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  • javascript function not working in IE 7

    - by JPro
    Hi, Can anyone please tell me how do I make this script run in IE 7? When I run this , nothing happens. <html> <body> <script language="JavaScript"> function moveSelectedOption() { // Fetch references to the <select> elements. var origin = document.getElementById('origin_select'); var target = document.getElementById('target_select'); // Fetch the selected option and clone it. var option = origin.options[origin.selectedIndex]; var copy = option.cloneNode(true); // Add the clone to the target element. target.add(copy, null); } </script> <select id="origin_select" multiple> <option value="A">A</option> <option value="B">B</option> <option value="C">C</option> </select> <select id="target_select" multiple> <option value="C1">C1</option> </select> <button onclick="moveSelectedOption()">Add</button> </body> </html>

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  • Good Learning Method for Objective-C?

    - by Josh Kahane
    Hi I know this must be asked a millions times and can't be easy to answer as there is o definitive method, but any help would be appreciated, thanks. I have been playing around with all sorts of things in Xcode and with Objective-C, however I can't seem to find a good way of learning things in an efficient way. I have bought the book 'Programming in Objective-C 2.0' and its great but just lays down the basics it seems. I want to learn in the 2D game development direction, then of course 3D after nailing that, if thats the right thing to do? I am 17 currently in year 13, last year of school/A Levels and am almost definitely taking a gap year. Any good, well known reputable courses online or offline (real world)? This is my first programming language, and I am absolutely serious about learning this. One last question, is when learning things online, I have in the past started building a feature and learning a certain aspect in programming only to find out after adding more its slows down the app or its to inefficient. Is the key to use a certain method in a certain situation (being os many ways to do the same thing) or use any of those methods and refine it in your app to make it run smoothly? Sorry, its hard for me to know when I have little experience, thus far. Sorry for rambling on! I would appreciate any help, thank you!

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  • What is Ruby's analog to Python Metaclasses?

    - by Sean Copenhaver
    Python has the idea of metaclasses that, if I understand correctly, allow you to modify an object of a class at the moment of construction. You are not modifying the class, but instead the object that is to be created then initialized. Python (at least as of 3.0 I believe) also has the idea of class decorators. Again if I understand correctly, class decorators allow the modifying of the class definition at the moment it is being declared. Now I believe there is an equivalent feature or features to the class decorator in Ruby, but I'm currently unaware of something equivalent to metaclasses. I'm sure you can easily pump any Ruby object through some functions and do what you will to it, but is there a feature in the language that sets that up like metaclasses do? So again, Does Ruby have something similar to Python's metaclasses? Edit I was off on the metaclasses for Python. A metaclass and a class decorator do very similar things it appears. They both modify the class when it is defined but in different manners. Hopefully a Python guru will come in and explain better on these features in Python. But a class or the parent of a class can implement a __new__(cls[,..]) function that does customize the construction of the object before it is initialized with __init__(self[,..]).

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  • How to call Postgres function returning SETOF record?

    - by Peter
    I have written the following function: -- Gets stats for all markets CREATE OR REPLACE FUNCTION GetMarketStats ( ) RETURNS SETOF record AS $$ BEGIN SELECT 'R approved offer' AS Metric, SUM(CASE WHEN M.MarketName = 'A+' AND M.Term = 24 THEN LO.Amount ELSE 0 end) AS MarketAPlus24, SUM(CASE WHEN M.MarketName = 'A+' AND M.Term = 36 THEN LO.Amount ELSE 0 end) AS MarketAPlus36, SUM(CASE WHEN M.MarketName = 'A' AND M.Term = 24 THEN LO.Amount ELSE 0 end) AS MarketA24, SUM(CASE WHEN M.MarketName = 'A' AND M.Term = 36 THEN LO.Amount ELSE 0 end) AS MarketA36, SUM(CASE WHEN M.MarketName = 'B' AND M.Term = 24 THEN LO.Amount ELSE 0 end) AS MarketB24, SUM(CASE WHEN M.MarketName = 'B' AND M.Term = 36 THEN LO.Amount ELSE 0 end) AS MarketB36 FROM "Market" M INNER JOIN "Listing" L ON L.MarketID = M.MarketID INNER JOIN "ListingOffer" LO ON L.ListingID = LO.ListingID; END $$ LANGUAGE plpgsql; And when trying to call it like this... select * from GetMarketStats() AS (Metric VARCHAR(50),MarketAPlus24 INT,MarketAPlus36 INT,MarketA24 INT,MarketA36 INT,MarketB24 INT,MarketB36 INT); I get an error: ERROR: query has no destination for result data HINT: If you want to discard the results of a SELECT, use PERFORM instead. CONTEXT: PL/pgSQL function "getmarketstats" line 2 at SQL statement I don't understand this output. I've tried using perform too, but I thought one only had to use that if the function doesn't return anything.

