Search Results

Search found 8397 results on 336 pages for 'implementation'.

Page 261/336 | < Previous Page | 257 258 259 260 261 262 263 264 265 266 267 268  | Next Page >

• What is a good automated data import method for SQL Server?

  - by Joel Potter

  I'm in the process of porting some SQL Server 2005 databases to SQL Server 2008. One of these databases has an associated import application (Windows task) which uses SSIS with a DTS package to import a large dataset from an MS Access database nightly. In upgrading to SQL Server 2008, I discovered that I can't run the same console application which has been performing the imports due to the missing manageddts DLL in SQL Server 2008. It's several years old and in need of a rewrite for various reason, plus, I've been fairly unhappy with DTS in general. The original reason DTS was chosen was for speed (5 min import time compared to 30+ for ADO.NET). The format of the data to import is out of my control (the client likes Access). I would also like to be able to run the import from a machine completely separate from the server hosting SQL Server and preferably with minimal SQL features installed. Options I've considered: Creating an Access application to connect to both databases (SQL Server and Access) and perform the import (Ugh!) Revisiting ADO.NET to see if the original implementation was poorly written. Updated SSIS packages. What other technologies should I be considering for this job?

  Read the article

• Drupal module permissions

  - by Trevor Newhook

  When I run the code with an admin user, the module returns what it should. However, when I run it with a normal user, I get a 403 error. The module returns data from an AJAX call. I've already tried adding a 'access callback' = 'user_access'); line to the exoticlang_chat_logger_menu() function. I'd appreciate any pointers you might have. Thanks for the help The AJAX call: jQuery.ajax({ type: 'POST', url: '/chatlog', success: exoticlangAjaxCompleted, data:'messageLog=' + privateMessageLogJson, dataType: 'json' }); The module code: function exoticlang_chat_logger_init(){ drupal_add_js('misc/jquery.form.js'); drupal_add_library('system', 'drupal.ajax'); } function exoticlang_chat_logger_permission() { return array( 'Save chat data' => array( 'title' => t('Save ExoticLang Chat Data'), 'description' => t('Send private message on chat close') ), ); } /** * Implementation of hook_menu(). */ function exoticlang_chat_logger_menu() { $items = array(); $items['chatlog'] = array( 'type' => MENU_CALLBACK, 'page callback' => 'exoticlang_chat_log_ajax', 'access arguments' => 'Save chat data'); //'access callback' => 'user_access'); return $items; } function exoticlang_chat_logger_ajax(){ $messageLog=stripslashes($_POST['messageLog']); $chatLog= 'Drupal has processed this. Message log is: '.$messageLog; $chatLog=str_replace('":"{[{','":[{',$chatLog); $chatLog=str_replace(',,',',',$chatLog); $chatLog=str_replace('"}"','"}',$chatLog); $chatLog=str_replace('"}]}"','"}]',$chatLog); echo json_encode(array('messageLog' => $chatLog)); // echo $chatLog; echo print_r(privatemsg_new_thread(array(user_load(1)), 'The subject', 'The body text')); drupal_exit(); }

  Read the article

• Object Oriented Perl interface to read from and write to a socket

  - by user654967

  I need a perl client-server implementation as a wrapper for a server in C#. A perl script passes the server address and port number and an input string to a module, this module has to create the socket and send the input string to the server. The data sent has to follow ISO-8859-1 encoding. On receiving the information, the client has to first receive 3 byte, then the next 8 bytes, this has the length of the data that has to be received next.. so based on the length the client has to read the next data. each of the data that is read has to be stored in a variable and sent another module for further processing. Currently this is what my perl client looks like..which I'm sure isn't right..could someone tell me how to do this..and set me on the right direction.. sub WriteInfo { my ($addr, $port, $Input) = @_; $socket = IO::Socket::INET->new( Proto => "tcp", PeerAddr => $addr, PeerPort => $port, ); unless ($socket) { die "cannot connect to remote" } while (1) { $socket->send($Input); } } sub ReadData { while (1) { my $ExecutionResult = $socket->recv( $recv_data, 3); my $DataLength = $socket->recv( $recv_data, 8); $DataLength =~ s/^0+// ; my $decval = hex($DataLength); my $Data = $socket->recv( $recv_data, $decval); return($Data); } thanks a lot.. Archer

