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  • C#/Java: Proper Implementation of CompareTo when Equals tests reference identity

    - by Paul A Jungwirth
    I believe this question applies equally well to C# as to Java, because both require that {c,C}ompareTo be consistent with {e,E}quals: Suppose I want my equals() method to be the same as a reference check, i.e.: public bool equals(Object o) { return this == o; } In that case, how do I implement compareTo(Object o) (or its generic equivalent)? Part of it is easy, but I'm not sure about the other part: public int compareTo(Object o) { if (! (o instanceof MyClass)) return false; MyClass other = (MyClass)o; if (this == other) { return 0; } else { int c = foo.CompareTo(other.foo) if (c == 0) { // what here? } else { return c; } } } I can't just blindly return 1 or -1, because the solution should adhere to the normal requirements of compareTo. I can check all the instance fields, but if they are all equal, I'd still like compareTo to return a value other than 0. It should be true that a.compareTo(b) == -(b.compareTo(a)), and the ordering should stay consistent as long as the objects' state doesn't change. I don't care about ordering across invocations of the virtual machine, however. This makes me think that I could use something like memory address, if I could get at it. Then again, maybe that won't work, because the Garbage Collector could decide to move my objects around. hashCode is another idea, but I'd like something that will be always unique, not just mostly unique. Any ideas?

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  • Writing a JMS Publisher without "public static void main"

    - by The Elite Gentleman
    Hi guys, Every example I've seen on the web, e.g. http://www.codeproject.com/KB/docview/jms_to_jms_bridge_activem.aspx, creates a publisher and subscriber with a public static void main method. I don't think that'll work for my web application. I'm learning JMS and I've setup Apache ActiveMQ to run on JBoss 5 and Tomcat 6 (with no glitches). I'm writing a messaging JMS service that needs to send email asynchronously. I've already written a JMS subscriber that receives the message (the class inherits MessageListener). My question is simple: How do I write a publisher that will so that my web applications can call it? Does it have to be published somewhere? My thought is to create a publisher with a no-attribute constructor (in there) and get the MessageQueue Factory, etc. from the JNDI pool (in the constructor). Is my idea correct? How do I subscribe my subscriber to the Queue Receiver? (So far, the subscriber has no constructor, and if I write a constructor, do I always subscribe myself to the Queue receiver?) Thanks for your help, sorry if my terminology is not up to scratch, there are too many java terminologies that I get lost sometimes (maybe a java GPS will do! :-) ) PS Is there a tutorial out there that explains how to write a "better" (better can mean anything, but in my case it's all about performance in high demand requests) JMS Publisher and Subscriber that I can run on Application Server such as JBoss or Glassfish? Don't forget that the JMS application will needs a "guarantee" uptime as many applications will use this.

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  • Find max integer size that a floating point type can handle without loss of precision

    - by Checkers
    Double has range more than a 64-bit integer, but its precision is less dues to its representation (since double is 64-bit as well, it can't fit more actual values). So, when representing larger integers, you start to lose precision in the integer part. #include <boost/cstdint.hpp> #include <limits> template<typename T, typename TFloat> void maxint_to_double() { T i = std::numeric_limits<T>::max(); TFloat d = i; std::cout << std::fixed << i << std::endl << d << std::endl; } int main() { maxint_to_double<int, double>(); maxint_to_double<boost::intmax_t, double>(); maxint_to_double<int, float>(); return 0; } This prints: 2147483647 2147483647.000000 9223372036854775807 9223372036854775800.000000 2147483647 2147483648.000000 Note how max int can fit into a double without loss of precision and boost::intmax_t (64-bit in this case) cannot. float can't even hold an int. Now, the question: is there a way in C++ to check if the entire range of a given integer type can fit into a loating point type without loss of precision? Preferably, it would be a compile-time check that can be used in a static assertion, and would not involve enumerating the constants the compiler should know or can compute.