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  • cross-platform scripting for windows, Linux, MacOS X

    - by karolrvn
    Hi. I'm looking for cross-platform scripting (language) for windows, Linux, MacOS X. I'm tired of .bat / bash . I would like to do things like for example ,,lock workstation'' at automatic login (I had this in X-Window but the solution was pretty ugly; now, I would like that on MS Windows and not that ugly :-) ). Generally: automate tasks. Or would I be better off with Windows Scripting Host? PowerShell also comes to mind, but that's seems to Windows-only for my taste. Can languages like Python, Ruby, (Java?) interact (elegantly? sensibly?) with WSH? Also things like DBUS, DCOM, etc come to mind as part of the picture. Currently I use a mixture of Java, .bat, bash, Ruby, Scala; some VBA for Excel. Which sometimes gets pretty ugly. I would like a cross-platform general solution with/using ,,native'' parts close to OS-specifics. Like e.g. Ruby driving some Windows-specific stuff (just a guess). What do You use? TIA

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  • Why doesn't the F# Set implement ISet<T>?

    - by Sean Devlin
    The .NET Framework is adding an ISet<T> interface with the 4.0 release. In the same release, F# is being added as a first-class language. F# provides an immutable Set<'T> class. It would seem logical to me that the immutable set provided would implement the ISet<T> interface, but it doesn't. Does anyone know why? My guess is that they didn't want to implement an interface intended to be mutable, but I don't think this explanation holds up. After all, their Map<'Key, 'Value> class implements IDictionary, which is mutable. And there are examples elsewhere in the framework of classes implementing interfaces that are only partially appropriate. My other thought is that ISet<T> is new, so maybe they didn't get around to it. But that seems kind of thin. Does the fact that ISet<T> is generic (v. IDictionary, which is not) have anything to do with it? Any thoughts on the matter would be appreciated.

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  • Persistent warning message about "initWithDelegate"!

    - by RickiG
    Hi This is not an actual Xcode error message, it is a warning that has been haunting me for a long time. I have found no way of removing it and I think I maybe have overstepped some unwritten naming convention rule. If I build a class, most often extending NSObject, whose only purpose is to do some task and report back when it has data, I often give it a convenience constructor like "initWithDelegate". The first time I did this in my current project was for a class called ISWebservice which has a protocol like this: @protocol ISWebserviceDelegate @optional - (void) serviceFailed:(NSError*) error; - (void) serviceSuccess:(NSArray*) data; @required @end Declared in my ISWebservice.h interface, right below my import statements. I have other classes that uses a convenience constructor named "initWithDelegate". E.g. "InternetConnectionLost.h", this class does not however have its methods as optional, there are no @optional @required tags in the declaration, i.e. they are all required. Now my warning pops up every time I instantiate one of these Classes with convenience constructors written later than the ISWebservice, so when utilizing the "InternetConnectionLost" class, even though the entire Class owning the "InternetConnectionLost" object has nothing to do with the "ISWebservice" Class, no imports, methods being called, no nothing, the warning goes: 'ClassOwningInternetConnectionLost' does not implement the 'ISWebserviceDelegate' protocol I does not break anything, crash at runtime or do me any harm, but it has begun to bug me as I near release. Also, because several classes use the "initWithDelegate" constructor naming, I have 18 of these warnings in my build results and I am getting uncertain if I did something wrong, being fairly new at this language. Hope someone can shed a little light on this warning, thank you:)

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  • Table valued function only returns CLR error

