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  • Good practice to create extension methods that apply to System.Object?

    - by Christian
    Hello, I'm wondering whether I should create extension methods that apply on the object level or whether they should be located at a lower point in the class hierarchy. What I mean is something along the lines of: public static string SafeToString(this Object o) { if (o == null || o is System.DBNull) return ""; else { if (o is string) return (string)o; else return ""; } } public static int SafeToInt(this Object o) { if (o == null || o is System.DBNull) return 0; else { if (o.IsNumeric()) return Convert.ToInt32(o); else return 0; } } //same for double.. etc I wrote those methods since I have to deal a lot with database data (From the OleDbDataReader) that can be null (shouldn't, though) since the underlying database is unfortunately very liberal with columns that may be null. And to make my life a little easier, I came up with those extension methods. What I'd like to know is whether this is good style, acceptable style or bad style. I kinda have my worries about it since it kinda "pollutes" the Object-class. Thank you in advance & Best Regards :) Christian P.S. I didn't tag it as "subjective" intentionally.

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  • C# - Cannot implicitly convert type List<Product> to List<IProduct>

    - by Keith Barrows
    I have a project with all my Interface definitions: RivWorks.Interfaces I have a project where I define concrete implmentations: RivWorks.DTO I've done this hundreds of times before but for some reason I am getting this error now: Cannot implicitly convert type 'System.Collections.Generic.List<RivWorks.DTO.Product>' to 'System.Collections.Generic.List<RivWorks.Interfaces.DataContracts.IProduct>' Interface definition (shortened): namespace RivWorks.Interfaces.DataContracts { public interface IProduct { [XmlElement] [DataMember(Name = "ID", Order = 0)] Guid ProductID { get; set; } [XmlElement] [DataMember(Name = "altID", Order = 1)] long alternateProductID { get; set; } [XmlElement] [DataMember(Name = "CompanyId", Order = 2)] Guid CompanyId { get; set; } ... } } Concrete class definition (shortened): namespace RivWorks.DTO { [DataContract(Name = "Product", Namespace = "http://rivworks.com/DataContracts/2009/01/15")] public class Product : IProduct { #region Constructors public Product() { } public Product(Guid ProductID) { Initialize(ProductID); } public Product(string SKU, Guid CompanyID) { using (RivEntities _dbRiv = new RivWorksStore(stores.RivConnString).NegotiationEntities()) { model.Product rivProduct = _dbRiv.Product.Where(a => a.SKU == SKU && a.Company.CompanyId == CompanyID).FirstOrDefault(); if (rivProduct != null) Initialize(rivProduct.ProductId); } } #endregion #region Private Methods private void Initialize(Guid ProductID) { using (RivEntities _dbRiv = new RivWorksStore(stores.RivConnString).NegotiationEntities()) { var localProduct = _dbRiv.Product.Include("Company").Where(a => a.ProductId == ProductID).FirstOrDefault(); if (localProduct != null) { var companyDetails = _dbRiv.vwCompanyDetails.Where(a => a.CompanyId == localProduct.Company.CompanyId).FirstOrDefault(); if (companyDetails != null) { if (localProduct.alternateProductID != null && localProduct.alternateProductID > 0) { using (FeedsEntities _dbFeed = new FeedStoreReadOnly(stores.FeedConnString).ReadOnlyEntities()) { var feedProduct = _dbFeed.AutoWithImage.Where(a => a.ClientID == companyDetails.ClientID && a.AutoID == localProduct.alternateProductID).FirstOrDefault(); if (companyDetails.useZeroGspPath.Value || feedProduct.GuaranteedSalePrice > 0) // kab: 2010.04.07 - new rules... PopulateProduct(feedProduct, localProduct, companyDetails); } } else { if (companyDetails.useZeroGspPath.Value || localProduct.LowestPrice > 0) // kab: 2010.04.07 - new rules... PopulateProduct(localProduct, companyDetails); } } } } } private void PopulateProduct(RivWorks.Model.Entities.Product product, RivWorks.Model.Entities.vwCompanyDetails RivCompany) { this.ProductID = product.ProductId; if (product.alternateProductID != null) this.alternateProductID = product.alternateProductID.Value; this.BackgroundColor = product.BackgroundColor; ... } private void PopulateProduct(RivWorks.Model.Entities.AutoWithImage feedProduct, RivWorks.Model.Entities.Product rivProduct, RivWorks.Model.Entities.vwCompanyDetails RivCompany) { this.alternateProductID = feedProduct.AutoID; this.BackgroundColor = Helpers.Product.GetCorrectValue(RivCompany.defaultBackgroundColor, rivProduct.BackgroundColor); ... } #endregion #region IProduct Members public Guid ProductID { get; set; } public long alternateProductID { get; set; } public Guid CompanyId { get; set; } ... #endregion } } In another class I have: using dto = RivWorks.DTO; using contracts = RivWorks.Interfaces.DataContracts; ... public static List<contracts.IProduct> Get(Guid companyID) { List<contracts.IProduct> myList = new List<dto.Product>(); ... Any ideas why this might be happening? (And I am sure it is something trivially simple!)

