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  • Should I always release self for failed init methods?

    - by leo
    Should I always release self when there is a failure inside init, or should I only do so if I have initialized instance variables first? To put it another way, is this pattern valid? Is there a time when I shouldn't release self inside an init method, or should I assume that if the control flow enters init, self has at least a retain count of 1? - (id)init { if ((self = [super init]) == nil) { [self release]; return nil; } //do some init stuff if (somethingFailed) { [self release]; return nil; } return self; }

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  • Efficient bitshifting an array of int?

    - by nn
    Hi, To be on the same page, let's assume sizeof(int)=4 and sizeof(long)=8. Given an array of integers, what would be an efficient method to bitshift the array to either the left or right? I am contemplating an auxiliary variable such as a long, that will compute the bitshift for the first pair of elements (index 0 and 1) and set the first element (0). Continuing in this fashion the bitshift for elements (index 1 and 2) will be computer, and then index 1 will be set. I think this is actually a fairly efficient method, but there are drawbacks. I cannot bitshift greater than 32 bits. I think using multiple auxiliary variables would work, but I'm envisioning recursion somewhere along the line.

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  • C++ function-pointer and inheritance

    - by pingvinus
    In parent class I have function, that operates under an array of functions, declared in child-class, number of functions for every child-class may vary. But since every function uses some object-variables, I can't declare them as static. I've try to do something like this: class A { public: typedef int (A::*func)(); func * fs; void f() { /*call functions from this->fs*/ } }; class B : public A { public: int smth; B(int smth) { this->smth = smth; this->fs = new func[1]; fs[0] = &B::f; } int f() { return smth + 1; } }; But, obviously it doesn't work. Any suggestions?

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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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  • How does a Java Arraylist contains() method evaluate objects?

    - by mvid
    Say i create one object and add it to my ArrayList. If I then create another object with exactly the same constructor input, will the contain() method evaluate the two objects to be the same? Assume the constructor doesn't do anything funny with the input, and the variables stored in both objects are identical. ArrayList<Thing> basket = new ArrayList<Thing>(); Thing thing = new Thing(100); basket.add(thing); Thing another = new Thing(100); basket.contains(another); // true or false?

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  • Do I need to install Glassfish?

    - by Ayusman
    Hi, I am new to glassfish server. i have a question on glassfish usage: can I just use glassfish like a tomcat server without needing an installation? where in, I just take a folder containing glassfish folders, jars etc... dump it in a folder location setup a few environment variables and it runs.. just like tomcat? is it possible with glassfish? also does glassfish installation does any other background things like creating registry entries etc other than creating the glassfish folder structure? TIA Ayusman

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  • Creating a virtual, data-driven section of a Wordpress-powered site

    - by lgomez
    Hello all, I want to create a plugin for wordpress to automatically serve pages containing data pulled from a provider's API. The API returns one or more records containing data for that record and I simply want to have the plugin intercept the request, call the API with parameters pulled from the request URI and display the data using a template that I can either let them upload to the server or let them copy and paste into the plugins admin settings. For example, I may want one of my wordpress installations to show products pulled from such an API under the url "example.com/products". The plugin would catch that request, extract the variables from the URL, call the API and render the template with the returned results. I'd like to avoid requiring editing the .htaccess file like some caching plugins do. Some of the admins of these pages won't know how to do that or simply won't have access to the .htaccess file. Thanks!

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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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  • Integrate variable data with div tag in asp.net

    - by Srikanth Mattihalli
    Hi all, I have this code: I need to replace 800px and 300px from database value; I tried both of the below. But still i am not getting the answer. Method 1: <div id="container" style="width:'<% Response.Write(width);%>'px; height:'<% Response.Write(height);%>'px; margin: 0 auto;overflow:hidden;"></div> Method 2: <div id="container" style="width:'<%# Eval("width");%>'px; height: <%# Eval("height");%>'px; margin: 0 auto;overflow:hidden;"></div> The value of height and width variables are defined in page_load() function int height=300; int width= 800; This is not affecting the resulting web page. Can anyone help me on this.

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  • undefined reference to static member variable

    - by Max
    Hi. I have this class that has a static member. it is also a base class for several other classes in my program. Here's its header file: #ifndef YARL_OBJECT_HPP #define YARL_OBJECT_HPP namespace yarlObject { class YarlObject { // Member Variables private: static int nextID; // keeps track of the next ID number to be used int ID; // the identifier for a specific object // Member Functions public: YarlObject(): ID(++nextID) {} virtual ~YarlObject() {} int getID() const {return ID;} }; } #endif and here's its implementation file. #include "YarlObject.hpp" namespace yarlObject { int YarlObject::nextID = 0; } I'm using g++, and it returns three undefined reference to 'yarlObject::YarlObject::nextID linker errors. If I change the ++nextID phrase in the constructor to just nextID, then I only get one error, and if I change it to 1, then it links correctly. I imagine it's something simple, but what's going on?

