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  • Fixed point math in c#?

    - by x4000
    Hi there, I was wondering if anyone here knows of any good resources for fixed point math in c#? I've seen things like this (http://2ddev.72dpiarmy.com/viewtopic.php?id=156) and this (http://stackoverflow.com/questions/79677/whats-the-best-way-to-do-fixed-point-math), and a number of discussions about whether decimal is really fixed point or actually floating point (update: responders have confirmed that it's definitely floating point), but I haven't seen a solid C# library for things like calculating cosine and sine. My needs are simple -- I need the basic operators, plus cosine, sine, arctan2, PI... I think that's about it. Maybe sqrt. I'm programming a 2D RTS game, which I have largely working, but the unit movement when using floating-point math (doubles) has very small inaccuracies over time (10-30 minutes) across multiple machines, leading to desyncs. This is presently only between a 32 bit OS and a 64 bit OS, all the 32 bit machines seem to stay in sync without issue, which is what makes me think this is a floating point issue. I was aware from this as a possible issue from the outset, and so have limited my use of non-integer position math as much as possible, but for smooth diagonal movement at varying speeds I'm calculating the angle between points in radians, then getting the x and y components of movement with sin and cos. That's the main issue. I'm also doing some calculations for line segment intersections, line-circle intersections, circle-rect intersections, etc, that also probably need to move from floating-point to fixed-point to avoid cross-machine issues. If there's something open source in Java or VB or another comparable language, I could probably convert the code for my uses. The main priority for me is accuracy, although I'd like as little speed loss over present performance as possible. This whole fixed point math thing is very new to me, and I'm surprised by how little practical information on it there is on google -- most stuff seems to be either theory or dense C++ header files. Anything you could do to point me in the right direction is much appreciated; if I can get this working, I plan to open-source the math functions I put together so that there will be a resource for other C# programmers out there. UPDATE: I could definitely make a cosine/sine lookup table work for my purposes, but I don't think that would work for arctan2, since I'd need to generate a table with about 64,000x64,000 entries (yikes). If you know any programmatic explanations of efficient ways to calculate things like arctan2, that would be awesome. My math background is all right, but the advanced formulas and traditional math notation are very difficult for me to translate into code.

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  • boost::serialization of mutual pointers

    - by KneLL
    First, please take a look at these code: class Key; class Door; class Key { public: int id; Door *pDoor; Key() : id(0), pDoor(NULL) {} private: friend class boost::serialization::access; template <typename A> void serialize(A &ar, const unsigned int ver) { ar & BOOST_SERIALIZATION_NVP(id) & BOOST_SERIALIZATION_NVP(pDoor); } }; class Door { public: int id; Key *pKey; Door() : id(0), pKey(NULL) {} private: friend class boost::serialization::access; template <typename A> void serialize(A &ar, const unsigned int ver) { ar & BOOST_SERIALIZATION_NVP(id) & BOOST_SERIALIZATION_NVP(pKey); } }; BOOST_CLASS_TRACKING(Key, track_selectively); BOOST_CLASS_TRACKING(Door, track_selectively); int main() { Key k1, k_in; Door d1, d_in; k1.id = 1; d1.id = 2; k1.pDoor = &d1; d1.pKey = &k1; // Save data { wofstream f1("test.xml"); boost::archive::xml_woarchive ar1(f1); // !!!!! (1) const Key *pK = &k1; const Door *pD = &d1; ar1 << BOOST_SERIALIZATION_NVP(pK) << BOOST_SERIALIZATION_NVP(pD); } // Load data { wifstream i1("test.xml"); boost::archive::xml_wiarchive ar1(i1); // !!!!! (2) A *pK = &k_in; B *pD = &d_in; // (2.1) //ar1 >> BOOST_SERIALIZATION_NVP(k_in) >> BOOST_SERIALIZATION_NVP(d_in); // (2.2) ar1 >> BOOST_SERIALIZATION_NVP(pK) >> BOOST_SERIALIZATION_NVP(pD); } } The first (1) is a simple question - is it possible to pass objects to archive without pointers? If simply pass objects 'as is' that boost throws exception about duplicated pointers. But I'm confused of creating pointers to save objects. The second (2) is a real trouble. If comment out string after (2.1) then boost will corectly load a first Key object (and init internal Door pointer pDoor), but will not init a second Door (d_in) object. After this I have an inited *k_in* object with valid pointer to Door and empty *d_in* object. If use string (2.2) then boost will create two Key and Door objects somewhere in memory and save addresses in pointers. But I want to have two objects *k_in* and *d_in*. So, if I copy a values of memory objects to local variables then I store only addresses, for example, I can write code after (2.2): d_in.id = pD->id; d_in.pKey = pD->pKey; But in this case I store only a pointer and memory object remains in memory and I cannot delete it, because *d_in.pKey* will be unvalid. And I cannot perform a deep copy with operator=(), because if I write code like this: Key &operator==(const Key &k) { if (this != &k) { id = k.id; // call to Door::operator=() that calls *pKey = *d.pKey and so on *pDoor = *k.pDoor; } return *this; } then I will get a something like recursion of operator=()s of Key and Door. How to implement proper serialization of such pointers?

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  • StaleDataException: access closed cursor

    - by Aurora
    In my application, after enough clicking around, I get this error: 06-08 19:47:59.967: ERROR/AndroidRuntime(2429): java.lang.RuntimeException: Unable to pause activity {com.MYAPP.app/com.MYAPP.app.MainActivity}: android.database.StaleDataException: Access closed cursor What I have is a Tab Activity (my MainActivity), which has a ListActivity as the contents for each tab. Inside the onCreate for each ListActivity I get a cursor that represents the data to be displayed in that list. The onListItemClick for each list also creates another activity, so clicking on an item in the list will show more information about that item in a new screen. It's inconsistent, but after enough clicking into these new activities, or going back to the ListView from a new activity, the program crashes. In searching around for a solution to my problem, I did stumble upon registerDataSetObserver, but it doesn't seem to be the whole answer. I am also having trouble finding documentation on it, so I'm not sure I fully understand it. I have a custom ListAdapter that both my ListViews use and have called registerDataSetObservers on the cursors there. I have attached the relevant code from one of my ListActivities and from my custom ListAdapter class. The ListActivity. I have two of these, almost identical, except they both have different cursors created from different database queries: import com.MYAPP.app.listmanager.DeviceListAdapter; public class AllSensorsActivity extends ListActivity{ private DeviceListAdapter AllList; private DbManager db; protected Cursor AllCur; protected Cursor AllSensors; private static final String TAG = "AllSensorsActivity"; @Override public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); Log.e(TAG, "Calling All onCreate"); db = new DbManager(this); db.open(); AllCur = db.fetchAllDevices(); startManagingCursor(AllCur); AllSensors = db.fetchAllSensors(); startManagingCursor(AllSensors); AllList = new DeviceListAdapter(this, AllCur, AllSensors); setListAdapter(AllList); } @Override protected void onListItemClick(ListView l, View v, int position, long id){ String device_name = (String) ((DeviceListAdapter)getListAdapter()).getItem(position); String sensor_string = ((DeviceListAdapter)getListAdapter()).getSensors(id); Intent i = new Intent(this, SensorActivity.class); Bundle bundle = new Bundle(); bundle.putString("NAME", device_name); i.putExtras(bundle); bundle.putString("SENSORS", sensor_string); i.putExtras(bundle); this.startActivity(i); } The custom ListAdapter: public class DeviceListAdapter extends BaseAdapter { private static final String TAG = "DeviceListAdapter"; private Context mContext; private Cursor mSensors; private Cursor mDevices; protected MyDataSetObserver sensors_observer; protected MyDataSetObserver devices_observer; public DeviceListAdapter(Context context, Cursor devices, Cursor sensors){ mContext = context; mDevices = devices; mSensors = sensors; sensors_observer = new MyDataSetObserver(); mSensors.registerDataSetObserver(sensors_observer); devices_observer = new MyDataSetObserver(); mDevices.registerDataSetObserver(devices_observer); } // ... more functions and stuff that are not relevant go down here... } private class MyDataSetObserver extends DataSetObserver { public void onChanged(){ Log.e(TAG, "CHANGED CURSOR!"); } public void onInvalidated(){ Log.e(TAG, "INVALIDATED CURSOR!"); } } Should I just have MyDataSetObserver catch the exception and move on? I'd like a more robust solution than that if possible. Or is there some other way I could rearrange my program so that the staleDataException doesn't occur (as often)? I believe that it is happening because I am launching the new activity in my onListItemClick.

