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  • Synchronizing DataGridView (DataTable) with the DB

    - by Ezekiel Rage
    Hi! I have the following situation: there is a table in the DB that is queried when the form loads and the retrieved data is filled into a DataGridView via the DataTable underneath. After the data is loaded the user is free to modify the data (add / delete rows, modify entries). The form has 2 buttons: Apply and Refresh. The first one sends the changes to the database, the second one re-reads the data from the DB and erases any changes that have been made by the user. My question is: is this the best way to keep a DataGridView synchronized with the DB (from a users point of view)? For now these are the downsides: the user must keep track of what he is doing and must press the button every while the modifications are lost if the form is closed / app crash / ... I tried sending the changes to the DB on CellEndEdit event but then the user also needs some Undo/Redo functionality and that is ... well ... a different story. So, any suggestions?

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  • How do I make my ArrayList Thread-Safe? Another approach to problem in Java?

    - by thechiman
    I have an ArrayList that I want to use to hold RaceCar objects that extend the Thread class as soon as they are finished executing. A class, called Race, handles this ArrayList using a callback method that the RaceCar object calls when it is finished executing. The callback method, addFinisher(RaceCar finisher), adds the RaceCar object to the ArrayList. This is supposed to give the order in which the Threads finish executing. I know that ArrayList isn't synchronized and thus isn't thread-safe. I tried using the Collections.synchronizedCollection(c Collection) method by passing in a new ArrayList and assigning the returned Collection to an ArrayList. However, this gives me a compiler error: Race.java:41: incompatible types found : java.util.Collection required: java.util.ArrayList finishingOrder = Collections.synchronizedCollection(new ArrayList(numberOfRaceCars)); Here is the relevant code: public class Race implements RaceListener { private Thread[] racers; private ArrayList finishingOrder; //Make an ArrayList to hold RaceCar objects to determine winners finishingOrder = Collections.synchronizedCollection(new ArrayList(numberOfRaceCars)); //Fill array with RaceCar objects for(int i=0; i<numberOfRaceCars; i++) { racers[i] = new RaceCar(laps, inputs[i]); //Add this as a RaceListener to each RaceCar ((RaceCar) racers[i]).addRaceListener(this); } //Implement the one method in the RaceListener interface public void addFinisher(RaceCar finisher) { finishingOrder.add(finisher); } What I need to know is, am I using a correct approach and if not, what should I use to make my code thread-safe? Thanks for the help!

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  • Is there a substitute for blockproc in Matlab?

    - by SetchSen
    I've been using blockproc for processing images blockwise. Unfortunately, blockproc is part of the Image Processing Toolbox, which I don't have on my personal computer. Is there a combination of functions in base Matlab that can substitute for blockproc? My initial guess was to use im2col to transform each block into columns, and then arrayfun to process each column. Then I realized that im2col is also a part of the Image Processing Toolbox, so that doesn't solve my problem.

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  • .NET and C# Exceptions. What is it reasonable to catch.