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  • How to manipulate *huge* amounts of data

    - by Alejandro
    Hi there! I'm having the following problem. I need to store huge amounts of information (~32 GB) and be able to manipulate it as fast as possible. I'm wondering what's the best way to do it (combinations of programming language + OS + whatever you think its important). The structure of the information I'm using is a 4D array (NxNxNxN) of double-precission floats (8 bytes). Right now my solution is to slice the 4D array into 2D arrays and store them in separate files in the HDD of my computer. This is really slow and the manipulation of the data is unbearable, so this is no solution at all! I'm thinking on moving into a Supercomputing facility in my country and store all the information in the RAM, but I'm not sure how to implement an application to take advantage of it (I'm not a professional programmer, so any book/reference will help me a lot). An alternative solution I'm thinking on is to buy a dedicated server with lots of RAM, but I don't know for sure if that will solve the problem. So right now my ignorance doesn't let me choose the best way to proceed. What would you do if you were in this situation? I'm open to any idea. Thanks in advance!

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  • Fastest way to convert a list of doubles to a unique list of integers?

    - by javanix
    I am dealing with a MySQL table here that is keyed in a somewhat unfortunate way. Instead of using an auto increment table as a key, it uses a column of decimals to preserve order (presumably so its not too difficult to insert new rows while preserving a primary key and order). Before I go through and redo this table to something more sane, I need to figure out how to rekey it without breaking everything. What I would like to do is something that takes a list of doubles (the current keys) and outputs a list of integers (which can be cast down to doubles for rekeying). For example, input {1.00, 2.00, 2.50, 2.60, 3.00} would give output {1, 2, 3, 4, 5). Since this is a database, I also need to be able to update the rows nicely: UPDATE table SET `key`='3.00' WHERE `key`='2.50'; Can anyone think of a speedy algorithm to do this? My current thought is to read all of the doubles into a vector, take the size of the vector, and output a new vector with values from 1 => doubleVector.size. This seems pretty slow, since you wouldn't want to read every value into the vector if, for instance, only the last n/100 elements needed to be modified. I think there is probably something I can do in place, since only values after the first non-integer double need to be modified, but I can't for the life of me figure anything out that would let me update in place as well. For instance, setting 2.60 to 3.00 the first time you see 2.50 in the original key list would result in an error, since the key value 3.00 is already used for the table.

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  • How to compare two variables from a java class in jess and execute a rule?

    - by user3417084
    I'm beginner in Jess. I'm trying to compare two variables from a Java class in Jess and trying to execute a rule. I have imported cTNumber and measuredCurrent (both are integer)form a java class called CurrentSignal. Similarly imported vTNumberand measuredVoltage form a java class DERSignal. Now I want to make a rule such that if cTNumber is equal to vTNumber then multiply measuredCurrent and measuredVoltage (Both are double) for calculating power. I'm trying in this way.... (import signals.*) (deftemplate CurrentSignal (declare (from-class CurrentSignal))) (deftemplate DERSignal (declare (from-class DERSignal))) (defglobal ?*CTnumber* = 0) (defglobal ?*VTnumber* = 0) (defglobal ?*VTnumberDER* = 0) (defglobal ?*measuredCurrent* = 0) (defglobal ?*measuredVoltage* = 0) (defglobal ?*measuredVoltageDER* = 0) (defrule Get-CT-Number (CurrentSignal (cTNumber ?m)) (CurrentSignal (measuredCurrent ?c)) => (bind ?*measuredCurrent* ?c) (printout t "Measured Current : " ?*measuredCurrent*" Amps"crlf) (bind ?*CTnumber* ?m) (printout t ?*CTnumber* crlf) ) (defrule Get-DER-Number (DERSignal (vTNumber ?o)) (DERSignal (measuredVoltage ?V)) => (bind ?*measuredVoltageDER* ?V) (printout t "Measured Voltage : " ?*measuredVoltageDER* " V" crlf) (bind ?*VTnumberDER* ?o) (printout t ?*VTnumberDER* crlf) ) (defrule Power-Calculation-DER-signal "Power calculation of DER Bay" (test (= ?*CTnumber* ?*VTnumberDER* )) => (printout t "Total Generation : " (* ?*measuredCurrent* ?*measuredVoltageDER*) crlf) ) But the Total Generation is showing 0. But I tried calculating in Java and it's showing a number. Can anyone please help me to solve this problem. Thank you.

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  • Customers angry, fighting unknown DLL dependencies

    - by wheaties
    I'm a one man show developing a C++ Windows application for a customer. Over the past several months we've been running to the same problems with missing DLL dependencies on customer machines. Despite my best efforts something keeps going wrong and we get angry emails back. My boss and my boss's boss are angry with me and the customers aren't happy. I'm hoping you guys can help out and give suggestions/ideas on how to get the deliverables in order. Before some of the obvious: I have no test machine. That is, I can't replicate the customer environment nor attempt to install the app on a "clean" system to catch gotchas before shipping. I've tried using depends.exe to track down what versions of the DLLs my project is dependent upon. I'm shipping our code with the redistributables I've been able to find that way. After that it's an angry customer email waiting game. I'm required to use a third-party DLL which can not be registered (it's buggy as hell.) I'm not supposed to use Install Shield, any other automated installer, or write an install script. I provide written instructions on how to get the app installed (unzip, double click exe file.) I'm tired of taking heat for this stuff. What am I missing that I could be doing? What should I ask in terms of support from my employer? How should I ask for that support in a way that they'll provide it?

