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  • can bind successfully to the ldap server, but needs to know how to find user w/i AD

    - by Brad
    I create a login form to bind to the ldap server, if successful, it creates a session (which the user's username is stored within), then I go to another page that has session_start(); and it works fine. What I want to do now, is add code to test if that user is a member of a specific group. So in theory, this is what I want to do if(username session is valid) { search ldap for user -> get list of groups user is member of foreach(group they are member of) { switch(group) { case STAFF: print 'they are member of staff group'; $access = true; break; default: print 'not a member of STAFF group'; $access = false; break; } if(group == STAFF) { break; } } if($access == TRUE) { // you have access to the content on this page } else { // you do not have access to this page } } How do I do a ldap_search w/o binding? I don't want to keep asking for their password on each page, and I can't pass their password thru a session. Any help is appreciated.

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  • Multiple "ObjectChangeTracker" getting created, can it be avoided?

    - by user555937
    Hi, We are working on a POC where we have following architecture (MVVM), WPF(Client) + WCF + Model(DataAccess)+ ADO.Net Entity Framework 4.0 (with SQL Server 2008 R2 as DB) All are different projects. In the DataAccess layer we have created different Entity Models(edmx) based on the functionality. The tables under perticular flow are grouped and created different entity models. We are using self tracking entities to and fro to communicate with the WPF client through wcf service. For Single model everything works fine. But when we created a Multiple models then few issues started coming. Mutliple models have few duplicate tables/entities. Two probels are, 1) When we try to access entities from different models mutiple objects "ObjectChangeTracker" are getting created. E.g. CompanyModel(edmx) - Company(Entity) - ObjectChangeTracker, ObjectState ProductModel(edmx) - Customer(Entity) - ObjectChangeTracker1, ObjectState1 OrderModel(edmx) - Oder(Entity) - ObjectChangeTracker2, ObjectState2 Is there any way to avoid this? 2) There are few tables which shared across the Models, E.g. Company(Entity) is used in All above mdoels. During compile time it does not thow any error. But run time It gives error saying "Schema specified is not valid. Errors: The mapping of CLR type to EDM type is ambiguous because multiple CLR types match the EDM type "Company"".. To resolve this, we renamed the entities with some prefix to make them Unique. Is there any other way we can resolve this without changing the name of the entity in the same assembly? Thanks in advance and appreciate if anyone has approach for these issues. Thanks, Kiran

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  • PROLOG - DCG parsing

    - by user2895589
    Hello I am new Prolog and DGC.I want to write a DCG to parse time expressions like 10.20 am or 12 oclock. how can I check 10.20 am is valid expression or not for Olcock I wrote some code. oclock --> digit1,phrase1. digit1 --> [T],{digit1(T)}. digit1(1). digit1(2). digit1(3). digit1(4). digit1(5). digit1(6). digit1(7). digit1(8). digit1(9). digit1(10). digit1(11). digit1(12). phrase1 --> [P],{phrase1(P)}. phrase1(Oclock). i ma checking by query oclock([1,oclock],[]). can someone help me on this.

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  • PHP / Zend custom date input formats

    - by mld
    Hi, I'm creating a library component for other developers on my team using PHP and Zend. This component needs to be able to take as input a date (string) and another string telling it the format of that date. Looking through the Zend documentation and examples, I thought I found the solution - $dateObject = Zend_Date('13.04.2006', array('date_format' => 'dd.MM.yyyy')); this line, however, throws an error - call to undefined function. So instead I tried this - $dt = Zend_Locale_Format::getDate('13.04.2006', array('date_format' => 'dd.MM.yyyy')); This gets the job done, but throws an error if a date that is entered isn't valid. The docs make it look like you can use the isDate() function to check validity - Zend_Date::isDate('13.04.2006', array('date_format' => 'dd.MM.yyyy')) but this line always returns false. So my questions - Am I going about this the right way? If not, is there a better way to handle this via Zend or straight PHP? If I do use Zend_Locale_Format::getDate(), do I need to worry about a locale being set elsewhere and changing the results of the call? I'm locked into PHP 5.2.6 on windows, btw... so 5.3+ functions & strptime() are out.