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  • Can LINQ-to-SQL omit unspecified columns on insert so a database default value is used?

    - by Todd Ropog
    I have a non-nullable database column which has a default value set. When inserting a row, sometimes a value is specified for the column, sometimes one is not. This works fine in TSQL when the column is omitted. For example, given the following table: CREATE TABLE [dbo].[Table1]( [id] [int] IDENTITY(1,1) NOT NULL, [col1] [nvarchar](50) NOT NULL, [col2] [nvarchar](50) NULL, CONSTRAINT [PK_Table1] PRIMARY KEY CLUSTERED ([id] ASC) ) GO ALTER TABLE [dbo].[Table1] ADD CONSTRAINT [DF_Table1_col1] DEFAULT ('DB default') FOR [col1] The following two statements will work: INSERT INTO Table1 (col1, col2) VALUES ('test value', '') INSERT INTO Table1 (col2) VALUES ('') In the second statement, the default value is used for col1. The problem I have is when using LINQ-to-SQL (L2S) with a table like this. I want to produce the same behavior, but I can't figure out how to make L2S do that. I want to be able to run the following code and have the first row get the value I specify and the second row get the default value from the database: var context = new DataClasses1DataContext(); var row1 = new Table1 { col1 = "test value", col2 = "" }; context.Table1s.InsertOnSubmit(row1); context.SubmitChanges(); var row2 = new Table1 { col2 = "" }; context.Table1s.InsertOnSubmit(row2); context.SubmitChanges(); If the Auto Generated Value property of col1 is False, the first row is created as desired, but the second row fails with a null error on col1. If Auto Generated Value is True, both rows are created with the default value from the database. I've tried various combinations of Auto Generated Value, Auto-Sync and Nullable, but nothing I've tried gives the behavior I want. L2S does not omit the column from the insert statement when no value is specified. Instead it does something like this: INSERT INTO Table1 (col1, col2) VALUES (null, '') ...which of course causes a null error on col1. Is there some way to get L2S to omit a column from the insert statement if no value is given? Or is there some other way to get the behavior I want? I need the default value at the database level because not all row inserts are done via L2S, and in some cases the default value is a little more complex than a hard coded value (e.g. creating the default based on another field) so I'd rather avoid duplicating that logic.

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  • Javascript childNodes does not find all children of a div when appendchild has been used

    - by yesterdayze
    Alright, I am hoping someone can help me out. I apologize up front that this one may be confusing. I have included an example to try to help ease the confusion as this is better seen then heard. I have created a webpage that contains a group or set of groups. Each group has a subgroup. In a nutshell what is happening is this page will allow me to combine multiple groups containing subgroups into a new group. The page will give the chance to rename the old subgroups before they are combined into new groups in order to avoid confusion. When a group is renamed it will check to make sure there is not already a group with that name. If there is it will copy itself out of it's own group and into that group and then delete the original. If the group does not already exist it will create that group, copy itself in and then delete the original. Subgroups can also be renamed at which point they will move into the group with the same name if it exists, or create a new one if it doesn't. The page has a main div. The main div contains 'new sub group' divs. Inside each of those is another div containing the 'old sub group' divs. I use a loop through the child nodes of the 'new sub group' div when renaming a group in order to find each child node. These are then copied into a new div within the main div. The crux of the problem is this. If I loop through a DIV and copy all of the DIVs in it into a new or existing DIV all is well. When I then try to take that DIV and copy all of it's DIVs into another or new DIV it always skips one of the moved DIVs. For simplicity I have copied the entire working code below. To recreate the issue click the spot where the image should appear next to the name ewrewrwe and rename it to something else. All is well. Now click that new group the same way and name it something else. You will see it skip one each time. I have linked the page here: http://vtbikenight.com/test.html The link is clean, it is my personal website I use for a local motorycle group I am part of. Thanks for the help everyone!!! Please let me know if I can clarify on anything. I know the code is not the best right now, it is just demo code and my intent is to get the concept working then streamline it all.

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  • Running an allocation simulation repeatedly breaks after the first run.

    - by Az
    Background I have a bunch of students, their desired projects and the supervisors for the respective projects. I'm running a battery of simulations to see which projects the students end up with, which will allow me to get some useful statistics required for feedback. So, this is essentially a Monte-Carlo simulation where I'm randomising the list of students and then iterating through it, allocating projects until I hit the end of the list. Then the process is repeated again. Note that, within a single session, after each successful allocation of a project the following take place: + the project is set to allocated and cannot be given to another student + the supervisor has a fixed quota of students he can supervise. This is decremented by 1 + Once the quota hits 0, all the projects from that supervisor become blocked and this has the same effect as a project being allocated Code def resetData(): for student in students.itervalues(): student.allocated_project = None for supervisor in supervisors.itervalues(): supervisor.quota = 0 for project in projects.itervalues(): project.allocated = False project.blocked = False The role of resetData() is to "reset" certain bits of the data. For example, when a project is successfully allocated, project.allocated for that project is flipped to True. While that's useful for a single run, for the next run I need to be deallocated. Above I'm iterating through thee three dictionaries - one each for students, projects and supervisors - where the information is stored. The next bit is the "Monte-Carlo" simulation for the allocation algorithm. sesh_id = 1 for trial in range(50): for id in randomiseStudents(1): stud_id = id student = students[id] if not student.preferences: # Ignoring the students who've not entered any preferences for rank in ranks: temp_proj = random.choice(list(student.preferences[rank])) if not (temp_proj.allocated or temp_proj.blocked): alloc_proj = student.allocated_proj_ref = temp_proj.proj_id alloc_proj_rank = student.allocated_rank = rank successActions(temp_proj) temp_alloc = Allocated(sesh_id, stud_id, alloc_proj, alloc_proj_rank) print temp_alloc # Explained break sesh_id += 1 resetData() # Refer to def resetData() above All randomiseStudents(1) does is randomise the order of students. Allocated is a class defined as such: class Allocated(object): def __init__(self, sesh_id, stud_id, alloc_proj, alloc_proj_rank): self.sesh_id = sesh_id self.stud_id = stud_id self.alloc_proj = alloc_proj self.alloc_proj_rank = alloc_proj_rank def __repr__(self): return str(self) def __str__(self): return "%s - Student: %s (Project: %s - Rank: %s)" %(self.sesh_id, self.stud_id, self.alloc_proj, self.alloc_proj_rank) Output and problem Now if I run this I get an output such as this (truncated): 1 - Student: 7720 (Project: 1100241 - Rank: 1) 1 - Student: 7832 (Project: 1100339 - Rank: 1) 1 - Student: 7743 (Project: 1100359 - Rank: 1) 1 - Student: 7820 (Project: 1100261 - Rank: 2) 1 - Student: 7829 (Project: 1100270 - Rank: 1) . . . 1 - Student: 7822 (Project: 1100280 - Rank: 1) 1 - Student: 7792 (Project: 1100141 - Rank: 7) 2 - Student: 7739 (Project: 1100267 - Rank: 1) 3 - Student: 7806 (Project: 1100272 - Rank: 1) . . . 45 - Student: 7806 (Project: 1100272 - Rank: 1) 46 - Student: 7714 (Project: 1100317 - Rank: 1) 47 - Student: 7930 (Project: 1100343 - Rank: 1) 48 - Student: 7757 (Project: 1100358 - Rank: 1) 49 - Student: 7759 (Project: 1100269 - Rank: 1) 50 - Student: 7778 (Project: 1100301 - Rank: 1) Basically, it works perfectly for the first run, but on subsequent runs leading upto the nth run, in this case 50, only a single student-project allocation pair is returned. Thus, the main issue I'm having trouble with is figuring out what is causing this anomalous behaviour especially since the first run works smoothly. Thanks in advance, Az

