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• ANTS CLR and Memory Profiler In Depth Review (Part 2 of 2 &ndash; Memory Profiler)

  - by ToStringTheory

  One of the things that people might not know about me, is my obsession to make my code as efficient as possible. Many people might not realize how much of a task or undertaking that this might be, but it is surely a task as monumental as climbing Mount Everest, except this time it is a challenge for the mind… In trying to make code efficient, there are many different factors that play a part – size of project or solution, tiers, language used, experience and training of the programmer, technologies used, maintainability of the code – the list can go on for quite some time. I spend quite a bit of time when developing trying to determine what is the best way to implement a feature to accomplish the efficiency that I look to achieve. One program that I have recently come to learn about – Red Gate ANTS Performance (CLR) and Memory profiler gives me tools to accomplish that job more efficiently as well. In this review, I am going to cover some of the features of the ANTS memory profiler set by compiling some hideous example code to test against. Notice As a member of the Geeks With Blogs Influencers program, one of the perks is the ability to review products, in exchange for a free license to the program. I have not let this affect my opinions of the product in any way, and Red Gate nor Geeks With Blogs has tried to influence my opinion regarding this product in any way. Introduction – Part 2 In my last post, I reviewed the feature packed Red Gate ANTS Performance Profiler.  Separate from the Red Gate Performance Profiler is the Red Gate ANTS Memory Profiler – a simple, easy to use utility for checking how your application is handling memory management…  A tool that I wish I had had many times in the past.  This post will be focusing on the ANTS Memory Profiler and its tool set. The memory profiler has a large assortment of features just like the Performance Profiler, with the new session looking nearly exactly alike: ANTS Memory Profiler Memory profiling is not something that I have to do very often…  In the past, the few cases I’ve had to find a memory leak in an application I have usually just had to trace the code of the operations being performed to look for oddities…  Sadly, I have come across more undisposed/non-using’ed IDisposable objects, usually from ADO.Net than I would like to ever see.  Support is not fun, however using ANTS Memory Profiler makes this task easier.  For this round of testing, I am going to use the same code from my previous example, using the WPF application. This time, I will choose the ‘Profile Memory’ option from the ANTS menu in Visual Studio, which launches the solution in its currently configured state/start-up project, and then launches the ANTS Memory Profiler to help.  It prepopulates all of the fields with the current project information, and all I have to do is select the ‘Start Profiling’ option. When the window comes up, it is actually quite barren, just giving ideas on how to work the profiler.  You start by getting to the point in your application that you want to profile, and then taking a ‘Memory Snapshot’.  This performs a full garbage collection, and snapshots the managed heap.  Using the same WPF app as before, I will go ahead and take a snapshot now. As you can see, ANTS is already giving me lots of information regarding the snapshot, however this is just a snapshot.  The whole point of the profiler is to perform an action, usually one where a memory problem is being noticed, and then take another snapshot and perform a diff between them to see what has changed.  I am going to go ahead and generate 5000 primes, and then take another snapshot: As you can see, ANTS is already giving me a lot of new information about this snapshot compared to the last.  Information such as difference in memory usage, fragmentation, class usage, etc…  If you take more snapshots, you can use the dropdown at the top to set your actual comparison snapshots. If you beneath the timeline, you will see a breadcrumb trail showing how best to approach profiling memory using ANTS.  When you first do the comparison, you start on the Summary screen.  You can either use the charts at the bottom, or switch to the class list screen to get to the next step.  Here is the class list screen: As you can see, it lists information about all of the instances between the snapshots, as well as at the bottom giving you a way to filter by telling ANTS what your problem is.  I am going to go ahead and select the Int16[] to look at the Instance Categorizer Using the instance categorizer, you can travel backwards to see where all of the instances are coming from.  It may be hard to see in this image, but hopefully the lightbox (click on it) will help: I can see that all of these instances are rooted to the application through the UI TextBlock control.  This image will probably be even harder to see, however using the ‘Instance Retention Graph’, you can trace an objects memory inheritance up the chain to see its roots as well.  This is a simple example, as this is simply a known element.  Usually you would be profiling an actual problem, and comparing those differences.  I know in the past, I have spotted a problem where a new context was created per page load, and it was rooted into the application through an event.  As the application began to grow, performance and reliability problems started to emerge.  A tool like this would have been a great way to identify the problem quickly. Overview Overall, I think that the Red Gate ANTS Memory Profiler is a great utility for debugging those pesky leaks.  3 Biggest Pros: Easy to use interface with lots of options for configuring profiling session Intuitive and helpful interface for drilling down from summary, to instance, to root graphs ANTS provides an API for controlling the profiler. Not many options, but still helpful. 2 Biggest Cons: Inability to automatically snapshot the memory by interval Lack of complete integration with Visual Studio via an extension panel Ratings Ease of Use (9/10) – I really do believe that they have brought simplicity to the once difficult task of memory profiling.  I especially liked how it stepped you further into the drilldown by directing you towards the best options. Effectiveness (10/10) – I believe that the profiler does EXACTLY what it purports to do.  Features (7/10) – A really great set of features all around in the application, however, I would like to see some ability for automatically triggering snapshots based on intervals or framework level items such as events. Customer Service (10/10) – My entire experience with Red Gate personnel has been nothing but good.  their people are friendly, helpful, and happy! UI / UX (9/10) – The interface is very easy to get around, and all of the options are easy to find.  With a little bit of poking around, you’ll be optimizing Hello World in no time flat! Overall (9/10) – Overall, I am happy with the Memory Profiler and its features, as well as with the service I received when working with the Red Gate personnel.  Thank you for reading up to here, or skipping ahead – I told you it would be shorter!  Please, if you do try the product, drop me a message and let me know what you think!  I would love to hear any opinions you may have on the product. Code Feel free to download the code I used above – download via DropBox

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• How to begin? Windows 8 Development

  - by Dennis Vroegop

  Ok. I convinced you in my last post to do some Win8 development. You want a piece of that cake, or whatever your reasons may be. Good! Welcome to the club! Now let me ask you a question: what are you going to write? Ah. That’s the big one, isn’t it? What indeed? If you have been creating applications for computers before you’re in for quite a shock. The way people perceive apps on a tablet is quite different from what we know as applications. There’s a reason we call them apps instead of applications! Yes, technically they are applications but we don’t call them apps only because it sounds cool. The abbreviated form of the word applications itself is a pointer. Apps are small. Apps are focused. Apps are more lightweight. Apps do one thing but they do that one thing extremely good. In the ‘old’ days we wrote huge systems. We build ecosystems of services, screens, databases and more to create a system that provides value for the user. Think about it: what application do you use most at work? Can you in one sentence describe what it is, or what it does and yet still distinctively describe its purpose? I doubt you can. Let’s have a look at Outlouk. We all know it and we all love or hate it. But what is it? A mail program? No, there’s so much more there: calendar, contacts, RSS feeds and so on. Some call it a ‘collaboration’  application but that’s not really true as well. After all, why should a collaboration application give me my schedule for the day? I think the best way to describe Outlook is “client for Exchange”  although that isn’t accurate either. Anyway: Outlook is a great application but it’s not an ‘app’ and therefor not very suitable for WinRT. Ok. Disclaimer here: yes, you can write big applications for WinRT. Some will. But that’s not what 99.9% of the developers will do. So I am stating here that big applications are not meant for WinRT. If 0.01% of the developers think that this is nonsense then they are welcome to go ahead but for the majority here this is not what we’re talking about. So: Apps are small, lightweight and good at what they do but only at that. If you’re a Phone developer you already know that: Phone apps on any platform fit the description I have above. If you’ve ever worked in a large cooperation before you might have seen one of these before: the Mission Statement. It’s supposed to be a oneliner that sums up what the company is supposed to do. Funny enough: although this doesn’t work for large companies it does work for defining your app. A mission statement for an app describes what it does. If it doesn’t fit in the mission statement then your app is going to get to big and will fail. A statement like this should be in the following style “<your app name> is the best app to <describe single task>” Fill in the blanks, write it and go! Mmm.. not really. There are some things there we need to think about. But the statement is a very, very important one. If you cannot fit your app in that line you’re preparing to fail. Your app will become to big, its purpose will be unclear and it will be hard to use. People won’t download it and those who do will give it a bad rating therefor preventing that huge success you’ve been dreaming about. Stick to the statement! Ok, let’s give it a try: “PlanesAreCool” is the best app to do planespotting in the field. You might have seen these people along runways of airports: taking photographs of airplanes and noting down their numbers and arrival- and departure times. We are going to help them out with our great app! If you look at the statement, can you guess what it does? I bet you can. If you find out it isn’t clear enough of if it’s too broad, refine it. This is probably the most important step in the development of your app so give it enough time! So. We’ve got the statement. Print it out, stick it to the wall and look at it. What does it tell you? If you see this, what do you think the app does? Write that down. Sit down with some friends and talk about it. What do they expect from an app like this? Write that down as well. Brainstorm. Make a list of features. This is mine: Note planes Look up aircraft carriers Add pictures of that plane Look up airfields Notify friends of new spots Look up details of a type of plane Plot a graph with arrival and departure times Share new spots on social media Look up history of a particular aircraft Compare your spots with friends Write down arrival times Write down departure times Write down wind conditions Write down the runway they take Look up weather conditions for next spotting day Invite friends to join you for a day of spotting. Now, I must make it clear that I am not a planespotter nor do I know what one does. So if the above list makes no sense, I apologize. There is a lesson: write apps for stuff you know about…. First of all, let’s look at our statement and then go through the list of features. Remove everything that has nothing to do with that statement! If you end up with an empty list, try again with both steps. Note planes Look up aircraft carriers Add pictures of that plane Look up airfields Notify friends of new spots Look up details of a type of plane Plot a graph with arrival and departure times Share new spots on social media Look up history of a particular aircraft Compare your spots with friends Write down arrival times Write down departure times Write down wind conditions Write down the runway they take Look up weather conditions for next spotting day Invite friends to join you for a day of spotting. That's better. The things I removed could be pretty useful to a plane spotter and could be fun to write. But do they match the statement? I said that the app is for spotting in the field, so “look up airfields” doesn’t belong there: I know where I am so why look it up? And the same goes for inviting friends or looking up the weather conditions for tomorrow. I am at the airfield right now, looking through my binoculars at the planes. I know the weather now and I don’t care about tomorrow. If you feel the items you’ve crossed out are valuable, then why not write another app? One that says “SpotNoter” is the best app for preparing a day of spotting with my friends. That’s a different app! Remember: Win8 apps are small and very good at doing ONE thing, and one thing only! If you have made that list, it’s time to prepare the navigation of your app. The navigation is how users see your app and how they use it. We’ll do that next time!

