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  • How can i iterate through QListWidget items and work with each item?

    - by Hossein
    In CSharp its as simple as writting : listBox1.Items.Add("Hello"); listBox1.Items.Add("There"); foreach (string item in listBox1.Items ) { MessageBox.Show(item.ToString()); } and i can easily add different objects to a list box and then retrieve them using foreach. I tried the same approach in Qt 4.8.2 but it seems they are different.though they look very similar at first.I found that Qt supports foreach so i went on and tried something like : foreach(QListWidgetItem& item,ui->listWidget->items()) { item.setTextColor(QColor::blue()); } which failed clearly.It says the items() needs a parameter which confuses me.I am trying to iterate through the ListBox itself, so what does this mean? I tried passing the ListBox object as the parameter itself this again failed too: foreach(QListWidgetItem& item,ui->listWidget->items(ui->listWidget)) { item.setTextColor(QColor::blue()); } So here are my questions: How can I iterate through a QListWidget items in Qt? Can i store objects as items in QListWidgets like C#? How can i convert an object in QListWidgets to string(C#s ToString counter part in Qt) ? (suppose i want to use a QMessagBox instead of that setTextColor and want to print out all string items in the QlistWidget.)

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  • Deserialize json with json.net c#

    - by 76mel
    Hi, am new to Json so a little green. I have a Rest Based Service that returns a json string; {"treeNode":[{"id":"U-2905","pid":"R","userId":"2905"}, {"id":"U-2905","pid":"R","userId":"2905"}]} I have been playing with the Json.net and trying to Deserialize the string into Objects etc. I wrote an extention method to help. public static T DeserializeFromJSON<T>(this Stream jsonStream, Type objectType) { T result; using (StreamReader reader = new StreamReader(jsonStream)) { JsonSerializer serializer = new JsonSerializer(); try { result = (T)serializer.Deserialize(reader, objectType); } catch (Exception e) { throw; } } return result; } I was expecting an array of treeNode[] objects. But its seems that I can only deserialize correctly if treeNode[] property of another object. public class treeNode { public string id { get; set; } public string pid { get; set; } public string userId { get; set; } } I there a way to to just get an straight array from the deserialization ? Cheers

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  • Static Variables somehow maintaining state?

    - by gfoley
    I am working on an existing project, setup by another coder. I'm having some trouble understanding how state is being maintained between pages. There is a Class library which has some helper objects. Mostly these objects are just used for there static methods and rarely instantiated or inherited. This is an example class I'm testing with. public sealed class Application { public static string Test; } Now when i run something like the following in the base class of my page, I would expect the result to be "1: 2:Test" all the time (note that "1" is empty), but strangly its only this way the first time it is run. Then every time afterwards its "1:Test 2:Test". Somehow its maintaining the state of the static variable between pages and being refreshed?? Response.Write("1:" + SharedLibrary.Application.Test); SharedLibrary.Application.Test = "Test"; Response.Write(" 2:" + SharedLibrary.Application.Test); I need to create more classes like this, but want to understand why this is occurring in the first place. Many Thanks

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  • Style first 2 TextViews in Android ListView differently

    - by Kurtis Nusbaum
    I have a ListView and I want the first two entries in it to be displayed differently than the rest. Nothing fancy, I want them all to just be text views. But the first two entries need to have different sizes and weights than the rest. I tried modifying the ArrayAdapter class like so: private class BusStopAdapter<T> extends ArrayAdapter<T>{ public BusStopAdapter( Context context, int textViewResourceId, List<T> objects) { super(context, textViewResourceId, objects); } public View getView(int position, View convertView, ViewGroup parent) { TextView toReturn = (TextView)super.getView(position, convertView, parent); if(position == 0){ toReturn.setTextSize(12); toReturn.setText("Previous Bus: " + toReturn.getText()); toReturn.setPadding(0,0,0,0); } else if(position == 1){ toReturn.setTextSize(20); toReturn.setPadding( toReturn.getPaddingLeft(), 0, toReturn.getPaddingRight(), 0 ); toReturn.setText("Next Bus: " + toReturn.getText()); toReturn.setGravity(Gravity.CENTER_HORIZONTAL|Gravity.TOP); } return toReturn; } } But this inadvertantly causes some of the other textviews to take on these special attributes. I think it's because cause textviews get "recycled" in the AbsListAdapter class.

