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  • How to handle value types when embedding IronPython in C#?

    - by kloffy
    There is a well known issue when it comes to using .NET value types in IronPython. This has recently caused me a headache when trying to use Python as an embedded scripting language in C#. The problem can be summed up as follows: Given a C# struct such as: struct Vector { public float x; public float y; } And a C# class such as: class Object { public Vector position; } The following will happen in IronPython: obj = Object() print obj.position.x # prints ‘0’ obj.position.x = 1 print obj.position.x # still prints ‘0’ As the article states, this means that value types are mostly immutable. However, this is a problem as I was planning on using a vector library that is implemented as seen above. Are there any workarounds for working with existing libraries that rely on value types? Modifying the library would be the very last resort, but I'd rather avoid that.

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  • Which statically typed languages support intersection types for function return values?

    - by stakx
    Initial note: This question got closed after several edits because I lacked the proper terminology to state accurately what I was looking for. Sam Tobin-Hochstadt then posted a comment which made me recognise exactly what that was: programming languages that support intersection types for function return values. Now that the question has been re-opened, I've decided to improve it by rewriting it in a (hopefully) more precise manner. Therefore, some answers and comments below might no longer make sense because they refer to previous edits. (Please see the question's edit history in such cases.) Are there any popular statically & strongly typed programming languages (such as Haskell, generic Java, C#, F#, etc.) that support intersection types for function return values? If so, which, and how? (If I'm honest, I would really love to see someone demonstrate a way how to express intersection types in a mainstream language such as C# or Java.) I'll give a quick example of what intersection types might look like, using some pseudocode similar to C#: interface IX { … } interface IY { … } interface IB { … } class A : IX, IY { … } class B : IX, IY, IB { … } T fn() where T : IX, IY { return … ? new A() : new B(); } That is, the function fn returns an instance of some type T, of which the caller knows only that it implements interfaces IX and IY. (That is, unlike with generics, the caller doesn't get to choose the concrete type of T — the function does. From this I would suppose that T is in fact not a universal type, but an existential type.) P.S.: I'm aware that one could simply define a interface IXY : IX, IY and change the return type of fn to IXY. However, that is not really the same thing, because often you cannot bolt on an additional interface IXY to a previously defined type A which only implements IX and IY separately. Footnote: Some resources about intersection types: Wikipedia article for "Type system" has a subsection about intersection types. Report by Benjamin C. Pierce (1991), "Programming With Intersection Types, Union Types, and Polymorphism" David P. Cunningham (2005), "Intersection types in practice", which contains a case study about the Forsythe language, which is mentioned in the Wikipedia article. A Stack Overflow question, "Union types and intersection types" which got several good answers, among them this one which gives a pseudocode example of intersection types similar to mine above.

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  • Best Practices for Content Types in SharePoint

    - by Anna Karin
    Hi all, Recently, we came across a severe problem in production farm with the Content Types. I would like to explain the background of this problem first. We have nice working feature for Content Types installation in production and test farms. We developed and deployed (using wsps) this SharePoint feature in Visual studio. We are using the publishing pages using page layouts and Content Types to help content editors to quickly publish the web pages. Unfortunately, some Content Types have been manually updated/added by some people in the production, so whenever I (developer) make some changes to the existing Content Types (using Visual Studio and feature activation/deactivation) , SharePoint removes one or two columns (during feature activation/deactivation) from Content Types; or the columns which have not been added in a best practice way. I think the best practice is to update Content Types using Visual Studio. Now, I wish to ensure that site columns shouldn't get removed from Content Types upon feature activation/deactivation. Note: Our feature for Content Type activation/deactivation doesn't hold any activation dependencies in the feature.xml

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  • generating a class dynamically from types that are fetched at runtime

    - by Ritwik G
    is doing the following possible in C# (or in any other language) 1. I am fetching data from a database. At run time i can compute the no. of columns and data types of the columns fetched. 2. Next i want to "generate" a class with these data types as fields. I also want to store all the records that i fetch in a collection. The problem is that i wanna do both step **1** and **2** at runt ime is this possible ? I am using C# currently but i can shift to something else if i need to.

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  • How to acquire the Context in an Adobe AIR Native Extension?

    - by rotaercz
    In the following line of code... ProgressDialog progressDialog = ProgressDialog.show(getBaseContext(), "LOADING_TITLE", "LOADING_MESSAGE"); In place of getBaseContext() I've tried... getApplicationContext() this NativeActivity.this (NativeActivity)getApplicationContext() Among others. I'm not sure why it's not working. In the NativeExtensionContext which extends FREContext I am passing the activity using getActivity() to NativeActivity. Everything works well but I get a "Nullpointerexception" or “android.view.WindowManager$BadTokenException: Unable to add window — token null is not for an application” when I try I try to get a reference to the Context. Anyone with experience using Adobe AIR Native Extensions and/or Android Java would be great.

