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  • How to drop a primary key using ActiveRecord migrations

    - by knoopx
    Due to a mistake I forgot to add :id => false to a has_many :trough table creation migration. Now I reverted the association back to a has_and_belongs_to_many and ActiveRecord throws an exception complaining about the presence of the primary key. I couldn't find any reference on the ActiveRecord documentation so, do you know if there is any standard, clean way of doing it?

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  • wildcards to use in codeigniter routing?

    - by ajsie
    in codeigniter you can use wildcard to reroute. i never heard the word wildcards before. is this a set of rules you can use like regexp? cause in codeigniter documentation they just gave some examples eg. $route['product/(:num)'] = "catalog/product_lookup_by_id/$1"; is there a list/reference with all the available wildcard expressions you can use?

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  • Understanding Java Wait and Notify methods

    - by Maddy
    Hello all: I have a following program: import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class SimpleWaitNotify implements Runnable { final static Object obj = new Object(); static boolean value = true; public synchronized void flag() { System.out.println("Before Wait"); try { obj.wait(); } catch (InterruptedException e) { System.out.println("Thread interrupted"); } System.out.println("After Being Notified"); } public synchronized void unflag() { System.out.println("Before Notify All"); obj.notifyAll(); System.out.println("After Notify All Method Call"); } public void run() { if (value) { flag(); } else { unflag(); } } public static void main(String[] args) throws InterruptedException { ExecutorService pool = Executors.newFixedThreadPool(4); SimpleWaitNotify sWait = new SimpleWaitNotify(); pool.execute(sWait); SimpleWaitNotify.value = false; SimpleWaitNotify sNotify = new SimpleWaitNotify(); pool.execute(sNotify); pool.shutdown(); } } When I wait on obj, I get the following exception Exception in thread "pool-1-thread-1" java.lang.IllegalMonitorStateException: current thread not owner for each of the two threads. But if I use SimpleWaitNotify's monitor then the program execution is suspended. In other words, I think it suspends current execution thread and in turn the executor. Any help towards understanding what's going on would be duly appreciated. This is an area1 where the theory and javadoc seem straightforward, and since there aren't many examples, conceptually left a big gap in me.

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  • Rails migration: t.references with alternative name?

    - by marienbad
    So I have a create_table like this for Courses at a School: create_table :courses do |t| t.string :name t.references :course t.timestamps end but I want it to reference TWO other courses like: has_many :transferrable_as #a Course has_many :same_as #another Course can I say t.references :transferrable_as, :as= :course ?

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  • Pointers in C# to make int array?

    - by Joshua
    The following C++ program compiles and runs as expected: #include <stdio.h> int main(int argc, char* argv[]) { int* test = new int[10]; for (int i = 0; i < 10; i++) test[i] = i * 10; printf("%d \n", test[5]); // 50 printf("%d \n", 5[test]); // 50 return getchar(); } The closest C# simple example I could make for this question is: using System; class Program { unsafe static int Main(string[] args) { // error CS0029: Cannot implicitly convert type 'int[]' to 'int*' int* test = new int[10]; for (int i = 0; i < 10; i++) test[i] = i * 10; Console.WriteLine(test[5]); // 50 Console.WriteLine(5[test]); // Error return (int)Console.ReadKey().Key; } } So how do I make the pointer?

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  • Selecting a column that is also a keyword in MySQL

    - by randall123
    For some reason, the developers at a new company I'm working for decided to name their columns "ignore" and "exists". Now when I run MySQL queries with those words in the where clause, I get a syntax error; however, I can't seem to figure out how to reference those columns without running into an error. I tried setting them as strings, but that doesn't make any sense. Help? Also, is there a term for this kind of mismatch?

