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• How can I change the VisualState in a View from the ViewModel?

  - by Decker

  I'm new to WPF and MVVM. I think this is a simple question. My ViewModel is performing an asynch call to obtain data for a DataGrid which is bound to an ObservableCollection in the ViewModel. When the data is loaded, I set the proper ViewModel property and the DataGrid displays the data with no problem. However, I want to introduce a visual cue for the user that the data is loading. So, using Blend, I added this to my markup: <VisualStateManager.VisualStateGroups> <VisualStateGroup x:Name="LoadingStateGroup"> <VisualState x:Name="HistoryLoading"> <Storyboard> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="HistoryGrid"> <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Hidden}"/> </ObjectAnimationUsingKeyFrames> </Storyboard> </VisualState> <VisualState x:Name="HistoryLoaded"> <Storyboard> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="WorkingStackPanel"> <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Hidden}"/> </ObjectAnimationUsingKeyFrames> </Storyboard> </VisualState> </VisualStateGroup> </VisualStateManager.VisualStateGroups> I think I know how to change the state in my code-behind (something similar to this): VisualStateManager.GoToElementState(LayoutRoot, "HistoryLoaded", true); However, the place where I want to do this is in the I/O completion method of my ViewModel which does not have a reference to it's corresponding View. How would I accomplish this using the MVVM pattern?

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• Validation L2S question

  - by user158020

  This may be a bit winded because I am new to wpf. I have created a partial class for an entity in my L2S class that is primarily used for validation. It implements the onchanging and onvalidate methods. I am trying to use the MVVM pattern, and in a window/view I have set the datacontext in the xaml: <Window.DataContext> <vm:StartViewModel /> </Window.DataContext> when a user leaves a required field in the view blank, the onchanging event of the partial class is fired when I close the form, not when I save the data. So, if a user leaves the textbox blank, the old value is retained and the onchaging method is fired, but I have no idea how to alert the user of the resulting error. here is my onchanging code in the partial class: partial void Ondocument_titleChanging(string value) { if (value.Length == 0) throw new Exception("Document title is required."); if (value.Length > 256) throw new Exception("Document title cannot be longer than 256 characters."); } throwing an exception doesn't notify the user of the error. it just allows the form to close and rejects the changes to the textbox. hope this makes sense... edit: this example was taken from Scott Guthries article here: http://aspalliance.com/1427_LINQ_to_SQL_Part_5__Binding_UI_using_the_ASPLinqDataSource_Control.5

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• JSF how to temporary disable validators to save draft

  - by Swiety

  I have a pretty complex form with lots of inputs and validators. For the user it takes pretty long time (even over an hour) to complete that, so they would like to be able to save the draft data, even if it violates rules like mandatory fields being not typed in. I believe this problem is common to many web applications, but can't find any well recognised pattern how this should be implemented. Can you please advise how to achieve that? For now I can see the following options: use of immediate=true on "Save draft" button doesn't work, as the UI data would not be stored on the bean, so I wouldn't be able to access it. Technically I could find the data in UI component tree, but traversing that doesn't seem to be a good idea. remove all the fields validation from the page and validate the data programmaticaly in the action listener defined for the form. Again, not a good idea, form is really complex, there are plenty of fields so validation implemented this way would be very messy. implement my own validators, that would be controlled by some request attribute, which would be set for standard form submission (with full validation expected) and would be unset for "save as draft" submission (when validation should be skipped). Again, not a good solution, I would need to provide my own wrappers for all validators I am using. But as you see no one is really reasonable. Is there really no simple solution to the problem?

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• PHP: What is an efficient way to parse a text file containing very long lines?