  Read the article

• How to benchmark on multi-core processors

  - by Pascal Cuoq

  I am looking for ways to perform micro-benchmarks on multi-core processors. Context: At about the same time desktop processors introduced out-of-order execution that made performance hard to predict, they, perhaps not coincidentally, also introduced special instructions to get very precise timings. Example of these instructions are rdtsc on x86 and rftb on PowerPC. These instructions gave timings that were more precise than could ever be allowed by a system call, allowed programmers to micro-benchmark their hearts out, for better or for worse. On a yet more modern processor with several cores, some of which sleep some of the time, the counters are not synchronized between cores. We are told that rdtsc is no longer safe to use for benchmarking, but I must have been dozing off when we were explained the alternative solutions. Question: Some systems may save and restore the performance counter and provide an API call to read the proper sum. If you know what this call is for any operating system, please let us know in an answer. Some systems may allow to turn off cores, leaving only one running. I know Mac OS X Leopard does when the right Preference Pane is installed from the Developers Tools. Do you think that this make rdtsc safe to use again? More context: Please assume I know what I am doing when trying to do a micro-benchmark. If you are of the opinion that if an optimization's gains cannot be measured by timing the whole application, it's not worth optimizing, I agree with you, but I cannot time the whole application until the alternative data structure is finished, which will take a long time. In fact, if the micro-benchmark were not promising, I could decide to give up on the implementation now; I need figures to provide in a publication whose deadline I have no control over.

  Read the article

• Main Function Error C++

  - by Arjun Nayini

  I have this main function: #ifndef MAIN_CPP #define MAIN_CPP #include "dsets.h" using namespace std; int main(){ DisjointSets s; s.uptree.addelements(4); for(int i=0; i<s.uptree.size(); i++) cout <<uptree.at(i) << endl; return 0; } #endif And the following class: class DisjointSets { public: void addelements(int x); int find(int x); void setunion(int x, int y); private: vector<int> uptree; }; #endif My implementation is this: void DisjointSets::addelements(int x){ for(int i=0; i<x; i++) uptree.push_back(-1); } //Given an int this function finds the root associated with that node. int DisjointSets::find(int x){ //need path compression if(uptree.at(x) < 0) return x; else return find(uptree.at(x)); } //This function reorders the uptree in order to represent the union of two //subtrees void DisjointSets::setunion(int x, int y){ } Upon compiling main.cpp (g++ main.cpp) I'm getting these errors: dsets.h: In function \u2018int main()\u2019: dsets.h:25: error: \u2018std::vector DisjointSets::uptree\u2019 is private main.cpp:9: error: within this context main.cpp:9: error: \u2018class std::vector \u2019 has no member named \u2018addelements\u2019 dsets.h:25: error: \u2018std::vector DisjointSets::uptree\u2019 is private main.cpp:10: error: within this context main.cpp:11: error: \u2018uptree\u2019 was not declared in this scope I'm not sure exactly whats wrong. Any help would be appreciated.

  Read the article

• Fastest Java way to remove the first/top line of a file (like a stack)

  - by christangrant

  I am trying to improve an external sort implementation in java. I have a bunch of BufferedReader objects open for temporary files. I repeatedly remove the top line from each of these files. This pushes the limits of the Java's Heap. I would like a more scalable method of doing this without loosing speed because of a bunch of constructor calls. One solution is to only open files when they are needed, then read the first line and then delete it. But I am afraid that this will be significantly slower. So using Java libraries what is the most efficient method of doing this. --Edit-- For external sort, the usual method is to break a large file up into several chunk files. Sort each of the chunks. And then treat the sorted files like buffers, pop the top item from each file, the smallest of all those is the global minimum. Then continue until for all items. http://en.wikipedia.org/wiki/External_sorting My temporary files (buffers) are basically BufferedReader objects. The operations performed on these files are the same as stack/queue operations (peek and pop, no push needed). I am trying to make these peek and pop operations more efficient. This is because using many BufferedReader objects takes up too much space.