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• VNIC - New feature of AK8 - Working with VNICs

  - by Steve Tunstall

  One of the important new features of the AK8 code is the ability to use multiple IP addresses on the same physical network port. This feature is called VNICs, or Virtual NICs. This allows us to no longer "burn" a whole port in a cluster when one cluster peer owns a network port. Traditionally, we have had to leave Net0 empty on controller 2, because it was used for managing controller 1. Vise-versa for Net1 on Controller 1. Then, if you have data going over 10GigE ports, you probably only had half of your ports running at any given time, and the partner 10GigE port on the other controller just sat there, doing nothing, unless the first controller went down. What a waste. Those days are over.  I want to thank and give a big shout-out to our good partner, OnX Enterprise Solutions, for allowing me to come into their lab and play around with their 7320 to do this demo. They let me make a big mess of their lab for the day as I played around with VNICs. If you're looking for a partner who knows Oracle well and can also piece together a solution from multiple vendors to get you what you need, OnX is a good choice. If you would like to talk to your local OnX rep, you can contact Scott Gill at [email protected] and he can point you in the right direction for your area.  Here we go: Here is what your Datalinks window looks like BEFORE you upgrade to AK8. Here's what the same screen looks like after you upgrade. See the new box? So here is my current network setup. I have my 4 physical interfaces setup each with an IP address. If I ping them, no problems.  So I can ping 180, 181, 251, and 252. However, if I try to ping 240, it does not work, as the 240 address is not being used by any of these interfaces, right?Let's change that. Here, I'm going to make a new Datalink by clicking the Datalink "Plus sign" button. I will check the VNIC box and tell it to use igb2, even though another interface is already using it. Now, I will create a new Interface, and choose "v_dl2" for it's datalink. My new network screen looks like this. A few things to take note of here. First, when I click the "igb2" device, it only highlights dl2 and int2. It does not highlight v_dl2 or v_int2.I think it should, but OK, it looks like VNICs don't highlight when you click the device. Second, note how the underscore character in v_dl2 and v_int2 do not seem to show on this screen. You can see it plainly if you go in and edit them, but from here it looks like a space instead of an underscore. Just a cosmetic bug, but something to be aware of. Now, if I click the VNIC datalink "v_dl2", on the other hand, it DOES highlight the device it belongs to, as it should. Seen here: Note that it did not, however, highlight int2 with it, even though int2 is connected to igb2. That's because we clicked v_dl2, which int2 has nothing to do with. So I'm OK with that. So let's try pinging 240 now. Of course, it works great.  So I now make another VNIC, and call it v_dl3 using igb3, and v_int3 with an address of 241. I then setup three shares, using ports 251, 240, and 241.Remember that IP 251 and 240 both are using the same physical port of igb2, and IP 241 is using port igb3. Next, I copy a folder full of stuff over to all three shares at the same time. I have analytics going so I can see the traffic. My top chart is showing the logical interfaces, and the bottom chart is showing the physical ports.Sure enough, look at the igb2 and vnic1 interfaces. They equal the traffic going over the igb2 physical port on the second chart. VNIC2, on the other hand, gets igb3 all to itself. This would work the same way with 10Gig or Infiniband ports. You can now have multiple IP addresses and even completely different subnets sharing the same physical ports. You may need to make route table entries for that. This allows us to use all of the ports you paid for with no more waste.  Very, very cool.  One small "bug" I found when doing this. It's really not a bug, it was designed to do this when VNICs were not around. But now that we have NVIC capability, they should probably change this. I've alerted the engineering team about this and they're looking into it, so perhaps it will be fixed in a later code. Here it is. Remember when we made the new VNIC datalink, I specifically said to click on the "Plus Sign" button to create it? I don't always do that. I really like to use the drag-and-drop method to create my datalinks in the network screen.HOWEVER, if you were to do that for building a VNIC, it will mess you up a little. Watch this. Here, I'm dragging igb3 over to make a new datalink. igb3 is already being used by dl3, but I'm going to make this a VNIC, so who cares, right? Well, the ZFSSA does not KNOW you are going to make it a VNIC, now does it? So... it works as designed and REMOVES the igb3 device from the current dl3 datalink in the background. See how it's now missing? At the same time, the dl3 datalink choice is missing from my list of possible VNICs for me to choose from!!!! Hey!!! I wanted to pick dl3. Why isn't it on the list??? Well, it can't be on this list because dl3 no longer has a device associated with it. Bummer for you. When you click cancel, the device is still missing from dl3. The fix is easy. Just edit dl3 by clicking the pencil button, do absolutely nothing, and click "Apply". The device will magically come back. Now, make the VNIC datalink by clicking the "Plus Sign" button. Sure enough, once you check the VNIC box, dl3 is a valid choice. No problem.  That's it for now. Have fun with VNICs.

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• SSH service will not start on fresh Cygwin 1.7.15 install

  - by Coder6841

  OS: Windows 7 x64 Cygwin: 1.7.15-1 OpenSSH: 6.0p1-1 I'm attempting to install an SSH server on Windows 7. The tutorial that I'm following to do this is here: http://www.howtogeek.com/howto/41560/how-to-get-ssh-command-line-access-to-windows-7-using-cygwin/ The issue is that upon executing the net start sshd command I get the following output:The CYGWIN sshd service is starting. The CYGWIN sshd service could not be started. The service did not report an error. More help is available by typing NET HELPMSG 3534. Here is the full output of the setup: AdminUser@ThisComputer ~ $ ssh-host-config *** Info: Generating /etc/ssh_host_key *** Info: Generating /etc/ssh_host_rsa_key *** Info: Generating /etc/ssh_host_dsa_key *** Info: Generating /etc/ssh_host_ecdsa_key *** Info: Creating default /etc/ssh_config file *** Info: Creating default /etc/sshd_config file *** Info: Privilege separation is set to yes by default since OpenSSH 3.3. *** Info: However, this requires a non-privileged account called 'sshd'. *** Info: For more info on privilege separation read /usr/share/doc/openssh/README.privsep. *** Query: Should privilege separation be used? (yes/no) yes *** Info: Note that creating a new user requires that the current account have *** Info: Administrator privileges. Should this script attempt to create a *** Query: new local account 'sshd'? (yes/no) yes *** Info: Updating /etc/sshd_config file *** Query: Do you want to install sshd as a service? *** Query: (Say "no" if it is already installed as a service) (yes/no) yes *** Query: Enter the value of CYGWIN for the daemon: [] *** Info: On Windows Server 2003, Windows Vista, and above, the *** Info: SYSTEM account cannot setuid to other users -- a capability *** Info: sshd requires. You need to have or to create a privileged *** Info: account. This script will help you do so. *** Info: You appear to be running Windows XP 64bit, Windows 2003 Server, *** Info: or later. On these systems, it's not possible to use the LocalSystem *** Info: account for services that can change the user id without an *** Info: explicit password (such as passwordless logins [e.g. public key *** Info: authentication] via sshd). *** Info: If you want to enable that functionality, it's required to create *** Info: a new account with special privileges (unless a similar account *** Info: already exists). This account is then used to run these special *** Info: servers. *** Info: Note that creating a new user requires that the current account *** Info: have Administrator privileges itself. *** Info: No privileged account could be found. *** Info: This script plans to use 'cyg_server'. *** Info: 'cyg_server' will only be used by registered services. *** Query: Do you want to use a different name? (yes/no) no *** Query: Create new privileged user account 'cyg_server'? (yes/no) yes *** Info: Please enter a password for new user cyg_server. Please be sure *** Info: that this password matches the password rules given on your system. *** Info: Entering no password will exit the configuration. *** Query: Please enter the password: *** Query: Reenter: *** Info: User 'cyg_server' has been created with password '[CENSORED]'. *** Info: If you change the password, please remember also to change the *** Info: password for the installed services which use (or will soon use) *** Info: the 'cyg_server' account. *** Info: Also keep in mind that the user 'cyg_server' needs read permissions *** Info: on all users' relevant files for the services running as 'cyg_server'. *** Info: In particular, for the sshd server all users' .ssh/authorized_keys *** Info: files must have appropriate permissions to allow public key *** Info: authentication. (Re-)running ssh-user-config for each user will set *** Info: these permissions correctly. [Similar restrictions apply, for *** Info: instance, for .rhosts files if the rshd server is running, etc]. *** Info: The sshd service has been installed under the 'cyg_server' *** Info: account. To start the service now, call `net start sshd' or *** Info: `cygrunsrv -S sshd'. Otherwise, it will start automatically *** Info: after the next reboot. *** Info: Host configuration finished. Have fun! AdminUser@ThisComputer ~ $ net start sshd The CYGWIN sshd service is starting. The CYGWIN sshd service could not be started. The service did not report an error. More help is available by typing NET HELPMSG 3534. Note that on the line *** Query: Enter the value of CYGWIN for the daemon: [] I haven't entered anything. Tutorials often say to use ntsec or ntsec tty here but those options are removed from the latest version of OpenSSH. I've tried using them anyway and the result is the same. The file /var/log/sshd.log is empty. If I try just running the command /usr/sbin/sshd I get the output /var/empty must be owned by root and not group or world-writable.. The /var/empty directory has the following permissions: drwxr-xr-x+ 1 cyg_server root 0 May 29 15:28 empty. Google searches on this error did not turn up any working fixes. One person seems to have solved it by using the command chown SYSTEM /var/empty but that did not fix it in my case.