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  • PHP - static DB class vs DB singleton object

    - by Marco Demaio
    I don't want to create a discussion about singleton better than static or better than global, etc. I read dozens of questions about it on SO, but I couldn't come up with an answer to this SPECIFIC question, so I hope someone could now illuminate me buy answering this question with one (or more) real simple EXAMPLES, and not theoretical discussions. In my app I have the typical DB class needed to perform tasks on DB without having to write everywhere in code mysql_connect/mysql_select_db/mysql... (moreover in future I might decide to use another type of DB engine in place of mySQL so obviously I need a class of abstration). I could write the class either as a static class: class DB { private static $connection = FALSE; //connection to be opened //DB connection values private static $server = NULL; private static $usr = NULL; private static $psw = NULL; private static $name = NULL; public static function init($db_server, $db_usr, $db_psw, $db_name) { //simply stores connections values, withour opening connection } public static function query($query_string) { //performs query over alerady opened connection, if not open, it opens connection 1st } ... } or as a Singletonm class: class DBSingleton { private $inst = NULL; private $connection = FALSE; //connection to be opened //DB connection values private $server = NULL; private $usr = NULL; private $psw = NULL; private $name = NULL; public static function getInstance($db_server, $db_usr, $db_psw, $db_name) { //simply stores connections values, withour opening connection if($inst === NULL) $this->inst = new DBSingleton(); return $this->inst; } private __construct()... public function query($query_string) { //performs query over already opened connection, if connection is not open, it opens connection 1st } ... } Then after in my app if I wanto to query the DB i could do //Performing query using static DB object DB:init(HOST, USR, PSW, DB_NAME); DB::query("SELECT..."); //Performing query using DB singleton $temp = DBSingleton::getInstance(HOST, USR, PSW, DB_NAME); $temp->query("SELECT..."); My simple brain sees Singleton has got the only advantage to avoid declaring as 'static' each method of the class. I'm sure some of you could give me an EXAMPLE of real advantage of singleton in this specific case. Thanks in advance.

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  • WPF DataTemplateKey can not find ListBox key

    - by Ryan
    I am fairly new to WPF and am having trouble getting the DataTemplateKey to find my ListBox. <Window.Resources> <ControlTemplate x:Key="FocusTemplate" > <Rectangle Fill="Azure" Width="290" Height="55" /> </ControlTemplate> <Style x:Key="FocusStyle" TargetType="{x:Type Control}"> <Setter Property="Template" Value="{StaticResource FocusTemplate}"/> </Style> <Style TargetType="ListBoxItem"> <EventSetter Event="GotFocus" Handler="ListItem_GotFocus"></EventSetter> </Style> <DataTemplate DataType="{x:Type TextBlock}"> </DataTemplate> <DataTemplate x:Key="CustomListData" DataType="{x:Type ListBox}"> <Border BorderBrush="Black" BorderThickness="1" Margin="-2,0,0,-1"> <Grid> <Grid.RowDefinitions> <RowDefinition Height="55*" /> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto" /> <ColumnDefinition Width="*" /> </Grid.ColumnDefinitions> <Grid.RenderTransform> <TransformGroup> <ScaleTransform ScaleX="1" ScaleY="1"/> <SkewTransform AngleX="0" AngleY="0"/> <RotateTransform Angle="0"/> <TranslateTransform X="0" Y="0"/> </TransformGroup> </Grid.RenderTransform> <!--<ScrollViewer x:Name="PART_ContentHost" />--> <TextBox Width="290" TextAlignment="Left" VerticalContentAlignment="Center" BorderThickness="0" BorderBrush="Transparent" Foreground="#FF6FB8FD" FontSize="18" FocusVisualStyle="{StaticResource FocusStyle}" Name="editingBox" TextWrapping="Wrap" Text="{Binding .}" Grid.Column="1" Grid.Row="1" MinHeight="55" Cursor="Hand" IsReadOnly="True" > <TextBox.Background> <LinearGradientBrush EndPoint="0,1" StartPoint="0,0"> <LinearGradientBrush.RelativeTransform> <TransformGroup> <ScaleTransform CenterX="0.5" CenterY="0.5"/> <SkewTransform CenterX="0.5" CenterY="0.5"/> <RotateTransform Angle="0" CenterX="0.5" CenterY="0.5"/> <TranslateTransform/> </TransformGroup> </LinearGradientBrush.RelativeTransform> <GradientStop Color="#FF2D4984"/> <GradientStop Color="#FF182D56" Offset="0.042"/> </LinearGradientBrush> </TextBox.Background> </TextBox> </Grid> </Border> </DataTemplate> <Style TargetType="{x:Type ListBox}"> <Setter Property="ItemTemplate" Value="{StaticResource CustomListData }" /> <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled" /> </Style> </Window.Resources> <Window.DataContext> <ObjectDataProvider ObjectType="{x:Type local:ImageLoader}" MethodName="LoadImages" /> </Window.DataContext> <ListBox ItemsSource="{Binding}" Width="320" Background="#FF021422" BorderBrush="#FF1C4B79"> <ListBox.Resources> <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}">Transparent</SolidColorBrush> </ListBox.Resources> </ListBox> The following code will find a TextBlock var key = new System.Windows.DataTemplateKey(typeof(TextBlock)); var r = (DataTemplate)this.FindResource(key); However, when I change the type to ListBox, the key can not be found. What have I missed? Thanks Ryan

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  • How do I solve an unresolved external when using C++ Builder packages?

    - by David M
    I'm experimenting with reconfiguring my application to make heaving use of packages. Both I and another developer running a similar experiment are running into a bit of trouble when linking using several different packages. We're probably both doing something wrong, but goodness knows what :) The situation is this: The first package, PackageA.bpl, contains C++ class FooA. The class is declared with the PACKAGE directive. The second package, PackageB.bpl, contains a class inheriting from FooA, called FooB. It includes FooB.h, and the package is built using runtime packages, and links to PackageA by adding a reference to PackageA.bpi. When building PackageB, it compiles fine but linking fails with a number of unresolved externals, the first few of which are: [ILINK32 Error] Error: Unresolved external '__tpdsc__ FooA' referenced from C:\blah\FooB.OBJ [ILINK32 Error] Error: Unresolved external 'FooA::' referenced from C:\blah\FooB.OBJ [ILINK32 Error] Error: Unresolved external '__fastcall FooA::~FooA()' referenced from blah\FooB.OBJ etc. Running TDump on PackageA.bpl shows: Exports from PackageA.bpl 14 exported name(s), 14 export addresse(s). Ordinal base is 1. Sorted by Name: RVA Ord. Hint Name -------- ---- ---- ---- 00002A0C 8 0000 __tpdsc__ FooA 00002AD8 10 0001 __linkproc__ FooA::Finalize 00002AC8 9 0002 __linkproc__ FooA::Initialize 00002E4C 12 0003 __linkproc__ PackageA::Finalize 00002E3C 11 0004 __linkproc__ PackageA::Initialize 00006510 14 0007 FooA:: 00002860 5 0008 FooA::FooA(FooA&) 000027E4 4 0009 FooA::FooA() 00002770 3 000A __fastcall FooA::~FooA() 000028DC 6 000B __fastcall FooA::Method1() const 000028F4 7 000C __fastcall FooA::Method2() const 00001375 2 000D Finalize 00001368 1 000E Initialize 0000610C 13 000F ___CPPdebugHook So the class definitely seems to be exported and available to link. I can see entries for the specific things ILink32 says it's looking for and not finding. Running TDump on the BPI file shows similar entries. Other info The class does descend from TObject, though originally before refactoring into packages it was a normal C++ class. (More detail below. It seems "safer" using VCL-style classes when trying to solve problems with a very Delphi-ish thing like this anyway. Changing this only changes the order of unresolved externals to first not find Method1 and Method2, then others.) Declaration for FooA: class PACKAGE FooA: public TObject { public: FooA(); virtual __fastcall ~FooA(); FooA(const FooA&); virtual __fastcall long Method1() const; virtual __fastcall long Method2() const; }; and FooB: class FooB: public FooA { public: FooB(); virtual __fastcall ~FooB(); ... other methods... }; All methods definitely are implemented in the .cpp files, so it's not not finding them because they don't exist! The .cpp files also contain #pragma package(smart_init) near the top, under the includes. Questions that might help... Are packages reliable using C++, or are they only useable with Delphi code? Is linking to the first package by adding a reference to its BPI correct - is that how you're supposed to do it? I could use a LIB but it seems to make the second package much larger, and I suspect it's statically linking in the contents of the first. Can we use the PACKAGE directive only on TObject-derived classes? There is no compiler warning using it on standard C++ classes. Is splitting code into packages the best way to achieve the goal of isolating code and communicating through defined layers / interfaces? I've been investigating this path because it seems to be the C++Builder / Delphi Way, and if it worked it looks attractive. But are there better alternatives? I'm very new to using packages and have only known about them through using components before. Any general words of advice would be great! We're using C++Builder 2010. I've fabricated the class and method names in the above code examples, but other than that the details are exactly what we're seeing. Cheers, David