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  • PHP: Echo function output in function-line, not line of function call

    - by Brill
    I have a problem with my self-coded template system. The content is inserted by Include(). Now I need to add a meta redirect to one page. I know, meta redirect is not the safest way, but I need it because of it's delay possibility. Now i'm looking for a way to influence the wrapping page (template) by the wrapped page (content). So I thought a function can do this job. <?php function test($testvar){ echo $testvar;} ?> <hr /> <?php test("testtext"); ?> Of course the text echos in the line of the function call, not in the function line. Is there a way to make the function echo in the line of the function itself? In this case above the horizontal rule, not below? Of course every other best pratice for this "template problem" ist welcome! THX

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  • Excel COM Add-In dialog interrupts script

    - by usac
    Hi all! I have written an Excel COM Add-In in C++ for automation of Excel with VBA. It contains an own dialog showing some general informations about the Add-In. Now i create a button in Excel that opens the dialog. Leaving the dialog with the escape key leads to an Excel message that the script is being interrupted instead of just closing the dialog. I could suppress the interruption message with: Application.EnableCancelKey = xlDisabled But that seems not to be the solution as the script can not be interrupted any more. Here is an example how i use VBA to open the dialog: Private Sub ShowAboutDialog_Click() Dim oComAddIn As COMAddIn Set oComAddIn = Application.COMAddIns.Item("MyComAddIn.Example") oComAddIn.Connect = True Call oComAddIn.Object.ShowAboutDlg End Sub My guess is that the problem is somewhere in the message handler of the dialog: INT_PTR CALLBACK CAboutDialog::AboutDlg( HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam) { switch(uMsg) { ... case WM_COMMAND: if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL) { // Here, the ESCAPE key should also be trapped? EndDialog(hwndDlg, LOWORD(wParam)); return TRUE; } ... } return FALSE; } The Dialog is created with: DialogBox(g_hModule, MAKEINTRESOURCE(IDD_ABOUT), hWndParent, (DLGPROC)AboutDlg) Thanks a lot!

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  • How to check name of Domino Server to which lotus notes is configured? using C#

    - by Preeti
    Hi, I am trying to login Domino server. For that i am taking Lotus Notes Password and Domino Server Name from user. if (notesPassword == "" && serverName == "") { MessageBox.Show("Please enter the server name !! "); return; } else { if (connectToDomino(notesPassword, serverName)) { MessageBox.Show("Connection Established Succesfully!!.."); } else { MessageBox.Show("Connection Fail.Please Login Again To Begin"); } }//else and in public bool connectToDomino(string NotesPassword, string strDominoServerName) { try { if (_lotesNotesSession == null) { NotesSession notesSession = new Domino.NotesSessionClass(); notesSession.Initialize(NotesPassword); } return true; } catch(Exception ex) { return false; } } Here i am initializing notes password.So in this case it is just verifying Notes Password. So even if user enters invalid entry of server name above function will return true. I tried : string serverName = notesSession.ServerName; But it is showing null value. :( Regards, Preeti

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  • Requiring library consumers reference additional assembly when using certain types

    - by Thomas G. Mayfield
    I have library code that uses ICSharpCode.SharpZipLib under the hood to make it easy to use ZIP files as data sources when running integration tests. As it stands, if I reference my library from another project, the other project will compile just fine, but when it accesses the code that uses SharpZipLib, I get an exception for it not finding the zip library: failed: System.IO.FileNotFoundException : Could not load file or assembly 'ICSharpCode.SharpZipLib, Version=0.85.5.452, Culture=neutral, PublicKeyToken=1b03e6acf1164f73' or one of its dependencies. The system cannot find the file specified. If the types in my library derived from a class in SharpZipLib, it'd generate a compile error CS0012. What other ways are there for triggering a CS0012, so that using code that requires SharpZipLib (but doesn't clearly indicate it) would cause consumer code to fail compilation? I've had similar problems in the past when I've used libraries like DeftTech.DuckTyping under the hood. I'd add my library code to a new project, start working, compile, run, and then suddenly hit an edge case that I'd used duck typing to get around and get a runtime error. What I'd most like is to have the same behavior as if I'd derived from a type in the 3rd-party library, so that a reference to my derived type generates a CS0012: The type 'type' is defined in an assembly that is not referenced. You must add a reference to assembly 'assembly'.

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  • Strategies for serializing an object for auditing/logging purpose in .NET?