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  • C++ Builder 2010 Exception Dead Lock ???

    - by James
    Hello Is this some kind of exception dead lock i am facing? How to avoid it ? Have a look at below line where i have TIdContext objects of connected clients stored in an objlist and at times i need to process it. But if one user is disconnected while another thread is processing the list, then for that freed TIdContext-Data object I am getting Access voilation, Ok its fine i am using try/catch but problem is that at below line there is some kind of dead lock and process hangs , if i attach a debuger it show Access voilation Again and Again and Again, and cpu coonsumption goes up because of that exception dead lock. AnsiString UserID = ((Tmyobject*) ((TIdContext*) ObjList->Objects[i])->Data)->UserID; i know i can check before accessing the object, if object is not Null, It works.. But my question is what if once in a blue moon the Data object is freed at the point when NULL check is performed and on next line when again i am accessing the object i get same dead lock ??? So how to avoid/handle this dead lock exception ? Here is the call stack... :005F07C0 System::AnsiStringBase::AnsiStringBase(this=:0285FCE0, src=????) :0040223F System::AnsiStringT<0>::AnsiStringT<0>(this=:0285FCE0, src=:00000008) :00457996 TSomeClass::SomeFunction(this=:009D8230, UserID={ }, DataSize={ }, ) :0047BFF1 __linkproc__ ThreadProc(Thread=:009561C0) :004AD00E __linkproc__ ThreadWrapper(Parameter=:009EAA30) :7c80b729 ; C:\WINDOWS\system32\kernel32.dll Please helppppppppppppppppppppp Thanks

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  • Windows 7 versus Windows XP multithreading - Delphi app not acting right

    - by Robert Oschler
    I'm having a problem with a Delphi Pro 6 application that I wrote on my Windows XP machine when it runs on Windows 7. I don't have Windows 7 to test yet and I'm trying to see if Windows 7 might be the source of the trouble. Is there a fundamental difference between the way Windows 7 handles threads compared to Windows XP? I am seeing things happen out of sequence in my error logs on Windows 7 and it's causing problems. For example, objects that should have been initialized are uninitialized when running on Windows 7, yet those objects are initialized on Windows XP by the time they are needed. Some questions: 1) Are there any core differences that could cause threads/processes to behave differently between the two operating system versions? 2) I know this next question may seem absurd, but does Windows 7 attempt to split/fork threads that aren't split/forked on Windows XP? 3) And lastly, are there any known issues with FPU handling that can cause XP programs trouble when run on Windows 7 due to operational differences in wait state handling or register storage, or perhaps something like Exception mask settings, etc? 4) Any 32-bit versus 64-bit issues that could be creating trouble here? -- roschler

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  • Optimizing a bin-placement algorithm

    - by user258651
    Alright, I've got two collections, and I need to place elements from collection1 into the bins (elements) of collection2, based on whether their value falls within a given bin's range. For a concrete example, assume I have a sorted collection objects (bins) which have an int range ([1...4], [5..10], etc). I need to determine the range an int falls in, and place it in the appropriate bin. foreach(element n in collection1) { foreach(bin m in collection2) { if (m.inRange(n)) { m.add(n); break; } } } So the obvious NxM complexity algorithm is there, but I really would like to see Nxlog(M). To do this I'd like to use BinarySearch in place of the inner foreach loop. To use BinarySearch, I need to implement an IComparer class to do the searching for me. The problem I'm running into is this approach would require me to make an IComparer.Compare function that compares two different types of objects (an element to its bin), and that doesn't seem possible or correct. So I'm asking, how should I write this algorithm?