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  • How to represent different entities that have identical behavior?

    - by Dominik
    I have several different entities in my domain model (animal species, let's say), which have a few properties each. The entities are readonly (they do not change state during the application lifetime) and they have identical behavior (the differ only by the values of properties). How to implement such entities in code? Unsuccessful attempts: Enums I tried an enum like this: enum Animals { Frog, Duck, Otter, Fish } And other pieces of code would switch on the enum. However, this leads to ugly switching code, scattering the logic around and problems with comboboxes. There's no pretty way to list all possible Animals. Serialization works great though. Subclasses I also thought about where each animal type is a subclass of a common base abstract class. The implementation of Swim() is the same for all Animals, though, so it makes little sense and serializability is a big issue now. Since we represent an animal type (species, if you will), there should be one instance of the subclass per application, which is hard and weird to maintain when we use serialization. public abstract class AnimalBase { string Name { get; set; } // user-readable double Weight { get; set; } Habitat Habitat { get; set; } public void Swim(); { /* swim implementation; the same for all animals but depends uses the value of Weight */ } } public class Otter: AnimalBase{ public Otter() { Name = "Otter"; Weight = 10; Habitat = "North America"; } } // ... and so on Just plain awful. Static fields This blog post gave me and idea for a solution where each option is a statically defined field inside the type, like this: public class Animal { public static readonly Animal Otter = new Animal { Name="Otter", Weight = 10, Habitat = "North America"} // the rest of the animals... public string Name { get; set; } // user-readable public double Weight { get; set; } public Habitat Habitat { get; set; } public void Swim(); } That would be great: you can use it like enums (AnimalType = Animal.Otter), you can easily add a static list of all defined animals, you have a sensible place where to implement Swim(). Immutability can be achieved by making property setters protected. There is a major problem, though: it breaks serializability. A serialized Animal would have to save all its properties and upon deserialization it would create a new instance of Animal, which is something I'd like to avoid. Is there an easy way to make the third attempt work? Any more suggestions for implementing such a model?

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  • Use native HBitmap in C# while preserving alpha channel/transparency. Please check this code, it works on my computer...

    - by David
    Let's say I get a HBITMAP object/handle from a native Windows function. I can convert it to a managed bitmap using Bitmap.FromHbitmap(nativeHBitmap), but if the native image has transparency information (alpha channel), it is lost by this conversion. There are a few questions on Stack Overflow regarding this issue. Using information from the first answer of this question (How to draw ARGB bitmap using GDI+?), I wrote a piece of code that I've tried and it works. It basically gets the native HBitmap width, height and the pointer to the location of the pixel data using GetObject and the BITMAP structure, and then calls the managed Bitmap constructor: Bitmap managedBitmap = new Bitmap(bitmapStruct.bmWidth, bitmapStruct.bmHeight, bitmapStruct.bmWidth * 4, PixelFormat.Format32bppArgb, bitmapStruct.bmBits); As I understand (please correct me if I'm wrong), this does not copy the actual pixel data from the native HBitmap to the managed bitmap, it simply points the managed bitmap to the pixel data from the native HBitmap. And I don't draw the bitmap here on another Graphics (DC) or on another bitmap, to avoid unnecessary memory copying, especially for large bitmaps. I can simply assign this bitmap to a PictureBox control or the the Form BackgroundImage property. And it works, the bitmap is displayed correctly, using transparency. When I no longer use the bitmap, I make sure the BackgroundImage property is no longer pointing to the bitmap, and I dispose both the managed bitmap and the native HBitmap. The Question: Can you tell me if this reasoning and code seems correct. I hope I will not get some unexpected behaviors or errors. And I hope I'm freeing all the memory and objects correctly. private void Example() { IntPtr nativeHBitmap = IntPtr.Zero; /* Get the native HBitmap object from a Windows function here */ // Create the BITMAP structure and get info from our nativeHBitmap NativeMethods.BITMAP bitmapStruct = new NativeMethods.BITMAP(); NativeMethods.GetObjectBitmap(nativeHBitmap, Marshal.SizeOf(bitmapStruct), ref bitmapStruct); // Create the managed bitmap using the pointer to the pixel data of the native HBitmap Bitmap managedBitmap = new Bitmap( bitmapStruct.bmWidth, bitmapStruct.bmHeight, bitmapStruct.bmWidth * 4, PixelFormat.Format32bppArgb, bitmapStruct.bmBits); // Show the bitmap this.BackgroundImage = managedBitmap; /* Run the program, use the image */ MessageBox.Show("running..."); // When the image is no longer needed, dispose both the managed Bitmap object and the native HBitmap this.BackgroundImage = null; managedBitmap.Dispose(); NativeMethods.DeleteObject(nativeHBitmap); } internal static class NativeMethods { [StructLayout(LayoutKind.Sequential)] public struct BITMAP { public int bmType; public int bmWidth; public int bmHeight; public int bmWidthBytes; public ushort bmPlanes; public ushort bmBitsPixel; public IntPtr bmBits; } [DllImport("gdi32", CharSet = CharSet.Auto, EntryPoint = "GetObject")] public static extern int GetObjectBitmap(IntPtr hObject, int nCount, ref BITMAP lpObject); [DllImport("gdi32.dll")] internal static extern bool DeleteObject(IntPtr hObject); }

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  • How to use AVCaptureSession to stream live preview video, then take a photo, then return to streaming

