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  • NHibernate FetchMode.Lazy

    - by RyanFetz
    I have an object which has a property on it that has then has collections which i would like to not load in a couple situations. 98% of the time i want those collections fetched but in the one instance i do not. Here is the code I have... Why does it not set the fetch mode on the properties collections? [DataContract(Name = "ThemingJob", Namespace = "")] [Serializable] public class ThemingJob : ServiceJob { [DataMember] public virtual Query Query { get; set; } [DataMember] public string Results { get; set; } } [DataContract(Name = "Query", Namespace = "")] [Serializable] public class Query : LookupEntity<Query>, DAC.US.Search.Models.IQueryEntity { [DataMember] public string QueryResult { get; set; } private IList<Asset> _Assets = new List<Asset>(); [IgnoreDataMember] [System.Xml.Serialization.XmlIgnore] public IList<Asset> Assets { get { return _Assets; } set { _Assets = value; } } private IList<Theme> _Themes = new List<Theme>(); [IgnoreDataMember] [System.Xml.Serialization.XmlIgnore] public IList<Theme> Themes { get { return _Themes; } set { _Themes = value; } } private IList<Affinity> _Affinity = new List<Affinity>(); [IgnoreDataMember] [System.Xml.Serialization.XmlIgnore] public IList<Affinity> Affinity { get { return _Affinity; } set { _Affinity = value; } } private IList<Word> _Words = new List<Word>(); [IgnoreDataMember] [System.Xml.Serialization.XmlIgnore] public IList<Word> Words { get { return _Words; } set { _Words = value; } } } using (global::NHibernate.ISession session = NHibernateApplication.GetCurrentSession()) { global::NHibernate.ICriteria criteria = session.CreateCriteria(typeof(ThemingJob)); global::NHibernate.ICriteria countCriteria = session.CreateCriteria(typeof(ThemingJob)); criteria.AddOrder(global::NHibernate.Criterion.Order.Desc("Id")); var qc = criteria.CreateCriteria("Query"); qc.SetFetchMode("Assets", global::NHibernate.FetchMode.Lazy); qc.SetFetchMode("Themes", global::NHibernate.FetchMode.Lazy); qc.SetFetchMode("Affinity", global::NHibernate.FetchMode.Lazy); qc.SetFetchMode("Words", global::NHibernate.FetchMode.Lazy); pageIndex = Convert.ToInt32(pageIndex) - 1; // convert to 0 based paging index criteria.SetMaxResults(pageSize); criteria.SetFirstResult(pageIndex * pageSize); countCriteria.SetProjection(global::NHibernate.Criterion.Projections.RowCount()); int totalRecords = (int)countCriteria.List()[0]; return criteria.List<ThemingJob>().ToPagedList<ThemingJob>(pageIndex, pageSize, totalRecords); }

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  • Can parser combination be made efficient?

    - by Jon Harrop
    Around 6 years ago, I benchmarked my own parser combinators in OCaml and found that they were ~5× slower than the parser generators on offer at the time. I recently revisited this subject and benchmarked Haskell's Parsec vs a simple hand-rolled precedence climbing parser written in F# and was surprised to find the F# to be 25× faster than the Haskell. Here's the Haskell code I used to read a large mathematical expression from file, parse and evaluate it: import Control.Applicative import Text.Parsec hiding ((<|>)) expr = chainl1 term ((+) <$ char '+' <|> (-) <$ char '-') term = chainl1 fact ((*) <$ char '*' <|> div <$ char '/') fact = read <$> many1 digit <|> char '(' *> expr <* char ')' eval :: String -> Int eval = either (error . show) id . parse expr "" . filter (/= ' ') main :: IO () main = do file <- readFile "expr" putStr $ show $ eval file putStr "\n" and here's my self-contained precedence climbing parser in F#: let rec (|Expr|) (P(f, xs)) = Expr(loop (' ', f, xs)) and shift oop f op (P(g, xs)) = let h, xs = loop (op, g, xs) loop (oop, f h, xs) and loop = function | ' ' as oop, f, ('+' | '-' as op)::P(g, xs) | (' ' | '+' | '-' as oop), f, ('*' | '/' as op)::P(g, xs) | oop, f, ('^' as op)::P(g, xs) -> let h, xs = loop (op, g, xs) let op = match op with | '+' -> (+) | '-' -> (-) | '*' -> (*) | '/' -> (/) | '^' -> pown loop (oop, op f h, xs) | _, f, xs -> f, xs and (|P|) = function | '-'::P(f, xs) -> let f, xs = loop ('~', f, xs) P(-f, xs) | '('::Expr(f, ')'::xs) -> P(f, xs) | c::xs when '0' <= c && c <= '9' -> P(int(string c), xs) My impression is that even state-of-the-art parser combinators waste a lot of time back tracking. Is that correct? If so, is it possible to write parser combinators that generate state machines to obtain competitive performance or is it necessary to use code generation?