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  • wxGraphicsContext dreadfully slow on Windows

    - by Jonatan
    I've implemented a plotter using wxGraphicsContext. The development was done using wxGTK, and the graphics was very fast. Then I switched to Windows (XP) using wxWidgets 2.9.0. And the same code is extremely slow. It takes about 350 ms to render a frame. Since the user is able to drag the plotter with the mouse to navigate it feels very sluggish with such a slow update rate. I've tried to implement some parts using wxDC and benchmarked the difference. With wxDC the code runs just about 100 times faster. As far as I know both Cairo and GDI+ are implemented in software at this point, so there's no real reason Cairo should be so much faster than GDI+. Am I doing something wrong? Or is the GDI+ implementation just not up on par with Cairo? One small note: I'm rendering to a wxBitmap now, with the wxGraphicsContext created from a wxMemoryDC. This is to avoid flicker on XP, since double buffering doesn't work there.

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  • Large flags enumerations in C#

    - by LorenVS
    Hey everyone, got a quick question that I can't seem to find anything about... I'm working on a project that requires flag enumerations with a large number of flags (up to 40-ish), and I don't really feel like typing in the exact mask for each enumeration value: public enum MyEnumeration : ulong { Flag1 = 1, Flag2 = 2, Flag3 = 4, Flag4 = 8, Flag5 = 16, // ... Flag16 = 65536, Flag17 = 65536 * 2, Flag18 = 65536 * 4, Flag19 = 65536 * 8, // ... Flag32 = 65536 * 65536, Flag33 = 65536 * 65536 * 2 // right about here I start to get really pissed off } Moreover, I'm also hoping that there is an easy(ier) way for me to control the actual arrangement of bits on different endian machines, since these values will eventually be serialized over a network: public enum MyEnumeration : uint { Flag1 = 1, // BIG: 0x00000001, LITTLE:0x01000000 Flag2 = 2, // BIG: 0x00000002, LITTLE:0x02000000 Flag3 = 4, // BIG: 0x00000004, LITTLE:0x03000000 // ... Flag9 = 256, // BIG: 0x00000010, LITTLE:0x10000000 Flag10 = 512, // BIG: 0x00000011, LITTLE:0x11000000 Flag11 = 1024 // BIG: 0x00000012, LITTLE:0x12000000 } So, I'm kind of wondering if there is some cool way I can set my enumerations up like: public enum MyEnumeration : uint { Flag1 = flag(1), // BOTH: 0x80000000 Flag2 = flag(2), // BOTH: 0x40000000 Flag3 = flag(3), // BOTH: 0x20000000 // ... Flag9 = flag(9), // BOTH: 0x00800000 } What I've Tried: // this won't work because Math.Pow returns double // and because C# requires constants for enum values public enum MyEnumeration : uint { Flag1 = Math.Pow(2, 0), Flag2 = Math.Pow(2, 1) } // this won't work because C# requires constants for enum values public enum MyEnumeration : uint { Flag1 = Masks.MyCustomerBitmaskGeneratingFunction(0) } // this is my best solution so far, but is definitely // quite clunkie public struct EnumWrapper<TEnum> where TEnum { private BitVector32 vector; public bool this[TEnum index] { // returns whether the index-th bit is set in vector } // all sorts of overriding using TEnum as args } Just wondering if anyone has any cool ideas, thanks!

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  • Styling definition lists - IE clear:both bug

    - by Andrea
    Hi guys, I'm trying to style a definition list properly. So far I've got the style that I wanted in Firefox 3.5 and IE 8 but I couldn't get IE6 and IE7 to behave properly... I've already tried any kind of hack and trickery I could possibly think of. It seems like the "clear:both" on the dt doesn't work in IE<=7... Below is the "test page" that I'm using. The markup of the definition list is built on purpose: I wanna test different scenarios such as multiple definitions or empty one. Check it in Firefox 3.5 to see how it should look like. Cheers!!! <!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> <title></title> <style type="text/css"> body { font-family: Arial; font-size: 62.5%; } * { margin: 0; padding: 0; } #main { font-size: 1.4em; } dt { font-weight: bold; } hr { clear: both; } dl.aligned { width: 300px; } .aligned dt { clear: both; float: left; margin: 0 0 0.5em 0; width: 100px; } .aligned dd { clear: right; float: right; margin: 0 0 0.5em 10px; width: 190px; } </style> </head> <body> <div id="main"> <dl class="aligned"> <dt>First title</dt> <dd>1.1 definition</dd> <dd>1.2 definition - very long to test wrapping</dd> <dd>1.3 definition</dd> <dt>Second title</dt> <dd></dd> <dd></dd> <dt>Third title</dt> <dd>3.0 definition</dd> <dt>Fourth title - very long to test wrapping</dt> <dt>Fifth title</dt> <dt>Sixth title</dt> <dd>6.0 definition</dd> </dl> </div> </body> </html>

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  • Getting around IBActions limited scope

