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  • Doubt about constructor in JAVA

    - by Harry Joy
    I have few doubts regarding constructor in java Can a constructor be private? If yes then in which condition? Constructor is a method or not? If constructor does not return anything then why we are getting a new Object every time we call it. Whats the default access modifier of a constructor if we did not specify. Thanks & Regards Edit---------- Answer for 1 & 3 are very clear. But still doubt about 2&4 as i'm getting different answers for them.

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  • How do I secure a folder used to let users upload files?

    - by Eduardo Molteni
    I have a folder in my web server used for the users to upload photos using an ASP page. Is it safe enough to give IUSR write permissions to the folder? Must I secure something else? I am afraid of hackers bypassing the ASP page and uploading content directly to the folder. I'm using ASP classic and IIS6 on Windows 2003 Server. The upload is through HTTP, not FTP. Edit: Changing the question for clarity and changing my answers as comments.

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  • Performance of: if (OBJECT_INSTANCE is TYPE)

    - by Axonn
    I am working both in C# and ActionScript 3. Both language are type-aware, so you can do verifications such as: if (some_object_instance is SomeClassName_ThatIs_SomeType) I'm doing these kind of verifications in a few places. Might be a dumb question, but I will ask it anyway, and I want answers from both camps, C# and ActionScript: What goes on behind the scenes? Is it Reflection? If is, isn't this a long verification which might degrade performance if done in thousands of loops? And by "degrade performance" I mean, is it more intensive than say if (Math.sqrt(8) > Math.sin(10))

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  • Copy a function in memory and execute it

    - by Elinghton
    Hi everybody, I would like to know how in C in can copy the content of a function into memroy and the execute it? I'm trying to do something like this: typedef void(*FUN)(int *); char * myNewFunc; char *allocExecutablePages (int pages) { template = (char *) valloc (getpagesize () * pages); if (mprotect (template, getpagesize (), PROT_READ|PROT_EXEC|PROT_WRITE) == -1) { perror ("mprotect"); } } void f1 (int *v) { *v = 10; } // allocate enough spcae but how much ?? myNewFunc = allocExecutablePages(...) /* Copy f1 somewere else * (how? assume that i know the size of f1 having done a (nm -S foo.o)) */ ((FUN)template)(&val); printf("%i",val); Thanks for your answers

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  • API For Flex Apps To Interact

    - by dimo414
    I have a large flex application (the app) running on one server, and many small flex applications (widgets) running on another server, which are to be included in the app so that visually the user see's one continuous application. Due to proprietary third party software, this structure cannot be changed. I am looking for some way to allow the app and the widgets to communicate, allowing the app to make changes to the widgets and the the widgets to notify the app when events are triggered, so that user interaction is fluid and continuous. There are a few related questions which indicate it's possible to do this by setting up event triggers and listeners. I am wondering if there is any standardized way to do this (the answers aren't very clear) or if anyone has developed a library or API to make this easier.

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  • Resources for memory management in embedded application

    - by Elazar Leibovich
    How should I manage memory in my mission critical embedded application? I found some articles with google, but couldn't pinpoint a really useful practical guide. The DO-178b forbids dynamic memory allocations, but how will you manage the memory than? preallocate everything in advance and send a pointer to each function that needs allocation? Allocate it on the stack? Use a global static allocator (but then it's very similar to dynamic allocation)? Answers can be of the form of regular answer, reference to a resource, or reference to good opensource embedded system for example. clarification: The issue here is not whether or not memory management is availible for the embedded system. But what is a good design for an embedded system, to maximize reliability.

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  • Django refresh page if change data by other user

    - by Fran Sobrino
    I have a test django app. In one page the test show the same question to all users. I'd like that when a user answers correctly, send a signal to other active user's browser to refresh to the next question. I have been learning about signals in django I learning work with them but I don't now how send the "refresh signal" to client browser. I think that it can do with a javascript code that check if a certain value (actual question) change and if change reload the page but I don't know this language and the information that I find was confused. Can anybody help me? Many Thanks.

