Search Results

Search found 5521 results on 221 pages for 'deeper understanding'.

Page 209/221 | < Previous Page | 205 206 207 208 209 210 211 212 213 214 215 216  | Next Page >

• Hierarchy inheritance

  - by reito

  I had faced the problem. In my C++ hierarchy tree I have two branches for entities of difference nature, but same behavior - same interface. I created such hierarchy trees (first in image below). And now I want to work with Item or Base classes independetly of their nature (first or second). Then I create one abstract branch for this use. My mind build (second in image below). But it not working. Working scheme seems (third in image below). It's bad logic, I think... Do anybody have some ideas about such hierarchy inheritance? How make it more logical? More simple for understanding? Image Sorry for my english - russian internet didn't help:) Update: You ask me to be more explicit, and I will be. In my project (plugins for Adobe Framemaker) I need to work with dialogs and GUI controls. In some places I working with WinAPI controls, and some other places with FDK (internal Framemaker) controls, but I want to work throw same interface. I can't use one base class and inherite others from it, because all needed controls - is a hierarchy tree (not one class). So I have one hierarchy tree for WinAPI controls, one for FDK and one abstract tree to use anyone control. For example, there is an Edit control (WinEdit and FdkEdit realization), a Button control (WinButton and FdkButton realization) and base entity - Control (WinControl and FdkControl realization). For now I can link my classes in realization trees (Win and Fdk) with inheritence between each of them (WinControl is base class for WinButton and WinEdit; FdkControl is base class for FdkButton and FdkEdit). And I can link to abstract classes (Control is base class for WinControl and FdkControl; Edit is base class for WinEdit and FdkEdit; Button is base class for WinButton and FdkButton). But I can't link my abstract tree - compiler swears. In fact I have two hierarchy trees, that I want to inherite from another one. Update: I have done this quest! :) I used the virtual inheritence and get such scheme (http://img12.imageshack.us/img12/7782/99614779.png). Abstract tree has only absolute abstract methods. All inheritence in abstract tree are virtual. Link from realization tree to abstract are virtual. On image shown only one realization tree for simplicity. Thanks for help!

  Read the article

• Permanent mutex locking causing deadlock?

  - by Daniel

  I am having a problem with mutexes (pthread_mutex on Linux) where if a thread locks a mutex right again after unlocking it, another thread is not very successful getting a lock. I've attached test code where one mutex is created, along with two threads that in an endless loop lock the mutex, sleep for a while and unlock it again. The output I expect to see is "alive" messages from both threads, one from each (e.g. 121212121212. However what I get is that one threads gets the majority of locks (e.g. 111111222222222111111111 or just 1111111111111...). If I add a usleep(1) after the unlocking, everything works as expected. Apparently when the thread goes to SLEEP the other thread gets its lock - however this is not the way I was expecting it, as the other thread has already called pthread_mutex_lock. I suspect this is the way this is implemented, in that the actice thread has priority, however it causes certain problem in this particular testcase. Is there any way to prevent it (short of adding a deliberately large enough delay or some kind of signaling) or where is my error in understanding? #include <pthread.h> #include <stdio.h> #include <string.h> #include <sys/time.h> #include <unistd.h> pthread_mutex_t mutex; void* threadFunction(void *id) { int count=0; while(true) { pthread_mutex_lock(&mutex); usleep(50*1000); pthread_mutex_unlock(&mutex); // usleep(1); ++count; if (count % 10 == 0) { printf("Thread %d alive\n", *(int*)id); count = 0; } } return 0; } int main() { // create one mutex pthread_mutexattr_t attr; pthread_mutexattr_init(&attr); pthread_mutex_init(&mutex, &attr); // create two threads pthread_t thread1; pthread_t thread2; pthread_attr_t attributes; pthread_attr_init(&attributes); int id1 = 1, id2 = 2; pthread_create(&thread1, &attributes, &threadFunction, &id1); pthread_create(&thread2, &attributes, &threadFunction, &id2); pthread_attr_destroy(&attributes); sleep(1000); return 0; }

  Read the article

• Hibernate3: Self-Referencing Objects

  - by monojohnny

  Need some help on understanding how to do this; I'm going to be running recursive 'find' on a file system and I want to keep the information in a single DB table - with a self-referencing hierarchial structure: This is my DB Table structure I want to populate. DirObject Table: id int NOT NULL, name varchar(255) NOT NULL, parentid int NOT NULL); Here is the proposed Java Class I want to map (Fields only shown): public DirObject { int id; String name; DirObject parent; ... For the 'root' directory was going to use parentid=0; real ids will start at 1, and ideally I want hibernate to autogenerate the ids. Can somebody provide a suggested mapping file for this please; as a secondary question I thought about doing the Java Class like this instead: public DirObject { int id; String name; List<DirObject> subdirs; Could I use the same data model for either of these two methods ? (With a different mapping file of course). --- UPDATE: so I tried the mapping file suggested below (thanks!), repeated here for reference: <hibernate-mapping> <class name="my.proj.DirObject" table="category"> ... <set name="subDirs" lazy="true" inverse="true"> <key column="parentId"/> <one-to-many class="my.proj.DirObject"/> </set> <many-to-one name="parent" class="my.proj.DirObject" column="parentId" cascade="all" /> </class> ...and altered my Java class to have BOTH 'parentid' and 'getSubDirs' [returning a 'HashSet']. This appears to work - thanks, but this is the test code I used to drive this - I think I'm not doing something right here, because I thought Hibernate would take care of saving the subordinate objects in the Set without me having to do this explicitly ? DirObject dirobject=new DirObject(); dirobject.setName("/files"); dirobject.setParent(dirobject); DirObject d1, d2; d1=new DirObject(); d1.setName("subdir1"); d1.setParent(dirobject); d2=new DirObject(); d2.setName("subdir2"); d2.setParent(dirobject); HashSet<DirObject> subdirs=new HashSet<DirObject>(); subdirs.add(d1); subdirs.add(d2); dirobject.setSubdirs(subdirs); session.save(dirobject); session.save(d1); session.save(d2);