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  • What is the mysql 5.5 equivalent for the sys.dm_fts_index_keywords_by_document in sql 2008

    - by djsurge
    I'm making a web application that uses the data in the sys.dm_fts_index_keywords_by_document. I'm interested how many times a given term occurs in each string that is indexed. For example, I have a table with a column called comments, the table has various strings in the comments field. When I make that column full text searchable, the dm_fts_index_keywords_by_document is created and I can see the word per document data. Can i do the same thing in mySQL?

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  • Connection error with heroku db:push with postgresql

    - by Toby Hede
    I have suddenly started seeing this strange error when trying to push my database to heroku. > heroku db:push Auto-detected local database: postgres://infinity:infinity@localhost/infinity_development?encoding=utf8 Failed to connect to database: Sequel::DatabaseConnectionError -> TypeError wrong argument type String (expected Array) My app works fine - the credentials are all set locally.

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  • How do I bind to something outside a datacontext.

    - by AKRamkumar
    I have a listbox in WPF that is in the Layout Root. I also have a Frame that is in the Layout Root as well. The listbox is composed of items that have a string(Name) and a framework element(UI). How do I bind the frame's content to be the UI property of the listbox's selected item property? If you need a codebehind, how would you do this in MVVM

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  • How to with extract url from tweet using Regular Expressions

    - by neutreno
    Ok so i'm executing the following line of code in javascript RegExp('(http:\/\/t.co\/)[a-zA-Z0-9\-\.]{8}').exec(tcont); where tcont is equal to some string like 'Test tweet to http://t.co/GXmaUyNL' (the content of a tweet obtained by jquery). However it is returning, in the case above for example, 'http://t.co/GXmaUyNL,http://t.co/'. This is frustracting because I want the url without the bit on the end - after and including the comma. Any ideas why this is appearing? Thanks

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  • average velocity, as3

    - by VideoDnd
    Hello, I need something accurate I can plug equations in to if you can help. How would you apply the equation bellow? Thanks guys. AVERAGE VELOCITY AND DISPLACEMENT average velocity V=X/T displacement x=v*T more info example I have 30 seconds and a field that is 170 yards. What average velocity would I need my horse to travel at to reach the end of the field in 30 seconds. I moved the decimal places around and got this. Here's what I tried 'the return value is close, but not close enough' FLA here var TIMER:int = 10; var T:int = 0; var V:int = 5.6; var X:int = 0; var Xf:int = 17000/10*2; var timer:Timer = new Timer(TIMER,Xf); timer.addEventListener(TimerEvent.TIMER, incrementCounter); timer.start(); function formatCount(i:int):String { var fraction:int = Math.abs(i % 100); var whole:int = Math.abs(i / 100); return ("0000000" + whole).substr(-7, 7) + "." + (fraction < 10 ? "0" + fraction : fraction); } function incrementCounter(event:TimerEvent) { T++; X = Math.abs(V*T); text.text = formatCount(X); } tests TARGET 5.6yards * 30seconds = 168yards INTEGERS 135.00 in 30 seconds MATH.ROUND 135.00 in 30 seconds NUMBERS 140.00 in 30 seconds control timer 'I tested with this and the clock on my desk' var timetest:Timer = new Timer(1000,30); var Dplus:int = 17000; timetest.addEventListener(TimerEvent.TIMER, cow); timetest.start(); function cow(evt:TimerEvent):void { tx.text = String("30 SECONDS: " + timetest.currentCount); if(timetest.currentCount> Dplus){ timetest.stop(); } } //far as I got...couldn't get delta to work... T = (V*timer.currentCount); X += Math.round(T);

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  • WPF - Random hanging with file browser attached behaviour.

