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  • C++: Template functor cannot deduce reference type

    - by maciekp
    I've got a functor f, which takes a function func and a parameter t of the same type as func. I cannot pass g to f because of compilation error (no matching function for call to f(int&, void (&)(int&)) ). If g would take non-reference parameter g(int s), compilation finishes. Or if I manually specify template parameter f(i, g), compilation also finishes. template<typename T> void f(T t, void (*func)(T)) {} void g(int& s) {} int main(int, char*[]) { int i = 7; f(i, g); // compilation error here return 0; } How can I get deduction to work?

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  • What's the most straightforward way to typeset MLA-style college essays in LaTeX?

    - by bcat
    I've been using LaTeX for a little while now to typeset my algorithms homework, and I really like the quality of the output as well as the ease-of-use. I'd like to starting using LaTeX in other classes as well, but non–computer-science subjects have more stringent formatting requirements than I've come across in CS. Most classes that require essays want them to be formatted in MLA style, but I'm not sure what to best way to do that using LaTeX is. I've tried Googling "latex mla" and other similar things, but I've found many different MLA templates, and my LaTeX skills aren't good enough to determine which is the best. Is anyone else using LaTeX for "normal" essays, and, if so, how are you doing it?

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  • C++, create an instance from a static method

    - by Manux
    Hello, let's say I want my users to use only one class, say SpecialData. Now, this data class would have many methods, and depending on the type of data, the methods do different things, internally, but return externally similar results. Therefore my wanting to have one "public" class and other "private", child classes that would change the behavior of methods, etc... It would be amazingly more simple for some types of data that need to be built to do something like this: SpecialData& sm = SpecialData::new_supermatrix(); and new_supermatrix() would return a SuperMatrix instance, which inherits from most behaviors of SpecialData. my header: static SpecialData& new_supermatrix(); my cpp: SpecialData& SpecialData::new_supermatrix()(){ return SuperMatrix(MATRIX_DEFAULT_MAGNITUDE,1000,1239,FLOAT32,etc...); } The problem is, I get this error, which is probably logical due to the circumstances: invalid initialization of non-const reference of type ‘SpecialData&’ from a temporary of type ‘SpecialData’ So, any ideas?

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  • Using control from a separate class in C#

    - by DazSlayer
    I have a program that dynamically creates controls when it starts, it works just fine when the code to do this is in the class of the actual form. I tried moving the code to a separate class and found that I could not use Controls.Add(). How can I add controls to the Form from a separate class? This is what I have so far: TextBox txtbx = new TextBox(); txtbx.Text = "asd" + x.ToString(); txtbx.Name = "txtbx" + x.ToString(); txtbx.Location = new Point(10, (20 * x)); txtbx.Height = 20; txtbx.Width = 50; Controls.Add(txtbx); Error 1 The name 'Controls' does not exist in the current context

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  • MVC Routes - How to get a URL?

    - by Seattle Leonard
    In my current project we have a notification system. When an oject is added to another objects collection, an email is sent to those who are subscibed to the parent object. This happens on the object layer and not in the View or Controller. Here's the problem: Although we can say who created what with what information in the email, we cannot embed links to those objects in the email because in the object layer there is no access to a UrlHelper. To construct a UrlHelper you need a RequestContext, which again does not exist on the object layer. Question: I want to make a helper class to create the url's for me. How can I create an object that will generate these urls without a request context? Is it possible?

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  • Check if a class is subclass of another class in Java

    - by craesh
    Hi! I'm playing around with Java's reflection API and trying to handle some fields. Now I'm stuck with identifying the type of my fields. Strings are easy, just do myField.getType().equals(String.class). The same applies for other non-derived classes. But how do I check derived classes? E.g. LinkedList as subclass of List. I can't find any isSubclassOf(...) or extends(...) method. Do I need to walk through all getSuperClass() and find my supeclass by my own? Thanks! craesh

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  • Another Nim's Game Variant

    - by Terry Smith
    Given N binary sequence Example : given one sequence 101001 means player 0 can only choose a position with 0 element and cut the sequence from that position {1,101,1010} player 1 can only choose a position with 1 element ans cut the sequence from that position {null,10,101000} now player 0 and player 1 take turn cutting the sequence, on each turn they can cut any one non-null sequence, if a player k can't make a move because there's no more k element on any sequence, he lose. Assume both player play optimally, who will win ? I tried to solve this problem with grundy but i'm unable to reduce the sequence to a grundy number because it both player don't have the same option to move. Can anyone give me a hint to solve this problem ?