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  • How should I start to play with 3D

    - by MarceloRamires
    I'm a developer for just about 6 months now, and since I enjoy programming I make a couple of little programs. I've startedmaking encripters, calculators, tools, stuff to play with DropBox (hehe), stuff that play with bitmaps, drawing graphics, and even a program to update the MSN display image according to the artwork of the music you're listening yo on iTunes. Now I kind of ran off ideas of programs to deal with information, and I've had an idea: play around with 3d! so I've read a little about it and figured I'd have to have good notions on position and math on point spacial position (which I do, from my 3d modelling experience), but I don't know how to use API's for it, so I've 'simulated' simple 3d with a simple program I've made (it's just a spinning cube, please, first one to open it, comment here stating that it's safe, i've got no reason to harm anyone's pc.) One of my other hobbies is 3d modelling (completly amateur) and I'd like to mix these hobbies together! Here are some questions: 1) What would be a nice 3d development tool for a .NET programmer like me? 2) Is there a way of using 3d models made in 3DS Max ? (I intend on modelling characters) 3) What knowledges should I have in order to render it, and move it areound ? 4) Which API should I use ? NOTE: Not a dupe, I'm asking for directions specific for .NET development possibly using 3ds MAX, and there's no question about it!

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  • C# Simple Event Handler for Setting Alarm

    - by yeeen
    Why does the following line "alarm.AlarmEvent += new AlarmEventHandler(alarm_Sound);" gives me "An object reference is required for the non-static field, method, or property 'AlarmClock.Alarm.alarm_Sound(object, System.EventArgs)'" public static void Main(string[] args) { Alarm alarm = new Alarm(new DateTime(2010, 4, 7, 23, 2, 0)); alarm.Set(); alarm.AlarmEvent += new AlarmEventHandler(alarm_Sound); } Full source code here: Program.cs AlarmEventArgs

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  • Gratuitous use of System.Runtime.Serialization attributes?

    - by rasx
    Is there any cost/drawback (apart from typing too much) to adorning a class with System.Runtime.Serialization attributes (like [DataContract]) such that it can be used locally as a direct reference to a desktop Client project or as a type for a WCF service? The goal here is to write a data-tier class that can be used in both rich client (WPF) and Web scenarios. My data classes will be in a project that is separate from Client and WCF (*.svc code-behind) code. Is this a valid attempt to reuse code?

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  • Gnuplot python with 2 list

    - by devil night
    I've a python script that gives me 2 lists and another who is the reference(the time). How can I create a graphic with the representation of my first list by the time. And same question for the second list. I need them on the same graphic. list1 [12, 15, 17, 19] list2 [34, 78, 54, 67] list3 [10, 20, 30, 40] (time in minutes) How can I create a graphic in png format with these lists? Thanks

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  • Static library not included in resulting LLVM executable

    - by Matthew Glubb
    Hi, I am trying to compile a c program using LLVM and I am having trouble getting some static libraries included. I have successfully compiled those static libraries using LLVM and, for example, libogg.a is present, as is ogg.l.bc. However, when I try to build the final program, it does not include the static ogg library. I've tried various compiler options with the most notable being: gcc oggvorbis.c -O3 -Wall -I$OV_DIR/include -l$OV_DIR/lib/libogg.a -l$OV_DIR/lib/libvorbis.a -o test.exe This results in the following output (directories shortened for brevity): $OV_DIR/include/vorbis/vorbisfile.h:75: warning: ‘OV_CALLBACKS_DEFAULT’ defined but not used $OV_DIR/include/vorbis/vorbisfile.h:82: warning: ‘OV_CALLBACKS_NOCLOSE’ defined but not used $OV_DIR/include/vorbis/vorbisfile.h:89: warning: ‘OV_CALLBACKS_STREAMONLY’ defined but not used $OV_DIR/include/vorbis/vorbisfile.h:96: warning: ‘OV_CALLBACKS_STREAMONLY_NOCLOSE’ defined but not used llvm-ld: warning: Cannot find library '$OV_DIR/lib/ogg.l.bc' llvm-ld: warning: Cannot find library '$OV_DIR/lib/vorbis.l.bc' WARNING: While resolving call to function 'main' arguments were dropped! I find this perplexing because $OV_DIR/lib/ogg.l.bc DOES exit, as does vorbis.l.bc and they are both readable (as are their containing directories) by everyone. Does anyone have any idea with what I am doing wrong? Thanks, Matt