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  • Best practice for debug Asserts during Unit testing

    - by Steve Steiner
    Does heavy use of unit tests discourage the use of debug asserts? It seems like a debug assert firing in the code under test implies the unit test shouldn't exist or the debug assert shouldn't exist. "There can be only one" seems like a reasonable principle. Is this the common practice? Or do you disable your debug asserts when unit testing, so they can be around for integration testing? Edit: I updated 'Assert' to debug assert to distinguish an assert in the code under test from the lines in the unit test that check state after the test has run. Also here is an example that I believe shows the dilema: A unit test passes invalid inputs for a protected function that asserts it's inputs are valid. Should the unit test not exist? It's not a public function. Perhaps checking the inputs would kill perf? Or should the assert not exist? The function is protected not private so it should be checking it's inputs for safety.

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  • Radio buttons change variable in JavaScript

    - by dmanexe
    I have two fields which calculate a total, but I have a radio button pair that determines a variable within the equation. Here's the radio button code: <input type="radio" name="estimate_pool_shape" value="1" /> Angle <input type="radio" name="estimate_pool_shape" value=".86392" /> Freeform Immediately after that, this JavaScript is then calculating the surface area of the pool based of these fields and script: (Length <input type="text" size="5" name="estimate_pool_length" onBlur="conv2inches(document.forms.mainform);" />) x (Width <input type="text" name="estimate_pool_width" size="5" onBlur="conv2inches(document.forms.mainform);" />) The following JavaScript already works to update the fields, I just need the variable it uses to set the field values to change based on the radio buttons. function conv2inches(mainform) { var oin; var oinches; if(isNaN(mainform.estimate_pool_width.value)||isNaN(mainform.estimate_pool_length.value)){ alert("Please enter numbers only"); return false; } oin = ((mainform.estimate_pool_width.value) + (mainform.estimate_pool_length.value) * %%%RADIO BUTTON VARIABLE HERE%%%); oinches = (oin); if(oinches==0){ alert("Please enter valid values into the boxes"); } mainform.estimate_pool_sqft.value = oinches; return false; }

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  • Can't post with Perl's Net::Blogger

    - by Ovid
    I'm trying to automatically post to blogger using Perl's Net::Blogger but it keeps returning false and not posting. The main portion of my code looks like this: use Net::Blogger; my $blogger = Net::Blogger->new({ debug => 1, appkey => '0123456789ABCDEF', # doesn't matter? blogid => $blogid, username => $username, password => $password, }); say 'got to here'; my $result = $blogger->newPost({ postbody => \'<p>This is text</p><hr/><p><strong>Whee!</strong></p>', publish => 1, }); say 'done posting'; use Data::Dumper; print Dumper($result); Sure enough, $result is 0 and in checking the blog, nothing has been posted. The error I'm getting when I enable debugging is: Element '' can't be allowed in valid XML message. Died. at /Library/Perl/5.10.1/SOAP/Lite.pm line 1410. What am I doing wrong? If you can suggest an alternative to Net::Blogger, that would be fine.

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  • How can I include DBNull as a value in my strongly typed dataset?

    - by Beska
    I've created a strongly typed dataset (MyDataSet) in my .NET app. For the sake of simplicity, we'll say it has one DataTable (MyDataTable), with one column (MyCol). MyCol has its DataType property set to "System.Int32", and its AllowDBNull property set to "true". I'd like to manually create a new row, and add it to this dataset. I create the row without a problem, with something like: MyDataSet.MyDataTableRow myRow = MySimpleDataSet.MyDataTable.NewItemRow(); Fine. However, when I try to set the value to DBNull: myRow.MyCol = DBNull.Value; I'm told that I can't do it...that it can't cast that to an int. This makes sense, in a way, since I've defined it to be an int...but then how can I get DBNull in there? Am I not supposed to be able to have DBNull in there? Isn't that what the AllowDBNull property is for? I'm obviously missing something fundemental. Can someone help explain what it is? EDIT: I also tried entering "int?" as the DataType, but Visual Studio throws an error when I enter it, saying that "Column requires a valid DataType."

