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  • Style: Dot notation vs. message notation in Objective-C 2.0

    - by groundhog
    In Objective-C 2.0 we got the "dot" notation for properties. I've seen various back and forths about the merits of dot notation vs. message notation. To keep the responses untainted I'm not going to respond either way in the question. What is your thought about dot notation vs. message notation for property accessing? Please try to keep it focused on Objective-C - my one bias I'll put forth is that Objective-C is Objective-C, so your preference that it be like Java or JavaScript aren't valid. Valid commentary is to do with technical issues (operation ordering, cast precedence, performance, etc), clarity (structure vs. object nature, both pro and con!), succinctness, etc. Note, I'm of the school of rigorous quality and readability in code having worked on huge projects where code convention and quality is paramount (the write once read a thousand times paradigm).

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  • How to Run Low-Cost Minecraft on a Raspberry Pi for Block Building on the Cheap

    - by Jason Fitzpatrick
    We’ve shown you how to run your own blocktastic personal Minecraft server on a Windows/OSX box, but what if you crave something lighter weight, more energy efficient, and always ready for your friends? Read on as we turn a tiny Raspberry Pi machine into a low-cost Minecraft server you can leave on 24/7 for around a penny a day. Why Do I Want to Do This? There’s two aspects to this tutorial, running your own Minecraft server and specifically running that Minecraft server on a Raspberry Pi. Why would you want to run your own Minecraft server? It’s a really great way to extend and build upon the Minecraft play experience. You can leave the server running when you’re not playing so friends and family can join and continue building your world. You can mess around with game variables and introduce mods in a way that isn’t possible when you’re playing the stand-alone game. It also gives you the kind of control over your multiplayer experience that using public servers doesn’t, without incurring the cost of hosting a private server on a remote host. While running a Minecraft server on its own is appealing enough to a dedicated Minecraft fan, running it on the Raspberry Pi is even more appealing. The tiny little Pi uses so little resources that you can leave your Minecraft server running 24/7 for a couple bucks a year. Aside from the initial cost outlay of the Pi, an SD card, and a little bit of time setting it up, you’ll have an always-on Minecraft server at a monthly cost of around one gumball. What Do I Need? For this tutorial you’ll need a mix of hardware and software tools; aside from the actual Raspberry Pi and SD card, everything is free. 1 Raspberry Pi (preferably a 512MB model) 1 4GB+ SD card This tutorial assumes that you have already familiarized yourself with the Raspberry Pi and have installed a copy of the Debian-derivative Raspbian on the device. If you have not got your Pi up and running yet, don’t worry! Check out our guide, The HTG Guide to Getting Started with Raspberry Pi, to get up to speed. Optimizing Raspbian for the Minecraft Server Unlike other builds we’ve shared where you can layer multiple projects over one another (e.g. the Pi is more than powerful enough to serve as a weather/email indicator and a Google Cloud Print server at the same time) running a Minecraft server is a pretty intense operation for the little Pi and we’d strongly recommend dedicating the entire Pi to the process. Minecraft seems like a simple game, with all its blocky-ness and what not, but it’s actually a pretty complex game beneath the simple skin and required a lot of processing power. As such, we’re going to tweak the configuration file and other settings to optimize Rasbian for the job. The first thing you’ll need to do is dig into the Raspi-Config application to make a few minor changes. If you’re installing Raspbian fresh, wait for the last step (which is the Raspi-Config), if you already installed it, head to the terminal and type in “sudo raspi-config” to launch it again. One of the first and most important things we need to attend to is cranking up the overclock setting. We need all the power we can get to make our Minecraft experience enjoyable. In Raspi-Config, select option number 7 “Overclock”. Be prepared for some stern warnings about overclocking, but rest easy knowing that overclocking is directly supported by the Raspberry Pi foundation and has been included in the configuration options since late 2012. Once you’re in the actual selection screen, select “Turbo 1000MhHz”. Again, you’ll be warned that the degree of overclocking you’ve selected carries risks (specifically, potential corruption of the SD card, but no risk of actual hardware damage). Click OK and wait for the device to reset. Next, make sure you’re set to boot to the command prompt, not the desktop. Select number 3 “Enable Boot to Desktop/Scratch”  and make sure “Console Text console” is selected. Back at the Raspi-Config menu, select number 8 “Advanced Options’. There are two critical changes we need to make in here and one option change. First, the critical changes. Select A3 “Memory Split”: Change the amount of memory available to the GPU to 16MB (down from the default 64MB). Our Minecraft server is going to ruin in a GUI-less environment; there’s no reason to allocate any more than the bare minimum to the GPU. After selecting the GPU memory, you’ll be returned to the main menu. Select “Advanced Options” again and then select A4 “SSH”. Within the sub-menu, enable SSH. There is very little reason to keep this Pi connected to a monitor and keyboard, by enabling SSH we can remotely access the machine from anywhere on the network. Finally (and optionally) return again to the “Advanced Options” menu and select A2 “Hostname”. Here you can change your hostname from “raspberrypi” to a more fitting Minecraft name. We opted for the highly creative hostname “minecraft”, but feel free to spice it up a bit with whatever you feel like: creepertown, minecraft4life, or miner-box are all great minecraft server names. That’s it for the Raspbian configuration tab down to the bottom of the main screen and select “Finish” to reboot. After rebooting you can now SSH into your terminal, or continue working from the keyboard hooked up to your Pi (we strongly recommend switching over to SSH as it allows you to easily cut and paste the commands). If you’ve never used SSH before, check out how to use PuTTY with your Pi here. Installing Java on the Pi The Minecraft server runs on Java, so the first thing we need to do on our freshly configured Pi is install it. Log into your Pi via SSH and then, at the command prompt, enter the following command to make a directory for the installation: sudo mkdir /java/ Now we need to download the newest version of Java. At the time of this publication the newest release is the OCT 2013 update and the link/filename we use will reflect that. Please check for a more current version of the Linux ARMv6/7 Java release on the Java download page and update the link/filename accordingly