  Read the article

• remove data layer and put into it's own domain

  - by user334768

  I have a SL4 application that uses EF4 & RIA Services. DB is SQL 2008. All is working well. Now I want to put the Database and web services on one domain (A.com) with the web service exposing the same methods available in my working project. (one listed at top of message) Then put a Silverlight application (same one as above) on domain(B.com) and call the web services on A.com. I thought I had a fair understanding of RIA Services. Enough to get the above application working. Now when I say "working" I do mean on my local dev machine. I have yet to deployed as SL4 & .NET 4 application to my hosting site. But I don't think I understand it well enough. I normally create a new business app, add EF then create the RIA DomainService. Add any [Includes] I need, modify my linq queries and run application. And it works. Now I need to break off my data layer and put it on another hosting site (A.com) And put my UI and business logic on another hosting site (B.com) I think I need to do the following : On the Database & web service site: domain(A.com) create application, create EF4, create RIA Services and deploy. At this time, are the methods exposed available as a "WEB SERVICE" to other applications calling by http:// a.com/serviceName.svc address? I think I need to do the following : On the application site : domain(B.com) create a business application (later will need authentication and navigation). How can I create an EF when I don't have access to the database? (I know I do have access but I want know what happens here when I do not have access to the database, but only data provided by a web service) If I can not create an EF how do I create my RIA Service? I hope any one who takes time to help me understands what I'm asking. Sorry so long.

  Read the article

• how to use window.onload?

  - by Patrick

  I'm refactoring a website using MVC. What was a set of huge pages with javascript, php, html etc etc is becoming a series of controllers and views. I'm trying to do it in a modular way so views are split in 'modules' that I can reuse in other pages when needed eg. "view/searchform displays only one div with the searchform "view/display_events displays a list of events and so on. One of the old pages was supposed to load a google map with a marker on it. Amongst the rest of the code, I can identify the relevant bits as follows <head> <script src="http://maps.google.com/maps?file=api&amp;v=2&amp;key=blablabla" type="text/javascript"></script> <script type="text/javascript"> //<![CDATA[ function load() { if (GBrowserIsCompatible()) { var map = new GMap2(document.getElementById("map")); var point = new GLatLng(<?php echo ($info->lat && $info->lng) ? $info->lat .",". $info->lng : "51.502759,-0.126171"; ?>); map.setCenter(new GLatLng(<?php echo ($info->lat && $info->lng) ? $info->lat .",". $info->lng : "51.502759,-0.126171"; ?>), 15); map.addControl(new GLargeMapControl()); map.addControl(new GScaleControl()); map.addOverlay(new GMarker(point)); var marker = createMarker(point,GIcon(),"CIAO"); map.addOverlay(marker); } } //]]> </script> </head> ...then <body onload="load()" onunload="GUnload()"> ...and finally this div where the map should be displayed <div id="map" style="width: 440px; height: 300px"> </div> Don't know much about js, but my understanding is that a) I have to include the scripts in the view module I'm writing (directly in the HTML? I would prefer to load a separate script) b) I have to trigger that function using the equivalent of body onload... (obviously there's no body tag in my view. In my ignorance I've tried div onload=.... but didn't seem to be working :) What do you suggest I do? I've read about window.onload but don't know what's the correct syntax for that. please keep in mind that other parts of the page include other js functions (eg, google adsense) that are called after the footer.

  Read the article

• basic operations for modifying a source document with XSLT

  - by SpliFF

  All the tutorials and examples I've found of XSLT processing seem to assume your destination will be a significantly different format/structure to your source and that you know the structure of the source in advance. I'm struggling with finding out how to perform simple "in-place" modifications to a HTML document without knowing anything else about its existing structure. Could somebody show me a clear example that, given an arbitrary unknown HTML source will: 1.) delete the classname 'foo' from all divs 2.) delete a node if its empty (ie <p></p>) 3.) delete a <p> node if its first child is <br> 4.) add newattr="newvalue" to all H1 5.) replace 'heading' in text nodes with 'title' 6.) wrap all <u> tags in <b> tags (ie, <u>foo</u> -> <b><u>foo</u></b>) 7.) output the transformed document without changing anything else The above examples are the primary types of transform I wish to accomplish. Understanding how to do the above will go a long way towards helping me build more complex transforms. To help clarify/test the examples here is a sample source and output, however I must reiterate that I want to work with arbitrary samples without rewriting the XSLT for each source: <!doctype html> <html> <body> <h1>heading</h1> <p></p> <p><br>line</p> <div class="foo bar"><u>baz</u></div> <p>untouched</p> </body> </html> output: <!doctype html> <html> <body> <h1 newattr="newvalue">title</h1> <div class="bar"><b><u>baz</u></b></div> <p>untouched</p> </body> </html>

  Read the article

• What is an overloaded operator in c++?