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  • Data Warehouse: One Database or many?

    - by drrollins
    At my new company, they keep all data associated with the data warehouse, including import, staging, audit, dimension and fact tables, together in the same physical database. I've been a database developer for a number of years now and this consolidation of function and form seems counter to everything I know. It seems to make security, backup/restore and performance management issues more manually intensive. Is this something that is done in the industry? Are there substantial reasons for doing or not doing it? The platform is Netezza. The size is in terabytes, hundreds of millions of rows. What I'm looking to get from answers to this question is a solid understanding of how right or wrong this path is. From your experience, what are the issues I should be focused on arguing if this is a path that will cause trouble for us down the road. If it is no big deal, then I'd like to know that as well.

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  • iphone web app: open directions in external maps application

    - by munchybunch
    I've seen the answers for opening the Maps app in a native iPhone app, but is there any way to do this in a web app? I've tried changing window.location to http://maps.google.com/maps?q=cupertino for example, to no avail. I've tried using a simple anchor tag linked to http://maps.google.com/maps?q=cupertino, also to no avail. Has anyone gotten this to work before? I'm working on a map-heavy application, and I'd like to provide users with directions at the end. I figured it would be easiest to simply open it up in the Map application. Note: I'm currently testing with just the simulator, could that lead to problems? My iPhone is down for the count at the moment.

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  • System.Net.WebClient Class in .Net CompactFramework 3.5 ?

    - by Leen15
    Hi at all! I need to comunicate with a Server that give me async answers (streamer connection). I find this: http://msdn.microsoft.com/en-en/library/ms144211%28v=VS.80%29.aspx that generate this event: http://msdn.microsoft.com/en-en/library/system.net.webclient.openreadcompleted%28v=VS.80%29.aspx I think this is what i need, but i don't have the WebClient class in my System.Net of CompactFramework 3.5. How can i do? Thanks. EDIT: I've done a more clear question: httpRequest, httpResponse, send GET through Stream and Receive the Result in C#

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  • Abstract Classes and ReadOnly Properties

    - by serhio
    Let's have three classes; Line PoliLine SuperPoliLine for all that three classes a Distance is defined. But only for the Line a Distance can be Set. Is there a possibility to build a common abstract (MustInherit) class Segment, having a Distance as (abstract +? ReadOnly) member? Question for VB.NET, but C# answers welcomed too. Business Background Imagine a Bus. It has a lot of Stations, MainStations, and 2 TerminalStations. So Line is between 2 Stations, PoliLine is between 2 MainStations, and SuperPoliLine is between 2 TerminalStations. All "lines" are "Segments", but only the distance A-B between 2 stations - Line can be defined.

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  • Is there a way to set up a Linux pipe to non-buffering or line-buffering?

    - by ern0
    My program is controlling an external application on Linux, passing in input commands via a pipe to the external applications stdin, and reading output result via a pipe from the external applications stdout. The problem is that writes to pipes are buffered by block, and not by line, and therefore delays occur before my app receives data output by the external application. The external application cannot be altered to add explicit fflush() calls. When I set the external application to /bin/cat -n (it echoes back the input, with line numbers added), it works correctly, it seems, cat flushes after each line. The only way to force the external application to flush, is sending exit command to it; as it receives the command, it flushes, and all the answers appears on the stdout, just before exiting. I'm pretty sure, that Unix pipes are appropiate solution for that kind of interprocess communication (pseudo server-client), but maybe I'm wrong. (I've just copied some text from a similar question: Force another program's standard output to be unbuffered using Python)

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  • How can I find out how many rows of a matrix satisfy a rather complicated criterion (in R)?

    - by Brani
    As an example, here is a way to get a matrix of all possible outcomes of rolling 4 (fair) dice. z <- as.matrix(expand.grid(c(1:6),c(1:6),c(1:6),c(1:6))) As you may already have understood, I'm trying to work out a question that was closed, though, in my opinion, it's a challenging one. I used counting techniques to solve it (I mean by hand) and I finaly arrived to a number of outcomes, with a sum of subset being 5, equal to 1083 out of 1296. That result is consistent with the answers provided to that question, before it was closed. I was wondering how could that subset of outcomes (say z1, where dim(z1) = [1083,4] ) be generated using R. Do you have any ideas? Thank you.