    - by Septih
    Hello, I have an NSCollectionView and the view is an NSBox with a label and an NSButton. I want a double click or a click of the NSButton to tell the controller to perform an action with the represented object of the NSCollectionViewItem. The Item View is has been subclassed, the code is as follows: #import <Cocoa/Cocoa.h> #import "WizardItem.h" @interface WizardItemView : NSBox { id delegate; IBOutlet NSCollectionViewItem * viewItem; WizardItem * wizardItem; } @property(readwrite,retain) WizardItem * wizardItem; @property(readwrite,retain) id delegate; -(IBAction)start:(id)sender; @end #import "WizardItemView.h" @implementation WizardItemView @synthesize wizardItem, delegate; -(void)awakeFromNib { [self bind:@"wizardItem" toObject:viewItem withKeyPath:@"representedObject" options:nil]; } -(void)mouseDown:(NSEvent *)event { [super mouseDown:event]; if([event clickCount] > 1) { [delegate performAction:[wizardItem action]]; } } -(IBAction)start:(id)sender { [delegate performAction:[wizardItem action]]; } @end The problem I've run into is that as an IBAction, the only things in the scope of -start are the things that have been bound in IB, so delegate and viewItem. This means that I cannot get at the represented object to send it to the delegate. Is there a way around this limited scope or a better way or getting hold of the represented object? Thanks.

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  • Decoupling the view, presentation and ASP.NET Web Forms

    - by John Leidegren
    I have an ASP.NET Web Forms page which the presenter needs to populate with controls. This interaction is somewhat sensitive to the page-life cycle and I was wondering if there's a trick to it, that I don't know about. I wanna be practical about the whole thing but not compromise testability. Currently I have this: public interface ISomeContract { void InstantiateIn(System.Web.UI.Control container); } This contract has a dependency on System.Web.UI.Control and I need that to be able to do things with the ASP.NET Web Forms programming model. But neither the view nor the presenter may have knowledge about ASP.NET server controls. How do I get around this? How can I work with the ASP.NET Web Forms programming model in my concrete views without taking a System.Web.UI.Control dependency in my contract assemblies? To clarify things a bit, this type of interface is all about UI composition (using MEF). It's known through-out the framework but it's really only called from within the concrete view. The concrete view is still the only thing that knows about ASP.NET Web Forms. However those public methods that say InstantiateIn(System.Web.UI.Control) exists in my contract assemblies and that implies a dependency on ASP.NET Web Forms. I've been thinking about some double dispatch mechanism or even visitor pattern to try and work around this.

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  • What is the cleanest way to use anonymous functions?

    - by Fletcher Moore
    I've started to use Javascript a lot more, and as a result I am writing things complex enough that organization is becoming a concern. However, this question applies to any language that allows you to nest functions. Essentially, when should you use an anonymous function over a named global or inner function? At first I thought it was the coolest feature ever, but I think I am going overboard. Here's an example I wrote recently, ommiting all the variable delcarations and conditionals so that you can see the structure. function printStream() { return fold(function (elem, acc) { ... var comments = (function () { return fold(function (comment, out) { ... return out + ...; }, '', elem.comments); return acc + ... + comments; }, '', data.stream); } I realized though (I think) there's some kind of beauty in being so compact, it is probably isn't a good idea to do this in the same way you wouldn't want a ton of code in a double for loop.

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  • Parameter cannot be null error after success save

    - by tigermain
    I am getting the following nhibernate error when saving an entity (via: NHibernateSession.Save(entity);) despite it being persisted to the database fine "Value cannot be null.\r\nParameter name: id" This is my hbm file <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="JeanieMaster.Domain.Entities" assembly="JeanieMaster.Domain"> <class name="ActionLog" table="ActionLog" schema="[DBSVR1].[mydatabase].[dbo]" select-before-update="false" optimistic-lock="none"> <id name="Id" column="ActionLogId" type="Int32"> <generator class="identity"/> </id> <property name="ActionId" type="Int32"/> <many-to-one name="User" class="JeanieUser" column="UserId" /> <many-to-one name="ApplicationProvider" class="ApplicationProvider" column="ApplicationProviderId" /> <many-to-one name="ContentProvider" class="ContentProvider" column="ContentProviderId" /> <many-to-one name="SearchLog" class="SearchLog" column="SearchLogId" /> <property name="Data" type="string"/> <property name="DateCreated" type="DateTime"/> <property name="ActionDuration" type="Double"/> </class> </hibernate-mapping>

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  • How to use boost normal distribution classes?

    - by David Alfonso
    Hi all, I'm trying to use boost::normal_distribution in order to generate a normal distribution with mean 0 and sigma 1. The following code uses boost normal classes. Am I using them correctly? #include <boost/random.hpp> #include <boost/random/normal_distribution.hpp> int main() { boost::mt19937 rng; // I don't seed it on purpouse (it's not relevant) boost::normal_distribution<> nd(0.0, 1.0); boost::variate_generator<boost::mt19937&, boost::normal_distribution<> > var_nor(rng, nd); int i = 0; for (; i < 10; ++i) { double d = var_nor(); std::cout << d << std::endl; } } The result on my machine is: 0.213436 -0.49558 1.57538 -1.0592 1.83927 1.88577 0.604675 -0.365983 -0.578264 -0.634376 As you can see all values are not between -1 and 1. Thank you all in advance!

