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  • How to use Private Inheritence aka C++ in C# and Why not it is present in C#

    - by Vijay
    I know that private inheritance is supported in C++ and only public inheritance is supported in C#. I also came across an article which says that private inheritance usually defines a HAS-A relationship and kind of an aggregation relationship between the classes. EDIT: C++ code for private inheritance: The "Car has-a Engine" relationship can also be expressed using private inheritance: class Car : private Engine { // Car has-a Engine public: Car() : Engine(8) { } // Initializes this Car with 8 cylinders using Engine::start; // Start this Car by starting its Engine }; Now, Is there a way to create a HAS-A relationship between C# classes which is one of the thing that I would like to know - HOW? Another curious question is why doesn't C# support the private (and also protected) inheritance ? - Is not supporting multiple implementation inheritance a valid reason or any other? Is private (and protected) inheritance planned for future versions of C#? Will supporting the private (and protected) inheritance in C# make it a better and widely used language?

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  • Covariance and Contravariance on the same type argument

    - by William Edmondson
    The C# spec states that an argument type cannot be both covariant and contravariant at the same time. This is apparent when creating a covariant or contravariant interface you decorate your type parameters with "out" or "in" respectively. There is not option that allows both at the same time ("outin"). Is this limitation simply a language specific constraint or are there deeper, more fundamental reasons based in category theory that would make you not want your type to be both covariant and contravariant? Edit: My understanding was that arrays were actually both covariant and contravariant. public class Pet{} public class Cat : Pet{} public class Siamese : Cat{} Cat[] cats = new Cat[10]; Pet[] pets = new Pet[10]; Siamese[] siameseCats = new Siamese[10]; //Cat array is covariant pets = cats; //Cat array is also contravariant since it accepts conversions from wider types cats = siameseCats;

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  • ASPX ajax form post help

    - by StealthRT
    Hey all, i have this peice of code that allows a user to select a jpg image, resize it and uploads it to the server driectory. The problem being is that it reloads the aspx page when it saves the image. My question is-is there any way to do this same thing but with ajax so that it doesn't leave the page after submitting it? I've done this pleanty of times with classic asp pages but never with a aspx page. Here is the code for the ASPX page: <%@ Page Trace="False" Language="vb" aspcompat="false" debug="true" validateRequest="false"%> <%@ Import Namespace=System.Drawing %> <%@ Import Namespace=System.Drawing.Imaging %> <%@ Import Namespace=System.Drawing.Text %> <%@ Import Namespace=System %> <%@ Import Namespace=System.IO %> <%@ Import Namespace=System.Web %> <%@ Import Namespace=System.ServiceProcess %> <%@ Import Namespace=Microsoft.Data.Odbc %> <%@ Import Namespace=System.Data.Odbc %> <%@ Import Namespace=MySql.Data.MySqlClient %> <%@ Import Namespace=MySql.Data %> <%@ Import Namespace=System.Drawing.Drawing2D %> <%@ Import Namespace="System.Data" %> <%@ Import Namespace="System.Data.ADO" %> <%@ Import Namespace=ADODB %> <SCRIPT LANGUAGE="VBScript" runat="server"> const Lx = 200 const Ly = 60 const upload_dir = "/img/avatar/" const upload_original = "tmpAvatar" const upload_thumb = "thumb" const upload_max_size = 256 dim fileExt dim newWidth, newHeight as integer dim l2 dim fileFld as HTTPPostedFile Dim originalimg As System.Drawing.Image dim msg dim upload_ok as boolean </script> <% Dim theID, theEmail, maleOrFemale theID = Request.QueryString("ID") theEmail = Request.QueryString("eMail") maleOrFemale = Request.QueryString("MF") randomize() upload_ok = false if lcase(Request.ServerVariables("REQUEST_METHOD"))="post" then fileFld = request.files(0) if fileFld.ContentLength > upload_max_size * 1024 then msg = "Sorry, the image must be less than " & upload_max_size & "Kb" else try fileExt = System.IO.Path.GetExtension(fileFld.FileName).ToLower() if fileExt = ".jpg" then originalImg = System.Drawing.Image.FromStream(fileFld.InputStream) if originalImg.Height > Ly then newWidth = Ly * (originalImg.Width / originalImg.Height) newHeight = Ly end if Dim thumb As New Bitmap(newWidth, newHeight) Dim gr_dest As Graphics = Graphics.FromImage(thumb) dim sb = new SolidBrush(System.Drawing.Color.White) gr_dest.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality gr_dest.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality gr_dest.FillRectangle(sb, 0, 0, thumb.Width, thumb.Height) gr_dest.DrawImage(originalImg, 0, 0, thumb.Width, thumb.Height) try originalImg.save(Server.MapPath(upload_dir & upload_original & fileExt), originalImg.rawformat) thumb.save(Server.MapPath(upload_dir & theID & fileExt), originalImg.rawformat) msg = "Uploaded " & fileFld.FileName & " to " & Server.MapPath(upload_dir & upload_original & fileExt) upload_ok = true File.Delete(Server.MapPath(upload_dir & upload_original & fileExt)) catch msg = "Sorry, there was a problem saving your avatar. Please try again." end try if not thumb is nothing then thumb.Dispose() thumb = nothing end if else msg = "That image does not seem to be a JPG. Upload only JPG images." end if catch msg = "That image does not seem to be a JPG." end try end if if not originalImg is nothing then originalImg.Dispose() originalImg = nothing end if end if %><head> <meta http-equiv="pragma" content="no-cache" /> </head> <html> <script type="text/javascript" src="js/jquery-1.3.min.js"></script> <form enctype="multipart/form-data" method="post" runat="server" id="sendImg"> <input type="file" name="upload_file" id="upload_file" style="-moz-opacity: 0; opacity:0; filter: alpha(opacity=0); margin-top: 5px; float:left; cursor:pointer;" onChange="$('#sendImg').submit();" > <input type="submit" value="Upload" style="visibility:hidden; display:none;"> </form> </body> </html> Any help would be great! :o) David

