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• Performing centralized authorization for multiple applications

  - by Vaibhav

  Here's a question that I have been wrestling with for a while. We have a situation wherein we have a number of applications that we have created. These have grown organically over a period of time. All of these applications have permissions code built into them that controls access to various parts of the application depending on whether the currently logged in user has the necessary permissions or not. Alongside these applications is a utility application which allows an administrator to map users to permissions for all applications - the way it works is that every application has code which reads this external database of the said utility application to check if the currently logged in user has the necessary permission or not. Now, the question is this. Should the user-permissions mapping information reside in and be owned by the applications themselves, or is it okay to have this information reside within an external entity/DB (as in this case the utility application's database). Part of me thinks that application permissions are very specific to the application context itself, so shouldn't be separated from the application itself. But I am not sure. Any comments?

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• how to emulate thread local storage at user space in C++ ?

  - by vprajan

  I am working on a mobile platform over Nucleus RTOS. It uses Nucleus Threading system but it doesn't have support for explicit thread local storage i.e, TlsAlloc, TlsSetValue, TlsGetValue, TlsFree APIs. The platform doesn't have user space pthreads as well. I found that __thread storage modifier is present in most of the C++ compilers. But i don't know how to make it work for my kind of usage. How does __thread keyword can be mapped with explicit thread local storage? I read many articles but nothing is so clear for giving me the following basic information will __thread variable different for each thread ? How to write to that and read from it ? does each thread has exactly one copy of the variable ? following is the pthread based implementation: pthread_key_t m_key; struct Data : Noncopyable { Data(T* value, void* owner) : value(value), owner(owner) {} int* value; }; inline ThreadSpecific() { int error = pthread_key_create(&m_key, destroy); if (error) CRASH(); } inline ~ThreadSpecific() { pthread_key_delete(m_key); // Does not invoke destructor functions. } inline T* get() { Data* data = static_cast<Data*>(pthread_getspecific(m_key)); return data ? data->value : 0; } inline void set(T* ptr) { ASSERT(!get()); pthread_setspecific(m_key, new Data(ptr, this)); } How to make the above code use __thread way to set & get specific value ? where/when does the create & delete happen? If this is not possible, how to write custom pthread_setspecific, pthread_getspecific kind of APIs. I tried using a C++ global map and index it uniquely for each thread and retrieved data from it. But it didn't work well.

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• C++: Declare static variable in function argument list

  - by MDC

  Is there any way at all in C++ to declare a static variable while passing it to a function? I'm looking to use a macro to expand to the expression passed to the function. The expression needs to declare and initialize a static variable on that particular line (based on the filename and line number using FILE and LINE). int foo(int b) { int c = b + 2; return c; } int main() { int a = 3; a = foo(static int h = 2); //<---- see this! cout << a; return 0; } The problem I'm trying to solve is getting the filename and line number with the FILE and LINE macros provided by the preprocessor, but then creating a lookup table with integer keys leading to the FILE, LINE pairs. For example, the key 89 may map to file foo.cpp, line 20. To get this to work, I'm trying to use local static variables, so that they are initialized only once per line execution. The static variable will be initialized by calling a function that calculates the integer key and adds an entry to the lookup table if it is not there. Right now the program uses a message class to send exception information. I'm writing a macro to wrap this class into a new class: WRAPPER_MACRO(old_class_object) will expand to NewClass(old_class_object, key_value). If I add the static variable declaration as a second line right before this, it should work. The problem is that in most places in the code, the old class object is passed as an argument to a function. So the problem becomes declaring and initializing the static variable somehow with the macro, while keeping the existing function calls.

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• Help! I'm a Haskell Newbie

  - by Darknight

  I've only just dipped my toe in the world of Haskell as part of my journey of programming enlightenment (moving on from, procedural to OOP to concurrent to now functional). I've been trying an online Haskell Evaluator. However I'm now stuck on a problem: Create a simple function that gives the total sum of an array of numbers. In a procedural language this for me is easy enough (using recursion) (c#) : private int sum(ArrayList x, int i) { if (!(x.Count < i + 1)) { int t = 0; t = x.Item(i); t = sum(x, i + 1) + t; return t; } } All very fine however my failed attempt at Haskell was thus: let sum x = x+sum in map sum [1..10] this resulted in the following error (from that above mentioned website): Occurs check: cannot construct the infinite type: a = a -> t Please bear in mind I've only used Haskell for the last 30 minutes! I'm not looking simply for an answer but a more explanation of it. Thanks in advanced.