    - by djna
    Disclaimer, I'm from a Java background. I don't do much C#. There's a great deal of transfer between the two worlds, but of course there are differences and one is in the way Exceptions tend to be thought about. I recently answered a C# question suggesting that under some circstances it's reasonable to do this: try { some work } catch (Exeption e) { commonExceptionHandler(); } (The reasons why are immaterial). I got a response that I don't quite understand: until .NET 4.0, it's very bad to catch Exception. It means you catch various low-level fatal errors and so disguise bugs. It also means that in the event of some kind of corruption that triggers such an exception, any open finally blocks on the stack will be executed, so even if the callExceptionReporter fuunction tries to log and quit, it may not even get to that point (the finally blocks may throw again, or cause more corruption, or delete something important from the disk or database). May I'm more confused than I realise, but I don't agree with some of that. Please would other folks comment. I understand that there are many low level Exceptions we don't want to swallow. My commonExceptionHandler() function could reasonably rethrow those. This seems consistent with this answer to a related question. Which does say "Depending on your context it can be acceptable to use catch(...), providing the exception is re-thrown." So I conclude using catch (Exception ) is not always evil, silently swallowing certain exceptions is. The phrase "Until .NET 4 it is very bad to Catch Exception" What changes in .NET 4? IS this a reference to AggregateException, which may give us some new things to do with exceptions we catch, but I don't think changes the fundamental "don't swallow" rule. The next phrase really bothers be. Can this be right? It also means that in the event of some kind of corruption that triggers such an exception, any open finally blocks on the stack will be executed (the finally blocks may throw again, or cause more corruption, or delete something important from the disk or database) My understanding is that if some low level code had lowLevelMethod() { try { lowestLevelMethod(); } finally { some really important stuff } } and in my code I call lowLevel(); try { lowLevel() } catch (Exception e) { exception handling and maybe rethrowing } Whether or not I catch Exception this has no effect whatever on the excution of the finally block. By the time we leave lowLevelMethod() the finally has already run. If the finally is going to do any of the bad things, such as corrupt my disk, then it will do so. My catching the Exception made no difference. If It reaches my Exception block I need to do the right thing, but I can't be the cause of dmis-executing finallys

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  • Hide jQuery Accordion while loading

    - by zac
    I am testing a site build with a slow connection and I noticed the jQuery Accordion stays expanded for a long time, until the rest of the site is loaded, and then finally collapses. Not very pretty. I was wondering how I could keep it collapsed through the loading process and only expand when clicked. I am working with the standalone 1.6 version of the accordion plugin. The basic structure : <div class="sidebar"> <ul id="navigation" class="ui-accordion-container"> <li><a class="head" href="#">1</a> <ul class="sub"> <li><a href="#">1a</a></li> <li><a href="#">2a</a></li> </ul> </li> </ul> </div> and the script jQuery().ready(function(){ jQuery('#navigation').accordion({ active: 'false', header: '.head', navigation: true, animated: 'easeslide', collapsible: true }); }); I tried to hide the elements in the CSS to keep them from appearing while loading but all that achieved is in having them always hidden. Maybe the problem is in the CSS I have a background image in each of the sub menus: #navigation{ margin:0px; margin-left: 10px; padding:0px; text-indent:0px; font-size: 1.1em; width:200px; text-transform: uppercase; padding-bottom: 30px; } #navigation ul{ border-width:0px; margin:0px; padding:0px; text-indent:0px; } #navigation li{ list-style:none outside none; } #navigation li ul{ height:185px; overflow:auto; } #navigation li ul.sub{ background:url('../images/sub.jpg') no-repeat; dispaly: block; } #navigation li li a{ color:#000000; display:block; text-indent:20px; text-decoration: none; padding: 6px 0; } #navigation li li a:hover{ background-color:#FFFF99; color:#FF0000; } Thanks in advance for any advice on how to have this thing run a little smoother and having the accordion always collapsed. -edit - I forgot to mention that I am also hoping for a solution that will allow the nav to still be accessible for those without javscript.

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  • Why do garbage collectors freeze execution?

    - by Martin
    I was thinking about garbage collection on the way home, and I began wondering, why does the garbage collector totally freeze execution of a program? Personally I would have designed it to block any threads which try to allocate a new object, but threads which were running would be left alone. I can't imagine any situation where this would be a problem compared to how a garbage collector currently works.

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  • Delete text in text box using PHP

    - by Idealflip
    Hello, is there a way to remove text from a text box using a submit button? I don't want to delete text from all boxes on the form. And I don't want to delete text 'onclick', for the element. I need the code to clear the text box, to initiate from within a block. Thanks for your help!

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  • Uncatchable errors in node.js

    - by Peter Burns
    So I'm trying to write a simple TCP socket server that broadcasts information to all connected clients. So when a user connects, they get added to the list of clients, and when the stream emits the close event, they get removed from the client list. This works well, except that sometimes I'm sending a message just as a user disconnects. I've tried wrapping stream.write() in a try/catch block, but no luck. It seems like the error is uncatchable.