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  • Sound Manager Classes for Windows (C# or C++ .Net 2.0)

    - by Yakov
    Hi guys! I need some classes for playing short wav sounds, this classes would load this wav files into memory when an instance created, play sounds in background when needed, release this wav files from memory when an instance disposed. How can I do this on C# for windows (.Net 2.0)? (Win API's sndPlaySound, OpenAL or may be any wrapper) Ideally I would love to find an exist solution that simple and able to solve my task. Do you know any solutions for this issue? Thankx for your time.

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  • how do you load files in windows phone 7?

    - by matt
    do you seriously have to make your own content pipeline project for every single type of file you want to load? Microsoft just seem to be pretending that the iphone doesn't exist (even though they are now paying devs to port between them). I'm trying to port my game from the iphone to winmo7, and I already have a nice asset pipeline set up for exporting textures in the exact format we want (16 bit fmts ect) I just want to be able to open a file and read it, just like I would on any other platform. I have tried System.IO.File.OpenText("atextfile.txt"), but it says that function is "RESTRICTED!!!!" I have tried just adding the txt file to the content project, setting its properties to "content" and "copy always" and then trying to open it doing this.Content.Load("atextfile.txt"); with and without the extension, says it can't find the file.

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  • Streaming multiple TObjects to a TMemoryStream

    - by Altar
    I need to store multiple objects (most of them are TObject/non persistent) to a TMemoryStream, save the stream to disk and load it back. The objects need to be streamed one after each other. Some kind of universal container. I started to make several functions that store stuff to stream - for example function StreamReadString(CONST MemStream: TMemoryStream): string; StreamWriteString(CONST MemStream: TMemoryStream; s: string); However, it seems that I need to rewrite a lot of code. One of the many examples is TStringList.LoadFromStream that will not work so it needs to be rewritten. This is because TStringList needs to be the last object in the stream (it reads from current position to the end of the stream). Anybody knows a library that provide basic functionality like this? I am using Delphi 7 so RTTI won't help too much.

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  • Find java classes implementing an interface

    - by Linor
    Some time ago, I came across a piece of code, that used some piece of standard java functionality to locate the classes that implemented a given interface. I know the the functions were hidden in some non logical place, but they could be used for other classes as the package name implied. Back then I did not need it, so I forgot about it, but now I do, and I can't seem to find the functions again. Does anyone know where to find these functions? edit: I'm not looking for any IDE functions or anything, but rather something that can be executed within the java application.

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  • The remote server returned an error: (407) Proxy Authentication Required

    - by chris
    I'm getting this error when I call a web service: "The remote server returned an error: (407) Proxy Authentication Required". I get the general idea and I can get the code to work by adding myProxy.Credentials= NetworkCredential("user", "password", "domain"); or by using DefaultCredentials in code. My problem is that the call to the web service works in production without this. It seems like there is a non code solution involving Machine.config, but what is it? At the moment I can't get to the production boxes machine.config file to see what that looks like. I tried updating my machine.config as follows, but I still get the 407 error.

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  • MySQL - Join as zero if record Not IN

    - by Zurahn
    To explain by example, take two tables, A and B Table A id foo 1 x 2 y 3 z Table B id aid bar 1 3 50 2 1 100 An example join SELECT foo, bar FROM a, b WHERE a.id = b.aid; Garners a result of foo bar z 50 x 100 What I would like to do is get all values of foo and for any instances where there isn't a corresponding bar value, return 0 for that column. My best guess was something along the lines of SELECT foo, bar AS br FROM a, b WHERE a.id = b.aid OR a.id NOT IN (SELECT aid FROM b); But that returns duplicates and non-zero values for bar. Possible?

