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  • Better language or checking tool?

    - by rwallace
    This is primarily aimed at programmers who use unmanaged languages like C and C++ in preference to managed languages, forgoing some forms of error checking to obtain benefits like the ability to work in extremely resource constrained systems or the last increment of performance, though I would also be interested in answers from those who use managed languages. Which of the following would be of most value? A language that would optionally compile to CLR byte code or to machine code via C, and would provide things like optional array bounds checking, more support for memory management in environments where you can't use garbage collection, and faster compile times than typical C++ projects. (Think e.g. Ada or Eiffel with Python syntax.) A tool that would take existing C code and perform static analysis to look for things like potential null pointer dereferences and array overflows. (Think e.g. an open source equivalent to Coverity.) Something else I haven't thought of. Or put another way, when you're using C family languages, is the top of your wish list more expressiveness, better error checking or something else? The reason I'm asking is that I have a design and prototype parser for #1, and an outline design for #2, and I'm wondering which would be the better use of resources to work on after my current project is up and running; but I think the answers may be useful for other tools programmers also. (As usual with questions of this nature, if the answer you would give is already there, please upvote it.)

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  • More efficient R / Sweave / TeXShop work-flow?

    - by user594795
    I've now got everything to work properly on my Mac OS X 10.6 machine so that I can create decent looking LaTeX documents with Sweave that include snippets of R code, output, and LaTeX formatting together. Unfortunately, I feel like my work-flow is a bit clunky and inefficient: Using TextWrangler, I write LaTeX code and R code (surrounded by <<= above and @ below R code chunk) together in one .Rnw file. After saving changes, I call the .Rnw file from R using the Sweave command Sweave(file="/Users/mymachine/Documents/Assign4.Rnw", syntax="SweaveSyntaxNoweb") In response, R outputs the following message: You can now run LaTeX on 'Assign4.tex' So then I find the .tex file (Assign4.tex) in the R directory and copy it over to the folder in my documents ~/Documents/ where the .Rnw file is sitting (to keep everything in one place). Then I open the .tex file (e.g. Assign4.tex) in TeXShop and compile it there into pdf format. It is only at this point that I get to see any changes I have made to the document and see if it 'looks nice'. Is there a way that I can compile everything with one button click? Specifically it would be nice to either call Sweave / R directly from TextWrangler or TeXShop. I suspect it might be possible to code a script in Terminal to do it, but I have no experience with Terminal. Please let me know if there's any other things I can do to streamline or improve my work flow.

