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• How to convert many thousands of lines of VBScript to C#?

  - by Ross Patterson

  I have a collection of about 10,000 small VBScript programs (50-100 lines each) and a small collection of larger ones, and I'm looking for a way to convert them to C# without resorting to by-hand transliteration. The programs are automated test cases for a web application, written for HP/Mercury's QuickTest Pro, and I'm trying to turn them into test cases for Selenium. Luckily, the tests appear to be well-written, using a library of building blocks and idioms (the larger programs), so the test cases actually resemble a domain-specific language more than they do VBScript, and the QTP-ness is well-buried inside the libraries. Ideally, what I'm searching for is a tool that can do the syntactic transformation from VBScript to C# for both the dsl-ish test cases and also the more complicated building-block libraries. That would leave me with a manual cleanup of the libraries, and probably very little work on the test cases. If I could find a VBScript-to-VB.NET translator, I'd take that also, as I suspect I could compile the VB.NET and then de-compile to C# using .NET Relector or something similar. Plan B is to write a translator of my own for the test cases, since they're in a very straight-line style, but it wouldn't help with the libraries. Any suyggestions? I haven't written a compiler in at least 15 years, and while I haven't forgotten how, I'm not looking forward to it - least of all for VBScript!

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• Is this a bug in plist or Xcode?

  - by Pedro

  G'day All If you create a date item in the plist editor of Xcode or Apple's standalone plist editor you get something of the form <date>2010-05-29T10:30:00Z</date> which is a nice well formed ISO date at UTC (indicated by the "Z"). Because I'm in timezone UTC +10 when that's read into my app & then displayed I get 8:30 PM out, still good. However if that is a time in my timezone it should be <date>2010-05-29T10:30:00+10</date> (replacing "Z" with my timezone offset). All of my attempts at reading such dates into my iPhone app have had the plist rejected as if it is malformed & editing a plist with such a date in Apple's editors changed the "+10" to "Z" without adjusting the time. Do others think I'm correct in thinking this is a bug in either plist or Xcode? My feeling is that the implementation of ISO date & time in plist is incomplete. Cheers, Pedro :)

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• Rails: generating URLs for actions in JSON response

  - by Chris Butler

  In a view I am generating an HTML canvas of figures based on model data in an app. In the view I am preloading JSON model data in the page like this (to avoid an initial request back): <script type="text/javascript" charset="utf-8"> <% ActiveRecord::Base.include_root_in_json = false -%> var objects = <%= @objects.to_json(:include => :other_objects) %>; ... Based on mouse (or touch) interaction I want to redirect to other parts of my app that are model specific (such as view, edit, delete, etc.). Rather than hard code the URLs in my JavaScript I want to generate them from Rails (which means it always adapts the latest routes). It seems like I have one of three options: Add an empty attr to the model that the controller fills in with the appropriate URL (we don't want to use routes in the model) before the JSON is generated Generate custom JSON where I add the different URLs manually Generate the URL as a template from Rails and replace the IDs in JavaScript as appropriate I am starting to lean towards #1 for ease of implementation and maintainability. Are there any other options that I am missing? Is #1 not the best? Thanks! Chris

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• Is Stream.Write thread-safe?

