates from 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' in the context 'LoadNeither' at location 'C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. Type B originates from 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' in the context 'LoadNeither' at location 'C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. I don't understand how there can be a casting issue when I am using the same class everywhere. What am I doing wrong and how do I fix it?

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  • Python list recursion type error

    - by Jacob J Callahan
    I can't seem to figure out why the following code is giving me a TypeError: 'type' object is not iterable pastebin: http://pastebin.com/VFZYY4v0 def genList(self): #recursively generates a sorted list of child node values numList = [] if self.leftChild != 'none': numList.extend(self.leftChild.genList()) #error numList.extend(list((self.Value,))) if self.rightChild != 'none': numList.extend(self.rightChild.genList()) #error return numList code that adds child nodes (works correctly) def addChild(self, child): #add a child node. working if child.Value < self.Value: if self.leftChild == 'none': self.leftChild = child child.parent = self else: self.leftChild.addChild(child) elif child.Value > self.Value: if self.rightChild == 'none': self.rightChild = child child.parent = self else: self.rightChild.addChild(child) Any help would be appreciated. Full interpreter session: >>> import BinTreeNode as BTN >>> node1 = BTN.BinaryTreeNode(5) >>> node2 = BTN.BinaryTreeNode(2) >>> node3 = BTN.BinaryTreeNode(12) >>> node3 = BTN.BinaryTreeNode(16) >>> node4 = BTN.BinaryTreeNode(4) >>> node5 = BTN.BinaryTreeNode(13) >>> node1.addChild(node2) >>> node1.addChild(node3) >>> node1.addChild(node4) >>> node1.addChild(node5) >>> node4.genList() <class 'list'> >>> node1.genList() Traceback (most recent call last): File "<interactive input>", line 1, in <module> File "C:...\python\BinTreeNode.py", line 47, in genList numList.extend(self.leftChild.genList()) #error File "C:...\python\BinTreeNode.py", line 52, in genList TypeError: 'type' object is not iterable

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  • Storing C++ templated objects as same type

    - by JaredC
    I have a class that is a core component of a performance sensitive code path, so I am trying to optimize it as much as possible. The class used to be: class Widget { Widget(int n) : N(n) {} .... member functions that use the constant value N .... const int N; // just initialized, will never change } The arguments to the constructor are known at compile time, so I have changed this class to a template, so that N can be compiled into the functions: template<int N> class Widget { .... member functions that use N .... } I have another class with a method: Widget & GetWidget(int index); However, after templating Widget, each widget has a different type so I cannot define the function like this anymore. I considered different inheritance options, but I'm not sure that the performance gain from the template would outweigh the cost of inherited function invocations. SO, my question is this: I am pretty sure I want the best of both worlds (compile-time / run-time), and it may not be possible. But, is there a way to gain the performance of knowing N at compile time, but still being able to return Widgets as the same type? Thanks!

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