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  • Trappings MySQL Warnings on Calls Wrapped in Classes -- Python

    - by chernevik
    I can't get Python's try/else blocks to catch MySQL warnings when the execution statements are wrapped in classes. I have a class that has as a MySQL connection object as an attribute, a MySQL cursor object as another, and a method that run queries through that cursor object. The cursor is itself wrapped in a class. These seem to run queries properly, but the MySQL warnings they generate are not caught as exceptions in a try/else block. Why don't the try/else blocks catch the warnings? How would I revise the classes or method calls to catch the warnings? Also, I've looked through the prominent sources and can't find a discussion that helps me understand this. I'd appreciate any reference that explains this. Please see code below. Apologies for verbosity, I'm newbie. #!/usr/bin/python import MySQLdb import sys import copy sys.path.append('../../config') import credentials as c # local module with dbase connection credentials #============================================================================= # CLASSES #------------------------------------------------------------------------ class dbMySQL_Connection: def __init__(self, db_server, db_user, db_passwd): self.conn = MySQLdb.connect(db_server, db_user, db_passwd) def getCursor(self, dict_flag=True): self.dbMySQL_Cursor = dbMySQL_Cursor(self.conn, dict_flag) return self.dbMySQL_Cursor def runQuery(self, qryStr, dict_flag=True): qry_res = runQueryNoCursor(qryStr=qryStr, \ conn=self, \ dict_flag=dict_flag) return qry_res #------------------------------------------------------------------------ class dbMySQL_Cursor: def __init__(self, conn, dict_flag=True): if dict_flag: dbMySQL_Cursor = conn.cursor(MySQLdb.cursors.DictCursor) else: dbMySQL_Cursor = conn.cursor() self.dbMySQL_Cursor = dbMySQL_Cursor def closeCursor(self): self.dbMySQL_Cursor.close() #============================================================================= # QUERY FUNCTIONS #------------------------------------------------------------------------------ def runQueryNoCursor(qryStr, conn, dict_flag=True): dbMySQL_Cursor = conn.getCursor(dict_flag) qry_res =runQueryFnc(qryStr, dbMySQL_Cursor.dbMySQL_Cursor) dbMySQL_Cursor.closeCursor() return qry_res #------------------------------------------------------------------------------ def runQueryFnc(qryStr, dbMySQL_Cursor): qry_res = {} qry_res['rows'] = dbMySQL_Cursor.execute(qryStr) qry_res['result'] = copy.deepcopy(dbMySQL_Cursor.fetchall()) qry_res['messages'] = copy.deepcopy(dbMySQL_Cursor.messages) qry_res['query_str'] = qryStr return qry_res #============================================================================= # USAGES qry = 'DROP DATABASE IF EXISTS database_of_armaments' dbConn = dbMySQL_Connection(**c.creds) def dbConnRunQuery(): # Does not trap an exception; warning displayed to standard error. try: dbConn.runQuery(qry) except: print "dbConn.runQuery() caught an exception." def dbConnCursorExecute(): # Does not trap an exception; warning displayed to standard error. dbConn.getCursor() # try/except block does catches error without this try: dbConn.dbMySQL_Cursor.dbMySQL_Cursor.execute(qry) except Exception, e: print "dbConn.dbMySQL_Cursor.execute() caught an exception." print repr(e) def funcRunQueryNoCursor(): # Does not trap an exception; no warning displayed try: res = runQueryNoCursor(qry, dbConn) print 'Try worked. %s' % res except Exception, e: print "funcRunQueryNoCursor() caught an exception." print repr(e) #============================================================================= if __name__ == '__main__': print '\n' print 'EXAMPLE -- dbConnRunQuery()' dbConnRunQuery() print '\n' print 'EXAMPLE -- dbConnCursorExecute()' dbConnCursorExecute() print '\n' print 'EXAMPLE -- funcRunQueryNoCursor()' funcRunQueryNoCursor() print '\n'