    - by Anthony
    I have read-only access to a database that was set up for a third-party, closed-source app. Once group of (hopefully) useful table functions only returns the error: Failed to initialize the Common Language Runtime (CLR) v2.0.50727 with HRESULT 0x80131522. You need to restart SQL server to use CLR integration features. (severity 16) But in theory, the third-party app should be able to use the function (either directly or indirectly), so I'm convinced I'm not setting things up right. I'm very new to SQL Server, so I could be missing something obvious. Or I could be missing something really slight, I have no idea. Here is an example of a query that returns the above error: SELECT * FROM dbo.UncompressDataDateRange(4,'Apr 24 2010 12:00AM','Apr 30 2010 12:00AM') Where the function takes three parameters: The Data Set (int) -- basically the data has 6 classifications, and the giant table this should be pulling from has a column to indicate which is which. startDate (smalldatetime) endDate (smalldatetime) There are other, similar functions that expand on the same idea, all returning the same error. Quick Note: I'm not sure if this is relevant, but I was able to connect to the database via SQL Studio (but without the privs to script the functions as code), and a checked the dependency for the above sample function. It turns out that it is a dependent of a view that I have gotten to work, and that view is dependent of the larger, much-hairier data-table. This makes me think I should somehow be pointing the function at the results of the view, but I'm not seeing any documentation that shows how that is done.

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  • Dynamically created operators

    - by Gero
    I created a program using dev-cpp and wxwidgets which solves a puzzle. The user must fill the operations blocks and the results blocks, and the program will solve it. Im solving it using bruteforce, i generate all non repeated 9 length number combinations using a recursive algorithm. It does it pretty fast. Up to here all is great! But the problem is when my program operates depending the character on the blocks. Its extremely slow (it never gets the answer), because of the chars comparation against +, -, *, etc. Im doing a CASE. Is there some way or some programming language wich allows dinamic creation of operators? So i can define the operator ROW1COL2 to be a +, and the same way to all other operations. I leave a screenshot of the app, so its easier to understand how the puzzle works. http://www.imageshare.web.id/images/9gg5cev8vyokp8rhlot9.png PD: The algorithm works, i tryed it with a trivial puzzle, and solved it in a second.

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  • Threads, Sockets, and Designing Low-Latency, High Concurrency Servers

    - by lazyconfabulator
    I've been thinking a lot lately about low-latency, high concurrency servers. Specifically, http servers. http servers (fast ones, anyway) can serve thousands of users simultaneously, with very little latency. So how do they do it? As near as I can tell, they all use events. Cherokee and Lighttpd use libevent. Nginx uses it's own event library performing much the same function of libevent, that is, picking a platform optimal strategy for polling events (like kqueue on *bsd, epoll on linux, /dev/poll on Solaris, etc). They all also seem to employ a strategy of multiprocess or multithread once the connection is made - using worker threads to handle the more cpu intensive tasks while another thread continues to listen and handle connections (via events). This is the extent of my understanding and ability to grok the thousand line sources of these applications. What I really want are finer details about how this all works. In examples of using events I've seen (and written) the events are handling both input and output. To this end, do the workers employ some sort of input/output queue to the event handling thread? Or are these worker threads handling their own input and output? I imagine a fixed amount of worker threads are spawned, and connections are lined up and served on demand, but how does the event thread feed these connections to the workers? I've read about FIFO queues and circular buffers, but I've yet to see any implementations to work from. Are there any? Do any use compare-and-swap instructions to avoid locking or is locking less detrimental to event polling than I think? Or have I misread the design entirely? Ultimately, I'd like to take enough away to improve some of my own event-driven network services. Bonus points to anyone providing solid implementation details (especially for stuff like low-latency queues) in C, as that's the language my network services are written in.

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  • How to use <c:out value=...> taglib

    - by artaxerxe
    I have the class A: package a; public class A { private int x = 9; public int getX() { return x; } } and the ajsp.jsp file: <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> </head> <body> <jsp:useBean id = "a" class = "a.A" /> <c:out value = "${a.x}" /> </body> </html> when i run it, it gives an error : org.apache.jasper.JasperException: /ajsp.jsp(11,0) PWC6236: According to TLD or attribute directive in tag file, attribute value does not accept any expressions if instead of <c:out value = "${a.x}" /> i use <jsp:getProperty property="x" name="a"/> it goes perfect. So, what is the problem? Thank advance.