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• Mercurial hg clone on Windows via ssh with copSSH issue

  - by Kyle Tolle

  I have a Windows Server 2008 machine (iis7) that has CopSSH set up on it. To connect to it, I have a Windows 7 machine with Mercurial 1.5.1 (and TortoiseHg) installed. I can connect to the server using PuTTY with a non-standard ssh port and a .ppk file just fine. So I know the server can be SSH'd into. Next, I wanted to use the CLI to connect via hg clone to get a private repo. I've seen elsewhere that you need to have ssh configured in your mercurial.ini file, so my mercurial.ini has a line: ssh = plink.exe -ssh -C -l username -P #### -i "C:/Program Files/PuTTY/Key Files/KyleKey.ppk" Note: username is filled in with the username I set up via copSSH. #### is filled in with the non-standard ssh port I've defined for copSSH. I try to do the command hg clone ssh://inthom.com but I get this error: remote: bash: inthom.com: command not found abort: no suitable response from remote hg! It looks like hg or plink parses the hostname such that it thinks that inthom.com is a command instead of the server to ssh to. That's really odd. Next, I tried to just use plink to connect by plink -P #### ssh://inthom.com, and I am then prompted for my username, and next password. I enter them both and then I get this error: bash: ssh://inthom.com: No such file or directory So now it looks like plink doesn't parse the hostname correctly. I fiddled around for a while trying to figure out how to do call hg clone with an empty ssh:// field and eventually figured out that this command allows me to reach the server and clone a test repo on the inthom.com server: hg clone ssh://!/Repos/test ! is the character I've found that let's me leave the hostname blank, but specify the repo folder to clone. What I really don't understand is how plink knows what server to ssh to at all. neither my mercurial.ini nor the command specify a server. None of the hg clone examples I've seen have a ! character. They all use an address, which makes sense, so you can connect to any repo via ssh that you want to clone. My only guess is that it somehow defaults to the last server I used PuTTY to SSH to, but I SSH'd into another server, and then tried to use plink to get to it, but plink still defaults to inthom.com (verified with the -v arg to plink). So I am at a loss as to how plink gets this server value at all. For "fun", I tried using TortoiseHg and can only clone a repo when I use ssh://!/Repos/test as the Source. Now, you can see that, since plink doesn't parse the hostname correctly, I had to specify the port number and username in the mercurial.ini file, instead of in the hostname like [email protected]:#### like you'd expect to. Trying to figure this out at first drove me insane, because I would get errors that the host couldn't be reached, which I knew shouldn't be the case. My question is how can I configure my setup so that ssh://[email protected]:####/Repos/test is parsed correctly as the username, hostname, port number, and repo to copy? Is it something wrong with the version of plink that I'm using, or is there some setting I may have messed up? If it is plink's fault, is there an alternative tool I can use? I'm going to try to get my friend set up to connect to this same repo, so I'd like to have a clean solution instead of this ! business. Especially when I have no idea how plink gets this default server, so I'm not sure if he'd even be able to get to inthom.com correctly. PS. I've had to use a ton of different tutorials to even get to this stage. Therefore, I haven't tried pushing any changes to the server yet. Hopefully I'll get this figured out and then I can try pushing changes to the repo.

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• Streaming a webcam from Silverlight 4 (Beta)

  - by Ken Smith

  The new webcam stuff in Silverlight 4 is darned cool. By exposing it as a brush, it allows scenarios that are way beyond anything that Flash has. At the same time, accessing the webcam locally seems like it's only half the story. Nobody buys a webcam so they can take pictures of themselves and make funny faces out of them. They buy a webcam because they want other people to see the resulting video stream, i.e., they want to stream that video out to the Internet, a lay Skype or any of the dozens of other video chat sites/applications. And so far, I haven't figured out how to do that with It turns out that it's pretty simple to get a hold of the raw (Format32bppArgb formatted) bytestream, as demonstrated here. But unless we want to transmit that raw bytestream to a server (which would chew up way too much bandwidth), we need to encode that in some fashion. And that's more complicated. MS has implemented several codecs in Silverlight, but so far as I can tell, they're all focused on decoding a video stream, not encoding it in the first place. And that's apart from the fact that I can't figure out how to get direct access to, say, the H.264 codec in the first place. There are a ton of open-source codecs (for instance, in the ffmpeg project here), but they're all written in C, and they don't look easy to port to C#. Unless translating 10000+ lines of code that look like this is your idea of fun :-) const int b_xy= h->mb2b_xy[left_xy[i]] + 3; const int b8_xy= h->mb2b8_xy[left_xy[i]] + 1; *(uint32_t*)h->mv_cache[list][cache_idx ]= *(uint32_t*)s->current_picture.motion_val[list][b_xy + h->b_stride*left_block[0+i*2]]; *(uint32_t*)h->mv_cache[list][cache_idx+8]= *(uint32_t*)s->current_picture.motion_val[list][b_xy + h->b_stride*left_block[1+i*2]]; h->ref_cache[list][cache_idx ]= s->current_picture.ref_index[list][b8_xy + h->b8_stride*(left_block[0+i*2]>>1)]; h->ref_cache[list][cache_idx+8]= s->current_picture.ref_index[list][b8_xy + h->b8_stride*(left_block[1+i*2]>>1)]; The mooncodecs folder within the Mono project (here) has several audio codecs in C# (ADPCM and Ogg Vorbis), and one video codec (Dirac), but they all seem to implement just the decode portion of their respective formats, as do the java implementations from which they were ported. I found a C# codec for Ogg Theora (csTheora, http://www.wreckedgames.com/forum/index.php?topic=1053.0), but again, it's decode only, as is the jheora codec on which it's based. Of course, it would presumably be easier to port a codec from Java than from C or C++, but the only java video codecs that I found were decode-only (such as jheora, or jirac). So I'm kinda back at square one. It looks like our options for hooking up a webcam (or microphone) through Silverlight to the Internet are: (1) Wait for Microsoft to provide some guidance on this; (2) Spend the brain cycles porting one of the C or C++ codecs over to Silverlight-compatible C#; (3) Send the raw, uncompressed bytestream up to a server (or perhaps compressed slightly with something like zlib), and then encode it server-side; or (4) Wait for someone smarter than me to figure this out and provide a solution. Does anybody else have any better guidance? Have I missed something that's just blindingly obvious to everyone else? (For instance, does Silverlight 4 somewhere have some classes I've missed that take care of this?)

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• overriding ctype<wchar_t>

  - by Potatoswatter

  I'm writing a lambda calculus interpreter for fun and practice. I got iostreams to properly tokenize identifiers by adding a ctype facet which defines punctuation as whitespace: struct token_ctype : ctype<char> { mask t[ table_size ]; token_ctype() : ctype<char>( t ) { for ( size_t tx = 0; tx < table_size; ++ tx ) { t[tx] = isalnum( tx )? alnum : space; } } }; (classic_table() would probably be cleaner but that doesn't work on OS X!) And then swap the facet in when I hit an identifier: locale token_loc( in.getloc(), new token_ctype ); … locale const &oldloc = in.imbue( token_loc ); in.unget() >> token; in.imbue( oldloc ); There seems to be surprisingly little lambda calculus code on the Web. Most of what I've found so far is full of unicode ? characters. So I thought to try adding Unicode support. But ctype<wchar_t> works completely differently from ctype<char>. There is no master table; there are four methods do_is x2, do_scan_is, and do_scan_not. So I did this: struct token_ctype : ctype< wchar_t > { typedef ctype<wchar_t> base; bool do_is( mask m, char_type c ) const { return base::do_is(m,c) || (m&space) && ( base::do_is(punct,c) || c == L'?' ); } const char_type* do_is (const char_type* lo, const char_type* hi, mask* vec) const { base::do_is(lo,hi,vec); for ( mask *vp = vec; lo != hi; ++ vp, ++ lo ) { if ( *vp & punct || *lo == L'?' ) *vp |= space; } return hi; } const char_type *do_scan_is (mask m, const char_type* lo, const char_type* hi) const { if ( m & space ) m |= punct; hi = do_scan_is(m,lo,hi); if ( m & space ) hi = find( lo, hi, L'?' ); return hi; } const char_type *do_scan_not (mask m, const char_type* lo, const char_type* hi) const { if ( m & space ) { m |= punct; while ( * ( lo = base::do_scan_not(m,lo,hi) ) == L'?' && lo != hi ) ++ lo; return lo; } return base::do_scan_not(m,lo,hi); } }; (Apologies for the flat formatting; the preview converted the tabs differently.) The code is WAY less elegant. I does better express the notion that only punctuation is additional whitespace, but that would've been fine in the original had I had classic_table. Is there a simpler way to do this? Do I really need all those overloads? (Testing showed do_scan_not is extraneous here, but I'm thinking more broadly.) Am I abusing facets in the first place? Is the above even correct? Would it be better style to implement less logic?

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• Getting values from Dynamic elements.

  - by nCdy

  I'm adding some dynamic elements to my WebApp this way : (Language used is Nemerele (It has a simple C#-like syntax)) unless (GridView1.Rows.Count==0) { foreach(index with row = GridView1.Rows[index] in [0..GridView1.Rows.Count-1]) { row.Cells[0].Controls.Add ({ def TB = TextBox(); TB.EnableViewState = false; unless(row.Cells[0].Text == "&nbsp;") { TB.Text = row.Cells[0].Text; row.Cells[0].Text = ""; } TB.ID=TB.ClientID; TB.Width = 60; TB }); row.Cells[0].Controls.Add ({ def B = Button(); B.EnableViewState = false; B.Width = 80; B.Text = "?????????"; B.UseSubmitBehavior=false; // Makes no sense //B.OnClientClick="select(5);"; // HERE I CAN KNOW ABOUT TB.ID //B.Click+=EventHandler(fun(_,_) : void { }); // POST BACK KILL THAT ALL B }); } } This textboxes must make first field of GridView editable so ... but now I need to save a values. I can't do it on server side because any postback will Destroy all dynamic elements so I must do it without Post Back. So I try ... <script type="text/javascript" src="Scripts/jquery-1.4.1.min.js"></script> <script type="text/javascript"> function CallPageMethod(methodName, onSuccess, onFail) { var args = ''; var l = arguments.length; if (l > 3) { for (var i = 3; i < l - 1; i += 2) { if (args.length != 0) args += ','; args += '"' + arguments[i] + '":"' + arguments[i + 1] + '"'; } } var loc = window.location.href; loc = (loc.substr(loc.length - 1, 1) == "/") ? loc + "Report.aspx" : loc; $.ajax({ type: "POST", url: loc + "/" + methodName, data: "{" + args + "}", contentType: "application/json; charset=utf-8", dataType: "json", success: onSuccess, fail: onFail }); } function select(index) { var id = $("#id" + index).html(); CallPageMethod("SelectBook", success, fail, "id",id); } function success(response) { alert(response.d); } function fail(response) { alert("&#1054;&#1096;&#1080;&#1073;&#1082;&#1072;."); } </script> So... here is a trouble string : var id = $("#id" + index).html(); I know what is ID here : TB.ID=TB.ClientID; (when I add it) but I have no idea how to send it on Web Form. If I can add something like this div : <div id="Result" onclick="select(<%= " TB.ID " %>);"> Click here. </div> from the code it will be really goal, but I can't add this element as from CodeBehind as a dynamic element. So how can I transfer TB.ID or TB.ClientID to some static div Or how can I add some clickable dynamic element without PostBack to not destroy all my dynamic elements. Thank you.