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  • Django design question: extending User to make users that can't log in

    - by jobrahms
    The site I'm working on involves teachers creating student objects. The teacher can choose to make it possible for a student to log into the site (to check calendars, etc) OR the teacher can choose to use the student object only for record keeping and not allow the student to log in. In the student creation form, if the teacher supplies a username and a password, it should create an object of the first kind - one that can log in, i.e. a regular User object. If the teacher does not supply a username/password, it should create the second type. The other requirement is that the teacher should be able to go in later and change a non-logging-in student to the other kind. What's the best way to design for this scenario? Subclass User and make username and password not required? What else would this affect?

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  • What platforms have something other than 8-bit char?

    - by Craig McQueen
    Every now and then, someone on SO points out that char (aka 'byte') isn't necessarily 8 bits. It seems that 8-bit char is almost universal. I would have thought that for mainstream platforms, it is necessary to have an 8-bit char to ensure its viability in the marketplace. Both now and historically, what platforms use a char that is not 8 bits, and why would they differ from the "normal" 8 bits? When writing code, and thinking about cross-platform support (e.g. for general-use libraries), what sort of consideration is it worth giving to platforms with non-8-bit char? In the past I've come across some Analog Devices DSPs for which char is 16 bits. DSPs are a bit of a niche architecture I suppose. (Then again, at the time hand-coded assembler easily beat what the available C compilers could do, so I didn't really get much experience with C on that platform.)

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  • Incorrect error

    - by jspooner
    If you assign an invalid date (like December 39th) to a datetime column ActiveRecord returns a "can't be blank" error when is should probably return an error like "Not a valid date" My question. Is this expected rails behavior, a bug or, something that I could patch? class ExerciseLog < ActiveRecord::Base validates_presence_of :scheduled_datetime end Fire up the console. e = Log.new # lets set a date for Dec 39th which obviously doesn't exist e.scheduled_datetime = "2010-12-39" e.save => false # this is the confusing message since our form did post a valid date e.errors.on(:scheduled_datetime) => "can't be blank" e.scheduled_datetime = "2010-12-30" e.save => true I discovered this issue when I accidentally transposed the month and day values. btw This is in Rails 2.3.5

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  • What happens when a computer program runs?

    - by gaijinco
    I know the general theory but I can't fit in the details. I know that a program resides in the secondary memory of a computer. Once the program begins execution it is entirely copied to the RAM. Then the processor retrive a few instructions (it depends on the size of the bus) at a time, puts them in registers and executes them. I also know that a computer program uses two kinds of memory: stack and heap, which are also part of the primary memory of the computer. The stack is used for non-dynamic memory, and the heap for dynamic memory (for example, everything related to the new operator in C++) What I can't understand is how those two things connect. At what point is the stack used for the execution of the instructions? Instructions go from the RAM, to the stack, to the registers?

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  • Where to get the import ij.* package from?

    - by razshan
    What do I need to do to successfully the import ij package? I get an error: ITCN_.java:1: package ij does not exist The imports are: import ij.*; import ij.io.*; import ij.gui.*; import ij.process.*; import ij.measure.*; import ij.plugin.*; import ij.plugin.frame.*; import ij.plugin.filter.PlugInFilter; import java.io.*; import java.awt.*; import java.awt.event.*; import java.util.*; import java.lang.*; import java.text.*;

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  • When does it make sense to use a map?

    - by kiwicptn
    I am trying to round up cases when it makes sense to use a map (set of key-value entries). So far I have two categories (see below). Assuming more exist, what are they? Please limit each answer to one unique category and put up an example. Property values (like a bean) age -> 30 sex -> male loc -> calgary Presence, with O(1) performance peter -> 1 john -> 1 paul -> 1

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  • Is there a way to bring an application's GUI to the current desktop?

    - by Davy8
    Background: Started a fair amount of work before realizing that a Windows Service cannot start an app with a GUI that displays without potential problems. The proper solution of separating the GUI of the app to be started is non-trivial, so I'm trying to think of alternative solutions. There is a GUI to manage the service that is a separate executable, but the process to be launched (actually multiple instances of it) has its own GUI that needs to be shown. It doesn't need to be made visible by the service itself, but it needs to be at least able to be made visible by another process with a visible GUI. The Windows User that is running the service and that needs to see the GUI of the launched process is the same and known at install time. Is there some way to accomplish this or is it back to the drawing board? Also both the service and the app to launch are both our code and modifiable.