    - by Jiho Han
    Let's say I have an application that processes messages. Messages are just objects in this case that implements IMessage interface which is just a marker. In this app, if a message fails to process, then I want to log it, first of all for auditing and troubleshooting purposes. Secondly I might want to use it for re-processing. Ideally, I want the message to be serialized into a format that is human-readable. The first candidate is XML although there are others like JSON. If I were to serialize the messages as XML, I want to know whether the message object is XML-serializable. One way is to reflect on the type and to see if it has a parameter-less constructor and the other is to require IXmlSerializable interface. I'm not too happy with either of these approaches. There is a third option which is to try to serialize it and catch exceptions. This doesn't really help - I want to, in some way, stipulate that IMessage (or a derived type) should be xml-serializable. The reflection route has obvious disadvantages such as security, performance, etc. IXmlSerializable route locks down my messages to one format, when in the future, I might want to change the serialization format to be JSON. The other thing is even the simplest objects now must implement ReadXml and WriteXml methods. Is there a route that involves the least amount of work that lets me serialize an arbitrary object (as long as it implements the marker interface) into XML but not lock future messages into XML?

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  • Key Navigation Not Working With SL3 Treeview

    - by Chris
    I have a treeview in SL3 that is bound to a hierarchical list. Something has changed with regards to being able to navigate through the list using the up and down arrow keys. At one point, during the development of this application, I could start at the root process in the tree view, press the Enter key, and the root process would expand, showing all children processes. Some of the child processes are parent nodes for other processes. So, that functionality would work fine. Then, if I would navigate to a child node that is a parent, and press Enter, that node would expand. From that point, if I would navigate to a child node of the parent node, and then press the Up arrow key, it should select whatever item is directly above it, in this case, the corresponding parent node, but won't. It's like you can't navigate, using the UP Arrow key, to a child's parent, if you have selected the child. You can navigate down, just not UP, if the next item above it is a folder/parent node. I have no clue as to how this happened, as this functionality used to work fine, and now it doesn't. Any help would be appreciated. Thanks! Chris

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  • Can't catch KEY_VALUE_BASIC_INFORMATION.Name in CmRegisterCallback

    - by alex
    I want to hide in registry name of key value. I write driver, that using CmRegisterCallback. But I can't catch name of key value that I need. When I DbgPrint PKEY_VALUE_BASIC_INFORMATION-Name I get only symbols [ , u . Where is my mistake? Can anybody help me?My RegistryCallback source: NTSTATUS RegistryCallback(PVOID CallbackContext, PVOID Argument1, PVOID Argument2) { PDEVICE_CONTEXT pContext = (PDEVICE_CONTEXT) CallbackContext; REG_NOTIFY_CLASS Action = (REG_NOTIFY_CLASS) Argument1; UNICODE_STRING regKeyNameValueToHide = {0}; try { switch (Action) { case RegNtEnumerateValueKey: { PREG_ENUMERATE_VALUE_KEY_INFORMATION pInfo = (PREG_ENUMERATE_VALUE_KEY_INFORMATION) Argument2; //DbgPrint(pInfo->ValueName->Buffer); RtlInitUnicodeString(&regKeyNameValueToHide,L"alex-56328943333"); if(pInfo->KeyValueInformationClass == KeyValueBasicInformation) { PKEY_VALUE_BASIC_INFORMATION pKeyValueBasicInfirmation = (PKEY_VALUE_BASIC_INFORMATION) pInfo->KeyValueInformation; UNICODE_STRING regKeyNameValue = {0}; RtlInitUnicodeString(&regKeyNameValue,pKeyValueBasicInfirmation->Name); if (RtlEqualUnicodeString(&regKeyNameValue, &regKeyNameValueToHide, 1)) { return STATUS_CALLBACK_BYPASS; } } else if(pInfo->KeyValueInformationClass == KeyValueFullInformation) { PKEY_VALUE_FULL_INFORMATION pKeyValueFullInfirmation = (PKEY_VALUE_FULL_INFORMATION) pInfo->KeyValueInformation; UNICODE_STRING regKeyNameValue = {0}; RtlInitUnicodeString(&regKeyNameValue,pKeyValueFullInfirmation->Name); if (RtlEqualUnicodeString(&regKeyNameValue, &regKeyNameValueToHide, 1)) { return STATUS_CALLBACK_BYPASS; } } break; } default: { return STATUS_SUCCESS break; } } } except (EXCEPTION_EXECUTE_HANDLER) { DbgPrint("Exception in RegistryCallback!!!"); } return STATUS_SUCCESS; }

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  • Link to RSS/Atom feed, relative, doesn't work in Firefox