when following our instructions. At the command prompt, enter the following command: sudo wget --no-check-certificate http://www.java.net/download/jdk8/archive/b111/binaries/jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz Once the download has finished successfully, enter the following command: sudo tar zxvf jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz -C /opt/ Fun fact: the /opt/ directory name scheme is a remnant of early Unix design wherein the /opt/ directory was for “optional” software installed after the main operating system; it was the /Program Files/ of the Unix world. After the file has finished extracting, enter: sudo /opt/jdk1.8.0/bin/java -version This command will return the version number of your new Java installation like so: java version "1.8.0-ea" Java(TM) SE Runtime Environment (build 1.8.0-ea-b111) Java HotSpot(TM) Client VM (build 25.0-b53, mixed mode) If you don’t see the above printout (or a variation thereof if you’re using a newer version of Java), try to extract the archive again. If you do see the readout, enter the following command to tidy up after yourself: sudo rm jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz At this point Java is installed and we’re ready to move onto installing our Minecraft server! Installing and Configuring the Minecraft Server Now that we have a foundation for our Minecraft server, it’s time to install the part that matter. We’ll be using SpigotMC a lightweight and stable Minecraft server build that works wonderfully on the Pi. First, grab a copy of the the code with the following command: sudo wget http://ci.md-5.net/job/Spigot/lastSuccessfulBuild/artifact/Spigot-Server/target/spigot.jar This link should remain stable over time, as it points directly to the most current stable release of Spigot, but if you have any issues you can always reference the SpigotMC download page here. After the download finishes successfully, enter the following command: sudo /opt/jdk1.8.0/bin/java -Xms256M -Xmx496M -jar /home/pi/spigot.jar nogui Note: if you’re running the command on a 256MB Pi change the 256 and 496 in the above command to 128 and 256, respectively. Your server will launch and a flurry of on-screen activity will follow. Be prepared to wait around 3-6 minutes or so for the process of setting up the server and generating the map to finish. Future startups will take much less time, around 20-30 seconds. Note: If at any point during the configuration or play process things get really weird (e.g. your new Minecraft server freaks out and starts spawning you in the Nether and killing you instantly), use the “stop” command at the command prompt to gracefully shutdown the server and let you restart and troubleshoot it. After the process has finished, head over to the computer you normally play Minecraft on, fire it up, and click on Multiplayer. You should see your server: If your world doesn’t popup immediately during the network scan, hit the Add button and manually enter the address of your Pi. Once you connect to the server, you’ll see the status change in the server status window: According to the server, we’re in game. According to the actual Minecraft app, we’re also in game but it’s the middle of the night in survival mode: Boo! Spawning in the dead of night, weaponless and without shelter is no way to start things. No worries though, we need to do some more configuration; no time to sit around and get shot at by skeletons. Besides, if you try and play it without some configuration tweaks first, you’ll likely find it quite unstable. We’re just here to confirm the server is up, running, and accepting incoming connections. Once we’ve confirmed the server is running and connectable (albeit not very playable yet), it’s time to shut down the server. Via the server console, enter the command “stop” to shut everything down. When you’re returned to the command prompt, enter the following command: sudo nano server.properties When the configuration file opens up, make the following changes (or just cut and paste our config file minus the first two lines with the name and date stamp): #Minecraft server properties #Thu Oct 17 22:53:51 UTC 2013 generator-settings= #Default is true, toggle to false allow-nether=false level-name=world enable-query=false allow-flight=false server-port=25565 level-type=DEFAULT enable-rcon=false force-gamemode=false level-seed= server-ip= max-build-height=256 spawn-npcs=true white-list=false spawn-animals=true texture-pack= snooper-enabled=true hardcore=false online-mode=true pvp=true difficulty=1 player-idle-timeout=0 gamemode=0 #Default 20; you only need to lower this if you're running #a public server and worried about loads. max-players=20 spawn-monsters=true #Default is 10, 3-5 ideal for Pi view-distance=5 generate-structures=true spawn-protection=16 motd=A Minecraft Server In the server status window, seen through your SSH connection to the pi, enter the following command to give yourself operator status on your Minecraft server (so that you can use more powerful commands in game, without always returning to the server status window). op [your minecraft nickname] At this point things are looking better but we still have a little tweaking to do before the server is really enjoyable. To that end, let’s install some plugins. The first plugin, and the one you should install above all others, is NoSpawnChunks. To install the plugin, first visit the NoSpawnChunks webpage and grab the download link for the most current version. As of this writing the current release is v0.3. Back at the command prompt (the command prompt of your Pi, not the server console–if your server is still active shut it down) enter the following commands: cd /home/pi/plugins sudo wget http://dev.bukkit.org/media/files/586/974/NoSpawnChunks.jar Next, visit the ClearLag plugin page, and grab the latest link (as of this tutorial, it’s v2.6.0). Enter the following at the command prompt: sudo wget http://dev.bukkit.org/media/files/743/213/Clearlag.jar Because the files aren’t compressed in a .ZIP or similar container, that’s all there is to it: the plugins are parked in the plugin directory. (Remember this for future plugin downloads, the file needs to be whateverplugin.jar, so if it’s compressed you need to uncompress it in the plugin directory.) Resart the server: sudo /opt/jdk1.8.0/bin/java -Xms256M -Xmx496M -jar /home/pi/spigot.jar nogui Be prepared for a slightly longer startup time (closer to the 3-6 minutes and much longer than the 30 seconds you just experienced) as the plugins affect the world map and need a minute to massage everything. After the spawn process finishes, type the following at the server console: plugins This lists all the plugins currently active on the server. You should see something like this: If the plugins aren’t loaded, you may need to stop and restart the server. After confirming your plugins are loaded, go ahead and join the game. You should notice significantly snappier play. In addition, you’ll get occasional messages from the plugins indicating they are active, as seen below: At this point Java is installed, the server is installed, and we’ve tweaked our settings for for the Pi.  It’s time to start building with friends!     