  Read the article

• Online file storage similar to Amazon S3

  - by Joel G

  I am looking to code a file storage application in perl similar to amazon s3. I already have a amazon s3 clone that I found online called parkplace but its in ruby and is old also isn't built for high loads. I am not really sure what modules and programs I should use so id like some help picking them out. My requirements are listed below (yes I know there are lots but I could start simple then add more once I get it going): Easy API implementation for client side apps. (maybe RESTful but extras like mkdir and cp (?) Centralized database server for the USERDB (maybe PostgreSQL (?). Logging of all connections, bandwidth used, well pretty much everything to a centralized server (maybe PostgreSQL again (?). Easy server side configuration (config file(s) stored on the servers). Web based control panel for admin(s) and user(s) to show logs. (could work just running queries from the databases) Fast High Uptime Low memory usage Some sort of load distribution/load balancer (maybe a dns based or pound or perlbal or something else (?). Maybe a cache of some sort (memcached or parlbal or something else (?). Thanks in advance

  Read the article

• Xerces C++ SAX Parsing Problem: expected class-name before '{' token

  - by aduric

  I'm trying to run through an example given for the C++ Xerces XML library implementation. I've copied the code exactly, but I'm having trouble compiling it. error: expected class-name before '{' token I've looked around for a solution, and I know that this error can be caused by circular includes or not defining a class before it is used, but as you can see from the code, I only have 2 files: MySAXHandler.hpp and MySAXHandler.cpp. However, the MySAXHandler class is derived from HandlerBase, which is included. MyHandler.hpp #include <xercesc/sax/HandlerBase.hpp> class MySAXHandler : public HandlerBase { public: void startElement(const XMLCh* const, AttributeList&); void fatalError(const SAXParseException&); }; MySAXHandler.cpp #include "MySAXHandler.hpp" #include <iostream> using namespace std; MySAXHandler::MySAXHandler() { } void MySAXHandler::startElement(const XMLCh* const name, AttributeList& attributes) { char* message = XMLString::transcode(name); cout << "I saw element: "<< message << endl; XMLString::release(&message); } void MySAXHandler::fatalError(const SAXParseException& exception) { char* message = XMLString::transcode(exception.getMessage()); cout << "Fatal Error: " << message << " at line: " << exception.getLineNumber() << endl; XMLString::release(&message); } I'm compiling like so: g++ -L/usr/local/lib -lxerces-c -I/usr/local/include -c MySAXHandler.cpp I've looked through the HandlerBase and it is defined, so I don't know why I can't derive a class from it? Do I have to override all the virtual functions in HandlerBase? I'm kinda new to C++. Thanks in advance.

  Read the article

• DotNetOpenAuth / WebSecurity Basic Info Exchange

  - by Jammer

  I've gotten a good number of OAuth logins working on my site now. My implementation is based on the WebSecurity classes with amends to the code to suit my needs (I pulled the WebSecurity source into mine). However I'm now facing a new set of problems. In my application I have opted to make the user email address the login identifier of choice. It's naturally unique and suits this use case. However, the OAuth "standards" strikes again. Some providers will return your email address as "username" (Google) some will return the display name (Facebook). As it stands I see to options given my particular scenario: Option 1 Pull even more framework source code into my solution until I can chase down where the OpenIdRelyingParty class is actually interacted with (via the DotNetOpenAuth.AspNet facade) and make addition information requests from the OpenID Providers. Option 2 When a user first logs in using an OpenID provider I can display a kind of "complete registration" form that requests missing info based on the provider selected.* Option 2 is the most immediate and probably the quickest to implement but also includes some code smells through having to do something different based on the provider selected. Option 1 will take longer but will ultimately make things more future proof. I will need to perform richer interactions down the line so this also has an edge in that regard. The more I get into the code it does seem that the WebSecurity class itself is actually very limiting as it hides lots of useful DotNetOpenAuth functionality in the name of making integration easier. Andrew (the author of DNOA) has said that the Attribute Exchange stuff happens in the OpenIdRelyingParty class but I cannot see from the DotNetOpenAuth.AspNet source code where this class is used so I'm unsure of what source would need to be pulled into my code in order to enable the functionality I need. Has anyone completely something similar?

  Read the article

• How to move from custom to transluscent NavigationBar and back? Display problems!

  - by jd291

  So, i got this Navigation-based App (with a custom NavigationBar - Category) and I have 2 problems here... @implementation UINavigationBar (Custom) - (void)drawRect:(CGRect)rect { UIImage *image = [UIImage imageNamed: @"bg_toolbar.png"]; [image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)]; } @end Because of the Navigation-based App, most of the views have a height of 436px (= ScreenSize - NavigationBar height, as you probably know ;). I got one view similar to the photo app overview showing all the thumbnails, from there I push a viewcontroller containing the scroll view (like in photos app) on the stack, like so - (void)buttonPressed:(id)sender { UIButton *btn = (UIButton *)sender; PhotoSetScrollViewController *psc = [[PhotoSetScrollViewController alloc] initWithPhotoArray:photos andID:btn.tag]; [self.navigationController pushViewController:psc animated:YES]; } Problem 1: The view holding the fullscreen scrollview has a height of 480px which seems to be a problem because when poping the viewcontroller by hitting the back button, the view containing the thumbnails (height 436px) moves upward below the navigation bar. And also the Toolbar keeps showing. What could be the problem? Problem 2: How could I switch between my custom navigation bar and the standard black translucent style?

