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  • Problems uploading different file types in codeigniter

    - by Drew
    Below is my script that i'm using to upload different files. All the solutions I've found deal only with multiple image uploads. I am totally stumped for a solution on this. Can someone tell me what it is i'm supposed to be doing to upload different files in the same form? Thanks function do_upload() { $config['upload_path'] = './uploads/nav'; $config['allowed_types'] = 'gif|jpg|png'; $config['max_size'] = '2000'; $this->load->library('upload', $config); if ( ! $this->upload->do_upload('userfile')) { $error = array('error' => $this->upload->display_errors()); return $error; } else { $soundfig['upload_path'] = './uploads/nav'; $soundfig['allowed_types'] = 'mp3|wav'; $this->load->library('upload', $soundfig); if ( ! $this->upload->do_upload('soundfile')) { $error = array('error' => $this->upload->display_errors()); return $error; } else { $data = $this->upload->data('userfile'); $sound = $this->upload->data('soundfile'); $full_path = 'uploads/nav/' . $data['file_name']; $sound_path = 'uploads/nav/' . $sound['file_name']; if($this->input->post('active') == '1'){ $active = '1'; }else{ $active = '0'; } $spam = array( 'image_url' => $full_path, 'sound' => $sound_path, 'active' => $active, 'url' => $this->input->post('url') ); $id = $this->input->post('id'); $this->db->where('id', $id); $this->db->update('NavItemData', $spam); return true; } } } Here is my form: <?php echo form_open_multipart('upload/do_upload');?> <?php if(isset($buttons)) : foreach($buttons as $row) : ?> <h2><?php echo $row->name; ?></h2> <input type="file" name="userfile" size="20" /><br /> <input type="file" name="soundfile" size="20" /> <input type="hidden" name="oldfile" value="<?php echo $row->image_url; ?>" /> <input type="hidden" name="id" value="<?php echo $row->id; ?>" /> <br /><br /> <label>Url: </label><input type="text" name="url" value="<?php echo $row->url; ?>" /><br /> <input type="checkbox" name="active" value="1" <?php if($row->active == '1') { echo 'checked'; } ?> /><br /><br /> <input type="submit" value="submit" /> </form> <?php endforeach; ?> <?php endif; ?>

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  • Which to use, XMP or RDF?

    - by zotty
    What's the difference between RDF and XMP? From what I can tell, XMP is derived from RDF... so what does it offer that RDF doesn't? My particular situation is this: I've got some images which need tagging with details of how an experiment was performed, and what sort of data analysis has been performed on the images. A colleague of mine is pushing for XMP, but he's thinking of the images as photos - they're not really, they're just bits of data. From what I've seen (mainly by opening images in notepad++) the XMP data looks very similar to RDF - even so far as using RDF in the tag names (e.g. <rdf:Seq>). I'd like this data to be usable by other people who use similar instruments for similar experiments, so creating a mini standard (schema?) seems like the way to go. Apologies for the lack of fundemental understanding - I'm a Doctor, not a programmer! If it makes any difference, the language of choice will be C#. Edit for more information: First off, thanks for the excellent replies - thinking of XMP as a vocabulary for RDF makes things a lot clearer. The sort of data I'll be storing wont be avaliable in any of the pre-defined sets. It'll detail experimental set ups, locations and results. I think using RDF is the way to go.

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  • Single Responsibility Principle vs Anemic Domain Model anti-pattern

    - by Niall Connaughton
    I'm in a project that takes the Single Responsibility Principle pretty seriously. We have a lot of small classes and things are quite simple. However, we have an anemic domain model - there is no behaviour in any of our model classes, they are just property bags. This isn't a complaint about our design - it actually seems to work quite well During design reviews, SRP is brought out whenever new behaviour is added to the system, and so new behaviour typically ends up in a new class. This keeps things very easily unit testable, but I am perplexed sometimes because it feels like pulling behaviour out of the place where it's relevant. I'm trying to improve my understanding of how to apply SRP properly. It seems to me that SRP is in opposition to adding business modelling behaviour that shares the same context to one object, because the object inevitably ends up either doing more than one related thing, or doing one thing but knowing multiple business rules that change the shape of its outputs. If that is so, then it feels like the end result is an Anemic Domain Model, which is certainly the case in our project. Yet the Anemic Domain Model is an anti-pattern. Can these two ideas coexist? EDIT: A couple of context related links: SRP - http://www.objectmentor.com/resources/articles/srp.pdf Anemic Domain Model - http://martinfowler.com/bliki/AnemicDomainModel.html I'm not the kind of developer who just likes to find a prophet and follow what they say as gospel. So I don't provide links to these as a way of stating "these are the rules", just as a source of definition of the two concepts.