    - by Adrian Smith
    I have a weird problem. I generate a HTML page, hosted let's say at http://www.x.com/stuff which contains <head> <link type="application/atom+xml" rel="alternate" href="/stuff/feed"/> .. </head> The result is: In IE7 all works well - you can click on the feed icon in the browser and the feed is displayed In Firefox, view source, click on the linked /stuff/feed and you see the source of the feed, so that works as expected In Firefox, view the page (not source), then click on the feed icon in the address bar, I get an error that it can't retrieve the URL feed://http//www.x.com/stuff/feed So the problem is, that it's appending feed:// to the front of the URL and then taking out the colon : after the http. I understand that feed: is HTTP anyway so perhaps the adding of that isn't a big problem. But anyway, the fact is, that URL Firefox generates out of my <link> tag doesn't work. I have considered making the URL absolute, but I haven't found any evidence that those URLs have to be absolute, nor can I understand why that would be the case. And for various reasons it would be inconvenient in my code to generate an absolute URL. I can do it if necessary but I would prefer to see proof (e.g. specification, or Mozilla bug report) that it's necessary before making my code messy What do you think? Does anyone know of any evidence that the URL should be absolute? Or am I doing something else wrong? It seems such a simple/obvious tag, where nothing could go wrong, but I can't get it to work.

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  • Need to search email body for regex using VBA

    - by user6620
    I am trying to write a script that I can run from a rule withing outlook. The goal of this script is to search the email body for a regex pattern, \d{8}-\d{3}\(E\d\) in this case. I want to take that pattern and see if a folder with the name of the match exists and if not create one. I am not super familiar with VBA as I write mostly in python. I have copied and pasted the following bit of code together but at this time I am unable to get the MsgBox to appear when I send an email with 20120812-001(E3) in the body. I have two different versions below. --version 2-- Sub Filter(Item As Outlook.MailItem) Dim Matches, Match Dim RegEx As New RegExp RegEx.IgnoreCase = True RegEx.Pattern = "\d{8}-\d{3}(E\d)" If RegEx.Test(Item.Body) Then MsgBox "Pattern Detected" End If End Sub --Version 1-- Sub ProcessMessage(myMail As Outlook.MailItem) Dim strID As String Dim objNS As Outlook.NameSpace Dim objMsg As Outlook.MailItem Dim objMatch As Match Dim RetStr As String Set objRegExp = New RegExp objRegExp.Pattern = "\d{8}-\d{3}\(E\d\)" objRegExp.IgnoreCase = True objRegExp.Global = True strID = myMail.EntryID Set objNS = Application.GetNamespace("MAPI") Set objMsg = objNS.GetItemFromID(strID) MsgBox objMsg.Body Set objMatch = objRegExp.Execute(objMsg.Body) MsgBox objMatch End Sub

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  • Rails: constraint violation on create but not on update

    - by justinbach
    Note: This is a "railsier" (and more succinct) version of this question, which was getting a little long. I'm getting Rails behavior on a production server that I can't replicate on the development server. The codebases are identical save for credentials and caching settings, and both are powered by Oracle 10g databases with identical schema (but different data). My Rails application contains a user model, which has_one registration; registration in turn has_and_belongs_to_many company_ownerships through a registration_ownerships table. Upon registering, users fill out data pertinent to all three models, including a series of checkboxes indicating what registration_ownerships might apply to their account. On the dev server, the registration process is seamless, no matter what data is entered. On production, however, if users check off any of the company ownership fields before submitting their registration, Oracle complains about a constraint violation on the primary key of the company_ownerships table (which is a two-field key based on company_ownership_id and registration_id) and users get the standard Rails 500 error screen. In every case, I've verified that no conflicting record on these two fields exists in the production database, so I don't know why the constraint is getting violated. To further confuse things, if a user registers without listing any ownerships and later goes back and modifies their account to reflect ownership data (which is done through the same interface), the application happily complies with their request and Oracle is well-behaved (this is both on production and dev). I've spent the past couple days trying to figure out what might be causing this problem and am reaching the end of my wits. Any advice would be greatly appreciated!