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  • How to provide an inline model field with a queryset choices without losing field value for inline r

    - by Judith Boonstra
    The code displayed below is providing the choices I need for the app field, and the choices I need for the attr field when using Admin. I am having a problem with the attr field on the inline form for already saved records. The attr selected for these saved does show in small print above the field, but not within the field itself. # MODELS: Class Vocab(models.Model): entity = models.Charfield, max_length = 40, unique = True) Class App(models.Model): name = models.ForeignKey(Vocab, related_name = 'vocab_appname', unique = True) app = SelfForeignKey('self, verbose_name = 'parent', blank = True, null = True) attr = models.ManyToManyField(Vocab, related_name = 'vocab_appattr', through ='AppAttr' def parqs(self): a method that provides a queryset consisting of available apps from vocab, excluding self and any apps within the current app's dependent line. def attrqs(self): a method that provides a queryset consisting of available attr from vocab excluding those already selected by current app, 2) those already selected by any apps within the current app's parent line, and 3) those selected by any apps within the current app's dependent line. Class AppAttr(models.Model): app = models.ForeignKey(App) attr = models.ForeignKey(Vocab) # FORMS: from models import AppAttr def appattr_form_callback(instance, field, *args, **kwargs) if field.name = 'attr': if instance: return field.formfield(queryset = instance.attrqs(), *kwargs) return field.formfield(*kwargs) # ADMIN: necessary imports class AppAttrInline(admin.TabularInline): model = AppAttr def get_formset(self, request, obj = None, **kwargs): kwargs['formfield_callback'] = curry(appattr_form_callback, obj) return super(AppAttrInline, self).get_formset(request, obj, **kwargs) class AppForm(forms.ModelForm): class Meta: model = App def __init__(self, *args, **kwargs): super(AppForm, self).__init__(*args, **kwargs) if self.instance.id is None: working = App.objects.all() else: thisrec = App.objects.get(id = self.instance.id) working = thisrec.parqs() self.fields['par'].queryset = working class AppAdmin(admin.ModelAdmin): form = AppForm inlines = [AppAttrInline,] fieldsets = .......... necessary register statements

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  • Should I invest in GraniteDS for Flex + Java development?

    - by Boden
    I'm new to Flex development, and RIAs in general. I've got a CRUD-style Java + Spring + Hibernate service on top of which I'm writing a Flex UI. Currently I'm using BlazeDS. This is an internal application running on a local network. It's become apparent to me that the way RIAs work is more similar to a desktop application than a web application in that we load up the entire model and work with it directly on the client (or at least the portion that we're interested in). This doesn't really jive well with BlazeDS because really it only supports remoting and not data management, thus it can become a lot of extra work to make sure that clients are in sync and to avoid reloading the model which can be large (especially since lazy loading is not possible). So it feels like what I'm left with is a situation where I have to treat my Flex application more like a regular old web application where I do a lot of fine grained loading of data. LiveCycle is too expensive. The free version of WebOrb for Java really only does remoting. Enter GraniteDS. As far as I can determine, it's the only free solution out there that has many of the data management features of LiveCycle. I've started to go through its documentation a bit and suddenly feel like it's yet another quagmire of framework that I'll have to learn just to get an application running. So my question(s) to the StackOverflow audience is: 1) do you recommend GraniteDS, especially if my current Java stack is Spring + Hibernate? 2) at what point do you feel like it starts to pay off? That is, at what level of application complexity do you feel that using GraniteDS really starts to make development that much better? In what ways?

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  • "no inclosing instance error " while getting top term frequencies for document from Lucene index

    - by Julia
    Hello ! I am trying to get the most occurring term frequencies for every particular document in Lucene index. I am trying to set the treshold of top occuring terms that I care about, maybe 20 However, I am getting the "no inclosing instance of type DisplayTermVectors is accessible" when calling Comparator... So to this function I pass vector of every document and max top terms i would like to know protected static Collection getTopTerms(TermFreqVector tfv, int maxTerms){ String[] terms = tfv.getTerms(); int[] tFreqs = tfv.getTermFrequencies(); List result = new ArrayList(terms.length); for (int i = 0; i < tFreqs.length; i++) { TermFrq tf = new TermFrq(terms[i], tFreqs[i]); result.add(tf); } Collections.sort(result, new FreqComparator()); if(maxTerms < result.size()){ result = result.subList(0, maxTerms); } return result; } /Class for objects to hold the term/freq pairs/ static class TermFrq{ private String term; private int freq; public TermFrq(String term,int freq){ this.term = term; this.freq = freq; } public String getTerm(){ return this.term; } public int getFreq(){ return this.freq; } } /*Comparator to compare the objects by the frequency*/ class FreqComparator implements Comparator{ public int compare(Object pair1, Object pair2){ int f1 = ((TermFrq)pair1).getFreq(); int f2 = ((TermFrq)pair2).getFreq(); if(f1 > f2) return 1; else if(f1 < f2) return -1; else return 0; } } Explanations and corrections i will very much appreciate, and also if someone else had experience with term frequency extraction and did it better way, I am opened to all suggestions! Please help!!!! Thanx!

