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• Is it reasonable to insist on reproducing every defect before diagnosing and fixing it?

  - by amphibient

  I work for a software product company. We have large enterprise customers who implement our product and we provide support to them. For example, if there is a defect, we provide patches, etc. In other words, It is a fairly typical setup. Recently, a ticket was issued and assigned to me regarding an exception that a customer found in a log file and that has to do with concurrent database access in a clustered implementation of our product. So the specific configuration of this customer may well be critical in the occurrence of this bug. All we got from the customer was their log file. The approach I proposed to my team was to attempt to reproduce the bug in a similar configuration setup as that of the customer and get a comparable log. However, they disagree with my approach saying that I should not need to reproduce the bug (as that is overly time-consuming and will require simulating a server cluster on VMs) and that I should simply "follow the code" to see where the thread- and/or transaction-unsafe code is and put the change working off of a simple local development, which is not a cluster implementation like the environment from which the occurrence of the bug originates. To me, working out of an abstract blueprint (program code) rather than a concrete, tangible, visible manifestation (runtime reproduction) seems like a difficult working environment (for a person of normal cognitive abilities and attention span), so I wanted to ask a general question: Is it reasonable to insist on reproducing every defect and debug it before diagnosing and fixing it? Or: If I am a senior developer, should I be able to read (multithreaded) code and create a mental picture of what it does in all use case scenarios rather than require to run the application, test different use case scenarios hands on, and step through the code line by line? Or am I a poor developer for demanding that kind of work environment? Is debugging for sissies? In my opinion, any fix submitted in response to an incident ticket should be tested in an environment simulated to be as close to the original environment as possible. How else can you know that it will really remedy the issue? It is like releasing a new model of a vehicle without crash testing it with a dummy to demonstrate that the air bags indeed work. Last but not least, if you agree with me: How should I talk with my team to convince them that my approach is reasonable, conservative and more bulletproof?

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• EF Doesn't Like Same Named Tables

  - by Anthony Trudeau

  Originally posted on: http://geekswithblogs.net/tonyt/archive/2013/07/02/153327.aspxIt's another week and another restriction imposed by the Entity Framework (EF). Don't get me wrong. I like EF, but I don't like how it restricts you in different ways. At this point you may be asking yourself the question: how can you have more than one table with the same name?The answer is to have tables in different schemas. I do this to partition the data based on the area of concern. It allows security to be assigned conveniently. A lot of people don't use schemas. I love them. But this article isn't about schemas.In the situation I have two tables:Contact.PersonEmployee.PersonThe first contains the basic, more public information such as the name. The second contains mostly HR specific information. I then mapped these tables to two classes. I stuck to a Table per Class (TPC) mapping, because of problems I've had in the past implementing inheritance with EF. The following code gives you the basic contents of the classes.[Table("Person", Schema = "Employee")]public class Employee {   ...   public int PersonId { get; set; }   [ForeignKey("PersonId")]   public virtual Person Person { get; set; }}[Table("Person", Schema = "Contact")]public class Person {   [Key]   public int Id { get; set; }   ...}This seemingly simple scenario just doesn't work. The problem occurs when you try to add a Person to the DbContext. You get an InvalidOperationException with the following text:The entity types 'Employee' and 'Person' cannot share table 'People' because they are not in the same type hierarchy or do not have a valid one to one foreign key relationship with matching primary keys between them..This is interesting for a couple of reasons. First, there is no People table in my database. Second, I have used the SetInitializer method to stop a database from being created, so it shouldn't be thinking about new tables.The solution to my problem was to change the name of my Employee.Person table. I decided to name it Employee.Employee. It's not ideal, but it gets me past the EF limitation. I hope that this article will help someone else that has the same problem.

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• I have a performance problem

  - by Alan

  (copied from my wordpress blog). So start 95% of the performance calls that I receive. They usually continue something like: I have gathered some *stat data for you (eg the guds tool from Document 1285485.1), can you please root cause our problem? So, do you think you could? Neither can I, based on this my answer inevitably has to be "No". Given this kind of problem statement, I have no idea about the expectations, the boundary conditions, or even the application. The answer may as well be "Performance problems? Consult your local Doctor for Viagra". It's really not a lot to go on. So, What kind of problem description is going to allow me to start work on the issue that is being seen? I don't doubt that there really is an issue, it just needs to be pinned down somewhat. What behavior exactly are you expecting to see? Be specific and use business metrics. For example "run-time", "response-time" and "throughput". This helps us define exit criterea. Now, let's look at the system that is having problems. How is what you are seeing different? Use the same type of metrics. The answers to these two questions take us a long way towards being able to work a call. Even more helpful are answers to questions like Has this system ever worked to expectation? If so, when did it start exhibiting this behavior? Is the problem always present, or does it sometimes work to expectation? If it sometimes works to expectation, when are you seeing the problem? Is there any discernible pattern? Is the impact of the problem getting better, worse, or remaining constant? What kind of differences are there between when the system was performing to expectation and when it is not? Are there other machines where we could expect to see the same issue (eg similar usage and load), but are not? Again, differences? Once we start to gather information like this we start to build up a much clearer picture of exactly what we need to investigate, and what we need to achieve so that both you and me agree that the problem has been solved. Please help get that figure of poorly defined problem statements down from it's current 95% value.