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  • What is the nicest way to parse this in C++ ?

    - by ereOn
    Hi, In my program, I have a list of "server address" in the following format: host[:port] The brackets here, indicate that the port is optional. host can be a hostname, an IPv4 or IPv6 address. port, if present can be a numeric port number or a service string (like: "http" or "ssh"). If port is present and host is an IPv6 address, host must be in "bracket-enclosed" notation (Example: [::1]) Here are some valid examples: localhost localhost:11211 127.0.0.1:http [::1]:11211 ::1 [::1] And an invalid example: ::1:80 // Invalid: Is this the IPv6 address ::1:80 and a default port, or the IPv6 address ::1 and the port 80 ? ::1:http // This is not ambigous, but for simplicity sake, let's consider this is forbidden as well. My goal is to separate such entries in two parts (obviously host and port). I don't care if either the host or port are invalid as long as they don't contain a : (290.234.34.34.5 is ok for host, it will be rejected in the next process); I just want to separate the two parts, or if there is no port part, to know it somehow. I tried to do something with std::stringstream but everything I come up to seems hacky and not really elegant. How would you do this in C++ ? I don't mind answers in C but C++ is prefered. Any boost solution is welcome as well. Thank you.

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  • Concrete examples of state sharing between multiple viewmodels (WPF MVVM)

    - by JohnMetta
    I have a WPF/Entity Framework (4.0) project with many objects. I'd like to build the application so that that I can have object selection state shared across viewmodels. For Example: We have Cars, Drivers, Passengers, and Cargo classes. We also have UserControls for CarList, DriverList, etc. and editor windows for CarEditor, DriverEditor, etc. Furthermore, we have viewmodels for all of these (CarListViewModel, DriverListViewModel, CargoEditorViewModel, etc). This all composes a dockable interface where the user can have multiple object lists, editors, and viewers open. What I want is a concrete code example of how to wireup multiple viewmodels so that selecting a car in the CarList will cause that car to go live in the CarEditorView, but also be selected in any other view for which the context is valid (such as a DriverByCarView- or just DriverList if there is a filter predicate). There are a number of suggestions and discussions based on this question. The two methods that seem to dominate are: 3018307: Discusses state sharing by mentioning a messaging subsystem 1159035: Discusses state sharing by using an enclosing viewmodel Is one of these approaches better than the other? Does anyone have a concrete example of either/both of these methods in the form of a write-up or small code project? I'm still learning WPF, so pointers to entry points for reading API fundamentals are appreciated, but looking at code examples is where I usually go. Thanks In case anyone is interested, here are some other similar discussions: 3816961: Discusses returning multiple viewmodels depending on object type (i.e. a collection of arbitrary types adhering to a specific interface) 1928130: Discusses whether it is a good idea to aggregate viewmodels as properties of other viewmodels (e.g. a MainWindow viewmodel composed of panel viewmodels) 1120061: Essentially discusses whether to have use a viewmodel-per-model strategy or a viewmodel-per-view-element strategy. 4244222: Discusses whether or not to nest the viewmodels when using a nested object hierarchy. 4429708: Discusses sharing collections between viewmodels directly, but doesn't go into detail. List item: Discusses managing multiple selections within a single viewmodel.

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  • How can I test a form that requires the entry of two random characters from a security phrase?