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  • mysterical error

    - by Görkem Buzcu
    i get "customer_service_simulator.exe stopped" error, but i dont know why? this is my c programming project and i have limited time left before deadline. the code is: #include <stdio.h> #include <stdlib.h> #include<time.h> #define FALSE 0 #define TRUE 1 /*A Node declaration to store a value, pointer to the next node and a priority value*/ struct Node { int priority; //arrival time int val; //type int wait_time; int departure_time; struct Node *next; }; Queue Record that will store the following: size: total number of elements stored in the list front: it shows the front node of the queue (front of the queue) rear: it shows the rare node of the queue (rear of the queue) availability: availabity of the teller struct QueueRecord { struct Node *front; struct Node *rear; int size; int availability; }; typedef struct Node *niyazi; typedef struct QueueRecord *Queue; Queue CreateQueue(int); void MakeEmptyQueue(Queue); void enqueue(Queue, int, int); int QueueSize(Queue); int FrontOfQueue(Queue); int RearOfQueue(Queue); niyazi dequeue(Queue); int IsFullQueue(Queue); int IsEmptyQueue(Queue); void DisplayQueue(Queue); void sorteddequeue(Queue); void sortedenqueue(Queue, int, int); void tellerzfunctionz(Queue *, Queue, int, int); int main() { int system_clock=0; Queue waitqueue; int exit, val, priority, customers, tellers, avg_serv_time, sim_time,counter; char command; waitqueue = CreateQueue(0); srand(time(NULL)); fflush(stdin); printf("Enter number of customers, number of tellers, average service time, simulation time\n:"); scanf("%d%c %d%c %d%c %d",&customers, &command,&tellers,&command,&avg_serv_time,&command,&sim_time); fflush(stdin); Queue tellerarray[tellers]; for(counter=0;counter<tellers;counter++){ tellerarray[counter]=CreateQueue(0); //burada teller sayisi kadar queue yaratiyorum } for(counter=0;counter<customers;counter++){ priority=1+(int)rand()%sim_time; //this will generate the arrival time sortedenqueue(waitqueue,1,priority); //here i put the customers in the waiting queue } tellerzfunctionz(tellerarray,waitqueue,tellers,customers); DisplayQueue(waitqueue); DisplayQueue(tellerarray[0]); DisplayQueue(tellerarray[1]); // waitqueue-> printf("\n\n"); system("PAUSE"); return 0; } /*This function initialises the queue*/ Queue CreateQueue(int maxElements) { Queue q; q = (struct QueueRecord *) malloc(sizeof(struct QueueRecord)); if (q == NULL) printf("Out of memory space\n"); else MakeEmptyQueue(q); return q; } /*This function sets the queue size to 0, and creates a dummy element and sets the front and rear point to this dummy element*/ void MakeEmptyQueue(Queue q) { q->size = 0; q->availability=0; q->front = (struct Node *) malloc(sizeof(struct Node)); if (q->front == NULL) printf("Out of memory space\n"); else{ q->front->next = NULL; q->rear = q->front; } } /*Shows if the queue is empty*/ int IsEmptyQueue(Queue q) { return (q->size == 0); } /*Returns the queue size*/ int QueueSize(Queue q) { return (q->size); } /*Shows the queue is full or not*/ int IsFullQueue(Queue q) { return FALSE; } /*Returns the value stored in the front of the queue*/ int FrontOfQueue(Queue q) { if (!IsEmptyQueue(q)) return q->front->next->val; else { printf("The queue is empty\n"); return -1; } } /*Returns the value stored in the rear of the queue*/ int RearOfQueue(Queue q) { if (!IsEmptyQueue(q)) return q->rear->val; else { printf("The queue is empty\n"); return -1; } } /*Displays the content of the queue*/ void DisplayQueue(Queue q) { struct Node *pos; pos=q->front->next; printf("Queue content:\n"); printf("-->Priority Value\n"); while (pos != NULL) { printf("--> %d\t %d\n", pos->priority, pos->val); pos = pos->next; } } void enqueue(Queue q, int element, int priority){ if(IsFullQueue(q)){ printf("Error queue is full"); } else{ q->rear->next=(struct Node *)malloc(sizeof(struct Node)); q->rear=q->rear->next; q->rear->next=NULL; q->rear->val=element; q->rear->priority=priority; q->size++; } } void sortedenqueue(Queue q, int val, int priority) { struct Node *insert,*temp; insert=(struct Node *)malloc(sizeof(struct Node)); insert->val=val; insert->priority=priority; temp=q->front; if(q->size==0){ enqueue(q, val, priority); } else{ while(temp->next!=NULL && temp->next->priority<insert->priority){ temp=temp->next; } //printf("%d",temp->priority); insert->next=temp->next; temp->next=insert; q->size++; if(insert->next==NULL){ q->rear=insert; } } } niyazi dequeue(Queue q) { niyazi del; niyazi deli; del=(niyazi)malloc(sizeof(struct Node)); deli=(niyazi)malloc(sizeof(struct Node)); if(IsEmptyQueue(q)){ printf("Queue is empty!"); return NULL; } else { del=q->front->next; q->front->next=del->next; deli->val=del->val; deli->priority=del->priority; free(del); q->size--; return deli; } } void sorteddequeue(Queue q) { struct Node *temp; struct Node *min; temp=q->front->next; min=q->front; int i; for(i=1;i<q->size;i++) { if(temp->next->priority<min->next->priority) { min=temp; } temp=temp->next; } temp=min->next; min->next=min->next->next; free(temp); if(min->next==NULL){ q->rear=min; } q->size--; } void tellerzfunctionz(Queue *a, Queue b, int c, int d){ int i; int value=0; int priority; niyazi temp; temp=(niyazi)malloc(sizeof(struct Node)); if(c==1){ for(i=0;i<d;i++){ temp=dequeue(b); sortedenqueue((*(a)),temp->val,temp->priority); } } else{ for(i=0;i<d;i++){ while(b->front->next->val==1){ if((*(a+value))->availability==1){ temp=dequeue(b); sortedenqueue((*(a+value)),temp->val,temp->priority); (*(a+value))->rear->val=2; } else{ value++; } } } } } //end of the program

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  • In C/C++ mode in Emacs, change face of code in #if 0...#endif block to comment face