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• How to use accessors within the same class in Objective C?

  - by Azeworai

  Hi, I have a few properties defined in my header file like so @property (assign) bool connectivity_N; @property (assign) bool isConnected_N; In my implementation file I have an init and the synthesized properties like so @implementation Map @synthesize connectivity_N; @synthesize isConnected_N; a init to set the initial values like so -(id) init { if( (self=[super init]) ) { //initialise default properties self.connectivity_N=NO; self.isConnected_N=NO; } return self; } I'm running into an error that states Error: accessing unknown 'connectivity_N' class method. In this public method within the class +(bool) isConnectable:(directions) theDirection{ bool isTheDirectionConnectable= NO; switch (theDirection) { case north: isTheDirectionConnectable= self.connectivity_N; break; I'm not sure why is this so as I'm trying to grab the value of the property. According to the apple developer documentation "The default names for the getter and setter methods associated with a property are propertyName and setPropertyName: respectively—for example, given a property “foo”, the accessors would be foo and setFoo:" That has given me a clue that I've done something wrong here, I'm fairly new to objective C so would appreciate anyone who spends the time to explain this to me. Thanks!

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• Is it possible, in ASP.net, to reference private assembly in a non-virtual subdirectory?

  - by Bago

  Is it possible to reference a private assembly in asp .net from a sub-folder that is not setup as a virtual directory? In other words, my page is setup in ~/subdir, I don't have access to ~/, and I am not an IIS admin. Can I reference a private assembly? How would I do this? I've tried <%@ Assembly Src="/subdir/bin/Assembly.dll % and <%@ Assembly Src="/subdir/bin/Assembly.dll % , but I get the messages "There is no build provider to match the extension .dll" or "Failed to map to path" respectively. Here is my folder structure: / | -subdir | | - Bin | | | *Assembly.dll | | *Default.aspx I've heard that in web.config might do the trick, but when I've tried it, it doesn't seem to work. Furthermore, I've read that only works in the application .config file. (i.e., the one in ~/). Anyhow, I already tried adding the following to web.config: <runtime> <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> <probing privatePath="/subdir/bin" /> <dependentAssembly> <codeBase href="/subdir/bin/Assembly.dll"/> </dependentAssembly> </assemblyBinding> For more background on my problem, I am simply using a shared host, all I have is access to is that subdirectory, and I am trying to use fckeditor.

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• Is it possible, in ASP .net, to reference private assembly in a non-virtual subdirectory?

  - by Bago

  Is it possible to reference a private assembly in asp .net from a sub-folder that is not setup as a virtual directory? In other words, my page is setup in ~/subdir, I don't have access to ~/, and I am not an IIS admin. Can I reference a private assembly? How would I do this? I've tried <%@ Assembly Src="/subdir/bin/Assembly.dll % and <%@ Assembly Src="/subdir/bin/Assembly.dll % , but I get the messages "There is no build provider to match the extension .dll" or "Failed to map to path" respectively. Here is my folder structure: / | -subdir | | - Bin | | | *Assembly.dll | | *Default.aspx I've heard that in web.config might do the trick, but when I've tried it, it doesn't seem to work. Furthermore, I've read that only works in the application .config file. (i.e., the one in ~/). Anyhow, I already tried adding the following to web.config: <runtime> <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> <probing privatePath="/subdir/bin" /> <dependentAssembly> <codeBase href="/subdir/bin/Assembly.dll"/> </dependentAssembly> </assemblyBinding> For more background on my problem, I am simply using a shared host, all I have is access to is that subdirectory, and I am trying to use fckeditor.

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• How can I output my MySQL data into following structures?