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  • Using CompareTo() on different .NET types (e.g. int vs. double)

    - by Yossin
    Hi, I've got a static method that accepts two object type variables and runs the CompareTo() method: public static int Compare(Object objA, Object objB) { return (((IComparable)objA).CompareTo(objB)); } Problem is that CompareTo() throws an exception when trying to compare between different types (e.g. int and double). Does any one know of a better way in C#, to compare between two different types? Or a workaround to this problem? Thanks

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  • Guessing Excel Data Types

    - by AjarnMark
    Note to Self HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\4.0\Engines\Excel: TypeGuessRows = 0 means scan everything. Note to Others About 10 years ago I stumbled across this bit of information just when I needed it and it saved my project.  Then for some reason, a few years later when it would have been nice, but not critical, for some reason I could not find it again anywhere.  Well, now I have stumbled across it again, and to preserve my future self from nightmares and sudden baldness due to pulling my hair out, I have decided to blog it in the hopes that I can find it again this way. Here’s the story…  When you query data from an Excel spreadsheet, such as with old-fashioned DTS packages in SQL 2000 (my first reference) or simply with an OLEDB Data Adapter from ASP.NET (recent task) and if you are using the Microsoft Jet 4.0 driver (newer ones may deal with this differently) then you can get funny results where the query reports back that a cell value is null even when you know it contains data. What happens is that Excel doesn’t really have data types.  While you can format information in cells to appear like certain data types (e.g. Date, Time, Decimal, Text, etc.) that is not really defining the cell as being of a certain type like we think of when working with databases.  But, presumably, to make things more convenient for the user (programmer) when you issue a query against Excel, the query processor tries to guess what type of data is contained in each column and returns it in an appropriate manner.  This is all well and good IF your data is consistent in every row and matches what the processor guessed.  And, for efficiency’s sake, when the query processor is trying to figure out each column’s data type, it does so by analyzing only the first 8 rows of data (default setting). Now here’s the problem, suppose that your spreadsheet contains information about clothing, and one of the columns is Size.  Now suppose that in the first 8 rows, all of your sizes look like 32, 34, 18, 10, and so on, using numbers, but then, somewhere after the 8th row, you have some rows with sizes like S, M, L, XL.  What happens is that by examining only the first 8 rows, the query processor inferred that the column contained numerical data, and then when it hits the non-numerical data in later rows, it comes back blank.  Major bummer, and a real pain to track down if you don’t know that Excel is doing this, because you study the spreadsheet and say, “the data is RIGHT THERE!  WHY doesn’t the query see it?!?!”  And the hair-pulling begins. So, what’s a developer to do?  One option is to go to the registry setting noted above and change the DWORD value of TypeGuessRows from the default of 8 to 0 (zero).  Setting this value to zero will force Jet to scan every row in the spreadsheet before making its determination as to what type of data the column contains.  And that means that in the example above, it would have treated the column as a string rather than as numeric, and presto! your query now returns all of the values that you know are in there. Of course, there is a caveat… if you are querying large spreadsheets, making Jet scan every row can be quite a performance hit.  You could enter a different number (more than 8) that you believe is a better sampling of rows to make the guess, but you still have the possibility that every row scanned looks alike, but that later rows are different, and that you might get blanks when there really is data there.  That’s the type of gamble, I really don’t like to take with my data. Anyone with a better approach, or with experience with more recent drivers that have a better way of handling data types, please chime in!

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  • Types of semantic bugs, logic errors [closed]