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  • IUsable: controlling resources in a better way than IDisposable

    - by Ilya Ryzhenkov
    I wish we have "Usable" pattern in C#, when code block of using construct would be passed to a function as delegate: class Usable : IUsable { public void Use(Action action) // implements IUsable { // acquire resources action(); // release resources } } and in user code: using (new Usable()) { // this code block is converted to delegate and passed to Use method above } Pros: Controlled execution, exceptions The fact of using "Usable" is visible in call stack Cons: Cost of delegate Do you think it is feasible and useful, and if it doesn't have any problems from the language point of view? Are there any pitfalls you can see? EDIT: David Schmitt proposed the following using(new Usable(delegate() { // actions here }) {} It can work in the sample scenario like that, but usually you have resource already allocated and want it to look like this: using (Repository.GlobalResource) { // actions here } Where GlobalResource (yes, I know global resources are bad) implements IUsable. You can rewrite is as short as Repository.GlobalResource.Use(() => { // actions here }); But it looks a little bit weird (and more weird if you implement interface explicitly), and this is so often case in various flavours, that I thought it deserve to be new syntactic sugar in a language.

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  • How to construct LambdaExpression with conversion

    - by nerijus
    I need to sort in ajax response grid by column name. Column value is number stored as a string. Let's say some trivial class (in real-life situation there is no possibility to modify this class): class TestObject { public TestObject(string v) { this.Value = v; } public string Value { get; set; } } then simple test: [Test] public void LambdaConstructionTest() { var queryable = new List<TestObject> { new TestObject("5"), new TestObject("55"), new TestObject("90"), new TestObject("9"), new TestObject("09"), new TestObject("900"), }.AsQueryable(); var sortingColumn = "Value"; ParameterExpression parameter = Expression.Parameter(queryable.ElementType); MemberExpression property = Expression.Property(parameter, sortingColumn); //// tried this one: var c = Expression.Convert(property, typeof(double)); LambdaExpression lambda = Expression.Lambda(property, parameter); //// constructs: o=>o.Value var callExpression = Expression.Call(typeof (Double), "Parse", null, property); var methodCallExpression = Expression.Call( typeof(Queryable), "OrderBy", new[] { queryable.ElementType, property.Type }, queryable.Expression, Expression.Quote(lambda)); // works, but sorts by string values. //Expression.Quote(callExpression)); // getting: System.ArgumentException {"Quoted expression must be a lambda"} var querable = queryable.Provider.CreateQuery<TestObject>(methodCallExpression); // return querable; // <- this is the return of what I need. } Sorry for not being clear in my first post as @SLaks answer was correct but I do not know how to construct correct lambda expression in this case.

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  • Is There a Time at which to ignore IDisposable.Dispose?

    - by Mystagogue
    Certainly we should call Dipose() on IDisposable objects as soon as we don't need them (which is often merely the scope of a "using" statement). If we don't take that precaution then bad things, from subtle to show-stopping, might happen. But what about "the last moment" before process termination? If your IDisposables have not been explicitly disposed by that point in time, isn't it true that it no longer matters? I ask because unmanaged resources, beneath the CLR, are represented by kernel objects - and the win32 process termination will free all unmanaged resources / kernel objects anyway. Said differently, no resources will remain "leaked" after the process terminates (regardless if Dispose() was called on lingering IDisposables). Can anyone think of a case where process termination would still leave a leaked resource, simply because Dispose() was not explicitly called on one or more IDisposables? Please do not misunderstand this question: I am not trying to justify ignoring IDisposables. The question is just technical-theoretical. EDIT: And what about mono running on Linux? Is process termination there just as "reliable" at cleaning up unmanaged "leaks?"

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  • JavaScript access parent window from popup windows

    - by user359472
    I am trying to code this for hours and still couldn't do it. It keep tell me "Permission Denied". Here is what I am trying to accomplish. This pretty hard to explain please follow the example below. For example. domain111.com and domain222.com. When I am on domain111.com i click on the popup link , it will pop-up the domain111.com/popup.html then it redirect me to domain222.com. On this domain222.com it will redirect to couple pages before it redirect back to domain111.com with the result. I want to send the result from domain111.com to domain111.com. The process is like below. Domain111-popup to--Domain111-redirect--Domain222-redirect xxx Domain222 pages then redirect to---Domain111---SEND to parent window-Domain11 Here is my code. File name 1.hml on domain111.com <script type="text/javascript"> function IamParent() { alert('I am the parent of this window') } function PopUP() { window.open("http://domain222.com/2.htm", 'ALpop').focus(); } </script> <body> <a href="#void(0);" onclick="PopUP();" >Click</a> </body> File name 2.html on domain222.com <head> <title></title> <meta http-equiv="refresh" content="1;url=http://domain111.com/3.htm?Result=Yes" /> </head> Filename 2.htm on domain111.com <script type="text/javascript"> parent.IamParent(); //execute the function from the same domain111.com/1.htm </script> Please don't suggest AJAX or web request because it will not work with this case. Thanks for reading.