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  • linear interpolation on 8bit microcontroller

    - by JB
    I need to do a linear interpolation over time between two values on an 8 bit PIC microcontroller (Specifically 16F627A but that shouldn't matter) using PIC assembly language. Although I'm looking for an algorithm here as much as actual code. I need to take an 8 bit starting value, an 8 bit ending value and a position between the two (Currently represented as an 8 bit number 0-255 where 0 means the output should be the starting value and 255 means it should be the final value but that can change if there is a better way to represent this) and calculate the interpolated value. Now PIC doesn't have a divide instruction so I could code up a general purpose divide routine and effectivly calculate (B-A)/(x/255)+A at each step but I feel there is probably a much better way to do this on a microcontroller than the way I'd do it on a PC in c++ Has anyone got any suggestions for implementing this efficiently on this hardware?

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  • How to create playable FLV video from part of FLV file using FFMPEG?

    - by Ole Jak
    So we had real FLV video file. we had devided it into 3 parts (more or less equal, not looking into structure orcontext). We have taken second part and forgot about first 2. Video contained audio and video track. mp3 and on vp6. Is it any how possible to play thsat second part after sending to ffmpeg some command? So how to (using any FFMPEG API (in general in any programming language) or using command line) turn bytearray into playable video? (knowing what format video was created in and some other data like used codecs )

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  • Cross Platform Tips, Tricks & Gotchas

    - by codeelegance
    If you've worked on a cross platform development project: What did you learn from the experience? What worked? What didn't? What problems did you run into and how did you solve them? Did you aim for consistent appearance and functionality across all platforms or try to take advantage of each platform's strengths? What language and cross platform libraries did you use and did they live up to their claims? Was it a desktop application or web-based?