  - by Mike Spross

  I'm working on a client/server library for a legacy RPC implementation and was running into issues where the client would sometimes hang when waiting to a receive a response message to an RPC request message. It turns out the real problem was in my message framing code (I wasn't handling message boundaries correctly when reading data off the underlying NetworkStream), but it also made me suspicious of the code I was using to send data across the network, specifically in the case where the RPC server sends a large amount of data to a client as the result of a client RPC request. My send code uses a BinaryWriter to write a complete "message" to the underlying NetworkStream. The RPC protocol also implements a heartbeat algorithm, where the RPC server sends out PING messages every 15 seconds. The pings are sent out by a separate thread, so, at least in theory, a ping can be sent while the server is in the middle of streaming a large response back to a client. Suppose I have a Send method as follows, where stream is a NetworkStream: public void Send(Message message) { //Write the message to a temporary stream so we can send it all-at-once MemoryStream tempStream = new MemoryStream(); message.WriteToStream(tempStream); //Write the serialized message to the stream. //The BinaryWriter is a little redundant in this //simplified example, but here because //the production code uses it. byte[] data = tempStream.ToArray(); BinaryWriter bw = new BinaryWriter(stream); bw.Write(data, 0, data.Length); bw.Flush(); } So the question I have is, is the call to bw.Write (and by implication the call to the underlying Stream's Write method) atomic? That is, if a lengthy Write is still in progress on the sending thread, and the heartbeat thread kicks in and sends a PING message, will that thread block until the original Write call finishes, or do I have to add explicit synchronization to the Send method to prevent the two Send calls from clobbering the stream?

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• Ruby on Rails Associations

  - by Eef

  Hey all, I am starting to create my sites in Ruby on Rails these days instead of PHP. I have picked up the language easily but still not 100% confident with associations :) I have this situation: User Model has_and_belongs_to_many :roles Roles Model has_and_belongs_to_many :users Journal Model has_and_belongs_to_many :roles So I have a roles_users table and a journals_roles table I can access the user roles like so: user = User.find(1) User.roles This gives me the roles assigned to the user, I can then access the journal model like so: journals = user.roles.first.journals This gets me the journals associated with the user based on the roles. I want to be able to access the journals like so user.journals In my user model I have tried this: def journals self.roles.collect { |role| role.journals }.flatten end This gets me the journals in a flatten array but unfortunately I am unable to access anything associated with journals in this case, e.g in the journals model it has: has_many :items When I try to access user.journals.items it does not work as it is a flatten array which I am trying to access the has_many association. Is it possible to get the user.journals another way other than the way I have shown above with the collect method? Hope you guys understand what I mean, if not let me know and ill try to explain it better. Cheers Eef

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• What should I do if i have a factory method which requires different parameters for different implem

  - by Sam Holder

  I have an interface, IMessage and a class which have several methods for creating different types of message like so: class MessageService { IMessage TypeAMessage(param 1, param 2) IMessage TypeBMessage(param 1, param 2, param 3, param 4) IMessage TypeCMessage(param 1, param 2, param 3) IMessage TypeDMessage(param 1) } I don't want this class to do all the work for creating these messages so it simply delegates to a MessageCreatorFactory which produces an IMessageCreator depending on the type given (an enumeration based on the type of the message TypeA, TypeB, TypeC etc) interface IMessageCreator { IMessage Create(MessageParams params); } So I have 4 implementations of IMessageCreator: TypeAMessageCreator, TypeBMessageCreator, TypeCMessageCreator, TypeDMessageCreator I ok with this except for the fact that because each type requires different parameters I have had to create a MessageParams object which contains 4 properties for the 4 different params, but only some of them are used in each IMessageCreator. Is there an alternative to this? One other thought I had was to have a param array as the parameter in the Create emthod, but this seems even worse as you don't have any idea what the params are. Or to create several overloads of Create in the interface and have some of them throw an exception if they are not suitable for that particular implementation (ie you called a method which needs more params, so you should have called one of the other overloads.) Does this seem ok? Is there a better solution?

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• Cross-Platform Camera API

  - by Karim

  Hi, I'm now building a video transforming filter that have to transform video frames in real-time. One of the key requirements of the filter is to have high performance to minimize the number of dropped frames during the transform. Another requirement that is of lower priority but also nice to have is to make it cross-platform (both PC's and Mobile devices). The application is built in C++. Now my question is: is there any API that is more portable and has a similar or better performance characteristics than DirectShow? as DirectShow's portability is only limited to Windows-based devices (PCs and Windows Mobile&CE platforms). Also I've notices that for example using HTC's custom camera API has far better performance than what DirectShow offers. If you want to check this, try to build a filter in DirectShow that will multiply each color by 2 and render that in real-time from camera on the screen. Then do the same with HTC's API. There is almost 4-5x performance boost with vendor's specific API. So it'd be very nice if the library used the device-specific implementation of the driver, as performance is critical when doing this transforms on a mobile device (which is about ~500 MHz).