    - by lawm
    I need to test a two-stage login system which first asks for your email address and password and then presents the user with two select lists containing [a-zA-Z0-9]. The labels beside the drop down's are of the form 'Select character X from your security phrase', where X is a random character index from a known security phrase. I'd rather not stub the code for an acceptance test, so is it possible to write a matcher in cucumber which will, given that we know the whole phrase, select the required character in each of the two lists? Here is the scenario I have so far and the steps involved: Scenario: valid login email, password and secret phrase takes me to the dashboard Given I am not logged in When I log in as "[email protected]" Then I should be on the dashboard page And I should see "Your Dashboard" When /^I log in as "([^\"]*)"$/ do |login| visit path_to('Login page') fill_in "Email", :with => login fill_in "Password", :with => "Password123" click_button "Log in" response.should contain("Please verify some characters from your security phrase") select "a", :from => "Select character X of your security phrase" select "b", :from => "Select character Y of your security phrase" click_button "Submit" end For example, if the security phrase is 'Secret123', X = 3 and Y = 8, the above would have to produce the equivalent of: select "c", :from => "Select character 3 of your security phrase" select "2", :from => "Select character 8 of your security phrase" The numbers X and Y in the actual page are inside span#svc_1 and span#svc_2 respectively. Thanks,

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  • SharePoint Lists.asmx's UpdateListItems() returns too much data

    - by Philipp Schmid
    Is there a way to prevent the UpdateListItems() web service call in SharePoint's Lists.asmx endpoint from returning all of the fields of the newly created or updated list item? In our case an event handler attached to our custom list is adding some rather large field values which are turned to the client unnecessarily. Is there a way to tell it to only return the ID of the newly created (or updated) list item? For example, currently the web service returns something like this: <Results xmlns="http://schemas.microsoft.com/sharepoint/soap/"> <Result ID="1,Update"> <ErrorCode>0x00000000</ErrorCode> <z:row ows_ID="4" ows_Title="Title" ows_Modified="2003-06-19 20:31:21" ows_Created="2003-06-18 10:15:58" ows_Author="3;#User1_Display_Name" ows_Editor="7;#User2_Display_Name" ows_owshiddenversion="3" ows_Attachments="-1" ows__ModerationStatus="0" ows_LinkTitleNoMenu="Title" ows_LinkTitle="Title" ows_SelectTitle="4" ows_Order="400.000000000000" ows_GUID="{4962F024-BBA5-4A0B-9EC1-641B731ABFED}" ows_DateColumn="2003-09-04 00:00:00" ows_NumberColumn="791.00000000000000" xmlns:z="#RowsetSchema" /> </Result> ... </Results> where as I am looking for a trimmed response only containing for example the ows_ID attribute: <Results xmlns="http://schemas.microsoft.com/sharepoint/soap/"> <Result ID="1,Update"> <ErrorCode>0x00000000</ErrorCode> <z:row ows_ID="4" /> </Result> ... </Results> I have unsuccessfully looked for a resource that documents all of the valid attributes for both the <Batch> and <Method> tags in he updates XmlNode parameter of UpdateListItems() in the hope that I will find a way to specify the fields to return. A solution for WSS 3.0 would be preferable over an SP 2010-only solution.

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  • EF in a UserControl can't see the app.config?

    - by Sven
    I just created a user control. This control also makes use of my static Entity Framework class to load two comboboxes. All is well and runs without a problem. Design and runtime are working. Then when I stop the application all the forms that contain my UserControl don't work any more in design time. I just see two errors: Error1: The specified named connection is either not found in the configuration, not intended to be used with the EntityClient provider, or not valid. Error 2: The variable ccArtikelVelden is either undeclared or was never assigned. (ccArtikelVelde is my UserControl) Runtime everything is still working My static EF Repositoy class: public class BSManagerData { private static BSManagerEntities _entities; public static BSManagerEntities Entities { get { if (_entities == null) _entities = new BSManagerEntities(); return _entities; } set { _entities = value; } } } Some logic happening in my UserControl to load the data in the comboboxes: private void LaadCbx() { cbxCategorie.DataSource = (from c in BSManagerData.Entities.Categories select c).ToList(); cbxCategorie.DisplayMember = "Naam"; cbxCategorie.ValueMember = "Id"; } private void cbxCategorie_SelectedIndexChanged(object sender, EventArgs e) { cbxFabrikant.DataSource = from f in BSManagerData.Entities.Fabrikants where f.Categorie.Id == ((Categorie)cbxCategorie.SelectedItem).Id select f; cbxFabrikant.DisplayMember = "Naam"; cbxFabrikant.ValueMember = "Id"; } The only way to make my forms work again, design time, is to comment out the EF part in the UserControl (see above) and rebuild. It's very strange, everything is in the same assembly, same namespace (for the sake of simplicity). Anyone an idea?