  - by Shaun

  I'm working on a parser in php which is designed to extract MySQL records out of a text file. A particular line might begin with a string corresponding to which table the records (rows) need to be inserted into, followed by the records themselves. The records are delimited by a backslash and the fields (columns) are separated by commas. For the sake of simplicity, let's assume that we have a table representing people in our database, with fields being First Name, Last Name, and Occupation. Thus, one line of the file might be as follows [People] = "\Han,Solo,Smuggler\Luke,Skywalker,Jedi..." Where the ellipses (...) could be additional people. One straightforward approach might be to use fgets() to extract a line from the file, and use preg_match() to extract the table name, records, and fields from that line. However, let's suppose that we have an awful lot of Star Wars characters to track. So many, in fact, that this line ends up being 200,000+ characters/bytes long. In such a case, taking the above approach to extract the database information seems a bit inefficient. You have to first read hundreds of thousands of characters into memory, then read back over those same characters to find regex matches. Is there a way, similar to the Java String next(String pattern) method of the Scanner class constructed using a file, that allows you to match patterns in-line while scanning through the file? The idea is that you don't have to scan through the same text twice (to read it from the file into a string, and then to match patterns) or store the text redundantly in memory (in both the file line string and the matched patterns). Would this even yield a significant increase in performance? It's hard to tell exactly what PHP or Java are doing behind the scenes.

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• Decoupling the view, presentation and ASP.NET Web Forms

  - by John Leidegren

  I have an ASP.NET Web Forms page which the presenter needs to populate with controls. This interaction is somewhat sensitive to the page-life cycle and I was wondering if there's a trick to it, that I don't know about. I wanna be practical about the whole thing but not compromise testability. Currently I have this: public interface ISomeContract { void InstantiateIn(System.Web.UI.Control container); } This contract has a dependency on System.Web.UI.Control and I need that to be able to do things with the ASP.NET Web Forms programming model. But neither the view nor the presenter may have knowledge about ASP.NET server controls. How do I get around this? How can I work with the ASP.NET Web Forms programming model in my concrete views without taking a System.Web.UI.Control dependency in my contract assemblies? To clarify things a bit, this type of interface is all about UI composition (using MEF). It's known through-out the framework but it's really only called from within the concrete view. The concrete view is still the only thing that knows about ASP.NET Web Forms. However those public methods that say InstantiateIn(System.Web.UI.Control) exists in my contract assemblies and that implies a dependency on ASP.NET Web Forms. I've been thinking about some double dispatch mechanism or even visitor pattern to try and work around this.

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• Add child to existing parent record in entity framework.

  - by Shawn Mclean

  My relationship between the parent and child is that they are connected by an edge. It is similiar to a directed graph structure. DAL: public void SaveResource(Resource resource) { context.AddToResources(resource); //Should also add children. context.SaveChanges(); } public Resource GetResource(int resourceId) { var resource = (from r in context.Resources .Include("ToEdges").Include("FromEdges") where r.ResourceId == resourceId select r).SingleOrDefault(); return resource; } Service: public void AddChildResource(int parentResourceId, Resource childResource) { Resource parentResource = repository.GetResource(parentResourceId); ResourceEdge inEdge = new ResourceEdge(); inEdge.ToResource = childResource; parentResource.ToEdges.Add(inEdge); repository.SaveResource(parentResource); } Error: An object with the same key already exists in the ObjectStateManager. The existing object is in the Unchanged state. An object can only be added to the ObjectStateManager again if it is in the added state. Image: I have been told this is the sequence in submitting a child to an already existing parent: Get parent - Attach Child to parent - submit parent. That is the sequence I used. The code above is extracted from an ASP.NET MVC 2 application using the repository pattern.

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• Resolve php endless recursion issue

  - by Matt

  Hey all, I'm currently running into an endless recursion situation. I'm implementing a message service that calls various object methods.. it's quite similar to observer pattern.. Here's whats going on: Dispatcher.php class Dispatcher { ... public function message($name, $method) { // Find the object based on the name $object = $this->findObjectByName($name); // Slight psuedocode.. for ease of example if($this->not_initialized($object)) $object = new $object(); // This is where it locks up. } return $object->$method(); ... } class A { function __construct() { $Dispatcher->message("B", "getName"); } public function getName() { return "Class A"; } } class B { function __construct() { // Assume $Dispatcher is the classes $Dispatcher->message("A", "getName"); } public function getName() { return "Class B"; } } It locks up when neither object is initialized. It just goes back and forth from message each other and no one can be initialized. I'm looking for some kind of queue implementation that will make messages wait for each other.. One where the return values still get set. I'm looking to have as little boilerplate code in class A and class B as possible Any help would be immensely helpful.. Thanks! Matt Mueller