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• iPhone: Using dispatch_after to mimick NSTimer

  - by Joseph Tura

  Don't know a whole lot about blocks. How would you go about mimicking a repeating NSTimer with dispatch_after? My problem is that I want to "pause" a timer when the app moves to the background, but subclassing NSTimer does not seem to work. I tried something which seems to work. I cannot judge its performance implications or whether it could be greatly optimized. Any input is welcome. #import "TimerWithPause.h" @implementation TimerWithPause @synthesize timeInterval; @synthesize userInfo; @synthesize invalid; @synthesize invocation; + (TimerWithPause *)scheduledTimerWithTimeInterval:(NSTimeInterval)aTimeInterval target:(id)aTarget selector:(SEL)aSelector userInfo:(id)aUserInfo repeats:(BOOL)aTimerRepeats { TimerWithPause *timer = [[[TimerWithPause alloc] init] autorelease]; timer.timeInterval = aTimeInterval; NSMethodSignature *signature = [[aTarget class] instanceMethodSignatureForSelector:aSelector]; NSInvocation *aInvocation = [NSInvocation invocationWithMethodSignature:signature]; [aInvocation setSelector:aSelector]; [aInvocation setTarget:aTarget]; [aInvocation setArgument:&timer atIndex:2]; timer.invocation = aInvocation; timer.userInfo = aUserInfo; if (!aTimerRepeats) { timer.invalid = YES; } [timer fireAfterDelay]; return timer; } - (void)fireAfterDelay { dispatch_time_t delay = dispatch_time(DISPATCH_TIME_NOW, self.timeInterval * NSEC_PER_SEC); dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_after(delay, queue, ^{ [invocation performSelectorOnMainThread:@selector(invoke) withObject:nil waitUntilDone:NO]; if (!invalid) { [self fireAfterDelay]; } }); } - (void)invalidate { invalid = YES; [invocation release]; invocation = nil; [userInfo release]; userInfo = nil; } - (void)dealloc { [self invalidate]; [super dealloc]; } @end

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• How to reference using Entity Framework and Asp.Net Mvc 2

  - by Picflight

  Tables CREATE TABLE [dbo].[Users]( [UserId] [int] IDENTITY(1,1) NOT NULL, [UserName] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL, [Email] [varchar](255) COLLATE SQL_Latin1_General_CP1_CI_AS NULL, [BirthDate] [smalldatetime] NULL, [CountryId] [int] NULL, CONSTRAINT [PK_Users] PRIMARY KEY CLUSTERED ([UserId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[TeamMember]( [UserId] [int] NOT NULL, [TeamMemberUserId] [int] NOT NULL, [CreateDate] [smalldatetime] NOT NULL CONSTRAINT [DF_TeamMember_CreateDate] DEFAULT (getdate()), CONSTRAINT [PK_TeamMember] PRIMARY KEY CLUSTERED ([UserId] ASC, [TeamMemberUserId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] dbo.TeamMember has both UserId and TeamMemberUserId as the index key. My goal is to show a list of Users on my View. In the list I want to flag, or highlight the Users that are Team Members of the LoggedIn user. My ViewModel public class UserViewModel { public int UserId { get; private set; } public string UserName { get; private set; } public bool HighLight { get; private set; } public UserViewModel(Users users, bool highlight) { this.UserId = users.UserId; this.UserName = users.UserName; this.HighLight = highlight; } } View <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MvcPaging.IPagedList<MyProject.Mvc.Models.UserViewModel>>" %> <% foreach (var item in Model) { %> <%= item.UserId %> <%= item.UserName %> <%if (item.HighLight) { %> Team Member <% } else { %> Not Team Member <% } %> How do I toggle the TeamMember or Not If I add dbo.TeamMember to the EDM, there are no relationships on this table, how will I wire it to Users object? So I am comparing the LoggedIn UserId with this list(SELECT TeamMemberUserId FROM TeamMember WHERE UserId = @LoggedInUserId)