    - by Matthew
    I have an application that creates its own live preview prior to taking a still photo. The app needs to run some processing on the image data and thus is not able to rely on AVCaptureVideoPreviewLayer. Getting the initial stream to work is going quite well, using Apple's example code. The problem comes when I try to switch to the higher quality image to take the snapshot. In response to a button press I attempt to reconfigure the session for taking a full resolution photo. I've tried many variations but here is my latest example (which still does not work): - (void)sessionSetupForPhoto { [session beginConfiguration]; session.sessionPreset = AVCaptureSessionPresetPhoto; AVCaptureStillImageOutput *output = [[[AVCaptureStillImageOutput alloc] init] autorelease]; for (AVCaptureOutput *output in [session outputs]) { [session removeOutput:output]; } if ([session canAddOutput:output]){ [session addOutput:output]; } else { NSLog(@"Not able to add an AVCaptureStillImageOutput"); } [session commitConfiguration]; } I am consistently getting an error message just after the commitConfiguration line that looks like this: (that is to say, I am getting an AVCaptureSessionRuntimeErrorNotification sent to my registered observer) Received an error: NSConcreteNotification 0x19d870 {name = AVCaptureSessionRuntimeErrorNotification; object = ; userInfo = { AVCaptureSessionErrorKey = "Error Domain=AVFoundationErrorDomain Code=-11800 \"The operation couldn\U2019t be completed. (AVFoundationErrorDomain error -11800.)\" UserInfo=0x19d810 {}"; The documentation in XCode ostensibly provides more information for the error number (-11800), "AVErrorUnknown - Reason for the error is unknown."; Previously I had also tried calls to stopRunning and startRunning, but no longer do that after watching WWDC Session 409, where it is discouraged. When I was stopping and starting, I was getting a different error message -11819, which corresponds to "AVErrorMediaServicesWereReset - The operation could not be completed because media services became unavailable.", which is much nicer than simply "unknown", but not necessarily any more helpful. It successfully adds the AVCaptureStillImageOutput (i.e., does NOT emit the log message). I am testing on an iPhone 3g (w/4.1) and iPhone 4. This call is happening in the main thread, which is also where my original AVCaptureSession setup took place. How can I avoid the error? How can I switch to the higher resolution to take the photo? Thank you!

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  • UIViewController not oreintating. Methods not called

    - by capple
    Greetings, This question does seem to be an ongoing saga in the world of iphone SDK... so heres my contribution... Had two separate projects from the same template... one semi-works, the other not at all... Please let me explain my steps... used this basic GL ES template //iphonedevelopment.blogspot.com/2008/12/opengl-project-template-for-xcode.html had to sort out some of the 'Release' configuration but otherwises has eveything I need to add orientation to a GL ES project. One my first project, did my stuff, then added these methods.... -(BOOL)shouldAutoRotateToInterfaceOrientation ..... -(void)willRotateToInterfaceOrientation .... -(void)didRotateFromInterfaceOrientation .... -(void)willAnimateRotationToInterfaceOrientation .... And understand what they do (or are trying to do in my case), the (BOOL)should... gets called once when the view controller is created, and returns 'YES'. But after that none of the other methods are called! So I started from scratch with a blank template (GL ES one from above)...and added minimum to support auto rotation. But this time none of the methods get called! So I investigated .... //developer.apple.com/iphone/library/qa/qa2010/qa1688.html as it said, I added the GLViewController.view first, then added the GLview as subviews of the application delegate. Nothing! Then found this //www.iphonedevsdk.com/forum/iphone-sdk-development/44993-how-determine-ipad-launch-orientation.html which states to enable orientation notifications [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications]; and then subsequently disable them in the view controller... makes sense...did it, nothing... I think the notifications might be on by default though, since I didn't need to enable them in the first project, yet it still try to verify a orientation (i.e (BOOL)shouldAutoRotate... )... If any one could help me out it would be greatly appreciated as this issue is driving me insane. Thanks in advance. The code can be found here ... http://rapidshare.com/files/392053688/autoRotation.zip N.B These projects avoid nib/xib resources, would like to keep it that way if possible. P.S iPad device not out where I am so I cannot test on a device yet. Would be nice for it to work on the simulator.

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  • How to bind Lists of a custom view model to a dropDownList an get the selected value after POST in A

    - by user187220
    I have following problem. In my view model I defined some list properties as follows: public class BasketAndOrderSearchCriteriaViewModel { List<KeyValuePair> currencies; public ICollection<KeyValuePair> Currencies { get { if (this.currencies == null) this.currencies = new List<KeyValuePair>(); return this.currencies; } } List<KeyValuePair> deliverMethods; public ICollection<KeyValuePair> DeliveryMethods { get { if (this.deliverMethods == null) this.deliverMethods = new List<KeyValuePair>(); return this.deliverMethods; } } } This view model is embedded in another view model: public class BasketAndOrderSearchViewModel { public BasketAndOrderSearchCriteriaViewModel Criteria { [System.Diagnostics.DebuggerStepThrough] get { return this.criteria; } } } I use 2 action methods; one is for the GET and the other for POST: [HttpGet] public ActionResult Search(BasketAndOrderSearchViewModel model){...} [HttpPost] public ActionResult SubmitSearch(BasketAndOrderSearchViewModel model){...} In the view I implement the whole view model by using the EditorFor-Html Helper which does not want to automatically display DropDownLists for List properties! 1. Question: How can you let EditorFor display DropDownLists? Since I could not figure out how to display DropDownLists by using EditorFor, I used the DropDownList Html helper and filled it through the view model as follows: public IEnumerable<SelectListItem> DeliveryMethodAsSelectListItem() { List<SelectListItem> list = new List<SelectListItem>(); list.Add(new SelectListItem() { Selected = true, Text = "<Choose Delivery method>", Value = "0" }); foreach (var item in this.DeliveryMethods) { list.Add(new SelectListItem() { Selected = false, Text = item.Value, Value = item.Key }); } return list; } My 2. question: As you can see I pass my view model to the action metho with POST attribute! Is there a way to get the selected value of a DropDownList get binded to the passed view model? At the moment all the DropDownList are empty and the selected value can only be fetched by the Request.Form which I definitely want to avoid! I would greatly appreciate some ideas or tips on this!

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  • General Questions on setting up Subversion (w/Netbeans) and web development workflow.

    - by Roeland
    Hey guys, I am web developer who currently works mostly on his own but, some projects require outside coding help (my brother.) Anyway, after running in to the problem of "working on the same files" and "saving over each others edits" I decided to research ways to avoid this. Through the help of stackoverflow I decided on subversion. My setup is the following: A windows 2008 server with a clean install. My desktop which is on the local network of the server. Then my brothers desktop which is at his house, not on lan. We both prefer to use netbeans for development. My Questions: How do we set this thing up correctly and most optimally. Here is my current setup and work flow. dev site: in the past I just created sub domains with my web host for test sites (company1.bythepixel.com, company2.bythepixel.com), and editted those sites with netbeans set up having remote sources (ftp). how do i set up my netbeans now? should I set it up with remote sources? I guess I may need to set up a web server on my local server. I'm just not sure of the work flow. When i hit save in netbeans.. will it update the repository.. then do i need to update the site from the repository somehow? live site: when going live, i would just copy all the files from the dev site into the live site. from what i gather i should be able to update the site from the dev repository? Currently I am toying with virtualsvn server (http://www.visualsvn.com/server/) on my local server. It looks like it is set up to use the http protocol. Is there advantages to this or should I consider something that does the file//. Do you recommend any other subversion software that would run on my 2008 box? how will my brother connect? should i set up a permanent vpn from his house to mine? suggestions? (not that important) how do I deal with databases, there anyway to do subversion on database? I know I have a lot of questions and I am trying to read / make sense of the free online subversion book, but its all so overwhelming! Wish there was a small subversion for dummies guide :)

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  • 1>main.obj : error LNK2001: unresolved external symbol _D3D10CreateDeviceAndSwapChain@32