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  • Threadsafe way of exposing keySet()

    - by Jake
    This must be a fairly common occurrence where I have a map and wish to thread-safely expose its key set: public MyClass { Map<String,String> map = // ... public final Set<String> keys() { // returns key set } } Now, if my "map" is not thread-safe, this is not safe: public final Set<String> keys() { return map.keySet(); } And neither is: public final Set<String> keys() { return Collections.unmodifiableSet(map.keySet()); } So I need to create a copy, such as: public final Set<String> keys() { return new HashSet(map.keySet()); } However, this doesn't seem safe either because that constructor traverses the elements of the parameter and add()s them. So while this copying is going on, a ConcurrentModificationException can happen. So then: public final Set<String> keys() { synchronized(map) { return new HashSet(map.keySet()); } } seems like the solution. Does this look right?

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  • Iterate through every file in one directory

    - by Andrew
    How do i write a loop in ruby so that I can execute a block of code on each file? I'm new to ruby, and I've concluded that the way to do this is a do each loop. The ruby file will be executed from a different directory than the directory I want to loop through. I've tried the Dir.foreach and I couldn't get it to work.

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  • What can i use to journal writes to file system

    - by Dmitry
    Hello, all I need to track all writes to files in order to have synchronized version of files on different place (server or just other directory, not considerable). Let it: all files located in same directory feel free to create some system files (e.g. SomeFileName.Ext~temp-data) no one have concurrent access to synced directory; nobody spoil ours meta-files or change real-files before we do postponed writes (like a commits) do not to care recovering "local" changes in case of crash; system can just rolled back to state of "server" by simple copy from it significant to have it transparent to use (so programmer must just call ordinary fopen(), read(), write()) It must be guaranteed that copy of files which "server" have is consistent. That is whole files scope existed in some moment of time. They may be sufficiently outdated but it must be fair snapshot of all files at some time. As i understand i should overload writing logic to collect data in order sent changes to "server". For example writing to temporary File~tmp. And so i have to overload reads in order program could read actual data of file. It would be great if you suggest some existing library (java or c++, it is unimportant) or solution (VCS customizing?). Or give hints how should i write it by myself. edit: After some reading i have more precision requirements: I need COW (Copy-on-write) wrapper for fopen(),fwrite(),.. or interceptor (hook) WriteFile() and other FS api system calls. Log-structured file system in userspace would be a alternative too.

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  • CSS/JS: Evenly spreading elements across multiple lines

    - by David Lawson
    How would you go about evenly spreading elements across multiple lines, for example: wrapper div: <div style="text-align: center"> elements inside: <div style="display: inline-block; padding-left: 10px; padding-right: 10px;">Element</div> Instead of only having one element on the next line (wrapped): Element 1 Element 2 Element 3 Element 4 Element 5 Element 6 It does this, spreading out the elements: Element 1 Element 2 Element 3 Element 4 Element 5 Element 6

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  • Using jQuery to disable CSS inheritance

    - by Buzzedword
    Is there a way to use jQuery (or generic javascript) to disable CSS inheritance on a block level? For example, if I am pulling in an external resource via javascript, say pastie.org, they will have their own CSS that my CSS overrides. I would like to place the embed code into its own container that has CSS inheritance disabled. This is not my own CSS structure, so I can't rename IDs Classes or inline anything to make it work, the holy grail of inheritance blocking is my last resort.

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  • How do I write a powershell script that gets the file with the most recent last write time from a fo

    - by Shoko
    The subject line says it all. I'd also like to do this using pipes. I figured that I could use Get-ChildItem, Measure-Object and Where-Object, but Measure-Object doesn't like dates. Should I have a script block which loops through each item returned from Get-ChildItem and does a comparison to see if it's the most recent? I thought that there should be a handy PS cmdlet for that.