  - by sky

  Here is the question, how can I output MySQL data into format like : userAge, userMid are the column name, table name Users. <script type="text/javascript"> userAge = new Array('21','36','20'), userMid = new Array('liuple','anhu','jacksen'); </script> Which I'll be using later with following code : var html = ' <table class="map-overlay"> <tr> <td class="user">' + '<a class="username" href="/' + **userMid[index]** + '" target="_blank"><img alt="" src="' + getAvatar(signImgList[index], '72x72') + '"></a><br> <a class="username" href="/' + **userMid[index]** + '" target="_blank">' + userNameList[index] + '</a><br> <span class="info">' + **userSex[index]** + ' ' + **userAge[index]** + '?<br> ' + cityList[index] + '</span>' + '</td> <td class="content">' + picString + somethings[index] + '<br> <span class="time">' + timeList[index] + picTips + '</span></td> </tr> </table> '; PS: I Just been told that i coulnt use JSON to output that format, so i have no idea now .< Thanks!

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• C# WinForms populating TreeView from List<myObj>

  - by user743354

  I have this structure of classes: public class L3Message { public int Number { get; set; } public string MessageName { get; set; } public string Device { get; set; } public string Time { get; set; } public string ScramblingCode { get; set; } public List<Parameter> Parameters { get; set; } public L3Message() { Parameters = new List<Parameter>(); } } public class Parameter { public int numOfWhitespaces { get; set; } public string ParameterName { get; set; } public string ParameterValue { get; set; } public Parameter Parent { get; set; } public List<Parameter> SubParameters { get; set; } public Parameter() { SubParameters = new List<Parameter>(); } } So, as return type from one of my Methods I have List of L3Messages (List < L3Message ), and I need to map that to TreeView in WinForms (populate TreeView from that List). If possible, I would like to that in separate thread. How can I achieve that?

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• Stuck on scrolling GtkViewPort to end.

  - by PP

  I am adding one GtkVBox to GtkViewPort. And I am doing scrolling for GtkViewPort based on two Up/Down Buttons. I need to display last item in VBox as we do in Message Chat Screens (Message Chat list displays/adds newest chat message at bottom of the list) i doing exact thing. so for scrolling at the bottom of the GtkViewPort i am doing in the map event call back. GtkAdjustment* adjustment; adjustment = gtk_viewport_get_vadjustment(GTK_VIEWPORT(viewport_list)); gtk_adjustment_set_value(adjustment, gtk_adjustment_get_upper(adjustment)); So this works perfectly fine. it displays newest added widget in Vbox at the end. on some external events I add new Widgets to my VBox and call above code again to display these newly added widgets. on first add it does not scroll at all but on 2nd add to VBOX it scroll upto 2nd last Widget in the list. Why this might be happening. It there another way of scrolling GtkViewPort to the end? Thanks for reading :)

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• Database schema to store AND, OR relation, association

  - by user455387

  Many thanks for your help on this. In order for an entreprise to get a call for tender it must meet certain requirements. For the first example the enterprise must have a minimal class 4, and have qualification 2 in sector 5. Minimal class is always one number. Qualification can be anything (single, or multiple using AND, OR logical operators) I have created tables in order to map each number to it's given name. Now I need to store requirements in the database. minimal class 4 Sector Qualification 5.2 minimal class 2 Sector Qualifications 3.9 and 3.10 minimal class 3 Sector Qualifications 6.1 or 6.3 minimal class 1 Sector Qualifications (3.1 and 3.2) or 5.6 class Domain < ActiveRecord::Base has_many :domain_classes has_many :domain_sectors has_many :sector_qualifications, :through => :domain_sectors end class DomainClass < ActiveRecord::Base belongs_to :domain end class DomainSector < ActiveRecord::Base belongs_to :domain has_many :sector_qualifications end class SectorQualification < ActiveRecord::Base belongs_to :domain_sector end create_table "domains", :force => true do |t| t.string "name" end create_table "domain_classes", :force => true do |t| t.integer "number" t.integer "domain_id" end create_table "domain_sectors", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_id" end create_table "sector_qualifications", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_sector_id" end

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• java /TableModel of Objects/Update Object"

  - by Tomás Ó Briain

  I've a collection of Stock objects that I'm updating about 10/15 variables for in real-time. I'm accessing each Stock by its ID in the collection. I'm also trying to display this in a JTable and have implemented an AbstractTablemodel. It's not working too well. I've a RowMap that I add each ID to as Stocks are added to the TableModel. To update the prices and variables of all the stocks in the TableModel, I want to send a Stock object to an updateModel(Stock s) method. I can find the relevant row by searching the map, but how do I handle this nicely, so I don't have to start iterating through table columns and comparing the values of the cells to the variables of the object to see whether there are any differences?? Basically, i want to send a Stock object to the TableModel and update cells if there are changes and do nothing if there aren't. Any ideas about how to implement a TableModel that might do this? Any pointeres at all would be appreciated. Thanks.