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• Parallax backgrounds in OpenGL ES on the iPhone

  - by Scott

  I've got basically a 2d game on the iPhone and I'm trying to set up multiple backgrounds that scroll at different speeds (known as parallax backgrounds). So my thought was to just stick the backgrounds BEHIND the foreground using different z-coordinate planes, and just make them bigger than the foreground (in size) to accommodate, so that the whole thing can be scrolled (just at a different speed). And (as far as I know) I basically implemented that. The only problem is that it seems to entirely ignore whatever z-value I give it, or rather it just zeroes all of them. I see the background (I've only tested ONE background so far, to keep it simple...so for now I just have a foreground and I want one background scrolling at a different speed), but it scrolls 1:1 with my foreground, so it obviously doesn't look right, and most of it is cut off (cause it's bigger). And I've tried various z-values for the background and various near/far clipping planes...it's always the same. I'm probably just doing one simple thing wrong, but I can't figure it out. I'm wondering if it has to do with me using only 2 coordinates in glVertexPointer for the foreground? (Of course for the background I AM passing in 3) I'll post some code: This is some initial setup: glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -10.0f, 10.0f); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glEnableClientState(GL_VERTEX_ARRAY); //glEnableClientState(GL_COLOR_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); //transparency glEnable (GL_BLEND); glBlendFunc (GL_ONE, GL_ONE_MINUS_SRC_ALPHA); A little bit about my foreground's float array....it's interleaved. For my foreground it goes vertex x, vertex y, texture x, texture y, repeat. This all works just fine. This is my FOREGROUND rendering: glVertexPointer(2, GL_FLOAT, 4*sizeof(GLfloat), texes); <br> glTexCoordPointer(2, GL_FLOAT, 4*sizeof(GLfloat), (GLvoid*)texes + 2*sizeof(GLfloat)); <br> glDrawArrays(GL_TRIANGLES, 0, indexCount / 4); BACKGROUND rendering: Same drill here except this time it goes vertex x, vertex y, vertex z, texture x, texture y, repeat. Note the z value this time. I did make sure the data in this array was correct while debugging (getting the right z values). And again, it shows up...it's just not going far back in the distance like it should. glVertexPointer(3, GL_FLOAT, 5*sizeof(GLfloat), b1Texes); glTexCoordPointer(2, GL_FLOAT, 5*sizeof(GLfloat), (GLvoid*)b1Texes + 3*sizeof(GLfloat)); glDrawArrays(GL_TRIANGLES, 0, b1IndexCount / 5); And to move my camera, I just do a simple glTranslatef(x, y, 0.0f); I'm not understanding what I'm doing wrong cause this seems like the most basic 3D function imaginable...things further away are smaller and don't move as fast when the camera moves. Not the case for me. Seems like it should be pretty basic and not even really be affected by my projection and all that (though I've even tried doing glFrustum just for fun, no success). Please help, I feel like it's just one dumb thing. I will post more code if necessary.

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• What would cause ANY .NET application to crash immediately... except a project I create and Debug in

  - by blak3r

  My software recently got deployed to a customer who said that the application was crashing immediately after it started. After some initial debugging, the customer provided me remote access to one of the computers which was unable to run the application. I found that the crash wasn't specific to my application. Any application which depended on the .NET framework crashed immediately. Conveniently, Visual Studio 2008 was installed so I created a quick hello world application on it and clicked Debug. The application worked fine. But, then when I tried to execute the generated binaries in the /bin/Debug/HelloWorld.exe directory outside of visual studio it crashed. List of things i've tried (UPDATED): I checked that "Everyone" has Read&Execute permissions for c:\Windows. To test that the problem was with the .NET Framework (and not my application), I attempted to download Paint .NET on to the computers. The setup frontend crashed in the same manner. Performed a repair of the .NET framework as outlined in http://support.microsoft.com/kb/908077 (Boy was this fun and time consuming). No luck. Installed .NET 3.5 SP1 (before it just had .NET 3.5) Note: my application targets 2.0 so I did this more as a long shot... but i learned in the process that .NET 3.5 SP1 also updates the underlying frameworks. Ran Aaron Stebner's .NET Setup Verification Tool. This tool indicated that .NET was successfully installed. (I forget if i checked all the versions but at least 2.0 worked). Tested some mini hello world applications which were targeted for .NET 2.0 and .NET 3.5 and both crashed in the same way. Tried launching .NET apps via windbg cmd line. Doing this did allow me invoke my simple hello world applications. So, simple .NET hello world works when invoked by windbg or by launching via debug in visual studio... but doesn't if i try to execute it standalone. I created a dump file using WinDbg. It wasn't all that revealing to me. FAULTING_IP: mscorwks!PEImage::GetEntryPointToken+21 79f4ff9d f6401010 test byte ptr [eax+10h],10h EXCEPTION_RECORD: 0012f710 -- (.exr 0x12f710) ExceptionAddress: 79f4ff9d (mscorwks!PEImage::GetEntryPointToken+0x00000021) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 00000010 Attempt to read from address 00000010 FAULTING_THREAD: 00000b44 PROCESS_NAME: MyProcess.exe ERROR_CODE: (NTSTATUS) 0x80000003 - {EXCEPTION} Breakpoint A breakpoint has been reached. EXCEPTION_CODE: (HRESULT) 0x80000003 (2147483651) - One or more arguments are invalid DETOURED_IMAGE: 1 NTGLOBALFLAG: 0 APPLICATION_VERIFIER_FLAGS: 0 MANAGED_STACK: !dumpstack -EE OS Thread Id: 0xb44 (0) Current frame: ChildEBP RetAddr Caller,Callee EXCEPTION_OBJECT: !pe cb10b4 Exception object: 00cb10b4 Exception type: System.ExecutionEngineException Message: <none> InnerException: <none> StackTrace (generated): <none> StackTraceString: <none> HResult: 80131506 MANAGED_OBJECT_NAME: System.ExecutionEngineException CONTEXT: 0012f72c -- (.cxr 0x12f72c) eax=00000000 ebx=00000000 ecx=00000000 edx=0000000e esi=001a1490 edi=00000001 eip=79f4ff9d esp=0012f9f8 ebp=0012fa1c iopl=0 nv up ei pl zr na pe nc cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00010246 mscorwks!PEImage::GetEntryPointToken+0x21: 79f4ff9d f6401010 test byte ptr [eax+10h],10h ds:0023:00000010=?? Resetting default scope READ_ADDRESS: 00000010 FOLLOWUP_IP: mscorwks!PEImage::GetEntryPointToken+21 79f4ff9d f6401010 test byte ptr [eax+10h],10h BUGCHECK_STR: APPLICATION_FAULT_NULL_CLASS_PTR_DEREFERENCE_SHUTDOWN PRIMARY_PROBLEM_CLASS: NULL_CLASS_PTR_DEREFERENCE_SHUTDOWN DEFAULT_BUCKET_ID: NULL_CLASS_PTR_DEREFERENCE_SHUTDOWN LAST_CONTROL_TRANSFER: from 79ef02b5 to 79f4ff9d STACK_TEXT: 79f4ff9d mscorwks!PEImage::GetEntryPointToken+0x21 79ef02b5 mscorwks!PEFile::GetEntryPointToken+0xa0 79eefeaf mscorwks!SystemDomain::ExecuteMainMethod+0xd4 79fb9793 mscorwks!ExecuteEXE+0x59 79fb96df mscorwks!_CorExeMain+0x15c 7900b1b3 mscoree!_CorExeMain+0x2c 7c817077 kernel32!BaseProcessStart+0x23 SYMBOL_STACK_INDEX: 0 SYMBOL_NAME: mscorwks!PEImage::GetEntryPointToken+21 FOLLOWUP_NAME: MachineOwner MODULE_NAME: mscorwks IMAGE_NAME: mscorwks.dll DEBUG_FLR_IMAGE_TIMESTAMP: 471ef729 STACK_COMMAND: .cxr 0012F72C ; kb ; dds 12f9f8 ; kb FAILURE_BUCKET_ID: NULL_CLASS_PTR_DEREFERENCE_SHUTDOWN_80000003_mscorwks.dll!PEImage::GetEntryPointToken BUCKET_ID: APPLICATION_FAULT_NULL_CLASS_PTR_DEREFERENCE_SHUTDOWN_DETOURED_mscorwks!PEImage::GetEntryPointToken+21 WATSON_STAGEONE_URL: http://watson.microsoft.com/StageOne/MyProcess_exe/2_4_4_39/4a8a192c/unknown/0_0_0_0/bbbbbbb4/80000003/00000000.htm?Retriage=1 Followup: MachineOwner Edit 1:The event log details for this error say it's a .NET Runtime version 2.0.50727.3053 - Fatal Execution Engine Error (7A097706)(80131506). Edit 2 (10-7-09): This issue is still active. Edit 3 (3-29-10): This update is to let everyone know that I never did successfully solve the problem. The customer who's machine this was on lost interest in solving it and just reimaged the machine :(. Thanks for all the contributions though.