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  • Create instance of generic type in Java?

    - by David Citron
    Is it possible to create an instance of a generic type in Java? I'm thinking based on what I've seen that the answer is "no" (due to type erasure), but I'd be interested if anyone can see something I'm missing: class SomeContainer<E> { E createContents() { return what??? } } EDIT: It turns out that Super Type Tokens could be used to resolve my issue, but it requires a lot of reflection-based code, as some of the answers below have indicated. I'll leave this open for a little while to see if anyone comes up with anything dramatically different than Ian Robertson's Artima Article.

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  • How Proxy server works with tcp/http connections?

    - by Vivek
    Since I am a beginner in the world of internet/networking, I always mess up with these kinds of doubts in my head while programming ;) .. My doubts are, While working behind a proxy, how my requests and responses work? Means my request headers and data will first reach to Proxy server- then proxy server sends it(same headers and data) to corresponding server. And server responses to it with a response header and body to the proxy server-then proxy server sends it to my computer. Wright? While using websockets we are upgrading our http connection to tcp. At this time what is happening @ Proxy server? Does the proxyserver also upgrades its connection to plain TCP? After opening such TCP connections, does the proxy server able to track/log those socket messsages? And most importantly, Is the proxy server transparent or acting like an original server infront of a client? Thanks for any answers or helpful links in advance.

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  • How to extract a single function from a source file

    - by Adam Matan
    Hi, I'm working on a small academic research about extremely long and complicated functions in the Linux kernel. I'm trying to figure out if there is a good reason to write 600 or 800 lines-long functions. For that purpose, I would like to find a tool that can extract a function from a .c file, so I can run some automated tests on the function. For example, If I have the function cifs_parse_mount_options() within the file connect.c, I'm seeking a solution that would roughly work like: extract /fs/cifs/connect.c cifs_parse_mount_options and return the 523 lines of code(!) of the function, from the opening braces to the closing braces. Of course, any way of manipulating existing software packages like gcc to do that, would be most helpful too. Thanks, Udi EDIT : The answers to Regex to pull out C function prototype declarations? convinced me that matching function declaration by regex is far from trivial.

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  • MySQL: check whether two fields on a model are always the same?

    - by AP257
    Sorry if this is a duplicate question, I'm a total database newbie and I'm probably using the wrong terminology to search for answers. I have a MySQL table as follows: +------------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +------------+---------------+------+-----+---------+-------+ | placeid | int(11) | NO | PRI | NULL | | | grid | varchar(120) | YES | | NULL | | | vill | varchar(300) | YES | | NULL | | +------------+---------------+------+-----+---------+-------+ I'd like to find out whether 'grid' and 'vill' always occur in the same combinations or not. Maybe it'd be clearer with an example: placeid, grid, vill 1, TM1, Suffolk 2, TM1, Suffolk 3, WA8, Newcastle 4, WA8, Newcastle 5, WA8, York I'd like to construct a query that returns 'WA8' but not 'TM1', because 'WA8' occurs in combination with more than one vill. I would be SO grateful for any help!

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  • Abstracting the adding of click events to elements selected by class using jQuery