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  • Go: using a pointer to array

    - by Sean
    I'm having a little play with google's Go language, and I've run into something which is fairly basic in C but doesn't seem to be covered in the documentation I've seen so far When I pass a pointer to an array to a function, I presumed we'd have some way to access it as follows: func conv(x []int, xlen int, h []int, hlen int, y *[]int) for i := 0; i<xlen; i++ { for j := 0; j<hlen; j++ { *y[i+j] += x[i]*h[j] } } } But the Go compiler doesn't like this: sean@spray:~/dev$ 8g broke.go broke.go:8: invalid operation: y[i + j] (index of type *[]int) Fair enough - it was just a guess. I have got a fairly straightforward workaround: func conv(x []int, xlen int, h []int, hlen int, y_ *[]int) { y := *y_ for i := 0; i<xlen; i++ { for j := 0; j<hlen; j++ { y[i+j] += x[i]*h[j] } } } But surely there's a better way. The annoying thing is that googling for info on Go isn't very useful as all sorts of C\C++\unrelated results appear for most search terms.

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  • Great examples of self-paced labs and exercises

    - by Mayo
    It is probably a safe bet that many of us are what they call Tactile / Kinesthetic Learners meaning that we learn best when we are physically doing something as opposed to listening to an online tutorial or reading a book. My goal with this question is to derive a list of books or online resources that serve as superb examples of self-paced programming labs and exercises. For example, I was extremely impressed with the SportsStore exercise in Steven Sanderson's Pro ASP.NET MVC Framework. The exercise spanned multiple chapters and gradually introduced new topics. I was also impressed with the materials associated with the Windows Azure Boot Camp. The demos and lab materials, accessible through the website, allow us to practice and reinforce what we can read about in articles and books. Please list any examples you might have, one per submission, below. The question is language/platform agnostic. Suggestions can be generic or specific to a given technology (PHP, SQL Server, Azure, Flash, Objective C, etc.). I only ask that the answers pertain to labs and exercises that relate to programming. My hope is that the best answers will float to the top allowing developers to review the top answers and find another programming topic that can be learned through example.

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  • Flex 3: should I provide prepared data to my component or make it to process data before display?

    - by grapkulec
    I'm starting to learn a little Flex just for fun and maybe to prove that I still can learn something new :) I have some idea for a project and one of its parts is a tree component which could display data in different ways depending on configuration. The idea There is list of objects having properties like id, date, time, name, description. And sometimes list should be displayed like this: first level: date second level: time third level: name and sometimes like this: first level: year second level: month third level: day fourth level: time and name By level I mean level of nesting of course. So, we can have years, that have months, that have days, that have hours and so forth. The problem What could be the best way to do it? I mean, should I prepare data for different ways of nesting outside of component or even outside of flex? I can do it at web service level in C# where I plan to have database access layer and send to flex nice and ready to display XML or array of objects. But I wonder if that won't cause additional and maybe unneccessary network traffic. I tried to hack some code in my component to convert my data objects into XML or ArrayCollection but I don't know enough of Flex and got stuck on elimination of duplicates or getting specific data by some key value. Usually to do such things I have STL with maps, sets and vectors and I find Flex arrays and even Dictionary a little bit confusing (I've read language reference and googled without any significant luck). The question So, to sum things up: should I give my tree component data prepared just for chosen type of display or should I try to do it internally inside component (or some helper class written in ActionScript)?

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  • How to get entire input string in Lex and Yacc?

    - by DevDevDev
    OK, so here is the deal. In my language I have some commands, say XYZ 3 5 GGB 8 9 HDH 8783 33 And in my Lex file XYZ { return XYZ; } GGB { return GGB; } HDH { return HDH; } [0-9]+ { yylval.ival = atoi(yytext); return NUMBER; } \n { return EOL; } In my yacc file start : commands ; commands : command | command EOL commands ; command : xyz | ggb | hdh ; xyz : XYZ NUMBER NUMBER { /* Do something with the numbers */ } ; etc. etc. etc. etc. My question is, how can I get the entire text XYZ 3 5 GGB 8 9 HDH 8783 33 Into commands while still returning the NUMBERs? Also when my Lex returns a STRING [0-9a-zA-Z]+, and I want to do verification on it's length, should I do it like rule: STRING STRING { if (strlen($1) < 5 ) /* Do some shit else error */ } or actually have a token in my Lex that returns different tokens depending on length?