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  • How to structure web application with part of it being secured (SSL)

    - by spirytus
    What is the common pattern to structure web application where part of it has to be secured. So lets say I have page_a and page_b which do not need to be secured, although should display login information (login fields or login details once user logged in). This web app. also would have secured pages (admin, checkout or similar) secure_page_c and secure_page_d. My questions are: What is the common folder structure for such assuming I code in php with no frameworks? Also how shall I deal with session variables in case user navigates lets say from secure_page_b to non secure page_a or vice versa? What else might be a problem and should be considered when coding that kind of app in php? Thank you all for any suggestions

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  • Code Golf: Ghost Leg

    - by Anax
    The challenge The shortest code by character count that will output the numeric solution, given a number and a valid string pattern, using the Ghost Leg method. Examples Input: 3, "| | | | | | | | |-| |=| | | | | |-| | |-| |=| | | |-| |-| | |-|" Output: 2 Input: 2, "| | |=| | |-| |-| | | |-| | |" Output: 1 Clarifications Do not bother with input. Consider the values as given somewhere else. Both input values are valid: the column number corresponds to an existing column and the pattern only contains the symbols |, -, = (and [space], [LF]). Also, two adjacent columns cannot both contain dashes (in the same line). The dimensions of the pattern are unknown (min 1x1). Clarifications #2 There are two invalid patterns: |-|-| and |=|=| which create ambiguity. The given input string will never contain those. The input variables are the same for all; a numeric value and a string representing the pattern. Entrants must produce a function. Test case Given pattern: "|-| |=|-|=|LF| |-| | |-|LF|=| |-| | |LF| | |-|=|-|" |-| |=|-|=| | |-| | |-| |=| |-| | | | | |-|=|-| Given value : Expected result 1 : 6 2 : 1 3 : 3 4 : 6 5 : 5 6 : 2

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  • Is there an easy way in Python to wait until certain condition is true?

    - by Checkers
    I need to wait in a script until a certain number of conditions become true? I know I can roll my own eventing using condition variables and friends, but I don't want to go through all the trouble of implementing it, since some object property changes come from external thread in a wrapped C++ library (Boost.Python), so I can't just hijack __setattr__ in a class and put a condition variable there, which leaves me with either trying to create and signal a Python condition variable from C++, or wrap a native one and wait on it in Python, both of which sound fiddly, needlessly complicated and boring. Is there an easier way to do it, barring continuous polling of the condition? Ideally it would be along the lines of res = wait_until(lambda: some_predicate, timeout) if (not res): print 'timed out'

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  • how does "recent history" work on sites for php? (PHP)

    - by ggfan
    I'm not sure if there is an explanation on SO for beginners, but if so, could you provide the links. I am interested in creating a "recent viewed" function that shows what links they clicked on before. I'm not sure if this is the 'correct' way to do it, but this is what I have so far... user clicks on a link(say ad.php?posting_id=12). if the user doesn't click on the link, no cookie or session is stored for the link if the user clicks on the link, it sets a cookie for $_cookie['ad.php?posting_id=22'] Each time the user clicks, more cookies are set In the recent viewed function, it gets all the $_cookie variables and displays them. if the user wants to clear the history, just destroy all the cookies I'm not sure if this is the way to do it, but is the viable? If not, what are the steps to create a "recent viewed" function

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  • BASH Expression to replace beginning and ending of a string in one operation?

    - by swestrup
    Here's a simple problem that's been bugging me for some time. I often find I have a number of input files in some directory, and I want to construct output file names by replacing beginning and ending portions. For example, given this: source/foo.c source/bar.c source/foo_bar.c I often end up writing BASH expressions like: for f in source/*.c; do a="obj/${f##*/}" b="${a%.*}.obj" process "$f" "$b" done to generate the commands process "source/foo.c" "obj/foo.obj" process "source/bar.c "obj/bar.obj" process "source/foo_bar.c "obj/foo_bar.obj" The above works, but its a lot wordier than I like, and I would prefer to avoid the temporary variables. Ideally there would be some command that could replace the beginning and ends of a string in one shot, so that I could just write something like: for f in source/*.c; do process "$f" "obj/${f##*/%.*}.obj"; done Of course, the above doesn't work. Does anyone know something that will? I'm just trying to save myself some typing here.

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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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  • Is it ok to store large objects (java component for example) in an Application variable?

    - by DustMason
    I am developing an app right now which creates and stores a connection to a local XMPP server in the Application scope. The connection methods are stored in a cfc that makes sure the Application.XMPPConnection is connected and authorized each time it is used, and makes use of the connection to send live events to users. As far as I can tell, this is working fine. BUT it hasn't been tested under any kind of stress. My question is: Will this set up cause problems later on? I only ask because I can't find evidence of other people using Application variables in this way. If I weren't using railo I would be using CF's event gateway instead to accomplish the same task.

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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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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