  Read the article

• Recursive QuickSort suffering a StackOverflowException -- Need fresh eyes

  - by jon

  I am working on a Recursive QuickSort method implementation in a GenericList Class. I will have a second method that accepts a compareDelegate to compare different types, but for development purposes I'm sorting a GenericList<int I am recieving stackoverflow areas in different places depending on the list size. I've been staring at and tracing through this code for hours and probably just need a fresh pair of (more experienced)eyes. Definitely wanting to learn why it is broken, not just how to fix it. public void QuickSort() { int i, j, lowPos, highPos, pivot; GenericList<T> leftList = new GenericList<T>(); GenericList<T> rightList = new GenericList<T>(); GenericList<T> tempList = new GenericList<T>(); lowPos = 1; highPos = this.Count; if (lowPos < highPos) { pivot = (lowPos + highPos) / 2; for (i = 1; i <= highPos; i++) { if (this[i].CompareTo(this[pivot]) <= 0) leftList.Add(this[i]); else rightList.Add(this[i]); } leftList.QuickSort(); rightList.QuickSort(); for(i=1;i<=leftList.Count;i++) tempList.Add(leftList[i]); for(i=1;i<=rightList.Count;i++) tempList.Add(rightList[i]); this.items = tempList.items; this.count = tempList.count; } }

  Read the article

• How can I simply change a class variable from another class in ObjectiveC?

  - by Daniel

  I simply want to change a variable of an object from another class. I can compile without a problem, but my variable always is set to 'null'. I used the following code: Object.h: @interface Object : NSObject { //... NSString *color; //... } @property(nonatomic, retain) NSString* color; + (id)Object; - (void)setColor:(NSString*)col; - (NSString*)getColor; @end Object.m: +(id)Object{ return [[[Object alloc] init] autorelease]; } - (void)setColor:(NSString*)col { self.color = col; } - (NSString*)getColor { return self.color; } MyViewController.h #import "Object.h" @interface ClassesTestViewController : UIViewController { Object *myObject; UILabel *label1; } @property UILabel *label1; @property (assign) Object *myObject; @end MyViewController.m: #import "Object.h" @implementation MyViewController @synthesize myObject; - (void)viewDidLoad { [myObject setColor:@"red"]; NSLog(@"Color = %@", [myObject getColor]); [super viewDidLoad]; } The NSLog message is always Color = (null) I tried many different ways to solve this problem, but no success. Any help would be appreciated.

  Read the article

• Warning: cast increases required alignment

  - by dash-tom-bang

  I'm recently working on this platform for which a legacy codebase issues a large number of "cast increases required alignment to N" warnings, where N is the size of the target of the cast. struct Message { int32_t id; int32_t type; int8_t data[16]; }; int32_t GetMessageInt(const Message& m) { return *reinterpret_cast<int32_t*>(&data[0]); } Hopefully it's obvious that a "real" implementation would be a bit more complex, but the basic point is that I've got data coming from somewhere, I know that it's aligned (because I need the id and type to be aligned), and yet I get the message that the cast is increasing the alignment, in the example case, to 4. Now I know that I can suppress the warning with an argument to the compiler, and I know that I can cast the bit inside the parentheses to void* first, but I don't really want to go through every bit of code that needs this sort of manipulation (there's a lot because we load a lot of data off of disk, and that data comes in as char buffers so that we can easily pointer-advance), but can anyone give me any other thoughts on this problem? I mean, to me it seems like such an important and common option that you wouldn't want to warn, and if there is actually the possibility of doing it wrong then suppressing the warning isn't going to help. Finally, can't the compiler know as I do how the object in question is actually aligned in the structure, so it should be able to not worry about the alignment on that particular object unless it got bumped a byte or two?