    - by Stimul8d
    Hi, I have an attached behavior defined thusly,.. public static class FileBrowserBehaviour { public static bool GetBrowsesOnClick(DependencyObject obj) { return (bool)obj.GetValue(BrowsesOnClickProperty); } public static void SetBrowsesOnClick(DependencyObject obj, bool value) { obj.SetValue(BrowsesOnClickProperty, value); } // Using a DependencyProperty as the backing store for BrowsesOnClick. This enables animation, styling, binding, etc... public static readonly DependencyProperty BrowsesOnClickProperty = DependencyProperty.RegisterAttached("BrowsesOnClick", typeof(bool), typeof(FileBrowserBehaviour), new FrameworkPropertyMetadata(false, new PropertyChangedCallback(BrowsesOnClickChanged))); public static void BrowsesOnClickChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) { FrameworkElement fe = obj as FrameworkElement; if ((bool)args.NewValue) { fe.PreviewMouseLeftButtonDown += new MouseButtonEventHandler(OpenFileBrowser); } else { fe.PreviewMouseLeftButtonDown -= new MouseButtonEventHandler(OpenFileBrowser); } } static void OpenFileBrowser(object sender, MouseButtonEventArgs e) { var tb = sender as TextBox; if (tb.Text.Length < 1 || tb.Text=="Click to browse..") { OpenFileDialog ofd = new OpenFileDialog(); ofd.Filter = "Executables | *.exe"; if (ofd.ShowDialog() == true) { Debug.WriteLine("Setting textbox text-" + ofd.FileName); tb.Text = ofd.FileName; Debug.WriteLine("Set textbox text"); } } } } It's a nice simple attached behavior which pops open an OpenFileDialog when you click on a textbox and puts the filename in the box when you're done. It works maybe 40% of the time but the rest of the time the whole app hangs. The call stack at this point looks like this - [Managed to Native Transition] WindowsBase.dll!MS.Win32.UnsafeNativeMethods.GetMessageW(ref System.Windows.Interop.MSG msg, System.Runtime.InteropServices.HandleRef hWnd, int uMsgFilterMin, int uMsgFilterMax) + 0x15 bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.GetMessage(ref System.Windows.Interop.MSG msg, System.IntPtr hwnd, int minMessage, int maxMessage) + 0x48 bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame frame = {System.Windows.Threading.DispatcherFrame}) + 0x8b bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.PushFrame(System.Windows.Threading.DispatcherFrame frame) + 0x49 bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.Run() + 0x4c bytes PresentationFramework.dll!System.Windows.Application.RunDispatcher(object ignore) + 0x1e bytes PresentationFramework.dll!System.Windows.Application.RunInternal(System.Windows.Window window) + 0x6f bytes PresentationFramework.dll!System.Windows.Application.Run(System.Windows.Window window) + 0x26 bytes PresentationFramework.dll!System.Windows.Application.Run() + 0x19 bytes Debugatron.exe!Debugatron.App.Main() + 0x5e bytes C# [Native to Managed Transition] [Managed to Native Transition] mscorlib.dll!System.AppDomain.nExecuteAssembly(System.Reflection.Assembly assembly, string[] args) + 0x19 bytes mscorlib.dll!System.Runtime.Hosting.ManifestRunner.Run(bool checkAptModel) + 0x6e bytes mscorlib.dll!System.Runtime.Hosting.ManifestRunner.ExecuteAsAssembly() + 0x84 bytes mscorlib.dll!System.Runtime.Hosting.ApplicationActivator.CreateInstance(System.ActivationContext activationContext, string[] activationCustomData) + 0x65 bytes mscorlib.dll!System.Runtime.Hosting.ApplicationActivator.CreateInstance(System.ActivationContext activationContext) + 0xa bytes mscorlib.dll!System.Activator.CreateInstance(System.ActivationContext activationContext) + 0x3e bytes Microsoft.VisualStudio.HostingProcess.Utilities.dll!Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone() + 0x23 bytes mscorlib.dll!System.Threading.ThreadHelper.ThreadStart_Context(object state) + 0x66 bytes mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state) + 0x6f bytes mscorlib.dll!System.Threading.ThreadHelper.ThreadStart() + 0x44 bytes Now, I've seen this kind of thing before when doing some asynchronous stuff but there's none of that going on at that point. The only thread alive is the UI thread! Also, I always get that last debug statement when it does hang. Can anyone point me in the right direction? This one's driving me crazy!

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  • Not able to delete list which dynamically created with jquery.