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  • Rails validation "failing when succeeding"

    - by Fredrik
    I have this in my user.rb: attr_accessor :old_password def validate unless password.nil? errors.add_to_base("Old password entered incorrect") unless self.valid_password? old_password end end I have old_password as a a virtual attribute that has to be validated as matching with the current before updating to a new password. My problem is that upon correct entering ( password == password confirmation and self.valid_password? old_password ) an error will yield and pass me back to the form. The strange part is that the data will actually be updated in the database, and it will not on wrong input; although it will yield the very same error ("Old password entered incorrect"). What on earth am I doing wrong?

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  • C# Delegate Invoke Required Issue

    - by Goober
    Scenario I have a C# windows forms application that has a number of processes. These processes run on separate threads and all communicate back to the Main Form class with updates to a log window and a progress bar. I'm using the following code below, which up until now has worked fine, however, I have a few questions. Code delegate void SetTextCallback(string mxID, string text); public void UpdateLog(string mxID, string text) { if (txtOutput.InvokeRequired) { SetTextCallback d = new SetTextCallback(UpdateLog); this.BeginInvoke(d, new object[] { mxID, text }); } else { UpdateProgressBar(text); } } Question Will, calling the above code about 10 times a second, repeatedly, give me errors, exceptions or generally issues?.....Or more to the point, should it give me any of these problems? Occasionally I get OutofMemory Exceptions and the program always seems to crash around this bit of code......