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  • How to remove the error "Cant find PInvoke DLL SQLite.interop.dll"

    - by Shailesh Jaiswal
    I am developing windows mobile application. I am using the SQLlite database. I am using the following code to connect to this database as follows SQLiteConnection cn = new SQLiteConnection(); SQLiteDataReader SQLiteDR; cn.ConnectionString = @"Data Source=F:\CompNetDB.db3"; cn.Open(); SQLiteCommand cmd = new SQLiteCommand(); cmd.CommandText = "select * from CustomerInfo"; cmd.CommandType = CommandType.Text; cmd.Connection = cn; SQLiteDR = cmd.ExecuteReader(); In the above case I am getting the error "Cant find PInvike DLL SQLite.interop.dll". I have added the DLL System.Data.SQLLite from the \SQLite.NET\bin\compactframework this folder. This is the folder which is installed by default when I installed the SQLite. In the same folder there is one DLL file named SQLlite.Interop.66.DLL. When I try to add reference to this dll it is giving error that dll can not be added. Are the two dlls SQLlite.Interop.dll & System.Interop.066.dll same ? In the above code how to solve the error "Cant find PInvoke.SQLite.Interop.dll" Please can you tell whether there is mistake in my code or I am missing something in my application?

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  • iReport / jFreeChart - Combining getItemPaint() override and series colors

    - by barneskd
    I'm attempting to create a bar chart that needs to use specific series colors for N number of categories and a separate color for 1 other category. Here is an example: http://i.imgur.com/1DeCF.png (Sorry, I don't have enough points to embed images yet) In the mockup, Categories 1-3 use a collection of 5 colors to render their series while Category 4 uses a single grey color. My first approach was to override the getItemPaint() method using a customizer class, but I can only figure out how to define a color on the category level, not the series level. Is it possible to define colors on category and/or series levels? Something like, If category != "Category4" Use colors A, B, C, D, and E in category's series Else Use color F in category's series Another thought I had was to combine iReport's Series Colors bar chart property and the getItemPaint() override; that way I could define the 5 colors to use in iReport and use the getItemPaint() override only in the case where the category equals "Category 4". So far I've had no luck combining the two; if the override is defined it overrides iReport's Series Color property.

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  • Are there some cases where Python threads can safely manipulate shared state?

    - by erikg
    Some discussion in another question has encouraged me to to better understand cases where locking is required in multithreaded Python programs. Per this article on threading in Python, I have several solid, testable examples of pitfalls that can occur when multiple threads access shared state. The example race condition provided on this page involves races between threads reading and manipulating a shared variable stored in a dictionary. I think the case for a race here is very obvious, and fortunately is eminently testable. However, I have been unable to evoke a race condition with atomic operations such as list appends or variable increments. This test exhaustively attempts to demonstrate such a race: from threading import Thread, Lock import operator def contains_all_ints(l, n): l.sort() for i in xrange(0, n): if l[i] != i: return False return True def test(ntests): results = [] threads = [] def lockless_append(i): results.append(i) for i in xrange(0, ntests): threads.append(Thread(target=lockless_append, args=(i,))) threads[i].start() for i in xrange(0, ntests): threads[i].join() if len(results) != ntests or not contains_all_ints(results, ntests): return False else: return True for i in range(0,100): if test(100000): print "OK", i else: print "appending to a list without locks *is* unsafe" exit() I have run the test above without failure (100x 100k multithreaded appends). Can anyone get it to fail? Is there another class of object which can be made to misbehave via atomic, incremental, modification by threads? Do these implicitly 'atomic' semantics apply to other operations in Python? Is this directly related to the GIL?

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  • cocoa - making a class like UIButton

    - by Mike
    For some reason that will take too much time to explain, I have to create a UIImageView based class that has some properties of a button. Imagine a class like the UISwitch (no I cannot base my class on the UISwitch) with two states, on and off. WHen the user selects one state, it runs a method like a button that was clicked and the method receives the sender id. I have already the class more or less working. The class is based on UIImageView. I am having difficulties to understand the following. WHen I create a new button I have a line that is like [myButton addTarget:self action:NSSelectorFromString(myMethod) forControlEvents:UIControlEventTouchUpInside]; This line defines a target and an action to run when the button is triggered. I my case I would need something like [myObject addTarget:self action:myMethod ifState:1] //or another thing ifState:2 I have no idea what kind of code I should put on the class to make this work. Remember that as a button the class should send the "sender" information to identify the object which triggered the action... Can you guys, transcendental gurus help? thanks.