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• Rackspace Cloud rewrite jpg causes Session reset

  - by willoller

  This may be the .Net version of this question. I have an image script with the following: ... Response.WriteFile(filename); Response.End(); I am rewriting .jpg files using the following rewrite rule in web.config: <rule name="Image Redirect" stopProcessing="true"> <match url="^product-images/(.*).jpg" /> <conditions> <add input="{REQUEST_URI}" pattern="\.(jp?g|JP?G)$" /> </conditions> <action type="Redirect" redirectType="SeeOther" url="/product-images/ProductImage.aspx?path=product-images/{tolower:{R:1}}.jpg" /> </rule> It basically just rewrites the image path into a query parameter. The problem is that (intermittently of course) Mosso returns a new Asp Session cookie which breaks the whole world. Directly accessing a static .jpg file does not cause this problem. Directly accessing the image script does not cause it either. Only rewriting a .jpg file to the .aspx script causes the Session loss. Things I have tried (From the Rackspace doc How can I bypass the cache?) I added Private cacheability to the image script itself: Response.Cache.SetCacheability(HttpCacheability.Private); I tried adding these cache-disabling nodes to web.config: <staticContent> <clientCache cacheControlMode="DisableCache" /> </staticContent> and <httpProtocol> <customHeaders> <add name="Cache-Control private" value="Cache-Control private" </customHeaders> </httpProtocol> The Solution I need The browser cache cannot be disabled. This means potential solutions involving Cache.SetNoStore() or HttpCacheability.NoCache will not work.

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• Avoiding a fork()/SIGCHLD race condition

  - by larry

  Please consider the following fork()/SIGCHLD pseudo-code. // main program excerpt for (;;) { if ( is_time_to_make_babies ) { pid = fork(); if (pid == -1) { /* fail */ } else if (pid == 0) { /* child stuff */ print "child started" exit } else { /* parent stuff */ print "parent forked new child ", pid children.add(pid); } } } // SIGCHLD handler sigchld_handler(signo) { while ( (pid = wait(status, WNOHANG)) > 0 ) { print "parent caught SIGCHLD from ", pid children.remove(pid); } } In the above example there's a race-condition. It's possible for "/* child stuff */" to finish before "/* parent stuff */" starts which can result in a child's pid being added to the list of children after it's exited, and never being removed. When the time comes for the app to close down, the parent will wait endlessly for the already-finished child to finish. One solution I can think of to counter this is to have two lists: started_children and finished_children. I'd add to started_children in the same place I'm adding to children now. But in the signal handler, instead of removing from children I'd add to finished_children. When the app closes down, the parent can simply wait until the difference between started_children and finished_children is zero. Another possible solution I can think of is using shared-memory, e.g. share the parent's list of children and let the children .add and .remove themselves? But I don't know too much about this. EDIT: Another possible solution, which was the first thing that came to mind, is to simply add a sleep(1) at the start of /* child stuff */ but that smells funny to me, which is why I left it out. I'm also not even sure it's a 100% fix. So, how would you correct this race-condition? And if there's a well-established recommended pattern for this, please let me know! Thanks.

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• ANT propertyfile entry is not resolving to its value

  - by Brian

  I have a value in a properties file that I want to increment while the build is running. The goal is to copy a set of files and append a number to the front of each in order to maintain the order in which they were copied into the directory. I am using the <propertyfile> task as follows: <propertyfile file="jsfiles.properties"> <entry key="file.number" type="int" operation="=" value="10" /> <entry key="file.number" type="int" default="010" operation="+" value="10" pattern="000" /> </propertyfile> Then I do the copy: <copy todir="${js-in.dir}"> <resources> ... </resources> <chainedmapper> <flattenmapper /> <globmapper from="*.js" to="${file.number}-*.js"/> </chainedmapper> </copy> This does exactly what I need it to EXCEPT that instead of the following output: 010-file1.js 020-file2.js 030-file3.js ... I get: ${file.number}-file1.js ${file.number}-file2.js ${file.number}-file3.js ... What am I doing wrong?