  - by Jeff

  I realize this is a basic question but I have searched online, been to cplusplus.com, read through my book, and I can't seem to grasp the concept of overloaded operators. A specific example from cplusplus.com is: // vectors: overloading operators example #include <iostream> using namespace std; class CVector { public: int x,y; CVector () {}; CVector (int,int); CVector operator + (CVector); }; CVector::CVector (int a, int b) { x = a; y = b; } CVector CVector::operator+ (CVector param) { CVector temp; temp.x = x + param.x; temp.y = y + param.y; return (temp); } int main () { CVector a (3,1); CVector b (1,2); CVector c; c = a + b; cout << c.x << "," << c.y; return 0; } from http://www.cplusplus.com/doc/tutorial/classes2/ but reading through it I'm still not understanding them at all. I just need a basic example of the point of the overloaded operator (which I assume is the "CVector CVector::operator+ (CVector param)"). There's also this example from wikipedia: Time operator+(const Time& lhs, const Time& rhs) { Time temp = lhs; temp.seconds += rhs.seconds; if (temp.seconds >= 60) { temp.seconds -= 60; temp.minutes++; } temp.minutes += rhs.minutes; if (temp.minutes >= 60) { temp.minutes -= 60; temp.hours++; } temp.hours += rhs.hours; return temp; } from "http://en.wikipedia.org/wiki/Operator_overloading" The current assignment I'm working on I need to overload a ++ and a -- operator. Thanks in advance for the information and sorry about the somewhat vague question, unfortunately I'm just not sure on it at all.

  Read the article

• Javascript self contained sandbox events and client side stack

  - by amnon

  I'm in the process of moving a JSF heavy web application to a REST and mainly JS module application . I've watched "scalable javascript application architecture" by Nicholas Zakas on yui theater (excellent video) and implemented much of the talk with good success but i have some questions : I found the lecture a little confusing in regards to the relationship between modules and sandboxes , on one had to my understanding modules should not be effected by something happening outside of their sandbox and this is why they publish events via the sandbox (and not via the core as they do access the core for hiding base libary) but each module in the application gets a new sandbox ? , shouldn't the sandbox limit events to the modoules using it ? or should events be published cross page ? e.g. : if i have two editable tables but i want to contain each one in a different sandbox and it's events effect only the modules inside that sandbox something like messabe box per table which is a different module/widget how can i do that with sandbox per module , ofcourse i can prefix the events with the moduleid but that creates coupling that i want to avoid ... and i don't want to package modules toghter as one module per combination as i already have 6-7 modules ? while i can hide the base library for small things like id selector etc.. i would still like to use the base library for module dependencies and resource loading and use something like yui loader or dojo.require so in fact i'm hiding the base library but the modules themself are defined and loaded by the base library ... seems a little strange to me libraries don't return simple js objects but usualy wrap them e.g. : u can do something like $$('.classname').each(.. which cleans the code alot , it makes no sense to wrap the base and then in the module create a dependency for the base library by executing .each but not using those features makes a lot of code written which can be left out ... and implemnting that functionality is very bug prone does anyonen have any experience with building a front side stack of this order ? how easy is it to change a base library and/or have modules from different libraries , using yui datatable but doing form validation with dojo ... ? some what of a combination of 2+4 if u choose to do something like i said and load dojo form validation widgets for inputs via yui loader would that mean dojocore is a module and the form module is dependant on it ? Thanks .

  Read the article

• Java DriverManager Always Assigns My Driver

  - by JGB146

  I am writing a driver to act as a wrapper around two separate MySQL connections (to distributed databases). Basically, the goal is to enable interaction with my driver for all applications instead of requiring the application to sort out which database holds the desired data. Most of the code for this is in place, but I'm having a problem in that when I attempt to create connections via the MySQL Driver, the DriverManager is returning an instance of my driver instead of the MySQL Driver. I'd appreciate any tips on what could be causing this and what could be done to fix it! Below is a few relevant snippets of code. I can provide more, but there's a lot, so I'd need to know what else you want to see. First, from MyDriver.java: public MyDriver() throws SQLException { DriverManager.registerDriver(this); } public Connection connect(String url, Properties info) throws SQLException { try { return new MyConnection(info); } catch (Exception e) { return null; } } public boolean acceptsURL(String url) throws SQLException { if (url.contains("jdbc:jgb://")) { return true; } return false; } It is my understanding that this acceptsURL function will dictate whether or not the DriverManager deems my driver a suitable fit for a given URL. Hence it should only be passing connections from my driver if the URL contains "jdbc:jgb://" right? Here's code from MyConnection.java: Connection c1 = null; Connection c2 = null; /** *Constructors */ public DDBSConnection (Properties info) throws SQLException, Exception { info.list(System.out); //included for testing Class.forName("com.mysql.jdbc.Driver").newInstance(); String url1 = "jdbc:mysql://server1.com/jgb"; String url2 = "jdbc:mysql://server2.com/jgb"; this.c1 = DriverManager.getConnection( url1, info.getProperty("username"), info.getProperty("password")); this.c2 = DriverManager.getConnection( url2, info.getProperty("username"), info.getProperty("password")); } And this tells me two things. First, the info.list() call confirms that the correct user and password are being sent. Second, because we enter an infinite loop, we see that the DriverManager is providing new instances of my connection as matches for the mysql URLs instead of the desired mysql driver/connection. FWIW, I have separately tested implementations that go straight to the mysql driver using this exact syntax (al beit only one at a time), and was able to successfully interact with each database individually from a test application outside of my driver.

