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  • Good concurrency example of Java vs. Clojure

    - by Michiel Borkent
    Clojure is said to be a language that makes multi-thread programming easier. From the Clojure.org website: Clojure simplifies multi-threaded programming in several ways. Now I'm looking for a non-trivial problem solved in Java and in Clojure so I can compare/contrast their simplicity. Anyone?

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  • Pros & Cons: Hibernate vs. EJB 3

    - by Zack
    What are the advantages and disadvantages of Hibernate & EJB3 relative to each other? I found this post, but it didn't really address my question. If I don't have any particular tie to either technology, what would cause me to pick one over the other? Or are there situations where I would want to use both? Thanks, Zack

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  • Possible compiler bug in MSVC12 (VS2013) with designated initializer

    - by diapir
    Using VS2013 Update 2, I've stumbled on some strange error message : // test.c int main(void) { struct foo { int i; float f; }; struct bar { unsigned u; struct foo foo; double d; }; struct foo some_foo = { .i = 1, .f = 2.0 }; struct bar some_bar = { .u = 3, // error C2440 : 'initializing' : cannot convert from 'foo' to 'int' .foo = some_foo, .d = 4.0 }; // Works fine some_bar.foo = some_foo; return 0; } Both GCC and Clang accept it. Am I missing something or does this piece of code exposes a compiler bug ? EDIT : Duplicate: Initializing struct within another struct using designated initializer causes compile error in Visual Studio 2013

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  • Microsoft Access vs Native SQL

    - by ktm5124
    Hypothetical: Let's say you are writing complex queries to a database and it is very important that the data you extracted is the correct result set (e.g., that you didn't mess up a JOIN by not using all the correct keys, and all the other things that can go wrong, et cetera). What would you rather use to do this? Would you write the query using Microsoft Access and its Design View, or would you write it in native SQL using a SQL IDE? What is the better professional choice? Thanks in advance your feedback!

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  • ModelName(django.contrib.auth.models.User) vs ModelName(models.Model)

    - by amr.negm
    I am developing a django project. I created some apps, some of those are related to User model, for instance, I have a feeds app that handles user feeds, and another app that deals with extra user data like age, contacts, and friends. for each of these, I created a table that should be connected to the User model, which I using for storing and authenticating users. I found two ways to deal with this issue. One, is through extending User model to be like this: ModelName(User): friends = models.ManyToMany('self') ..... Two, is through adding a foreign key to the new table like this: ModelName(models.Model): user = models.ForeignKey(User, unique=True) friends = friends = models.ManyToMany('self') ...... I can't decide which to use in which case. in other words, what are the core differences between both?

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  • typeof === "undefined" vs. != null

    - by Thor Thurn
    I often see JavaScript code which checks for undefined parameters etc. this way: if (typeof input !== "undefined") { // do stuff } This seems kind of wasteful, since it involves both a type lookup and a string comparison, not to mention its verbosity. It's needed because 'undefined' could be renamed, though. My question is: How is that code any better than this approach: if (input != null) { // do stuff } As far as I know, you can't redefine null, so it's not going to break unexpectedly. And, because of the type-coercion of the != operator, this checks for both undefined and null... which is often exactly what you want (e.g. for optional function parameters). Yet this form does not seem widespread, and it even causes JSLint to yell at you for using the evil != operator. Why is this considered bad style?

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  • C++ class member functions instantiated by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched Stack Overflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instantiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits that are tested at runtime. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state information was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. The compiler (VC++ 2008) always complained that things didn't match. I would yell, "SFINAE, you moron!" but the moron is probably me. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice?

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  • Console in VS 2012 Express for C++?

    - by Live2Code
    I'm very new to programming, so be nice. I was using Eclipse for C/C++ devs for a while, but it seemed quite buggy so I was advised to switch to Visual Studio Express. I'm just testing out with a simple "Hello World" program #include <iostream> #include <string> using namespace std; int main( int argc, char ** argv ) { string response; cout << "Gimme a string: " << flush; cin >> response; cout << "The string is: " << response << endl; system("pause"); return 0; } not much to go wrong there anyway, I noticed that there is no "console" like in Eclipse. All of the text pops up in a little command prompt window. And, also, this window closes right after displaying new text if there is no other things to do after it (like a cin). I have been told that I can use system("pause") but there has to be a better way. In Eclipse, the text would not suddenly disappear because the console window closed. i know this question might be a little confusing, comment and I'll try to explain what I'm saying. Or paste the codes into your Visual Studio 2012 Express Edition. But is there a way to display all of my text and whatever in a "console" as opposed to a command prompt-type window; and why does it always close before I can read the last thing?