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• Get Asynchronous HttpResponse through Silverlight (F#)

  - by jack2010

  I am a newbie with F# and SL and playing with getting asynchronous HttpResponse through Silverlight. The following is the F# code pieces, which is tested on VS2010 and Window7 and works well, but the improvement is necessary. Any advices and discussion, especially the callback part, are welcome and great thanks. module JSONExample open System open System.IO open System.Net open System.Text open System.Web open System.Security.Authentication open System.Runtime.Serialization [<DataContract>] type Result<'TResult> = { [<field: DataMember(Name="code") >] Code:string [<field: DataMember(Name="result") >] Result:'TResult array [<field: DataMember(Name="message") >] Message:string } // The elements in the list [<DataContract>] type ChemicalElement = { [<field: DataMember(Name="name") >] Name:string [<field: DataMember(Name="boiling_point") >] BoilingPoint:string [<field: DataMember(Name="atomic_mass") >] AtomicMass:string } //http://blogs.msdn.com/b/dsyme/archive/2007/10/11/introducing-f-asynchronous-workflows.aspx //http://lorgonblog.spaces.live.com/blog/cns!701679AD17B6D310!194.entry type System.Net.HttpWebRequest with member x.GetResponseAsync() = Async.FromBeginEnd(x.BeginGetResponse, x.EndGetResponse) type RequestState () = let mutable request : WebRequest = null let mutable response : WebResponse = null let mutable responseStream : Stream = null member this.Request with get() = request and set v = request <- v member this.Response with get() = response and set v = response <- v member this.ResponseStream with get() = responseStream and set v = responseStream <- v let allDone = new System.Threading.ManualResetEvent(false) let getHttpWebRequest (query:string) = let query = query.Replace("'","\"") let queryUrl = sprintf "http://api.freebase.com/api/service/mqlread?query=%s" "{\"query\":"+query+"}" let request : HttpWebRequest = downcast WebRequest.Create(queryUrl) request.Method <- "GET" request.ContentType <- "application/x-www-form-urlencoded" request let GetAsynResp (request : HttpWebRequest) (callback: AsyncCallback) = let myRequestState = new RequestState() myRequestState.Request <- request let asyncResult = request.BeginGetResponse(callback, myRequestState) () // easy way to get it to run syncrnously w/ the asynch methods let GetSynResp (request : HttpWebRequest) : HttpWebResponse = let response = request.GetResponseAsync() |> Async.RunSynchronously downcast response let RespCallback (finish: Stream -> _) (asynchronousResult : IAsyncResult) = try let myRequestState : RequestState = downcast asynchronousResult.AsyncState let myWebRequest1 : WebRequest = myRequestState.Request myRequestState.Response <- myWebRequest1.EndGetResponse(asynchronousResult) let responseStream = myRequestState.Response.GetResponseStream() myRequestState.ResponseStream <- responseStream finish responseStream myRequestState.Response.Close() () with | :? WebException as e -> printfn "WebException raised!" printfn "\n%s" e.Message printfn "\n%s" (e.Status.ToString()) () | _ as e -> printfn "Exception raised!" printfn "Source : %s" e.Source printfn "Message : %s" e.Message () let printResults (stream: Stream)= let result = try use reader = new StreamReader(stream) reader.ReadToEnd(); finally () let data = Encoding.Unicode.GetBytes(result); let stream = new MemoryStream() stream.Write(data, 0, data.Length); stream.Position <- 0L let JsonSerializer = Json.DataContractJsonSerializer(typeof<Result<ChemicalElement>>) let result = JsonSerializer.ReadObject(stream) :?> Result<ChemicalElement> if result.Code<>"/api/status/ok" then raise (InvalidOperationException(result.Message)) else result.Result |> Array.iter(fun element->printfn "%A" element) let test = // Call Query (w/ generics telling it you wand an array of ChemicalElement back, the query string is wackyJSON too –I didn’t build it don’t ask me! let request = getHttpWebRequest "[{'type':'/chemistry/chemical_element','name':null,'boiling_point':null,'atomic_mass':null}]" //let response = GetSynResp request let response = GetAsynResp request (AsyncCallback (RespCallback printResults)) () ignore(test) System.Console.ReadLine() |> ignore

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• How to Access a descendant object's internal method in C#

  - by Giovanni Galbo

  I'm trying to access a method that is marked as internal in the parent class (in its own assembly) in an object that inherits from the same parent. Let me explain what I'm trying to do... I want to create Service classes that return IEnumberable with an underlying List to non-Service classes (e.g. the UI) and optionally return an IEnumerable with an underlying IQueryable to other services. I wrote some sample code to demonstrate what I'm trying to accomplish, shown below. The example is not real life, so please remember that when commenting. All services would inherit from something like this (only relevant code shown): public class ServiceBase<T> { protected readonly ObjectContext _context; protected string _setName = String.Empty; public ServiceBase(ObjectContext context) { _context = context; } public IEnumerable<T> GetAll() { return GetAll(false); } //These are not the correct access modifiers.. I want something //that is accessible to children classes AND between descendant classes internal protected IEnumerable<T> GetAll(bool returnQueryable) { var query = _context.CreateQuery<T>(GetSetName()); if(returnQueryable) { return query; } else { return query.ToList(); } } private string GetSetName() { //Some code... return _setName; } } Inherited services would look like this: public class EmployeeService : ServiceBase<Employees> { public EmployeeService(ObjectContext context) : base(context) { } } public class DepartmentService : ServiceBase<Departments> { private readonly EmployeeService _employeeService; public DepartmentService(ObjectContext context, EmployeeService employeeService) : base(context) { _employeeService = employeeService; } public IList<Departments> DoSomethingWithEmployees(string lastName) { //won't work because method with this signature is not visible to this class var emps = _employeeService.GetAll(true); //more code... } } Because the parent class lives is reusable, it would live in a different assembly than the child services. With GetAll(bool returnQueryable) being marked internal, the children would not be able to see each other's GetAll(bool) method, just the public GetAll() method. I know that I can add a new internal GetAll method to each service (or perhaps an intermediary parent class within the same assembly) so that each child service within the assembly can see each other's method; but it seems unnecessary since the functionality is already available in the parent class. For example: internal IEnumerable<Employees> GetAll(bool returnIQueryable) { return base.GetAll(returnIQueryable); } Essentially what I want is for services to be able to access other service methods as IQueryable so that they can further refine the uncommitted results, while everyone else gets plain old lists. Any ideas? EDIT You know what, I had some fun playing a little code golf with this... but ultimately I wouldn't be able to use this scheme anyway because I pass interfaces around, not classes. So in my example GetAll(bool returnIQueryable) would not be in the interface, meaning I'd have to do casting, which goes against what I'm trying to accomplish. I'm not sure if I had a brain fart or if I was just too excited trying to get something that I thought was neat to work. Either way, thanks for the responses.

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• Need help with BOOST_FOREACH/compiler bug

  - by Jacek Lawrynowicz

  I know that boost or compiler should be last to blame, but I can't see another explanation here. I'm using msvc 2008 SP1 and boost 1.43. In the following code snippet execution never leaves third BOOST_FOREACH loop typedef Graph<unsigned, unsigned>::VertexIterator Iter; Graph<unsigned, unsigned> g; g.createVertex(0x66); // works fine Iter it = g.getVertices().first, end = g.getVertices().second; for(; it != end; ++it) ; // fine std::pair<Iter, Iter> p = g.getVertices(); BOOST_FOREACH(unsigned handle, p) ; // fine unsigned vertex_count = 0; BOOST_FOREACH(unsigned handle, g.getVertices()) vertex_count++; // oops, infinite loop vertex_count = 0; BOOST_FOREACH(unsigned handle, g.getVertices()) vertex_count++; vertex_count = 0; BOOST_FOREACH(unsigned handle, g.getVertices()) vertex_count++; // ... last block repeated 7 times Iterator code: class Iterator : public boost::iterator_facade<Iterator, unsigned const, boost::bidirectional_traversal_tag> { public: Iterator() : list(NULL), handle(INVALID_ELEMENT_HANDLE) {} explicit Iterator(const VectorElementsList &list, unsigned handle = INVALID_ELEMENT_HANDLE) : list(&list), handle(handle) {} friend std::ostream& operator<<(std::ostream &s, const Iterator &it) { s << "[list: " << it.list <<", handle: " << it.handle << "]"; return s; } private: friend class boost::iterator_core_access; void increment() { handle = list->getNext(handle); } void decrement() { handle = list->getPrev(handle); } unsigned const& dereference() const { return handle; } bool equal(Iterator const& other) const { return handle == other.handle && list == other.list; } const VectorElementsList<T> *list; unsigned handle; }; Some ASM fun: vertex_count = 0; BOOST_FOREACH(unsigned handle, g.getVertices()) // initialization 013E1369 mov edi,dword ptr [___defaultmatherr+8 (13E5034h)] // end iterator handle: 0xFFFFFFFF 013E136F mov ebp,dword ptr [esp+0ACh] // begin iterator handle: 0x0 013E1376 lea esi,[esp+0A8h] // begin iterator list pointer 013E137D mov ebx,esi 013E137F nop // forever loop begin 013E1380 cmp ebp,edi 013E1382 jne main+238h (13E1388h) 013E1384 cmp ebx,esi 013E1386 je main+244h (13E1394h) 013E1388 lea eax,[esp+18h] 013E138C push eax // here iterator is incremented in ram 013E138D call boost::iterator_facade<detail::VectorElementsList<Graph<unsigned int,unsigned int>::VertexWrapper>::Iterator,unsigned int const ,boost::bidirectional_traversal_tag,unsigned int const &,int>::operator++ (13E18E0h) 013E1392 jmp main+230h (13E1380h) vertex_count++; // forever loop end It's easy to see that iterator handle is cached in EBP and it never gets incremented despite of a call to iterator operator++() function. I've replaced Itarator implmentation with one deriving from std::iterator and the issue persisted, so this is not iterator_facade fault. This problem exists only on msvc 2008 SP1 x86 and amd64 release builds. Debug builds on msvc 2008 and debug/release builds on msvc 2010 and gcc 4.4 (linux) works fine. Furthermore the BOOST_FOREACH block must be repeaded exacly 10 times. If it's repeaded 9 times, it's all OK. I guess that due to BOOST_FOREACH use of template trickery (const auto_any), compiler assumes that iterator handle is constant and never reads its real value again. I would be very happy to hear that my code is wrong, correct it and move on with BOOST_FOREACH, which I'm very found of (as opposed to BOOST_FOREVER :). May be related to: http://stackoverflow.com/questions/1275852/why-does-boost-foreach-not-work-sometimes-with-c-strings

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• What is the coolest thing you can do in <10 lines of simple code? Help me inspire beginners!

  - by Tom Ritter

  I'm looking for the coolest thing you can do in a few lines of simple code. I'm sure you can write a Mandelbrot set in Haskell in 15 lines but it's difficult to follow. My goal is to inspire students that programming is cool. We know that programming is cool because you can create anything you imagine - it's the ultimate creative outlet. I want to inspire these beginners and get them over as many early-learning humps as I can. Now, my reasons are selfish. I'm teaching an Intro to Computing course to a group of 60 half-engineering, half business majors; all freshmen. They are the students who came from underprivileged High schools. From my past experience, the group is generally split as follows: a few rock-stars, some who try very hard and kind of get it, the few who try very hard and barely get it, and the few who don't care. I want to reach as many of these groups as effectively as I can. Here's an example of how I'd use a computer program to teach: Here's an example of what I'm looking for: a 1-line VBS script to get your computer to talk to you: CreateObject("sapi.spvoice").Speak InputBox("Enter your text","Talk it") I could use this to demonstrate order of operations. I'd show the code, let them play with it, then explain that There's a lot going on in that line, but the computer can make sense of it, because it knows the rules. Then I'd show them something like this: 4(5*5) / 10 + 9(.25 + .75) And you can see that first I need to do is (5*5). Then I can multiply for 4. And now I've created the Object. Dividing by 10 is the same as calling Speak - I can't Speak before I have an object, and I can't divide before I have 100. Then on the other side I first create an InputBox with some instructions for how to display it. When I hit enter on the input box it evaluates or "returns" whatever I entered. (Hint: 'oooooo' makes a funny sound) So when I say Speak, the right side is what to Speak. And I get that from the InputBox. So when you do several things on a line, like: x = 14 + y; You need to be aware of the order of things. First we add 14 and y. Then we put the result (what it evaluates to, or returns) into x. That's my goal, to have a bunch of these cool examples to demonstrate and teach the class while they have fun. I tried this example on my roommate and while I may not use this as the first lesson, she liked it and learned something. Some cool mathematica programs that make beautiful graphs or shapes that are easy to understand would be good ideas and I'm going to look into those. Here are some complicated actionscript examples but that's a bit too advanced and I can't teach flash. What other ideas do you have?