    - by shin
    I have two html here. The first one is dynamically generated by php and second one is just html to test. I also have the following jquery. When I click a cross with class delete in the second ones(plain html), it works nicely. However when I click a cross in the first ones, it does not work. It redirect me to the home page with # at the end. I am hoping someone point out what I am doing wrong. Thank in advance. HTML First part (dyanmicall generated) <ul style="display: block;" id="message"> <li class="41"> <span class="user"><strong>shin</strong></span> <span class="msg"> delete this as well</span> <span class="date">2010-01-15 07:47:31</span> <a href="#" id="41" class="delete">x</a> <div class="clear"></div></li> <li class="40"> <span class="user"><strong>shin</strong></span> <span class="msg"> delete me as well</span> <span class="date">2010-01-14 16:01:44</span> <a href="#" id="40" class="delete">x</a> <div class="clear"></div></li> ... ...</ul> Second part which is plain html <ul id="another"> <li><a href="#">you can't delete me</a></li> <li><a href="#" class="delete">delete this</a></li> <li><a href="#" class="delete">delete this</a></li> </ul> Here is jquery $(".delete").click(function(event) { event.preventDefault(); loading.fadeIn(); var commentContainer = $(this).parent(); var id = $(this).attr("id"); // var string = 'id='+ id ; $.ajax({ type: "POST", url: "index.php/admin/messages/changestatus/"+id, // data: string, cache: false, success: function(){ commentContainer.slideUp('slow', function() {$(this).remove();}); loading.fadeOut(); } }); return false; }); I am using CodeIgniter by the way.

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  • LINQ "table" variable

    - by Cat
    I'm trying to turn a method I have right now into a more "generic" method that returns a string. Right now, the method uses a statement like this: var app = (from d in testContext.DAPPs where d.sserID == (Guid)user.ProviderUserKey select d).ToList(); I process the results of "app", add extra text etc. The piece that changes (that I need to make more "generic") is the table name (DAPPs). Is there a way I can do that, or, a better way to go around this all together?

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  • pass Multilple paramets in struts action with same parameter name

    - by raju
    Hi I would like to pass Multiple parameters for single param in action tag. Ex: abc Answers.jsp I have getters and setters for hint (String) variable in my action. Currently i can be able to get parameter value for hint variable as abc if i send one. I would like to send multiple parameters for same variable(hint) ex: abc, xyz how can achieve the above. Thanks in advance Raju

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  • File upload in asp.net mvc using ajax

    - by Maxim
    Hello! i have a simple html form with two controls: input-text and input-file i need to write an ajax query (using jquery is better) to send data (file and value from text field to mvc acton) i wrote $.ajax({ type: "POST", url: "/controller/acton", enctype: 'multipart/form-data', data: 'text=' + $("#text").val() + '&file=' + $("#file").val() ... and in controller: [HttpPost] public ActionResult StoreItem(FormCollection forms) { foreach (string inputTagName in Request.Files) ... returns null in Request... Thank you

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  • If/Then in SQL Embedded in VBA

    - by Daniel
    I've got a string like this in my Excel VBA: strSQL = "SELECT * FROM Total WHERE (SimulationID = (" & TextBox1.Text & ") And Test1 = (" & Example & "))" However, sometimes Test will be 'is null', which makes the query And Example = is NULL How can I change it to add an if/then statement or something to make it say And Example is null when Example has a value of "is null"?

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  • Using Visual Studio Intellisense for building jQuery selector strings

    - by jslatts
    This is a minor issue, but one I find myself running into: When I am using jQuery in Visual Studio 2010, I find myself frequently typing: $(#S using Intellisense to find the SomeID object ID: $(#SomeID).click( function() { etc.. }) then going back and adding quotes: $('#SomeID').click( function() { etc.. }) I find it annoying that if I add the quote first, Visual Studio goes into string mode and I lose Intellisense for finding the object's ID or class. Am I doing it wrong?

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  • Error: The conversion of a nvarchar data type to a datetime data type resulted in an out-of-range value

    - by CPM
    I know that there are simmilar questions like this on the forum, however I am still having problems to update a datetime field o the database. I dont get any problems when inserting but I get problems when updating and I am formating the same way , like this: e.Values.Item("SelectionStartDate") = Format(startdate, "yyyy-MM-dd") + " " + startTime1 + ".000" startTime is of type string. I have tried different solution that I came across on the internet but still get this error. Please help. Thanks in advance

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  • How to access FlashVars in flash

    - by RBADS
    Hi this is my code in imageload.html http://triangleyoga.com/images/krishna.gif&audio=http://audio.iskcondesiretree.info/02_-_ISKCON_Swamis/His_Holiness_Radhanath_Swami/Bhajans/Hare_Krishna/IDT_70-Hare_Krishna_-_Radhanath_Swami.mp3"/ and in my as3 file i tried to used flashvars as: var params:Object = LoaderInfo(this.root.loaderInfo).parameters; var var1:String = params['img']; trace(var1); But it shows null.Any idea ? Thank you

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  • Open .NET app from Web Page.