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• Recommendations to handle development and deployment of php web apps using shared project code

  - by Exception e

  I am wondering what the best way (for a lone developer) is to develop a project that depends on code of other projects deploy the resulting project to the server I am planning to put my code in svn, and have shared code as a separate project. There are problems with svn:externals which I cannot fully estimate. I've read subversion:externals considered to be an anti-pattern, and How do you organize your version control repository, but there is one special thing with php-projects (and other interpreted source code): there is no final executable resulting from your libraries. External dependencies are thus always on raw source code. Ideally I really want to be able to develop simultaneously on one project and the projects it dependends on. Possible way: Check out a projects' dependency in a sub folder as a working copy of the trunk. Problems I foresee: When you want to deploy a project, you might want to freeze its dependencies, right? The dependency code should not end up as a duplicate in the projects repository, I think. *(update1: I additionally assume svn:ignore will pose problems if I cannot fall back on symlinks, see my comment) I am still looking for suggestions that do not require the use junction points. They are a sort of unsupported hack in winxp, which may break some programs* This leads me to the last part of the question (as one has influence on the other): how do you deploy apps whith such dependencies? I've looked into BuildOut for Python, but it seems to be tightly related to the python ecosystem (resolving and fetching python modules from the web etc). I am very eager to learn about your best practices.

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• Processing command-line arguments in prefix notation in Python

  - by ejm

  I'm trying to parse a command-line in Python which looks like the following: $ ./command -o option1 arg1 -o option2 arg2 arg3 In other words, the command takes an unlimited number of arguments, and each argument may optionally be preceded with an -o option, which relates specifically to that argument. I think this is called a "prefix notation". In the Bourne shell I would do something like the following: while test -n "$1" do if test "$1" = '-o' then option="$2" shift 2 fi # Work with $1 (the argument) and $option (the option) # ... shift done Looking around at the Bash tutorials, etc. this seems to be the accepted idiom, so I'm guessing Bash is optimized to work with command-line arguments this way. Trying to implement this pattern in Python, my first guess was to use pop(), as this is basically a stack operation. But I'm guessing this won't work as well on Python because the list of arguments in sys.argv is in the wrong order and would have to be processed like a queue (i.e. pop from the left). I've read that lists are not optimized for use as queues in Python. So, my ideas are: convert argv to a collections.deque and use popleft(), reverse argv using reverse() and use pop(), or maybe just work with the int list indices themselves. Does anyone know of a better way to do this, otherwise which of my ideas would be best-practise in Python?

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• Hibernate database integrity with multiple java applications

  - by Austen

  We have 2 java web apps both are read/write and 3 standalone java read/write applications (one loads questions via email, one processes an xml feed, one sends email to subscribers) all use hibernate and share a common code base. The problem we have recently come across is that questions loaded via email sometimes overwrite questions created in one of the web apps. We originally thought this to be a caching issue. We've tried turning off the second level cache, but this doesn't make a difference. We are not explicitly opening and closing sessions, but rather let hibernate manage them via Util.getSessionFactory().getCurrentSession(), which thinking about it, may actually be the issue. We'd rather not setup a clustered 2nd level cache at this stage as this creates another layer of complexity and we're more than happy with the level of performance we get from the app as a whole. So does implementing a open-session-in-view pattern in the web apps and manually managing the sessions in the standalone apps sound like it would fix this? Or any other suggestions/ideas please? <property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property> <property name="hibernate.current_session_context_class">thread</property> <property name="hibernate.cache.use_second_level_cache">false</property>

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• Is there a way to use Linq projections with extension methods