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• Using extension methods to decrease the surface area of a C# interface

  - by brian_ritchie

  An interface defines a contract to be implemented by one or more classes.  One of the keys to a well-designed interface is defining a very specific range of functionality. The profile of the interface should be limited to a single purpose & should have the minimum methods required to implement this functionality.  Keeping the interface tight will keep those implementing the interface from getting lazy & not implementing it properly.  I've seen too many overly broad interfaces that aren't fully implemented by developers.  Instead, they just throw a NotImplementedException for the method they didn't implement. One way to help with this issue, is by using extension methods to move overloaded method definitions outside of the interface. Consider the following example: .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: Consolas, "Courier New", Courier, Monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } 1: public interface IFileTransfer 2: { 3: void SendFile(Stream stream, Uri destination); 4: } 5:   6: public static class IFileTransferExtension 7: { 8: public static void SendFile(this IFileTransfer transfer, 9: string Filename, Uri destination) 10: { 11: using (var fs = File.OpenRead(Filename)) 12: { 13: transfer.SendFile(fs, destination); 14: } 15: } 16: } 17:   18: public static class TestIFileTransfer 19: { 20: static void Main() 21: { 22: IFileTransfer transfer = new FTPFileTransfer("user", "pass"); 23: transfer.SendFile(filename, new Uri("ftp://ftp.test.com")); 24: } 25: } In this example, you may have a number of overloads that uses different mechanisms for specifying the source file. The great part is, you don't need to implement these methods on each of your derived classes.  This gives you a better interface and better code reuse.

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• Which one to select for my future career; Java, C#, Azure or Apex?

  - by user636195

  Hi folks, This time, I am going to studying Masters in Computer Science in U.S.A after a week. I have been doing my B.Sc for the past three years and after my freshman year I started working on projects (in C# and very rarely in Java) for the past two years.(i.e while I was a second and third year student). Now I am in a college where all of the programming courses are going to be taken in Java only (using Eclipse) and I am going to stay in this college for 8 months on campus and then fully employed for two years in other companies as a CPT. I really love to work on Microsoft products because, for me, they are simple and easy to use and understand. My future plan is to work in Cloud computing and be a Cloud based business owner in the near future. Since the college is going to teach us and let us do every project in Java, I was confused which programming language to use that will help me and enhance me in my career, and of course I wanted to select the one I liked to do everytime. I also heard a lot about Azure (Microsoft’s ) and Apex (Salesforce.com’s cloud computing programming language). Would you please give me your advice and recommendation based on my situation? Should I have to study only Java, or should I have to study C# or Azure beside Java on my own? The reason I asked this is because, since I have no clue how Azure works and how long it will take me to know the language, I am really confused which one to select (Java Vs C# and Azure Vs Apex or if there is any popular and mostly used Cloud Computing langauge). Do you think I can get a job in cloud computing if I study Azure or Apex by my own without experience? There is also one issue I want to consider which is a short term issue is. i.e Salary. Since I have to pay my student loan, I also need to get a good job which will let me pay my loan within two years. But, as I said, my long term plan is, get experience in Cloud Computing (from programming to administrative part,i.e every area of cloud computing) and then have my own business may be within 5-10 years. What do you think? Thank you for your time.

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• Usage of Pirated software at a company

  - by hakesh

  Hi, I am redirected from stack over flow since the topic is ethics rather than about programming. Thank you for letting me know that. and please give me advices. So, I started to work at a company as an engineer a couple of months ago. It's a small company and what they basically do is answering service on phones. Now they are switching from normal phones to IP phones so that computers take more important place in the work. However, all the computers used by workers are equipped with pirated software ,even their operating systems are. Moreover, they don't even buy one license to make copies for other computers. In other words, they do not spend any money for the software in office. I am not saying copying a licensed one is legit, but the situation is too much. There is one guy who did installing those pirated soft. He does not feel any sense of guilt and even justified when I asked about it. and he is not even a specialist. He just searched on the internet to install pirated software. Our boss does not have any knowledge of computers, so he took cheaper way. How do you guys think about this? Since I am still new to the company, I am not doing maintenance or managing on those cracked computers. But I have to use those software daily. And later on I will be doing support, help desk kind of staff. I really don't want to take responsibility for operating pirated software. and from an aspect of developer and engineer, pirated software are not able to get legal support and it may work unexpectedly. So, I am thinking about changing job. Am I thinking too much? should I wait until I have more credit from the boss and try to change his policy? So far, the boss does not take any words from me. Any opinions are welcome. Thank you

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• No Sound in 12.04 on Acer TimelineX 3830TG

  - by Fawkes5

  When i first installed ubuntu 12.04 everything worked fine. All of a sudden my sound has stopped working!! This has happened before [like 2 days ago], however the next day it started working again. That may happen again...[I've already rebooted 5 times] My Sound Card is a HDA intel PCH My Sound Chip is Intel CougarPoint HDMI My machine is an Acer TimelineX 3830TG, heres my lcpci output 00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09) 00:01.0 PCI bridge: Intel Corporation Xeon E3-1200/2nd Generation Core Processor Family PCI Express Root Port (rev 09) 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) 00:16.0 Communication controller: Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1 (rev 04) 00:1a.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2 (rev 04) 00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 04) 00:1c.0 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b4) 00:1c.1 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 2 (rev b4) 00:1c.2 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 3 (rev b4) 00:1c.3 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 4 (rev b4) 00:1d.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1 (rev 04) 00:1f.0 ISA bridge: Intel Corporation HM65 Express Chipset Family LPC Controller (rev 04) 00:1f.2 SATA controller: Intel Corporation 6 Series/C200 Series Chipset Family 6 port SATA AHCI Controller (rev 04) 00:1f.3 SMBus: Intel Corporation 6 Series/C200 Series Chipset Family SMBus Controller (rev 04) 01:00.0 VGA compatible controller: NVIDIA Corporation GF108 [GeForce GT 540M] (rev ff) 02:00.0 Ethernet controller: Atheros Communications Inc. AR8151 v2.0 Gigabit Ethernet (rev c0) 03:00.0 Network controller: Atheros Communications Inc. AR9287 Wireless Network Adapter (PCI-Express) (rev 01) 04:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5116 PCI Express Card Reader (rev 01) 05:00.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 04) I'm running a dual boot with Windows 7, sound always works there. I've tried loading earlier kernels [3.2.0 ] but that hasn't helped. I've tried playing with alsamixer, unmuting and raising volume, doesn't work I've tried playing with pauvcontrol, doesnt work. Althought, strangely, when i play a song, under output i can see a bar moving implying that something is working, just the sound isn't getting through my speakers. Thus it might be a hardware problem. I've tried unistalling and reinstalling pulsaudio annd alsamixer, doesn't work [maybe made it worse...]. I've heard reverting back to kernel 3.0... works, but i'm reluctant to try that[i dont know much about kernels]. Thank you. Please tell me what other information you need. EDIT: My audio has started working again after another reboot. However this time im not connected to my external audio on startup. I will see if this is the issue next time i'm at home Edit: Connecting to external audio is not the problem.