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  • Directly call distutils' or setuptools' setup() function with command name/options, without parsing

    - by Ryan B. Lynch
    I'd like to call Python's distutils' or setuptools' setup() function in a slightly unconventional way, but I'm not sure whether distutils is meant for this kind of usage. As an example, let's say I currently have a 'setup.py' file, which looks like this (lifted verbatim from the distutils docs--the setuptools usage is almost identical): from distutils.core import setup setup(name='Distutils', version='1.0', description='Python Distribution Utilities', author='Greg Ward', author_email='[email protected]', url='http://www.python.org/sigs/distutils-sig/', packages=['distutils', 'distutils.command'], ) Normally, to build just the .spec file for an RPM of this module, I could run python setup.py bdist_rpm --spec-only, which parses the command line and calls the 'bdist_rpm' code to handle the RPM-specific stuff. The .spec file ends up in './dist'. How can I change my setup() invocation so that it runs the 'bdist_rpm' command with the '--spec-only' option, WITHOUT parsing command-line parameters? Can I pass the command name and options as parameters to setup()? Or can I manually construct a command line, and pass that as a parameter, instead? NOTE: I already know that I could call the script in a separate process, with an actual command line, using os.system() or the subprocess module or something similar. I'm trying to avoid using any kind of external command invocations. I'm looking specifically for a solution that runs setup() in the current interpreter. For background, I'm converting some release-management shell scripts into a single Python program. One of the tasks is running 'setup.py' to generate a .spec file for further pre-release testing. Running 'setup.py' as an external command, with its own command line options, seems like an awkward method, and it complicates the rest of the program. I feel like there may be a more Pythonic way.

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  • Different Linux message queues have the same id?

    - by Halo
    I open a mesage queue in a .c file, and upon success it says the message queue id is 3. While that program is still running, in another terminal I start another program (of another .c file), that creates a new message queue with a different mqd_t. But its id also appears as 3. Is this a problem? server file goes like this: void server(char* req_mq) { struct mq_attr attr; mqd_t mqdes; struct request* msgptr; int n; char *bufptr; int buflen; pid_t apid; //attr.mq_maxmsg = 300; //attr.mq_msgsize = 1024; mqdes = mq_open(req_mq, O_RDWR | O_CREAT, 0666, NULL); if (mqdes == -1) { perror("can not create msg queue\n"); exit(1); } printf("server mq created, mq id = %d\n", (int) mqdes); and the client goes like: void client(char* req_mq, int min, int max, char* dir_path_name, char* outfile) { pid_t pid; /* get the process id */ if ((pid = getpid()) < 0) { perror("unable to get client pid"); } mqd_t mqd, dq; char pfx[50] = DQ_PRFX; char suffix[50]; // sprintf(suffix, "%d", pid); strcat(pfx, suffix); dq = mq_open(pfx, O_RDWR | O_CREAT, 0666, NULL); if (dq == -1) { perror("can not open data queue\n"); exit(1); } printf("data queue created, mq id = %d\n", (int) dq); mqd = mq_open(req_mq, O_RDWR); if (mqd == -1) { perror("can not open msg queue\n"); exit(1); } mqdes and dq seem to share the same id 3.

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  • What kinds of problems are most likely to occur? (question rewritten)

    - by ChrisC
    If I wrote 1) a C# SQL db app (a simple program consisting of a gui over some forms with logic for interfacing with the sql db) 2) for home use, that doesn't do any network communication 3) that uses a simple, reliable, and appropriate sql db 4) whose gui is properly separated from the logic 5) that has complete and dependable input data validation 6) that has been completely tested so that 100% of logic bugs were eliminated ... and then if the program was installed and run by random users on their random Windows computers Q1) What types of technical (non-procedural) problems and support situations are most likely to occur, and how likely are they? Q2) Are there more/other things I could do in the first place to prevent those problems and also minimize the amount of user support required? I know some answers will apply to my specific platforms (C#, SQL, Windows, etc) and some won't. Please be as specific as is possible. Mitch Wheat gave me some very valuable advice below, but I'm now offering the bounty because I am hoping to get a better picture of the kinds of things that I'm most reasonably likely to encounter. Thanks.