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  • plpgsql function to generate random readable strings

    - by Peter
    Hi I have written the following function but it's isn't returning anything when I run it. Can somebody help identify the issue? CREATE OR REPLACE FUNCTION GenerateReadableRandomString ( len INT ) RETURNS varchar AS $$ DECLARE validchars VARCHAR; randomstr VARCHAR; randint INT; i INT; BEGIN validchars := 'ABCEFHJKLMNPRTWXY3478'; i := 0; LOOP randint := ceil(random() * char_length(validchars)); randomstr := randomstr || substring(validchars from randint for 1); i := i + 1; EXIT WHEN i = len; END LOOP; RETURN randomstr; END; $$ LANGUAGE plpgsql;

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  • Python 'datetime.datetime' object is unsubscriptable

    - by Robert
    First, I am NOT a python developer. I am trying to fix an issue within a python script that is being executed from the command line. This script was written by someone who is no longer around, and no longer willing to help with issues. This is python 2.5, and for the moment it cannot be upgraded. Here are the lines of code in question: start_time = datetime.strptime(str(paf.Start),"%Y-%m-%d %H:%M:%S") dict_start = datetime(*start_time[:6]) end_time = datetime.strptime(str(paf.End),"%Y-%m-%d %H:%M:%S") dict_end = datetime(*end_time[:6]) When this code is ran, it generates an error with the description: 'datetime.datetime' object is unsubscriptable. This is the import statement: from datetime import datetime I have a feeling that this is something simple, but not being my native language and Google not yielding any valuable results, I am stuck. I have tried a couple of different import methods, yielding different errors, but all with these statements. Any help on this would be greatly appreciated.

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  • Aaron Hillegass Chapter 18 Challenge Question

    - by jasonbogd
    I am working through Aaron Hillegass' Cocoa Programming for Mac OS X and am doing the challenge for Chapter 18. Basically, the challenge is to write an app that can draw ovals using your mouse, and then additionally, add saving/loading and undo support. I'm trying to think of a good class design for this app that follows MVC. Here's what I had in mind: Have a NSView-subclass that represents an oval (say JBOval) that I can use to easily draw an oval. Have a main view (JBDrawingView) that holds JBOvals and draws them. The thing is that I wasn't sure how to add archiving. Should I archive each JBOval? I think this would work, but archiving an NSView doesn't seem very efficient. Any ideas on a better class design? Thanks.

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  • TimeSpan to Localized String in C#

    - by MadBoy
    Is there an easy way (maybe built in solution) to convert TimeSpan to localized string? For example new TimeSpan(3, 5, 0); would be converted to 3 hours, 5minutes (just in polish language). I can of course create my own extension: public static string ConvertToReadable(this TimeSpan timeSpan) { int hours = timeSpan.Hours; int minutes = timeSpan.Minutes; int days = timeSpan.Days; if (days > 0) { return days + " dni " + hours + " godzin " + minutes + " minut"; } else { return hours + " godzin " + minutes + " minut"; } } But this gets complicated if i want to have proper grammar involved.

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  • help installing odfWeave

    - by Andreas
    This is not a programming question per se - but I hope someone can help: I can't install odfWeave - it looks like the problem is with the package XML - which i can't install either. checking for xml2-config... no Cannot find xml2-config ERROR: configuration failed for package ‘XML’ * removing ‘/home/andreas/R/i486-pc-linux-gnu-library/2.10/XML’ * installing source package ‘odfWeave’ ... ** R ** inst ** preparing package for lazy loading Warning in library(pkg, character.only = TRUE, logical.return = TRUE, lib.loc = lib.loc) : there is no package called 'XML' Error : package 'XML' could not be loaded ERROR: lazy loading failed for package ‘odfWeave’ * removing ‘/home/andreas/R/i486-pc-linux-gnu-library/2.10/odfWeave’ Any help much appreciated System: ubuntu 9.04

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  • Usng Rails ActiveRecord relationships

    - by Brian Goff
    I'm a newbie programmer, been doing shell scripting for years but have recently taken on OOP programming using Ruby and am creating a Rails application. I'm having a hard time getting my head wrapped around how to use my defined model relationships. I've tried searching Google, but all I can come up with are basically cheat sheets for what has_many, belongs_to, etc all mean. This stuff is easy to define & understand, especially since I've done a lot of work directly with SQL. What I don't understand is how to actually used those defined relationships. In my case I have 3 models: Locations Hosts Services Relationships (not actual code, just for shortening it): Services belongs_to :hosts Hosts has_many :services belongs_to :locations Locations has_many :hosts In this case I want to be able to display a column from Locations while working with Services. In SQL this is a simple join, but I want to do it the Rails/Ruby way, and also not use SQL in my code or redefine my joins.