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  • Animate and form rows, arrays, AS3

    - by VideoDnd
    Question How can I animate and form rows together? Explanation One 'for loop' is for animation, the other 'for loop' is for making rows. I want to understand how to use arrays and create a row of sprite animations. 'for loop' for animation //FRAMES ARRAY //THIS SETS UP MY ANIMATION FOR TIMER EVENT var frames:Array = [ new Frame1(), new Frame2(), new Frame3(), new Frame4(), new Frame5(), new Frame6(), new Frame7(), new Frame8(), new Frame9(), new Frame0(), ]; for each (var frame:Sprite in frames) { addChild(frame); } 'for loop' for rows //THIS MAKES A ROW OF DISPLAY OBJECTS var numberOfClips:Number = 11; var xStart:Number = 0; var yStart:Number = 0; var xVal:Number = xStart; var xOffset:Number = 2; for (var $:Number=0; $<numberOfClips; $++) { //DUDE ARRAY var dude:Array = frames; dude.y = yStart +11; dude.x = xVal +55; xVal = dude.x + dude.width + this.xOffset; } timer var timer:Timer = new Timer(100); timer.addEventListener(TimerEvent.TIMER, countdown); function countdown(event:TimerEvent) { var currentFrame:int = timer.currentCount % frames.length; for (var i:int = 0; i < frames.length; ++i) { frames[i].visible = (i == currentFrame); } } timer.start(); counter experiment My new class I'm working on loops through 10 different display objects that are numbers. For those following, I'm trying to make something like NumbersView.

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  • STL vector performance

    - by iAdam
    STL vector class stores a copy of the object using copy constructor each time I call push_back. Wouldn't it slow down the program? I can have a custom linkedlist kind of class which deals with pointers to objects. Though it would not have some benefits of STL but still should be faster. See this code below: #include <vector> #include <iostream> #include <cstring> using namespace std; class myclass { public: char* text; myclass(const char* val) { text = new char[10]; strcpy(text, val); } myclass(const myclass& v) { cout << "copy\n"; //copy data } }; int main() { vector<myclass> list; myclass m1("first"); myclass m2("second"); cout << "adding first..."; list.push_back(m1); cout << "adding second..."; list.push_back(m2); cout << "returning..."; myclass& ret1 = list.at(0); cout << ret1.text << endl; return 0; } its output comes out as: adding first...copy adding second...copy copy The output shows the copy constructor is called both times when adding and when retrieving the value even then. Does it have any effect on performance esp when we have larger objects?

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  • Are there any downsides in using C++ for network daemons?

    - by badcat
    Hey guys! I've been writing a number of network daemons in different languages over the past years, and now I'm about to start a new project which requires a new custom implementation of a properitary network protocol. The said protocol is pretty simple - some basic JSON formatted messages which are transmitted in some basic frame wrapping to have clients know that a message arrived completely and is ready to be parsed. The daemon will need to handle a number of connections (about 200 at the same time) and do some management of them and pass messages along, like in a chat room. In the past I've been using mostly C++ to write my daemons. Often with the Qt4 framework (the network parts, not the GUI parts!), because that's what I also used for the rest of the projects and it was simple to do and very portable. This usually worked just fine, and I didn't have much trouble. Being a Linux administrator for a good while now, I noticed that most of the network daemons in the wild are written in plain C (of course some are written in other languages, too, but I get the feeling that 80% of the daemons are written in plain C). Now I wonder why that is. Is this due to a pure historic UNIX background (like KISS) or for plain portability or reduction of bloat? What are the reasons to not use C++ or any "higher level" languages for things like daemons? Thanks in advance! Update 1: For me using C++ usually is more convenient because of the fact that I have objects which have getter and setter methods and such. Plain C's "context" objects can be a real pain at some point - especially when you are used to object oriented programming. Yes, I'm aware that C++ is a superset of C, and that C code is basically C++. But that's not the point. ;)

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  • object / class methods serialized as well?