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  • C++ -- Why should we use operator -> to access member functions of a SmartPtr?

    - by q0987
    Hello all, The question is given in the last two lines of code. template<class T> // template class for smart class SmartPtr { // pointers-to-T objects public: SmartPtr(T* realPtr = 0); T* operator->() const; T& operator*() const; T* Detach( void ) { T* pData = pointee; pointee = NULL; return pData; } private: T *pointee; ... }; class TestClass {} SmartPtr<TestClass> sPtr(new TestClass); TestClass* ptrA = sPtr->Detach(); // why I always see people use this method to access member functions of a Smart pointer. We can use sPtr-> b/c we have defined operator->() in SmartPtr. TestClass* ptrB = sPtr.Detach(); // Question: Is this a valid C++ way? If not, why? Thank you

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  • Margically appearing margin in footer. Could use some fresh eye's on this.

    - by Banderdash
    Hi chaps! Got a nearly finished coded comp here: http://clients.pixelbleed.net/biodesign/ I realize it's not completely valid, what with my nesting of li's and ul's within A tags. Unfortunately that's the way it has to be. My issue is with the very bottom of the footer. It has a space showing the body's background color beneath it. Tried a number of things and this space after the black link bar on the very bottom is a resistant little bugger. Ideally the black box on the bottom should rest against the very base of the view-port, at least when the content is sufficiently long--which it is in this case. If someone would like to take a quick peak at my source and give me some ideas I'd be very grateful. The CSS can be found here: http://clients.pixelbleed.net/biodesign/css/core.css And, yes, I've tried removing the height:100%. Makes no difference it seems. I do believe the issue to be with the footer, as when I remove these Div's the content rests as it should. Just don't see anything in my CSS to cause the margin/spacing issue though. Thanks so much.

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  • How to convert "0" and "1" to false and true

    - by Chris
    I have a method which is connecting to a database via Odbc. The stored procedure which I'm calling has a return value which from the database side is a 'Char'. Right now I'm grabbing that return value as a string and using it in a simple if statement. I really don't like the idea of comparing a string like this when only two values can come back from the database, 0 and 1. OdbcCommand fetchCommand = new OdbcCommand(storedProc, conn); fetchCommand.CommandType = CommandType.StoredProcedure; fetchCommand.Parameters.AddWithValue("@column ", myCustomParameter); fetchCommand.Parameters.Add("@myReturnValue", OdbcType.Char, 1). Direction = ParameterDirection.Output; fetchCommand.ExecuteNonQuery(); string returnValue = fetchCommand.Parameters["@myReturnValue"].Value.ToString(); if (returnValue == "1") { return true; } What would be the proper way to handle this situation. I've tried 'Convert.ToBoolean()' which seemed like the obvious answer but I ran into the 'String was not recognized as a valid Boolean. ' exception being thrown. Am I missing something here, or is there another way to make '1' and '0' act like true and false? Thanks!

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  • Event Dispatching, void pointer and alternatives

