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  • When I type certain characters, they come out as backquotes

    - by JXG
    Very strange behavior. Some background: I bought a new lenovo G550 laptop, running Windows 7. I live in Israel. When I type certain keys, in any application, they are prefaced with the backquote (`). These characters are: Insert, Delete, Left Ctrl (the right-hand one is fine), - (the regular dash: the one on the keypad is fine), =, 5 (the regular one), 4 (the one on the numeric keypad, whether or not Num Lock is on), and PgDn (the regular one). When I press the Fn key with these I don't get the behavior. Does anyone know why this is happening, or how I can fix it?

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  • how to define a structural type that refers to itself?

    - by IttayD
    I want to create a method sum that I can call on different types, specifically sum(1,2). def sum[A](a1: A, a2: A) = a1 + a2 This fails because the compiler can't tell if A has a method '+' I tried to define a structural type: type Addable = {def +(a: Addable)} This fails because of an illegal cyclic reference How can I achieve this in a type safe way without requiring A to extend a specific trait?

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  • When Typing on my mac the cursor moves/deletes/replaces text.

    - by David
    Help! I don't know what is happening, with my computer (Macbook Black OSX 1ha0.6.6) but recently whenever I am typing my cursor suddenly moves in the middle of my frase or paragraph, deleting text, replacing words or just closing applications. I don't know what might be the cause but it's driving me crazy. I have disabled typinator (which had worked fine for a couple of months) and looked through the keybindings in SystemPreferencesKeyboardKeyboard Shortcuts. But for have not been able to find any answers. It happens in all apps that require typing. Textmate, Chrome, FIrefox, Texedit, Mail. Does anybody know if there is a way I can review all keyboard shortcuts, to see if the issue lies there or any suggestions? Thanking you dearly Dave

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  • why is the address bar black in Google chrome so you cannot see what you're typing ?

    - by Tim
    The address bar background color in Google Chrome is black. I cannot see what I'm typing. What's going on? This is a problem when you're typing in a URL you've never used before (so there's no matching history). Type in a URL you've never used before. Imagine someone is giving it to you over the phone. Make a typo somewhere. Use the back arrow to go back and correct it. You cannot see where the cursor is. This just started happening yesterday. I'm on WinXP Pro.

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  • How does a virtual machine work?

    - by Martin
    I've been looking into how programming languages work, and some of them have a so-called virtual machines. I understand that this is some form of emulation of the programming language within another programming language, and that it works like how a compiled language would be executed, with a stack. Did I get that right? With the proviso that I did, what bamboozles me is that many non-compiled languages allow variables with "liberal" type systems. In Python for example, I can write this: x = "Hello world!" x = 2**1000 Strings and big integers are completely unrelated and occupy different amounts of space in memory, so how can this code even be represented in a stack-based environment? What exactly happens here? Is x pointed to a new place on the stack and the old string data left unreferenced? Do these languages not use a stack? If not, how do they represent variables internally?

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  • Boo: Explicitly specifying the type of a hash

    - by Kiv
    I am new to Boo, and trying to figure out how to declare the type of a hash. When I do: myHash = {} myHash[key] = value (later) myHash[key].method() the compiler complains that "method is not a member of object". I gather that it doesn't know what type the value in the hash is. Is there any way I can declare to the compiler what type the keys and values of the hash are so that it won't complain?

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  • .NET template class instance - passing a variable data type

    - by FerretallicA
    As the title suggests, I'm tyring to pass a variable data type to a template class. Something like this: frmExample = New LookupForm(Of Models.MyClass) 'Works fine Dim SelectedType As Type = InstanceOfMyClass.GetType() 'Works fine frmExample = New LookupForm(Of SelectedType) 'Ba-bow! frmExample = New LookupForm(Of InstanceOfMyClass.GetType()) 'Ba-bow! LookupForm<Models.MyClass> frmExample; Type SelectedType = InstanceOfMyClass.GetType(); frmExample = new LookupForm<SelectedType.GetType()>(); //Ba-bow frmExample = new LookupForm<(Type)SelectedType>(); //Ba-bow I'm assuming it's something to do with the template being processed at compile time but even if I'm off the mark there, it wouldn't solve my problem anyway. I can't find any relevant information on using Reflection to instance template classes either. (How) can I create an instance of a dynamically typed repository at runtime?

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  • Should I use concrete Inheritance or not?