    - by Mat90
    I know that data members are saved to disk but I was wondering whether object's/class' methods are saved in binary format as well? Because I found some contradictionary info, for example: Ivor Horton: "Class objects contain function members as well as data members, and all the members, both data and functions, have access specifiers; therefore, to record objects in an external file, the information written to the file must contain complete specifications of all the class structures involved." and: Are methods also serialized along with the data members in .NET? Thus: are method's assembly instructions (opcodes and operands) stored to disk as well? Just like a precompiled LIB or DLL? During the DOS ages I used assembly so now and then. As far as I remember from Delphi and the following site (answer by dan04): Are methods also serialized along with the data members in .NET? sizeof(<OBJECT or CLASS>) will give the size of all data members together (no methods/procedures). Also a nice C example is given there with data and members declared in one class/struct but at runtime these methods are separate procedures acting on a struct of data. However, I think that later class/object implementations like Pascal's VMT may be different in memory.

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  • python os.mkfifo() for Windows

    - by user302099
    Hello. Short version (if you can answer the short version it does the job for me, the rest is mainly for the benefit of other people with a similar task): In python in Windows, I want to create 2 file objects, attached to the same file (it doesn't have to be an actual file on the hard-drive), one for reading and one for writing, such that if the reading end tries to read it will never get EOF (it will just block until something is written). I think in linux os.mkfifo() would do the job, but in Windows it doesn't exist. What can be done? (I must use file-objects). Some extra details: I have a python module (not written by me) that plays a certain game through stdin and stdout (using raw_input() and print). I also have a Windows executable playing the same game, through stdin and stdout as well. I want to make them play one against the other, and log all their communication. Here's the code I can write (the get_fifo() function is not implemented, because that's what I don't know to do it Windows): class Pusher(Thread): def __init__(self, source, dest, p1, name): Thread.__init__(self) self.source = source self.dest = dest self.name = name self.p1 = p1 def run(self): while (self.p1.poll()==None) and\ (not self.source.closed) and (not self.source.closed): line = self.source.readline() logging.info('%s: %s' % (self.name, line[:-1])) self.dest.write(line) self.dest.flush() exe_to_pythonmodule_reader, exe_to_pythonmodule_writer =\ get_fifo() pythonmodule_to_exe_reader, pythonmodule_to_exe_writer =\ get_fifo() p1 = subprocess.Popen(exe, shell=False, stdin=subprocess.PIPE, stdout=subprocess.PIPE) old_stdin = sys.stdin old_stdout = sys.stdout sys.stdin = exe_to_pythonmodule_reader sys.stdout = pythonmodule_to_exe_writer push1 = Pusher(p1.stdout, exe_to_pythonmodule_writer, p1, '1') push2 = Pusher(pythonmodule_to_exe_reader, p1.stdin, p1, '2') push1.start() push2.start() ret = pythonmodule.play() sys.stdin = old_stdin sys.stdout = old_stdout

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  • How to catch non exist requested URL in Java servlet ?