    - by Sheldon
    Hi, I just need to be able to open a .NET app (click once) from within an ASP.NET web page, and pass 2 string parameter to the app. How can I do this? Any example please, with any method to do it. Thank you in advance.

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  • Embed XAML in XML Schema

    - by Michael Stoll
    I'm developping a xml data format. Besides other data there should be a xaml drawing. So I wanted to have a xml element, which can contain any valid xaml. How can this be expressed in the XML Schema? I tried to import the xaml schema, but I couldn't find a xsd file for it. The makeshift would be to use an encoded string.

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  • Grails validateable not work for non-persistent domain class

    - by Hoàng Long
    I followed the instruction here: http://www.grails.org/doc/latest/guide/7.%20Validation.html and added into config.groovy: grails.validateable.classes = [liningtest.Warm'] Then added in src/groovy/Warm.groovy (it's a non-persistent domain class): package liningtest import org.codehaus.groovy.grails.validation.Validateable class Warm { String name; int happyCite; Warm(String n, int h) { this.name = n; this.happyCite = h; } static constraints = { name(size: 1..50) happyCite(min: 100) } } But it just doesn't work (both "blank false" & "size: 0..25") for the "hasErrors" function. It always returns false, even when the name is 25. Is this a Grails bug, if yes, is there any work-around? I'm using Grails 1.3.3 UPDATE: I have updated the simplified code. And now I know that constraint "size" can't be used with "blank", but still does not work. My test class in test/unit/liningtest/WarmTests.groovy package liningtest import grails.test.* class WarmTests extends GrailsUnitTestCase { protected void setUp() { super.setUp() } protected void tearDown() { super.tearDown() } void testSomething() { def w = new Warm('Hihi', 3) assert (w.happyCite == 3) assert (w.hasErrors() == true) } } And the error I got: <?xml version="1.0" encoding="UTF-8" ?> <testsuite errors="1" failures="0" hostname="evolus-50b0002c" name="liningtest.WarmTests" tests="1" time="0.062" timestamp="2010-12-16T04:07:47"> <properties /> <testcase classname="liningtest.WarmTests" name="testSomething" time="0.062"> <error message="No signature of method: liningtest.Warm.hasErrors() is applicable for argument types: () values: [] Possible solutions: hashCode()" type="groovy.lang.MissingMethodException">groovy.lang.MissingMethodException: No signature of method: liningtest.Warm.hasErrors() is applicable for argument types: () values: [] Possible solutions: hashCode() at liningtest.WarmTests.testSomething(WarmTests.groovy:18) </error> </testcase> <system-out><![CDATA[--Output from testSomething-- ]]></system-out> <system-err><![CDATA[--Output from testSomething-- ]]></system-err> </testsuite> UPDATE 2: When I don't use Unit test, but try to call hasErrors in the controller, it runs but return false value. (hasErrors return false with Warm('Hihi', 3) ). Does anyone has a clue?

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  • Dealing with external processes