    - by PeeS
    i have my event dispatching / handling functionality working fine, but there is one issue that i need to resolve. Long story short, here are the details. // The event structure struct tEventMessage { // Type of the event int Type; // (void*) Allows those to be casted into per-Type objects void *pArgument1; void *pArgument2; }; I am sending events from different modules in my engine by using the above structure, which requires a pointer to an argument. All messages are queued, and then dispatched on the next ::Tick(). It works fine, untill i try to send something that doesn't exist in next ::Tick, for example: When a mouse click is being handled, it calculates the click coordinates in world space. This is being sent with a pointer to a vector representing that position, but after my program quits that method, this pointer gets invalid obviously, cause local CVector3 is destructed: CVector2 vScreenSpacePosition = vAt; CVector3 v3DPositionA = CVector3(0,0,0); CVector3 v3DPositionB = CVector3(0,0,0); // Screen space to World space calculation for depth zNear v3DPositionA = CMath::UnProject(vScreenSpacePosition, m_vScreenSize, m_Level.GetCurrentCamera()->getViewMatrix(), m_Level.GetCurrentCamera()->getProjectionMatrix(), -1.0 ); // Screen space to World space calculation for depth zFar v3DPositionB = CMath::UnProject(vScreenSpacePosition, m_vScreenSize, m_Level.GetCurrentCamera()->getViewMatrix(), m_Level.GetCurrentCamera()->getProjectionMatrix(), 1.0); // Send zFar position and ScreenSpace position to the handlers // Obviously both vectors won't be valid after this method quits.. CEventDispatcher::Get()->SendEvent(CIEventHandler::EVENT_SYSTEM_FINGER_DOWN, static_cast<void*>(&v3DPositionB), static_cast<void*>(&vScreenSpacePosition)); What i want to ask is, if there is any chance i could make my tEventMessage more 'template', so i can handle sending objects like in the above situation + use what is already implemented? Can't figure it out at the moment.. What else can be done here to allow me to pass some locally available data ? Please can somebody shed a bit of light on this please?

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  • Rationale of C# iterators design (comparing to C++)

    - by macias
    I found similar topic: http://stackoverflow.com/questions/56347/iterators-in-c-stl-vs-java-is-there-a-conceptual-difference Which basically deals with Java iterator (which is similar to C#) being unable to going backward. So here I would like to focus on limits -- in C++ iterator does not know its limit, you have by yourself compare the given iterator with the limit. In C# iterator knows more -- you can tell without comparing to any external reference, if the iterator is valid or not. I prefer C++ way, because once having iterator you can set any iterator as a limit. In other words if you would like to get only few elements instead of entire collection, you don't have to alter the iterator (in C++). For me it is more "pure" (clear). But of course MS knew this and C++ while designing C#. So what are the advantages of C# way? Which approach is more powerful (which leads to more elegant functions based on iterators). What do I miss? If you have thoughts on C# vs. C++ iterators design other than their limits (boundaries), please also answer. Note: (just in case) please, keep the discussion strictly technical. No C++/C# flamewar.

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  • Make password case unsensitive in shared ASP.Net membership tables web ap

    - by bill
    Hi all, i have two webapps.. that share ASP.Net membership tables. Everything works fine except i cannot remove case-sensitivity in one of the apps the way i am doing it in the other. in the non-working app void Login1_LoggingIn(object sender, LoginCancelEventArgs e) { string username = Login1.UserName.Trim(); if (!string.IsNullOrEmpty(username)) { MembershipUser user = Membership.GetUser(username); if (user != null) { // Only adjust the UserName if the password is correct. This is more secure // so a hacker can't find valid usernames if we adjust the case of mis-cased // usernames with incorrect passwords. string password = Login1.Password.ToUpper(); if (Membership.ValidateUser(user.UserName, password)) { Login1.UserName = user.UserName; } } } } is not working. the password is stored as all upper case. Converted at the time the membership user is created! So if the password is PASSWORD, typing PASSWORD allows me to authenticate. but typing password does not! Even though i can see the string being sent is PASSWORD (converted with toUpper()). I am at a complete loss on this.. in the other app i can type in lower or upper or mixed and i am able to authenticate. In the other app i am not using the textboxes from the login control though.. not sure if this is making the difference??