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  • Why would a CSV attachment appear as text in the body?

    - by David
    Hi all I've just implemented some code that emails a bunch of our clients with a CSV file attachment. Some (not many) have got back to us complaining that they don't get an attachment at all - just the CSV text inside the body of the email. Most however are fine. I suspect that it's different mail clients that are treating the attachment differently but I don't have enough info yet to be sure. I'm using .NET's MailMessage class with the Attachment.CreateAttachmentFromString() method. The MIME type I'm specifying for the attachment is text/csv. Anyone have any idea what the heck is going on? Ta muchly David

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  • Unicode issue in Django

    - by Kave
    I seem to have a unicode problem with the deal_instance_name in the Deal model. It says: coercing to Unicode: need string or buffer, __proxy__ found The exception happens on this line: return smart_unicode(self.deal_type.deal_name) + _(u' - Set No.') + str(self.set) The line works if I remove smart_unicode(self.deal_type.deal_name) but why? Back then in Django 1.1 someone had the same problem on Stackoverflow I have tried both the unicode() as well as the new smart_unicode() without any joy. What could I be missing please? class Deal(models.Model): def __init__(self, *args, **kwargs): super(Deal, self).__init__(*args, **kwargs) self.deal_instance_name = self.__unicode__() deal_type = models.ForeignKey(DealType) deal_instance_name = models.CharField(_(u'Deal Name'), max_length=100) set = models.IntegerField(_(u'Set Number')) def __unicode__(self): return smart_unicode(self.deal_type.deal_name) + _(u' - Set No.') + str(self.set) class Meta: verbose_name = _(u'Deal') verbose_name_plural = _(u'Deals') Dealtype: class DealType(models.Model): deal_name = models.CharField(_(u'Deal Name'), max_length=40) deal_description = models.TextField(_(u'Deal Description'), blank=True) def __unicode__(self): return smart_unicode(self.deal_name) class Meta: verbose_name = _(u'Deal Type') verbose_name_plural = _(u'Deal Types')

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  • Collection of MVC CSS files available?

    - by Jaxidian
    Just curious - are there various customized Site.css files (and accompanying images) that work with the default ASP.NET MVC 2 templates? I'm a stereotypical developer who "doesn't do pretty" so I'd like to find a design that is good enough for me to use until I later have a designer come back and fix my design. Are there collections/libraries of various designs out there that work with the default templates? I did find this but the 2 popular ones I tried seem like they're for MVC 1, plus they in no way used the default tags with the MVC 2 templates.

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  • how to run commands (external) in gvim

    - by groovynoob
    I am getting ready to write lot of small experimental java programs as I am studying for java certification. Since I want to avoid using an IDE I'm giving gvim a try. I have a HelloWorld.java file open. How can I run javac and then java and then be able to see the output all in one window? I do not want to alt tab to a dos prompt window. compile/run the program there and then come back to my editor.

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  • Serialize WPF component using XamlWriter without default constructor

    - by mizipzor
    Ive found out that you can serialize a wpf component, in my example a FixedDocument, using the XamlWriter and a MemoryStream: FixedDocument doc = GetDocument(); MemoryStream stream = new MemoryStream(); XamlWriter.Save(doc, stream); And then to get it back: stream.Seek(0, SeekOrigin.Begin); FixedDocument result = (FixedDocument)XamlReader.Load(stream); return result; However, now I need to be able to serialize a DocumentPage as well. Which lacks a default constructor which makes the XamlReader.Load call throw an exception. Is there a way to serialize a wpf component without a default constructor?

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  • Passing paramenters on the stack

    - by oxinabox.ucc.asn.au
    When you pass parameters to a function on the cpu stack, You put the parameters on then JSR puts the return address on the stack. So than means in your function you must take the top item of the stack (the return address) before you can take the others off) eg is the following the correct way to go about it: ... |Let’s do some addition with a function, MOVE.L #4, -(SP) MOVE.L #5, -(SP) JSR add |the result of the addition (4+5) is in D0 (9) ... add: MOVE.L (SP)+, A1 |store the return address |in a register MOVE.L D0, -(SP) |get 1st parameter, put in D0 MOVE.L D2, -(SP) |get 2nd parameter, put in D0 ADD.L D2, D0 |add them, |storing the result in D0 MOVE.L A1, -(SP) |put the address back on the |Stack RTS |return

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  • Is it possible to make the AntiForgeryToken value in ASP.NET MVC change after each verification?