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• WCF REST adding data using POST or PUT 400 Bad Request

  - by user55474

  HI How do i add data using wcf rest architecture. I dont want to use the channelfactory to call my method. Something similar to the webrequest and webresponse used for GET. Something similar to the ajax WebServiceProxy restInvoke Or do i always have to use the Webchannelfactory implementation I am getting a 400 BAD request by using the following Dim url As String = "http://localhost:4475/Service.svc/Entity/Add" Dim req As WebRequest = WebRequest.Create(url) req.Method = "POST" req.ContentType = "application/xml; charset=utf-8" req.Timeout = 30000 req.Headers.Add("SOAPAction", url) Dim xEle As XElement xEle = <Entity xmlns:i="http://www.w3.org/2001/XMLSchema-instance"> <Name>Entity1</Name> </Entity> Dim sXML As String = xEle .Value req.ContentLength = sXML.Length Dim sw As New System.IO.StreamWriter(req.GetRequestStream()) sw.Write(sXML) sw.Close() Dim res as HttpWebResponse = req.GetResponse() Sercice Contract is as follows <OperationContract()> _ <WebInvoke(Method:="PUT", UriTemplate:="Entity/Add")> _ Function AddEntity(ByVal e1 As Entity) DataContract is as follows <Serializable()> _ <DataContract()> _ Public Class Entity private m_Name as String <DataMember()> _ Public Property Name() As String Get Return m_Name End Get Set(ByVal value As String) m_Name = value End Set End Property End Class thanks

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• asp.net jquery how to use Plugin/Validation with web content

  - by Eyla

  I have a asp.net web content from that have a asp.net textbox and I want to use Plugin/Validation but it is not working with me here is my code: <%@ Page Title="" Language="C#" MasterPageFile="~/Master.Master" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="IMAM_APPLICATION.WebForm1" %> <%@ Register assembly="AjaxControlToolkit" namespace="AjaxControlToolkit" tagprefix="asp" %> <asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server"> <script src="js/jquery-1.4.1.js" type="text/javascript"></script> <script src="js/jquery.validate.js" type="text/javascript"></script> <script type="text/javascript"> $(document).ready(function() { $.validator.addMethod("#<%=TextBox1.ClientID %>", function(value, element) { return this.optional(element) || /^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,16}$/i.test(value); }, "Passwords are 8-16 characters with uppercase letters, lowercase letters and at least one number."); }); </script> </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server"> </asp:Content> <asp:Content ID="Content3" ContentPlaceHolderID="ContentPlaceHolder2" runat="server"> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> </asp:Content>

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• What Do You Need To Write Your Own Blog Engine?

  - by deworde

  I've been messing around with basic websites for a few years, using companies like www.Fasthosts.co.uk to do my web hosting. But I'd like to expand my skills from C++ and Java app programming into Web-based programming, and I think the best way to do that is with a project. I've chosen to go with a blog engine because it's a relative comprehensive yet non-complex project. I'm aware that you can just go to Blogger and bam! One blog. I've done that, so that I can at least have some content, and work out what I want to do with this blog. At the moment, I'm thinking I'll use it to chart my progress creating the blogging engine. But I have some questions. Do you need to be running your own server? Or is it more sensible in the short-term to use a hosting company? What types of language are worth considering? What's important to focus on from a design perspective? What unexpected problems might I encounter?

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• Concise C# code for gathering several properties with a non-null value into a collection?