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  • json parser empty result

    - by graybow
    I'm new in gwt and new in using firebug.I have valid json result from tesdb3.php {"item": [{"kode":"002","nama":"bambang gentolet"}, {"kode":"012","nama":"Algiz"}]} I add the xml with inherits name='com.google.gwt.json.JSON'/ inherits name="com.google.gwt.http.HTTP" / then i try to show it in the gwt with this code. public class Tesdb3 implements EntryPoint { String url= "http://localhost/phpmyadmin/tesdb3/datauser.php"; public void LoadData() throws RequestException{ RequestBuilder builder = new RequestBuilder(RequestBuilder.GET, URL.encode(url)); builder.sendRequest(null, new RequestCallback(){ @Override public void onError(Request request, Throwable exception) { Window.alert("error " + exception); } public void onResponseReceived(Request request, Response response) { if (200 == response.getStatusCode()) { Window.alert("ok -" + response.getText() + "-" + response.getStatusCode()); } else { Window.alert("error2 -" + response.getText()+ response.getStatusText() + "-" + response.getStatusCode()); } } }); } public void onModuleLoad() { try { LoadData(); } catch (RequestException e) { e.printStackTrace(); } } } I run it in development mode. not hosted mode. My code didn't show any error. But the result in window alert is "error2 --OK-0". result Net from firebug is 7 request: get Tesdb3.html?gwt.codeserv = 200ok get Tesdb3.css = 200ok get tesdb3.nocache.js = 200ok get hosted.html?tesdb3 = aborted get standard.css = 304 not modified get hosted.html?tesdb3 = 403 not modified get datauser.php = 200ok my question is: Why the response status code is 0, and the response status text is 'OK'? there was no eror in json or java code. why response.getText is empty? Why i can't get any json result even a single character?

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  • Prolog Beginner: How to make unique values for each Variable in a predicate.

    - by sixtyfootersdude
    I have a prolog predicate: DoStuff( [A|B] ) :- <Stuff that I do> ... </Stuff that I do> It is all done except it needs to do return unique values. Ie if you do: ?- DoStuff(A,B,C,D). it should return: A=1; B=2; C=3; D=4. (Or something similar, the key point is that all of the values are unique). However you should be able to do this too: ?- DoStuff(A,A,B,B). And still get a valid answer. Ie: A=1; B=2. How can I do this? What I was planning on doing was something like this: DoStuff( [A|B] ) :- <Stuff that I do> ... </Stuff that I do> unique([A|B]). unique([]). unique([A|B]) :- A is not B. However I think that will make DoStuff([A,A,B]) not work because not all values will be unique.

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  • google app engine atomic section???

    - by bokertov
    hi, Say you retrieve a set of records from the datastore (something like: select * from MyClass where reserved='false'). how do i ensure that another user doesn't set the reserved is still false? I've looked in the Transaction documentation and got shocked from google's solution which is to catch the exception and retry in a loop. Any solution that I'm missing - it's hard to believe that there's no way to have an atomic operation in this environment. (btw - i could use 'syncronize' inside the servlet but i think it's not valid as there's no way to ensure that there's only one instance of the servlet object, isn't it? same applies to static variable solution) Any idea on how to solve??? (here's the google solution: http://code.google.com/appengine/docs/java/datastore/transactions.html#Entity_Groups look at: Key k = KeyFactory.createKey("Employee", "k12345"); Employee e = pm.getObjectById(Employee.class, k); e.counter += 1; pm.makePersistent(e); This requires a transaction because the value may be updated by another user after this code fetches the object, but before it saves the modified object. Without a transaction, the user's request will use the value of counter prior to the other user's update, and the save will overwrite the new value. With a transaction, the application is told about the other user's update. If the entity is updated during the transaction, then the transaction fails with an exception. The application can repeat the transaction to use the new data. THANKS!

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  • How do I avoid a race condition in my Rails app?