    - by jmcd
    We've just had some Penetration Testing carried out on an application we've built using ASP.NET MVC, and one of the recommendations that came back was that the value of the AntiForgeryToken in the Form could be resubmitted multiple times and did not expire after a single use. According to the OWASP recommendations around the Synchronizer Token Pattern: "In general, developers need only generate this token once for the current session." Which is how I think the ASP.NET MVC AntiForgeryToken works. In case we have to fight the battle, is it possible to cause the AntiForgeryToken to regenerate a new value after each validation?

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  • Do GLSL geometry shaders work on the GMA X3100 under OSX

    - by GameFreak
    I am trying to use a trivial geometry shader but when run in Shader Builder on a laptop with a GMA X3100 it falls back and uses the software render. According this document the GMA X3100 does support EXT_geometry_shader4. The input is POINTS and the output is LINE_STRIP. What would be required to get it to run on the GPU (if possible) uniform vec2 offset; void main() { gl_Position = gl_PositionIn[0]; EmitVertex(); gl_Position = gl_PositionIn[0] + vec4(offset.x,offset.y,0,0); EmitVertex(); EndPrimitive(); }

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  • Android Programmatically created Button Persistance

    - by WtLgi
    So in an app I'm messing around with I programmatically create some buttons. Then I setContentView(); to a different page. Then if I come back to the original page (on which I placed the programmatically created buttons), they no longer exist. I guess this makes sense as I am calling setContentView(R.layout.main); again which is just the original xml file with no data pointing to the buttons. So is there a way to have the buttons persist over such screen transitions? Thanks.

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  • functional-style datatypes in Python

    - by Danny Roberts
    For anyone who's spent some time with sml, ocaml, haskell, etc. when you go back to using C, Python, Java, etc. you start to notice things you never knew were missing. I'm doing some stuff in Python and I realized what I really want is a functional-style datatype like (for example) datatype phoneme = Vowel of string | Consonant of voice * place * manner datatype voice = Voiced | Voiceless datatype place = Labial | Dental | Retroflex | Palatal | Velar | Glottal datatype manner = Stop | Affricate | Fricative | Nasal | Lateral type syllable = phoneme list Does anyone have a particular way that they like to simulate this in Python?

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  • Removing NSOperation from queue when view changes.

    - by Nithin
    I am creating an application which involves so many web-service calls. I am using NSOperation to execute the web-service calls. There are several views in the application and I'm calling the web-service each time the view loads. Since it is navigation, if user decides to go back to the previous view even before the operation gets completed, another operation is getting into the queue and will be waiting for the previous operation to be completed. Is there any way to stop the previous operation from being executed when its view changes? pls help

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  • asp.net 2.0 session timeout

    - by d3020
    I apologize in advance for this likely being asked before. I have an asp.net 2.0 web application and am trying to set the session timeout. My first attempt was to add this to the web.config. < sessionState mode="InProc" timeout="300" Users would tell me though that after about 20 minutes of being idle and then trying to do something again on the site they'd be redirected back to the login page. So now I'm trying timeout="60" in my < forms tag in the web.config. I also tried Session.Timeout=60 in my global.asax. Should these work? Do I need something else? Thank you for your time and help.

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  • InvalidCastException when creating an instance using assembly.CreateInstance

    - by Yossi Dahan
    I'm looking for an explanation for the following - I have an assembly I'm loading using Assembly assembly = Assembly.LoadFrom(filename); I then loop on all the types in the assembly, and wish to try and find out if a type implements a particular interface and if so I want an instance of that type, I've tried several things which did not work, but when I fell back to the most basic (and probably inefficient) way, I realised there's something more fundamental I don't understand - foreach (Type t in assembly.GetTypes()) { foreach (Type i in t.GetInterfaces()) { if (i.FullName == pluginInterfaceType.FullName) { object o = assembly.CreateInstance(t.ToString()); IInterface plugin = (IInterface)o; That last line causes an InvalidCastException, despite the fact that the type created definitely implements that interface. Further more - if I use Activator.CreateInstance instead of Assembly.CreateInstance (which I don't want to do), casting to the interface works just fine.