  Read the article

• Dynamically loading modules in Python (+ threading question)

  - by morpheous

  I am writing a Python package which reads the list of modules (along with ancillary data) from a configuration file. I then want to iterate through each of the dynamically loaded modules and invoke a do_work() function in it which will spawn a new thread, so that the code runs in a separate thread. At the moment, I am importing the list of all known modules at the beginning of my main script - this is a nasty hack I feel, and is not very flexible, as well as being a maintenance pain. This is the function that spawns the threads. I will like to modify it to dynamically load the module when it is encountered. The key in the dictionary is the name of the module containing the code: def do_work(work_info): for (worker, dataset) in work_info.items(): #import the module defined by variable worker here... t = threading.Thread(target=worker.do_work, args=[dataset]) # I'll NOT dameonize since spawned children need to clean up on shutdown # Since the threads will be holding resources #t.daemon = True t.start() Question 1 When I call the function in my script (as written above), I get the following error: AttributeError: 'str' object has no attribute 'do_work' Which makes sense, since the dictionary key is a string (name of the module to be imported). When I add the statement: import worker before spawning the thread, I get the error: ImportError: No module named worker This is strange, since the variable name rather than the value it holds are being used - when I print the variable, I get the value (as I expect) whats going on? Question 2 As I mentioned in the comments section, I realize that the do_work() function written in the spawned children needs to cleanup after itself. My understanding is to write a clean_up function that is called when do_work() has completed successfully, or an unhandled exception is caught - is there anything more I need to do to ensure resources don't leak or leave the OS in an unstable state? Question 3 If I comment out the t.daemon flag statement, will the code stil run ASYNCHRONOUSLY?. The work carried out by the spawned children are pretty intensive, and I don't want to have to be waiting for one child to finish before spawning another child. BTW, I am aware that threading in Python is in reality, a kind of time sharing/slicing - thats ok Lastly is there a better (more Pythonic) way of doing what I'm trying to do?

  Read the article

• Is it possible to use CSS to align these divs/spans in a table-like manner?

  - by Justin L.

  I have <div class='line'> <div class='chord_line'> <span class='chord_block'></span> <span class='chord_block'>E</span> <span class='chord_block'>B</span> <span class='chord_block'>C#m</span> <span class='chord_block'>A</span> </div> <div class='lyric_line'> <span class='lyric_block'></span> <span class='lyric_block'>Just a</span> <span class='lyric_block'>small-town girl</span> <span class='lyric_block'>living in a</span> <span class='lyric_block'>lonely world</span> </div> </div> (Excuse me for not being too familiar with proper css conventions for when to use div/spans) I want to be able to display them so that each chord_block span and lyric_block span is aligned vertically, as if they were left-aligned and on the same row of a table. For example: E B C#m A Just a small-town girl living in a lonely world (There will often be cases where an empty chord block is matched up to non-empty lyric block, and vice-versa.) I'm completely new to using CSS to align things, and have had no real understanding/experience of CSS aside from changing background colors and link styles. Is this possible in CSS? If not, how could the div/class nesting structure be revised to make this possible? I could change the spans to divs if necessary. Some things I cannot use: I can't change the structure to group things by a chord_and_lyric_block div (and have their width stretch to the length of the lyric, and stack them horizontally), because I couldn't really copy/select the lyrical lines continuously in their entirety, which is extremely critical. I'm trying to avoid a table-like solution, because this data is not tabular at all. The chord line and the lyric line are meant to be read as one continuous line, not a set of cells. Also, apart from the design philosophy reasons, I think it might have the same problems as the previous thing bullet point. If this is possible, what div/span attributes should I be using? Can you provide sample css? If this is not possible, can it be done with javascript?

  Read the article

• Which is the "best" data access framework/approach for C# and .NET?

  - by Frans

  (EDIT: I made it a community wiki as it is more suited to a collaborative format.) There are a plethora of ways to access SQL Server and other databases from .NET. All have their pros and cons and it will never be a simple question of which is "best" - the answer will always be "it depends". However, I am looking for a comparison at a high level of the different approaches and frameworks in the context of different levels of systems. For example, I would imagine that for a quick-and-dirty Web 2.0 application the answer would be very different from an in-house Enterprise-level CRUD application. I am aware that there are numerous questions on Stack Overflow dealing with subsets of this question, but I think it would be useful to try to build a summary comparison. I will endeavour to update the question with corrections and clarifications as we go. So far, this is my understanding at a high level - but I am sure it is wrong... I am primarily focusing on the Microsoft approaches to keep this focused. ADO.NET Entity Framework Database agnostic Good because it allows swapping backends in and out Bad because it can hit performance and database vendors are not too happy about it Seems to be MS's preferred route for the future Complicated to learn (though, see 267357) It is accessed through LINQ to Entities so provides ORM, thus allowing abstraction in your code LINQ to SQL Uncertain future (see Is LINQ to SQL truly dead?) Easy to learn (?) Only works with MS SQL Server See also Pros and cons of LINQ "Standard" ADO.NET No ORM No abstraction so you are back to "roll your own" and play with dynamically generated SQL Direct access, allows potentially better performance This ties in to the age-old debate of whether to focus on objects or relational data, to which the answer of course is "it depends on where the bulk of the work is" and since that is an unanswerable question hopefully we don't have to go in to that too much. IMHO, if your application is primarily manipulating large amounts of data, it does not make sense to abstract it too much into objects in the front-end code, you are better off using stored procedures and dynamic SQL to do as much of the work as possible on the back-end. Whereas, if you primarily have user interaction which causes database interaction at the level of tens or hundreds of rows then ORM makes complete sense. So, I guess my argument for good old-fashioned ADO.NET would be in the case where you manipulate and modify large datasets, in which case you will benefit from the direct access to the backend. Another case, of course, is where you have to access a legacy database that is already guarded by stored procedures. ASP.NET Data Source Controls Are these something altogether different or just a layer over standard ADO.NET? - Would you really use these if you had a DAL or if you implemented LINQ or Entities? NHibernate Seems to be a very powerful and powerful ORM? Open source Some other relevant links; NHibernate or LINQ to SQL Entity Framework vs LINQ to SQL