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• How do I prevent Ubuntu gradually slowing down to a stop?

  - by user29165

  I really do not know what is causing the problem of my desktop environment (D.E.) gradually slowing down. It seems to happen in Gnome 3.2, LXDE, XFCE, and KDE. I am running Ubuntu 11.10 and this problem started happening from a fresh install. I have noticed that if I restart Gnome or otherwise re-log-in with any of the D.E.s the speed resets to normal. I don't seem to have and memory leaks that account for it and there are not any processes that are using excessive CPU cycles. Due to the symptoms I am guessing that there is an underlying package that interacts with all D.E.s that is the source of the problem. Just to clarify, in extreme situations, if I let the slowdown continue without a restart of the D.E. my system will finally get to a point where everything, even my clock, freezes. The time over which Gnome slows down (noticeably after 17 hrs) is much less than LXDE, or XFCE but eventually they freeze as well. I didn't mention Unity since I haven't used it enough to verify the problem, but I don't see why it should be different. Just in case this is relevant, I Suspend my computer rather than turn it off. I do this because of the greatly reduced load time and the 17 hrs I stated above is actual up-time, not time where the D.E. is actually active. However, the slow down does not seem to be affected by how long the computer has been in suspend mode. I know that it is possible that this problem is due to an interaction between two or more of the applications that I use and as such it may not be able to be duplicated by others. In the end I am just wondering (a) are other people experiencing this issue and (b) does anyone have some advice on where to start looking for a solution if one is not already known. I am even open to the idea of switching to the beta release of 12.04 if anyone thinks it will solve the problem. Edit: I took a video of my latest freeze that you can watch at http://youtu.be/flKUqUzCmdE, sorry about the audio. Edit: Since that video I checked my memory for errors and tried installing the proprietary video drivers. No memory errors were found and the proprietary video drivers made the display unusable so I had to uninstall them. Any thoughts?

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• Misused mke2fs and cannot boot into system

  - by surlogics

  I installed Ubuntu with WUBI in Windows 7 64bit, and I had installed Mandriva 2011 with a disk. I tried to learn Linux with Ubuntu and misused mke2fs; after I reboot my computer, Windows 7 and Ubuntu has crashed. As I have Mandriva, I boot into Mandriva and found # df -h /dev/sda7 12G 9.8G 1.5G 88% / /dev/sda2 15G 165M 14G 2% /media/logical /dev/sda6 119G 88G 32G 74% /media/2C9E85319E84F51C /dev/sda5 118G 59G 60G 50% /media/D25A6DDE5A6DBFB9 /dev/sda9 100G 188M 100G 1% /media/ae69134a-a65e-488f-ae7f-150d1b5e36a6 /dev/sda1 100M 122K 100M 1% /media/DELLUTILITY /dev/sda3 98G 81G 17G 83% /media/OS # fdisk /dev/sda Command (m for help): p Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xd24f801e Device Boot Start End Blocks Id System /dev/sda1 2048 206847 102400 6 FAT16 /dev/sda2 * 206848 30926847 15360000 7 HPFS/NTFS/exFAT /dev/sda3 30926848 235726847 102400000 7 HPFS/NTFS/exFAT /dev/sda4 235728864 976771071 370521104 f W95 Ext'd (LBA) /dev/sda5 235728896 481488895 122880000 7 HPFS/NTFS/exFAT /dev/sda6 727252992 976771071 124759040 7 HPFS/NTFS/exFAT /dev/sda7 481500243 506674034 12586896 83 Linux /dev/sda8 506674098 514851119 4088511 82 Linux swap / Solaris /dev/sda9 514851183 727246484 106197651 83 Linux Partition table entries are not in disk order I think I may used the following command mke2fs -j -L "logical"/dev/sda2 but I had forgotten what kind of partition it was before I transfered it into ext3. perhaps ntfs Data was not lost, and I can view my files as I could in Windows. In Mandriva, there are following disks: 117.2 GB hard disk, files in it is the same as my Windows D:, and Ubuntu was installed in it; 119.0 GB hard disk is my G:, with my personal files in it; 12.0 GB is the same with Mandriva / (with means root), 101.3 GB hard disk with nothing but lost+found; DELLUTILITY should be Dell computer utilities pre-installed in my computer; logical is the disk which I had spoiled, I can view nothing but lost+found; and OS is the C: in my Windows. After I boot, grub lets me choose Mandriva or Windows. I chose Windows and it tells me: FILE system type unknown, partition type 0x7 Error 13: Invalid or unsupported executable format I doubt something wrong with windows MBR or something # cat /boot/grub/menu.lst timeout 5 color black/cyan yellow/cyan gfxmenu (hd0,6)/boot/gfxmenu default 0 title linux kernel (hd0,6)/boot/vmlinuz BOOT_IMAGE=linux root=UUID=199581b7-ac7e-4c5f-9888-24c4f213cad8 nokmsboot logo.nologo quiet resume=UUID=34c546e4-9c42-4526-aa64-bbdc0e9d64fd splash=silent vga=788 initrd (hd0,6)/boot/initrd.img title linux-nonfb kernel (hd0,6)/boot/vmlinuz BOOT_IMAGE=linux-nonfb root=UUID=199581b7-ac7e-4c5f-9888-24c4f213cad8 nokmsboot resume=UUID=34c546e4-9c42-4526-aa64-bbdc0e9d64fd initrd (hd0,6)/boot/initrd.img title failsafe kernel (hd0,6)/boot/vmlinuz BOOT_IMAGE=failsafe root=UUID=199581b7-ac7e-4c5f-9888-24c4f213cad8 nokmsboot failsafe initrd (hd0,6)/boot/initrd.img title windows root (hd0,1) makeactive chainloader +1 I can boot into Linux, but not Ubuntu, it boot into Mandriva. I don't have a boot disk. Help me find a way to make it work again.