    - by pogopop77
    I'm trying to add functionality found in some other code editors to my Emacs configuration, whereby C/C++ code within #if 0...#endif blocks is automatically set to the comment face/font. Based on my testing, cpp-highlight-mode does something like what I want, but requires user action. It seems like tying into the font-lock functionality is the correct option to make the behavior automatic. I have successfully followed examples in the GNU documentation to change the face of single-line regular expressions. For example: (add-hook 'c-mode-common-hook (lambda () (font-lock-add-keywords nil '(("\\<\\(FIXME\\|TODO\\|HACK\\|fixme\\|todo\\|hack\\)" 1 font-lock-warning-face t))))) works fine to highlight debug related keywords anywhere in a file. However, I am having problems matching #if 0...#endif as a multiline regular expression. I found some useful information in this post (How to compose region like ""), that suggested that Emacs must be told specifically to allow for multiline matches. But this code: (add-hook 'c-mode-common-hook (lambda () '(progn (setq font-lock-multiline t) (font-lock-add-keywords nil '(("#if 0\\(.\\|\n\\)*?#endif" 1 font-lock-comment-face t)))))) still does not work for me. Perhaps my regular expression is wrong (though it appears to work using M-x re-builder), I've messed up my syntax, or I'm following the wrong approach entirely. I'm using Aquamacs 2.1 (which is based on GNU Emacs 23.2.50.1) on OS X 10.6.5, if that makes a difference. Any assistance would be appreciated!

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  • Drools - Doing Complex Stuff inside a Rule Condition or Consequence

    - by mfcabrera
    Hello, In my company we are planning to use Drools a BRE for couple of projects. Now we trying to define some best-practices. My question is what should be and shouldn't be done inside a Rule Condition/Consequence. Given that we can write Java directly or call methods (for example From a Global object in the Working Memory). Example. Given a Rule that evaluates a generic Object (e.g. Person) have property set to true. Now, that specific propertie can only be defined for that Object going to the database and fetching that info. So we have two ways of implementing that: Alternative A: Go to the database and fetch the object property (true/false, a code) Insert the Object in the working memory Evaluate the rule Alternative B: Insert a Global Object that has a method that connects to the database and check for the property for the given object. Insert the Object to eval in Working Memory In the rule, call the Global Object and perform the access to the database Which of those is considered better? I really like A, but sometimes B is more straightforward, however what would happen if something like a Exception from the Database is raised? I have seen the alternative B implemented in the Drools 5.0 Book from Packt Publishing,however they are doing a mocking and they don't talk about the actual implications of going to the database at all. Thank you,

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  • Types in Haskell

    - by Linda Cohen
    I'm kind of new in Haskell and I have difficulty understanding how inferred types and such works. map :: (a -> b) -> [a] -> [b] (.) :: (a -> b) -> (c -> a) -> c -> b What EXACTLY does that mean? foldr :: (a -> b -> b) -> b -> [a] -> b foldl :: (a -> b -> a) -> a -> [b] -> a foldl1 :: (a -> a -> a) -> [a] -> a What are the differences between these? And how would I define the inferred type of something like foldr map THANKS!

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  • Using variables before include()ing them

    - by phenry
    I'm using a file, page.php, as an HTML container for several content files; i.e., page.php defines most of the common structure of the page, and the content files just contain the text that's unique to every page. What I would like to do is include some PHP code with each content file that defines metadata for the page such as its title, a banner graphic to use, etc. For example, a content file might look like this (simplified): <?php $page_title="My Title"; ?> <h1>Hello world!</h1> The name of the file would be passed as a URL parameter to page.php, which would look like this: <html> <head> <title><?php echo $page_title; ?></title> </head> <body> <?php include($_GET['page']); ?> </body> </html> The problem with this approach is that the variable gets defined after it is used, which of course won't work. Output buffering also doesn't seem to help. Is there an alternate approach I can use? I'd prefer not to define the text in the content file as a PHP heredoc block, because that smashes the HTML syntax highlighting in my text editor. I also don't want to use JavaScript to rewrite page elements after the fact, because many of these pages don't otherwise use JavaScript and I'd rather not introduce it as a dependency if I don't have to.

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  • How to force my method to accept objects from external software?