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  • Some Async Socket Code - Help with Garbage Collection?

    - by divinci
    Hi all, I think this question is really about my understanding of Garbage collection and variable references. But I will go ahead and throw out some code for you to look at. // Please note do not use this code for async sockets, just to highlight my question // SocketTransport // This is a simple wrapper class that is used as the 'state' object // when performing Async Socket Reads/Writes public class SocketTransport { public Socket Socket; public byte[] Buffer; public SocketTransport(Socket socket, byte[] buffer) { this.Socket = socket; this.Buffer = buffer; } } // Entry point - creates a SocketTransport, then passes it as the state // object when Asyncly reading from the socket. public void ReadOne(Socket socket) { SocketTransport socketTransport_One = new SocketTransport(socket, new byte[10]); socketTransport_One.Socket.BeginRecieve ( socketTransport_One.Buffer, // Buffer to store data 0, // Buffer offset 10, // Read Length SocketFlags.None // SocketFlags new AsyncCallback(OnReadOne), // Callback when BeginRead completes socketTransport_One // 'state' object to pass to Callback. ); } public void OnReadOne(IAsyncResult ar) { SocketTransport socketTransport_One = ar.asyncState as SocketTransport; ProcessReadOneBuffer(socketTransport_One.Buffer); // Do processing // New Read // Create another! SocketTransport (what happens to first one?) SocketTransport socketTransport_Two = new SocketTransport(socket, new byte[10]); socketTransport_Two.Socket.BeginRecieve ( socketTransport_One.Buffer, 0, 10, SocketFlags.None new AsyncCallback(OnReadTwo), socketTransport_Two ); } public void OnReadTwo(IAsyncResult ar) { SocketTransport socketTransport_Two = ar.asyncState as SocketTransport; .............. So my question is: The first SocketTransport to be created (socketTransport_One) has a strong reference to a Socket object (lets call is ~SocketA~). Once the async read is completed, a new SocketTransport object is created (socketTransport_Two) also with a strong reference to ~SocketA~. Q1. Will socketTransport_One be collected by the garbage collector when method OnReadOne exits? Even though it still contains a strong reference to ~SocketA~ Thanks all!

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  • F# Seq.initInfinite giving StackOverflowException

    - by TrueWill
    I'm learning F#, and I am having trouble understanding why this crashes. It's an attempt to solve Project Euler problem 2. let rec fibonacci n = if n = 1 then 1 elif n = 2 then 2 else fibonacci (n - 1) + fibonacci (n - 2) let debugfibonacci n = printfn "CALC: %d" n fibonacci n let isEven n = n % 2 = 0 let isUnderLimit n = n < 55 let getSequence = //[1..30] Seq.initInfinite (fun n -> n) |> Seq.map debugfibonacci |> Seq.filter isEven |> Seq.takeWhile isUnderLimit Seq.iter (fun x -> printfn "%d" x) getSequence The final version would call a sum function (and would have a higher limit than 55), but this is learning code. As is, this gives a StackOverflowException. However, if I comment in the [1..30] and comment out the Seq.initInfinite, I get: CALC: 1 CALC: 2 2 CALC: 3 CALC: 4 CALC: 5 8 CALC: 6 CALC: 7 CALC: 8 34 CALC: 9 CALC: 10 CALC: 11 It appears to be generating items on demand, as I would expect in LINQ. So why does it blow up when used with initInfinite?