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  • Change the playback rate of a track in real time on Android

    - by android_dev
    Hello, I would like to know if somebody knows a library to changing the playback rate of a track in real time. My idea is to load a track and change its playback rate to half or double. Firstly, I tried with MusicPlayer but is was not possible at all and then I tried with SoundPool. The problem is that with SoundPool I can´t change the rate once the track is loaded. Here is the code I am using (proof of concept): float j = 1; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button b = (Button)findViewById(R.id.Button01); b.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { j = (float) (j +.5); } }); AssetFileDescriptor afd; try { SoundPool sp = new SoundPool(1, AudioManager.STREAM_MUSIC, 0); afd = getAssets().openFd("wav/sample.wav"); int id = sp.load(afd, 1); sp.play(id, 1, 1, 1, 0, j); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } When I press the button, the playback rate should increase but it does not happen. Any idea of how change the rate in real time? Thanks in advance.

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  • Future of VB.NET? [closed]

    - by Alex Yeung
    Hi all, I worked with C# for years. Last year, I changed my job and the company use VB.NET. Of course, theoretically C# and VB.NET are very similar and I easily adapted. However, I have worked for VB.NET for 1 year. I cannot see any future of VB.NET. As a programming language, it is so foo. Here is a list of what C# can do but VB.NET cannot Case insensitive variables how to think a new variable name? If I have a property called FolderPath, i need to establish another private variable called _folderPath or m_folderPath. In C#, FolderPath and folderPath are two variables. Moreover, it gets compile error if variable name is same as a class name. For example Dim guid = Guid.NewGuid(). (What the...) Again, I need to think a new variable name. Adhoc scope In C#, we could use {...} to create a adhoc scope and all resource in {...} will not affect the code outside. However there is not such syntax in VB.NET. I could only use If True Then and End If to make a local scope which is so unclear. In-Method Region Sometime, it is unavoidable to have a long long method. VB.NET does not support in-method region. I always need to scroll down for 1000 lines. It wastes my time. No multi-line string definition In C#, we could var s = @"..." to define a multi-line string. In VB.NET there is no direct method to do that. The indirect way is use XML-literal string. Dim s = <![CDATA[...]]>.Value. However it is unclear. No block comment In C#, we have line comment // and block comment /* ... */. However in VB.NET we only have line comment which is a very big trouble for me. No statement end symbol Statements are separated by line break in VB.NET; while statements are separated by ; in C#. Underscore I think many people know underscore _ is continue statement symbol. I really disagree with that. I know MS VB.NET language team is going to remove the underscore syntax from VB.NET. However what can we do now? Although underscore is removed in the future, what's the advantage of that? I cannot see any advantage! With scope With scope is an evil scope. Although it allows shorter statement, it is hard to trace. Default Namesapce in project level It is a nightmare for me. The only advantage of VB.NET is property initialization. I think C# cannot do that (correct me if I am wrong.) Public Property ThisIsMyProperty As String = "MyValue" Remarks: I don't think optional method parameters is an advantage of OOP. By those disadvantages, I cannot see the future of VB.NET. Anyone sees the future of VB.NET?

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  • template style matrix implementation in c

    - by monkeyking
    From time to time I use the following code for generating a matrix style datastructure typedef double myType; typedef struct matrix_t{ |Compilation started at Mon Apr 5 02:24:15 myType **matrix; | size_t x; |gcc structreaderGeneral.c -std=gnu99 -lz size_t y; | }matrix; |Compilation finished at Mon Apr 5 02:24:15 | | matrix alloc_matrix(size_t x, size_t y){ | if(0) | fprintf(stderr,"\t-> Alloc matrix with dim (%lu,%lu) byteprline=%lu bytetotal:%l\| u\n",x,y,y*sizeof(myType),x*y*sizeof(myType)); | | myType **m = (myType **)malloc(x*sizeof(myType **)); | for(size_t i=0;i<x;i++) | m[i] =(myType *) malloc(y*sizeof(myType *)); | | matrix ret; | ret.x=x; | ret.y=y; | ret.matrix=m; | return ret; | } And then I would change my typedef accordingly if I needed a different kind of type for the entries in my matrix. Now I need 2 matrices with different types, an easy solution would be to copy/paste the code, but is there some way to do a template styled implementation. Thanks

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  • Problem with relative file path

    - by Richard Knop
    So here is my program, which works ok: import java.io.FileReader; import java.io.BufferedReader; import java.io.IOException; import java.util.Scanner; import java.util.Locale; public class ScanSum { public static void main(String[] args) throws IOException { Scanner s = null; double sum = 0; try { s = new Scanner(new BufferedReader(new FileReader("D:/java-projects/HelloWorld/bin/usnumbers.txt"))); s.useLocale(Locale.US); while (s.hasNext()) { if (s.hasNextDouble()) { sum += s.nextDouble(); } else { s.next(); } } } finally { s.close(); } System.out.println(sum); } } As you can see, I am using absolute path to the file I am reading from: s = new Scanner(new BufferedReader(new FileReader("D:/java-projects/HelloWorld/bin/usnumbers.txt"))); The problem arises when I try to use the relative path: s = new Scanner(new BufferedReader(new FileReader("usnumbers.txt"))); I get an error: Exception in thread "main" java.lang.NullPointerException at ScanSum.main(ScanSum.java:24) The file usnumbers.txt is in the same directory as the ScanSum.class file: D:/java-projects/HelloWorld/bin/ScanSum.class D:/java-projects/HelloWorld/bin/usnumbers.txt How could I solve this?