    - by Roman
    I have a method which needs to take a callback object as an argument and then (at the moment when it's needed) my method will call a specific method of the callback object. I wrote a class called Manager which has a method called addListener. As the argument for this method I need to use a callback object which is defined by the external software. So, I define the addListener in the following way: public void addListener(Listener listener). Of course Eclipse complains because it does not know what Listener is (because the Listener is defined by the external software). The only think that I know (should know) about the Listener is that it has a method called doSomething. So, to pleasure Eclipse I add an interface before my Manager class: interface Listener { void doSomething(); } public class CTManager { ... The problem seems to be solved but then I try to test my software. So, I create a class called test. In this class I create an instance of the Manager class and try to use addListener method of this instance. I also create a class Listener, instantiate it and give the instance to the addListener. And it's the place where the problem appears. Eclipse writes that addListener is not applicable to the given argument. I think it's because it expect something from my Listenr interface but gets something from the Listener class. How can I solve this problem?

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  • Python file iterator over a binary file with newer idiom.

    - by drewk
    In Python, for a binary file, I can write this: buf_size=1024*64 # this is an important size... with open(file, "rb") as f: while True: data=f.read(buf_size) if not data: break # deal with the data.... With a text file that I want to read line-by-line, I can write this: with open(file, "r") as file: for line in file: # deal with each line.... Which is shorthand for: with open(file, "r") as file: for line in iter(file.readline, ""): # deal with each line.... This idiom is documented in PEP 234 but I have failed to locate a similar idiom for binary files. I have tried this: >>> with open('dups.txt','rb') as f: ... for chunk in iter(f.read,''): ... i+=1 >>> i 1 # 30 MB file, i==1 means read in one go... I tried putting iter(f.read(buf_size),'') but that is a syntax error because of the parens after the callable in iter(). I know I could write a function, but is there way with the default idiom of for chunk in file: where I can use a buffer size versus a line oriented? Thanks for putting up with the Python newbie trying to write his first non-trivial and idiomatic Python script.

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  • Calling a non-activeX DLL in a VB6 application in Vista/Win7

    - by user1490330
    I have a VB6 app that utilizes a non-activeX DLL (non-registering). It's declared via the classic Public Declare Function "Function Name" Lib "Library.DLL" syntax. On my dev machine (XP) it works fine but when I deploy to Vista or Win7 I'm constantly greeted with a Run Time Error 48 - File Not Found for the DLL in question. I have tried copying that DLL to every directory I can think of including every environment path on the test machine and the app path too. These are all 32-bit test environments so it's not a SysWow64 issue. Possibly throwing a wrench into the mix is the fact that the application in question is an Outlook COM Addin. I managed to install VB6 on Win7 and was able to run a tiny sample app that utilizes this DLL (outside of the Outlook process) so I know it works PROVIDED the DLL is located in App path. If I call App.Path from my DLL when I run it on the test environment it shows, to no surprise, my installation directory however the DLL is there. I tried turning off UAC. I tried making the App.Path directory permissions open to everyone, still no dice.

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  • Using linq2xml to query a single item deep within

    - by BrettRobi
    I'm wondering if there is a robust and graceful way using linq2xml to query an item deep within an xml hierarchy. For example: <?xml version="1.0" encoding="utf-8" ?> <data> <core id="01234"> <field1>some data</field1> <field2>more data</field2> <metadata> <response> <status code="0">Success</status> <content> <job>f1b5c3f8-e6b1-4ae4-905a-a7c5de3f13c6</job> <id>id of the content</id> </content> </response> </metadata> </core> </data> With this xml how do I query the value of without using something like this: var doc = XElement.Load("file.xml"); string id = (string)doc.Element("core") .Element("metadata") .Element("response") .Element("content") .Element("id"); I don't like the above approach because it is error prone (throws exception if any tag is missing in the hierarchy) and honestly ugly. Is there a more robust and graceful approach, perhaps using the sql-like syntax of linq?

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  • Battery drains even with app off screen, could it be Location Services doing it?