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  • Lazy Sequences that "Look Ahead" for Project Euler Problem 14

    - by ivar
    I'm trying to solve Project Euler Problem 14 in a lazy way. Unfortunately, I may be trying to do the impossible: create a lazy sequence that is both lazy, yet also somehow 'looks ahead' for values it hasn't computed yet. The non-lazy version I wrote to test correctness was: (defn chain-length [num] (loop [len 1 n num] (cond (= n 1) len (odd? n) (recur (inc len) (+ 1 (* 3 n))) true (recur (inc len) (/ n 2))))) Which works, but is really slow. Of course I could memoize that: (def memoized-chain (memoize (fn [n] (cond (= n 1) 1 (odd? n) (+ 1 (memoized-chain (+ 1 (* 3 n)))) true (+ 1 (memoized-chain (/ n 2))))))) However, what I really wanted to do was scratch my itch for understanding the limits of lazy sequences, and write a function like this: (def lazy-chain (letfn [(chain [n] (lazy-seq (cons (if (odd? n) (+ 1 (nth lazy-chain (dec (+ 1 (* 3 n))))) (+ 1 (nth lazy-chain (dec (/ n 2))))) (chain (+ n 1)))))] (chain 1))) Pulling elements from this will cause a stack overflow for n2, which is understandable if you think about why it needs to look 'into the future' at n=3 to know the value of the tenth element in the lazy list because (+ 1 (* 3 n)) = 10. Since lazy lists have much less overhead than memoization, I would like to know if this kind of thing is possible somehow via even more delayed evaluation or queuing?

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  • gcc, strict-aliasing, and horror stories

    - by Joseph Quinsey
    In http://stackoverflow.com/questions/2906365/gcc-strict-aliasing-and-casting-through-a-union I asked whether anyone had encountered problems with union punning through pointers. So far, the answer seems to be No. This question is broader: do you have any horror stories about gcc and strict-aliasing? Background: Quoting from AndreyT's answer in http://stackoverflow.com/questions/2771023/c99-strict-aliasing-rules-in-c-gcc/2771041#2771041: "Strict aliasing rules are rooted in parts of the standard that were present in C and C++ since the beginning of [standardized] times. The clause that prohibits accessing object of one type through a lvalue of another type is present in C89/90 (6.3) as well as in C++98 (3.10/15). ... It is just that not all compilers wanted (or dared) to enforce it or rely on it." Well, gcc is now daring to do so, with its -fstrict-aliasing switch. And this has caused some problems. See, for example, the excellent article http://davmac.wordpress.com/2009/10/ about a Mysql bug, and the equally excellent discussion in http://cellperformance.beyond3d.com/articles/2006/06/understanding-strict-aliasing.html. Some other less-relevant links: http://stackoverflow.com/questions/1225741/performance-impact-of-fno-strict-aliasing http://stackoverflow.com/questions/754929/strict-aliasing http://stackoverflow.com/questions/262379/when-is-char-safe-for-strict-pointer-aliasing http://stackoverflow.com/questions/725138/how-to-detect-strict-aliasing-at-compile-time So to repeat, do you have a horror story of your own? Problems not indicated by -Wstrict-aliasing would, of course, be preferred. And other C compilers are also welcome.

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  • A little confusion about AJAX and inserting into DOM..

    - by Gnee
    I have this working great, but I'd like a deeper understanding of what is actually going on behind the scenes. I am using Jquery's Ajax method to pull 5 blog posts (returning only the title and first photo). A PHP script grabs the blog posts' title and first photo and sticks it in an array and sends it back to my browser as JSON. Upon receiving the JSON object, Jquery grabs the first member of the JSON object and displays it's title and photo. In a gallery I made, using buttons – the user can iterate the 1-5 posts. So the actual AJAX call happens right away, and only once. I am basically using this kind of setup: $('my_div').html(json_obj[i]) and each click does a i++. So jquery is plucking these blog posts from my computers memory, my web browsers cache, or some kind of cache in the Javascript engine? One of the things it's returning is a pretty gnarly animated gif. I just wonder if it constantly running in the background (but not visible), stealing processing cycles...etc. Or Javascript just inserting (say a flash movie) into the DOM, but before hand does nothing but take up a little memory (no processing). Anyway, I'm just curious. If someone is a guru on this, I'd love to hear your take. THanks!!

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  • Does Perl auto-vivify variables used as references in subroutine calls?