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• Find messages from certain key till certain key while being able to remove stale keys.

  - by Alfred

  My problem Let's say I add messages to some sort of datastructure: 1. "dude" 2. "where" 3. "is" 4. "my" 5. "car" Asking for messages from index[4,5] should return: "my","car". Next let's assume that after a while I would like to purge old messages because they aren't useful anymore and I want to save memory. Let's say at time x messages[1-3] became stale. I assume that it would be most efficient to just do the deletion once every x seconds. Next my datastructure should contain: 4. "my" 5. "car" My solution? I was thinking of using a concurrentskiplistset or concurrentskiplist map. Also I was thinking of deleting the old messages from inside a newSingleThreadScheduledExecutor. I would like to know how you would implement(efficiently/thread-safe) this or maybe use a library?

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• CodeModel help needed for right-hand singleton.getinstance() assignment.

  - by antarti

  I've been able to generate 99% of what I need with the CodeModel API, but I am stumped here... Using the various "directXX" methods does not add import statements to the generated code, and I can work without the "directXXX" type of methods except for one place in a generated class. Suppose I desire a generated method like: /** * Copies data from this Value-Obj instance, to the returned PERSON instance. * * @return PERSON * */ public PERSON mapVOToPERSON() throws MappingException { Mapper mapper = (com.blah.util.MapperSingleton.getMapperInstance()); return mapper.map(this, PERSON.class); } You can see the right hand of the Mapper assignment in parens. Emitting the entire package+class was the only way I could find to just declare "SomeSingleton.someMethod()" on the right hand side and have the generated code compile. Without the MapperSingleton being added to the object model, there is no import generated... Questions: 1) Is there a way to force an import to be generated? 2) How to declare an expression that gives me the right side of the Mapper assignment within the object model (so that an import of MapperSingleton gets generated. Any help appreciated...

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• Scala XML API: Why allow NodeSeq as attribute values?

  - by Synesso

  It seems attribute values are of type Seq[Node]. scala> <a b="1"/>.attribute("b") res11: Option[Seq[scala.xml.Node]] = Some(1) This means you can assign XML as an attribute value. scala> <a b={<z><x/></z>}/>.attribute("b") res16: Option[Seq[scala.xml.Node]] = Some(<z><x></x></z>) scala> <a b={<z><x/></z>}/>.attribute("b").map(_ \ "x") res17: Option[scala.xml.NodeSeq] = Some(<x></x>) scala> new xml.PrettyPrinter(120, 2).format(<a b={<z><x/></z>}/>) res19: String = <a b="<z><x></x></z>"></a> This seems funky to me. I've never seen XML as attribute values in the real world. Why is it allowed? Why is an attribute value simply not of type String?

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• Shortest Distance From An Array

  - by notyou61

  I have an ajax function which returns the latitudes and longitudes of locations stored in a database. These are returned and placed in an array. A calculation is performed to return their distance from the users current location based on the latitude/longitude. I would like to return only the record with the shortest calculated distance. My code is as follows: Ajax Success // Success success: function (data) { // Obtain Log/Lat navigator.geolocation.getCurrentPosition(function(position) { // Obtain Current Position Lat/Lon glbVar.latitude = position.coords.latitude; glbVar.longitude = position.coords.longitude; // Console Log //console.log('Lat: ' + glbVar.latitude + ' Lon: ' + glbVar.longitude); // Obtain Location Distances for ( var i = 0; i < data.length; i++ ) { // Location Instances var varLocation = data[i]; // Location Distance varLocation.distance = calculateDistance(glbVar.longitude, glbVar.latitude, varLocation.locationLongitude, varLocation.locationLatitude); } // Sort Locations By Distance var sortedData = data.sort(function(a, b) { // Return Locations return a.distance - b.distance; }); // Output Results $.map(sortedData, function(item) { // Obtain Location Distance varLocationsDistance = calculateDistance(glbVar.longitude, glbVar.latitude, item.locationLongitude, item.locationLatitude); // Obtain Location Radius Assignment if (varLocationsDistance <= varLocationRadius) { // Function Return functionReturn = $({locationID : item.locationID + ', Distance : ' + varLocationsDistance + ' m'}); // Return // Function to get the Min value in Array Array.min = function( sortedData ){ functionReturn = Math.min.apply( Math, sortedData ); // console.log(functionReturn); }; } }); }); } The calculateDistance function returns the distance from the users current location and those from the database. The varLocationsDistance <= varLocationRadius "If" statement returns records within a certain distance radius (100 meters), within that statement I would like to return the shortest distance. I am a self taught amateur web developer and as a result may not have provide enough information for an answer, please let me know. Thanks,