  Read the article

• Naive Bayesian classification (spam filtering) - Doubt in one calculation? Which one is right? Plz c

  - by Microkernel

  Hi guys, I am implementing Naive Bayesian classifier for spam filtering. I have doubt on some calculation. Please clarify me what to do. Here is my question. In this method, you have to calculate P(S|W) - Probability that Message is spam given word W occurs in it. P(W|S) - Probability that word W occurs in a spam message. P(W|H) - Probability that word W occurs in a Ham message. So to calculate P(W|S), should I do (1) (Number of times W occuring in spam)/(total number of times W occurs in all the messages) OR (2) (Number of times word W occurs in Spam)/(Total number of words in the spam message) So, to calculate P(W|S), should I do (1) or (2)? (I thought it to be (2), but I am not sure, so plz clarify me) I am refering http://en.wikipedia.org/wiki/Bayesian_spam_filtering for the info by the way. I got to complete the implementation by this weekend :( Thanks and regards, MicroKernel :) @sth: Hmm... Shouldn't repeated occurrence of word 'W' increase a message's spam score? In the your approach it wouldn't, right?. Lets take a scenario and discuss... Lets say, we have 100 training messages, out of which 50 are spam and 50 are Ham. and say word_count of each message = 100. And lets say, in spam messages word W occurs 5 times in each message and word W occurs 1 time in Ham message. So total number of times W occuring in all the spam message = 5*50 = 250 times. And total number of times W occuring in all Ham messages = 1*50 = 50 times. Total occurance of W in all of the training messages = (250+50) = 300 times. So, in this scenario, how do u calculate P(W|S) and P(W|H) ? Naturally we should expect, P(W|S) P(W|H)??? right. Please share your thought...

  Read the article

• Credit Card storage solution

  - by jtnire

  Hi Everyone, I'm developing a solution that is designed to store membership details, as well as credit card details. I'm trying to comply with PCI DSS as much as I can. Here is my design so far: PAN = Primary account number == long number on credit card Server A is a remote server. It stores all membership details (Names, Address etc..) and provides indivudal Key A's for each PAN stored Server B is a local server, and actually holds the encrypted PANs, as well as Key B, and does the decryption. To get a PAN, the client has to authenticate with BOTH servers, ask Server A for the respective Key A, then give Key A to server B, which will return the PAN to the client (provided authentication was sucessful). Server A will only ever encrypt Key A with Server B's public Key, as it will have it beforehand. Server B will probably have to send a salt first though, however I doin't think that has to be encrypted I havn't really thought about any implementation (i.e. coding) specifics yet regarding the above, however the solution is using Java's Cajo framework (wrapper for RMI) so that is how the servers will communicate with each other (Currently, membership details are transfered in this way). The reason why I want Server B to do the decryption, and not the client, is that I am afraid of decryption keys going into the client's RAM, even though it's probably just as bad on the server... Can anyone see anything wrong with the above design? It doesn't matter if the above has to be changed. Thanks jtnire

  Read the article

• NSTimer as a timeout mechanism

  - by alexantd

  I'm pretty sure this is really simple, and I'm just missing something obvious. I have an app that needs to download data from a web service for display in a UITableView, and I want to display a UIAlertView if the operation takes more than X seconds to complete. So this is what I've got (simplified for brevity): MyViewController.h @interface MyViewController : UIViewController <UITableViewDelegate, UITableViewDataSource> { NSTimer *timer; } @property (nonatomic, retain) NSTimer *timer; MyViewController.m @implementation MyViewController @synthesize timer; - (void)viewDidLoad { timer = [NSTimer scheduledTimerWithTimeInterval:20 target:self selector:@selector(initializationTimedOut:) userInfo:nil repeats:NO]; [self doSomethingThatTakesALongTime]; [timer invalidate]; } - (void)doSomethingThatTakesALongTime { sleep(30); // for testing only // web service calls etc. go here } - (void)initializationTimedOut:(NSTimer *)theTimer { // show the alert view } My problem is that I'm expecting the [self doSomethingThatTakesALongTime] call to block while the timer keeps counting, and I'm thinking that if it finishes before the timer is done counting down, it will return control of the thread to viewDidLoad where [timer invalidate] will proceed to cancel the timer. Obviously my understanding of how timers/threads work is flawed here because the way the code is written, the timer never goes off. However, if I remove the [timer invalidate], it does.