    - by John Jorsett
    I run my app, which uses GPS and Bluetooth, then hit the back button so it goes off screen. I verified via LogCat that the app's onDestroy was called. OnDestroy removes the location listeners and shuts down my app's Bluetooth service. I look at the phone 8 hours later and half the battery charge has been consumed, and my app was responsible according the phone's Battery Use screen. If I use the phone's Settings menu to Force Stop the app, this doesn't occur. So my question is: do I need to do something more than remove the listeners to stop Location Services from consuming power? That's the only thing I can think of that would be draining the battery to that degree when the app is supposedly dormant. Here's my onStart() where I turn on the location-related stuff and Bluetooth: @Override public void onStart() { super.onStart(); if(D_GEN) Log.d(TAG, "MainActivity onStart, adding location listeners"); // If BT is not on, request that it be enabled. // setupBluetooth() will then be called during onActivityResult if (!mBluetoothAdapter.isEnabled()) { Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE); startActivityForResult(enableIntent, REQUEST_ENABLE_BT); // Otherwise, setup the Bluetooth session } else { if (mBluetoothService == null) setupBluetooth(); } // Define listeners that respond to location updates mLocationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE); mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, GPS_UPDATE_INTERVAL, 0, this); mLocationManager.addGpsStatusListener(this); mLocationManager.addNmeaListener(this); } And here's my onDestroy() where I remove them: public void onDestroy() { super.onDestroy(); if(D_GEN) Log.d(TAG, "MainActivity onDestroy, removing update listeners"); // Remove the location updates if(mLocationManager != null) { mLocationManager.removeUpdates(this); mLocationManager.removeGpsStatusListener(this); mLocationManager.removeNmeaListener(this); } if(D_GEN) Log.d(TAG, "MainActivity onDestroy, finished removing update listeners"); if(D_GEN) Log.d(TAG, "MainActivity onDestroy, stopping Bluetooth"); stopBluetooth(); if(D_GEN) Log.d(TAG, "MainActivity onDestroy finished"); }

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  • Rails Functional Test Failing Due to Association

    - by Koby
    I have an accounts model that holds some basic account info (account name, website, etc). I then have a user model that has the following in the app/models/user.rb belongs_to :account I also have the following in my routes.rb map.resources :account, :has_many => [:users, :othermodel] the problem I'm facing is that the following test is failing: test "should create user" do assert_difference('User.count') do post :create, :user => { } #this is the line it's actually failing on end assert_redirected_to user_path(assigns(:user)) #it doesn't get here yet end The error it gives is "Can't find Account without ID" so I kind of understand WHY it's failing, because of the fact that it doesn't have the account object (or account_id as it were) to know under what account to create the user. I have tried variations of the following but I am completely lost: post :create, :user => { accounts(:one) } #I have the 'fixtures :accounts' syntax at the top of the test class post :create, [accounts(:one), :user] => { } post :create, :user => { accounts(:one), #other params for :user } and like I said, just about every variation I could think of. I can't find much documentation on doing this and this might be why people have moved to Factories for doing test data, but I want to understand things that come standard in Rails before moving onto other things. Can anyone help me get this working?

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  • How do I insert null fields with Perl's DBD::Pg?

    - by User1
    I have a Perl script inserting data into Postgres according to a pipe delimited text file. Sometimes, a field is null (as expected). However, Perl makes this field into an empty string and the Postgres insert statement fails. Here's a snippet of code: use DBI; #Connect to the database. $dbh=DBI-connect('dbi:Pg:dbname=mydb','mydb','mydb',{AutoCommit=1,RaiseError=1,PrintError=1}); #Prepare an insert. $sth=$dbh-prepare("INSERT INTO mytable (field0,field1) SELECT ?,?"); while (<){ #Remove the whitespace chomp; #Parse the fields. @field=split(/\|/,$_); print "$_\n"; #Do the insert. $sth-execute($field[0],$field[1]); } And if the input is: a|1 b| c|3 EDIT: Use this input instead. a|1|x b||x c|3|x It will fail at b|. DBD::Pg::st execute failed: ERROR: invalid input syntax for integer: "" I just want it to insert a null on field1 instead. Any ideas? EDIT: I simplified the input at the last minute. The old input actually made it work for some reason. So now I changed the input to something that will make the program fail. Also note that field1 is a nullable integer datatype.

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  • Rails load path questions

    - by HelpMe
    Say I have some custom classes that don't belong in models, controllers etc, I should put this in /lib correct? In rails < 3 I would add this directory to my loadpath and in rails 3+ I would add this to my autoload_path. Is this correct? Now say I have some classes that extends already defined classes. Where should I put this so its run on startup. Forexample say I want to add the method 'foo' on String. class String def foo 'foo; end end Where should I put this class so it's defined on startup? Another weird bug I have is when I try to namespace classes in lib. module MyProject class Foo end end Now in a console: ruby-1.9.2-p136 :004 Bags::Foo LoadError: Expected /Users/me/workspace/my_project/lib/foo.rb to define Foo from /Users/rob/.rvm/gems/ruby-1.9.2-p136/gems/activesupport-3.0.3/lib/active_support/dependencies.rb:492:in `load_missing_constant' from /Users/rob/.rvm/gems/ruby-1.9.2-p136/gems/activesupport-3.0.3/lib/active_support/dependencies.rb:183:in `block in const_missing' I keep getting this error. How can I load this file? Thanks in advance for any help!