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  • Box2dx: Cancel force on a body?

    - by Rosarch
    I'm doing pathfinding where I use force to push body to waypoints. However, once they get close enough to the waypoint, I want to cancel out the force. How can I do this? Do I need to maintain separately all the forces I've applied to the body in question? I'm using Box2dx (C#/XNA). Here is my attempt, but it doesn't work at all: internal PathProgressionStatus MoveAlongPath(PositionUpdater posUpdater) { Vector2 nextGoal = posUpdater.Goals.Peek(); Vector2 currPos = posUpdater.Model.Body.Position; float distanceToNextGoal = Vector2.Distance(currPos, nextGoal); bool isAtGoal = distanceToNextGoal < PROXIMITY_THRESHOLD; Vector2 forceToApply = new Vector2(); double angleToGoal = Math.Atan2(nextGoal.Y - currPos.Y, nextGoal.X - currPos.X); forceToApply.X = (float)Math.Cos(angleToGoal) * posUpdater.Speed; forceToApply.Y = (float)Math.Sin(angleToGoal) * posUpdater.Speed; float rotation = (float)(angleToGoal + Math.PI / 2); posUpdater.Model.Body.Rotation = rotation; if (!isAtGoal) { posUpdater.Model.Body.ApplyForce(forceToApply, posUpdater.Model.Body.Position); posUpdater.forcedTowardsGoal = true; } if (isAtGoal) { // how can the body be stopped? posUpdater.forcedTowardsGoal = false; //posUpdater.Model.Body.SetLinearVelocity(new Vector2(0, 0)); //posUpdater.Model.Body.ApplyForce(-forceToApply, posUpdater.Model.Body.GetPosition()); posUpdater.Goals.Dequeue(); if (posUpdater.Goals.Count == 0) { return PathProgressionStatus.COMPLETE; } } UPDATE If I do keep track of how much force I've applied, it fails to account for other forces that may act on it. I could use reflection and set _force to zero directly, but that feels dirty.

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  • QGraphicsView and custom Cursors

    - by Etienne de Martel
    I am trying to make use of a mix of custom cursors and preset cursors for my QGraphicsView. In my implementation we have created a notion of "modes" for the view. Meaning that depending on what "mode" the user is in, different things will happen on the left-click, or left-click drag. Anyway, none of that is the problem, just the context. The problem arises when I try to change the cursor for each mode. For instance, for mode 1 we want to show the regular Arrow cursor, but for mode 2, we want to use a custom pixmap. Seemingly simple we call graphicsview->viewport()->setCursor(Qt::QArrowCursor)  when we are switching to mode 1, and graphicsview->viewport()->setCursor(our custom cursor) for mode 2. Except it doesn't work at all. Firstly, the cursor does not change to the custom cursor. That is the first problem. However, if through another operation the drag mode of the graphics view gets set to ScrollHandDrag, the cursor will switch to the custom cursor once the drag operation is complete. Weird. But the plot thickens... Once we switch to the custom cursor, it can never be changed back to the ArrorCursor no matter how many times we call setCursor(Qt::QArrowCursor). it also doesn't seem to matter whether I call setCursor on the viewport or the graphics view itself. So, just for fun, I added a call to graphicsview->unsetCursor() just before we want to change the cursor, and that at least rectifies the second problem. The cursor changes just fine so long as we do a little HandDragging in between. Better, but certainly not optimal. However it should be noted, that doing the unsetCursor on the viewport doesn't work. it must absolutely be done on the graphicsview - regardless of the fact that we are setting the cursor on the viewport. To completely patch over the problem I have added these two lines after I set the cursor: graphicsview->setDragMode(QGraphicsView::ScrollHandDrag); graphicsview->setDragMode(QGraphicsView::NoDrag); Which works, but ye gads!! So something magical is happening inside these two methods that fixes the problem, but glancing at the code I don't see what. Something to do with the fact that the drag mode is changing the cursor I imagine. Just for completeness, I should also mention that the thing that triggers the mode change, is a QPushButton that has been added to the scene using QGraphicsScene->addWidget(). I don't know if that has anything to do with it, but you never know. I am hoping that either someone could clarify why I need to make these seemingly random calls. I don't think I am doing anything wrong anywhere. Thanks in advance for any help. EDIT: Here is an actual code example with the cursor patches as described above. You can look at and/or download them from the link below. It was a little long to paste here. I included the framework around which the cursors are changed, because I have a funny feeling that that is important somehow. https://gist.github.com/712654 The code where the problem lies is in MyGraphicsView.cpp starting at line 104. This is where the cursor is set in the graphics view. It is exactly as described above. Keep in mind, with the very ugly patches in place the cursors do work - more or less. Without those lines you will see very clearly the problems listed in the post above. Also included in the link, is all the code for a mainWindow that uses the view, etc... the only thing missing are the images I am using. But the images themselves don't matter, any 16x16 pngs will do.