  Read the article

• Visual Studio - Edit source code located in a database

  - by mfeingold

  I am building something similar to Server Explorer for Apache CouchDB. One of the things necessary is to be able to edit CouchDB view definitions which in CouchDB are JavaScript functions. How can I trick Visual Studio into using my object to retrieve and save the content of the JavaScript function but still use the rest of it - I am happy with editor itself and have no intention of writing my own Editor/Language Service, etc. The latter would be much bigger effort than what this project warrants Edit After more digging I am still stuck. Here is what I know: IVsUIShellOpenDocument interface provides a method OpenStandardEditor which can be used to open the standard Visual Studio editor. As one of the parameters this method takes a Pointer to the IUnknown interface of the document data object. This object is supposed to implement several interfaces described in many places all over the MSDN. Visual Studio SDK also provides a 'sample' implementation of the document data object VsTextBufferClass. I can create an instance of this class and when I pass the pointer to the instance to the OpenStandardEditor I can see my editor and it seems to work ok. When I try to implement my own class implementing the same interfaces (IVsTextBuffer, VsTextBuffer, IVsTextLines) OpenStandardEditor method returns success, but VS bombs out on call editor.Show() with an access violation. My suspicion is that VsTextBufferClass also implements some other interface(s) but not in C# way but rather in the good old COM way. I just do not know which one(s). Any thoughts?

  Read the article

• Bulletin board - Database optimisation

  - by andrew

  This question is a follow on from this Question The project and problem The project I am currently working on is a bulletin board for a large non-profit organisation. The bulletin board will be used to allow inter-office communication within the organisation. I am building the application and have been having trouble extracting the results that I need from my database because I don't think it is properly normalized and because of limitations in my knowledge of relational database theory and mysql. I would appreciate input into the design of the board in general and in particular, ways that the database structure can be improved to facilitate efficient queries and help me develop this application and future application faster Business Logic The bulletin board will be used in the following way Posting bulletins and responses to bulletins Employees or 'users' in offices around the country will be able to post messages to the bulletin board.Bulletins must be posted to a location and categorised- i'll call these "bulletins". Users will be able to post any number of replies to any one bulletin and users will be able to reply to their own bulletin - i'll call these 'replies'. Rating bulletins and replies Users will be able to either 'like' or 'dislike' a bulletin or a reply and the total number of likes or dislikes will be shown for each bulletin or reply. Viewing the bulletin board and responses Bulletins can be displayed chronologically. Users can sort bulletins chronologically or chronologically by the latest reply to that bulletin(let me know if you need more explanation) When a particular bulletin is selected, replies to that bulletin will be displayed chronologically @PerformanceDBA - edited 10:34 est 28/12/10I have begun implementing the data model. I assume that the 6th data model is the physical model because it contains the associative tables. I am going to post any questions that I have below. I will put up a database dump once I am done. I will then put up a list of all the queries that I need to run on the database and begin writing them. I hope you had a good Christmas. I'm in Canada and there's snow! Implementation of Physical model

  Read the article

• C++: parsing with simple regular expression or shoud I use sscanf?

  - by Helltone

  I need to parse a string like func1(arg1, arg2); func2(arg3, arg4);. It's not a very complex parsing problem, so I would prefer to avoid resorting to flex/bison or similar utilities. My first approch was to try to use POSIX C regcomp/regexec or Boost implementation of C++ std::regex. I wrote the following regular expression, which does not work (I'll explain why further on). "^" "[ ;\t\n]*" "(" // (1) identifier "[a-zA-Z_][a-zA-Z0-9_]*" ")" "[ \t\n]*" "(" // (2) non-marking "\[" "(" // (3) non-marking "[ \t]*" "(" // (4..n-1) argument "[a-zA-Z0-9_]+" ")" "[ \t\n]*" "," ")*" "[ \t\n]*" "(" // (n) last argument "[a-zA-Z0-9_]+" ")" "]" ")?" "[ \t\n]*" ";" Note that the group 1 captures the identifier and groups 4..n-1 are intended to capture arguments except the last, which is captured by group n. When I apply this regex to, say func(arg1, arg2, arg3) the result I get is an array {func, arg2, arg3}. This is wrong because arg1 is not in it! The problem is that in the standard regex libraries, submarkings only capture the last match. In other words, if you have for instance the regex "((a*|b*))*" applied on "babb", the results of the inner match will be bb and all previous captures will have been forgotten. Another thing that annoys me here is that in case of error there is no way to know which character was not recognized as these functions provide very little information about the state of the parser when the input is rejected. So I don't know if I'm missing something here... In this case should I use sscanf or similar instead? Note that I prefer to use C/C++ standard libraries (and maybe boost).