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  • how to switch views according to command

    - by Veer
    I've a main view and many usercontrols. The main view contains a two column grid, with the first column filled with a listbox whose datatemplate consists of a usercontrol and the second column filled with another usercontrol. These two usercontrols have the same datacontext. MainView: <Grid> //Column defs ... <ListView Grid.Column="0" ItemSource="{Binding Foo}"> ... <DataTemplate> <Views: FooView1 /> </DataTemplate> </ListView> <TextBlock Text="{Binding Foo.Count}" /> <StackPanel Grid.Column="1"> <Views: FooView2 /> </StackPanel> <Grid> FooView1: <UserControl> <TextBlock Text="{Binding Foo.Title}"> </UserControl> FooView2: <UserControl> <TextBlock Text="{Binding Foo.Detail1}"> <TextBlock Text="{Binding Foo.Detail2}"> <TextBlock Text="{Binding Foo.Detail3}"> <TextBlock Text="{Binding Foo.Detail4}"> </UserControl> I've no IDE here. Excuse me if there is any syntax error When the user clicks on a button. These two usercontrols have to be replaced by another two usercontrols, so the datacontext changes, the main ui remaining the same. ie, FooView1 by BarView1 and FooView2 by BarView2 In short i want to bind this view changes in mainview to my command (command from Button) How can i do this? Also tell me if i could merge the usercontrol pairs, so that only one view exists for each viewmodel ie, FooView1 and FooView2 into FooView and so on...

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  • Boost program will not working on Linux

    - by Martin Lauridsen
    Hi SOF, I have this program which uses Boost::Asio for sockets. I pretty much altered some code from the Boost examples. The program compiles and runs just like it should on Windows in VS. However, when I compile the program on Linux and run it, I get a Segmentation fault. I posted the code here The command I use to compile it is this: c++ -I/appl/htopopt/Linux_x86_64/NTL-5.4.2/include -I/appl/htopopt/Linux_x86_64/boost_1_43_0/include mpqs.cpp mpqs_polynomial.cpp mpqs_host.cpp -o mpqs_host -L/appl/htopopt/Linux_x86_64/NTL-5.4.2/lib -lntl -L/appl/htopopt/Linux_x86_64/gmp-4.2.1/lib -lgmp -lm -L/appl/htopopt/Linux_x86_64/boost_1_43_0/lib -lboost_system -lboost_thread -static -lpthread By commenting out code, I have found out that I get the Segmentation fault due to the following line: boost::asio::io_service io_service; Can anyone provide any assistance, as to what may be the problem (and the solution)? Thanks! Edit: I tried changing the program to a minimal example, using no other libraries or headers, just boost/asio.hpp: #define DEBUG 0 #include <boost/asio.hpp> int main(int argc, char* argv[]) { boost::asio::io_service io_service; return 0; } I also removed other library inclusions and linking on compilation, however this minimal example still gives me a segmentation fault.

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  • Generic Constraints And Type Parameters Mess

    - by Dummy01
    Hi everyone, I have the following base abstract class defined as: public abstract class BaseObject<T> : IComparable, IComparable<T>, IEquatable<T> {} I also have an interface defined as: public interface ICode<T> where T : struct { T Code { get; } } Now I want to derive a class that is inherited from BaseObject<T> and includes interface ICode<T>. I tried to define it like that: public class DerivedObject<T, U> : BaseObject<T>, ICode<U> where T : DerivedObject<T, U> where U : struct { public DerivedObject(U code) { Code = code; } // From BaseObject protected override int InstanceCompareTo(T obj) { return Code.CompareTo(obj.Code); } // From BaseObject protected override bool InstanceEquals(T obj) { return Code.Equals(obj.Code); } // From ICode U _Code; public U Code { get { return _Code; } protected set { _Code = value; } } } The only error that comes from the compiler is for Code.CompareTo(obj.Code) with the message: 'U' does not contain a definition for 'CompareTo' and no extension method 'CompareTo' accepting a first argument of type 'U' could be found. But U is a value type and should know CompareTo. Have you any idea what I am doing wrong, or if I do all wrong? My final aim is to derive classes such these: public class Account : DerivedObject<Account, int> public class ItemGroup : DerivedObject<ItemGroup, string> Big Thanks In Advance!