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  • Cannot customize Solution Explorer project context menu in VS 2010

    - by mikoro
    I'm trying to customize that context menu which comes up when you right click the project in the Solution Explorer. When I goto: Tools - Customize - Commands - Context Menu (radio button) - Project and Solution Context Menus | Project (drop down) I get nothing in the "controls:" list. I can modify other context menus starting with "Project and Solution Context Menus" but none of them is the right one. Any ideas? Currently I have ReSharper, PowerTools and StyleCop installed, but I have installed and uninstalled bunch of other addins (dotTrace, CodeIt.Right, VisualHG, DevExpress, random stuff from Extension Manager).

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  • C++ arrays as parameters, subscript vs. pointer

    - by awshepard
    Alright, I'm guessing this is an easy question, so I'll take the knocks, but I'm not finding what I need on google or SO. I'd like to create an array in one place, and populate it inside a different function. I define a function: void someFunction(double results[]) { for (int i = 0; i<100; ++i) { for (int n = 0; n<16; ++n) //note this iteration limit { results[n] += i * n; } } } That's an approximation to what my code is doing, but regardless, shouldn't be running into any overflow or out of bounds issues or anything. I generate an array: double result[16]; for(int i = 0; i<16; i++) { result[i] = -1; } then I want to pass it to someFunction someFunction(result); When I set breakpoints and step through the code, upon entering someFunction, results is set to the same address as result, and the value there is -1.000000 as expected. However, when I start iterating through the loop, results[n] doesn't seem to resolve to *(results+n) or *(results+n*sizeof(double)), it just seems to resolve to *(results). What I end up with is that instead of populating my result array, I just get one value. What am I doing wrong?

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  • LINQ extention SelectMany in 3.5 vs 4.0?

    - by Moberg
    Hi When I saw Darins suggestion here .. IEnumerable<Process> processes = new[] { "process1", "process2" } .SelectMany(Process.GetProcessesByName); ( http://stackoverflow.com/questions/3059667/process-getprocessesbyname/3059733#3059733 ) .. I was a bit intrigued and I tried it in VS2008 with .NET 3.5 - and it did not compiling unless I changed it to .. IEnumerable<Process> res = new string[] { "notepad", "firefox", "outlook" } .SelectMany(s => Process.GetProcessesByName(s)); Having read some Darins answers before I suspected that it was me that were the problem, and when I later got my hands on a VS2010 with.NET 4.0 - as expected - the original suggestion worked beautifully. My question is : What have happend from 3.5 to 4.0 that makes this (new syntax) possible? Is it the extentionmethods that have been extended(hmm) or new rules for lambda syntax or? I've tried to search but my google-fu was not strong enough. Please forgive if the question is a bit naive and note that I've taged it as beginner :)

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  • Behaviour difference Dim oDialog1 as Dialog1 = New Dialog1 VS Dim oDialog1 as Dialog1 = Dialog1

    - by user472722
    VB.Net 2005 I have a now closed Dialog1. To get information from the Dialog1 from within a module I need to use Dim oDialog1 as Dialog1 = New Dialog1. VB.Net 2008 I have a still open Dialog1. To get information from the Dialog1 from within a module I need to use Dim oDialog1 as Dialog1 = Dialog1. VB.Net 2005 does not compile using Dim oDialog1 as Dialog1 = Dialog1 and insists on NEW What is going on and why do I need the different initialisation syntax?