  Read the article

• Help me write my LISP :) LISP environments, Ruby Hashes...

  - by MikeC8

  I'm implementing a rudimentary version of LISP in Ruby just in order to familiarize myself with some concepts. I'm basing my implementation off of Peter Norvig's Lispy (http://norvig.com/lispy.html). There's something I'm missing here though, and I'd appreciate some help... He subclasses Python's dict as follows: class Env(dict): "An environment: a dict of {'var':val} pairs, with an outer Env." def __init__(self, parms=(), args=(), outer=None): self.update(zip(parms,args)) self.outer = outer def find(self, var): "Find the innermost Env where var appears." return self if var in self else self.outer.find(var) He then goes on to explain why he does this rather than just using a dict. However, for some reason, his explanation keeps passing in through my eyes and out through the back of my head. Why not use a dict, and then inside the eval function, when a new "sub-environment" needs to be created, just take the existing dict and update the key/value pairs that need to be updated, and pass that new dict into the next eval? Won't the Python interpreter keep track of the previous "outer" envs? And won't the nature of the recursion ensure that the values are pulled out from "inner" to "outer"? I'm using Ruby, and I tried to implement things this way. Something's not working though, and it might be because of this, or perhaps not. Here's my eval function, env being a regular Hash: def eval(x, env = $global_env) ........ elsif x[0] == "lambda" then ->(*args) { eval(x[2], env.merge(Hash[*x[1].zip(args).flatten(1)])) } ........ end The line that matters of course is the "lambda" one. If there is a difference, what's importantly different between what I'm doing here and what Norvig did with his Env class? If there's no difference, then perhaps someone can enlighten me as to why Norvig uses the Env class. Thanks :)

  Read the article

• How to find an embedded platform?

  - by gmagana

  I am new to the locating hardware side of embedded programming and so after being completely overwhelmed with all the choices out there (pc104, custom boards, a zillion option for each board, volume discounts, devel kits, ahhh!!) I am asking here for some direction. Basically, I must find a new motherboard and (most likely) re-implement the program logic. Rewriting this in C/C++/Java/C#/Pascal/BASIC is not a problem for me. so my real problem is finding the hardware. This motherboard will have several other devices attached to it. Here is a summary of what I need to do: Required: 2 RS232 serial ports (one used all the time for primary UI, the second one not continuous) 1 modem (9600+ baud ok) [Modem will be in simultaneous use with only one of the serial port devices, so interrupt sharing with one serial port is OK, but not both] Minimum permanent/long term storage: Whatever O/S requires + 1 MB (executable) + 512 KB (Data files) RAM: Minimal, whatever the O/S requires plus maybe 1MB for executable. Nice to have: USB port(s) Ethernet network port Wireless network Implementation languages (any O/S I will adapt to): First choice Java/C# (Mono ok) Second choice is C/Pascal Third is BASIC Ok, given all this, I am having a lot of trouble finding hardware that will support this that is low in cost. Every manufacturer site I visit has a lot of options, and it's difficult to see if their offering will even satisfy my must-have requirements (for example they sometimes list 3 "serial ports", but it appears that only one of the three is RS232, for example, and don't mention what the other two are). The #1 constraint is cost, #2 is size. Can anyone help me with this? This little task has left me thinking I should have gone for EE and not CS :-). EDIT: A bit of background: This is a system currently in production, but the original programmer passed away, and the current hardware manufacturer cannot find hardware to run the (currently) DOS system, so I need to reimplement this in a modern platform. I can only change the programming and the motherboard hardware.

  Read the article

• How do I optimize this postfix expression tree for speed?

  - by Peter Stewart

  Thanks to the help I received in this post: I have a nice, concise recursive function to traverse a tree in postfix order: deque <char*> d; void Node::postfix() { if (left != __nullptr) { left->postfix(); } if (right != __nullptr) { right->postfix(); } d.push_front(cargo); return; }; This is an expression tree. The branch nodes are operators randomly selected from an array, and the leaf nodes are values or the variable 'x', also randomly selected from an array. char *values[10]={"1.0","2.0","3.0","4.0","5.0","6.0","7.0","8.0","9.0","x"}; char *ops[4]={"+","-","*","/"}; As this will be called billions of times during a run of the genetic algorithm of which it is a part, I'd like to optimize it for speed. I have a number of questions on this topic which I will ask in separate postings. The first is: how can I get access to each 'cargo' as it is found. That is: instead of pushing 'cargo' onto a deque, and then processing the deque to get the value, I'd like to start processing it right away. I don't yet know about parallel processing in c++, but this would ideally be done concurrently on two different processors. In python, I'd make the function a generator and access succeeding 'cargo's using .next(). But I'm using c++ to speed up the python implementation. I'm thinking that this kind of tree has been around for a long time, and somebody has probably optimized it already. Any Ideas? Thanks

  Read the article

• Any merit to a lazy-ish juxt function?