    - by C-Otto
    I am a PhD student and currently focus on automatically finding instances of new types of bugs in (Java) programs that cannot be found by existing tools like FindBugs. The existing tool currently is used to prove/disprove termination of (Java) programs. I have some ideas (see below), but I could need more input from you (experienced programmers, potential users of my tool). What kind of bugs do you wish to find? What types of bugs exist and might be suitable for my analysis? One strength of the approach I use is detailled information about the heap. So in contrast to FindBugs, I can work with knowledge of the form "variable x and variable y are disjoint on the heap" or "variable z is not cyclic". It is also possible to see if a method might have side effects (and if so, which variables may/may not be affected by it). Example 1: Vacuous call: Graph graphOne = createGraph(); Graph graphTwo = createGraph(); Node source = graphTwo.getRootNode(); for (Node n : graphOne.getNodes()) { if (areConnected(source, n)) { graphTwo.addNode(n); } } Imagine createGraph() creates a fresh graph, so that graphOne and graphTwo are disjoint on the heap. Then, because source is taken from graphTwo instead of graphOne, the call to areConnected always returns false. In this situation I could find out that the call areConnected is useless (because it does not have any side effect and the return value always is false) which helps finding the real bug (taking source from the wrong graph). For this the information that x and y are disjoint (because graphOne and graphTwo are disjoint) is crucial. This bug is related to calling x.equals(y) where x and y are objects of different classes. In this scenario, most implementations of equals() always return false, which most likely is not the intended result. FindBugs already finds this bug (hardcoded to equals(), semantics of implementation is not checked). Example 2: Useless code: someCode(); while (something()) { yetMoreSomething(); } moreCode(); In the case that the loop (so the code in something() and yetMoreSomething()) does not modify anything visible outside the loop, it does not make sense to run this code - the program has the same behaviour as someCode(); moreCode() (i.e., without the loop). To find this out, one needs detailled information about the side effects of the (possibly useless) code. If I can prove that the code does not have any side effect that can be observed afterwards (in the example: in moreCode() or later), then the code indeed is useless. Of course, here Input/Output of any form must be seen as a side effect, so that a System.out.println(...) is not considered useless. Example 3: Ignored return value: Instead of x = foo(); and making use of x, the method is called without storing the result: foo();. If the method does not have any side effect, its invocation is useless and can be dropped. Most likely, the bug here is that the returned value should have been used. Here, too, detailled information about side effects are needed. Can you think of similar types of bugs that might be detected (only) with detailled information about the heap, side effects, semantics of called methods, ...? Did you encounter bugs related to the ones shown below in "real life"? By the way, the tool is AProVE and Java related publications can be found on my homepage. Thanks a lot, Carsten

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  • NHibernate Pitfalls: Custom Types and Detecting Changes

    - by Ricardo Peres
    This is part of a series of posts about NHibernate Pitfalls. See the entire collection here. NHibernate supports the declaration of properties of user-defined types, that is, not entities, collections or primitive types. These are used for mapping a database columns, of any type, into a different type, which may not even be an entity; think, for example, of a custom user type that converts a BLOB column into an Image. User types must implement interface NHibernate.UserTypes.IUserType. This interface specifies an Equals method that is used for comparing two instances of the user type. If this method returns false, the entity is marked as dirty, and, when the session is flushed, will trigger an UPDATE. So, in your custom user type, you must implement this carefully so that it is not mistakenly considered changed. For example, you can cache the original column value inside of it, and compare it with the one in the other instance. Let’s see an example implementation of a custom user type that converts a Byte[] from a BLOB column into an Image: 1: [Serializable] 2: public sealed class ImageUserType : IUserType 3: { 4: private Byte[] data = null; 5: 6: public ImageUserType() 7: { 8: this.ImageFormat = ImageFormat.Png; 9: } 10: 11: public ImageFormat ImageFormat 12: { 13: get; 14: set; 15: } 16: 17: public Boolean IsMutable 18: { 19: get 20: { 21: return (true); 22: } 23: } 24: 25: public Object Assemble(Object cached, Object owner) 26: { 27: return (cached); 28: } 29: 30: public Object DeepCopy(Object value) 31: { 32: return (value); 33: } 34: 35: public Object Disassemble(Object value) 36: { 37: return (value); 38: } 39: 40: public new Boolean Equals(Object x, Object y) 41: { 42: return (Object.Equals(x, y)); 43: } 44: 45: public Int32 GetHashCode(Object x) 46: { 47: return ((x != null) ? x.GetHashCode() : 0); 48: } 49: 50: public override Int32 GetHashCode() 51: { 52: return ((this.data != null) ? this.data.GetHashCode() : 0); 53: } 54: 55: public override Boolean Equals(Object obj) 56: { 57: ImageUserType other = obj as ImageUserType; 58: 59: if (other == null) 60: { 61: return (false); 62: } 63: 64: if (Object.ReferenceEquals(this, other) == true) 65: { 66: return (true); 67: } 68: 69: return (this.data.SequenceEqual(other.data)); 70: } 71: 72: public Object NullSafeGet(IDataReader rs, String[] names, Object owner) 73: { 74: Int32 index = rs.GetOrdinal(names[0]); 75: Byte[] data = rs.GetValue(index) as Byte[]; 76: 77: this.data = data as Byte[]; 78: 79: if (data == null) 80: { 81: return (null); 82: } 83: 84: using (MemoryStream stream = new MemoryStream(this.data ?? new Byte[0])) 85: { 86: return (Image.FromStream(stream)); 87: } 88: } 89: 90: public void NullSafeSet(IDbCommand cmd, Object value, Int32 index) 91: { 92: if (value != null) 93: { 94: Image data = value as Image; 95: 96: using (MemoryStream stream = new MemoryStream()) 97: { 98: data.Save(stream, this.ImageFormat); 99: value = stream.ToArray(); 100: } 101: } 102: 103: (cmd.Parameters[index] as DbParameter).Value = value ?? DBNull.Value; 104: } 105: 106: public Object Replace(Object original, Object target, Object owner) 107: { 108: return (original); 109: } 110: 111: public Type ReturnedType 112: { 113: get 114: { 115: return (typeof(Image)); 116: } 117: } 118: 119: public SqlType[] SqlTypes 120: { 121: get 122: { 123: return (new SqlType[] { new SqlType(DbType.Binary) }); 124: } 125: } 126: } In this case, we need to cache the original Byte[] data because it’s not easy to compare two Image instances, unless, of course, they are the same.