    - by Frank
    My objects are stored online in two different places : <1 On my nmjava.com site, where I can put them in a directory called "Dir_My_App/Dir_ABC/" <2 On Google App Engine datastore When my Java app runs it checks both places for the objects, I designed the app so that it tries to get an object from a Url, it doesn't care whether it's an object in a directory or an object returned by a servlet. My_Object Get_Object(String Site_Url,String Object_Path) { ... get object by the name of Object_Path from the Site_Url ... } Now the request Url for my web site nmjava.com might look like this : http://nmjava.com/Dir_My_App/Dir_ABC/My_Obj_123 [ In a directory ] Or in the case of Google App Engine servlet : http://nm-java.appspot.com/Check_License/Dir_My_App/Dir_ABC/My_Obj_123 [ Non exist ] The "Object_Path" was generated by my app automatically. It can now get the object from my site by the above method like this : My_Object Get_Object("http://nmjava.com","/Dir_My_App/Dir_ABC/My_Obj_123"); In the Google App Engine, my servlet is running and ready to serve the object, if the request comes in correctly, but since I don't want to design my app to know whether the object is in one site's directory or in other site's datastore, I need to design the servlet to catch the non exist Url, such as the one above, and be able to make a call : My_Object Get_Object("http://nm-java.appspot.com/Check_License","/Dir_My_App/Dir_ABC/My_Obj_123"); So my question is : When a request comes into the servlet with a non exist Url, how should it catch it and analyze the url in order to respond properly, in my case it should know that : http://nm-java.appspot.com/Check_License/Dir_My_App/Dir_ABC/My_Obj_123 is asking for the object "My_Obj_123" [ ignore the dirs ] and return the object from the datastore. Now I'm getting this : Error: Not Found The requested URL /Check_License/Dir_My_App/Dir_ABC/My_Obj_123 was not found on this server. Where in my servlet and how do I detect the request for this non exist Url ?

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  • Is MarshalByRefObject special?

    - by Vilx-
    .NET has a thing called remoting where you can pass objects around between separate appdomains or even physical machines. I don't fully understand how the magic is done, hence this question. In remoting there are two base ways of passing objects around - either they can be serialized (converted to a bunch of bytes and the rebuilt at the other end) or they can inherit from MarshalByRefObject, in which case .NET makes some transparent proxies and all method calls are forwarded back to the original instance. This is pretty cool and works like magic. And I don't like magic in programming. Looking at the MarshalByRefObject with the Reflector I don't see anything that would set it apart from any other typical object. Not even a weird internal attribute or anything. So how is the whole transparent proxy thing organized? Can I make such a mechanism myself? Can I make an alternate MyMarshalByRefObject which would not inherit from MarshalByRefObject but would still act the same? Or is MarshalByRefObject receiving some special treatment by the .NET engine itself and the whole remoting feat is non-duplicatable by mere mortals?

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  • Where are the network boundaries in the Java Connector Architecture (JCA)?

    - by Laird Nelson
    I am writing a JCA resource adapter. I'm also, as I go, trying to fully understand the connection management portion of the JCA specification. As a thought experiment, pretend that the only client of this adapter will be a Swing Java Application Client located on a different machine. Also assume that the resource adapter will communicate with its "enterprise information system" (EIS) over the network as well. As I understand the JCA specification, the .rar file is deployed to the application server. The application server creates the .rar file's implementation of the ManagedConnectionFactory interface. It then asks it to produce a connection factory, which is the opaque object that is deployed to JNDI for the user to use to obtain a connection to the resource. (In the case of JDBC, the connection factory is a javax.sql.DataSource.) It is a requirement that the connection factory retain a reference to the application-server-supplied ConnectionManager, which, in turn, is required to be Serializable. This makes sense--in order for the connection factory to be stored in JNDI, it must be serializable, and in order for it to keep a reference to the ConnectionManager, the ConnectionManager must also be serializable. So fine, this little object graph gets installed in the application client's JNDI tree. This is where I start to get queasy. Is the ConnectionManager--the piece supplied by the application server that is supposed to handle connection management, sharing, pooling, etc.--wholly present on the client at this point? One of its jobs is to create ManagedConnection instances, and a ManagedConnection is not required to be Serializable, and the user connection handles it vends are also not required to be Serializable. That suggests to me that the whole connection pooling machinery is shipped wholesale to the application client and stuffed into its JNDI tree. Does this all mean that JCA interactions from the client side bypass the server-side componentry of the application server? Where are the network boundaries in the JCA API?

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  • Which class should store the lookup table?