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  • iPhone and Core Data: how to retain user-entered data between updates?

    - by Shaggy Frog
    Consider an iPhone application that is a catalogue of animals. The application should allow the user to add custom information for each animal -- let's say a rating (on a scale of 1 to 5), as well as some notes they can enter in about the animal. However, the user won't be able to modify the animal data itself. Assume that when the application gets updated, it should be easy for the (static) catalogue part to change, but we'd like the (dynamic) custom user information part to be retained between updates, so the user doesn't lose any of their custom information. We'd probably want to use Core Data to build this app. Let's also say that we have a previous process already in place to read in animal data to pre-populate the backing (SQLite) store that Core Data uses. We can embed this database file into the application bundle itself, since it doesn't get modified. When a user downloads an update to the application, the new version will include the latest (static) animal catalogue database, so we don't ever have to worry about it being out of date. But, now the tricky part: how do we store the (dynamic) user custom data in a sound manner? My first thought is that the (dynamic) database should be stored in the Documents directory for the app, so application updates don't clobber the existing data. Am I correct? My second thought is that since the (dynamic) user custom data database is not in the same store as the (static) animal catalogue, we can't naively make a relationship between the Rating and the Notes entities (in one database) and the Animal entity (in the other database). In this case, I would imagine one solution would be to have an "animalName" string property in the Rating/Notes entity, and match it up at runtime. Is this the best way to do it, or is there a way to "sync" two different databases in Core Data?

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  • How do you deal with denormalization / secondary indexes in database sharding?

    - by Continuation
    Say I have a "message" table with 2 secondary indexes: "recipient_id" "sender_id" I want to shard the "message" table by "recipient_id". That way to retrieve all messages sent to a certain recipient I only need to query one shard. But at the same time, I want to be able to make a query that ask for all messages sent by a certain sender. Now I don't want to send that query to every single shard of the "message" table. One way to do this is to duplicate the data and have a "message_by_sender" table sharded by "sender_id". The problem with that approach is that every time a message has been sent, I need to insert the message into both "message" and "message_by_sender" tables. But what if after inserting into "message" the insertion into "message_by_sender" fail? In that case the message exists in "message" but not in "message_by_sender". How do I make sure that if a message exists in "message" then it also exists in "message_by_sender" without resorting to 2 phase commit? This must be a very common issue for anyone who shards their databases. How do you deal woth it?

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  • postgresql table for storing automation test results

    - by Martin
    I am building an automation test suite which is running on multiple machines, all reporting their status to a postgresql database. We will run a number of automated tests for which we will store the following information: test ID (a GUID) test name test description status (running, done, waiting to be run) progress (%) start time of test end time of test test result latest screenshot of the running test (updated every 30 seconds) The number of tests isn't huge (say a few thousands) and each machine (say, 50 of them) have a service which checks the database and figures out if it's time to start a new automated test on that machine. How should I organize my SQL table to store all the information? Is a single table with a column per attribute the way to go? If in the future I need to add attributes but want to keep compatibility with old database format (ie I may not want to delete and create a new table with more columns), how should I proceed? Should the new attributes just be in a different table? I'm also thinking of replicating the database. In case of failure, I don't mind if the latest screenshots aren't backed up on the slave database. Should I just store the screenshots in its own table to simplify the replication? Thanks!

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  • SqlBackup from my client app

    - by Robbert Dam
    I have an client app that runs on several machines, and connects to a single SQL database. On the client app, the user has the possiblity to use a local SQL (CE) database or connect to a remote SQL database. There is also a box where a backup location can be set. For the backup of the remote SQL database I use the following code: var bdi = new BackupDeviceItem(backupFile, DeviceType.File); var backup = new Backup { Database = "AppDb", Initialize = true }; backup.Devices.Add(bdi); var server = new Server(connection); backup.SqlBackup(server); When developing my application, I wasn't aware that the given backupFile is written on the machine where the SQL server runs! And not on the client machine. What I want is "dump" all the data from my database to a local file. (Why? Because users may enter a network location in the "backup location" box, and backing up SQL immediately to a network location fails. So need to write local first and then copy to the network in that case.) I there an alternative to the method above?

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