  - by stakx

  A fairly basic problem for a change. Given a class such as this: public class X { public T A; public T B; public T C; ... // (other fields, properties, and methods are not of interest here) } I am looking for a concise way to code a method that will return all A, B, C, ... that are not null in an enumerable collection. (Assume that declaring these fields as an array is not an option.) public IEnumerable<T> GetAllNonNullAs(this X x) { // ? } The obvious implementation of this method would be: public IEnumerable<T> GetAllNonNullAs(this X x) { var resultSet = new List<T>(); if (x.A != null) resultSet.Add(x.A); if (x.B != null) resultSet.Add(x.B); if (x.C != null) resultSet.Add(x.C); ... return resultSet; } What's bothering me here in particular is that the code looks verbose and repetitive, and that I don't know the initial List capacity in advance. It's my hope that there is a more clever way, probably something involving the ?? operator? Any ideas?

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• Safe and polymorphic toEnum

  - by jetxee

  I'd like to write a safe version of toEnum: safeToEnum :: (Enum t, Bounded t) => Int -> Maybe t A naive implementation: safeToEnum :: (Enum t, Bounded t) => Int -> Maybe t safeToEnum i = if (i >= fromEnum (minBound :: t)) && (i <= fromEnum (maxBound :: t)) then Just . toEnum $ i else Nothing main = do print $ (safeToEnum 1 :: Maybe Bool) print $ (safeToEnum 2 :: Maybe Bool) And it doesn't work: safeToEnum.hs:3:21: Could not deduce (Bounded t1) from the context () arising from a use of `minBound' at safeToEnum.hs:3:21-28 Possible fix: add (Bounded t1) to the context of an expression type signature In the first argument of `fromEnum', namely `(minBound :: t)' In the second argument of `(>=)', namely `fromEnum (minBound :: t)' In the first argument of `(&&)', namely `(i >= fromEnum (minBound :: t))' safeToEnum.hs:3:56: Could not deduce (Bounded t1) from the context () arising from a use of `maxBound' at safeToEnum.hs:3:56-63 Possible fix: add (Bounded t1) to the context of an expression type signature In the first argument of `fromEnum', namely `(maxBound :: t)' In the second argument of `(<=)', namely `fromEnum (maxBound :: t)' In the second argument of `(&&)', namely `(i <= fromEnum (maxBound :: t))' As well as I understand the message, the compiler does not recognize that minBound and maxBound should produce exactly the same type as in the result type of safeToEnum inspite of the explicit type declaration (:: t). Any idea how to fix it?

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• Using C code in c#

  - by karthik

  When i googled to find the way to change the window style i could find the code in "C" language How can i use the snippet below in my c# application, so that i can hide the Title Bar of external application ? I have not used "C" before.. //Finds a window by class name [DllImport("USER32.DLL")] public static extern IntPtr FindWindow(string lpClassName, string lpWindowName); //Sets a window to be a child window of another window [DllImport("USER32.DLL")] public static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent); //Sets window attributes [DllImport("USER32.DLL")] public static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong); //Gets window attributes [DllImport("USER32.DLL")] public static extern int GetWindowLong(IntPtr hWnd, int nIndex); //assorted constants needed public static int GWL_STYLE = -16; public static int WS_CHILD = 0x40000000; //child window public static int WS_BORDER = 0x00800000; //window with border public static int WS_DLGFRAME = 0x00400000; //window with double border but no title public static int WS_CAPTION= WS_BORDER | WS_DLGFRAME; //window with a title bar /* This function sets the parent of the window with class ClassClass to the form/control the method is in. */ public void Reparent() { //get handle of parent form (.net property) IntPtr par = this.Handle; //get handle of child form (win32) IntPtr child = FindWindow("ClassClass", null); //set parent of child form SetParent(child, par); //get current window style of child form int style = GetWindowLong(child, GWL_STYLE); //take current window style and remove WS_CAPTION from it SetWindowLong(child, GWL_STYLE, (style & ~WS_CAPTION)); }