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  • Avoid XmlDocument validating namespaces in C#

    - by Abbey Kingston
    Hello, I'm trying to find a way of indenting a HTML file, I've been using XMLDocument and just using a XmlTextWriter. However I am unable to format it correctly for HTML documents because it checks the doctype and tries to download it. Is there a "dumb" indenting mechanism that doesnt validate or check the document and does a best effort indentation? The files are 4-10Mb in size and they are autogenerated, we have to handle it internal - its fine, the user can wait, I just want to avoid forking to a new process etc. Essentially, right now I use a MemoryStream, XmlTextWriter and XmlDocument, once indented I read it back from the MemoryStream and return it as a string. Failures happen for XHTML documents and some HTML 4 documents because its trying to grab the dtds. I tried setting XmlResolver as null but to no avail :(

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  • How to hook Pivotal Tracker to Redmine?

    - by cloneofsnake
    Our company is currently using Redmine, it's great for general tasks / troubleshooting (operation) but for development, I would like to adopt a more agile tool... and I found it in pivotaltracker. I googled but couldn't find any info., so that gave me a good excuse to try StackOverflow. Has anyone done it? I'm thinking of using PivotalTracker as the main tool, and all activities will be posted back to redmine for archiving and reporting. (Redmine isn't particularly strong at that either, but it does have a budget plugin and I can query the database directly for my custom reports.) Thanks.

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  • Problem with the scrollbar of a UIWebView

    - by Paulo Ferreira
    Hi there! Im using a UIWebView to access a website, when i rotate the phone (landscape) the UIWebView is properly resized and the scrollbar are on the right place (on the right edge...) but when i acess any of input fields to fill the information required and exit it the UIWebView scrollbar jumps to the middle of screen (looks like it get back to 320, the width of the screen on portrait). Some useful info, this program was created using IB, have lots of outlets, im thinking about in do (redo) everything programmatically cause i was not the author of the first version... If anyone have seen this before plz let me know.. Thanks in advance!

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  • How to download a file from a server using Java Socket?

    - by Ada
    Hi, I have an assignment about uploading and downloading a file to a server. I managed to do the uploading part using Java Sockets however I am having a hard time doing the downloading part. I should use Range: for downloading parellel. In my request, I should have the Range: header. But I don't understand how I will receive the file with that HTTP GET request. All the examples I have seen was about uploading a file. I already did it. I can upload .exe, image, .pdf, anything and when I download them back (by my browser), there are no errors. Can you help me with the downloading part? Can you give me an example beacuse I really didn't get it.

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  • Django - Form validation error

    - by Igor G.
    Hello, I have a model like this: class Entity(models.Model): entity_name = models.CharField(max_length=100) entity_id = models.CharField(max_length=30, primary_key=True) entity_parent = models.CharField(max_length=100, null=True) photo_id = models.CharField(max_length=100, null=True) username = models.CharField(max_length=100, null=True) date_matched_on = models.CharField(max_length=100, null=True) status = models.CharField(max_length=30, default="Checked In") def __unicode__(self): return self.entity_name class Meta: app_label = 'match' ordering = ('entity_name','date_matched_on') verbose_name_plural='Entities' I also have a view like this: def photo_match(request): ''' performs an update in the db when a user chooses a photo ''' form = EntityForm(request.POST) form.save() And my EntityForm looks like this: class EntityForm(ModelForm): class Meta: model = Entity My template's form returns a POST back to the view with the following values: {u'username': [u'admin'], u'entity_parent': [u'PERSON'], u'entity_id': [u'152097'], u'photo_id': [u'2200734'], u'entity_name': [u'A.J. McLean'], u'status': [u'Checked Out'], u'date_matched_on': [u'5/20/2010 10:57 AM']} And form.save() throws this error: Exception in photo_match: The Entity could not be changed because the data didn't validate. I have been trying to figure out why this is happening, but cannot pinpoint the exact problem. I can change my Entities in the admin interface just fine. If anybody has a clue about this I would greatly appreciate it! Thanks, Igor

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  • Guest Post: Using IronRuby and .NET to produce the &lsquo;Hello World of WPF&rsquo;