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  • How can I create an executable to run on a certain processor architecture (instead of certain OS)?

    - by CrazyJugglerDrummer
    So I take my C++ program in Visual studio, compile, and it'll spit out a nice little EXE file. But EXEs will only run on windows, and I hear a lot about how C/C++ compiles into assembly language, which is runs directly on a processor. The EXE runs with the help of windows, or I could have a program that makes an executable that runs on a mac. But aren't I compiling C++ code into assembly language, which is processor specific? My Insights: I'm guessing I'm probably not. I know there's an Intel C++ compiler, so would it make processor-specific assembly code? EXEs run on windows, so they advantage of tons of things already set up, from graphics packages to the massive .NET framework. A processor-specific executable would be literally starting from scratch, with just the instruction set of the processor. Would this executable be a file-type? We could be running windows and open it, but then would control switch to processor only? I assume this executable would be something like an operating system, in that it would have to be run before anything else was booted up, and have only the processor instruction set to "use".

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  • How to become sharepoint developer from ASP.NET/Silverlight developer?

    - by funwithcoding
    Hello friends, I heard from my peers that knowledge of sharepoint is going to be good for career. We do not use sharepoint at our office. So dont know how to get started. These are my sharepoint newbie questions Is learning sharepoint worth the effort? Where are the resources to learn sharepoint? Is there any reference project I should considering aiming to develop? Appreciate your inputs.

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  • How do i add a string template to views in .net mvc?

    - by Lina
    Hi, I have a newbie question,, how do i add a string template to the views folder in a .net mvc project? i have added a reference to StringTemplate.dll and antlr.runtime.dll but seems that is not enough. i.e. when i right-click on views and choose Add New Item i can't find a file with .st extension in the list that i get... how do i achieve that? Thanks a million in advance

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  • mysql concat all field table

    - by hafizan
    Is there a way we can concat all field in the table(1 sql statement)(automatic) ? The reason was before user updated or delete a record,the record will push to another table for future reference.

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  • Are Fortran control characters (carriage control) still implemented in compilers?

    - by CmdrGuard
    In the book Fortran 95/2003 for Scientists and Engineers, there is much talk given to the importance of recognizing that the first column in a format statement is reserved for control characters. I've also seen control characters referred to as carriage control on the internet. To avoid confusion, by control characters, I refer to the characters "1, a blank (i.e. \s), 0, and +" as having an effect on the vertical spacing of output when placed in the first column (character) of a FORMAT statement. Also, see this text-only web page written entirely in fixed-width typeface : Fortran carriage-control (because nothing screams accuracy and antiquity better than prose in monospaced font). I found this page and others like it to be not quite clear. According to Fortran 95/2003 for Scientists and Engineers, failure to recall that the first column is reserved for carriage control can lead to horrible unintended output. Paraphrasing Dave Barry, type the wrong character, and nuclear missiles get fired at Norway. However, when I attempt to adhere to this stern warning, I find that gfortran has no idea what I'm talking about. Allow me to illustrate my point with some example code. I am trying to print out the number Pi: PROGRAM test_format IMPLICIT NONE REAL :: PI = 2 * ACOS(0.0) WRITE (*, 100) PI WRITE (*, 200) PI WRITE (*, 300) PI 100 FORMAT ('1', "New page: ", F11.9) 200 FORMAT (' ', "Single Space: ", F11.9) 300 FORMAT ('0', "Double Space: ", F11.9) END PROGRAM test_format This is the output: 1New page: 3.141592741 Single Space: 3.141592741 0Double Space: 3.141592741 The "1" and "0" are not typos. It appears that gfortran is completely ignoring the control character column. My question, then, is this: Are control characters still implemented in standards compliant compilers or is gfortran simply not standards compliant? For clarity, here is the output of my gfortran -v Using built-in specs. Target: powerpc-apple-darwin9 Configured with: ../gcc-4.4.0/configure --prefix=/sw --prefix=/sw/lib/gcc4.4 --mandir=/sw/share/man --infodir=/sw/share/info --enable-languages=c,c++,fortran,objc,java --with-gmp=/sw --with-libiconv-prefix=/sw --with-ppl=/sw --with-cloog=/sw --with-system-zlib --x-includes=/usr/X11R6/include --x-libraries=/usr/X11R6/lib --disable-libjava-multilib --build=powerpc-apple-darwin9 --host=powerpc-apple-darwin9 --target=powerpc-apple-darwin9 Thread model: posix gcc version 4.4.0 (GCC)

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  • How would I set up this enum to return the image I want?