    - by baroquedub
    I'm slowly getting up to speed with jQuery and am starting to want to abstract my code. I'm running into problems trying to define click events at page load. In the code below, I'm trying to run through each div with the 'block' class and add events to some of its child elements by selecting them by class: <script language="javascript" type="text/javascript"> $(document).ready(function (){ $('HTML').addClass('JS'); // if JS enabled, hide answers $(".block").each(function() { problem = $(this).children('.problem'); button = $(this).children('.showButton'); problem.data('currentState', 'off'); button.click(function() { if ((problem.data('currentState')) == 'off'){ button.children('.btn').html('Hide'); problem.data('currentState', 'on'); problem.fadeIn('slow'); } else if ((problem.data('currentState')) == 'on'){ button.children('.btn').html('Solve'); problem.data('currentState', 'off'); problem.fadeOut('fast'); } return false; }); }); }); </script> <style media="all" type="text/css"> .JS div.problem{display:none;} </style> <div class="block"> <div class="showButton"> <a href="#" title="Show solution" class="btn">Solve</a> </div> <div class="problem"> <p>Answer 1</p> </div> </div> <div class="block"> <div class="showButton"> <a href="#" title="Show solution" class="btn">Solve</a> </div> <div class="problem"> <p>Answer 2</p> </div> </div> Unfortunately using this, only the last of the divs' button actually works. The event is not 'localised' (if that's the right word for it?) i.e. the event is only applied to the last $(".block") in the each method. So I have to laboriously add ids for each element and define my click events one by one. Surely there's a better way! Can anyone tell me what I'm doing wrong? And how I can get rid of the need for those IDs (I want this to work on dynamically generated pages where I might not know how many 'blocks' there are...) <script language="javascript" type="text/javascript"> $(document).ready(function (){ $('HTML').addClass('JS'); // if JS enabled, hide answers // Preferred version DOESN'T' WORK // So have to add ids to each element and laboriously set-up each one in turn... $('#problem1').data('currentState', 'off'); $('#showButton1').click(function() { if (($('#problem1').data('currentState')) == 'off'){ $('#showButton1 > a').html('Hide'); $('#problem1').data('currentState', 'on'); $('#problem1').fadeIn('slow'); } else if (($('#problem1').data('currentState')) == 'on'){ $('#showButton1 > a').html('Solve'); $('#problem1').data('currentState', 'off'); $('#problem1').fadeOut('fast'); } return false; }); $('#problem2').data('currentState', 'off'); $('#showButton2').click(function() { if (($('#problem2').data('currentState')) == 'off'){ $('#showButton2 > a').html('Hide'); $('#problem2').data('currentState', 'on'); $('#problem2').fadeIn('slow'); } else if (($('#problem2').data('currentState')) == 'on'){ $('#showButton2 > a').html('Solve'); $('#problem2').data('currentState', 'off'); $('#problem2').fadeOut('fast'); } return false; }); }); </script> <style media="all" type="text/css"> .JS div.problem{display:none;} </style> <div class="block"> <div class="showButton" id="showButton1"> <a href="#" title="Show solution" class="btn">Solve</a> </div> <div class="problem" id="problem1"> <p>Answer 1</p> </div> </div> <div class="block"> <div class="showButton" id="showButton2"> <a href="#" title="Show solution" class="btn">Solve</a> </div> <div class="problem" id="problem2"> <p>Answer 2</p> </div> </div>

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  • Create "duplicate copy" of github repository

    - by user1483934
    I see answers to similar questions and I'm sure I may just not be familiar enough with Git and Github terminology to know if they apply to my question. What I need to do is to clone an existing Github remote repository (a private repo under another person's username that I have contributor access to) and create a new private remote repo under my account. The existing repo user is going to make significant alterations to the repo, delete, and re-push, before they do that they want me to clone and create a duplicate so we can continue working from the repo under my user. I want to preserve the commit history with the repo if possible. I've cloned locally but don't can't seem to figure out how to push it to a new remote that isn't origined to the original user.

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  • How to parse a string to an integer without library functions?

    - by dack
    Hi, I was recently asked this question in an interview: "How could you parse a string of the form '12345' into its integer representation 12345 without using any library functions, and regardless of language?" I thought of two answers, but the interviewer said there was a third. Here are my two solutions: Solution 1: Keep a dictionary which maps '1' = 1, '2' = 2, etc. Then parse the string one character at a time, look up the character in your dictionary, and multiply by place value. Sum the results. Solution 2: Parse the string one character at a time and subtract '0' from each character. This will give you '1' - '0' = 0x1, '2' - '0' = 0x2, etc. Again, multiply by place value and sum the results. Can anyone think of what a third solution might be? Thanks.