  Read the article

• C++ SQLDriverConnect API

  - by harshalkreddy

  Hi, I am using visual studio 2008 and sql server 2008 for developing application(SQL server is in my system). I need to fetch some fields from the database. I am using the SQLDriverConnect API to connect to the database. If I use the "SQL_DRIVER_PROMPT" I will get pop window to select the data source. I don't want this window to appear. As per my understanding this window will appear if we provide insufficient information in the connection string. I think I have provided all the information. I am trying to connect with windows authentication. I tried different options but still no luck. Please help me in solving this problem. Below is the code that I am using: //******************************************************************************** // SQLDriverConnect_ref.cpp // compile with: odbc32.lib user32.lib #include <windows.h> #include <sqlext.h> int main() { SQLHENV henv; SQLHDBC hdbc; SQLHSTMT hstmt; SQLRETURN retcode; SQLWCHAR OutConnStr[255]; SQLSMALLINT OutConnStrLen; SQLCHAR ConnStrIn[255] = "DRIVER={SQL Server};SERVER=(local);DSN=MyDSN;DATABASE=MyDatabase;Trusted_Connection=yes;"; //SQLWCHAR *ConntStr =(SQLWCHAR *) "DRIVER={SQL Server};DSN=MyDSN;"; HWND desktopHandle = GetDesktopWindow(); // desktop's window handle // Allocate environment handle retcode = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv); // Set the ODBC version environment attribute if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) { retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER*)SQL_OV_ODBC3, 0); // Allocate connection handle if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) { retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc); // Set login timeout to 5 seconds if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) { SQLSetConnectAttr(hdbc, SQL_LOGIN_TIMEOUT, (SQLPOINTER)5, 0); retcode = SQLDriverConnect( // SQL_NULL_HDBC hdbc, desktopHandle, (SQLWCHAR *)ConnStrIn, SQL_NTS, OutConnStr, 255, &OutConnStrLen, SQL_DRIVER_NOPROMPT); // Allocate statement handle if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) { retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt); // Process data if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) { SQLFreeHandle(SQL_HANDLE_STMT, hstmt); } SQLDisconnect(hdbc); } SQLFreeHandle(SQL_HANDLE_DBC, hdbc); } } SQLFreeHandle(SQL_HANDLE_ENV, henv); } } //******************************************************************************** Thanks in advance, Harsha

  Read the article

• Java: file write on finalize method

  - by sowrov

  In my understanding a singleton object will destroy only when the application is about to terminate. So in C++ I write a Singleton class to log my application and in that Singleton logger's destructor I log the time when my application was terminated. Things worked perfectly in C++. Now I want to have that same logger in Java, as in java there is no destructor so I implemented the finalize method for that singleton logger. But it seem that finalize method actually never get called. So, I add that System.runFinalizersOnExit(true); line, somewhere in my code (though I know it is deprecated) and that finalize method get called every time before termination of the app. But still there is a problem! If I try to write anything on file in that finalize method, It does not work, though System.out work without any problem! :( Can you guys help me on this problem? Here is a sample code of what I am try to do: Singleton Logger Class: public class MyLogger { FileWriter writer; private MyLogger() { try { this.writer = new FileWriter("log.txt"); } catch (IOException ex) { } } public static MyLogger getInstance() { return MyLoggerHolder.INSTANCE; } private static class MyLoggerHolder { private static final MyLogger INSTANCE = new MyLogger(); } @Override protected void finalize () { try { super.finalize(); System.out.println("Here"); //worked correctly. this.writer.write(new Date().toString()+System.getProperty("line.separator")); this.writer.write("End"); this.writer.flush(); //does not work! this.writer.close(); } catch (Throwable ex) { } } public synchronized void log(String str) { try { this.writer.write(new Date().toString()+System.getProperty("line.separator")); this.writer.write(str+"\n"); this.writer.flush(); } catch (IOException ex) { } } } Main: public class Main { public static void main(String[] args) { System.runFinalizersOnExit(true); MyLogger logger = MyLogger.getInstance(); logger.log("test"); } }

  Read the article

• JPanels, JFrames, and Windows, Oh my!

  - by Jonathan

  Simply stated, I am trying to make a game I am working on full-screen. I have the following code I am trying to use: GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment(); GraphicsDevice gs = ge.getDefaultScreenDevice(); if(!gs.isFullScreenSupported()) { System.out.println("full-screen not supported"); } Frame frame = new Frame(gs.getDefaultConfiguration()); Window win = new Window(frame); try { // Enter full-screen mode gs.setFullScreenWindow(win); win.validate(); } Problem with this is that I am working within a class that extends JPanel, and while I have a variable of type Frame, I have none of type Window within the class. My understanding of JPanel is that it is a Window of sorts, but I cannot pass 'this' into gs.setFullScreenWindow(Window win)... How should I go about doing this? Is there any easy way of calling that, or a similar method, using a JPanel? Is there a way I can get something of type Window from my JPanel? - EDIT: The following method changes the state of JFrame and is called every 10ms: public void paintScreen() { Graphics g; try{ g = this.getGraphics(); //get Panel's graphic context if(g == null) { frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setExtendedState(frame.getExtendedState()|JFrame.MAXIMIZED_BOTH); frame.add(this); frame.pack(); frame.setResizable(false); frame.setTitle("Game Window"); frame.setVisible(true); } if((g != null) && (dbImage != null)) { g.drawImage(dbImage, 0, 0, null); } Toolkit.getDefaultToolkit().sync(); //sync the display on some systems g.dispose(); } catch (Exception e) { if(blockError) { blockError = false; } else { System.out.println("Graphics context error: " + e); } } } I anticipate that there may be a few redundancies or unnecessary calls after the if(g==null) statement (all the frame.somethingOrOther()s), any cleanup advice would be appreciated... Also, the block error is what it seems. I am ignoring an error. The error only occurs once, and this works fine when setup to ignore the first instance of the error... For anyone interested I can post additional info there if anyone wants to see if that block can be removed, but i'm not concerned... I might look into it later.

  Read the article

• What's special about mouse capture and middle mouse button in WPF?