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• JavaScript issues

  - by Michael

  My java scirpt is not working right. It is simple pre-vailidation form and I can not get the script to work. It is supposed to validate each field but I can not get it to validate past the first name. I stripped out all of the other garbage so the code would not be confusing Should be a copy paste to notepad. Little help please <?xml version="1.0" encoding="iso-8859-1"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <script language="JavaScript" type="text/javascript"> <!-- function validateForm(theForm) { var name = theForm.firstname.value; var name = theForm.lastname.value; var email = theForm.email.value; if (name == "") { alert("Please fill in your First Name."); theForm.firstname.focus(); return false; } if (name == "") { alert("Please fill in your Last Name."); theForm.lastname.focus(); return false; } if (email == "") { alert("Please fill in your email address."); theForm.email.focus(); return false; } return true; } //--> </script> if (!theForm.myCheckbox1.checked { alert("Please check the honor box."); return false; } </head> <body> </script> <fieldset> <legend>Fun in the Sun With JavaScirpt</legend> <ul> <form action="blah.cgi" method="post" onSubmit="return validateForm(this);"> First name: <input type="text" name="firstname"> <font color="#FF0000" size="1" face="Arial, Helvetica, sans-serif"><strong>*</strong></font> <br><br> Last name: <input type="text" name="lastname"> <font color="#FF0000" size="1" face="Arial, Helvetica, sans-serif"><strong>*</strong></font> <br><br> Email address: <input type="text" name="email"> <font color="#FF0000" size="1" face="Arial, Helvetica, sans-serif"><strong>*</strong></font> <br><br> Phone Number: <input type="text" name="phone"><br><br> <input type="submit" name="submit" value="Submit"> </form> <input type="checkbox" name="myCheckbox" value="someValue"><font color="#FF0000" size="1" face="Arial, Helvetica, sans-serif"><strong>*</strong></font> <P>By checking this Box you are confirming the data is accurate</p> <p>(* indicates a required field)</p> </body> </html>

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• Mercurial "hg clone" on Windows via ssh with plink issue

  - by Kyle Tolle

  I have a Windows Server 2008 machine (iis7) that has CopSSH set up on it. To connect to it, I have a Windows 7 machine with Mercurial 1.5.1 (and TortoiseHg) installed. I can connect to the server using PuTTY with a non-standard ssh port and a .ppk file just fine. So I know the server can be SSH'd into. Next, I wanted to use the CLI to connect via hg clone to get a private repo. I've seen elsewhere that you need to have ssh configured in your mercurial.ini file, so my mercurial.ini has a line: ssh = plink.exe -ssh -C -l username -P #### -i "C:/Program Files/PuTTY/Key Files/KyleKey.ppk" Note: username is filled in with the username I set up via copSSH. #### is filled in with the non-standard ssh port I've defined for copSSH. I try to do the command hg clone ssh://inthom.com but I get this error: remote: bash: inthom.com: command not found abort: no suitable response from remote hg! It looks like hg or plink parses the hostname such that it thinks that inthom.com is a command instead of the server to ssh to. That's really odd. Next, I tried to just use plink to connect by plink -P #### ssh://inthom.com, and I am then prompted for my username, and next password. I enter them both and then I get this error: bash: ssh://inthom.com: No such file or directory So now it looks like plink doesn't parse the hostname correctly. I fiddled around for a while trying to figure out how to do call hg clone with an empty ssh:// field and eventually figured out that this command allows me to reach the server and clone a test repo on the inthom.com server: hg clone ssh://!/Repos/test ! is the character I've found that let's me leave the hostname blank, but specify the repo folder to clone. What I really don't understand is how plink knows what server to ssh to at all. neither my mercurial.ini nor the command specify a server. None of the hg clone examples I've seen have a ! character. They all use an address, which makes sense, so you can connect to any repo via ssh that you want to clone. My only guess is that it somehow defaults to the last server I used PuTTY to SSH to, but I SSH'd into another server, and then tried to use plink to get to it, but plink still defaults to inthom.com (verified with the -v arg to plink). So I am at a loss as to how plink gets this server value at all. For "fun", I tried using TortoiseHg and can only clone a repo when I use ssh://!/Repos/test as the Source. Now, you can see that, since plink doesn't parse the hostname correctly, I had to specify the port number and username in the mercurial.ini file, instead of in the hostname like [email protected]:#### like you'd expect to. Trying to figure this out at first drove me insane, because I would get errors that the host couldn't be reached, which I knew shouldn't be the case. My question is how can I configure my setup so that ssh://[email protected]:####/Repos/test is parsed correctly as the username, hostname, port number, and repo to copy? Is it something wrong with the version of plink that I'm using, or is there some setting I may have messed up? If it is plink's fault, is there an alternative tool I can use? I'm going to try to get my friend set up to connect to this same repo, so I'd like to have a clean solution instead of this ! business. Especially when I have no idea how plink gets this default server, so I'm not sure if he'd even be able to get to inthom.com correctly. PS. I've had to use a ton of different tutorials to even get to this stage. Therefore, I haven't tried pushing any changes to the server yet. Hopefully I'll get this figured out and then I can try pushing changes to the repo.

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• Is the Unix Philosophy still relevant in the Web 2.0 world?

  - by David Titarenco

  Introduction Hello, let me give you some background before I begin. I started programming when I was 5 or 6 on my dad's PSION II (some primitive BASIC-like language), then I learned more and more, eventually inching my way up to C, C++, Java, PHP, JS, etc. I think I'm a pretty decent coder. I think most people would agree. I'm not a complete social recluse, but I do stuff like write a virtual machine for fun. I've never taken a computer course in college because I've been in and out for the past couple of years and have only been taking core classes; never having been particularly amazing at school, perhaps I'm missing some basic tenet that most learn in CS101. I'm currently reading Coders at Work and this question is based on some ideas I read in there. A Brief (Fictionalized) Example So a certain sunny day I get an idea. I hire a designer and hammer away at some C/C++ code for a couple of months, soon thereafter releasing silvr.com, a website that transmutes lead into silver. Yep, I started my very own start-up and even gave it a clever web 2.0 name with a vowel missing. Mom and dad are proud. I come up with some numbers I should be seeing after 1, 2, 3, 6, 9, 12 months and set sail. Obviously, my transmuting server isn't perfect, sometimes it segfaults, sometimes it leaks memory. I fix it and keep truckin'. After all, gdb is my best friend. Eventually, I'm at a position where a very small community of people are happily transmuting lead into silver on a semi-regular basis, but they want to let their friends on MySpace know how many grams of lead they transmuted today. And they want to post images of their lead and silver nuggets on flickr. I'm losing out on potential traffic unless I let them log in with their Yahoo, Google, and Facebook accounts. They want webcam support and live cock fighting, merry-go-rounds and Jabberwockies. All these things seem necessary. The Aftermath Of course, I have to re-write the transmuting server! After all, I've been losing money all these months. I need OAuth libraries and OpenID libraries, JSON support, and the only stable Jabberwocky API is for Java. C++ isn't even an option anymore. I'm just one guy! The Java binary just grows and grows since I need some legacy Apache include for the JSON library, and some antiquated Sun dependency for OAuth support. Then I pick up a book like Coders at Work and read what people like jwz say about complexity... I think to myself.. Keep it simple, stupid. I like simple things. I've always loved the Unix Philosophy but even after trying to keep the new server source modular and sleek, I loathe having to write one more line of code. It feels that I'm just piling crap on top of other crap. Maybe I'm naive thinking every piece of software can be simple and clever. Maybe it's just a phase.. or is the Unix Philosophy basically dead when it comes to the current state of (web) development? I'm just kind of disheartened :(

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• Anyone willing to help out a javascript n00b? :-)

  - by Splynx

  Since I am asking for a lot, and know it, the following is a wall of text for those who might show some interest and want to know a little before offering their help to me. First a little about my level of programming skills, and a little about what I ask for. Where I'm at: I am not totally new to Javascript, and have dabbled a little with PHP earlier - well have dabbled a lot with PHP in fact, but never got good at it because I program alone. And I have until now never used forums to get help etc. other that searching to see if anyone else had my problem before and what the solution was. So I am not a intuitive or talented programmer, I'm more of a very maticulate programmer and you would be surprised how far you can get with if else... (ok that's a joke hehe). My solutions are usually (I am guessing here) not the best ones - and slow I take it, and the code is usually too long and I have to look up most of the stuff I use (really a lot of it is not done in "freehand"). I have a LOT of experience with HTML and CSS, and have always done well formed markup, as well as I am really into x-browsing and always require that my work validates when it's done. I also worry about optimizing a lot, and work with sprites for images, minimize the number of http requests etc, using H1,H2 etc. where it is logically correct, as well as use the correct elements and not just div span or p it... So because I am a workhorse and very maticulate I can actually pull off some quite "advanced" features, but it's always the basics that bite me in the end. Not fully understanding the syntax and so on usually gives me problems. Have recently discovered jQuery - wich is a lot of fun.... But I want to use it for the DOM node manipulation/handling only. As I mentioned I worry about optimizing, and jQuery used for everything seems... well not optimal, it strikes me as doing it yourself when possible is faster than accesing another script that may take a whole lot of other considerations into perspective when handling your variables and objects (and I am just guessing here since I as explained know nothing). So thats where I'm at... As mentioned I just started with javascript for "real" so I do not have much to show, but at the end of my WOT you can see two unfinisheded scripts I have made so you can see where I'm at roughly - just check out the URL without the /feedback.html for the second example (I am only allowed to post 1 link since I am also a SO n00b) (and for those rushing over to a validation service, remember I wrote "when it's done"...) What I ask for: I am figuring this... I have a piece of code I am working on at the moment, and this little project has taught me a whole lot already, and I have "grown" a lot as a javascript programmer. If I add a whole lot of comments to the script, and explain what it is intended to do, will you then show me where: I am writing incorrect code - making mistakes Where/how my code could be more optimal Where I am just simply being a muppet The code I want to use as the background for the tuition is the one here http://projects.1000monkeys.dk/feedback.html Use firebug and have a quick look see...