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• Flattening System.Web.UI ControlCollection

  - by evovision

  Hi,   Sometimes one may need to get a list of child controls inside specific container and don't care about the underlying hierarchy.   The result is beautifully achieved using this extension method:   using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;    public static class ControlCollectionExtensionMethods    {        public static IEnumerable<Control> FlattenedList(this ControlCollection controls)        {            foreach (Control ctrl in controls)            {                  // return parent control                   yield return ctrl;                              // and dive into child collection                   foreach (Control child in ctrl.Controls.FlattenedList())                         yield return child;            }        }    }   P.S.: don't forget about namespaces when using it in your code, if above class is wrapped into namespace, for example: Sample, the source code file with calling code must explicitly reference it: using Sample;

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• What's the best way to cache a growing database table for html generation?

  - by McLeopold

  I've got a database table which will grow in size by about 5000 rows a hour. For a key that I would be querying by, the query will grow in size by about 1 row every hour. I would like a web page to show the latest rows for a key, 50 at a time (this is configurable). I would like to try and implement memcache to keep database activity low for reads. If I run a query and create a cache result for each page of 50 results, that would work until a new entry is added. At that time, the page of latest results gets new result and the oldest results drops off. This cascades down the list of cached pages causing me to update every cache result. It seems like a poor design. I could build the cache pages backwards, then for each page requested I should get the latest 2 pages and truncate to the proper length of 50. I'm not sure if this is good or bad? Ideally, the mechanism I use to insert a new row would also know how to invalidate the proper cache results. Has someone already solved this problem in a widely acceptable way? What's the best method of doing this? EDIT: If my understanding of the MYSQL query cache is correct, it has table level granularity in invalidation. Given the fact that I have about 5000 updates before a query on a key should need to be invalidated, it seems that the database query cache would not be used. MS SQL caches execution plans and frequently accessed data pages, so it may do better in this scenario. My query is not against a single table with TOP N. One version has joins to several tables and another has sub-selects. Also, since I want to cache the html generated table, I'm wondering if a cache at the web server level would be appropriate? Is there really no benefit to any type of caching? Is the best advice really to just allow a website site query to go through all the layers and hit the database every request?

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• Getting my younger brother started on programming

  - by SmartLemon

  My younger brother is 13 years old, I started programming when I started to develop Android applications when I was 15, last year my brother gained an interest in it and he would always pestering me about letting him make something himself, so I wrote him a few tutorials and he built himself a small application that had a few buttons that did something, I think you put in your dob and it would tell you what day you were born on, he took a couple of days building up to his final application, maybe even a week, learning everything he needed. Since then he hasn't really done much more because I have been engulfed in work and such where I have my own programming problems to sort out. I told him that when he was my age (I am 17) that he should be better then me, he was a bit sceptical about this however. I dont think he has as much logical reasoning as I would think he needs to solve more complex problems, but shouldnt that just develop over time as it did with me? He has been pestering me for the past week or something to write him more tutorials, but I didn't have time. All I had with me was a playlist I had downloaded from the new boston from youtube for C++, it's about 73 videos. He is currently about 20-30 videos in, he has come to ask me a few questions about it and thats it. Should I have really properly started him with C++? Should I stop him now and start him again on python or ruby? I know that C++ shouldn't really be a beginners language, especially for someone who is only 13, by the time this question is answered will probably be up to learning about inheritance or something. Some people may see this as not a real question, but it is, and should be used as a reference for others. I want to know, should I start him on a different language whch is more easy? What language then? And would it be better for me to teach him myself (I would make time) or just continue him with the new boston? There are a few more questions throughout this question but these are the main ones. Part of the question people seem to be neglecting is me asking whether I should change what language he is learning to another, or since he is already pretty far through the tutorials should I just leave him with C++ and he can learn the other languages freely by himself?