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  • How should I name a native DLL distributed in both 32-bit and 64-bit form?

    - by Spike0xff
    I have a commercial product that's a DLL (native 32-bit code), and now it's time to build a 64-bit version of it. So when installing on 64-bit Windows, the 32-bit version goes into Windows\SysWOW64, and the 64-bit version goes into... Windows\System32! (I'm biting my tongue here...) Or the DLL(s) can be installed alongside the client application. What should I name the 64-bit DLL? Same name as 32-bit: Two files that do the same thing, have the same name, but are totally non-interchangeable. Isn't that a recipe for confusion and support problems? Different names (e.g. product.dll and product64.dll): Now client applications have to know whether they are running 32-bit or 64-bit in order to reference my DLL, and there are languages where that isn't known until run-time - .NET being just one example. And now all the statically compiled clients have to conditionalize the import declarations: IF target=WIN64 THEN import Blah from "product64.dll" ELSE import Blah from "product.dll" ENDIF The product contains massive amounts of C code, and a large chunk of C++ - porting it to C# is not an option. Advice? Suggestions?

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  • Why Does DreamWeaver CS5 Discriminate between File Extensions, Even After Modding Mime Types!?

    - by Sam
    Hi folks, Even After I forced DreamWeaver CS5 to allow opening of .ast extensions as a MIME type of php5, which DreamWeaver now opens and colors correctly as described here, I still have trouble figuring out why it still discriminates between the two file extensions! Symptoms: External Files & Design View I have a file foo.php which php includes other files (e.g. the php-combined css.php and js.php). Now, when opening foo.php all functions work perfectly: the external (included) php files are all recognised correctly. However, when I change foo.php foo.ast, and open it again, It does not recognise the files extensions anymore in the top bar. Also, I lose the Design / Live View functionality.** When I change foo.ast to foo.php, all works again! Anyone any clues of why there remains a a difference between one and other extension? Note1: I have added the .ast extension to these four files, next to .php: 1 C:\Users\Sam\AppData\Local\VirtualStore\Program Files (x86)\Adobe\Adobe Dreamweaver CS5\configuration\DocumentTypes\MMDocumentTypes.xml 2 C:\Program Files (x86)\Adobe\Adobe Dreamweaver CS5\configuration\DocumentTypes\MMDocumentTypes.xml 3 C:\Users\Sam\AppData\Roaming\Adobe\Dreamweaver CS5\en_US\Configuration\Extensions.txt 4 C:\Program Files (x86)\Adobe\Adobe Dreamweaver CS5\configuration\Extensions.txt Note2: sometimes, even .php files do not want to show in design view or live view. Could this be caused by a corrupted installation?

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  • General Overview of Design Pattern Types

    Typically most software engineering design patterns fall into one of three categories in regards to types. Three types of software design patterns include: Creational Type Patterns Structural Type Patterns Behavioral Type Patterns The Creational Pattern type is geared toward defining the preferred methods for creating new instances of objects. An example of this type is the Singleton Pattern. The Singleton Pattern can be used if an application only needs one instance of a class. In addition, this singular instance also needs to be accessible across an application. The benefit of the Singleton Pattern is that you control both instantiation and access using this pattern. The Structural Pattern type is a way to describe the hierarchy of objects and classes so that they can be consolidated into a larger structure. An example of this type is the Façade Pattern.  The Façade Pattern is used to define a base interface so that all other interfaces inherit from the parent interface. This can be used to simplify a number of similar object interactions into one single standard interface. The Behavioral Pattern Type deals with communication between objects. An example of this type is the State Design Pattern. The State Design Pattern enables objects to alter functionality and processing based on the internal state of the object at a given time.

