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  • Python function argument scope (Dictionaries v. Strings)

    - by Shaun Meyer
    Hello, given: foo = "foo" def bar(foo): foo = "bar" bar(foo) print foo # foo is still "foo"... foo = {'foo':"foo"} def bar(foo): foo['foo'] = "bar" bar(foo) print foo['foo'] # foo['foo'] is now "bar"? I have a function that has been inadvertently over-writing my function parameters when I pass a dictionary. Is there a clean way to declare my parameters as constant or am I stuck making a copy of the dictionary within the function? Thanks!

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  • Race condition for thread startup

    - by Ozzah
    A similar question was asked here, but the answers generally all seem to relate to the lambda notation. I get a similar result without the lambda so I thought I'd ask for some clarification: Say I have something like this: for (int i = 0; i < 5; i++) (new Thread(new ThreadStart(delegate() { Console.WriteLine("Thread " + i); }))).Start(); One would expect the following output: Thread 0 Thread 1 Thread 2 Thread 3 Thread 4 Now I realise that the threads aren't started in any particular order, so let's just assume that the above lines can come out in any order. But that is not what happens. What instead happens: Thread 3 Thread 4 Thread 4 Thread 4 Thread 4 or something similar, which leads me to believe that rather than passing the value if i, it is passing the reference. (Which is weird, since an int is a value type). Doing something like this: for (int i = 0; i < 5; i++) (new Thread(new ThreadStart(delegate() { int j = i; Console.WriteLine("Thread " + j); }))).Start(); does not help either, even though we have made a copy of i. I am assuming the reason is that it hasn't made a copy of i in time. Doing something like this: for (int i = 0; i < 5; i++) { (new Thread(new ThreadStart(delegate() { Console.WriteLine("Thread " + i); }))).Start(); Thread.Sleep(50); } seems to fix the problem, however it is extremely undesirable as we're wasting 50ms on each iteration, not to mention the fact that if the computer is heavily loaded then maybe 50ms may not be enough. Here is a sample with my current, specific problem: Thread t = new Thread(new ThreadStart(delgate() { threadLogic(param1, param2, param3, param4); })); t.Start(); param1 = param2 = param3 = param4 = null; with: void threadLogic(object param1, object param2, object param3, object param4) { // Do some stuff here... } I want threadLogic() to run in its own thread, however the above code gives a null reference exception. I assume this is because the values are set to null before the thread has had a chance to start. Again, putting a Thread.Sleep(100) works, but it is an awful solution from every aspect. What do you guys recommend for this particular type of race condition?

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  • Passing dynamic parameters to a stored procedure in SQL Server 2008

    - by themhz
    I have this procedure that executes another procedure passed by a parameter and its parameters datefrom and dateto. CREATE procedure [dbo].[execute_proc] @procs varchar(200), @pdatefrom date, @pdateto date as exec @procs @datefrom=@pdatefrom,@dateto=@pdateto But I need to also pass the parameters dynamically without the need to edit them in the procedure. For example, what I am imagining is something like this CREATE procedure [dbo].[execute_proc] @procs varchar(200), @params varchar(max) as exec @procs @params where @params is a string like @param1=1,@param2='somethingelse' Is there a way to do this?

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  • g++ linker error--typeinfo, but not vtable

    - by James
    I know the standard answer for a linker error about missing typeinfo usually also involves vtable and some virtual function that I forgot to actually define. I'm fairly certain that's not the situation this time. Here's the error: UI.o: In function boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::Resource::GroupByState>(boost::shared_ptr<Graphics::Resource::GroupByState> const&, boost::detail::dynamic_cast_tag)': UI.cpp:(.text._ZN5boost10shared_ptrIN8Graphics7Widgets9WidgetSetEEC1INS1_8Resource12GroupByStateEEERKNS0_IT_EENS_6detail16dynamic_cast_tagE[boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::Resource::GroupByState>(boost::shared_ptr<Graphics::Resource::GroupByState> const&, boost::detail::dynamic_cast_tag)]+0x30): undefined reference totypeinfo for Graphics::Widgets::WidgetSet' Running c++filt on the obnoxious mangled name shows that it actually is looking at .boost::shared_ptr::shared_ptr(boost::shared_ptr const&, boost::detail::dynamic_cast_tag) The inheritance hierarchy looks something like class AbstractGroup { typedef boost::shared_ptr<AbstractGroup> Ptr; ... }; class WidgetSet : public AbstractGroup { typedef boost::shared_ptr<WidgetSet> Ptr; ... }; class GroupByState : public AbstractGroup { ... }; Then there's this: class UI : public GroupByState { ... void LoadWidgets( GroupByState::Ptr resource ); }; Then the original implementation: void UI::LoadWidgets( GroupByState::Ptr resource ) { WidgetSet::Ptr tmp( boost::dynamic_pointer_cast< WidgetSet >(resource) ); if( tmp ) { ... } } Stupid error on my part (trying to cast to a sibling class with a shared parent), even if the error is kind of cryptic. Changing to this: void UI::LoadWidgets( AbstractGroup::Ptr resource ) { WidgetSet::Ptr tmp( boost::dynamic_pointer_cast< WidgetSet >(resource) ); if( tmp ) { ... } } (which I'm fairly sure is what I actually meant to be doing) left me with a very similar error: UI.o: In function boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::_Drawer::Group>(boost::shared_ptr<Graphics::_Drawer::Group> const&, boost::detail::dynamic_cast_tag)': UI.cpp:(.text._ZN5boost10shared_ptrIN8Graphics7Widgets9WidgetSetEEC1INS1_7_Drawer5GroupEEERKNS0_IT_EENS_6detail16dynamic_cast_tagE[boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::_Drawer::Group>(boost::shared_ptr<Graphics::_Drawer::Group> const&, boost::detail::dynamic_cast_tag)]+0x30): undefined reference totypeinfo for Graphics::Widgets::WidgetSet' collect2: ld returned 1 exit status dynamic_cast_tag is just an empty struct in boost/shared_ptr.hpp. It's just a guess that boost might have anything at all to do with the error. Passing in a WidgetSet::Ptr totally eliminates the need for a cast, and it builds fine (which is why I think there's more going on than the standard answer for this question). Obviously, I'm trimming away a lot of details that might be important. My next step is to cut it down to the smallest example that fails to build, but I figured I'd try the lazy way out and take a stab on here first. TIA!