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• Tiling Problem Solutions for Various Size "Dominoes"

  - by user67081

  I've got an interesting tiling problem, I have a large square image (size 128k so 131072 squares) with dimensons 256x512... I want to fill this image with certain grain types (a 1x1 tile, a 1x2 strip, a 2x1 strip, and 2x2 square) and have no overlap, no holes, and no extension past the image boundary. Given some probability for each of these grain types, a list of the number required to be placed is generated for each. Obviously an iterative/brute force method doesn't work well here if we just randomly place the pieces, instead a certain algorithm is required. 1) all 2x2 square grains are randomly placed until exhaustion. 2) 1x2 and 2x1 grains are randomly placed alternatively until exhaustion 3) the remaining 1x1 tiles are placed to fill in all holes. It turns out this algorithm works pretty well for some cases and has no problem filling the entire image, however as you might guess, increasing the probability (and thus number) of 1x2 and 2x1 grains eventually causes the placement to stall (since there are too many holes created by the strips and not all them can be placed). My approach to this solution has been as follows: 1) Create a mini-image of size 8x8 or 16x16. 2) Fill this image randomly and following the algorithm specified above so that the desired probability of the entire image is realized in the mini-image. 3) Create N of these mini-images and then randomly successively place them in the large image. Unfortunately there are some downfalls to this simplification. 1) given the small size of the mini-images, nailing an exact probability for the entire image is not possible. Example if I want p(2x1)=P(1x2)=0.4, the mini image may only give 0.41 as the closes probability. 2) The mini-images create a pseudo boundary where no overlaps occur which isn't really descriptive of the model this is being used for. 3) There is only a fixed number of mini-images so i'm not sure how random this really is. I'm really just looking to brainstorm about possible solutions to this. My main concern is really to nail down closer probabilities, now one might suggest I just increase the mini-image size. Well I have, and it turns out that in certain cases(p(1x2)=p(2x1)=0.5) the mini-image 16x16 isn't even iteratively solvable.. So it's pretty obvious how difficult it is to randomly solve this for anything greater than 8x8 sizes.. So I'd love to hear some ideas. Thanks

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• The term "interface" in C++

  - by Flexo

  Java makes a clear distinction between class and interface. (I believe C# does also, but I have no experience with it). When writing C++ however there is no language enforced distinction between class and interface. Consequently I've always viewed interface as a workaround for the lack of multiple inheritance in Java. Making such a distinction feels arbitrary and meaningless in C++. I've always tended to go with the "write things in the most obvious way" approach, so if in C++ I've got what might be called an interface in Java, e.g.: class Foo { public: virtual void doStuff() = 0; ~Foo() = 0; }; and I then decided that most implementers of Foo wanted to share some common functionality I would probably write: class Foo { public: virtual void doStuff() = 0; ~Foo() {} protected: // If it needs this to do its thing: int internalHelperThing(int); // Or if it doesn't need the this pointer: static int someOtherHelper(int); }; Which then makes this not an interface in the Java sense anymore. Instead C++ has two important concepts, related to the same underlying inheritance problem: virtual inhertiance Classes with no member variables can occupy no extra space when used as a base "Base class subobjects may have zero size" Reference Of those I try to avoid #1 wherever possible - it's rare to encounter a scenario where that genuinely is the "cleanest" design. #2 is however a subtle, but important difference between my understanding of the term "interface" and the C++ language features. As a result of this I currently (almost) never refer to things as "interfaces" in C++ and talk in terms of base classes and their sizes. I would say that in the context of C++ "interface" is a misnomer. It has come to my attention though that not many people make such a distinction. Do I stand to lose anything by allowing (e.g. protected) non-virtual functions to exist within an "interface" in C++? (My feeling is the exactly the opposite - a more natural location for shared code) Is the term "interface" meaningful in C++ - does it imply only pure virtual or would it be fair to call C++ classes with no member variables an interface still?

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• PHP or C++? I just want to choose a language and focus on it!

  - by user19177

  I love C++, but I feel I don't know if I should focus on web, so PHP, or C++. It's just an hard choice because right now I want to focus on one language and don't want to switch it a few months later. With C++ I'd program in SDL, while with PHP I don't know yet. I am not a very advanced programmer but I know basics of programming and can get going very well if determined. The problem is I just don't know.. I'm like OK! I'll go for C++! Then a minute later, wait what if I went with C#? Why this that.. ! I've read milion threads about C vs VB C# Python Ruby etc, all of them which I could find! It got me nowhere. The problem is probably I need to know something from some experts I guess.. I'm sure I'm not the only one who feels/felt like I do right now yeah? Uhm... I guess I might help you with some details so your answer may be easier to write! ( And also, if you want to say something else which is not related to PHP or C++, you can do that, I've just got to the conclusion that C++ and PHP are the ones that are worth it but yeah. C# I've discarded due to some stuff I read which says in future the projects I'd start now could just be useless and stuff like that.. ) Ok well : I'm 18 years old, and I program as hobby right now, but I do hope to go to a programming college in future. ( That would be in 2 years ). Hmm, I like programming games, and I'm mostly bothered by the fact "this language could be useless to what I need to do" ( I don't know how to explain this feeling! ) I don't know which other details I could add... I hope you guys can help me choose my path, this is really stressing me I'm wasting my time not doing anything right now because I don't know which language to use..! Thanks!

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• Development Approach: User Interface In or Domain Model Out?

  - by Berin Loritsch

  While I've never delivered anything using Smalltalk, my brief time playing with it has definitely left its mark. The only way to describe the experience is MVC the way it was meant to be. Essentially, all the heavy lifting for your application is done in the business objects (or domain model if you are so inclined). The standard controls are bound to the business objects in some way. For example, a text box is mapped to an object's field (the field itself is an object so it's easy to do). A button would mapped to a method. This is all done with a very simple and natural API. We don't have to think about binding objects, etc. It just works. Yet, in many newer languages and APIs you are forced to think from the outside in. First with C++ and MFC, and now with C# and WPF, Microsoft has gotten it's developer world hooked on GUI builders where you build your application by implementing event handlers. Java Swing development isn't so different, only you are writing the code to instantiate the controls on the form yourself. For some projects, there may never even be a domain model--just event handlers. I've been in and around this model for most of my carreer. Each way forces you to think differently. With the Smalltalk approach, your domain is smart while your GUI is dumb. With the default VisualStudio approach, your GUI is smart while your domain model (if it exists) is rather anemic. Many developers that I work with see value in the Smalltalk approach, and try to shoehorn that approach into the VisualStudio environment. WPF has some dynamic binding features that makes it possible; but there are limitations. Inevitably some code that belongs in the domain model ends up in the GUI classes. So, which way do you design/develop your code? Why? GUI first. User interaction is paramount. Domain first. I need to make sure the system is correct before we put a UI on it. There's pros and cons for either approach. Domain model fits in there with crystal cathedrals and pie in the sky. GUI fits in there with quick and dirty (sometimes really dirty). And for an added bonus: How do you make sure the code is maintainable?