    - by Eric Nelson
    [You might want to also read other GuestPosts on my blog – or contribute one?] On the 26th and 27th of March (2010) myself and Edd Morgan of Microsoft will be popping along to the Scottish Ruby Conference. I dabble with Ruby and I am a huge fan whilst Edd is a “proper Ruby developer”. Hence I asked Edd if he was interested in creating a guest post or two for my blog on IronRuby. This is the second of those posts. If you should stumble across this post and happen to be attending the Scottish Ruby Conference, then please do keep a look out for myself and Edd. We would both love to chat about all things Ruby and IronRuby. And… we should have (if Amazon is kind) a few books on IronRuby with us at the conference which will need to find a good home. This is me and Edd and … the book: Order on Amazon: http://bit.ly/ironrubyunleashed Using IronRuby and .NET to produce the ‘Hello World of WPF’ In my previous post I introduced, to a minor extent, IronRuby. I expanded a little on the basics of by getting a Rails app up-and-running on this .NET implementation of the Ruby language — but there wasn't much to it! So now I would like to go from simply running a pre-existing project under IronRuby to developing a whole new application demonstrating the seamless interoperability between IronRuby and .NET. In particular, we'll be using WPF (Windows Presentation Foundation) — the component of the .NET Framework stack used to create rich media and graphical interfaces. Foundations of WPF To reiterate, WPF is the engine in the .NET Framework responsible for rendering rich user interfaces and other media. It's not the only collection of libraries in the framework with the power to do this — Windows Forms does the trick, too — but it is the most powerful and flexible. Put simply, WPF really excels when you need to employ eye candy. It's all about creating impact. Whether you're presenting a document, video, a data entry form, some kind of data visualisation (which I am most hopeful for, especially in terms of IronRuby - more on that later) or chaining all of the above with some flashy animations, you're likely to find that WPF gives you the most power when developing any of these for a Windows target. Let's demonstrate this with an example. I give you what I like to consider the 'hello, world' of WPF applications: the analogue clock. Today, over my lunch break, I created a WPF-based analogue clock using IronRuby... Any normal person would have just looked at their watch. - Twitter The Sample Application: Click here to see this sample in full on GitHub. Using Windows Presentation Foundation from IronRuby to create a Clock class Invoking the Clock class   Gives you The above is by no means perfect (it was a lunch break), but I think it does the job of illustrating IronRuby's interoperability with WPF using a familiar data visualisation. I'm sure you'll want to dissect the code yourself, but allow me to step through the important bits. (By the way, feel free to run this through ir first to see what actually happens). Now we're using IronRuby - unlike my previous post where we took pure Ruby code and ran it through ir, the IronRuby interpreter, to demonstrate compatibility. The main thing of note is the very distinct parallels between .NET namespaces and Ruby modules, .NET classes and Ruby classes. I guess there's not much to say about it other than at this point, you may as well be working with a purely Ruby graphics-drawing library. You're instantiating .NET objects, but you're doing it with the standard Ruby .new method you know from Ruby as Object#new — although, the root object of all your IronRuby objects isn't actually Object, it's System.Object. You're calling methods on these objects (and classes, for example in the call to System.Windows.Controls.Canvas.SetZIndex()) using the underscored, lowercase convention established for the Ruby language. The integration is so seamless. The fact that you're using a dynamic language on top of .NET's CLR is completely abstracted from you, allowing you to just build your software. A Brief Note on Events Events are a big part of developing client applications in .NET as well as under every other environment I can think of. In case you aren't aware, event-driven programming is essentially the practice of telling your code to call a particular method, or other chunk of code (a delegate) when something happens at an unpredictable time. You can never predict when a user is going to click a button, move their mouse or perform any other kind of input, so the advent of the GUI is what necessitated event-driven programming. This is where one of my favourite aspects of the Ruby language, blocks, can really help us. In traditional C#, for instance, you may subscribe to an event (assign a block of code to execute when an event occurs) in one of two ways: by passing a reference to a named method, or by providing an anonymous code block. You'd be right for seeing the parallel here with Ruby's concept of blocks, Procs and lambdas. As demonstrated at the very end of this rather basic script, we are using .NET's System.Timers.Timer to (attempt to) update the clock every second (I know it's probably not the best way of doing this, but for example's sake). Note: Diverting a little from what I said above, the ticking of a clock is very predictable, yet we still use the event our Timer throws to do this updating as one of many ways to perform that task outside of the main thread. You'll see that all that's needed to assign a block of code to be triggered on an event is to provide that block to the method of the name of the event as it is known to the CLR. This drawback to this is that it only allows the delegation of one code block to each event. You may use the add method to subscribe multiple handlers to that event - pushing that to the end of a queue. Like so: def tick puts "tick tock" end timer.elapsed.add method(:tick) timer.elapsed.add proc { puts "tick tock" } tick_handler = lambda { puts "tick tock" } timer.elapsed.add(tick_handler)   The ability to just provide a block of code as an event handler helps IronRuby towards that very important term I keep throwing around; low ceremony. Anonymous methods are, of course, available in other more conventional .NET languages such as C# and VB but, as usual, feel ever so much more elegant and natural in IronRuby. Note: Whether it's a named method or an anonymous chunk o' code, the block you delegate to the handling of an event can take arguments - commonly, a sender object and some args. Another Brief Note on Verbosity Personally, I don't mind verbose chaining of references in my code as long as it doesn't interfere with performance - as evidenced in the example above. While I love clean code, there's a certain feeling of safety that comes with the terse explicitness of long-winded addressing and the describing of objects as opposed to ambiguity (not unlike this sentence). However, when working with IronRuby, even I grow tired of typing System::Whatever::Something. Some people enjoy simply assuming namespaces and forgetting about them, regardless of the language they're using. Don't worry, IronRuby has you covered. It is completely possible to, with a call to include, bring the contents of a .NET-converted module into context of your IronRuby code - just as you would if you wanted to bring in an 'organic' Ruby module. To refactor the style of the above example, I could place the following at the top of my Clock class: class Clock include System::Windows::Shape include System::Windows::Media include System::Windows::Threading # and so on...   And by doing so, reduce calls to System::Windows::Shapes::Ellipse.new to simply Ellipse.new or references to System::Windows::Threading::DispatcherPriority.Render to a friendlier DispatcherPriority.Render. Conclusion I hope by now you can understand better how IronRuby interoperates with .NET and how you can harness the power of the .NET framework with the dynamic nature and elegant idioms of the Ruby language. The manner and parlance of Ruby that makes it a joy to work with sets of data is, of course, present in IronRuby — couple that with WPF's capability to produce great graphics quickly and easily, and I hope you can visualise the possibilities of data visualisation using these two things. Using IronRuby and WPF together to create visual representations of data and infographics is very exciting to me. Although today, with this project, we're only presenting one simple piece of information - the time - the potential is much grander. My day-to-day job is centred around software development and UI design, specifically in the realm of healthcare, and if you were to pay a visit to our office you would behold, directly above my desk, a large plasma TV with a constantly rotating, animated slideshow of charts and infographics to help members of our team do their jobs. It's an app powered by WPF which never fails to spark some conversation with visitors whose gaze has been hooked. If only it was written in IronRuby, the pleasantly low ceremony and reduced pre-processing time for my brain would have helped greatly. Edd Morgan blog Related Links: Getting PhP and Ruby working on Windows Azure and SQL Azure