    - by max
    The world contains agents at different locations, with only a single agent at any location. Each agent knows where he's at, but I also need to quickly check if there's an agent at a given location. Hence, I also maintain a map from locations to agents. I have a problem deciding where this map belongs to: class World, class Agent (as a class attribute) or elsewhere. In the following I put the lookup table, agent_locations, in class World. But now agents have to call world.update_agent_location every time they move. This is very annoying; what if I decide later to track other things about the agents, apart from their locations - would I need to add calls back to the world object all across the Agent code? class World: def __init__(self, n_agents): # ... self.agents = {} self.agent_locations = {} for id in range(n_agents): x, y = self.find_location() agent = Agent(self,x,y) self.agents.append(agent) self.agent_locations[x,y] = agent def update_agent_location(self, agent, x, y): del self.agent_locations[agent.x, agent.y] self.agent_locations[x, y] = agent def update(self): # next step in the simulation for agent in self.agents: agent.update() # next step for this agent # ... class Agent: def __init__(self, world, x, y): self.world = world self.x, self.y = x, y def move(self, x1, y1): self.world.update_agent_location(self, x1, y1) self.x, self.y = x1, y1 def update(): # find a good location that is not occupied and move there for x, y in self.valid_locations(): if not self.location_is_good(x, y): continue if self.world.agent_locations[x, y]: # location occupied continue self.move(x, y) I can instead put agent_locations in class Agent as a class attribute. But that only works when I have a single World object. If I later decide to instantiate multiple World objects, the lookup tables would need to be world-specific. I am sure there's a better solution... EDIT: I added a few lines to the code to show how agent_locations is used. Note that it's only used from inside Agent objects, but I don't know if that would remain the case forever.

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  • Sync two SqlExpress using NHibernate

    - by Christian
    Hello, I am creating a simple project management system which uses NHibernate for object storage. The underlying database is SQL express (at least currently for development). The client runs on either the desktop or laptop. I know I could use web-services and store the DB only on the desktop, but this would force the desktop to be available all the time. I am currently thinking about duplicating the DB, having two instances with "different data". To clarify, we are not talking about a productive app here, its a prototype. One way to achieve this very simple would be the following process: Client: Check if desktop DB is available (through web service) Client: If yes, use desktop storage, no problem here Client: If not, use own DB as storage Client: Poll desktop regulary, as soon as it comes on, sync Client: Switch to desktop storage ... Desktop: Do not attempt any DB operation before checking for required sync Desktop: If sync needed, do it... My question is now, how would you sync? Assume 4 or 5 types of objects, all have GUID as identifiers. Would you always manually "lazy load" all objects of a certain type and feed them to the DB. Would you always drop the whole desktop DB in case the client DB may be newer and out of sync? Again, I want to stress out, I am not assuming any conflicts or stale data, I basically just want to "copy the whole DB from the client". Would you use NHibernate for this? Or would you separate the copy process? When I think about it, my questions comes down to this: Is there any function from NHibernate: SyncDBs_SourceWins_(SourceDB, TargetDB) Thanks for help, Chris

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  • What's the difference between DI and factory patterns?

    - by Anthony Short
    I have a class which depends on 3 classes, all 3 of which have other classes they rely on. Currently, I'm using a container class to build up all the required classes, inject them into one another and return the application. The simplified version of the container looks something like this: class Builder { private $_options; public function __construct($options) { $this->_options = $options; } public function build() { $cache = $this->getCache(); $response = $this->getResponse(); $engine = $this->getEngine(); return new Application($cache,$response,$engine); } public function getResponse() { $encoder = $this->getResponseEncoder(); $cache = $this->getResponseCache(); return new Response($encoder,$cache); } // Methods for building each object } I'm not sure if this would be classified as FactoryMethod or a DI Container. They both seem to solve the same problem in the same way - They build objects and inject dependencies. This container has some more complicated building methods, like loading observers and attaching them to observable objects. Should factories be doing all the building (loading extensions etc) and the DI container should use these factories to inject dependencies? That way the sub-packages, like Cache, Response etc, can each have their own specialised factories.

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  • Reflection for a Field going wrong