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• ADF Real World Developers Guide Book Review

  - by Grant Ronald

  I'm half way through my review of "Oracle ADF Real World Developer's Guide" by Jobinesh Purushothaman - unfortunately some work deadlines de-railed me from having completed my review by now but here goes.  First thing, Jobinesh works in the Oracle Product Management team with me, so is a colleague. That declaration aside, its clear that this is someone who has done the "real world" side of ADF development and that comes out in the book. In this book he addresses both the newbies and the experience developers alike.  He introduces the ADF building blocks like entity objects and view obejcts, but also goes into some of the nitty gritty details as well.  There is a pro and con to this approach; having only just learned about an entity or view object, you might then be blown away by some of the lower details of coding or lifecycle.  In that respect, you might consider this a book which you could read 3 or 4 times; maybe skipping some elements in the first read but on the next read you have a better grounding to learn the more advanced topics. One of the key issues he addresses is breaking down what happens behind the scenes.  At first, this may not seem important since you trust the framework to do everything for you - but having an understanding of what goes on is essential as you move through development.  For example, page 58 he explains the full lifecycle of what happens when you execute a query.  I think this is a great feature of his book. You see this elsewhere, for example he explains the full lifecycle of what goes on when a page is accessed : which files are involved,the JSF lifecycle etc. He also sprinkes the book with some best practices and advice which go beyond the standard features of ADF and really hits the mark in terms of "real world" advice. So in summary, this is a great ADF book, well written and covering a mass of information.  If you are brand new to ADF its still valid given it does start with the basics.  But you might want to read the book 2 or 3 times, skipping the advanced stuff on the first read.  For those who have some basics already then its going to be an awesome way to cement your knowledge and take it to the next levels.  And for the ADF experts, you are still going to pick up some great ADF nuggets.  Advice: every ADF developer should have one!

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• Help understanding my hard drive / partitioning situation... Pictures Included! :)

  - by xopenex

  So I have installed windows 7, and two different distros of linux... I have read and tried to understand things like "spanned" "extended" "primary" "swap" "dev/dev2/" "GRUB" "Windows Boot Loader/Manager" etc.... I have a very very limited understanding of all of it! :) I am trying to figure out how to get all OS boot options on one Boot manager (I'm thinking it will be GRUB), because at this point when i turn on my computer, I basically get two booting options (excluding the memtest options etc)... One options is to boot one of my Linux Distros and the second option is to boot my Windows 7. When i go with the first option, Linux boots up... when i go with the second Windows 7 option, I get the "windows boot manager screen" and I can choose Windows 7 or my other installation of Linux (Ubuntu)... In addition, I did not have swap partition from my first installation of Linux, I created it during the installation of my second distro... This is a lot of info for me, but I'm guessing that you linux Gurus, pretty much understand what is going on! Hope my question makes sense.. i will try and simplify... Can i get all 3 OS's optioned to boot from one GRUB? Can i get both Linux distros to use one swap file (I have seen this possible in other threads, but because of how my disk is partitioned, i dont know if i can do this) I hope that i dont have to start all over installing one after the other. Ive got some pics that may help understand my hard drive situation! Thanks guys! :) EDIT... i had some pics, but im a new member.. so cant post them... :( here is a description of the pics... incase i can email them or post later. [grub][3] First Screen I come to after turning on computer... "Ubuntu with linux 3.2.6" (highlighted) fires up Linux perfectly... other choice at bottom of list "Windows 7 (loader) (on dev/sda1)... brings me to the next picture below.. windows boot manager [win boot mngr][6] both options here load the os selected [Disk Manager Windows][1] picture of my hard drive situation through windows disk manager utility [gparted][2] picture of my hard drive situation through "gparted" [mycomp][4] picture of my hard drive situation through "my computer" [paragon][5] one last pic of my hard drive situation through the eyes of "paragon"

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• Application workflow

  - by manseuk

  I am in the planning process for a new application, the application will be written in PHP (using the Symfony 2 framework) but I'm not sure how relevant that is. The application will be browser based, although there will eventually be API access for other systems to interact with the data stored within the application, again probably not relavent at this point. The application manages SIM cards for lots of different providers - each SIM card belongs to a single provider but a single customer might have many SIM cards across many providers. The application allows the user to perform actions against the SIM card - for example Activate it, Barr it, Check on its status etc Some of the providers provide an API for doing this - so a single access point with multiple methods eg activateSIM, getStatus, barrSIM etc. The method names differ for each provider and some providers offer methods for extra functions that others don't. Some providers don't have APIs but do offer these methods by sending emails with attachments - the attachments are normally a CSV file that contains the SIM reference and action required - the email is processed by the provider and replied to once the action has been complete. To give you an example - the front end of my application will provide a customer with a list of SIM cards they own and give them access to the actions that are provided by the provider of each specific SIM card - some methods may require extra data which will either be stored in the backend or collected from the user frontend. Once the user has selected their action and added any required data I will handle the process in the backend and provide either instant feedback, in the case of the providers with APIs, or start the process off by sending an email and waiting for its reply before processing it and updating the backend so that next time the user checks the SIM card its status is correct (ie updated by a backend process). My reason for creating this question is because I'm stuck !! I'm confused about how to approach the actual workflow logic. I was thinking about creating a Provider Interface with the most common methods getStatus, activateSIM and barrSIM and then implementing that interface for each provider. So class Provider1 implements Provider - Then use a Factory to create the required class depending on user selected SIM card and invoking the method selected. This would work fine if all providers offered the same methods but they don't - there are a subset which are common but some providers offer extra methods - how can I implement that flexibly ? How can I deal with the processes where the workflow is different - ie some methods require and API call and value returned and some require an email to be sent and the next stage of the process doesn't start until the email reply is recieved ... Please help ! (I hope this is a readable question and that this is the correct place to be asking) Update I guess what I'm trying to avoid is a big if or switch / case statement - some design pattern that gives me a flexible approach to implementing this kind of fluid workflow .. anyone ?