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• The new operator in C# isn't overriding base class member

  - by Dominic Zukiewicz

  I am confused as to why the new operator isn't working as I expected it to. Note: All classes below are defined in the same namespace, and in the same file. This class allows you to prefix any content written to the console with some provided text. public class ConsoleWriter { private string prefix; public ConsoleWriter(string prefix) { this.prefix = prefix; } public void Write(string text) { Console.WriteLine(String.Concat(prefix,text)); } } Here is a base class: public class BaseClass { protected static ConsoleWriter consoleWriter = new ConsoleWriter(""); public static void Write(string text) { consoleWriter.Write(text); } } Here is an implemented class: public class NewClass : BaseClass { protected new static ConsoleWriter consoleWriter = new ConsoleWriter("> "); } Now here's the code to execute this: class Program { static void Main(string[] args) { BaseClass.Write("Hello World!"); NewClass.Write("Hello World!"); Console.Read(); } } So I would expect the output to be Hello World! > Hello World! But the output is Hello World Hello World I do not understand why this is happening. Here is my thought process as to what is happening: The CLR calls the BaseClass.Write() method The CLR initialises the BaseClass.consoleWriter member. The method is called and executed with the BaseClass.consoleWriter variable Then The CLR calls the NewClass.Write() The CLR initialises the NewClass.consoleWriter object. The CLR sees that the implementation lies in BaseClass, but the method is inherited through The CLR executes the method locally (in NewClass) using the NewClass.consoleWriter variable I thought this is how the inheritance structure works? Please can someone help me understand why this is not working?

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• questions on nfa and dfa..

  - by Loop

  Hi Guys... Hope you help me with this one.... I have a main question which is ''how to judge whether a regular expression will be accepted by NFA and/or DFA? For eg. My question says that which of the regular expressions are equivalent? explain... 1.(a+b)*b(a+b)*b(a+b)* 2.a*ba*ba* 3.a*ba*b(a+b)* do we have to draw the NFA and DFA and then find through minimisation algorithm? if we do then how do we come to know that which regular expression is accepted by NFA/DFA so that we can begin with the answer? its so confusing.... Second is a very similar one, the question asks me to show that the language (a^nb^n|n1} is not accepted by DFA...grrrrr...how do i know this? (BTW this is a set of all strings of where a number of a's is followed by the same number of b's).... I hope I explained clearly well....

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• Mercurial repository usage with binary files for building setup files

  - by Ryan

  I have an existing Mercurial repository for a C++ application in a small corporate environment. I asked a co-worker to add the setup script to the repository and he added all of the dependency binaries, PDFs, and executable to the repository under an Install directory. I dislike having the binaries and dependencies in the same repository, but I'd like recommendations on best practices. Here are the options I am considering: Create a separate repository for the Installer and related files Create a subrepository for the Installer and related files Use a (yet to be identified) build dependency manager I am concerned with using a subrepository with Mercurial based on what I've read so far and the (apparently) incomplete implementation. I would like to get a project dependency system, e.g. Ivy, but I don't know all of the options and haven't had time yet to try out any options. I thought I'd use TortoiseHg as a basis, and it does not have the TortoiseHg binaries in the repository although it does have some binaries such as kdiff3.exe. Instead it uses setup.py to clone multiple repositories and build the apps. This seems reasonable for OSS, but not so much for corporate environments. Recommendations?

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• A "smart" (forgiving) date parser?

  - by jdmuys

  I have to migrate a very large dataset from one system to another. One of the "source" column contains a date but is really a string with no constraint, while the destination system mandates a date in the format yyyy-mm-dd. Many, but not all, of the source dates are formatted as yyyymmdd. So to coerce them to the expected format, I do (in Perl): return "$1-$2-$3" if ($val =~ /(\d{4})[-\/]*(\d{2})[-\/]*(\d{2})/); The problem arises when the source dates moves away from the "generic" yyyymmdd. The goal is to salvage as many dates as possible, before giving up. Example source strings include: 21/3/1998, March 2004, 2001, 3/4/97 I can try to match as many of the examples I can find with a succession of regular expressions such as the one above. But is there something smarter to do? Am I not reinventing the wheel? Is there a library somewhere doing something similar? I couldn't find anything relevant googling "forgiving date parser". (any language is OK).