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  • Editing a TreeView node doesn't change the TreeNode Key

    - by Blitzz
    I have a TreeView with user-editable nodes. I like to use the node caption as key to my tree node : + Root |+ Node1 ||- SubNode1 ||- SubNode2 |+ Node2 ||- SubNode3 ||- SubNode4 So I can reach a node like this: MyTreeView.Nodes["Root"].Nodes["Node2"].Nodes["SubNode3"] The problem is that, as I allow the user to rename any node, I would need also to change the key of my node in its parent in the AfterLabelEdit handler... which seems (logically) not to be done automatically. Unfortunately, Nodes["blabla"] is readonly, Nodes.Add(string Key, TreeNode Node) doesn't exist, and I can't find a way to do this without throwing (sooner or later) a bad exception. Any idea ?

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  • Routing problem, handling differently online versus local - MVC.net 1.0

    - by VinnyG
    I have there lines in my RegisterToutes : routes.MapRoute("Pages3", "{url1}/{url2}/{url3}", MVC.Page.RedirectTo(), new { url1 = "", url2 = "", url3 = "" }); routes.MapRoute("Pages2", "{url1}/{url2}", MVC.Page.RedirectTo(), new { url1 = "", url2 = "", url3 = "" }); routes.MapRoute("Pages1", "{url1}", MVC.Page.RedirectTo(), new { url1 = "", url2 = "", url3 = "" }); On my local machine and on my demo server (demo.myserver.com/myproject/) it works great for handling the 404, but live(www.mysite.com) it just go to the IIS 404. I have a PageController witch go see if the page exist in the DB and if it don't I return to a 404 view with the status code 404 (Response.StatusCode = 404;) How can I reproduce the same behavior live? Do I need to setup something on IIS? I'm on winserver 2008 using c# and MVC 1.0. Thanks for the help!

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  • MySQL : delete from table that is used in the where clause

    - by Eric
    I am writing a small script to synchronize 2 MySQL tables ( t1 to be 'mirrored' to t2 ) In a step I would like to delete rows inside t2 that has been delete in t1 with the same id. I tried this query : delete from t2 where t2.id in ( select t2.id left join t1 on (t1.id=t2.id) where t1.id is null ) But Mysql forbid me to use t2 in the same time in the delete and in the select (sound logical by the way) Of course, I can split the query into 2 queries : first select IDs, then delete rows with these IDs. My question : do you have a cleaner way to delete row from t2 that does not exist anymore in t1 ? with one query only ?

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  • Is the time cost constant when bulk inserting data into an indexed table?

    - by SiLent SoNG
    I have created an archive table which will store data for selecting only. Daily there will be a program to transfer a batch of records into the archive table. There are several columns which are indexed; while others are not. I am concerned with time cost per batch insertion: - 1st batch insertion: N1 - 2nd batch insertion: N2 - 3rd batch insertion: N3 The question is: will N1, N2, and N3 roughly be the same, or N3 N2 N1? That is, will the time cost be a constant or incremental, with existence of several indexes? All indexes are non-clustered. The archive table structure is this: create table document ( doc_id int unsigned primary key, owner_id int, -- indexed title smalltext, country char(2), year year(4), time datetime, key ix_owner(owner_id) }

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  • Where can I find the transaction protocol used by Automated Teller Machines?

    - by Dave
    I'm doing a grad-school software engineering project and I'm looking for the protocol that governs communications between ATMs and bank networks. I've been googling for quite a while now, and though I'm finding all sorts of interesting information about ATMs, I'm surprised to find that there seems to be no industry standard for high-level communications. I'm not talking about 3DES or low-level transmission protocols, but something along the lines of an Interface Control Document; something that governs the sequence of events for various transactions: verify credentials, withdrawal, check balance, etc. Any ideas? Does anything like this even exist? I can't believe that after all this time the banks and ATM manufacturers are still just making this up as they go. A shorter question: if I wanted to go into the ATM software manufacturing business, where would I start looking for standards?

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