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  • ASP.MVC 2 RTM + ModelState Error at Id property

    - by Zote
    I have this classes: public class GroupMetadata { [HiddenInput(DisplayValue = false)] public int Id { get; set; } [Required] public string Name { get; set; } } [MetadataType(typeof(GrupoMetadata))] public partial class Group { public virtual int Id { get; set; } public virtual string Name { get; set; } } And this action: [HttpPost] public ActionResult Edit(Group group) { if (ModelState.IsValid) { // Logic to save return RedirectToAction("Index"); } return View(group); } That's my view: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Group>" %> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <% using (Html.BeginForm()) {%> <fieldset> <%= Html.EditorForModel() %> <p> <input type="submit" value="Save" /> </p> </fieldset> <% } %> <div> <%=Html.ActionLink("Back", "Index") %> </div> </asp:Content> But ModelState is always invalid! As I can see, for MVC validation 0 is invalid, but for me is valid. How can I fix it since, I didn't put any kind of validation in Id property? UPDATE: I don't know how or why, but renaming Id, in my case to PK, solves this problem. Do you know if this an issue in my logic/configuration or is an bug or expected behavior? Thank you

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  • How do I select a row in a table based on what ddl option is selected MVC?

    - by user54197
    I have a table with a few rows of data. I would like to display a row based on what option is selected on the ddl. how do I do that? <script type="text/javascript" language="javascript"> function optionSelected() { alert('HELP!!'); } </script> ... <select id="optionSelect" onchange="optionSelected()"> <option id="1">1</option> <option id="2">2</option> <option id="3">3</option> </select> <br /> <table id="optionList"> <tr><td id="1">Option 1 Selected</td></tr> <tr><td id="2">Option 2 Selected</td></tr> <tr><td id="3">Option 3 Selected</td></tr> </table>

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  • SimpleModal -- Open OnLoad

    - by Bill Griffith
    I'm new to JQuery -- not new to javascript. Was able to open the OSX STYLE DIALOG using the hyperlink button provided in the demo index.html page, but would like to open it on the page load. I read a couple links on StackOverflow (http://stackoverflow.com/questions/1611727/how-do-i-invoke-a-simplemodal-osx-dialog-on-page-load), but still could not get it to work in the exact same index.html page. I finally resorted to a stopgap measure by programmatically invoking the button click of a hidden button element -- see following fragment: onLoad="document.getElementById('load_OSX_Example').click();"> <input type="hidden" id="load_OSX_Example" value="" class='osx'> <script type="text/javascript" language="javascript"> //#### open the OSX Modal ########## $(document).ready(function(){ $("#osx-modal-content").modal(); }); </script> So I have two questions: How can you invoke the class='osx' using javascript/html programmatically? Why won't this work using the $("#osx-modal-content").modal(); call in javascript (see fragment above)? I tried this in multiple browsers, and the only content that displayed on the screen was content of this tag: "div id="osx-modal-title", and there was no error in the jscript console.

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  • Calculate order price by date selection value