  - by Acoustic

  I'm trying to use AutoMapper and a repository pattern along with a fluent interface, and running into difficulty with the Linq projection. For what it's worth, this code works fine when simply using in-memory objects. When using a database provider, however, it breaks when constructing the query graph. I've tried both SubSonic and Linq to SQL with the same result. Thanks for your ideas. Here's an extension method used in all scenarios - It's the source of the problem since everything works fine without using extension methods public static IQueryable<MyUser> ByName(this IQueryable<MyUser> users, string firstName) { return from u in users where u.FirstName == firstName select u; } Here's the in-memory code that works fine var userlist = new List<User> {new User{FirstName = "Test", LastName = "User"}}; Mapper.CreateMap<User, MyUser>(); var result = (from u in userlist select Mapper.Map<User, MyUser>(u)) .AsQueryable() .ByName("Test"); foreach (var x in result) { Console.WriteLine(x.FirstName); } Here's the same thing using a SubSonic (or Linq to SQL or whatever) that fails. This is what I'd like to make work somehow with extension methods... Mapper.CreateMap<User, MyUser>(); var result = from u in new DataClasses1DataContext().Users select Mapper.Map<User, MyUser>(u); var final = result.ByName("Test"); foreach(var x in final) // Fails here when the query graph built. { Console.WriteLine(x.FirstName); } The goal here is to avoid having to manually map the generated "User" object to the "MyUser" domain object- in other words, I'm trying to find a way to use AutoMapper so I don't have this kind of mapping code everywhere a database read operation is needed: var result = from u in new DataClasses1DataContext().Users select new MyUser // Can this be avoided with AutoMapper AND extension methods? { FirstName = v.FirstName, LastName = v.LastName };

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• Wicket: How to implement an IDataProvider/LoadableDetachableModel for indexed lists

  - by cretzel

  What's the best way to implement an IDataProvider and a LoadableDetachable in Wicket for an indexed list? Suppose I have a Customer who has a list of Adresses. class Customer { List adresses; } Now I want to implement a data provider/ldm for the adresses of a customer. I suppose the usual way is an IDataProvider as an inner class which refers to the customer model of the component, like: class AdressDataProvider implements IDataProvider { public Iterator iterator() { Customer c = (Customer)Component.this.getModel(); // somehow get the customer model return c.getAdresses().iterator(); } public IModel model(Object o) { Adress a = (Adress) o; // Return an LDM which loads the adress by id. return new AdressLoadableDetachableModel(a.getId()); } } Question: How would I implement this, when the adress does not have an ID (e.g. it's a Hibernate Embeddable/CollectionOfElements) but can only be identified by its index in the customer.adresses list? How do I keep reference to the owning entity and the index? In fact, I know a solution, but I wonder if there's a common pattern to do this.

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• How to use keyword this in a mouse wrapper in right context in Javascript?

  - by MartyIX

  Hi, I'm trying to write a simple wrapper for mouse behaviour. This is my current code: function MouseWrapper() { this.mouseDown = 0; this.OnMouseDownEvent = null; this.OnMouseUpEvent = null; document.body.onmousedown = this.OnMouseDown; document.body.onmouseup = this.OnMouseUp; } MouseWrapper.prototype.Subscribe = function (eventName, fn) { // Subscribe a function to the event if (eventName == 'MouseDown') { this.OnMouseDownEvent = fn; } else if (eventName == 'MouseUp') { this.OnMouseUpEvent = fn; } else { alert('Subscribe: Unknown event.'); } } MouseWrapper.prototype.OnMouseDown = function () { this.mouseDown = 1; // Fire event $.dump(this.OnMouseDownEvent); if (this.OnMouseDownEvent != null) { alert('test'); this.OnMouseDownEvent(); } } MouseWrapper.prototype.OnMouseUp = function () { this.mouseDown = 0; // Fire event if (this.OnMouseUpEvent != null) { this.OnMouseUpEvent(); } } From what I gathered it seems that in MouseWrapper.prototype.OnMouseUp and MouseWrapper.prototype.OnMouseDown the keyword "this" doesn't mean current instance of MouseWrapper but something else. And it makes sense that it doesn't point to my instance but how to solve the problem? I want to solve the problem properly I don't want to use something dirty. My thinking: * use a singleton pattern (mouse is only one after all) * pass somehow my instance to OnMouseDown/Up - how? Thank you for help!