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• Getting all the classes in project and their packages from CodeRush extension

  - by drasto

  I've spent some time trying to find a way CodeRush could add using when it finds undeclared element that is in the fact class name with no using added. The solution suggested in this answer to my question (Refactor_resolve) does not work (bugged?). In a process I found out that writing plug-ins for CodeRush is easy, so I decided to code this functionality myself (and share it). I'd only implement a CodeProvider (like in this tutorial). The only thinks I need to do the job are answers to this questions: At the start up of my plugin I need to get a list (set, map, whatever) of all classes and their packages. This means all the classes(interfaces...) and their packages in project, and within all referenced libraries. And I also need to receive updated on this (when user adds reference, creates new class). Can I get this from some CodeRush classes or maybe VS interface available from CodeProvider class? How do I add created CodeProvider to the pop-up that is shown when user hovers over an Issue?

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• how do I create a custom route in rails where I pass the id of an existing Model?

  - by Angela

  I created the following route: map.todo "todo/today", :controller => "todo", :action => "show_date" Originally, the 'show_date' action and associated view would display all the activities associated for that day for all the Campaigns. This ended up being very slow on the database...it would generate roughly 30 records but was still slow. So, I'm thinking of creating a partial that would first list the campaigns separately. If someone clicked on a link associated with campaign_id = 1, I want it to go to the following route: todo/today/campaign/1 Then I would like to know how to know that the '1' is the campaign_id in the controller and then just do its thing. The reason I want a distinct URL is so that I can cache this list. I have to keep going back to this and it's slow. NOTE: It's possibly the problem actually is that I've written the queries in a slow way and sqlite isn't representative of how it will be in production, in which case this work-around is unnecessary, but right now, I need a way to get back to the whole list quickly.

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• Two references to the same domain/entity model

  - by Sbossb

  Problem I want to save the attributes of a model that have changed when a user edits them. Here's what I want to do ... Retrieve edited view model Get domain model and map back updated value Call the update method on repository Get the "old" domain model and compare values of the fields Store the changed values (in JSON) into a table However I am having trouble with step number 4. It seems that the Entity Framework doesn't want to hit the database again to get the model with the old values. It just returns the same entity I have. Attempted Solutions I have tried using the Find() and the SingleOrDefault() methods, but they just return the model I currently have. Example Code private string ArchiveChanges(T updatedEntity) { //Here is the problem! //oldEntity is the same as updatedEntity T oldEntity = DbSet.SingleOrDefault(x => x.ID == updatedEntity.ID); Dictionary<string, object> changed = new Dictionary<string, object>(); foreach (var propertyInfo in typeof(T).GetProperties()) { var property = typeof(T).GetProperty(propertyInfo.Name); //Get the old value and the new value from the models var newValue = property.GetValue(updatedEntity, null); var oldValue = property.GetValue(oldEntity, null); //Check to see if the values are equal if (!object.Equals(newValue, oldValue)) { //Values have changed ... log it changed.Add(propertyInfo.Name, newValue); } } var ser = new System.Web.Script.Serialization.JavaScriptSerializer(); return ser.Serialize(changed); } public override void Update(T entityToUpdate) { //Do something with this string json = ArchiveChanges(entityToUpdate); entityToUpdate.AuditInfo.Updated = DateTime.Now; entityToUpdate.AuditInfo.UpdatedBy = Thread.CurrentPrincipal.Identity.Name; base.Update(entityToUpdate); }

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• How to understand other people's CSS architectures?