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• Fastest inline-assembly spinlock

  - by sigvardsen

  I'm writing a multithreaded application in c++, where performance is critical. I need to use a lot of locking while copying small structures between threads, for this I have chosen to use spinlocks. I have done some research and speed testing on this and I found that most implementations are roughly equally fast: Microsofts CRITICAL_SECTION, with SpinCount set to 1000, scores about 140 time units Implementing this algorithm with Microsofts InterlockedCompareExchange scores about 95 time units Ive also tried to use some inline assembly with __asm {} using something like this code and it scores about 70 time units, but I am not sure that a proper memory barrier has been created. Edit: The times given here are the time it takes for 2 threads to lock and unlock the spinlock 1,000,000 times. I know this isn't a lot of difference but as a spinlock is a heavily used object, one would think that programmers would have agreed on the fastest possible way to make a spinlock. Googling it leads to many different approaches however. I would think this aforementioned method would be the fastest if implemented using inline assembly and using the instruction CMPXCHG8B instead of comparing 32bit registers. Furthermore memory barriers must be taken into account, this could be done by LOCK CMPXHG8B (I think?), which guarantees "exclusive rights" to the shared memory between cores. At last [some suggests] that for busy waits should be accompanied by NOP:REP that would enable Hyper-threading processors to switch to another thread, but I am not sure whether this is true or not? From my performance-test of different spinlocks, it is seen that there is not much difference, but for purely academic purpose I would like to know which one is fastest. However as I have extremely limited experience in the assembly-language and with memory barriers, I would be happy if someone could write the assembly code for the last example I provided with LOCK CMPXCHG8B and proper memory barriers in the following template: __asm { spin_lock: ;locking code. spin_unlock: ;unlocking code. }

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• How do I ensure that a regex does not match an empty string?

  - by Dancrumb

  I'm using the Jison parser generator for Javascript and am having problems with my language specification. The program I'm writing will be a calculator that can handle feet, inches and sixteenths. In order to do this, I have the following specification: %% ([0-9]+\s*"'")?\s*([0-9]+\s*"\"")?\s*([0-9]+\s*"s")? {return 'FIS';} [0-9]+("."[0-9]+)?\b {return 'NUMBER';} \s+ {/* skip whitespace */} "*" {return '*';} "/" {return '/';} "-" {return '-';} "+" {return '+';} "(" {return '(';} ")" {return ')';} <<EOF>> {return 'EOF';} Most of these lines come from a basic calculator specification. I simply added the first line. The regex correctly matches feet, inch, sixteenths, such as 6'4" (six feet, 4 inches) or 4"5s (4 inches, 5 sixteenths) with any kind of whitespace between the numbers and indicators. The problem is that the regex also matches a null string. As a result, the lexical analysis always records a FIS at the start of the line and then the parsing fails. Here is my question: is there a way to modify this regex to guarantee that it will only match a non-zero length string?

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• creating matrix with probabilities

  - by John Chan

  Hi all, I want to generate a matrix of NxN to test some code that I have where each row contains floats as the elements and has to add up to 1 (i.e. a row with a set of probabilities). Where it gets tricky is that I want to make sure that randomly some of the elements should be 0 (in fact most of the elements should be 0 except for some random ones to be the probabilities). I need the probabilities to be 1/m where m is the number of elements that are not 0 within a single row. I tried to think of ways to output this, but essentially I would need this stored in a C++ array. So even if I output to a file I would still have the issue of not having it in array as I need it. At the end of it all I need that array because I want to generate a Market Matrix file. I found an implementation in C++ to take an array and convert it to the market matrix file, so this is what I am basing my findings on. My input for the rest of the code takes in this market matrix file so I need that to be the primary form of output. The language does not matter, I just want to generate the file at the end (I found a way mmwrite and mmread in python as well) Please help, I am stuck and not really sure how to implement this.