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  • What's quicker and better to determine if an array key exists in PHP?

    - by alex
    Consider these 2 examples $key = 'jim'; // example 1 if (isset($array[$key])) { doWhatIWant(); } // example 2 if (array_key_exists($key, $array)) { doWhatIWant(); } I'm interested in knowing if either of these are better. I've always used the first, but have seen a lot of people use the second example on this site. So, which is better? Faster? Clearer intent? Update Thanks for the quality answers. I now understand the difference between the 2. A benchmark states that isset() alone is quicker than array_key_exists(). However, if you want the isset() to behave like array_key_exists() it is slower.

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  • Is it possible to set different select2 parameters at different times?

    - by ReiMasuro
    From playing around I can see that this code $("#Selected3").select2({ minimumInputLength: 3 }); $("#Selected3").select2({ placeholder: "Show a placeholder" }); will show me the placeholder but remove the minimumInputLength parameters value. Does anyone know a way please that this example could be modified so that the placeholder will be added without losing the minimum..Length value. Any answers will need to allow for the possibility of the statements being in separate files, i.e. one on the page and another in a referenced .js file. I am aware that this would be much easier if I set all the parameters at once, e.g. $("#Selected3").select2({ minimumInputLength: 3, placeholder: "Show a placeholder" }); but I am working within a framework which won't currently allow that. EDIT: For anyone who is willing to give this a shot but doesn't know select2 the library comes from here Select2 on GitHub

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  • Please explain this php expression "!$variable"

    - by DogBot
    What does an exclamaton mark in front of a variable mean? And how is it being used in this piece of code? EDIT: From the answers so far I suspect that I also should mention that this code is in a function where one of the parameters is $mytype ....would this be a way of checking if $mytype was passed? - Thanks to all of the responders so far. $myclass = null; if ($mytype == null && ($PAGE->pagetype <> 'site-index' && $PAGE->pagetype <>'admin-index')) { return $myclass; } elseif ($mytype == null && ($PAGE->pagetype == 'site-index' || $PAGE->pagetype =='admin-index')) { $myclass = ' active_tree_node'; return $myclass; } elseif (!$mytype == null && ($PAGE->pagetype == 'site-index' || $PAGE->pagetype =='admin-index')) { return $myclass; }`

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  • Composite primary keys in N-M relation or not?

    - by BerggreenDK
    Lets say we have 3 tables (actually I have 2 at the moment, but this example might illustrate the thought better): [Person] ID: int, primary key Name: nvarchar(xx) [Group] ID: int, primary key Name: nvarchar(xx) [Role] ID: int, primary key Name: nvarchar(xx) [PersonGroupRole] Person_ID: int, PRIMARY COMPOSITE OR NOT? Group_ID: int, PRIMARY COMPOSITE OR NOT? Role_ID: int, PRIMARY COMPOSITE OR NOT? Should any of the 3 ID's in the relation PersonGroupRole be marked as PRIMARY key or should they all 3 be combined into one composite?? whats the real benefit of doing it or not? I can join anyways as far as I know, so Person JOIN PersonGroupRole JOIN Group gives me which persons are in which Groups etc. I will be using LINQ/C#/.NET on top of SQL-express and SQL-server, so if there is any reasons regarding language/SQL that might make the choice more clear, thats the platform I ask about. Looking forward to see what answers pops up, as I have thought of these primary keys/indexes many times when making combined ones.

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  • Pushing app to heroku error

    - by Ryan Max
    Hello, I am getting the following error when I try to push my app to heroku. I saw a similar thread on here, but the issues seemed related to OSX. I am running windows 7 $ git push heroku master Counting objects: 1652, done. Delta compression using up to 4 threads. fatal: object 91f5d3ee9e2edcd42e961ed2eb254d5181cbc734 inconsistent object lengt h (476 vs 8985) error: pack-objects died with strange error error: failed to push some refs to '[email protected]:floating-stone-94.git I'm not sure what this means. I can't find any consistent answers on the internet. I tried re-creating my ssh public key but still the same.

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