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• Can a conforming C implementation #define NULL to be something wacky

  - by janks

  I'm asking because of the discussion that's been provoked in this thread: http://stackoverflow.com/questions/2597142/when-was-the-null-macro-not-0/2597232 Trying to have a serious back-and-forth discussion using comments under other people's replies is not easy or fun. So I'd like to hear what our C experts think without being restricted to 500 characters at a time. The C standard has precious few words to say about NULL and null pointer constants. There's only two relevant sections that I can find. First: 3.2.2.3 Pointers An integral constant expression with the value 0, or such an expression cast to type void * , is called a null pointer constant. If a null pointer constant is assigned to or compared for equality to a pointer, the constant is converted to a pointer of that type. Such a pointer, called a null pointer, is guaranteed to compare unequal to a pointer to any object or function. and second: 4.1.5 Common definitions <stddef.h> The macros are NULL which expands to an implementation-defined null pointer constant; The question is, can NULL expand to an implementation-defined null pointer constant that is different from the ones enumerated in 3.2.2.3? In particular, could it be defined as: #define NULL __builtin_magic_null_pointer Or even: #define NULL ((void*)-1) My reading of 3.2.2.3 is that it specifies that an integral constant expression of 0, and an integral constant expression of 0 cast to type void* must be among the forms of null pointer constant that the implementation recognizes, but that it isn't meant to be an exhaustive list. I believe that the implementation is free to recognize other source constructs as null pointer constants, so long as no other rules are broken. So for example, it is provable that #define NULL (-1) is not a legal definition, because in if (NULL) do_stuff(); do_stuff() must not be called, whereas with if (-1) do_stuff(); do_stuff() must be called; since they are equivalent, this cannot be a legal definition of NULL. But the standard says that integer-to-pointer conversions (and vice-versa) are implementation-defined, therefore it could define the conversion of -1 to a pointer as a conversion that produces a null pointer. In which case if ((void*)-1) would evaluate to false, and all would be well. So what do other people think? I'd ask for everybody to especially keep in mind the "as-if" rule described in 2.1.2.3 Program execution. It's huge and somewhat roundabout, so I won't paste it here, but it essentially says that an implementation merely has to produce the same observable side-effects as are required of the abstract machine described by the standard. It says that any optimizations, transformations, or whatever else the compiler wants to do to your program are perfectly legal so long as the observable side-effects of the program aren't changed by them. So if you are looking to prove that a particular definition of NULL cannot be legal, you'll need to come up with a program that can prove it. Either one like mine that blatantly breaks other clauses in the standard, or one that can legally detect whatever magic the compiler has to do to make the strange NULL definition work. Steve Jessop found an example of way for a program to detect that NULL isn't defined to be one of the two forms of null pointer constants in 3.2.2.3, which is to stringize the constant: #define stringize_helper(x) #x #define stringize(x) stringize_helper(x) Using this macro, one could puts(stringize(NULL)); and "detect" that NULL does not expand to one of the forms in 3.2.2.3. Is that enough to render other definitions illegal? I just don't know. Thanks!

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• Is it possible to embed Cockburn style textual UML Use Case content in the code base to improve code

  - by fooledbyprimes

  experimenting with Cockburn use cases in code I was writing some complicated UI code. I decided to employ Cockburn use cases with fish,kite,and sea levels (discussed by Martin Fowler in his book 'UML Distilled'). I wrapped Cockburn use cases in static C# objects so that I could test logical conditions against static constants which represented steps in a UI workflow. The idea was that you could read the code and know what it was doing because the wrapped objects and their public contants gave you ENGLISH use cases via namespaces. Also, I was going to use reflection to pump out error messages that included the described use cases. The idea is that the stack trace could include some UI use case steps IN ENGLISH.... It turned out to be a fun way to achieve a mini,psuedo light-weight Domain Language but without having to write a DSL compiler. So my question is whether or not this is a good way to do this? Has anyone out there ever done something similar? c# example snippets follow Assume we have some aspx page which has 3 user controls (with lots of clickable stuff). User must click on stuff in one particular user control (possibly making some kind of selection) and then the UI must visually cue the user that the selection was successful. Now, while that item is selected, the user must browse through a gridview to find an item within one of the other user controls and then select something. This sounds like an easy thing to manage but the code can get ugly. In my case, the user controls all sent event messages which were captured by the main page. This way, the page acted like a central processor of UI events and could keep track of what happens when the user is clicking around. So, in the main aspx page, we capture the first user control's event. using MyCompany.MyApp.Web.UseCases; protected void MyFirstUserControl_SomeUIWorkflowRequestCommingIn(object sender, EventArgs e) { // some code here to respond and make "state" changes or whatever // // blah blah blah // finally we have this (how did we know to call fish level method?? because we knew when we wrote the code to send the event in the user control) UpdateUserInterfaceOnFishLevelUseCaseGoalSuccess(FishLevel.SomeNamedUIWorkflow.SelectedItemForPurchase) } protected void UpdateUserInterfaceOnFishLevelGoalSuccess(FishLevel.SomeNamedUIWorkflow goal) { switch (goal) { case FishLevel.SomeNamedUIWorkflow.NewMasterItemSelected: //call some UI related methods here including methods for the other user controls if necessary.... break; case FishLevel.SomeNamedUIWorkFlow.DrillDownOnDetails: //call some UI related methods here including methods for the other user controls if necessary.... break; case FishLevel.SomeNamedUIWorkFlow.CancelMultiSelect: //call some UI related methods here including methods for the other user controls if necessary.... break; // more cases... } } } //also we have protected void UpdateUserInterfaceOnSeaLevelGoalSuccess(SeaLevel.SomeNamedUIWorkflow goal) { switch (goal) { case SeaLevel.CheckOutWorkflow.ChangedCreditCard: // do stuff // more cases... } } } So, in the MyCompany.MyApp.Web.UseCases namespace we might have code like this: class SeaLevel... class FishLevel... class KiteLevel... The workflow use cases embedded in the classes could be inner classes or static methods or enumerations or whatever gives you the cleanest namespace. I can't remember what I did originally but you get the picture.

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• Code golf: Word frequency chart

  - by ChristopheD

  The challenge: Build an ASCII chart of the most commonly used words in a given text. The rules: Only accept a-z and A-Z (alphabetic characters) as part of a word. Ignore casing (She == she for our purpose). Ignore the following words (quite arbitary, I know): the, and, of, to, a, i, it, in, or, is Clarification: considering don't: this would be taken as 2 different 'words' in the ranges a-z and A-Z: (don and t). Optionally (it's too late to be formally changing the specifications now) you may choose to drop all single-letter 'words' (this could potentially make for a shortening of the ignore list too). Parse a given text (read a file specified via command line arguments or piped in; presume us-ascii) and build us a word frequency chart with the following characteristics: Display the chart (also see the example below) for the 22 most common words (ordered by descending frequency). The bar width represents the number of occurences (frequency) of the word (proportionally). Append one space and print the word. Make sure these bars (plus space-word-space) always fit: bar + [space] + word + [space] should be always <= 80 characters (make sure you account for possible differing bar and word lenghts: e.g.: the second most common word could be a lot longer then the first while not differing so much in frequency). Maximize bar width within these constraints and scale the bars appropriately (according to the frequencies they represent). An example: The text for the example can be found here (Alice's Adventures in Wonderland, by Lewis Carroll). This specific text would yield the following chart: _________________________________________________________________________ |_________________________________________________________________________| she |_______________________________________________________________| you |____________________________________________________________| said |____________________________________________________| alice |______________________________________________| was |__________________________________________| that |___________________________________| as |_______________________________| her |____________________________| with |____________________________| at |___________________________| s |___________________________| t |_________________________| on |_________________________| all |______________________| this |______________________| for |______________________| had |_____________________| but |____________________| be |____________________| not |___________________| they |__________________| so For your information: these are the frequencies the above chart is built upon: [('she', 553), ('you', 481), ('said', 462), ('alice', 403), ('was', 358), ('that ', 330), ('as', 274), ('her', 248), ('with', 227), ('at', 227), ('s', 219), ('t' , 218), ('on', 204), ('all', 200), ('this', 181), ('for', 179), ('had', 178), (' but', 175), ('be', 167), ('not', 166), ('they', 155), ('so', 152)] A second example (to check if you implemented the complete spec): Replace every occurence of you in the linked Alice in Wonderland file with superlongstringstring: ________________________________________________________________ |________________________________________________________________| she |_______________________________________________________| superlongstringstring |_____________________________________________________| said |______________________________________________| alice |________________________________________| was |_____________________________________| that |______________________________| as |___________________________| her |_________________________| with |_________________________| at |________________________| s |________________________| t |______________________| on |_____________________| all |___________________| this |___________________| for |___________________| had |__________________| but |_________________| be |_________________| not |________________| they |________________| so The winner: Shortest solution (by character count, per language). Have fun! Edit: Table summarizing the results so far (2012-02-15) (originally added by user Nas Banov): Language Relaxed Strict ========= ======= ====== GolfScript 130 143 Perl 185 Windows PowerShell 148 199 Mathematica 199 Ruby 185 205 Unix Toolchain 194 228 Python 183 243 Clojure 282 Scala 311 Haskell 333 Awk 336 R 298 Javascript 304 354 Groovy 321 Matlab 404 C# 422 Smalltalk 386 PHP 450 F# 452 TSQL 483 507 The numbers represent the length of the shortest solution in a specific language. "Strict" refers to a solution that implements the spec completely (draws |____| bars, closes the first bar on top with a ____ line, accounts for the possibility of long words with high frequency etc). "Relaxed" means some liberties were taken to shorten to solution. Only solutions shorter then 500 characters are included. The list of languages is sorted by the length of the 'strict' solution. 'Unix Toolchain' is used to signify various solutions that use traditional *nix shell plus a mix of tools (like grep, tr, sort, uniq, head, perl, awk).