    - by numerical25
    having trouble getting my directx going I get the following error 1>Linking... 1>main.obj : error LNK2001: unresolved external symbol _D3D10CreateDeviceAndSwapChain@32 1>C:\Users\numerical25\Desktop\Intro ToDirectX\msdnTutorials\tutorial0\tutorial\Debug\tutorial.exe : fatal error LNK1120: 1 unresolved externals below is my code // include the basic windows header file #include <windows.h> #include <windowsx.h> #include <d3d10.h> ID3D10Device* g_pd3dDevice; IDXGISwapChain* g_pSwapChain; // the WindowProc function prototype LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam); bool InitDirect3D(HWND); // the entry point for any Windows program int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) { // the handle for the window, filled by a function HWND hWnd; // this struct holds information for the window class WNDCLASSEX wc; // clear out the window class for use ZeroMemory(&wc, sizeof(WNDCLASSEX)); // fill in the struct with the needed information wc.cbSize = sizeof(WNDCLASSEX); wc.style = CS_HREDRAW | CS_VREDRAW; wc.lpfnWndProc = WindowProc; wc.hInstance = hInstance; wc.hCursor = LoadCursor(NULL, IDC_ARROW); wc.hbrBackground = (HBRUSH)COLOR_WINDOW; wc.lpszClassName = L"WindowClass1"; // register the window class RegisterClassEx(&wc); // create the window and use the result as the handle hWnd = CreateWindowEx(NULL, L"WindowClass1", // name of the window class L"Our First Windowed Program", // title of the window WS_OVERLAPPEDWINDOW, // window style 300, // x-position of the window 300, // y-position of the window 640, // width of the window 480, // height of the window NULL, // we have no parent window, NULL NULL, // we aren't using menus, NULL hInstance, // application handle NULL); // used with multiple windows, NULL // display the window on the screen ShowWindow(hWnd, nCmdShow); // enter the main loop: // this struct holds Windows event messages MSG msg; bool finished = InitDirect3D(hWnd); // Enter the infinite message loop while(TRUE) { // Check to see if any messages are waiting in the queue while(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) { // Translate the message and dispatch it to WindowProc() TranslateMessage(&msg); DispatchMessage(&msg); } // If the message is WM_QUIT, exit the while loop if(msg.message == WM_QUIT) break; // Run game code here // ... // ... }; } // this is the main message handler for the program LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) { // sort through and find what code to run for the message given switch(message) { // this message is read when the window is closed case WM_DESTROY: { // close the application entirely PostQuitMessage(0); return 0; } break; } // Handle any messages the switch statement didn't return DefWindowProc (hWnd, message, wParam, lParam); } bool InitDirect3D(HWND g_hWnd) { DXGI_SWAP_CHAIN_DESC sd; ZeroMemory( &sd, sizeof(sd) ); sd.BufferCount = 1; sd.BufferDesc.Width = 640; sd.BufferDesc.Height = 480; sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM; sd.BufferDesc.RefreshRate.Numerator = 60; sd.BufferDesc.RefreshRate.Denominator = 1; sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT; sd.OutputWindow = g_hWnd; sd.SampleDesc.Count = 1; sd.SampleDesc.Quality = 0; sd.Windowed = TRUE; if( FAILED( D3D10CreateDeviceAndSwapChain( NULL, D3D10_DRIVER_TYPE_REFERENCE, NULL, 0, D3D10_SDK_VERSION, &sd, &g_pSwapChain, &g_pd3dDevice ) ) ) { return FALSE; } return TRUE; }

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  • How to write this Linq SQL as a Dynamic Query (using strings)?

    - by Dr. Zim
    Skip to the "specific question" as needed. Some background: The scenario: I have a set of products with a "drill down" filter (Query Object) populated with DDLs. Each progressive DDL selection will further limit the product list as well as what options are left for the DDLs. For example, selecting a hammer out of tools limits the Product Sizes to only show hammer sizes. Current setup: I created a query object, sent it to a repository, and fed each option to a SQL "table valued function" where null values represent "get all products". I consider this a good effort, but far from DDD acceptable. I want to avoid any "programming" in SQL, hopefully doing everything with a repository. Comments on this topic would be appreciated. Specific question: How would I rewrite this query as a Dynamic Query? A link to something like 101 Linq Examples would be fantastic, but with a Dynamic Query scope. I really want to pass to this method the field in quotes "" for which I want a list of options and how many products have that option. from p in db.Products group p by p.ProductSize into g select new Category { PropertyType = g.Key, Count = g.Count() } Each DDL option will have "The selection (21)" where the (21) is the quantity of products that have that attribute. Upon selecting an option, all other remaining DDLs will update with the remaining options and counts. Edit: Additional notes: .OrderBy("it.City") // "it" refers to the entire record .GroupBy("City", "new(City)") // This produces a unique list of City .Select("it.Count()") //This gives a list of counts... getting closer .Select("key") // Selects a list of unique City .Select("new (key, count() as string)") // +1 to me LOL. key is a row of group .GroupBy("new (City, Manufacturer)", "City") // New = list of fields to group by .GroupBy("City", "new (Manufacturer, Size)") // Second parameter is a projection Product .Where("ProductType == @0", "Maps") .GroupBy("new(City)", "new ( null as string)")// Projection not available later? .Select("new (key.City, it.count() as string)")// GroupBy new makes key an object Product .Where("ProductType == @0", "Maps") .GroupBy("new(City)", "new ( null as string)")// Projection not available later? .Select("new (key.City, it as object)")// the it object is the result of GroupBy var a = Product .Where("ProductType == @0", "Maps") .GroupBy("@0", "it", "City") // This fails to group Product at all .Select("new ( Key, it as Product )"); // "it" is property cast though What I have learned so far is LinqPad is fantastic, but still looking for an answer. Eventually, completely random research like this will prevail I guess. LOL. Edit:

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  • SDL side-scroller scrolls inconsistantly

    - by SDLFunTimes
    So I'm working on an upgrade from my previous project (that I posted here for code review) this time implementing a repeating background (like what is used on cartoons) so that SDL doesn't have to load really big images for a level. There's a strange inconsistency in the program, however: the first time the user scrolls all the way to the right 2 less panels are shown than is specified. Going backwards (left) the correct number of panels is shown (that is the panels repeat the number of times specified in the code). After that it appears that going right again (once all the way at the left) the correct number of panels is shown and same going backwards. Here's some selected code and here's a .zip of all my code constructor: Game::Game(SDL_Event* event, SDL_Surface* scr, int level_w, int w, int h, int bpp) { this->event = event; this->bpp = bpp; level_width = level_w; screen = scr; w_width = w; w_height = h; //load images and set rects background = format_surface("background.jpg"); person = format_surface("person.png"); background_rect_left = background->clip_rect; background_rect_right = background->clip_rect; current_background_piece = 1; //we are displaying the first clip rect_in_view = &background_rect_right; other_rect = &background_rect_left; person_rect = person->clip_rect; background_rect_left.x = 0; background_rect_left.y = 0; background_rect_right.x = background->w; background_rect_right.y = 0; person_rect.y = background_rect_left.h - person_rect.h; person_rect.x = 0; } and here's the move method which is probably causing all the trouble: void Game::move(SDLKey direction) { if(direction == SDLK_RIGHT) { if(move_screen(direction)) { if(!background_reached_right()) { //move background right background_rect_left.x += movement_increment; background_rect_right.x += movement_increment; if(rect_in_view->x >= 0) { //move the other rect in to fill the empty space SDL_Rect* temp; other_rect->x = -w_width + rect_in_view->x; temp = rect_in_view; rect_in_view = other_rect; other_rect = temp; current_background_piece++; std::cout << current_background_piece << std::endl; } if(background_overshoots_right()) { //sees if this next blit is past the surface //this is used only for re-aligning the rects when //the end of the screen is reached background_rect_left.x = 0; background_rect_right.x = w_width; } } } else { //move the person instead person_rect.x += movement_increment; if(get_person_right_side() > w_width) { //person went too far right person_rect.x = w_width - person_rect.w; } } } else if(direction == SDLK_LEFT) { if(move_screen(direction)) { if(!background_reached_left()) { //moves background left background_rect_left.x -= movement_increment; background_rect_right.x -= movement_increment; if(rect_in_view->x <= -w_width) { //swap the rect in view SDL_Rect* temp; rect_in_view->x = w_width; temp = rect_in_view; rect_in_view = other_rect; other_rect = temp; current_background_piece--; std::cout << current_background_piece << std::endl; } if(background_overshoots_left()) { background_rect_left.x = 0; background_rect_right.x = w_width; } } } else { //move the person instead person_rect.x -= movement_increment; if(person_rect.x < 0) { //person went too far left person_rect.x = 0; } } } } without the rest of the code this doesn't make too much sense. Since there is too much of it I'll upload it here for testing. Anyway does anyone know how I could fix this inconsistency?