    - by TiGer
    Hi, I have been trying to use reflection for a specifiec Field in the android.os.build class, the MANUFACTURER field... I have tried by using this code : try { Class myBuildClass = android.os.Build.class; Field m1 = Build.class.getDeclaredField("MANUFACTURER"); validField = true; manufacturer = Build.MANUFACTURER; } catch(Exception ex) { manufacturer = Build.PRODUCT; System.err.println("getDeviceSpecifics, got an exception during getting Field : " + ex.toString()); } I am gettign the following errors : 06-01 11:26:37.639: WARN/dalvikvm(7342): VFY: unable to resolve static field 2 (MANUFACTURER) in Landroid/os/Build; 06-01 11:26:37.639: WARN/dalvikvm(7342): VFY: rejecting opcode 0x62 at 0x0048 06-01 11:26:37.639: WARN/dalvikvm(7342): VFY: rejected Lmobilaria/android/managementModule/Management;.getDeviceSpecifics ()V 06-01 11:26:37.639: WARN/dalvikvm(7342): Verifier rejected class Lmobilaria/android/managementModule/Management; And when debugging I noticed that InvocationtargetException is continuesly thrown, so I am guessing I haven't been implementing the whole Reflection principle correctly... Any idea where things are going wrong or otherwise on how to implement Refelction for a single Field correctly ?

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  • Django Aggregation Across Reverse Relationship

    - by Tom
    Given these two models: class Profile(models.Model): user = models.ForeignKey(User, unique=True, verbose_name=_('user')) about = models.TextField(_('about'), blank=True) zip = models.CharField(max_length=10, verbose_name='zip code', blank=True) website = models.URLField(_('website'), blank=True, verify_exists=False) class ProfileView(models.Model): profile = models.ForeignKey(Profile) viewer = models.ForeignKey(User, blank=True, null=True) created = models.DateTimeField(auto_now_add=True) I want to get all profiles sorted by total views. I can get a list of profile ids sorted by total views with: ProfileView.objects.values('profile').annotate(Count('profile')).order_by('-profile__count') But that's just a dictionary of profile ids, which means I then have to loop over it and put together a list of profile objects. Which is a number of additional queries and still doesn't result in a QuerySet. At that point, I might as well drop to raw SQL. Before I do, is there a way to do this from the Profile model? ProfileViews are related via a ForeignKey field, but it's not as though the Profile model knows that, so I'm not sure how to tie the two together. As an aside, I realize I could just store views as a property on the Profile model and that may turn out to be what I do here, but I'm still interested in learning how to better use the Aggregation functions.

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  • c++ struct size

    - by kiokko89
    struct CExample { int a; } int main(int argc, char* argv[]) { CExample ce; CExample ce2; cout << "Size:" << sizeof(ce)<< " Address: "<< &ce<< endl; cout << "Size:" << sizeof(ce2)<< " Address: "<< &ce2 << endl; CExample ceArr[2]; cout << "Size:" << sizeof(ceArr[0])<< " Address: "<<&ceArr[0]<<endl; cout << "Size:" << sizeof(ceArr[1])<< " Address: "<<&ceArr[1]<<endl; return 0; } Excuse me I'm just a beginner but i'd like to know why with this code, there is a difference of 12 bytes between the addresses of the first two objects(ce and ce2) (i thought about data allignment), but there is only a difference of 4 bytes between the two objects in the array. Sorry for my bad English...

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  • What should I do with an over-bloated select-box/drop-down

    - by Tristan Havelick
    All web developers run into this problem when the amount of data in their project grows, and I have yet to see a definitive, intuitive best practice for solving it. When you start a project, you often create forms with tags to help pick related objects for one-to-many relationships. For instance, I might have a system with Neighbors and each Neighbor belongs to a Neighborhood. In version 1 of the application I create an edit user form that has a drop down for selecting users, that simply lists the 5 possible neighborhoods in my geographically limited application. In the beginning, this works great. So long as I have maybe 100 records or less, my select box will load quickly, and be fairly easy to use. However, lets say my application takes off and goes national. Instead of 5 neighborhoods I have 10,000. Suddenly my little drop-down takes forever to load, and once it loads, its hard to find your neighborhood in the massive alphabetically sorted list. Now, in this particular situation, having hierarchical data, and letting users drill down using several dynamically generated drop downs would probably work okay. However, what is the best solution when the objects/records being selected are not hierarchical in nature? In the past, of done this with a popup with a search box, and a list, but this seems clunky and dated. In today's web 2.0 world, what is a good way to find one object amongst many for ones forms? I've considered using an Ajaxifed search box, but this seems to work best for free text, and falls apart a little when the data to be saved is just a reference to another object or record. Feel free to cite specific libraries with generic solutions to this problem, or simply share what you have done in your projects in a more general way

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