  - by Scott Bilas

  When I call CaptureMouse() in response to a MouseDown from the middle mouse button, it will capture and then release the mouse. Huh? I've tried using Preview events, setting Handled=true, doesn't make a difference. Am I not understanding mouse capture in WPF? Here's some minimal sample code that reproduces the problem. // TestListBox.cs using System.Diagnostics; using System.Windows.Controls; namespace Local { public class TestListBox : ListBox { public TestListBox() { MouseDown += (_, e) => { Debug.WriteLine("+MouseDown"); Debug.WriteLine(" Capture: " + CaptureMouse()); Debug.WriteLine("-MouseDown"); }; MouseUp += (_, e) => { Debug.WriteLine("+MouseUp"); ReleaseMouseCapture(); Debug.WriteLine("-MouseUp"); }; GotMouseCapture += (_, e) => Debug.WriteLine("GotMouseCapture"); LostMouseCapture += (_, e) => Debug.WriteLine("LostMouseCapture"); } } } Generating a default WPF app that has this for its main window will use the test class: <Window x:Class="Local.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:Local" Title="MainWindow" Height="350" Width="525"> <local:TestListBox> <ListBoxItem>1</ListBoxItem> <ListBoxItem>2</ListBoxItem> <ListBoxItem>3</ListBoxItem> <ListBoxItem>4</ListBoxItem> </local:TestListBox> </Window> Upon clicking the middle button down, I get this output: +MouseDown GotMouseCapture LostMouseCapture Capture: True -MouseDown So I'm calling CaptureMouse, which in turn grabs and then releases capture, yet returns true that capture was successfully acquired. What's going on here? Is it possible that this is something with my Logitech mouse driver doing something goofy, trying to initiate 'ultrascroll' or something?

  Read the article

• How to create a database deadlock using jdbc and JUNIT

  - by Isawpalmetto

  I am trying to create a database deadlock and I am using JUnit. I have two concurrent tests running which are both updating the same row in a table over and over again in a loop. My idea is that you update say row A in Table A and then row B in Table B over and over again in one test. Then at the same time you update row B table B and then row A Table A over and over again. From my understanding this should eventually result in a deadlock. Here is the code For the first test. public static void testEditCC() { try{ int rows = 0; int counter = 0; int large=10000000; Connection c=DataBase.getConnection(); while(counter<large) { int pid = 87855; int cCode = 655; String newCountry="Egypt"; int bpl = 0; stmt = c.createStatement(); rows = stmt.executeUpdate("UPDATE main " + //create lock on main table "SET BPL="+cCode+ "WHERE ID="+pid); rows = stmt.executeUpdate("UPDATE BPL SET DESCRIPTION='SomeWhere' WHERE ID=602"); //create lock on bpl table counter++; } assertTrue(rows == 1); //rows = stmt.executeUpdate("Insert into BPL (ID, DESCRIPTION) VALUES ("+cCode+", '"+newCountry+"')"); } catch(SQLException ex) { ex.printStackTrace(); //ex.getMessage(); } } And here is the code for the second test. public static void testEditCC() { try{ int rows = 0; int counter = 0; int large=10000000; Connection c=DataBase.getConnection(); while(counter<large) { int pid = 87855; int cCode = 655; String newCountry="Jordan"; int bpl = 0; stmt = c.createStatement(); //stmt.close(); rows = stmt.executeUpdate("UPDATE BPL SET DESCRIPTION='SomeWhere' WHERE ID=602"); //create lock on bpl table rows = stmt.executeUpdate("UPDATE main " + //create lock on main table "SET BPL="+cCode+ "WHERE ID="+pid); counter++; } assertTrue(rows == 1); //rows = stmt.executeUpdate("Insert into BPL (ID, DESCRIPTION) VALUES ("+cCode+", '"+newCountry+"')"); } catch(SQLException ex) { ex.printStackTrace(); } } I am running these two separate JUnit tests at the same time and am connecting to an apache Derby database that I am running in network mode within Eclipse. Can anyone help me figure out why a deadlock is not occurring? Perhaps I am using JUnit wrong.

  Read the article

• HTML5 - Need explanation about outline

  - by RhymeGuy

  So, lets say that I have the following structure: <doctype html> <header> <h1>Header</h1> <article><h2>Article</h2></article> <article><h2>Article</h2></article> </header> <main> <h1>Main content</h1> <article><h2>Article</h2></article> <article><h2>Article</h2></article> <article><h2>Article</h2></article> <article><h2>Article</h2></article> </main> <section> <h1>Sidebar</h1> </section> If i check outline using http://gsnedders.html5.org/outliner/ (or any other), I'll get outline like this: 1. Main content 1. Header 1. Article 2. Article 2. Article 3. Article 4. Article 5. Article 6. Sidebar Which (from my understanding) is not correct. I have thought that it should look like this: 1. Header 1. Article 2. Article 2. Main content 1. Article 2. Article 3. Article 4. Article 3. Sidebar Why this happens? I can get desired outline if I use section element. But id there is main element in HTML structure, then everything breaks (at least for me - it's not how I understood it). Can I achieve desired outline using main element?

  Read the article

• How do I write object classes effectively when dealing with table joins?