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  • Ruby on Rails redirect_to not functioning in IF statement?

    - by Hard-Boiled Wonderland
    Hi, I am redirecting a POST request to ensure the URL is correct along with other things. The redirect worked fine before I added in the if statements for town below: if !params[:address].blank? town = Town.find(:all, :conditions => ["name = ?", params[:address]]) @towns = town if !town.blank? redirect_to '/town/' + params[:address] else @town_invalid = 'test' end end end I am sure it is something simple and that I simply cannot see it. Also if you see any glaring errors or code mishaps let me know as I am just starting out. EDIT: I should mention this is what I get back from Safari when a real town is entered: Safari can’t open the page.Safari can’t open the page “http://localhost:3000/” because the server unexpectedly dropped the connection. This sometimes occurs when the server is busy. Wait for a few minutes, and then try again. Thanks!

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  • Sql Server 2008 Install

    - by Steve
    I already have Visual Studio 2008 installed. When installing developer Sql Server 2008, do I need to check the Business Intelligence Development Studio option? I'm guessing not. I assume if I already have VS 2008, the install will just add the relevant Sql Server related project types into VS 2008. EDIT: I marked the question answered before I did the install - I've installed Sql Server before and I thought this was what happened, but on doing this install, leaving the BI studio option unchecked does NOT install the SQL Server projects in Visual Studio. I had to go back and install it, so the answer is... Check it! I was overthinking the install - it's smart enough not to install VS twice.

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