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  • Why can't I download a whole image file with urllib2.urlopen()

    - by John Gann
    When I run the following code, it only seems to be downloading the first little bit of the file and then exiting. Occassionally, I will get a 10054 error, but usually it just exits without getting the whole file. My internet connection is crappy wireless, and I often get broken downloads on larger files in firefox, but my browser has no problem getting a 200k image file. I'm new to python, and programming in general, so I'm wondering what nuance I'm missing. import urllib2 xkcdpic=urllib2.urlopen("http://imgs.xkcd.com/comics/literally.png") xkcdpicfile=open("C:\\Documents and Settings\\John Gann\\Desktop\\xkcd.png","w") while 1: chunk=xkcdpic.read(4028) if chunk: print chunk xkcdpicfile.write(chunk) else: break

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  • Touchscreen using sound input?

    - by ricardowong
    Hi, i don't really know if it is actually possible, but i believe that it can be made. How possible is it to make a program that recognizes different sound bouncing from the screen and turn it into a position that will obviously be later fed to the mouse. I know that it sounds kind of dumb, but lately i've been noticing that a very dull, strong sound is made when touching the screen, and that sound varies when doing so at different positions. Probably the microphone "hears" differently because the screen acts as a drum with the casing. Anyways, what do you think, anyone has any experience programming with sound?

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  • Looking for calculator source code, BSD-licensed

    - by Horace Ho
    I have an urgent project which need many functions of a calculator (plus a few in-house business rule formulas). As I won't have time to re-invent the wheel so I am looking for source code directly. Requirements: BSD licensed (GPL won't help) in c/c++ programming language 32-bit CPU minimum dependency on platform API/data structure best with both RPN and prefix notation supported emulator/simulator code also acceptable (if not impossible to add custom formula) with following functions (from wikipedia) Scientific notation for calculating large numbers floating point arithmetic logarithmic functions, using both base 10 and base e trigonometry functions (some including hyperbolic trigonometry) exponents and roots beyond the square root quick access to constants such as pi and e plus hexadecimal, binary, and octal calculations, including basic Boolean math fractions optional statistics and probability calculations complex numbers programmability equation solving

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  • A strong case for WF

    - by Pita.O
    Hi guys, I have struggled for so long to find a compelling use case for workflow (ie: WF) as against regular imperative programming. Each time I fall back to the conclusion that I should just leave WF out or defer getting into it until later. But I keep having this nagging feeling that there's something am missing. Does anyone know any book that truly makes a strong case for the Workflow way? The book has to (i) teach WF well, and (ii) show using appropriate use cases that WF made an implementation easy to do than if we just did our regular straight coding. I will appreciate it.

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  • jquery animate and image resize flickering

    - by denadai2
    Hi, i've a problem with a resize effect that i've done in http://www.mcz-scenario.it. When you click on a language, you can see the "background" image transferring into a certain position of the screen. this is the image: <img id="lago" src="http://www.mcz-scenario.it/images/lago.jpg" height="1070" width="1600" alt="lago" /> And this is the "resize" effect $("#lago").animate({ height: 148, width: 264, top: endPosition2.top+42, left: endPosition2.left+350+26}, 4000); Now... I see some flickering running this animation in Firefox. How can i handle this? Is it normal because the image is too large? Help me please :( THX

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  • Libreoffice Calc run macro with HYPERLINK

    - by Kurt Borno
    I'm trying to use hyperlinks instead of buttons to run Basic macros. It seems to be more natural to me because hyperlinks are directly connected to a cell and buttons are not. I'm using the following Formula: =HYPERLINK("vnd.sun.star.script:Standard.Module1.Test?language=Basic&location=document";"Check") It should call the Subroutine Test placed in the document's macros under Standard.Module1 and display the Text 'Check' in the Cell it is written. This works absolutely fine with libreoffice 3.6.1.2 but it doesn't work at all with version 4.1.4.2. I can't see any errors it just happens nothing at all. I tried to simply click the Hyperlink and also to hold CTRL and click it. Same result - nothing. When I use a button the macro works as expected. Does anyone know how to solve this problem?