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  • push(ing)_back objects pointers within a loop

    - by Jose Manuel Albornoz
    Consider the following: I have a class CDevices containing, amongst others, a string member class CDevice { public: CDevice(void); ~CDevice(void); // device name std::string Device_Name; etc... } and somewhere else in my code I define another class that contains a vector of pointers to CDevices class CDevice; class CServers { public: CServers(void); ~CServers(void); // Devices vector vector<CDevice*> Devices; etc... } The problem appears in the following lines in my main.c pDevice = new CDevice; pDevice->Device_Name = "de"; Devices.push_back(pDevice); pDevice->Device_Name = " revolotiunibus"; Devices.push_back(pDevice); pDevice->Device_Name = " orbium"; Devices.push_back(pDevice); pDevice->Device_Name = " coelestium"; Devices.push_back(pDevice); for(int i = 0; i < (int)Devices.size(); ++i) cout << "\nLoad name = " << Devices.at(i)->Device_Name << endl; The output I get is " coelestium" repeated four times: each time I push_back a new element into the vector all of the already existing elements take the value of the one which has just been added. I have also tried using iterators to recover each element in the vector with the same results. Could someone please tell me what's wrong here? Thankx

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  • Using an initializer_list on a map of vectors

    - by Hooked
    I've been trying to initialize a map of <ints, vector<ints> > using the new 0X standard, but I cannot seem to get the syntax correct. I'd like to make a map with a single entry with key:value = 1:<3,4 #include <initializer_list> #include <map> #include <vector> using namespace std; map<int, vector<int> > A = {1,{3,4}}; .... It dies with the following error using gcc 4.4.3: error: no matching function for call to std::map<int,std::vector<int,std::allocator<int> >,std::less<int>,std::allocator<std::pair<const int,std::vector<int,std::allocator<int> > > > >::map(<brace-enclosed initializer list>) Edit Following the suggestion by Cogwheel and adding the extra brace it now compiles with a warning that can be gotten rid of using the -fno-deduce-init-list flag. Is there any danger in doing so?

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  • Catch hibernate exceptions with errorpage handler?

    - by membersound
    I'm catching all exceptions within: java.lang.Throwable /page.xhtml java.lang.Error /page.xhtml But what If I get eg a hibernate ex: org.hibernate.exception.ConstraintViolationException Do I have to define error-pages for EVERY maybe occuring exception? Can't I just say "catch every exception"? Update Redirect on a 404 works. But on a throwable does not! <servlet> <servlet-name>Faces Servlet</servlet-name> <servlet-class>javax.faces.webapp.FacesServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>Faces Servlet</servlet-name> <url-pattern>*.jsf</url-pattern> <url-pattern>*.xhtml</url-pattern> </servlet-mapping> <error-page> <exception-type>java.lang.Throwable</exception-type> <location>/error.xhtml</location> </error-page> <error-page> <error-code>404</error-code> <location>/error.xhtml</location> </error-page>

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  • Faster quadrature decoder loops with Python code

    - by Kelei
    I'm working with a BeagleBone Black and using Adafruit's IO Python library. Wrote a simple quadrature decoding function and it works perfectly fine when the motor runs at about 1800 RPM. But when the motor runs at higher speeds, the code starts missing some of the interrupts and the encoder counts start to accumulate errors. Do you guys have any suggestions as to how I can make the code more efficient or if there are functions which can cycle the interrupts at a higher frequency. Thanks, Kel Here's the code: # Define encoder count function def encodercount(term): global counts global Encoder_A global Encoder_A_old global Encoder_B global Encoder_B_old global error Encoder_A = GPIO.input('P8_7') # stores the value of the encoders at time of interrupt Encoder_B = GPIO.input('P8_8') if Encoder_A == Encoder_A_old and Encoder_B == Encoder_B_old: # this will be an error error += 1 print 'Error count is %s' %error elif (Encoder_A == 1 and Encoder_B_old == 0) or (Encoder_A == 0 and Encoder_B_old == 1): # this will be clockwise rotation counts += 1 print 'Encoder count is %s' %counts print 'AB is %s %s' % (Encoder_A, Encoder_B) elif (Encoder_A == 1 and Encoder_B_old == 1) or (Encoder_A == 0 and Encoder_B_old == 0): # this will be counter-clockwise rotation counts -= 1 print 'Encoder count is %s' %counts print 'AB is %s %s' % (Encoder_A, Encoder_B) else: #this will be an error as well error += 1 print 'Error count is %s' %error Encoder_A_old = Encoder_A # store the current encoder values as old values to be used as comparison in the next loop Encoder_B_old = Encoder_B # Initialize the interrupts - these trigger on the both the rising and falling GPIO.add_event_detect('P8_7', GPIO.BOTH, callback = encodercount) # Encoder A GPIO.add_event_detect('P8_8', GPIO.BOTH, callback = encodercount) # Encoder B # This is the part of the code which runs normally in the background while True: time.sleep(1)