    - by Justen
    I'm trying to set up this enum so that it has the ability to return the correct image, though I'm struggling with a way to incorporate the context since it is in a separate class. public enum CubeType { GREEN { public Drawable getImage() { return Context.getResources().getDrawable( R.drawable.cube_green ); } }; abstract public Drawable getImage(); } The error I'm getting is: Cannot make a static reference to the non-static method getResources() from the type Context

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  • Running commands over ssh with Java

    - by Ichorus
    Scenerio: I'd like to run commands on remote machines from a Java program over ssh (I am using OpenSSH on my development machine). I'd also like to make the ssh connection by passing the password rather than setting up keys as I would with 'expect'. Problem: When trying to do the 'expect' like password login the Process that is created with ProcessBuilder cannot seem to see the password prompt. When running regular non-ssh commands (e.g 'ls') I can get the streams and interact with them just fine. I am combining standard error and standard out into one stream with redirectErrorStream(true); so I am not missing it in standard error...When I run ssh with the '-v' option, I see all of the logging in the stream but I do not see the prompt. This is my first time trying to use ProcessBuilder for something like this. I know it would be easier to use Python, Perl or good ol' expect but my boss wants to utilize what we are trying to get back (remote log files and running scripts) within an existing Java program so I am kind of stuck. Thanks in advance for the help!

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  • i386 assembly question: why do I need to meddle with the stack pointer?

    - by zneak
    Hello everyone, I decided it would be fun to learn x86 assembly during the summer break. So I started with a very simple hello world program, borrowing on free examples gcc -S could give me. I ended up with this: HELLO: .ascii "Hello, world!\12\0" .text .globl _main _main: pushl %ebp # 1. puts the base stack address on the stack movl %esp, %ebp # 2. puts the base stack address in the stack address register subl $20, %esp # 3. ??? pushl $HELLO # 4. push HELLO's address on the stack call _puts # 5. call puts xorl %eax, %eax # 6. zero %eax, probably not necessary since we didn't do anything with it leave # 7. clean up ret # 8. return # PROFIT! It compiles and even works! And I think I understand most of it. Though, magic happens at step 3. Would I remove this line, my program would die between the call to puts and the xor from a misaligned stack error. And would I change $20 to another value, it'd crash too. So I came to the conclusion that this value is very important. Problem is, I don't know what it does and why it's needed. Can anyone explain me? (I'm on Mac OS, would it ever matter.)

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  • Programmatically add IP(s) or domain(s) to Relay Restrictions in SMTP Virtual Server on IIS 6

    - by RJ
    I have been given a task to create an admin page to programmatically add IPs or domains to a SMTP Relay Restrictions using C#. I spent some time researching this since yesterday and finally traced this down to a few posts on several website that use the System.DirectoryServices.DirectoryEntr class. Using the examples I found, I can add or deny IPs or domains under Connection control but not Relay Restrictions. What would be the commands in C# to add IPs to the Relay Restrictions? Below is a pic of the GUI in IIS for reference.-

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  • Is Minus Zero some sort of JavaScript performance trick?

    - by James Wiseman
    Looking in the jQuery core I found the folloiwng code convention: nth: function(elem, i, match){ return match[3] - 0 === i; }, And I was really curious about the snippet match[3] - 0 Hunting around for '-0' on google isn't too productive, and a search for 'minus zero' brings back a reference to a Bob Dylan song. So, can anyone tell me. Is this some sort of performance trick, or is there a reason for doing this rather than a parseInt or parseFloat? Thanks

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