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• How to temporarily save the result of the query, to use in another?

  - by Truth

  I have this problem I think you may help me with. P.S. I'm not sure how to call this, so if anyone finds a more appropriate title, please do edit. Background I'm making this application for searching bus transit lines. Bus lines are a 3 digit number, and is unique and will never change. The requirement is to be able to search for lines from stop A to stop B. The user interface is already successful in hinting the user to only use valid stop names. The requirement is to be able to display if a route has a direct line, and if not, display a 2-line and even 3-line combination. Example: I need to get from point A to point D. The program should show: If there's a direct line A-D. If not, display alternative, 2 line combos, such as A-C, C-D. If there aren't any 2-line combos, search for 3-line combos: A-B, B-C, C-D. Of course, the app should display bus line numbers, as well as when to switch buses. What I have: My database is structured as follows (simplified, actual database includes locations and times and whatnot): +-----------+ | bus_stops | +----+------+ | id | name | +----+------+ +-------------------------------+ | lines_stops_relationship | +-------------+---------+-------+ | bus_line | stop_id | order | +-------------+---------+-------+ Where lines_stops_relationship describe a many-to-many relationship between the bus lines and the stops. Order, signifies the order in which stops appear in a single line. Not all lines go back and forth, and order has meaning (point A with order 2 comes after point B with order 1). The Problem We find out if a line can pass through the route easily enough. Just search for a single line which passes through both points in the correct order. How can I find if there's a 2/3 line combo? I was thinking to search for a line which matches the source stop, and one for the destination stop, and see if I can get a common stop between them, where the user can switch buses. How do I remember that stop? 3 line combo is even trickier, I find a line for the source, and a line for the destination, and then what? Search for a line which has 2 stops I guess, but again, How do I remember the stops? tl;dr How do I remember results from a query to be able to use it again? I'm hoping to achieve this in a single query (for each, a query for 1-line routes, a query for 2, and a query for 3-line combos). Note: I don't mind if someone suggests a completely different approach than what I have, I'm open to any solutions. Will award any assistance with a cookie and an upvote. Thanks in advance!

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• PMDB Block Size Choice

  - by Brian Diehl

  Choosing a block size for the P6 PMDB database is not a difficult task. In fact, taking the default of 8k is going to be just fine. Block size is one of those things that is always hotly debated. Everyone has their personal preference and can sight plenty of good reasons for their choice. To add to the confusion, Oracle supports multiple block sizes withing the same instance. So how to decide and what is the justification? Like most OLTP systems, Oracle Primavera P6 has a wide variety of data. A typical table's average row size may be less than 50 bytes or upwards of 500 bytes. There are also several tables with BLOB types but the LOB data tends not to be very large. It is likely that no single block size would be perfect for every table. So how to choose? My preference is for the 8k (8192 bytes) block size. It is a good compromise that is not too small for the wider rows, yet not to big for the thin rows. It is also important to remember that database blocks are the smallest unit of change and caching. I prefer to have more, individual "working units" in my database. For an instance with 4gb of buffer cache, an 8k block will provide 524,288 blocks of cache. The following SQL*Plus script returns the average, median, min, and max rows per block. column "AVG(CNT)" format 999.99 set verify off select avg(cnt), median(cnt), min(cnt), max(cnt), count(*) from ( select dbms_rowid.ROWID_RELATIVE_FNO(rowid) , dbms_rowid.ROWID_BLOCK_NUMBER(rowid) , count(*) cnt from &tab group by dbms_rowid.ROWID_RELATIVE_FNO(rowid) , dbms_rowid.ROWID_BLOCK_NUMBER(rowid) ) Running this for the TASK table, I get this result on a database with an 8k block size. Each activity, on average, has about 19 rows per block. Enter value for tab: task AVG(CNT) MEDIAN(CNT) MIN(CNT) MAX(CNT) COUNT(*) -------- ----------- ---------- ---------- ---------- 18.72 19 3 28 415917 I recommend an 8k block size for the P6 transactional database. All of our internal performance and scalability test are done with this block size. This does not mean that other block sizes will not work. Instead, like many other parameters, this is the safest choice.

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• Running MS Access Programs

  - by fredhappier

  I have an old program developed in MS Access and would like to convert it to Kexi somehow. The program on Windows is launched with Access. Is there any way that Kexi can launch this program? I know my way around Ubuntu and the terminal, but not well versed on databases. Once you make something in Kexi how do you "run" it or "view" what you've made? So far I am able to import the MDB file into Kexi and see all of the database data, but that is as far I have gone. The program was made by a relative years ago for my dad. I myself am an Ubuntu only user for 6+ years now and have no intentions to touch Windows and am looking for a linux solution. My dad is also an Ubuntu user, hence why Im looking for a solution. If Kexi cannot launch and run an MDB file, what else can I try? Anything browser based? Any tips or direction would be extremely helpful. I spoke to my brother who originally made the program. I told him about Kexi and here is what he said. Does any of this make sense? Thanks. This is how I would try to get them to work: Stand alone setup - after import, look for an option where you designate which form object you want to open upon startup. It might be in the tools tab in the picture below. After you save that change, it re-start it and it should work. Front end/back end setup - Do what I suggested for the stand alone setup to the "front-end" MDB file. After you do that, put the other file (table MDB file) where you want it to reside on the network. Now, open back up the "front end" file and look for an option that will allow you to "connect" to those tables in the other file. It looks like it could be in the "External data" tab in the picture below. For this setup, you may need to do these two tasks in the reverse order I just mentioned. Thanks! Fred