  - by NielsK

  In answering a question about a function that maps over multiple functions with the same arguments (A: juxt), I came up with a function that basically took the same form as juxt, but used map: (defn could-be-lazy-juxt [& funs] (fn [& args] (map #(apply %1 %2) funs (repeat args)))) => ((juxt inc dec str) 1) [2 0 "1"] => ((could-be-lazy-juxt inc dec str) 1) (2 0 "1") => ((juxt * / -) 6 2) [12 3 4] => ((could-be-lazy-juxt * / -) 6 2) (12 3 4) As posted in the original question, I have little clue about the laziness or performance of it, but timing in the REPL does suggest something lazy-ish is going on. => (time (apply (juxt + -) (range 1 100))) "Elapsed time: 0.097198 msecs" [4950 -4948] => (time (apply (could-be-lazy-juxt + -) (range 1 100))) "Elapsed time: 0.074558 msecs" (4950 -4948) => (time (apply (juxt + -) (range 10000000))) "Elapsed time: 1019.317913 msecs" [49999995000000 -49999995000000] => (time (apply (could-be-lazy-juxt + -) (range 10000000))) "Elapsed time: 0.070332 msecs" (49999995000000 -49999995000000) I'm sure this function is not really that quick (the print of the outcome 'feels' about as long in both). Doing a 'take x' on the function only limits the amount of functions evaluated, which probably is limited in it's applicability, and limiting the other parameters by 'take' should be just as lazy in normal juxt. Is this juxt really lazy ? Would a lazy juxt bring anything useful to the table, for instance as a compositing step between other lazy functions ? What are the performance (mem / cpu / object count / compilation) implications ? Is that why the Clojure juxt implementation is done with a reduce and returns a vector ? Edit: Somehow things can always be done simpler in Clojure. (defn could-be-lazy-juxt [& funs] (fn [& args] (map #(apply % args) funs)))

  Read the article

• Mercurial repository usage with binary files for building setup files

  - by Ryan

  I have an existing Mercurial repository for a C++ application in a small corporate environment. I asked a co-worker to add the setup script to the repository and he added all of the dependency binaries, PDFs, and executable to the repository under an Install directory. I dislike having the binaries and dependencies in the same repository, but I'd like recommendations on best practices. Here are the options I am considering: Create a separate repository for the Installer and related files Create a subrepository for the Installer and related files Use a (yet to be identified) build dependency manager I am concerned with using a subrepository with Mercurial based on what I've read so far and the (apparently) incomplete implementation. I would like to get a project dependency system, e.g. Ivy, but I don't know all of the options and haven't had time yet to try out any options. I thought I'd use TortoiseHg as a basis, and it does not have the TortoiseHg binaries in the repository although it does have some binaries such as kdiff3.exe. Instead it uses setup.py to clone multiple repositories and build the apps. This seems reasonable for OSS, but not so much for corporate environments. Recommendations?

  Read the article

• Circular dependency with generics

  - by devoured elysium

  I have defined the following interface: public interface IStateSpace<State, Action> where State : IState where Action : IAction<State, Action> // <-- this is the line that bothers me { void SetValueAt(State state, Action action); Action GetValueAt(State state); } Basically, an IStateSpace interface should be something like a chess board, and in each position of the chess board you have a set of possible movements to do. Those movements here are called IActions. I have defined this interface this way so I can accommodate for different implementations: I can then define concrete classes that implement 2D matrix, 3D matrix, graphs, etc. public interface IAction<State, Action> { IStateSpace<State, Action> StateSpace { get; } } An IAction, would be to move up(this is, if in (2, 2) move to (2, 1)), move down, etc. Now, I'll want that each action has access to a StateSpace so it can do some checking logic. Is this implementation correct? Or is this a bad case of a circular dependence? If yes, how to accomplish "the same" in a different way? Thanks

  Read the article

< Previous Page | 257 258 259 260 261 262 263 264 265 266 267 268  | Next Page >