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  • Import CSV to class structure as the user defines

    - by Assimilater
    I have a contact manager program and I would like to offer the feature to import csv files. The problem is that different data sources order the fields in different ways. I thought of programming an interface for the user to tell it the field order and how to handle exceptions. Here is an example line in one of many possible field orders: "ID#","Name","Rank","Address1","Address2","City","State","Country","Zip","Phone#","Email","Join Date","Sponsor ID","Sponsor Name" "Z1234","Call, Anson","STU","1234 E. 6578 S.","","Somecity","TX","United States","012345","000-000-0000","[email protected]","5/24/2010","z12343","Quantum Independence" Notice that in one data field "Name" there is a comma to separate last name and first name and in another there is not. My plan is to have a line for each field (ie ID, Name, City etc.) and a statement "import to" and list box with options like: Don't Import, BusinessJoin Date, First Name, Zip and the program recognizes those as properties of an object... I'd also like the user to be able to record preset field orders so they can re-use them for csv files from the same download source. Then I also need it to check if a record all ready exists (is there a record for Anson Call all ready?) and allow the user to tell it what to do if there is a record (ie mailing address may have changes, so if that field is filled overwrite it, or this mailing address is invalid, leave the current data untouched for this person, overwrite the rest). While I'm capable of coding this...i'm not very excited about it and I'm wondering if there's a tool or set of tools out there to all ready perform most of this functionality... I hope this makes sense...

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  • VS 2008 Open Word Document - Memory Error

    - by Lord Darkside
    I am executing the following code that worked fine in a vs2003(1.1) but seems to have decided otherwise now that I'm using vs2008(2.0/3.5): Dim wordApp As Microsoft.Office.Interop.Word.Application Dim wordDoc As Microsoft.Office.Interop.Word.Document missing = System.Reflection.Missing.Value wordApp = New Microsoft.Office.Interop.Word.Application() Dim wordfile As Object wordfile = "" ' path and file name goes here wordDoc = wordApp.Documents.Open(wordfile, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing) The error thrown when the Open is attempted is : "Attempted to read or write protected memory. This is often an indication that other memory is corrupt." Does anyone have any idea how to correct this?

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  • C++ STL Map vs Vector speed

    - by sub
    In the interpreter for my experimental programming language I have a symbol table. Each symbol consists of a name and a value (the value can be e.g.: of type string, int, function, etc.). At first I represented the table with a vector and iterated through the symbols checking if the given symbol name fitted. Then I though using a map, in my case map<string,symbol>, would be better than iterating through the vector all the time but: It's a bit hard to explain this part but I'll try. If a variable is retrieved the first time in a program in my language, of course its position in the symbol table has to be found (using vector now). If I would iterate through the vector every time the line gets executed (think of a loop), it would be terribly slow (as it currently is, nearly as slow as microsoft's batch). So I could use a map to retrieve the variable: SymbolTable[ myVar.Name ] But think of the following: If the variable, still using vector, is found the first time, I can store its exact integer position in the vector with it. That means: The next time it is needed, my interpreter knows that it has been "cached" and doesn't search the symbol table for it but does something like SymbolTable.at( myVar.CachedPosition ). Now my (rather hard?) question: Should I use a vector for the symbol table together with caching the position of the variable in the vector? Should I rather use a map? Why? How fast is the [] operator? Should I use something completely different?

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  • Android -- Object Creation/Memory Allocation vs. Performance

    - by borg17of20
    Hello all, This is probably an easy one. I have about 20 TextViews/ImageViews in my current project that I access like this: ((TextView)multiLayout.findViewById(R.id.GameBoard_Multi_Answer1_Text)).setText(""); //or ((ImageView)multiLayout.findViewById(R.id.GameBoard_Multi_Answer1_Right)).setVisibility(View.INVISIBLE); My question is this, am I better off, from a performance standpoint, just assigning these object variables? Further, am I losing some performance to the constant "search" process that goes on as a part of the findViewById(...) method? (i.e. Does findsViewById(...) use some sort of hashtable/hashmap for look-ups or does it implement an iterative search over the view hierarchy?) At present, my program never uses more than 2.5MB of RAM, so will assigning 20 or so more object variables drastically affect this? I don't think so, but I figured I'd ask. Thanks.