    - by Cathal
    Hi, I have a really simple Rails application that allows users to register their attendance on a set of courses. The ActiveRecord models are as follows: class Course < ActiveRecord::Base has_many :scheduled_runs ... end class ScheduledRun < ActiveRecord::Base belongs_to :course has_many :attendances has_many :attendees, :through => :attendances ... end class Attendance < ActiveRecord::Base belongs_to :user belongs_to :scheduled_run, :counter_cache => true ... end class User < ActiveRecord::Base has_many :attendances has_many :registered_courses, :through => :attendances, :source => :scheduled_run end A ScheduledRun instance has a finite number of places available, and once the limit is reached, no more attendances can be accepted. def full? attendances_count == capacity end attendances_count is a counter cache column holding the number of attendance associations created for a particular ScheduledRun record. My problem is that I don't fully know the correct way to ensure that a race condition doesn't occur when 1 or more people attempt to register for the last available place on a course at the same time. My Attendance controller looks like this: class AttendancesController < ApplicationController before_filter :load_scheduled_run before_filter :load_user, :only => :create def new @user = User.new end def create unless @user.valid? render :action => 'new' end @attendance = @user.attendances.build(:scheduled_run_id => params[:scheduled_run_id]) if @attendance.save flash[:notice] = "Successfully created attendance." redirect_to root_url else render :action => 'new' end end protected def load_scheduled_run @run = ScheduledRun.find(params[:scheduled_run_id]) end def load_user @user = User.create_new_or_load_existing(params[:user]) end end As you can see, it doesn't take into account where the ScheduledRun instance has already reached capacity. Any help on this would be greatly appreciated.

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  • Unit testing a method with many possible outcomes

    - by Cthulhu
    I've built a simple~ish method that constructs an URL out of approximately 5 parts: base address, port, path, 'action', and a set of parameters. Out of these, only the address part is mandatory, the other parts are all optional. A valid URL has to come out of the method for each permutation of input parameters, such as: address address port address port path address path address action address path action address port action address port path action address action params address path action params address port action params address port path action params andsoforth. The basic approach for this is to write one unit test for each of these possible outcomes, each unit test passing the address and any of the optional parameters to the method, and testing the outcome against the expected output. However, I wonder, is there a Better (tm) way to handle a case like this? Are there any (good) unit test patterns for this? (rant) I only now realize that I've learned to write unit tests a few years ago, but never really (feel like) I've advanced in the area, and that every unit test is a repeat of building parameters, expected outcome, filling mock objects, calling a method and testing the outcome against the expected outcome. I'm pretty sure this is the way to go in unit testing, but it gets kinda tedious, yanno. Advice on that matter is always welcome. (/rant) (note) christmas weekend approaching, probably won't reply to suggestions until next week. (/note)

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  • AIX specific socket programming query

    - by kumar_m_kiran
    Hi All, Question 1 From SUSE man pages, I get the below details for socket connect options If the initiating socket is connection-mode, then connect() shall attempt to establish a connection to the address specified by the address argument. If the connection cannot be established immediately and O_NONBLOCK is not set for the file descriptor for the socket, connect() shall block for up to an unspecified timeout interval until the connection is established. If the timeout interval expires before the connection is established, connect() shall fail and the connection attempt shall be aborted. If connect() is interrupted by a signal that is caught while blocked waiting to establish a connection, connect() shall fail and set errno to [EINTR], but the connection request shall not be aborted, and the connection shall be established asynchronously. Question : Is the above contents valid for AIX OS (especially the connection time-out, timed wait ...etc)?Because I do not see it in AIX man pages (5.1 and 5.3) Question 2 I have a client socket whose attributes are a. SO_RCVTIMEO ,SO_SNDTIMEO are set for 5 seconds. b. AF_INET and SOCK_STREAM. c. SO_LINGER with linger on and time is 5 seconds. d. SO_REUSEADDR is set. Note that the client socket is not O_NONBLOCK. Question : Now since O_NONBLOCK is not set and SO_RCVTIMEO and SO_SNDTIMEO is set for 5 seconds, does it mean a. connect in NON Blocking or Blocking? b. If blocking, is it timed blocking or "infinite" time blocking? c. If it is infinite, How do I establish a "connect" system call which is O_BLOCKING with timeout to t secs. Sorry if the questions are be very naive. Thanks in advance for your input.

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