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  • C#: Inheritence, Overriding, and Hiding

    - by Rosarch
    I'm having difficulty with an architectural decision for my C# XNA game. The basic entity in the world, such as a tree, zombie, or the player, is represented as a GameObject. Each GameObject is composed of at least a GameObjectController, GameObjectModel, and GameObjectView. These three are enough for simple entities, like inanimate trees or rocks. However, as I try to keep the functionality as factored out as possible, the inheritance begins to feel unwieldy. Syntactically, I'm not even sure how best to accomplish my goals. Here is the GameObjectController: public class GameObjectController { protected GameObjectModel model; protected GameObjectView view; public GameObjectController(GameObjectManager gameObjectManager) { this.gameObjectManager = gameObjectManager; model = new GameObjectModel(this); view = new GameObjectView(this); } public GameObjectManager GameObjectManager { get { return gameObjectManager; } } public virtual GameObjectView View { get { return view; } } public virtual GameObjectModel Model { get { return model; } } public virtual void Update(long tick) { } } I want to specify that each subclass of GameObjectController will have accessible at least a GameObjectView and GameObjectModel. If subclasses are fine using those classes, but perhaps are overriding for a more sophisticated Update() method, I don't want them to have to duplicate the code to produce those dependencies. So, the GameObjectController constructor sets those objects up. However, some objects do want to override the model and view. This is where the trouble comes in. Some objects need to fight, so they are CombatantGameObjects: public class CombatantGameObject : GameObjectController { protected new readonly CombatantGameModel model; public new virtual CombatantGameModel Model { get { return model; } } protected readonly CombatEngine combatEngine; public CombatantGameObject(GameObjectManager gameObjectManager, CombatEngine combatEngine) : base(gameObjectManager) { model = new CombatantGameModel(this); this.combatEngine = combatEngine; } public override void Update(long tick) { if (model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); } base.Update(tick); } } Still pretty simple. Is my use of new to hide instance variables correct? Note that I'm assigning CombatantObjectController.model here, even though GameObjectController.Model was already set. And, combatants don't need any special view functionality, so they leave GameObjectController.View alone. Then I get down to the PlayerController, at which a bug is found. public class PlayerController : CombatantGameObject { private readonly IInputReader inputReader; private new readonly PlayerModel model; public new PlayerModel Model { get { return model; } } private float lastInventoryIndexAt; private float lastThrowAt; public PlayerController(GameObjectManager gameObjectManager, IInputReader inputReader, CombatEngine combatEngine) : base(gameObjectManager, combatEngine) { this.inputReader = inputReader; model = new PlayerModel(this); Model.Health = Constants.PLAYER_HEALTH; } public override void Update(long tick) { if (Model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); for (int i = 0; i < 10; i++) { Debug.WriteLine("YOU DEAD SON!!!"); } return; } UpdateFromInput(tick); // .... } } The first time that this line is executed, I get a null reference exception: model.Body.ApplyImpulse(movementImpulse, model.Position); model.Position looks at model.Body, which is null. This is a function that initializes GameObjects before they are deployed into the world: public void Initialize(GameObjectController controller, IDictionary<string, string> data, WorldState worldState) { controller.View.read(data); controller.View.createSpriteAnimations(data, _assets); controller.Model.read(data); SetUpPhysics(controller, worldState, controller.Model.BoundingCircleRadius, Single.Parse(data["x"]), Single.Parse(data["y"]), bool.Parse(data["isBullet"])); } Every object is passed as a GameObjectController. Does that mean that if the object is really a PlayerController, controller.Model will refer to the base's GameObjectModel and not the PlayerController's overriden PlayerObjectModel?

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  • Window Media Player issues two requests for the audio on web page

    - by Ron Harlev
    I'm using Windows Media Player in a web page. I have version 11 installed so that is the version I'm testing with right now. The player is embedded on the page with this HTML: <OBJECT id='MS_mediaPlayer' width="400" height="45" classid='CLSID:6BF52A52-394A-11D3-B153-00C04F79FAA6' codebase='http://activex.microsoft.com/activex/controls/mplayer/en/nsmp2inf.cab#Version=5,1,52,701' standby='Loading Microsoft Windows Media Player components...' type='application/x-oleobject'> <param name='autoStart' value="false"> <param name='uiMode' value="invisible"> <param name='loop' value="false"> </OBJECT> I'm calling in JavaScript: MS_mediaPlayer.URL = "SomeAudioFile.mp3" MS_mediaPlayer.controls.play(); When I look at Fiddler I can see that the player actually downloads "SomeAudioFile.mp3" twice. Is there some setting I have wrong? I was trying to set the "autoPlay" to true and avoid calling "play()". Got the same result - two downloads. UPDATE: The first request's user-agent is "Windows-Media-Player/11.0.5721.5268". The second has "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)". Looks like the browser is running the same request the second time. No Idea why Any ideas? UPDATE (4/1/10): Still no solution. I debugged the JS thoroughly and there is only one call to MediaPlayer.URL='.....' to set the audio file. Nothing else triggers the media player to load the file and there is no other place referencing the audio file on the page. One other interesting fact is that this doesn't happen (the double loading of the audio) when I run the browser locally on my development web server. But other remote requests to the same web server generate the double audio loading. I believe I eliminated any correlation with specific IE version or media player version. This happens with IE6-8 and WM9-12

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  • What is the best workaround for the WCF client `using` block issue?

    - by Eric King
    I like instantiating my WCF service clients within a using block as it's pretty much the standard way to use resources that implement IDisposable: using (var client = new SomeWCFServiceClient()) { //Do something with the client } But, as noted in this MSDN article, wrapping a WCF client in a using block could mask any errors that result in the client being left in a faulted state (like a timeout or communication problem). Long story short, when Dispose() is called, the client's Close() method fires, but throws and error because it's in a faulted state. The original exception is then masked by the second exception. Not good. The suggested workaround in the MSDN article is to completely avoid using a using block, and to instead instantiate your clients and use them something like this: try { ... client.Close(); } catch (CommunicationException e) { ... client.Abort(); } catch (TimeoutException e) { ... client.Abort(); } catch (Exception e) { ... client.Abort(); throw; } Compared to the using block, I think that's ugly. And a lot of code to write each time you need a client. Luckily, I found a few other workarounds, such as this one on IServiceOriented. You start with: public delegate void UseServiceDelegate<T>(T proxy); public static class Service<T> { public static ChannelFactory<T> _channelFactory = new ChannelFactory<T>(""); public static void Use(UseServiceDelegate<T> codeBlock) { IClientChannel proxy = (IClientChannel)_channelFactory.CreateChannel(); bool success = false; try { codeBlock((T)proxy); proxy.Close(); success = true; } finally { if (!success) { proxy.Abort(); } } } } Which then allows: Service<IOrderService>.Use(orderService => { orderService.PlaceOrder(request); } That's not bad, but I don't think it's as expressive and easily understandable as the using block. The workaround I'm currently trying to use I first read about on blog.davidbarret.net. Basically you override the client's Dispose() method wherever you use it. Something like: public partial class SomeWCFServiceClient : IDisposable { void IDisposable.Dispose() { if (this.State == CommunicationState.Faulted) { this.Abort(); } else { this.Close(); } } } This appears to be able to allow the using block again without the danger of masking a faulted state exception. So, are there any other gotchas I have to look out for using these workarounds? Has anybody come up with anything better?