  - by Chris

  I should start by saying I'm not now, nor do I have any delusions I'll ever be a professional programmer so most of my skills have been learned from experience very much as a hobby. I learned PHP as it seemed a good simple introduction in certain areas and it allowed me to design simple web applications. When I learned about objects, classes etc the tutor's basic examnples covered the idea that as a rule of thumb each database table should have its own class. While that worked well for the photo gallery project we wrote, as it had very simple mysql queries, it's not working so well now my projects are getting more complex. If I require data from two separate tables which require a table join I've instead been ignoring the class altogether and handling it on a case by case basis, OR, even worse been combining some of the data into the class and the rest as a separate entity and doing two queries, which to me seems inefficient. As an example, when viewing content on a forum I wrote, if you view a thread, I retrieve data from the threads table, the posts table and the user table. The queries from the user and posts table are retrieved via a join and not instantiated as an object, whereas the thread data is called using my Threads class. So how do I get from my current state of affairs to something a little less 'stupid', for want of a better word. Right now I have a DB class that deals with connection and escaping values etc, a parent db query class that deals with the common queries and methods, and all of the other classes (Thread, Upload, Session, Photo and ones thats aren't used Post, User etc ) are children of that. Do I make a big posts class that has the relevant extra attributes that I retrieve from the users (and potentially threads) table? Do I have separate classes that populate each of their relevant attributes with a single query? If so how do I do that? Because of the way my classes are written, based on what I was taught, my db update row method, or insert method both just take the attributes as an array and update all of that, if I have extra attributes from other db tables in each class then how do I rewrite those methods as obbiously updating automatically like that would result in errors? In short I think my understanding is limited right now and I'd like some pointers when it comes to the fundamentals of how to write more complex classes.

  Read the article

• Advice on "Invalid Pointer Operation" when using complex records

  - by Xaz

  Env: Delphi 2007 <JustificationI tend to use complex records quite frequently as they offer almost all of the advantages of classes but with much simpler handling.</Justification Anyhoo, one particularly complex record I have just implemented is trashing memory (later leading to an "Invalid Pointer Operation" error). This is an example of the memory trashing code: sSignature := gProfiles.Profile[_stPrimary].Signature.Formatted(True); On the second time i call it i get "Invalid Pointer Operation" It works OK if i call it like this: AProfile := gProfiles.Profile[_stPrimary]; ASignature := AProfile.Signature; sSignature := ASignature.Formatted(True); Background Code: gProfiles: TProfiles; TProfiles = Record private FPrimaryProfileID: Integer; FCachedProfile: TProfile; ... public < much code removed > property Profile[ProfileType: TProfileType]: TProfile Read GetProfile; end; function TProfiles.GetProfile(ProfileType: TProfileType): TProfile; begin case ProfileType of _stPrimary : Result := ProfileByID(FPrimaryProfileID); ... end; end; function TProfiles.ProfileByID(iID: Integer): TProfile; begin <snip> if LoadProfileOfID(iID, FCachedProfile) then begin Result := FCachedProfile; end else ... end; TProfile = Record private ... public ... Signature: TSignature; ... end; TSignature = Record private public PlainTextFormat : string; HTMLFormat : string; // The text to insert into a message when using this profile function Formatted(bHTML: boolean): string; end; function TSignature.Formatted(bHTML: boolean): string; begin if bHTML then result := HTMLFormat else result := PlainTextFormat; < SNIP MUCH CODE > end; OK, so I have a record within a record within a record, which is approaching Inception level confusion and I'm the first to admit is not really a good model. Clearly i am going to have to restructure it. What I would like from you gurus is a better understanding of why it is trashing the memory (something to do with the string object that is created then freed...) so that i can avoid making these kinds of errors in future. Thanks

  Read the article

• Linux termios VTIME not working?

  - by San Jacinto

  We've been bashing our heads off of this one all morning. We've got some serial lines setup between an embedded linux device and an Ubuntu box. Our reads are getting screwed up because our code usually returns two (sometimes more, sometimes exactly one) message reads instead of one message read per actual message sent. Here is the code that opens the serial port. InterCharTime is set to 4. void COMBaseClass::OpenPort() { cerr<< "openning port"<< port <<"\n"; struct termios newtio; this->fd = -1; int fdTemp; fdTemp = open( port, O_RDWR | O_NOCTTY); if (fdTemp < 0) { portOpen = 0; cerr<<"problem openning "<< port <<". Retrying"<<endl; usleep(1000000); return; } newtio.c_cflag = BaudRate | CS8 | CLOCAL | CREAD ;//| StopBits; newtio.c_iflag = IGNPAR; newtio.c_oflag = 0; /* set input mode (non-canonical, no echo,...) */ newtio.c_lflag = 0; newtio.c_cc[VTIME] = InterCharTime; /* inter-character timer in .1 secs */ newtio.c_cc[VMIN] = readBufferSize; /* blocking read until 1 char received */ tcflush(fdTemp, TCIFLUSH); tcsetattr(fdTemp,TCSANOW,&newtio); this->fd = fdTemp; portOpen = 1; } The other end is configured similarly for communication, and has one small section of particular iterest: while (1) { sprintf(out, "\r\nHello world %lu", ++ulCount); puts(out); WritePort((BYTE *)out, strlen(out)+1); sleep(2); } //while Now, when I run a read thread on the receiving machine, "hello world" is usually broken up over a couple messages. Here is some sample output: 1: Hello 2: world 1 3: Hello 4: world 2 5: Hello 6: world 3 where number followed by a colon is one message recieved. Can you see any error we are making? Thank you. Edit: For clarity, please view section 3.2 of this resource href="http://www.faqs.org/docs/Linux-HOWTO/Serial-Programming-HOWTO.html. To my understanding, with a VTIME of a couple seconds (meaning vtime is set anywhere between 10 and 50, trial-and-error), and a VMIN of 1, there should be no reason that the message is broken up over two separate messages.

  Read the article

• Why boost::recursive_mutex is not working as expected?