    - by FM
    I've declared 2010 to be the year of higher-order programming, so I'm learning Haskell. The introduction has a slick quick-sort demo, and I thought, "Hey, that's easy to do in Perl". It turned to be easier than I expected. Note that I don't have to worry about whether my partitions ($less and $more) are defined. Normally you can't use an undefined value as an array reference. use strict; use warnings; use List::MoreUtils qw(part); my @data = (5,6,7,4,2,9,10,9,5,1); my @sorted = qsort(@data); print "@sorted\n"; sub qsort { return unless @_; my $pivot = shift @_; my ($less, $more) = part { $_ < $pivot ? 0 : 1 } @_; # Works, even though $less and $more are sometimes undefined. return qsort(@$less), $pivot, qsort(@$more); } As best I can tell, Perl will auto-vivify a variable that you try to use as a reference -- but only if you are passing it to a subroutine. For example, my call to foo() works, but not the attempted print. use Data::Dumper qw(Dumper); sub foo { print "Running foo(@_)\n" } my ($x); print Dumper($x); # Fatal: Can't use an undefined value as an ARRAY reference. # print @$x, "\n"; # But this works. foo(@$x); # Auto-vivification: $x is now []. print Dumper($x); My questions: Am I understanding this behavior correctly? What is the explanation or reasoning behind why Perl does this? Is this behavior explained anywhere in the docs?

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  • ASP.NET MVC Posted date field comes in as 1/1/0001

    - by engil
    Just started working with .NET and MVC(1). I'm having a problem wherein in my add action the entered date for some reason ends up as 1/1/0001 instead of what is entered thus causing a date overflow. In my model, this field ("Added") is is of type datetime and does not allow nulls. In my controller I have: public ActionResult Add() { Instance instance = new Instance() { Added = DateTime.Now, Active = true }; return View(instance); } [AcceptVerbs(HttpVerbs.Post)] public ActionResult Add(Instance instance) { if (ModelState.IsValid) { try { System.Diagnostics.Trace.Write("test"); instanceRepository.Add(instance); instanceRepository.Save(); return RedirectToAction("Details", new { id = instance.InstanceID }); } catch { ModelState.AddRuleViolations(instance.GetRuleViolations()); } } return View(instance); } And in my view I have: <div class="editor-label"> <%= Html.LabelFor(model => model.Added) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Added,String.Format("{0:g}",Model.Added))%> <%= Html.ValidationMessageFor(model => model.Added) %> When I first go to Instances/Add the default value is set correctly, however as soon as I submit the date turns into 1/1/0001 (from my understanding this indicates that it was either null or in an unrecognizable format) When I debug and palce a watch on Request.Form I see the date coming in encoded ie Request.Form {Added=4%2f9%2f2010+8%3a24%3a39+AM} - is this an issue? I know its probably not enough information to make a conlusive determination on why this is failing, but if someone could provide some good debugging tips on how to determine where the submitted date is getting munged I'd really appreciate it.

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  • Monotouch threads, GC, WCF

    - by cvista
    Hi This is a question about best practices i guess but it applies directly to my current MT project. I'm using WCF services to communicate with the server. To do this i do the following: services.MethodToCall(params); and the asynch: services.OnMethodToCallCompleted += delegate{ //do stuff and ting }; This can lead to issues if you're not careful in that variables defined within the scope of the asynch callback can sometimes be cleaned up by the gc and this can cause crashes. So - I am making it a practice to declare these outside of the scope of the callback unless I am 100% sure they are not needed. Now - when doing stuff and ting implies changing the ui - i wrap it all in an InvokeOnMainThread call. I guess wrapping everything in this would slow the main thread down and rubbish the point of having multi threads. Even though I'm being careful about all this i am still getting crashes and I have no idea why! I am certain it has something to do with threads, scope and all that. Now - the only thing I can think of outside of updating the UI that may need to happen inside of InvokeOnMainThread is that I have a singleton 'Database' class. This is based on the version 5 code from this thread http://www.yoda.arachsys.com/csharp/singleton.html So now if the service method returns data that needs to be added/updated to the Database class -I also wrap this inside an InvokeOnMainThread call. Still getting random crashes. So... My question is this: I am new to thick client dev - I'm coming from a web dev perspective where we don't need to worry about threads so much :) Aside from what I have mentioned -are there any other things I should be aware of? Is the above stuff correct? Or am i miss-understanding something? Cheers w://