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  • gnuplot - multiple lines with different x ranges

    - by Aly
    Hi, I am using gnuplot to try and plot several lines but each have different x ranges. I am running the following script: # gnuplot script for 'omarConf2EvONLY-vs-everyone-gta-lag-lpas-omarConf1-random-tag-tpas.dat' plot "omarConf2EvONLY-vs-everyone-gta-lag-lpas-omarConf1-random-tag-tpas.dat" using 1:2 with lines title '1' replot "omarConf2EvONLY-vs-everyone-gta-lag-lpas-omarConf1-random-tag-tpas.dat" using 1:3 with lines title '2' replot "omarConf2EvONLY-vs-everyone-gta-lag-lpas-omarConf1-random-tag-tpas.dat" using 1:4 with lines title '3' replot "omarConf2EvONLY-vs-everyone-gta-lag-lpas-omarConf1-random-tag-tpas.dat" using 1:5 with lines title '4' replot "omarConf2EvONLY-vs-everyone-gta-lag-lpas-omarConf1-random-tag-tpas.dat" using 1:6 with lines title '5' replot "omarConf2EvONLY-vs-everyone-gta-lag-lpas-omarConf1-random-tag-tpas.dat" using 1:7 with lines title '6' replot "omarConf2EvONLY-vs-everyone-gta-lag-lpas-omarConf1-random-tag-tpas.dat" using 1:8 with lines title '7' set terminal png size 800,600 set output "omar_vs_everyone-EVONLY.png" replot and the .dat file is just a file with columns such as: 1 0.5 0.5 0.1 2 0.6 1.3 0.8 3 0.7 0.32 4 0.7 0.35 5 1.3 4.32 6 1.67 notice that the columns have different lengths as each line has different x ranges. The problem I have is that it plots funny as shown below:

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  • Sql Server Replication: Snapshot vs Merge

    - by Zyphrax
    Background information Let's say I have two database servers, both SQL Server 2008. One is in my LAN (ServerLocal), the other one is on a remote hosting environment (ServerRemote). I have created a database on ServerLocal and have an exact copy of that database on ServerRemote. The database on ServerRemote is part of a web application and I would like to keep it's data up-to-date with the data in the database ServerLocal. ServerLocal is able to communicate with ServerRemote, this is one-way traffic. Communication from ServerRemote to ServerLocal isn't available. Current solution I thought it would be a nice solution to use replication. So I've made ServerLocal a publisher and subscriptions are pushed to the ServerRemote. This works fine, when a snapshot is transfered to ServerRemote the existing data will be purged and the ServerRemote database is once again an exact replica of the database on ServerLocal. The problem Records that exist on ServerRemote that don't exist on ServerLocal are removed. This doesn't matter for most of my tables but in some of my tables I'd like to keep the existing data (aspnet_users for instance), and update the records if necessary. What kind of replication fits my problem?

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  • URIs vs Hidden Forms

    - by NateDogg
    I'm working in the Codeigniter framework, and want to send requests to my controller/model that have several variables involved. Is there a difference between passing those variables via a hidden form (i.e. using "post") as opposed to passing them through URIs (e.g. 'travel/$month/$day/')? What about security concerns? e.g. URIs: http://www.example.com/travel/$month/$day/ Hidden Form: form_hidden('month',$month); form_hidden('day',$day);

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  • Php code not executing - dies out when trying to refer to member of static class - no error displaye

    - by Ali
    I'm having some problems with this piece of code. I've included a class declaration and trying to create an object of that class but my code dies out. It doesn't seem to be an include issue as all the files are being included even the files called for inclusion within the class file itself. However the object is not created - I tried to put an echo statement in the __construct function but nothing it just doesn't run infact doesn't create the object and the code won't continue from there - plus no error is reported or displayed and I have error reporting set to E_ALL and display errors set to true WHats happening here :( =============EDIT SOrry I checked again the error is prior to teh object creation thing - it dies out when it tries to refer to a constant in a static class like so: $v = Zend_Oauth::REQUEST_SCHEME_HEADER; THis is the class or part of it - it has largely static functions its the Zend Oauth class: class Zend_Oauth { const REQUEST_SCHEME_HEADER = 'header'; const REQUEST_SCHEME_POSTBODY = 'postbody'; const REQUEST_SCHEME_QUERYSTRING = 'querystring'; // continued LIke I said no error is being reported at all :(

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