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  • C Objects in Objective-C

    - by paul simmons
    Hi, I couldn't find a clear explanation, just asking to be sure; are C data types handled same way (in terms of memory management) in Obj.C? i.e. they are created on stack, released immediately etc.? So they differ from Obj.C objects? Or may we make an analogy with C# (just an analogy not exactly) so that C types are handled as 'value types' and Obj.C objects as 'reference types'?

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  • How to animate the frame of an layer with CABasicAnimation?

    - by mystify
    I guess I have to convert the CGRect into an object to pass it to fromValue? This is how I try it, but it doesn't work: CABasicAnimation *frameAnimation = [CABasicAnimation animationWithKeyPath:@"frame"]; frameAnimation.duration = 2.5; frameAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; frameAnimation.fromValue = [NSValue valueWithCGRect:myLayer.frame]; frameAnimation.toValue = [NSValue valueWithCGRect:theNewFrameRect]; [myLayer addAnimation:frameAnimation forKey:@"MLC"];

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  • Meaning of message "operations coalesced during safepoint"

    - by elec
    A java app runs with the following flag: -XX:+PrintSafepointStatistics, and then produces the following line on the standard output console: 2 VM operations coalesced during safepoint Anyone cares to explain what this mean ? More generally - is there a Java reference manual somewhere detailling all JVM flags, their use and, most importantly, the expected output, with relevant explanations ?

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  • Why can't I access the instance.__class__ attribute in Python?

    - by froadie
    I'm new to Python, and I know I must be missing something pretty simple, but why doesn't this very, very simple code work? class myClass: pass testObject = myClass print testObject.__class__ I get the following error: AttributeError: class myClass has no attribute '__class__' Doesn't every object in Python have a __class__ attribute?

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  • Skin Twitter HTML and CSS

    - by hagope
    I am building a twitter application and would like to use the structure of the their homepage. Can anyone suggest how to go about doing this, or point to a reference that does this? I do not intend to use any images that would be considered copyright, I just want to use the single column layout, with the side panel, header, footer. Thanks!

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  • UITextField start at end of text

    - by Raphael Pinto
    I created an UITextField in my App. This text field display a long text. The problem is that when I first open the view containing the UITextField, it is automaticaly show the end of my text. But I want it to show the begining. I read the UITextFiled Class Reference on Apple dev center, but nothing seem to allow me to change it. How can I do?

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  • Why can't you call a non-static method from a static method?

    - by VoodooChild
    I have a static method [Method1] in my class, which calls another method [Method2] in the same class and is not a static method. But this is a no-no. I get this error: An object reference is required for the non-static field, method, or property "ClassName.MethodName()" Can someone please briefly describe why? including other things that might be related to this.

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  • How to create Insert script using c#

    - by karthik
    From my c# code behind, i pass a query to mysql database and get the data in a DataTable. Now i want to use the data in data table to write the Insert query in a script file [.sql] The objective of doing so is, whatever records i select from mysql, i should write that to a script file as backup. Thais why i need the insert statements. How ? Or any other idea is appreciated.

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  • IOC Container that can target .NET Framework Client Profile?

    - by Rox Wen
    On our current WPF project, we've been performing dependency injection using the Ninject IOC tool. We want to target the .NET Framework Client Profile for a better download/install experience. The problem is that Ninject seems to reference libararies such as System.Web which are NOT in the Client Profile. Can anyone recommend an IOC container that can target the .NET Framework Client Profile (3.5 or 4) ?