  - by John

  I am reasonably good with CSS. However, when working with someone else's CSS, it's difficult for me to see the "bigger picture" in their architecture (but i have no problem when working with a CSS sheet I wrote myself). For example, I have no problems using Firebug to isolate and fix cross browser compatibility issues, or fixing a floating issue, or changing the height on a particular element. But if I'm asked to do something drastic such as, "I want the right sidebars of pages A, B, C and D to have a red border. I want the right side bars of pages E, F and G to have a blue border if and only if the user mouses over", then it takes me time a long time to map out all the CSS inheritance rules to see the "bigger picture". For some reason, I don't encounter the same difficulty with backend code. After a quick debriefing of how a feature works, and a quick inspection of the controller and model code, I will feel comfortable with the architecture. I will think, "it's reasonable to assume that there will be an Employee class that inherits from the Person Class that's used by a Department controller". If I discover inconvenient details that aren't consistent with overall architectural style, I am confident that I can hammer things back in place. With someone else's CSS work, it's much harder for me to see the "relationships" between different classes, and when and how the classes are used. When there are many inheritance rules, I feel overwhelmed. I'm having trouble articulating my question and issues... All I want to know is, why is it so much harder for me to see the bigger picture in someone else's CSS architecture than compared to someone else's business logic layer? **Does it have any thing to do with CSS being a relatively new technology, and there aren't many popular design patterns?

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• sed script to remove file name duplicates

  - by dma_k

  Dear community, I hope the below task will be very easy for sed lovers. I am not sed-guru, but I need to express the following task in sed, as sed is more popular on Linux systems. The input text stream is something which is produced by "make depends" and looks like following: pgm2asc.o: pgm2asc.c ../include/config.h amiga.h list.h pgm2asc.h pnm.h \ output.h gocr.h unicode.h ocr1.h ocr0.h otsu.h barcode.h progress.h box.o: box.c gocr.h pnm.h ../include/config.h unicode.h list.h pgm2asc.h \ output.h database.o: database.c gocr.h pnm.h ../include/config.h unicode.h list.h \ pgm2asc.h output.h detect.o: detect.c pgm2asc.h pnm.h ../include/config.h output.h gocr.h \ unicode.h list.h I need to catch only C++ header files (i.e. ending with .h), make the list unique and print as space-separated list prepending src/ as a path-prefix. This is achieved by the following perl script: make libs-depends | perl -e 'while (<>) { while (/ ([\w\.\/]+?\.h)/g) { $a{$1} = 1; } } print join " ", map { "src/$_" } keys %a;' The output is: src/unicode.h src/pnm.h src/progress.h src/amiga.h src/ocr0.h src/ocr1.h src/otsu.h src/barcode.h src/gocr.h src/../include/config.h src/list.h src/pgm2asc.h src/output.h Please, help to express this in sed.

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• Mixing stored procedures and ORM

  - by Jason

  The company I work for develops a large application which is almost entirely based on stored procedures. We use classic ASP and SQL Server and the major part of the business logic is contained inside those stored procedures. For example, (I know, this is bad...) a single stored procedure can be used for different purposes (insert, update, delete, make some calculations, ...). Most of the time, a stored procedure is used for operations on related tables, but this is not always the case. We are planning to move to ASP.NET in a near future. I have read a lot of posts on StackOverflow recommending that I move the business logic outside the database. The thing is, I have tried to convince the people who takes the decisions at our company and there is nothing I can do to change their mind. Since I want to be able to use the advantages of object-oriented programming, I want to map the tables to actual classes. So far, my solution is to use an ORM (Entity Framework 4 or nHibernate) to avoid mapping the objects manually (mostly to retrieve the data) and use some kind of Data Access Layer to call the existing stored procedures (for saving). I want your advice on this. Do you think it is a good solution? Any ideas?

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• Elegant and 'correct' multiton implementation in Objective C?