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  • Move rotating image along Canvas

    - by fatnic
    Hi. I've managed to make an image rotate on my canvas. And I've managed to make an image move along the canvas. My problem now is making it do both. I have got it working but I seems a bit like a hack. I've posted a demo online Here's the code. var cnv = document.getElementById("drawing"); var c = cnv.getContext('2d'); var image = new Image(); image.src = 'images/spaceship.png'; var imgWidth = image.width; var imgHeight = image.height; var i=0; function animate() { c.clearRect(0,0,640,480); c.save(); c.translate(-(imgWidth/2)+i,200); c.rotate(i * Math.PI/180); c.translate(-(imgWidth/2),-(imgHeight/2)); c.drawImage(image, 0, 0); c.restore(); (i==640+imgWidth) ? i=0: i+=2; }; setInterval(animate, 1); I think my problem is I'm not understanding the translate() method properly. Is this the correct way to do it or am I competely way off?

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  • Long running transactions with Spring and Hibernate?

    - by jimbokun
    The underlying problem I want to solve is running a task that generates several temporary tables in MySQL, which need to stay around long enough to fetch results from Java after they are created. Because of the size of the data involved, the task must be completed in batches. Each batch is a call to a stored procedure called through JDBC. The entire process can take half an hour or more for a large data set. To ensure access to the temporary tables, I run the entire task, start to finish, in a single Spring transaction with a TransactionCallbackWithoutResult. Otherwise, I could get a different connection that does not have access to the temporary tables (this would happen occasionally before I wrapped everything in a transaction). This worked fine in my development environment. However, in production I got the following exception: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction This happened when a different task tried to access some of the same tables during the execution of my long running transaction. What confuses me is that the long running transaction only inserts or updates into temporary tables. All access to non-temporary tables are selects only. From what documentation I can find, the default Spring transaction isolation level should not cause MySQL to block in this case. So my first question, is this the right approach? Can I ensure that I repeatedly get the same connection through a Hibernate template without a long running transaction? If the long running transaction approach is the correct one, what should I check in terms of isolation levels? Is my understanding correct that the default isolation level in Spring/MySQL transactions should not lock tables that are only accessed through selects? What can I do to debug which tables are causing the conflict, and prevent those tables from being locked by the transaction?

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  • Data Annotations on ViewModels or Domain Objects

    - by Ahmad
    Where would data annotations be more suitable: ViewModels or Domain Objects or Both I am struggling to decide where these will be more suited. I have not as yet fully utilized them but this question came to mind. From most of the examples I have seen, they are generally placed on Models and simply use the required attributes for validation using ModelState.IsValid. I have also seen another question on SO where the use of data annotations alone is not sufficient and advocate. Option 1 - I will still need to validate again in my service layer. ( I think that my service layer should be complete and this include validation, since its planned to be used elsewhere) Option 2 - How will I then get the benefits of the built in validation both client and server side. Option 3 - there will be a repetition of validation logic, however I was wondering if one could use a MetaData class approach that can be used for both ViewModels and Domain Objects. ( This is completely of the top of my head, so it may be nonsensical) I wonder if this question even makes sense. If not, can someone please help in understanding this better. Have I completely misunderstood the use of data annotations?

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  • when an autoreleased object is actually released?

    - by psebos
    Hi, I am new in objective-c and I am trying to understand memory management to get it right. After reading the excellent Memory Management Programming Guide for Cocoa by apple my only concern is when actually an autoreleased object is released in an iphone/ipod application. My understanding is at the end of a run loop. But what defines a run loop in the application? So I was wondering whether the following piece of code is right. Assume an object @implementation Test - (NSString *) functionA { NSString *stringA; stringA = [[NSString alloc] initWithString:@"Hello" autorelease] return stringA; } - (NSString *) functionB { NSString *stringB; stringB = [self functionA]; return stringB; } - (NSString *) functionC { NSString *stringC; stringC = [self functionB]; return stringC; } - (void)viewDidLoad { [super viewDidLoad]; (NSString *) p = [self functionC]; NSLog(@"string is %@",p); } @end Is this code valid? From the apple text I understand that the NSString returned from functionA is valid in the scope of functionB. I am not sure whether it is valid in functionC and in viewDidLoad. Thanks!