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  • Using Mathematica to generate crystal lattices

    - by lavabo
    How do you generate a 3x3x3 lattice in Mathematica? Is it possible to color some of the lattice points? It seems that it is possible but I cannot get it to work so far http://reference.wolfram.com/mathematica/ref/LatticeData.html What I mean by 3x3x3 is something like figure (c) on the right:http://physics.ucsd.edu/was-sdphul/labs/2dl/exp6/exp63.gif

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  • Marshalling non-Blittable Structs from C# to C++

    - by Greggo
    I'm in the process of rewriting an overengineered and unmaintainable chunk of my company's library code that interfaces between C# and C++. I've started looking into P/Invoke, but it seems like there's not much in the way of accessible help. We're passing a struct that contains various parameters and settings down to unmanaged codes, so we're defining identical structs. We don't need to change any of those parameters on the C++ side, but we do need to access them after the P/Invoked function has returned. My questions are: What is the best way to pass strings? Some are short (device id's which can be set by us), and some are file paths (which may contain Asian characters) Should I pass an IntPtr to the C# struct or should I just let the Marshaller take care of it by putting the struct type in the function signature? Should I be worried about any non-pointer datatypes like bools or enums (in other, related structs)? We have the treat warnings as errors flag set in C++ so we can't use the Microsoft extension for enums to force a datatype. Is P/Invoke actually the way to go? There was some Microsoft documentation about Implicit P/Invoke that said it was more type-safe and performant. For reference, here is one of the pairs of structs I've written so far: C++ /** Struct used for marshalling Scan parameters from managed to unmanaged code. */ struct ScanParameters { LPSTR deviceID; LPSTR spdClock; LPSTR spdStartTrigger; double spinRpm; double startRadius; double endRadius; double trackSpacing; UINT64 numTracks; UINT32 nominalSampleCount; double gainLimit; double sampleRate; double scanHeight; LPWSTR qmoPath; //includes filename LPWSTR qzpPath; //includes filename }; C# /// <summary> /// Struct used for marshalling scan parameters between managed and unmanaged code. /// </summary> [StructLayout(LayoutKind.Sequential)] public struct ScanParameters { [MarshalAs(UnmanagedType.LPStr)] public string deviceID; [MarshalAs(UnmanagedType.LPStr)] public string spdClock; [MarshalAs(UnmanagedType.LPStr)] public string spdStartTrigger; public Double spinRpm; public Double startRadius; public Double endRadius; public Double trackSpacing; public UInt64 numTracks; public UInt32 nominalSampleCount; public Double gainLimit; public Double sampleRate; public Double scanHeight; [MarshalAs(UnmanagedType.LPWStr)] public string qmoPath; [MarshalAs(UnmanagedType.LPWStr)] public string qzpPath; }

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  • empty sharepoint user profile property throw an exception

    - by James123
    I have a user profile property. user not assigned any value that property. If I use below code. It is thorwing exception " object reference not set to an instance of an object " userprof["OptOut"].ToString() I tried all types like if (userprof["OptOut"] != null) OR if(userprof["OptOut"].Value != null) nothing worked out for me. Here userProf object has value. userprof["OptOut"].Value is null How to handle this?

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  • How do you programmatically set a Style on a View?

    - by Greg
    I would like to do something like this: <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_cotent" style="@style/SubmitButtonType" /> But in code The xml approach works fine provided that SubmitButtonType is defined. Now what I assume happens is that the appt parser runs through this xml, generates an AttributeSet. That AttributeSet when passed to context/theme#obtainStyledAttributes() will have the style ref mask anything that is not written inline in this tag. Great that's fine! Now how do we do this programmatically. Button, as well as other View types, has a constructor that has the form: <Widget>(Context context, AttributeSet set, int defStyle). So I thought this would work. Button button = new Button(context, null, R.style.SubmitButtonType); However, I am finding that defStyle is badly documented as it really should be written to be a resourceId to an attribute (from R.attrs) that will be passed to obtainStyledAttributes() as the attribute resource, and not the style resource. After looking at the code, all the view implementations seem to pass 0 as the styleRef. I don't see the harm in having it passed as both the attr and the style resource (more flexible and negligible overhead) However I might be approaching this all wrong. How do you do this in code then other than by setting each individual element of the style to the specific widget you want to style (only possible by looking a the code to see what param maps to which method or set of methods). The only way I have found to do this is: <declare-styleable> <attr name="totallyAdhoc_attribute_just_for_this_case" format="reference"> </declare-styleable> <style name="MyAlreadyExistantTheme" > ... ... <item name="totallyAdhoc_attribute_just_for_this_case">@style/SubmitButtonType</item> </style> And instead of passing R.style.SubmitButtonType as defStyle, I pass the new R.attr.totallyAdhoc_attribute_just_for_this_case. Button button = new Button(context, null, R.attr.totallyAdhoc_attribute_just_for_this_case); This works but sounds way too complicated.

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  • Accessing custom user profile fields in CCK

    - by Nick Lowman
    I'm probably going about this the wrong way but... I’ve added a field to the User Profile called profile_real_name which is required by the user. Is there a way to access the details in CCK? For example in CCK when creating a new field I can access the user’s username with the ‘User reference’ Field type and setting the ‘Widget type’ to ‘Autocomplete text field’. Can I do the same with my real name field? Many thanks

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