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• How to receive Email in JEE application

  - by Hank

  Obviously it's not so difficult to send out emails from a JEE application via JavaMail. What I am interested in is the best pattern to receive emails (notification bounces, mostly)? I am not interested in IMAP/POP3-based approaches (polling the inbox) - my application shall react to inbound emails. One approach I could think of would be Keep existing MTA (postfix on linux in my case) - ops team already knows how to configure / operate it For every mail that arrives, spawn a Java app that receives the data and sends it off via JMS. I could do this via an entry in /etc/aliases like myuser: "|/path/to/javahelper" with javahelper calling the Java app, passing STDIN along. MDB (part of JEE application) receives JMS message, parses it, detects bounce message and acts accordingly. Another approach could be Open a listening network socket on port 25 on the JEE application container. Associate a SessionBean with the socket. Bean is part of JEE application and can parse/detect bounces/handle the messages directly. Keep existing MTA as inbound relay, do all its security/spam filtering, but forward emails to myuser (that pass the filter) to the JEE application container, port 25. The first approach I have done before (albeit in a different language/setup). From a performance and (perceived) cleanliness point of view, I think the second approach is better, but it would require me to provide a proper SMTP transport implementation. Also, I don't know if it's at all possible to connect a network socket with a bean... What is your recommendation? Do you have details about the second approach?

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• Ruby Design Problem for SQL Bulk Inserter

  - by crunchyt

  This is a Ruby design problem. How can I make a reusable flat file parser that can perform different data scrubbing operations per call, return the emitted results from each scrubbing operation to the caller and perform bulk SQL insertions? Now, before anyone gets narky/concerned, I have written this code already in a very unDRY fashion. Which is why I am asking any Ruby rockstars our there for some assitance. Basically, everytime I want to perform this logic, I create two nested loops, with custom processing in between, buffer each processed line to an array, and output to the DB as a bulk insert when the buffer size limit is reached. Although I have written lots of helpers, the main pattern is being copy pasted everytime. Not very DRY! Here is a Ruby/Pseudo code example of what I am repeating. lines_from_file.each do |line| line.match(/some regex/).each do |sub_str| # Process substring into useful format # EG1: Simple gsub() call # EG2: Custom function call to do complex scrubbing # and matching, emitting results to array # EG3: Loop to match opening/closing/nested brackets # or other delimiters and emit results to array end # Add processed lines to a buffer as SQL insert statement @buffer << PREPARED INSERT STATEMENT # Flush buffer when "buffer size limit reached" or "end of file" if sql_buffer_full || last_line_reached @dbc.insert(SQL INSERTS FROM BUFFER) @buffer = nil end end I am familiar with Proc/Lambda functions. However, because I want to pass two separate procs to the one function, I am not sure how to proceed. I have some idea about how to solve this, but I would really like to see what the real Rubyists suggest? Over to you. Thanks in advance :D

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• Using git filter-branch to remove commits by their commit message

  - by machineghost

  In our repository we have a convention where every commit message starts with a certain pattern: Redmine #555: SOME_MESSAGE We also do a bit of rebasing to bring in the potential release branch's changes to a specific issue's branch. In other words, I might have branch "foo-555", but before I merge it in to branch "pre-release" I need to get any commits that pre-release has that foo-555 doesn't (so that foo-555 can fast-forward merge in to pre-release). However, because pre-release sometimes changes, we sometimes wind up with situations where you bring in a commit from pre-release, but then that commit later gets removed from pre-release. It's easy to identify commits that came from pre-release, because the number from their commit message won't match the branch number; for instance, if I see "Redmine #123: ..." in my foo-555 branch, I know that its not a commit from my branch. So now the question: I'd like to remove all of the commits that "don't belong" to a branch; in other words, any commit that: Is in my foo-555 branch, but not in the pre-release branch (pre-release..foo-555) Has a commit message that doesn't start with "Redmine #555" but of course "555" will vary from branch to branch. Is there any way to use filter-branch (or any other tool) to accomplish this? Currently the only way I can see to do it is to do go an interactive rebase ("git rebase -i") and manually remove all the "bad" commits.