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  • Email sent by ActionMailer is taking six hours to deliver mail.

    - by grg-n-sox
    So I have been asked to help maintain a website that uses Ruby on Rails. Now, let me just say I've been programming Ruby for awhile but I am still new to Rails. The first problem brought to my attention is how the activation email takes about six hours to arrive. It would be one thing if the email was not being sent due to errors but it is being send correctly, just slow. Also the server this is running on is also its own SMTP. I checked how the email was being formatted before calling the setup_email method and everything looks okay. I even dug into the ActionMailer lib and read through the files there and didn't see anything out of the ordinary. So what is most likely causing the email to take six hours to deliver?

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  • .net multilingual cms

    - by Adam
    i am planning a simple, dual-language website and i'd like to use a .net based cms but i can't find anything suitable. i have experience with dotnetnuke and sharepoint but neither fit the bill - dotnetnuke does not do dynamic site elements multi-lingually & sharepoint is a monster PITA no matter what angle you look at it :). i am on the verge of choosing Joomla! & Joom!Fish. they fit the bill nicely, with one exception: i would like to create some cms plug-ins and i would much prefer to write them in .net. any suggestions?

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  • How to detect defunct processes on Linux?

    - by Hakan
    I have a parent and a child process written in C language. Somewhere in the parent process HUP signal is sent to the child. I want my parent process to detect if the child is dead. But when I send SIGHUP, the child process becomes a zombie. How can I detect if the child is a zombie in the parent process? I try the code below, but it doesn't return me the desired result since the child process is still there but it is defunct. kill(childPID, 0); One more question; can I kill the zombie child without killing the parent? Thanks.

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  • iPhone Foundation - performance implications of mutable and xxxWithCapacity:0

    - by Adam Eberbach
    All of the collection classes have two versions - mutable and immutable, such as NSArray and NSMutableArray. Is the distinction merely to promote careful programming by providing a const collection or is there some performance hit when using a mutable object as opposed to immutable? Similarly each of the collection classes has a method xxxxWithCapacity, like [NSMutableArray arrayWithCapacity:0]. I often use zero as the argument because it seems a better choice than guessing wrongly how many objects might be added. Is there some performance advantage to creating a collection with capacity for enough objects in advance? If not why isn't the function something like + (id)emptyArray?

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  • Superfluous python parameters

    - by Leif Andersen
    I've noticed a discrepancy in the way that python parameters are called. In every other language I've dealt with, you either have foo() meaning either no parameters, or as many parameters as you like, or foo(arg1, arg2,...,argn) where you pass in the same number of parameters to define the function and call it. In python however, I've noticed that the function definitions, and when the function is called, can have two different parameters sets, this usually consists of: class foo(object): def bar(self, arg1, arg2): pass However, when I want to call the function, all I have to do is: zoo = foo() zoo.bar(arg1, arg2) Where did the self parameter go? Thank you.

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  • How to check misspelled email during user registration

    - by Nulldevice
    I use an email registration and confirmation in my project (yes, I know about OpenID. In my counry, a main email service lack it). Sometimes users misspell their email addresses. I know about this due to "message could not be delivered" letters in a mailbox. A misspelled address is absolutely correct, because I check it with a regular expression - say, [email protected] intstead of [email protected]. And I do not want to duplicate a email field in a registration form (who likes it?). Request processing routine cannot wait for email delivery - it could take an unpredictable time. So, my script will return to user a confirmation message "An email was sent". And the user will wait for it forever (of cause, not - he/she will turn to an alternative project with a more perfect registration system). Does someone knows how it can be improved (in any programming language)?

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  • displaying web pages over web views in collection view using cocoa bindings

    - by Miraaj
    Hi all, I tried sample example given at this link - Collection View Programming Guide It is simple and it worked. Considering it as a reference I tried a simple application which will show a collection view of web views with some web page displayed over each web view. The model class has two properties: NSString *pageName, and NSURL *pageURL. I then followed each and every step written in tutorial above with required modifications but I was caught in the step - How to bind web view to collection view item? In binding tab it shows three possibilities : Editable, Hidden, Tool tip but none of these is working. Can anyone suggest me way to accomplish my requirement? Thanks, Miraaj

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