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  • Call Python From PHP And Get Return Code

    - by seaboy
    Hello everyone, I am calling a python script from PHP. The python program has to return some value according to the arguments passed to it. Here is a sample python program, which will give you a basic idea of what i am doing currently: #!/usr/bin/python import sys #get the arguments passed argList = sys.argv #Not enough arguments. Exit with a value of 1. if len(argList) < 3: #Return with a value of 1. sys.exit(1) arg1 = argList[1] arg2 = argList[2] #Check arguments. Exit with the appropriate value. if len(arg1) > 255: #Exit with a value of 4. sys.exit(4) if len(arg2) < 2: #Exit with a value of 8. sys.exit(8) #Do further coding using the arguments------ #If program works successfully, exit with a value of 0 As you can see from the above code, my basic aim is for the python program to return some values (0,1,4,8 etc) depending on the arguments. And then the calling PHP program to access these returned values and do the appropriate operation. Currently i have used "sys.exit(n)", for that purpose. Am i right in using sys.exit, or do I need to use something else? And also what method exists in PHP so that I can access the return code from python? Sorry for the long question, but hopefully it will help in you understanding my dilemma Thanks a ton

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  • Using Python to get a CSV output for the following example.

    - by Az
    Hi there, I'm back again with my ongoing saga of Student-Project Allocation questions. Thanks to Moron (who does not match his namesake) I've got a bit of direction for an evaluation portion of my project. Going with the idea of the Assignment Problem and Hungarian Algorithm I would like to express my data in the form of a .csv file which would end up looking like this in spreadsheet form. This is based on the structure I saw here. | | Project 1 | Project 2 | Project 3 | |----------|-----------|-----------|-----------| |Student1 | | 2 | 1 | |----------|-----------|-----------|-----------| |Student2 | 1 | 2 | 3 | |----------|-----------|-----------|-----------| |Student3 | 1 | 3 | 2 | |----------|-----------|-----------|-----------| To make it less cryptic: the rows are the Students/Agents and the columns represent Projects/Task. Obviously ONE project can be assigned to ONE student. That, in short, is what my project is about. The fields represent the preference weights the students have placed upon the projects (ranging from 1 to 10). If blank, that student does not want that project and there's no chance of him/her being assigned such. Anyway, my data is stored within dictionaries. Specifically the students and projects dictionaries such that: students[student_id] = Student(student_id, student_name, alloc_proj, alloc_proj_rank, preferences) where preferences is in the form of a dictionary such that preferences[rank] = {project_id} and projects[project_id] = Project(project_id, project_name) I'm aware that sorted(students.keys()) will give me a sorted list of all the student IDs which will populate the row labels and sorted(projects.keys()) will give me the list I need to populate the column labels. Thus for each student, I'd go into their preferences dictionary and match the applicable projects to ranks. I can do that much. Where I'm failing is understanding how to create a .csv file. Any help, pointers or good tutorials will be highly appreciated.

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  • Android GPS cloud of confusion!

    - by Anthony Forloney
    I am trying to design my first Android application with the use of GPS. As of right now, I have a drawable button that when clicked, alerts a Toast message of the longitude and latitude. I have tried to use the telnet localhost 5554 and then geo fix #number #number to feed in values but no results display just 0 0. I have also tried DDMS way of sending GPS coordinates and I get the same thing. My question is what exactly is the code equivalent to the geo fix and the DDMS way of sending coordinates. I have used Location, LocationManger and LocationListener but I am not sure which is the right choice. Could anyone explain to me what the code-equivalent just so I can get a better understanding of how to fix my application not working. Code is given, just in case if the error exists with the code @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button button = (Button) findViewById(R.id.track); button.setOnClickListener(this); LocationManager location =(LocationManager)getSystemService(Context.LOCATION_SERVICE); Location loc = location.getLastKnownLocation(location.GPS_PROVIDER); updateWithNewLocation(loc); } private final LocationListener locationListener = new LocationListener() { public void onLocationChanged(Location location) { updateWithNewLocation(location); } private void updateWithNewLocation(Location l) { longitude = l.getLongitude(); latitude = l.getLatitude(); provider = l.getProvider(); } public void onClick(View v) { Toast.makeText(this, "Your location is " + longitude + " and " + latitude + " provided by: " + provider, Toast.LENGTH_SHORT).show(); } }