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  • Left/Right/Inner joins using C# and LINQ

    - by Keith Barrows
    I am trying to figure out how to do a series of queries to get the updates, deletes and inserts segregated into their own calls. I have 2 tables, one in each of 2 databases. One is a Read Only feeds database and the other is the T-SQL R/W Production source. There are a few key columns in common between the two. What I am doing to setup is this: List<model.AutoWithImage> feedProductList = _dbFeed.AutoWithImage.Where(a => a.ClientID == ClientID).ToList(); List<model.vwCompanyDetails> companyDetailList = _dbRiv.vwCompanyDetails.Where(a => a.ClientID == ClientID).ToList(); foreach (model.vwCompanyDetails companyDetail in companyDetailList) { List<model.Product> productList = _dbRiv.Product.Include("Company").Where(a => a.Company.CompanyId == companyDetail.CompanyId).ToList(); } Now that I have a (source) list of products from the feed, and an existing (target) list of products from my prod DB I'd like to do 3 things: Find all SKUs in the feed that are not in the target Find all SKUs that are in both, that are active feed products and update the target Find all SKUs that are in both, that are inactive and soft delete from the target What are the best practices for doing this without running a double loop? Would prefer a LINQ 4 Objects solution as I already have my objects. EDIT: BTW, I will need to transfer info from feed rows to target rows in the first 2 instances, just set a flag in the last instance. TIA

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  • An Ideal Keyboard Layout for Programming

    - by Jon Purdy
    I often hear complaints that programming languages that make heavy use of symbols for brevity, most notably C and C++ (I'm not going to touch APL), are difficult to type because they require frequent use of the shift key. A year or two ago, I got tired of it myself, downloaded Microsoft's Keyboard Layout Creator, made a few changes to my layout, and have not once looked back. The speed difference is astounding; with these few simple changes I am able to type C++ code around 30% faster, depending of course on how hairy it is; best of all, my typing speed in ordinary running text is not compromised. My questions are these: what alternate keyboard layouts have existed for programming, which have gained popularity, are any of them still in modern use, do you personally use any altered layout, and how can my layout be further optimised? I made the following changes to a standard QWERTY layout. (I don't use Dvorak, but there is a programmer Dvorak layout worth mentioning.) Swap numbers with symbols in the top row, because long or repeated literal numbers are typically replaced with named constants; Swap backquote with tilde, because backquotes are rare in many languages but destructors are common in C++; Swap minus with underscore, because underscores are common in identifiers; Swap curly braces with square brackets, because blocks are more common than subscripts; and Swap double quote with single quote, because strings are more common than character literals. I suspect this last is probably going to be the most controversial, as it interferes the most with running text by requiring use of shift to type common contractions. This layout has significantly increased my typing speed in C++, C, Java, and Perl, and somewhat increased it in LISP and Python.

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  • C++ cin questions

    - by Kim
    This seems to be weird: int main(int argc, char* argv[]) { cout << "function main() .." << '\n'; char ch = 0; double number_value=1.1; cin >> ch; cin.putback(ch); cin >> number_value; cout << "1 .. " << " " << cin.good() << " " << number_value << '\n'; cin >> number_value; cout << "2 .. " << " " << cin.good() << " " << number_value << '\n'; return 0; } If I input the following: 7a 1 I get the following: function main() .. 7a 1 1 .. 1 7 2 .. 0 0 I understand the: 1 .. 1 7 but why the variable number_value is 0. cin.good() shows failure so nothing would have read and the value in number_value from the previous assignment would remain. I expect the value of 7.

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  • Advanced Regex: Smart auto detect and replace URLs with anchor tags