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  • How can I concisely copy multiple SQL rows, with minor modifications?

    - by Steve Jessop
    I'm copying a subset of some data, so that the copy will be independently modifiable in future. One of my SQL statements looks something like this (I've changed table and column names): INSERT Product( ProductRangeID, Name, Weight, Price, Color, And, So, On ) SELECT @newrangeid AS ProductRangeID, Name, Weight, Price, Color, And, So, On FROM Product WHERE ProductRangeID = @oldrangeid and Color = 'Blue' That is, we're launching a new product range which initially just consists of all the blue items in some specified current range, under new SKUs. In future we may change the "blue-range" versions of the products independently of the old ones. I'm pretty new at SQL: is there something clever I should do to avoid listing all those columns, or at least avoid listing them twice? I can live with the current code, but I'd rather not have to come back and modify it if new columns are added to Product. In its current form it would just silently fail to copy the new column if I forget to do that, which should show up in testing but isn't great. I am copying every column except for the ProductRangeID (which I modify), the ProductID (incrementing primary key) and two DateCreated and timestamp columns (which take their auto-generated values for the new row). Btw, I suspect I should probably have a separate join table between ProductID and ProductRangeID. I didn't define the tables. This is in a T-SQL stored procedure on SQL Server 2008, if that makes any difference.

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  • java web templates across multiple WAR files

    - by Casey
    I have a multi WAR web application that was designed badly. There is a single WAR that is responsible for handling some authorization against a database and defines a standard web page using a jsp taglib. The main WAR basically checks the privileges of the user and than based on that, displays links to the context path of the other deployed WARS. Each of the other deployed WARs includes this custom tag lib. I am working on redesigning this application, and one of the nice things that I want to retain is that we have other project teams that have developed these WAR modules that "plug into" our current system to take advantage of other things we have to offer. I am not entirely sure how to handle the page templates though. I need a templating system that would be easy enough to use across multiple wars (I was thinking of jsp fragments??). I really only need to define a consistent header and main navigation section. Whatever else is displayed on the page is up to the individual web project. Any suggestions? I hope that this is clear, if not I can elaborate more.

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  • Parsing CSS by regex

    - by Ross
    I'm creating a CSS editor and am trying to create a regular expression that can get data from a CSS document. This regex works if I have one property but I can't get it to work for all properties. I'm using preg/perl syntax in PHP. Regex (?<selector>[A-Za-z]+[\s]*)[\s]*{[\s]*((?<properties>[A-Za-z0-9-_]+)[\s]*:[\s]*(?<values>[A-Za-z0-9#, ]+);[\s]*)*[\s]*} Test case body { background: #f00; font: 12px Arial; } Expected Outcome Array( [0] => Array( [0] => body { background: #f00; font: 12px Arial; } [selector] => Array( [0] => body ) [1] => Array( [0] => body ) [2] => font: 12px Arial; [properties] => Array( [0] => font ) [3] => Array( [0] => font ) [values] => Array( [0] => 12px Arial [1] => background: #f00 ) [4] => Array( [0] => 12px Arial [1] => background: #f00 ) ) ) Real Outcome Array( [0] => Array ( [0] => body { background: #f00; font: 12px Arial; } [selector] => body [1] => body [2] => font: 12px Arial; [properties] => font [3] => font [values] => 12px Arial [4] => 12px Arial ) ) Thanks in advance for any help - this has been confusing me all afternoon!

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