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  • returning autorelease NSString still causes memory leaks

    - by hookjd
    I have a simple function that returns an NSString after decoding it. I use it a lot throughout my application, and it appears to create a memory leak (according to "leaks" tool) every time I use it. Leaks tells me the problem is on the line where I alloc the NSString that I am going to return, even though I autorelease it. Here is the function: -(NSString *) decodeValue { NSString *newString; newString = [self stringByReplacingOccurrencesOfString:@"#" withString:@"$"]; NSData *stateData = [NSData dataWithBase64EncodedString:newString]; NSString *convertState = [[[NSString alloc] initWithData:stateData encoding:NSUTF8StringEncoding] autorelease]; return convertState; } My understanding of [autorelease] is that it should be used in exactly this way... where I want to hold onto the object just long enough to return it in my function and then let the object be autoreleased later. So I believe I can use this function through code like this without manually releasing anything: NSString *myDecodedString = [myString decodeValue]; But this process is reporting leaks and I don't understand how to change it to avoid the leaks. What am I doing wrong?

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  • What is wrong with accessing DBI directly?

    - by canavanin
    Hi everyone! I'm currently reading Effective Perl Programming (2nd edition). I have come across a piece of code which was described as being poorly written, but I don't yet understand what's so bad about it, or how it should be improved. It would be great if someone could explain the matter to me. Here's the code in question: sub sum_values_per_key { my ( $class, $dsn, $user, $password, $parameters ) = @_; my %results; my $dbh = DBI->connect( $dsn, $user, $password, $parameters ); my $sth = $dbh->prepare( 'select key, calculate(value) from my_table'); $sth->execute(); # ... fill %results ... $sth->finish(); $dbh->disconnect(); return \%results; } The example comes from the chapter on testing your code (p. 324/325). The sentence that has left me wondering about how to improve the code is the following: Since the code was poorly written and accesses DBI directly, you'll have to create a fake DBI object to stand in for the real thing. I have probably not understood a lot of what the book has so far been trying to teach me, or I have skipped the section relevant for understanding what's bad practice about the above code... Well, thanks in advance for your help!

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  • Rails running multiple delayed_job - lock tables

    - by pepernik
    Hey. I use delayed_job for background processing. I have 8 CPU server, MySQL and I start 7 delayed_job processes RAILS_ENV=production script/delayed_job -n 7 start Q1: I'm wondering is it possible that 2 or more delayed_job processes start processing the same process (the same record-row in the database delayed_jobs). I checked the code of the delayed_job plugin but can not find the lock directive in a way it should be. I think each process should lock the database table before executing an UPDATE on lock_by column. They lock the record simply by updating the locked_by field (UPDATE delayed_jobs SET locked_by...). Is that really enough? No locking needed? Why? I know that UPDATE has higher priority than SELECT but I think this does not have the effect in this case. My understanding of the multy-threaded situation is: Process1: Get waiting job X. [OK] Process2: Get waiting jobs X. [OK] Process1: Update locked_by field. [OK] Process2: Update locked_by field. [OK] Process1: Get waiting job X. [Already processed] Process2: Get waiting jobs X. [Already processed] I think in some cases more jobs can get the same information and can start processing the same process. Q2: Is 7 delayed_jobs a good number for 8CPU server? Why yes/not. Thx 10x!