    - by Robert Koritnik
    I've written a regular expression that automatically detects URLs in free text that users enter. This is not such a simple task as it may seem at first. Jeff Atwood writes about it in his post. His regular expression works, but needs extra code after detection is done. I've managed to write a regular expression that does everything in a single go. This is how it looks like (I've broken it down into separate lines to make it more understandable what it does): 1 (?<outer>\()? 2 (?<scheme>http(?<secure>s)?://)? 3 (?<url> 4 (?(scheme) 5 (?:www\.)? 6 | 7 www\. 8 ) 9 [a-z0-9] 10 (?(outer) 11 [-a-z0-9/+&@#/%?=~_()|!:,.;cšžcd]+(?=\)) 12 | 13 [-a-z0-9/+&@#/%?=~_()|!:,.;cšžcd]+ 14 ) 15 ) 16 (?<ending>(?(outer)\))) As you may see, I'm using named capture groups (used later in Regex.Replace()) and I've also included some local characters (cšžcd), that allow our localised URLs to be parsed as well. You can easily omit them if you'd like. Anyway. Here's what it does (referring to line numbers): 1 - detects if URL starts with open braces (is contained inside braces) and stores it in "outer" named capture group 2 - checks if it starts with URL scheme also detecting whether scheme is SSL or not 3 - start parsing URL itself (will store it in "url" named capture group) 4-8 - if statement that says: if "sheme" was present then www. part is optional, otherwise mandatory for a string to be a link (so this regular expression detects all strings that start with either http or www) 9 - first character after http:// or www. should be either a letter or a number (this can be extended if you'd like to cover even more links, but I've decided not to because I can't think of a link that would start with some obscure character) 10-14 - if statement that says: if "outer" (braces) was present capture everything up to the last closing braces otherwise capture all 15 - closes the named capture group for URL 16 - if open braces were present, capture closing braces as well and store it in "ending" named capture group First and last line used to have \s* in them as well, so user could also write open braces and put a space inside before pasting link. Anyway. My code that does link replacement with actual anchor HTML elements looks exactly like this: value = Regex.Replace( value, @"(?<outer>\()?(?<scheme>http(?<secure>s)?://)?(?<url>(?(scheme)(?:www\.)?|www\.)[a-z0-9](?(outer)[-a-z0-9/+&@#/%?=~_()|!:,.;cšžcd]+(?=\))|[-a-z0-9/+&@#/%?=~_()|!:,.;cšžcd]+))(?<ending>(?(outer)\)))", "${outer}<a href=\"http${secure}://${url}\">http${secure}://${url}</a>${ending}", RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase); As you can see I'm using named capture groups to replace link with an Anchor tag: "${outer}<a href=\"http${secure}://${url}\">http${secure}://${url}</a>${ending}" I could as well omit the http(s) part in anchor display to make links look friendlier, but for now I decided not to. Question I would like my links to be replaced with shortenings as well. So when user copies a very long link (for instance if they would copy a link from google maps that usually generates long links) I would like to shorten the visible part of the anchor tag. Link would work, but visible part of an anchor tag would be shortened to some number of characters. I could as well append ellipsis at the end of at all possible (and make things even more perfect). Does Regex.Replace() method support replacement notations so that I can still use a single call? Something similar as string.Format() method does when you'd like to format values in string format (decimals, dates etc...).

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  • how to add a function to that program, and call that function from the command line in the function

    - by user336291
    a#include "smallsh.h" /*include file for example*/ /*program buffers and work pointers*/ static char inpbuf[MAXBUF], tokbuf[2*MAXBUF], *ptr = inpbuf, *tok = tokbuf; userin(p) /*print prompt and read a line*/ char *p; { int c, count; /*initialization for later routines*/ ptr = inpbuf; tok = tokbuf; /*display prompt*/ printf("%s ",p); for(count = 0;;) { if((c = getchar()) == EOF) return(EOF); if(count<MAXBUF) inpbuf[count++] = c; if(c == '\n' && count <MAXBUF) { inpbuf[count] = '\0'; return(count); } /*if line too long restart*/ if(c == '\n') { printf("smallsh:input line too long\n"); count = 0; printf("%s",p); } } } gettok(outptr) /*get token and place into tokbuf*/ char **outptr; { int type; *outptr = tok; /*strip white space*/ for(;*ptr == ' ' || *ptr == '\t'; ptr++) ; *tok++ = *ptr; switch(*ptr++) { case '\n': type = EOL; break; case '&': type = AMPERSAND; break; case ';': type = SEMICOLON; break; case '#': type = POUND; break; default: type = ARG; while(inarg(*ptr)) *tok++ = *ptr++; } *tok++ = '\0'; return(type); } static char special[]= {' ', '\t', '&', ':', '\n', '\0'}; inarg(c) /*are we in an ordinary argument*/ char c; { char *wrk; for(wrk = special;*wrk != '\0';wrk++) if(c == *wrk) return(0); return(1); } #include "smallsh.h" procline() /*process input line*/ { char *arg[MAXARG+1]; /*pointer array for runcommand*/ int toktype; /*type of token in command*/ int narg; /*number of arguments so far*/ int type; /*FOREGROUND or BACKGROUND*/ for(narg = 0;;) { /*loop FOREVER*/ /*take action according to token type*/ switch(toktype = gettok(&arg[narg])) { case ARG: if(narg<MAXARG) narg++; break; case EOL: case SEMICOLON: case AMPERSAND: case POUND: type = (toktype == AMPERSAND) ? BACKGROUND : FOREGROUND; if(narg!=0) { arg[narg] = NULL; runcommand(arg, type); } if((toktype == EOL)||(toktype=POUND)) return; narg = 0; break; } } } #include "smallsh.h" /*execute a command with optional wait*/ runcommand(cline,where) char **cline; int where; { int pid, exitstat, ret; if((pid = fork()) <0) { perror("smallsh"); return(-1); } if(pid == 0) { /*child*/ execvp(*cline, cline); perror(*cline); exit(127); } /*code for parent*/ /*if background process print pid and exit*/ if(where == BACKGROUND) { printf("[Process id %d]\n", pid); return(0); } /*wait until process pid exists*/ while( (ret=wait(&exitstat)) != pid && ret != -1) ; return(ret == -1 ? -1 : exitstat); } #include "smallsh.h" char *prompt = "Command>"; /*prompt*/ main() { while(userin(prompt) != EOF) procline(); }

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