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• Python, Ruby, and C#: Use cases?

  - by thaorius

  Hi everyone. For as long as I can remember, I've always had a "favorite" language, which I use for most projects, until, for some particular reason, there is no way/point on using it for project XYZ. At that point, I find myself rusty (and sometimes outdated) on other languages+libraries+toolchains. So I decided, I would just use some languages/libs/tools for some things, and some for other, effectively keeping them fresh (there would obviously be exceptions, I'm not looking for an arbitrary rule set, but some guidelines). I wanted an opinion on what would be your standard use cases (new projects) for Python, Ruby, and C# (Mono). At the moment, I have time like this:Languages: C#: Mid-Large Sized Projects (mainly server-side daemons) High Performance (I hardly ever need C's performance, but Python just doesn't cut it) Relatively Low Footprint (vs the JVM, for example) Ruby: Web Applications Python: General Use Scripts (automation, system config, etc) Small-Mid Sized Projects Prototyping Web Applications About Ruby, I have no idea what to use it for that I can't use Python for (specially considering Python is more easily found installed by default). And I like both languages (though I'm really new to Ruby), which makes things even worse. As for C#, I have not used a Windows powered computer in a few years, I don't make things for Windows computers, and I don't mind waiting for Mono to implement some new features. That being said, I haven't found many people on the internet using it for server-sided *nix programming (not web related). I would appreciate some insight on this too. Thanks for your time.

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• Easiest way to plot values as symbols in scatter plot?

  - by AllenH

  In an answer to an earlier question of mine regarding fixing the colorspace for scatter images of 4D data, Tom10 suggested plotting values as symbols in order to double-check my data. An excellent idea. I've run some similar demos in the past, but I can't for the life of me find the demo I remember being quite simple. So, what's the easiest way to plot numerical values as the symbol in a scatter plot instead of 'o' for example? Tom10 suggested plt.txt(x,y,value)- and that is the implementation used in a number of examples. I however wonder if there's an easy way to evaluate "value" from my array of numbers? Can one simply say: str(valuearray) ? Do you need a loop to evaluate the values for plotting as suggested in the matplotlib demo section for 3D text scatter plots? Their example produces: However, they're doing something fairly complex in evaluating the locations as well as changing text direction based on data. So, is there a cute way to plot x,y,C data (where C is a value often taken as the color in the plot data- but instead I wish to make the symbol)? Again, I think we have a fair answer to this- I just wonder if there's an easier way?

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• Question about cloning in Java

  - by devoured elysium

  In Effective Java, the author states that: If a class implements Cloneable, Object's clone method returns a field-by-field copy of the object; otherwise it throws CloneNotSupportedException. What I'd like to know is what he means with field-by-field copy. Does it mean that if the class has X bytes in memory, it will just copy that piece of memory? If yes, then can I assume all value types of the original class will be copied to the new object? class Point { private int x; private int y; @Override public Point clone() { return (Point)super.clone(); } } If what Object.clone() does is a field by field copy of the Point class, I'd say that I wouldn't need to explicitly copy fields x and y, being that the code shown above will be more than enough to make a clone of the Point class. That is, the following bit of code is redundant: @Override public Point clone() { Point newObj = (Point)super.clone(); newObj.x = this.x; //redundant newObj.y = this.y; //redundant } Am I right? I know references of the cloned object will point automatically to where the original object's references pointed to, I'm just not sure what happens specifically with value types. If anyone could state clearly what Object.clone()'s algorithm specification is (in easy language) that'd be great. Thanks

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