    - by Jesse Aldridge
    I've been working on a gui app that needs to manage external processes. Working with external processes leads to a lot of issues that can make a programmer's life difficult. I feel like maintenence on this app is taking an unacceptably long time. I've been trying to list the things that make working with external processes difficult so that I can come up with ways of mitigating the pain. This kind of turned into a rant which I thought I'd post here in order to get some feedback and to provide some guidance to anybody thinking about sailing into these very murky waters. Here's what I've got so far: Output from the child can get mixed up with output from the parent. This can make both outputs misleading and hard to read. It can be hard to tell what came from where. It becomes harder to figure out what's going on when things are asynchronous. Here's a contrived example: import textwrap, os, time from subprocess import Popen test_path = 'test_file.py' with open(test_path, 'w') as file: file.write(textwrap.dedent(''' import time for i in range(3): print 'Hello %i' % i time.sleep(1)''')) proc = Popen('python -B "%s"' % test_path) for i in range(3): print 'Hello %i' % i time.sleep(1) os.remove(test_path) I guess I could have the child process write its output to a file. But it can be annoying to have to open up a file every time I want to see the result of a print statement. If I have code for the child process I could add a label, something like print 'child: Hello %i', but it can be annoying to do that for every print. And it adds some noise to the output. And of course I can't do it if I don't have access to the code. I could manually manage the process output. But then you open up a huge can of worms with threads and polling and stuff like that. A simple solution is to treat processes like synchronous functions, that is, no further code executes until the process completes. In other words, make the process block. But that doesn't work if you're building a gui app. Which brings me to the next problem... Blocking processes cause the gui to become unresponsive. import textwrap, sys, os from subprocess import Popen from PyQt4.QtGui import * from PyQt4.QtCore import * test_path = 'test_file.py' with open(test_path, 'w') as file: file.write(textwrap.dedent(''' import time for i in range(3): print 'Hello %i' % i time.sleep(1)''')) app = QApplication(sys.argv) button = QPushButton('Launch process') def launch_proc(): # Can't move the window until process completes proc = Popen('python -B "%s"' % test_path) proc.communicate() button.connect(button, SIGNAL('clicked()'), launch_proc) button.show() app.exec_() os.remove(test_path) Qt provides a process wrapper of its own called QProcess which can help with this. You can connect functions to signals to capture output relatively easily. This is what I'm currently using. But I'm finding that all these signals behave suspiciously like goto statements and can lead to spaghetti code. I think I want to get sort-of blocking behavior by having the 'finished' signal from QProcess call a function containing all the code that comes after the process call. I think that should work but I'm still a bit fuzzy on the details... Stack traces get interrupted when you go from the child process back to the parent process. If a normal function screws up, you get a nice complete stack trace with filenames and line numbers. If a subprocess screws up, you'll be lucky if you get any output at all. You end up having to do a lot more detective work everytime something goes wrong. Speaking of which, output has a way of disappearing when dealing external processes. Like if you run something via the windows 'cmd' command, the console will pop up, execute the code, and then disappear before you have a chance to see the output. You have to pass the /k flag to make it stick around. Similar issues seem to crop up all the time. I suppose both problems 3 and 4 have the same root cause: no exception handling. Exception handling is meant to be used with functions, it doesn't work with processes. Maybe there's some way to get something like exception handling for processes? I guess that's what stderr is for? But dealing with two different streams can be annoying in itself. Maybe I should look into this more... Processes can hang and stick around in the background without you realizing it. So you end up yelling at your computer cuz it's going so slow until you finally bring up your task manager and see 30 instances of the same process hanging out in the background. Also, hanging background processes can interefere with other instances of the process in various fun ways, such as causing permissions errors by holding a handle to a file or someting like that. It seems like an easy solution to this would be to have the parent process kill the child process on exit if the child process didn't close itself. But if the parent process crashes, cleanup code might not get called and the child can be left hanging. Also, if the parent waits for the child to complete, and the child is in an infinite loop or something, you can end up with two hanging processes. This problem can tie in to problem 2 for extra fun, causing your gui to stop responding entirely and force you to kill everything with the task manager. F***ing quotes Parameters often need to be passed to processes. This is a headache in itself. Especially if you're dealing with file paths. Say... 'C:/My Documents/whatever/'. If you don't have quotes, the string will often be split at the space and interpreted as two arguments. If you need nested quotes you can use ' and ". But if you need to use more than two layers of quotes, you have to do some nasty escaping, for example: "cmd /k 'python \'path 1\' \'path 2\''". A good solution to this problem is passing parameters as a list rather than as a single string. Subprocess allows you to do this. Can't easily return data from a subprocess. You can use stdout of course. But what if you want to throw a print in there for debugging purposes? That's gonna screw up the parent if it's expecting output formatted a certain way. In functions you can print one string and return another and everything works just fine. Obscure command-line flags and a crappy terminal based help system. These are problems I often run into when using os level apps. Like the /k flag I mentioned, for holding a cmd window open, who's idea was that? Unix apps don't tend to be much friendlier in this regard. Hopefully you can use google or StackOverflow to find the answer you need. But if not, you've got a lot of boring reading and frusterating trial and error to do. External factors. This one's kind of fuzzy. But when you leave the relatively sheltered harbor of your own scripts to deal with external processes you find yourself having to deal with the "outside world" to a much greater extent. And that's a scary place. All sorts of things can go wrong. Just to give a random example: the cwd in which a process is run can modify it's behavior. There are probably other issues, but those are the ones I've written down so far. Any other snags you'd like to add? Any suggestions for dealing with these problems?

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  • URL load error during adding

    - by Steven
    hi, i have a string say Path ="C:\AAA\bin" which is a path to a project's bin folder. I used new URL(Path) during invocation of addURL method of URLClassLoader class. ex- addURL(sysLoader,new URL(Path)) ; its giving unknown protocol:c exception whats the problem?Help

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