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• translating play in HTML to python

  - by aharon

  So, I'd like to represent one of Shakespeare's plays, Hamlet, into the following objects (maybe this isn't the best representation, if so please tell me): class Play(): acts = [] ... def add_act(self, act): acts.append(act) class Act(): scenes = [] ... def add_scene(self, scene): scenes.append(scene) class Scene(): elems = [] def __init__(self, title, setting=""): ... def add_elem(self, elem): elems.append(elem) ... class StageDirection(): # elem def __init__(self, text): ... class Line(): # elem def __init__(self, id, text, character = None): ... # A None character represents a continuation from the previous line # id could be, for example, 1.1.1 There are other methods, of course, for printing and such in each of the classes. The question is, how do I get a structure based on these classes (or something like them) from HTML 4 code that looks like this: <H3>ACT I</h3> <h3>SCENE I. Elsinore. A platform before the castle.</h3> <p><blockquote> <i>FRANCISCO at his post. Enter to him BERNARDO</i> </blockquote> <A NAME=speech1><b>BERNARDO</b></a> <blockquote> <A NAME=1.1.1>Who's there?</A><br> </blockquote> <A NAME=speech2><b>FRANCISCO</b></a> <blockquote> <A NAME=1.1.2>Nay, answer me: stand, and unfold yourself.</A><br> </blockquote> <A NAME=speech3><b>BERNARDO</b></a> <blockquote> <A NAME=1.1.3>Long live the king!</A><br> </blockquote> <A NAME=speech4><b>FRANCISCO</b></a> <blockquote> <A NAME=1.1.4>Bernardo?</A><br> </blockquote> <A NAME=speech5><b>BERNARDO</b></a> <blockquote> <A NAME=1.1.5>He.</A><br> </blockquote> <!-- for more, see the source of shakespeare.mit.edu/hamlet/full.html --> translating that into something like this: play = Play() actI = Act() sceneI = Scene("Scene I", "Elsinore. A platform before the castle.") sceneI.add_elem(StageDirection("Francisco at his post. Enter to him Bernardo.")) sceneI.add_elem(Line("Bernardo", "Who's there?")) ... Of course, I don't expect all the code—but what libraries and, when there aren't libraries, logic should I use? Thanks. (This is for a future opensource project and me learning Python for fun—not homework.)

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• Use QuickCheck by generating primes

  - by Dan

  Background For fun, I'm trying to write a property for quick-check that can test the basic idea behind cryptography with RSA. Choose two distinct primes, p and q. Let N = p*q e is some number relatively prime to (p-1)(q-1) (in practice, e is usually 3 for fast encoding) d is the modular inverse of e modulo (p-1)(q-1) For all x such that 1 < x < N, it is always true that (x^e)^d = x modulo N In other words, x is the "message", raising it to the eth power mod N is the act of "encoding" the message, and raising the encoded message to the dth power mod N is the act of "decoding" it. (The property is also trivially true for x = 1, a case which is its own encryption) Code Here are the methods I have coded up so far: import Test.QuickCheck -- modular exponentiation modExp :: Integral a => a -> a -> a -> a modExp y z n = modExp' (y `mod` n) z `mod` n where modExp' y z | z == 0 = 1 | even z = modExp (y*y) (z `div` 2) n | odd z = (modExp (y*y) (z `div` 2) n) * y -- relatively prime rPrime :: Integral a => a -> a -> Bool rPrime a b = gcd a b == 1 -- multiplicative inverse (modular) mInverse :: Integral a => a -> a -> a mInverse 1 _ = 1 mInverse x y = (n * y + 1) `div` x where n = x - mInverse (y `mod` x) x -- just a quick way to test for primality n `divides` x = x `mod` n == 0 primes = 2:filter isPrime [3..] isPrime x = null . filter (`divides` x) $ takeWhile (\y -> y*y <= x) primes -- the property prop_rsa (p,q,x) = isPrime p && isPrime q && p /= q && x > 1 && x < n && rPrime e t ==> x == (x `powModN` e) `powModN` d where e = 3 n = p*q t = (p-1)*(q-1) d = mInverse e t a `powModN` b = modExp a b n (Thanks, google and random blog, for the implementation of modular multiplicative inverse) Question The problem should be obvious: there are way too many conditions on the property to make it at all usable. Trying to invoke quickCheck prop_rsa in ghci made my terminal hang. So I've poked around the QuickCheck manual a bit, and it says: Properties may take the form forAll <generator> $ \<pattern> -> <property> How do I make a <generator> for prime numbers? Or with the other constraints, so that quickCheck doesn't have to sift through a bunch of failed conditions? Any other general advice (especially regarding QuickCheck) is welcome.

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• Why do I get a segmentation fault while redirecting sys.stdout to Tkinter.Text widget in Python?

  - by Brent Nash

  I'm in the process of building a GUI-based application with Python/Tkinter that builds on top of the existing Python bdb module. In this application, I want to silence all stdout/stderr from the console and redirect it to my GUI. To accomplish this purpose, I've written a specialized Tkinter.Text object (code at the end of the post). The basic idea is that when something is written to sys.stdout, it shows up as a line in the "Text" with the color black. If something is written to sys.stderr, it shows up as a line in the "Text" with the color red. As soon as something is written, the Text always scrolls down to view the most recent line. I'm using Python 2.6.1 at the moment. On Mac OS X 10.5, this seems to work great. I have had zero problems with it. On RedHat Enterprise Linux 5, however, I pretty reliably get a segmentation fault during the run of a script. The segmentation fault doesn't always occur in the same place, but it pretty much always occurs. If I comment out the sys.stdout= and sys.stderr= lines from my code, the segmentation faults seem to go away. I'm sure there are other ways around this that I will probably have to resort to, but can anyone see anything I'm doing blatantly wrong here that could be causing these segmentation faults? It's driving me nuts. Thanks! PS - I realize redirecting sys.stderr to the GUI might not be a great idea, but I still get segmentation faults even when I only redirect sys.stdout and not sys.stderr. I also realize that I'm allowing the Text to grow indefinitely at the moment. class ConsoleText(tk.Text): '''A Tkinter Text widget that provides a scrolling display of console stderr and stdout.''' class IORedirector(object): '''A general class for redirecting I/O to this Text widget.''' def __init__(self,text_area): self.text_area = text_area class StdoutRedirector(IORedirector): '''A class for redirecting stdout to this Text widget.''' def write(self,str): self.text_area.write(str,False) class StderrRedirector(IORedirector): '''A class for redirecting stderr to this Text widget.''' def write(self,str): self.text_area.write(str,True) def __init__(self, master=None, cnf={}, **kw): '''See the __init__ for Tkinter.Text for most of this stuff.''' tk.Text.__init__(self, master, cnf, **kw) self.started = False self.write_lock = threading.Lock() self.tag_configure('STDOUT',background='white',foreground='black') self.tag_configure('STDERR',background='white',foreground='red') self.config(state=tk.DISABLED) def start(self): if self.started: return self.started = True self.original_stdout = sys.stdout self.original_stderr = sys.stderr stdout_redirector = ConsoleText.StdoutRedirector(self) stderr_redirector = ConsoleText.StderrRedirector(self) sys.stdout = stdout_redirector sys.stderr = stderr_redirector def stop(self): if not self.started: return self.started = False sys.stdout = self.original_stdout sys.stderr = self.original_stderr def write(self,val,is_stderr=False): #Fun Fact: The way Tkinter Text objects work is that if they're disabled, #you can't write into them AT ALL (via the GUI or programatically). Since we want them #disabled for the user, we have to set them to NORMAL (a.k.a. ENABLED), write to them, #then set their state back to DISABLED. self.write_lock.acquire() self.config(state=tk.NORMAL) self.insert('end',val,'STDERR' if is_stderr else 'STDOUT') self.see('end') self.config(state=tk.DISABLED) self.write_lock.release()

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• ASP.NET GridView - Cannot set the colour of the row during databind?

  - by Dan

  This is driving me NUTS! It's something that I've done 100s of time with a Datagrid. I'm now using a Gridview and I can't figure this out. I've got this grid: <asp:GridView AutoGenerateColumns="false" runat="server" ID="gvSelect" CssClass="GridViewStyle" GridLines="None" ShowHeader="False" PageSize="20" AllowPaging="True"> <Columns> <asp:TemplateField> <ItemTemplate> <asp:Label runat="server" ID="lbldas" Text="blahblah"></asp:Label> </ItemTemplate> </asp:TemplateField> </Columns> And during the RowDataBound I've tried: Protected Sub gvSelect_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles gvSelect.RowCreated If e.Row.RowType = DataControlRowType.DataRow Then e.Row.Attributes.Add("onMouseOver", "this.style.backgroundColor='lightgrey'") End If End Sub And it NEVER sets the row backcolor.. I've been successful in using: gridrow.Cells(0).BackColor = Drawing.Color.Blue But doing the entire row? NOPE! and it's driving me nuts.. does ANYONE have solution for me? And just for fun I put this on the SAME page: <asp:DataGrid AutoGenerateColumns="false" runat="server" ID="dgSelect" GridLines="None" ShowHeader="False" PageSize="20" AllowPaging="True"> <Columns> <asp:TemplateColumn> <ItemTemplate> <asp:Label runat="server" ID="lbldas" Text="blahblah"></asp:Label> </ItemTemplate> </asp:TemplateColumn> </Columns> </asp:DataGrid> And in the ItemDataBound I put: If Not e.Item.ItemType = ListItemType.Header And Not e.Item.ItemType = ListItemType.Footer Then e.Item.Attributes.Add("onMouseOver", "this.style.backgroundColor='lightgrey'") End If And it works as expected.. SO What am I doing wrong with the Gridview? UPDATE ************** I thought I'd post the resulting HTML to show that any styles aren't affecting this. Here's the gridview html: <div class="AspNet-GridView" id="gvSelect"> <table cellpadding="0" cellspacing="0" summary=""> <tbody> <tr> <td> <span id="gvSelect_ctl02_lbldas">blahblah</span> </td> </tr> </tbody> </table> </div> And here's the resulting Datagrid HTML: <table cellspacing="0" border="0" id="dgSelect" style="border-collapse:collapse;"> <tr onMouseOver="this.style.backgroundColor='lightgrey'"> <td> <span id="dgSelect_ctl03_lbldas">blahblah</span> </td> </tr> </table> See.. the main difference is the tag. It never gets set in the gridview.. and I don't know why.. I've traced through it.. and the code gets run.. :S

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