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  • Facebook/Youtube Like Multiple Items Select

    - by bradenkeith
    Before we continue: It can't be a predefined list. I need it sort of like this: http://loopj.com/tokeninput/demo.html ... A jQuery plugin that allows the user to type a string of words, press enter, and it makes it a block of text, from there they can press the X to get rid of it, or type more key words into the input area. I've found many things that do this, but all are pulling information from a predefined list of choices.

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  • IoC and DI framework for .Net applications

    - by Lijo
    Hi Can you please explain how the following three are different in their intent? 1) Policy Injection Application Block 2) Structure Map IoC Managed 3) Managed Extensibility Framework In terms of the common tasks they do, which is simpler/aligned with generics and C# 3.0 ? Thanks Lijo

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  • Dependency Injection into your Singleton

    - by Langali
    I have a singleton that has a spring injected Dao (simplified below): public class MyService<T> implements Service<T> { private final Map<String, T> objects; private static MyService instance; MyDao myDao; public void set MyDao(MyDao myDao) { this. myDao = myDao; } private MyService() { this.objects = Collections.synchronizedMap(new HashMap<String, T>()); // start a background thread that runs for ever } public static synchronized MyService getInstance() { if(instance == null) { instance = new MyService(); } return instance; } public void doSomething() { myDao.persist(objects); } } My spring config will probably look like this: <bean id="service" class="MyService" factory-method="getInstance"/> But this will instantiate the MyService during startup. Is there a programmatic way to do a dependency injection of MyDao into MyService, but not have spring manage the MyService? Basically I want to be able to do this from my code: MyService.getInstance().doSomething(); while having spring inject the MyDao for me.

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  • Client server architecture question

    - by Shane Fulmer
    I am working on a client server system, and am running into issues where multiple clients are executing an action at the same time. We are able to solve this by locking on the critical section of code, which ensures that the first client will complete the action before the second client enters the code block. My question is this: our server is also clustered, so multiple instances of the server itself can exist, which recreates the same problem as before. How could we solve this problem? Thanks!