    - by albatross
    Alright, I know there's a simple way to do this, but it's been years since I've done much javascript My client has an online order form for event registration (developed by previous web dev.). Currently the order total is just a hidden field: <INPUT value=78.00 type=hidden name=amount /> But I need the total to calculate based on what date they choose: <SELECT style="BACKGROUND-COLOR: #ffff99" name=altDate1> <OPTION value=04/09> Friday, April 9 </OPTION> <OPTION value=04/14> Wednesday, April 14 </OPTION> <OPTION value=04/16> Friday, April 16 </OPTION> <OPTION value=04/19> Monday, April 19 </OPTION> <OPTION value=04/29> Thursday, April 29 </OPTION> </SELECT> This is the javascript that process the form: <SCRIPT language=Javascript> function PaymentButtonClick() { document.addform.Product_Name.value = document.Information.StudentLastName.value + ","+ document.Information.StudentFirstName.value+","+ document.Information.StudentID.value+","+ document.Information.altDate1.name+","+","+ document.Information.Guests.value+ "," + document.Information.StudentType.value; document.addform.Product_Code.value = document.Information.StudentID.value; if ((document.Information.UCheck.checked==true) && (document.Information.altDate1.value != "") && (document.Information.altDate1.value != "x")) { if (document.Information.StudentLastName.value != "" || document.Information.StudentFirstName.value != "" || document.Information.StudentID.value != "" ) { document.addform.submit(); } else { alert("Please enter missing information"); } } } </SCRIPT>

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  • Keyboard input: how to separate keycodes received from user

    - by Iulian Serbanoiu
    Hello, I am writing an application involving user input from the keyboard. For doing it I use this way of reading the input: #include <stdio.h> #include <termios.h> #include <unistd.h> int mygetch( ) { struct termios oldt, newt; int ch; tcgetattr( STDIN_FILENO, &oldt ); newt = oldt; newt.c_lflag &= ~( ICANON | ECHO ); tcsetattr( STDIN_FILENO, TCSANOW, &newt ); ch = getchar(); tcsetattr( STDIN_FILENO, TCSANOW, &oldt ); return ch; } int main(void) { int c; do{ c = mygetch(); printf("%d\n",c); }while(c!='q'); return 0; } Everyting works fine for letters digits,tabs but when hiting DEL, LEFT, CTRL+LEFT, F8 (and others) I receive not one but 3,4,5 or even 6 characters. The question is: Is is possible to make a separation of these characters (to actually know that I only hit one key or key combination). What I would like is to have a function to return a single integer value for any type of input (letter, digit, F1-F12, DEl, PGUP, PGDOWN, CTRL+A, CTRL+ALT+A, ALT+LEFT, etc). Is this possible? I'm interested in an idea to to this, the language doesn't matter much, though I'd prefer perl or c. Thanks, Iulian

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  • What is the name of this geometrical function?

    - by Spike
    In a two dimentional integer space, you have two points, A and B. This function returns an enumeration of the points in the quadrilateral subset bounded by A and B. A = {1,1} B = {2,3} Fn(A,B) = {{1,1},{1,2},{1,3},{2,1},{2,2},{2,3}} I can implement it in a few lines of LINQ. private void UnknownFunction(Point to, Point from, List<Point> list) { var vectorX = Enumerable.Range(Math.Min(to.X, from.X), Math.Abs(to.X - from.Y) + 1); var vectorY = Enumerable.Range(Math.Min(to.Y, from.Y), Math.Abs(to.Y - from.Y) + 1); foreach (var x in vectorX) foreach (var y in vectorY) list.Add(new Point(x, y)); } I'm fairly sure that this is a standard mathematical operation, but I can't think what it is. Feel free to tell me that it's one line of code in your language of choice. Or to give me a cunning implementation with lambdas or some such. But mostly I just want to know what it's called. It's driving me nuts. It feels a little like a convolution, but it's been too long since I was at school for me to be sure.

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  • Parsing basic math equations for children's educational software?

    - by Simucal
    Inspired by a recent TED talk, I want to write a small piece of educational software. The researcher created little miniature computers in the shape of blocks called "Siftables". [David Merril, inventor - with Siftables in the background.] There were many applications he used the blocks in but my favorite was when each block was a number or basic operation symbol. You could then re-arrange the blocks of numbers or operation symbols in a line, and it would display an answer on another siftable block. So, I've decided I wanted to implemented a software version of "Math Siftables" on a limited scale as my final project for a CS course I'm taking. What is the generally accepted way for parsing and interpreting a string of math expressions, and if they are valid, perform the operation? Is this a case where I should implement a full parser/lexer? I would imagine interpreting basic math expressions would be a semi-common problem in computer science so I'm looking for the right way to approach this. For example, if my Math Siftable blocks where arranged like: [1] [+] [2] This would be a valid sequence and I would perform the necessary operation to arrive at "3". However, if the child were to drag several operation blocks together such as: [2] [\] [\] [5] It would obviously be invalid. Ultimately, I want to be able to parse and interpret any number of chains of operations with the blocks that the user can drag together. Can anyone explain to me or point me to resources for parsing basic math expressions? I'd prefer as much of a language agnostic answer as possible.