  - by Kjir

  I have a custom class that uses boost mutexes and locks like this (only relevant parts): template<class T> class FFTBuf { public: FFTBuf(); [...] void lock(); void unlock(); private: T *_dst; int _siglen; int _processed_sums; int _expected_sums; int _assigned_sources; bool _written; boost::recursive_mutex _mut; boost::unique_lock<boost::recursive_mutex> _lock; }; template<class T> FFTBuf<T>::FFTBuf() : _dst(NULL), _siglen(0), _expected_sums(1), _processed_sums(0), _assigned_sources(0), _written(false), _lock(_mut, boost::defer_lock_t()) { } template<class T> void FFTBuf<T>::lock() { std::cerr << "Locking" << std::endl; _lock.lock(); std::cerr << "Locked" << std::endl; } template<class T> void FFTBuf<T>::unlock() { std::cerr << "Unlocking" << std::endl; _lock.unlock(); } If I try to lock more than once the object from the same thread, I get an exception (lock_error): #include "fft_buf.hpp" int main( void ) { FFTBuf<int> b( 256 ); b.lock(); b.lock(); b.unlock(); b.unlock(); return 0; } This is the output: sb@dex $ ./src/test Locking Locked Locking terminate called after throwing an instance of 'boost::lock_error' what(): boost::lock_error zsh: abort ./src/test Why is this happening? Am I understanding some concept incorrectly?

  Read the article

• Why jQuery selector can't work but getElementById works in this scenario?

  - by Stallman

  Here is the HTML: <html> <head> <script type="text/javascript" src="jquery-1.7.2.min.js"></script> <script type="text/javascript" charset="utf-8" src="jquery-1.7.2.js"></script> <script type="text/javascript" src="access.js"></script> </head> <body> <button id="trigger"></button> <img id= "testElement" style= "position: absolute; border-color: white; top:340px; left:615px;" width="34px" height= "34px" /> </body> </html> And the access.js file is: $(document).ready( function(){ $('#trigger').click(function(){ $('#testElement').src="success.png"; //THIS WON'T WORK. document.getElementById('testElement').src= "success.png"; //BUT THIS WORKS. }); }); I know that if I use $, the return object is a jQuery object. It's not the same as getElementById. But why the jQuery selector can't work here? I need the jQuery object to make more operations like "append/style"... Thanks. UPDATE Too much correct answers appear at almost the same time... Please give more explanations to let me decide who I should give the credit, thanks!!! Sorry for my poor understanding of your correct answer... I just want more detail. Are all the attribute nodes(src/width/height...) not the property of jQuery object? So does the jQuery selector only select DOM Element Node like ? Thank you! 3. List item

  Read the article

• Why is FF on OS X loosing jQuery-UI in click event handler?

  - by Jean-François Beauchamp

  In a web page using jQUery 1.7.1 and jQUery-UI 1.8.18, if I output $.ui in an alert box when the document is ready, I get [object Object]. However when using Firefox, if I output $.ui in a click event handler, I get 'undefined' as result. With other browsers (latest versions of IE, Chrome and Safari), the result is still [object Object] when clicking on the link. Here is my HTML Page: <!doctype html> <html> <head> <title></title> <script src="Scripts/jquery-1.7.1.js" type="text/javascript"></script> <script src="Scripts/jquery-ui-1.8.18.js" type="text/javascript"></script> <script type="text/javascript"> $(document).ready(function () { alert($.ui); // ALERT A $(document).on("click", ".dialogLink", function () { alert($.ui); // ALERT B return false; }); }); </script> </head> <body> <a href="#" class="dialogLink">Click me!</a> </body> </html> In this post, I reduced to its simplest form another problem I was having described here: $(this).dialog is not a function. I created a new post for the sake of clarity, since the real question is different from the original one now that pin-pointed where the problem resided. UPDATE: IF I replace my alerts with simply alert($); I get this result for alert A: function (selector, context) { return new jQuery.fn.init(selector, context, rootjQuery); } and this one for alert B: function (a, b) { return new d.fn.init(a, b, g); } This does not make sense to me, although I may not be understanding well enough what $ is... UPDATE 2: I can only reproduce this problem using Firefox on OS X. On Firefox running on Windows 7, everything is fine.

  Read the article

• Improving Javascript Load Times - Concatenation vs Many + Cache

  - by El Yobo

  I'm wondering which of the following is going to result in better performance for a page which loads a large amount of javascript (jQuery + jQuery UI + various other javascript files). I have gone through most of the YSlow and Google Page Speed stuff, but am left wondering about a particular detail. A key thing for me here is that the site I'm working on is not on the public net; it's a business to business platform where almost all users are repeat visitors (and therefore with caches of the data, which is something that YSlow assumes will not be the case for a large number of visitors). First up, the standard approach recommended by tools such as YSlow is to concatenate it, compress it, and serve it up in a single file loaded at the end of your page. This approach sounds reasonably effective, but I think that a key part of the reasoning here is to improve performance for users without cached data. The system I currently have is something like this * All javascript files are compressed and loaded at the bottom of the page * All javascript files have far future cache expiration dates, so will remain (for most users) in the cache for a long time * Pages only load the javascript files that they require, rather than loading one monolithic file, most of which will not be required Now, my understanding is that, if the cache expiration date for a javascript file has not been reached, then the cached version is used immediately; there is no HTTP request sent at to the server at all. If this is correct, I would assume that having multiple tags is not causing any performance penalty, as I'm still not having any additional requests on most pages (recalling from above that almost all users have populated caches). In addition to this, not loading the JS means that the browser doesn't have to interpret or execute all this additional code which it isn't going to need; as a B2B application, most of our users are unfortunately stuck with IE6 and its painfully slow JS engine. Another benefit is that, when code changes, only the affected files need to be fetched again, rather than the whole set (granted, it would only need to be fetched once, so this is not so much of a benefit). I'm also looking at using LabJS to allow for parallel loading of the JS when it's not cached. So, what do people think is a better approach? In a similar vein, what do you think about a similar approach to CSS - is monolithic better?

  Read the article

< Previous Page | 205 206 207 208 209 210 211 212 213 214 215 216  | Next Page >