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  • CSS Positioning

    - by Davey
    Trying to mess with this wordpress theme and can't figure out why the sidebar is stacking underneath the content block. Any help would be very appreciated. http://www.buffalostreetbooks.com/events CSS: body { font-family: Arial, Helvetica, Verdana, Sans-serif; font-size: 10pt; background-color: #692022; background-image:url("http://www.buffalostreetbooks.com/wp-content/themes/autumn-leaves/images/repeatflower.png"); } body,h1#blog-title { margin: 0; padding: 0; } a { color: blue; } a:hover { color: #FF8C00; } a img { border: 0 none; } #wrapper { width: 960px; margin: 0 auto; background-color: #F4FBF4; border-left: 1px solid #ccc; border-right: 1px solid #ccc; } #header { background-image:url("http://www.buffalostreetbooks.com/wp-content/themes/autumn-leaves/images/headertime.png"); width:768px; height: 200px; } #inner-header { padding: 125px 1em 0; } h1#blog-title { font-size: 2em; } h1#blog-title a { color: #800000; } .entry-title a { color: #CD853F; } h1#blog-title a, .entry-title a, #footer a { text-decoration: none; } h1#blog-title a:hover, .entry-title a:hover, #footer a:hover { text-decoration: underline; } div.skip-link { display: none; } #menu { border-bottom: 1px solid #ccc; } #menu a { color: #000; } #menu a:hover { text-decoration: underline; } #menu li.current_page_item a, #menu li.current_page_item a:hover { background-color: #DFC28B; text-decoration: none; } #content { padding: 1em; width:600px; } .entry-title { font-size: 1.5em; margin: 1em 0 0 0; } abbr.published { color: #666; border: 0 none; } .entry-meta, .entry-date { color: #666; } #comments-list .avatar { float: left; margin-right: 1em; } #comments-list .n { font-weight: bold; } .entry-meta, .comment-meta { font-style: italic; } #comments-list p { clear: left; } #primary { padding-left: 1em; font-size: 0.9em; border-left: 1px solid #ccc; border-bottom: 1px solid #ccc; background-color: #FFFACD; } #footer { text-align: center; font-size: 0.8em; border-top: 1px solid #ccc; border-bottom: 1px solid #ccc; margin-bottom: 1em; } #inner-footer { padding: 1em 0; } .entry-meta, .entry-meta a, .comment-meta, .comment-meta a, .sidebar, .sidebar a, #footer, #footer a { color: #666; } /* LAYOUT: Two-Column (Right) DESCRIPTION: Two-column fluid layout with one sidebars right of content */ div#container { margin:0 0 0 0; width:960px; height:100%; } div#content { margin:0 0 0 0; } div.sidebar { overflow:hidden; width:280px; min-height:500px; clear:both; } div#secondary { clear:right; } div#footer { clear:both; width:100%; } /* Just some example content */ div#menu { height:2em; width:100%; } div#menu ul,div#menu ul ul { line-height:2em; list-style:none; margin:0; padding:0; } div#menu ul a { display:block; margin-right:1em; padding:0 0.5em; text-decoration:none; } div#menu ul ul ul a { font-style:italic; } div#menu ul li ul { left:-999em; position:absolute; } div#menu ul li:hover ul { left:auto; } .entry-title,.entry-meta { clear:both; } div#primary { } form#commentform .form-label { margin:1em 0 0; } form#commentform span.required { background:#fff; color:#c30; } form#commentform,form#commentform p { padding:0; } input#author,input#email,input#url,textarea#comme nt { padding:0.2em; } div.comments ol li { margin:0 0 3.5em; } textarea#comment { height:13em; margin:0 0 0.5em; overflow:auto; width:66%; } .alignright,img.alignright{ float:right; margin:1em 0 0 1em; } .alignleft,img.alignleft{ float:left; margin:1em 1em 0 0; } .aligncenter,img.aligncenter{ display:block; margin:1em auto; text-align:center; } div.gallery { clear:both; height:180px; margin:1em 0; width:100%; } p.wp-caption-text{ font-style:italic; } div.gallery dl{ margin:1em auto; overflow:hidden; text-align:center; } div.gallery dl.gallery-columns-1 { width:100%; } div.gallery dl.gallery-columns-2 { width:49%; } div.gallery dl.gallery-columns-3 { width:33%; } div.gallery dl.gallery-columns-4 { width:24%; } div.gallery dl.gallery-columns-5 { width:19%; } div#nav-above { margin-bottom:1em; } div#nav-below { margin-top:1em; } div#nav-images { height:150px; margin:1em 0; } div.navigation { height:1.25em; } div.navigation div.nav-next { float:right; text-align:right; } div.sidebar h3 { font-size:1.2em; } div.sidebar input#s { width:7em; } div.sidebar li { list-style:none; margin:0 0 2em; } div.sidebar li form { margin:0.2em 0 0; padding:0; } div.sidebar ul ul { margin:0 0 0 2em; } div.sidebar ul ul li { list-style:disc; margin:0; } div.sidebar ul ul ul { margin:0 0 0 0.5em; } div.sidebar ul ul ul li { list-style:circle; } div#menu ul li,div.gallery dl,div.navigation div.nav-previous { float:left; } input#author,input#email,input#url,div.navigation div { width:50%; } div.gallery *,div.sidebar div,div.sidebar h3,div.sidebar ul { margin:0; padding:0; }

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  • PHP's DOMXPath is stripping out my tags inside the matched text.

    - by Mint
    I asked this question yesterday, and at the time it was just what I needed, but while working with some live data I discovered that is wasn't quite doing what I expected. http://stackoverflow.com/questions/2571232/parse-html-with-phps-html-domdocument I gets the data from the HTML page, but then it also strips out all the HTML tags inside the captured block of text, which isn't what I want. (I might wan't to take some of the tags out, but not all, and this can be done later)

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