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  • Entity system and rendering types

    - by Papi75
    I would like to implement entity system in my game and I've got some question about entity system and rendering. Currently, my renderer got two types of elements: Current design Mesh : A default renderable with a Material, a Geometry and a Transformable Sprite : A type of mesh with some methods like "flip" and "setRect" methods and a rect member (With an imposed geometry, a quad) This objects inherit from "Spacial" class. Questions: How can I handle this two types in an entity system? I'm thinking about using "MeshComponent" and "SpriteComponent", but if I do that, an entity could have a Mesh and a Sprite at the same type, it's look stupid, right? I thought the idea to have a parent "rendering" component : "RenderableComponent" for "MeshComponent" and "SpriteComponent" but it will be difficult to handle "cast" in the game (ex: did I need to ask entity-getComponent or SpineComponent, …) Thanks a lot for reading me! My entity system work like that: --------------------------------------------------------------------------- Entity* entity = world->createEntity(); MeshComponent* mesh = entity->addComponent<MeshComponent>(material); mesh->loadFromFile("monkey.obj"); PhysicComponent* physic = entity->addComponent<PhysicComponent>(); physic->setMass(5.4f); physic->setVelocity( 0.5f, 2.f ); --------------------------------------------------------------------------- class RenderingSystem { private: Scene scene; public: void onEntityAdded( Entity* entity ) { scene.addMesh( entity->getComponent<MeshComponent>() ); } } class PhysicSystem { private: World world; public: void onEntityAdded( Entity* entity ) { world.addBody( entity->getComponent<PhysicComponent>()->getBody() ); } void process( Entity* entity ) { PhysicComponent* physic = entity->getComponent<PhysicComponent>(); } } ---------------------------------------------------------------------------

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  • Create a custom shortcut that types clipboard contents

    - by briankb
    I want to paste my clipboard contents to a remote session such as VNC, IPMI, or Raritan. To accomplish this, I installed xdotool and clip. Then I wrote a simple command that types the clipboard contents: xdotool type "$(xclip -o)" This works if I stay in a terminal window, and type that command myself. It types back my clipboard contents when I run the command. Of course now I want to make this into a hotkey that works in any window. However, if I create a custom shortcut using Keyboard settings, it doesn't work. If I assign a hotkey Alt+K to the shortcut, nothing happens when I press it. If I use Ctrl+K, unexpected behavior occurs to whatever window has focus. e.g. my terminal window size shrinks (it's somewhat amusing, actually). Similar results occur if I save it as a script and call the script, or if I encapsulate the command with sh -c. How can I make practical use of the powerful xdotool type command?

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  • DD-WRT with native IPv6

    - by Matt
    My ISP provides native IPv6 support (ie. I can plug in my computer straight into the WAN and get an IPv6 address). However I can not get this working on DD-WRT. When I enable IPv6 and radvd in DD-WRT, the router gets in IPv6 address, but the devices on my LAN do not. I tried looking at the DD-WRT wiki, but this only displayed instructions for tunneling or other methods where native support isn't available. I found a small amount of sites thorough searching, but none of the methods these sites described gave my computers each a global IPv6 address. In addition, SSHing into the router using ping6 on sites such as ipv6.google.com causes "host unreachable" errors. Has anyone using DD-WRT configured a successful setup with native IPv6? I am using a Netgear WNDR3700 v2, with DD-WRT build 17201

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  • sqlcmd won't execute - Claims Native Client not installed properly

    - by nuit9
    I'm trying to use sqlcmd to execute some SQL scripts. Using a test command with a simple query like: sqlcmd -S HOSTNAME -d MYDATABASE -Q 'SELECT Names FROM Customers' sqlcmd does not appear to make any attempt to connect to the server as it displays this message: Sqlcmd: Error: Connection failure. SQL Native Client is not installed correctly. To correct this, run SQL Server Setup. The native client was presumably installed as part of the SQL Server setup and likely correctly. I actually get this message on any machine with SQL server installed trying to use sqlcmd so it's not a matter of the installation being corrupt. Unfortunately the message really tells me nothing about the problem so I don't know what the real issue is. I know the SQL Native client is working properly since a vbscript was able to execute SQL queries against the database. Is there some additional configuration needed to use sqlcmd?

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