  - by submachine

  Would you call this implementation of a multiton in objective-c 'elegant'? I have programmatically 'disallowed' use of alloc and allocWithZone: because the decision to allocate or not allocate memory needs to be done based on a key. I know for sure that I need to work with only two instances, so I'm using 'switch-case' instead of a map. #import "Multiton.h" static Multiton *firstInstance = nil; static Multiton *secondInstance = nil; @implementation Multiton + (Multiton *) sharedInstanceForDirection:(char)direction { return [[self allocWithKey:direction] init]; } + (id) allocWithKey:(char)key { return [self allocWithZone:nil andKey:key]; } + (id)allocWithZone:(NSZone *)zone andKey:(char)key { Multiton **sharedInstance; @synchronized(self) { switch (key) { case KEY_1: sharedInstance = &firstInstance; break; case KEY_2: sharedInstance = &secondInstance; break; default: [NSException raise:NSInvalidArgumentException format:@"Invalid key"]; break; } if (*sharedInstance == nil) *sharedInstance = [super allocWithZone:zone]; } return *sharedInstance; } + (id) allocWithZone:(NSZone *)zone { //Do not allow use of alloc and allocWithZone [NSException raise:NSObjectInaccessibleException format:@"Use allocWithZone:andKey: or allocWithKey:"]; return nil; } - (id) copyWithZone:(NSZone *)zone { return self; } - (id) retain { return self; } - (unsigned) retainCount { return NSUIntegerMax; } - (void) release { return; } - (id) autorelease { return self; } - (id) init { [super init]; return self; } PS: I've not tried out if this works as yet, but its compiling cleanly :)

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• Find if a user is facing a certain Location using Digital Compass by constructing a triangle and usi

  - by Aidan

  Hi Guys, I'm constructing a geolocation based application and I'm trying to figure out a way to make my application realise when a user is facing the direction of the given location (a particular long / lat co-ord). I've done some Googling and checked the SDK but can't really find anything for such a thing. Does anyone know of a way? To clarify Android knows my location, the second location and my orientation. What I want is a way for Android to recognise when my orientation is "facing" the second location (e.g within 90 Degrees or so). We're also assuming that the user is stationary and needs updates every second or so therefore getBearing(); is useless. Alright so we get it has to be math, there appears to be no simple SDK stuff we can use. I did some searching of my own and found Barycentric Co-ords http://www.blackpawn.com/texts/pointinpoly/default.html . So what I'm trying to do now is map the camera's field of view. For Example if the person is facing a certain direction the program should construct a triangle around that field of view, e.g it should make one vertices the phone's position and then go out either side for a set distance making the 2 end points vertices constructing a triangle. If I had this I could then apply Barycentric co-ords to see if the point lay within the newly constructed triangle. Idea's anyone? Example. I could get my current orientation, add 45 to it and go up X distance one side and subtact 45 and go up X distance the other side to find my 2 other points. Though, how would I make android know which way it should go "up" I guess? It would know its baring as this stage so I need it to recognise it's bearing and go out that direction.

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• Heapsort not working in Python for list of strings using heapq module

  - by VSN

  I was reading the python 2.7 documentation when I came across the heapq module. I was interested in the heapify() and the heappop() methods. So, I decided to write a simple heapsort program for integers: from heapq import heapify, heappop user_input = raw_input("Enter numbers to be sorted: ") data = map (int, user_input.split(",")) new_data = [] for i in range(len(data)): heapify(data) new_data.append(heappop(data)) print new_data This worked like a charm. To make it more interesting, I thought I would take away the integer conversion and leave it as a string. Logically, it should make no difference and the code should work as it did for integers: from heapq import heapify, heappop user_input = raw_input("Enter numbers to be sorted: ") data = user_input.split(",") new_data = [] for i in range(len(data)): heapify(data) print data new_data.append(heappop(data)) print new_data Note: I added a print statement in the for loop to see the heapified list. Here's the output when I ran the script: `$ python heapsort.py Enter numbers to be sorted: 4, 3, 1, 9, 6, 2 [' 1', ' 3', ' 2', ' 9', ' 6', '4'] [' 2', ' 3', '4', ' 9', ' 6'] [' 3', ' 6', '4', ' 9'] [' 6', ' 9', '4'] [' 9', '4'] ['4'] [' 1', ' 2', ' 3', ' 6', ' 9', '4']` The reasoning I applied was that since the strings are being compared, the tree should be the same if they were numbers. As is evident, the heapify didn't work correctly after the third iteration. Could someone help me figure out if I am missing something here? I'm running Python 2.4.5 on RedHat 3.4.6-9. Thanks, VSN

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