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• Are monads Writer m and Either e categorically dual?

  - by sdcvvc

  I noticed there is a dual relation between Writer m and Either e monads. If m is a monoid, then unit :: () -> m join :: (m,m) -> m can be used to form a monad: return is composition: a -> ((),a) -> (m,a) join is composition: (m,(m,a)) -> ((m,m),a) -> (m,a) The dual of () is Void (empty type), the dual of product is coproduct. Every type e can be given "comonoid" structure: unit :: Void -> e join :: Either e e -> e in the obvious way. Now, return is composition: a -> Either Void a -> Either e a join is composition: Either e (Either e a) -> Either (Either e e) a -> Either e a and this is the Either e monad. The arrows follow exactly the same pattern. Question: Is it possible to write a single generic code that will be able to perform both as Either e and as Writer m depending on the monoid given?

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• Array of templated structs

  - by Jakub Mertlik

  I have structs templated by int derived from a Base struct. struct Base { int i; double d; }; template< int N > struct Derv : base { static const int mN = N; }; I need to make an array of Derv< N where N can vary for each struct in that array. I know C/C++ does not allow arrays of objects of different types, but is there a way around this? I was thinking of separating the type information somehow (hints like pointers to Base struct or usage of union spring to my mind, but with all of these I don't know how to store the type information of each array element for usage DURING COMPILE TIME). As you can see, the memory pattern of each Derv< N is the same. I need to access the type of each array element for template specialization later in my code. The general aim of this all is to have a compile-time dispatch mechanism without the need to do a runtime "type switch" somewhere in the code. Thank you.

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• How to replace pairs of strings in two files to identical IDs?

  - by Péter Török

  Sorry if the title is not very intelligible, I couldn't come up with anything better. Hopefully my explanation is clear enough: I have a pair of rather large log files with very similar content, except that some strings are different between the two. A couple of examples: UnifiedClassLoader3@19518cc | UnifiedClassLoader3@d0357a JBossRMIClassLoader@13c2d7f | JBossRMIClassLoader@191777e That is, wherever the first file contains UnifiedClassLoader3@19518cc, the second contains UnifiedClassLoader3@d0357a, and so on. [Update] There are about 40 distinct pairs of such identifiers.[/Update] I want to replace these with identical IDs so that I can spot the really important differences between the two files. I.e. I want to replace all occurrences of both UnifiedClassLoader3@19518cc in file1 and UnifiedClassLoader3@d0357a in file2 with UnifiedClassLoader3@1; all occurrences of both JBossRMIClassLoader@13c2d7f in file1 and JBossRMIClassLoader@191777e in file2 with JBossRMIClassLoader@2 etc. Using the Cygwin shell, so far I managed to list all different identifiers occurring in one of the files with grep -o -e 'ClassLoader[0-9]*@[0-9a-f][0-9a-f]*' file1.log | sort | uniq However, now the original order is lost, so I don't know which is the pair of which ID in the other file. With grep -n I can get the line number, so the sort would preserve the order of appearance, but then I can't weed out the duplicate occurrences. Unfortunately grep can not print only the first match of a pattern. I figured I could save the list of identifiers produced by the above command into a file, then iterate over the patterns in the file with grep -n | head -n 1, concatenate the results and sort them again. The result would be something like 2 ClassLoader3@19518cc 137 ClassLoader@13c2d7f 563 ClassLoader3@1267649 ... Then I could (either manually or with sed itself) massage this into a sed command like sed -e 's/ClassLoader3@19518cc/ClassLoader3@2/g' -e 's/ClassLoader@13c2d7f/ClassLoader@137/g' -e 's/ClassLoader3@1267649/ClassLoader3@563/g' file1.log > file1_processed.log and similarly for file2. However, before I start, I would like to verify that my plan is the simplest possible working solution to this. Is there any flaw in this approach? Is there a simpler way?