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  • How do I call up values in PHP for user input in forms (radio buttons and selects)

    - by Derek
    Ok so my admin sets to edit a book which was created. I know how to bring in the values that were initially entered via a simple text field like 'bookname'. On the edit book page the book name field stores the currently assigned 'bookname' in the field (which is what I want! :) ) However I have other field types like selects and radio button entries...I'm having trouble calling in the already set value when the book was created. For example, there is a 'booklevel' field, which I have set as radio button entries as; Hard, Normal, and Easy. When the user goes to edit the book, I'm not too sure on how to have the current value drawn up (its stored as text) and the radio button being checked. I.e. 'Normal' is checked if this is what was set when the book was created. So far I have this as the code for the adding book level: <label>Book Level:</label> <label for="booklevel1" class="radio">Hard <input type="radio" name="booklevel" id="booklevel1" value="<?php echo 'Hard'; if (isset($_POST['booklevel'])); ?>"></label> <label for="booklevel2" class="radio">Medium<input type="radio" name="booklevel" id="booklevel2" value="<?php echo 'Normal'; if (isset($_POST['booklevel'])); ?>"></label> <label for="booklevel" class="radio">Low<input type="radio" name="booklevel" id="booklevel3" value="<?php echo 'Easy'; if (isset($_POST['booklevel'])); ?>"></label> This all works fine by the way when the user adds the book... But does anyone know how in my update book form, I can draw the value of what level has been set, and have the box checked?? To draw up the values in the text fields, I'm simply using: <?php echo $row['bookname']?> I also noticed a small issue when I call up the values for my Select options. I have the drop down select field display the currently set user (to read the book!), however, the drop down menu again displays the user in the list available options to select - basically meaning 2 of the same names appear in the list! Is there a way to eliminate the value of the SELECTED option? So far my setup for this is like: <select name="user_id" id="user_id"> <option value="<?php echo $row['user_id']?>" SELECTED><?php echo $row['fullname']?></option> <?php while($row = mysql_fetch_array($result)) { ?> <option value="<?php echo $row['user_id']?>"><?php echo $row['name']?></option> <?php } ?> </select> If anyone can help me I'll be very greatful. Sorry for the incredibly long question!! :)

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  • NSDocument Subclass not closed by NSWindowController?

    - by Nathan Douglas
    Okay, I'm fairly new to Cocoa and Objective-C, and to OOP in general. As background, I'm working on an extensible editor that stores the user's documents in a package. This of course required some "fun" to get around some issues with NSFileWrapper (i.e. a somewhat sneaky writing and loading process to avoid making NSFileWrappers for every single document within the bundle). The solution I arrived at was to essentially treat my NSDocument subclass as just a shell -- use it to make the folder for the bundle, and then pass off writing the actual content of the document to other methods. Unfortunately, at some point I seem to have completely screwed the pooch. I don't know how this happened, but closing the document window no longer releases the document. The document object doesn't seem to receive a "close" message -- or any related messages -- even though the window closes successfully. The end result is that if I start my app, create a new document, save it, then close it, and try to reopen it, the document window never appears. With some creative subclassing and NSLogging, I managed to figure out that the document object was still in memory, and still attached to the NSDocumentController instance, and so trying to open the document never got past the NSDocumentController's "hmm, currently have that one open" check. I did have an NSWindowController and NSDocumentController instance, but I've purged them from my project completely. I've overridden nearly every method for NSDocument trying to find out where the issue is. So far as I know, my Interface Builder bindings are all correct -- "Close" in the main menu is attached to "performClose:" of the First Responder, etc, and I've tried with fresh unsullied MainMenu and Document xibs as well. I thought that it might be something strange with my bundle writing code, so I basically deleted it all and started from scratch, but that didn't seem to work. I took out my init method overrides, and that didn't help either. I don't have the source of any simple document apps here, so I didn't try the next logical step (to substitute known-working code for mine in the readfromurl and writetourl methods). I've had this problem for about sixteen hours of uninterrupted troubleshooting now, and needless to say, I'm at the end of my rope. If I can't figure it out, I guess I'm going to try the project from scratch with a lot more code and intensity based around the bundle-document mess. Any help would be greatly appreciated.

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  • DataTable ReadXmlSchema and ReadXml Resulting in error

    - by MasterMax1313
    I'm having some trouble with the ReadXmlSchema and ReadXml methods for a DataTable. I'm getting the error "DataTable does not support schema inference from Xml". Code Snippet: I've tried Table.ReadXmlSchema(new StringReader(File.ReadAllText(XsdFilePath))); Table.ReadXml(new StringReader(File.ReadAllText(XmlFilePath))); And Table.ReadXmlSchema(XsdFilePath); Table.ReadXml(XmlFilePath); Xml Snippet: <ScreenSets> <ScreenSet id="Credit 1"> <Screen xmlFile="sb-credit1.en.xml" tabText="Recommendation" isCached="false"> <Buttons> <Button id="btnClosePresentation"/> </Buttons> </Screen> </ScreenSet> <ScreenSet id="Credit 2"> <Screen xmlFile="sb-credit2.en.xml" tabText="Recommendation" isCached="false"> <Buttons> <Button id="btnClosePresentation"/> </Buttons> </Screen> </ScreenSet> <ScreenSet id="Credit 3"> <Screen xmlFile="sb-credit3.en.xml" tabText="Recommendation" isCached="false"> <Buttons> <Button id="btnClosePresentation"/> </Buttons> </Screen> </ScreenSet> </ScreenSets> Xsd: <?xml version="1.0" encoding="utf-8"?> <xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="ScreenSets"> <xs:complexType> <xs:sequence> <xs:element maxOccurs="unbounded" name="ScreenSet"> <xs:complexType> <xs:sequence> <xs:element name="Screen"> <xs:complexType> <xs:sequence> <xs:element name="Buttons"> <xs:complexType> <xs:sequence> <xs:element maxOccurs="unbounded" name="Button"> <xs:complexType> <xs:attribute name="id" type="xs:string" use="required" /> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:sequence> <xs:attribute name="xmlFile" type="xs:string" use="required" /> <xs:attribute name="tabText" type="xs:string" use="required" /> <xs:attribute name="isCached" type="xs:boolean" use="required" /> </xs:complexType> </xs:element> </xs:sequence> <xs:attribute name="id" type="xs:string" use="required" /> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:schema>

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  • quartz: preventing concurrent instances of a job in jobs.xml

    - by Jason S
    This should be really easy. I'm using Quartz running under Apache Tomcat 6.0.18, and I have a jobs.xml file which sets up my scheduled job that runs every minute. What I would like to do, is if the job is still running when the next trigger time rolls around, I don't want to start a new job, so I can let the old instance complete. Is there a way to specify this in jobs.xml (prevent concurrent instances)? If not, is there a way I can share access to an in-memory singleton within my application's Job implementation (is this through the JobExecutionContext?) so I can handle the concurrency myself? (and detect if a previous instance is running) update: After floundering around in the docs, here's a couple of approaches I am considering, but either don't know how to get them to work, or there are problems. Use StatefulJob. This prevents concurrent access... but I'm not sure what other side-effects would occur if I use it, also I want to avoid the following situation: Suppose trigger times would be every minute, i.e. trigger#0 = at time 0, trigger #1 = 60000msec, #2 = 120000, #3 = 180000, etc. and the trigger#0 at time 0 fires my job which takes 130000msec. With a plain Job, this would execute triggers #1 and #2 while job trigger #0 is still running. With a StatefulJob, this would execute triggers #1 and #2 in order, immediately after #0 finishes at 130000. I don't want that, I want #1 and #2 not to run and the next trigger that runs a job should take place at #3 (180000msec). So I still have to do something else with StatefulJob to get it to work the way I want, so I don't see much of an advantage to using it. Use a TriggerListener to return true from vetoJobExecution(). Although implementing the interface seems straightforward, I have to figure out how to setup one instance of a TriggerListener declaratively. Can't find the docs for the xml file. Use a static shared thread-safe object (e.g. a semaphore or whatever) owned by my class that implements Job. I don't like the idea of using singletons via the static keyword under Tomcat/Quartz, not sure if there are side effects. Also I really don't want them to be true singletons, just something that is associated with a particular job definition. Implement my own Trigger which extends SimpleTrigger and contains shared state that could run its own TriggerListener. Again, I don't know how to setup the XML file to use this trigger rather than the standard <trigger><simple>...</simple></trigger>.

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