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  • boost::shared_ptr in Objective-C++

    - by John Smith
    This is a better understanding of a question I had earlier. I have the following Objective-C++ object @interface OCPP { MyCppobj * cppobj; } @end @implementation OCPP -(OCPP *) init { cppobj = new MyCppobj; } @end Then I create a completely differently obj which needs to use cppobj in a boost::shared_ptr (I have no choice in this matter, it's part of a huge library which I cannot change) @interface NOBJ -(void) use_cppobj_as_shared_ptr { //get an OCPP obj called occ from somewhere.. //troubling line here } @end I have tried the following and that failed: I tried synthesising cppobj. Then I created a shared_ptr in "troubling line" in the following way: MyCppobj * cpp = [occ cppobj]; bsp = boost::shared_ptr<MyCppobj>(cpp); It works fine first time around. Then I destroy the NOBJ and recreate it. When I for cppobj it's gone. Presumably shared_ptr decided it's no longer needed and did away with it. So I need help. How can I keep cppobj alive? Is there a way to destroy bsp (or it's reference to cppobj) without destroying cppobj?

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  • SVN Serve, Missing a Directory

    - by Ryan Smith
    I'm sure this is an asinine question, and I blame myself for not fully understanding how the SVNSERVE process works. I have an SVN repo, but it needs to be moved to a server within a clients cloud. I did this a while back and ran into the issue of the SVNSERVE.exe process not getting set to the right directory. I have the SVNSERVE.exe process running as a windows service and pointing to the right directory. There are two other repos there that are serving out fine in the same directory. I copied out the new directory just like I did with the others, but I'm getting the error "No repository found". I thought that SVNSERVE just looked at that directory and served out the repositories that were there, but I have had a hard time finding more information about that. I thought it was a Windows permission problem, but I set the whole folder to be full control to EVERYONE, so that's not it. I feel horrible I didn't fully understand this problem the first time I fought it, but it's late on a Sunday night and clients are yelling. Anyone know what I'm missing? Thanks. EDIT: It's specific to the repository. I tested the same process with some of the other repos we have on our server and when I copied them up, they worked just as expected. This bug is breaking me and I wish I could provide more details, but that's all I know. I'm going to try to do an SVN Dump instead of an XCopy and see how that goes. I'll let you know.

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  • Segmentation in Linux : Segmentation & Paging are redundant?

    - by claws
    Hello, I'm reading "Understanding Linux Kernel". This is the snippet that explains how Linux uses Segmentation which I didn't understand. Segmentation has been included in 80 x 86 microprocessors to encourage programmers to split their applications into logically related entities, such as subroutines or global and local data areas. However, Linux uses segmentation in a very limited way. In fact, segmentation and paging are somewhat redundant, because both can be used to separate the physical address spaces of processes: segmentation can assign a different linear address space to each process, while paging can map the same linear address space into different physical address spaces. Linux prefers paging to segmentation for the following reasons: Memory management is simpler when all processes use the same segment register values that is, when they share the same set of linear addresses. One of the design objectives of Linux is portability to a wide range of architectures; RISC architectures in particular have limited support for segmentation. All Linux processes running in User Mode use the same pair of segments to address instructions and data. These segments are called user code segment and user data segment , respectively. Similarly, all Linux processes running in Kernel Mode use the same pair of segments to address instructions and data: they are called kernel code segment and kernel data segment , respectively. Table 2-3 shows the values of the Segment Descriptor fields for these four crucial segments. I'm unable to understand 1st and last paragraph.

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  • Natural problems to solve using closures

    - by m.u.sheikh
    I have read quite a few articles on closures, and, embarassingly enough, I still don't understand this concept! Articles explain how to create a closure with a few examples, but I don't see any point in paying much attention to them, as they largely look contrived examples. I am not saying all of them are contrived, just that the ones I found looked contrived, and I dint see how even after understanding them, I will be able to use them. So in order to understand closures, I am looking at a few real problems, that can be solved very naturally using closures. For instance, a natural way to explain recursion to a person could be to explain the computation of n!. It is very natural to understand a problem like computing the factorial of a number using recursion. Similarly, it is almost a no-brainer to find an element in an unsorted array by reading each element, and comparing with the number in question. Also, at a different level, doing Object-oriented programming also makes sense. So I am trying to find a number of problems that could be solved with or without closures, but using closures makes thinking about them and solving them easier. Also, there are two types to closures, where each call to a closure can create a copy of the environment variables, or reference the same variables. So what sort of problems can be solved more naturally in which of the closure implementations?

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