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• Adroid's DateFormat replacement - missing the format() with FieldPosition

  - by user331244

  Hi, I need to split a date string into pieces and I'm doing it using the public final StringBuffer format (Object object, StringBuffer buffer, FieldPosition field) from the java.text.DateFormat class. However, the implementation of this function is really slow, hence Android has an own implementation in android.text.format.DateFormat. BUT, in my case, I want to extract the different pieces of the date string (year, minute and so on). Since I need to be locale independent, I can not use SimpleDateFormat and custom strings. I do it as follows: Calendar c = ... // find out what field to extract int field = getField(); // Create a date string Field calendarField = DateFormat.Field.ofCalendarField(field); FieldPosition fieldPosition = new FieldPosition(calendarField); StringBuffer label = new StringBuffer(); label = getDateFormat().format(c.getTime(), label, fieldPosition); // Find the piece that we are looking for int beginIndex = fieldPosition.getBeginIndex(); int endIndex = fieldPosition.getEndIndex(); String asString = label.substring(beginIndex, endIndex); For some reason, the format() overload with the FieldPosition argument is not included in the android platform. Any ideas of how to do this in another way? Is there any easy way to tokenize the pattern string? Any other ideas?

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• [Delphi] How would you refactor this code?

  - by Al C

  This hypothetical example illustrates several problems I can't seem to get past, even though I keep trying!! ... Suppose the original code is a long event handler, coded in the UI, triggered when a user clicks a cell in a grid. Expressed as pseudocode it's: if Condition1=true then begin //loop through every cell in row, //if aCell/headerCellValue>1 then //color aCell red end else if Condition2=true then begin //do some other calculation adding cell and headerCell values, and //if some other product>2 then //color the whole row green end else show an error message I look at this and say "Ah, refactor to the strategy pattern! The code will be easier to understand, easier to debug, and easier to later extend!" I get that. And I can easily break the code into multiple procedures. The problem is ultimately scope related. Assume the pseudocode makes extensive use of grid properties, values displayed in cells, maybe even built-in grid methods. How do you move all that to another unit, without referencing the grid component in the UI--which would break all the "rules" about loose coupling that make OOP valuable? ... I'm really looking forward to responses. Thanks, as always -- Al C.

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• Set form MinWidth and MinHeight based on child property

  - by Jon Mitchell

  I'm writing an application in WPF using the MVVM pattern. In my application I've got an IPopupWindowService which I use to create a popup dialog window. So to show a ViewModel in a popup window you'd do something like this: var container = ServiceLocator.Current.GetInstance<IUnityContainer>(); var popupService = container.Resolve<IPopupWindowService>(); var myViewModel = container.Resolve<IMyViewModel>(); popupService.Show((ViewModelBase)myViewModel); This is all well and good. What I want to do is be able to set the MinHeight and MinWidth on the View bound to myViewModel and have the popup window use those settings so that a user cannot make the window smaller than its contents will allow. At the moment when the user shrinks the window the contents stops resizing but the window doesn't. EDIT: I map my Views to my ViewModels in ResourceDictionarys like so: <DataTemplate DataType="{x:Type ViewModels:MyViewModel}"> <Views:MyView /> </DataTemplate> And my popup view looks like this: <Window x:Class="TheCompany.Cubit.Shell.Views.PopupWindowView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" SizeToContent="WidthAndHeight" WindowStartupLocation="CenterOwner"> <DockPanel x:Name="panelContent"> <StackPanel HorizontalAlignment="Right" DockPanel.Dock="Bottom" Orientation="Horizontal" Visibility="{Binding RelativeSource={RelativeSource AncestorType=Window},Path=ButtonPanelVisibility}"> <Button Width="75" IsDefault="True" x:Uid="ViewDialog_AcceptButton" Click="OnAcceptButtonClick" Margin="4">OK</Button> <Button Width="75" IsCancel="True" x:Uid="ViewDialog_CancelButton" Click="OnCancelButtonClick" Margin="0,4,4,4">Cancel</Button> </StackPanel> <ContentPresenter Content="{Binding}" /> </DockPanel>

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