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• Series On Embedded Development (Part 2) - Build-Time Optionality

  - by user12612705

  In this entry on embedded development, I'm going to discuss build-time optionality (BTO). BTO is the ability to subset your software at build-time so you only use what is needed. BTO typically pertains more to software providers rather then developers of final products. For example, software providers ship source products, frameworks or platforms which are used by developers to build other products. If you provide a source product, you probably don't have to do anything to support BTO as the developers using your source will only use the source they need to build their product. If you provide a framework, then there are some things you can do to support BTO. Say you provide a Java framework which supports audio and video. If you provide this framework in a single JAR, then developers who only want audio are forced to ship their product with the video portion of your framework even though they aren't using it. In this case, support providing the framework in separate JARs...break the framework into an audio JAR and a video JAR and let the users of your framework decide which JARs to include in their product. Sometimes this is as simple as packaging, but if, for example, the video functionality is dependent on the audio functionality, it may require coding work to cleanly separate the two. BTO can also work at install-time, and this is sometimes overlooked. Let's say your building a phone application which can use Near Field Communications (NFC) if it's available on the phone, but it doesn't require NFC to work. Typically you'd write one app for all phones (saving you time)...both those that have NFC and those that don't, and just use NFC if it's there. However, for better efficiency, you can detect at install-time if the phone supports NFC and not install the NFC portion of your app if the phone doesn't support NFC. This requires that you write the app so it can run without the optional NFC code and that you write your install app so it can detect NFC and do the right thing at install-time. Supporting install-time optionality will save persistent footprint on the phone, something your customers will appreciate, your app "neighbors" will appreciate, and that you'll appreciate when they save static footprint for you. In the next article, I'll talk about runtime optionality.

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• laptop will not boot after attempting upgrade to 13.10

  - by naerwenya

  I wanted to update my OS to the new 14.04 LTS. I was running 12.04 LTS before and followed the advice that upgrades should be done in steps. I first upgraded to 12.10, which seemed to work fine, and later to 13.10. This was all done through the Software Manager. After the last upgrade, I am no longer able to boot up my computer. The GNU GRUB menu opens up, but after selecting Ubuntu, it just stalls with a blank purple screen. If I select one of the other kernels, it also stalls after "Loading initial ramdisk...". I can't get into the Recovery Menu, either. I'm still rather new to Linux and may have possibly made the situation worse. Unfortunately, nothing has worked yet. I tried reinstalling from a flash drive and on my first attempt, the wizard recognised a previous installation. Unfortunately, the wizard also didn't like how my partitions were set up (I didn't change anything) and gave an error before closing. Unfortunately, I didn't write the error down, but it was about the boot partition. On the next attempt and ever since, the installation wizard has stated that "This computer currently has no detected operating systems." This is strange, because I could see the disk and even access my files when booting up from the USB. At this point, I decided to back up my important files using dropbox. Before losing all my files, I wanted to try the Boot-Repair tool, which also produced no results, and the files are no longer visible when booting from USB. The link to the Boot-Repair log is at http://paste.ubuntu.com/7457249/. If I then proceed through to the "Something else" installation option, I can see that the partitions still exist. This is what they look like: /dev/sda free space (size indicated 1MB) /dev/sda1 efi (33MB of 98 MB used) /dev/sda2 efi (352634MB of 746330MB used) /dev/sda3 swap (3725MB, none used) free space (0MB) Is there any way I might be able to get my computer to work and preserve my files as well?

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• Is it good practice to keep 2 related tables (using auto_increment PK) to have the same Max of auto_increment ID when table1 got modified?

  - by Tum

  This question is about good design practice in programming. Let see this example, we have 2 interrelated tables: Table1 textID - text 1 - love.. 2 - men... ... Table2 rID - textID 1 - 1 2 - 2 ... Note: In Table1: textID is auto_increment primary key In Table2: rID is auto_increment primary key & textID is foreign key The relationship is that 1 rID will have 1 and only 1 textID but 1 textID can have a few rID. So, when table1 got modification then table2 should be updated accordingly. Ok, here is a fictitious example. You build a very complicated system. When you modify 1 record in table1, you need to keep track of the related record in table2. To keep track, you can do like this: Option 1: When you modify a record in table1, you will try to modify a related record in table 2. This could be quite hard in term of programming expecially for a very very complicated system. Option 2: instead of modifying a related record in table2, you decided to delete old record in table 2 & insert new one. This is easier for you to program. For example, suppose you are using option2, then when you modify record 1,2,3,....,100 in table1, the table2 will look like this: Table2 rID - textID 101 - 1 102 - 2 ... 200 - 100 This means the Max of auto_increment IDs in table1 is still the same (100) but the Max of auto_increment IDs in table2 already reached 200. what if the user modify many times? if they do then the table2 may run out of records? we can use BigInt but that make the app run slower? Note: If you spend time to program to modify records in table2 when table1 got modified then it will be very hard & thus it will be error prone. But if you just clear the old record & insert new records into table2 then it is much easy to program & thus your program is simpler & less error prone. So, is it good practice to keep 2 related tables (using auto_increment PK) to have the same Max of auto_increment ID when table1 got modified?

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