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  • Problem executing script using Python and subprocces.call yet works in Bash

    - by Antoine Benkemoun
    Hello, For the first time, I am asking a little bit of help over here as I am more of a ServerFault person. I am doing some scripting in Python and I've been loving the language so far yet I have this little problem which is keeping my script from working. Here is the code line in question : subprocess.call('xen-create-image --hostname '+nom+' --memory '+memory+' --partitions=/root/scripts/part.tmp --ip '+ip+' --netmask '+netmask+' --gateway '+gateway+' --passwd',shell=True) I have tried the same thing with os.popen. All the variables are correctly set. When I execute the command in question in my regular Linux shell, it works perfectly fine but when I execute it using my Python scripts, I get bizarre errors. I even replaced subprocess.call() by the print function to make sure I am using the exact output of the command. I went looking into environment variables of my shell but they are pretty much the same... I'll post the error I am getting but I'm not sure it's relevant to my problem. Use of uninitialized value $lines[0] in substitution (s///) at /usr/share/perl5/Config/IniFiles.pm line 614. Use of uninitialized value $_ in pattern match (m//) at /usr/share/perl5/Config/IniFiles.pm line 628. I am not a Python expert so I'm most likely missing something here. Thank you in advance for your help, Antoine

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  • "Pattern matching" of algebraic type data constructors

    - by jetxee
    Let's consider a data type with many constructors: data T = Alpha Int | Beta Int | Gamma Int Int | Delta Int I want to write a function to check if two values are produced with the same constructor: sameK (Alpha _) (Alpha _) = True sameK (Beta _) (Beta _) = True sameK (Gamma _ _) (Gamma _ _) = True sameK _ _ = False Maintaining sameK is not much fun, it is potentially buggy. For example, when new constructors are added to T, it's easy to forget to update sameK. I omitted one line to give an example: -- it’s easy to forget: -- sameK (Delta _) (Delta _) = True The question is how to avoid boilerplate in sameK? Or how to make sure it checks for all T constructors? The workaround I found is to use separate data types for each of the constructors, deriving Data.Typeable, and declaring a common type class, but I don't like this solution, because it is much less readable and otherwise just a simple algebraic type works for me: {-# LANGUAGE DeriveDataTypeable #-} import Data.Typeable class Tlike t where value :: t -> t value = id data Alpha = Alpha Int deriving Typeable data Beta = Beta Int deriving Typeable data Gamma = Gamma Int Int deriving Typeable data Delta = Delta Int deriving Typeable instance Tlike Alpha instance Tlike Beta instance Tlike Gamma instance Tlike Delta sameK :: (Tlike t, Typeable t, Tlike t', Typeable t') => t -> t' -> Bool sameK a b = typeOf a == typeOf b

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  • Normalize whitespace and other plain-text formatting routines

    - by dreftymac
    Background: The language is JavaScript. The goal is to find a library or pre-existing code to do low-level plain-text formatting. I can write it myself, but why re-invent the wheel. The issue is: it is tough to determine if a "wheel" is out there, since any search for JavaScript libraries pulls up an ocean of HTML-centric stuff. I am not interested in HTML necessarily, just text. Example: I need a JavaScript function that changes this: BEFORE: nisi ut aliquip | ex ea commodo consequat duis |aute irure dolor in esse cillum dolore | eu fugiat nulla pariatur |excepteur sint occa in culpa qui | officia deserunt mollit anim id |est laborum ... into this ... AFTER: nisi ut aliquip | ex ea commodo consequat duis | aute irure dolor in esse cillum dolore | eu fugiat nulla pariatur | excepteur sint occa in culpa qui | officia deserunt mollit anim id | est laborum Question: Does it exist, a JavaScript library that is non-html-web-development-centric that has functions for normalizing spaces in delimited plain text, justifying and spacing plain text? Rationale: Investigating JavaScript for use in a programmer's text editor.

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