    - by Mez
    I have a project using Propel where I have three objects (potentially more in the future) Occasion Event extends Occasion Gig extends Occasion Occasion is an item that has the shared things, that will always be needed (Venue, start, end etc) With this - I want to be able to add in extra functionality, say for example, adding "Band" objects to the Gig object, or "Flyers" to an "Event" object. For this, I plan to create objects for these. However, without concrete inheritance, I have to have the foreign key point to the Occasion object - giving the (propel generated) functions for all of these extra bits to anything inherited from Occasion. I could, in theory do this without a foreign constraint, and add in functions to use the Peer or Query classes to get things related to the "Gig" or similar. Whereas with concrete inheritance, I would only have these functions in the things where they are. I think the decision here is whether I should Duck Type the objects (after all they are occasions) or whether I should just use the "Occasion" object as a "template" (only being used to search for things, like, all occasions at a venue) Thoughts? Comments?

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  • Enforce strong type checking in C (type strictness for typedefs)

    - by quinmars
    Is there a way to enforce explicit cast for typedefs of the same type? I've to deal with utf8 and sometimes I get confused with the indices for the character count and the byte count. So it be nice to have some typedefs: typedef unsigned int char_idx_t; typedef unsigned int byte_idx_t; With the addition that you need an explicit cast between them: char_idx_t a = 0; byte_idx_t b; b = a; // compile warning b = (byte_idx_t) a; // ok I know that such a feature doesn't exist in C, but maybe you know a trick or a compiler extension (preferable gcc) that does that. EDIT: I still don't really like the Hungarian notation in general, I couldn't used it for this problem because of project coding conventions, but I used it now in another similar case, where also the types are the same and the meanings are very similar. And I have to admit: it helps. I never would go and declare every integer with a starting "i", but as in Joel's example for overlapping types, it can be life saving.

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  • .NET generic class instance - passing a variable data type

    - by FerretallicA
    As the title suggests, I'm tyring to pass a variable data type to a template class. Something like this: frmExample = New LookupForm(Of Models.MyClass) 'Works fine Dim SelectedType As Type = InstanceOfMyClass.GetType() 'Works fine frmExample = New LookupForm(Of SelectedType) 'Ba-bow! frmExample = New LookupForm(Of InstanceOfMyClass.GetType()) 'Ba-bow! LookupForm<Models.MyClass> frmExample; Type SelectedType = InstanceOfMyClass.GetType(); frmExample = new LookupForm<SelectedType.GetType()>(); //Ba-bow frmExample = new LookupForm<(Type)SelectedType>(); //Ba-bow I'm assuming it's something to do with the template being processed at compile time but even if I'm off the mark there, it wouldn't solve my problem anyway. I can't find any relevant information on using Reflection to instance template classes either. (How) can I create an instance of a dynamically typed repository at runtime?

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  • var in C# - Why can't it be used as a member variable?

    - by David Neale
    Why is it not possible to have implicitly-typed variables at a class level within C# for when these variables are immediately assigned? ie: public class TheClass { private var aList = new List<string>(); } Is it just something that hasn't been implemented or is there a conceptual/technical reason for why it hasn't been done?

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  • Must a Language that Implements Monads be Statically Typed?

    - by Morgan Cheng
    I am learning functional programming style. From this link http://channel9.msdn.com/shows/Going+Deep/Brian-Beckman-Dont-fear-the-Monads/, Brian Beckman gave a brilliant introduction about Monad. He mentioned that Monad is about composition of functions so as to address complexity. A Monad includes a unit function that transfers type T to an amplified type M(T); and a Bind function that, given function from T to M(U), transforms type M(T) to another type M(U). (U can be T, but is not necessarily). In my understanding, the language implementing monad should be type-checked statically. Otherwise, type errors cannot be found during compilation and "Complexity" is not controlled. Is my understanding correct?

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  • Why would var be a bad thing?

    - by Spoike
    I've been chatting with my colleagues the other day and heard that their coding standard explicitly forbids them to use the var keyword in C#. They had no idea why it was so and I've always found implicit declaration to be incredibly useful when coding. I've never had any problems finding out what type the variable was (you only hover over the variable in VS and you'll get the type that way). Does anyone know why it would be a bad idea to use the var keyword in C#?

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  • VB.NET template instance - passing a variable data type

    - by FerretallicA
    As the title suggests, I'm tyring to pass a variable data type to a template class. Something like this: frmExample = New LookupForm(Of Models.MyClass) 'Works fine Dim SelectedType As Type = InstanceOfMyClass.GetType() 'Works fine repoGeneric = New Repositories.Repository(Of SelectedType) 'Ba-bow! repoGeneric = New Repositories.Repository(Of InstanceOfMyClass.GetType()) 'Ba-bow! I'm assuming it's something to do with the template being processed at compile time but even if I'm off the mark there, it wouldn't solve my problem anyway. I can't find any relevant information on using Reflection to instance template classes either. (How) can I create an instance of a dynamically typed repository at runtime?

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  • Why is C# statically typed?

    - by terrani
    I am a PHP web programmer who is trying to learn C#. I would like to know why C# requires me to specify the data type when creating a variable. Class classInstance = new Class(); Why do we need to know the data type before a class instance?

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  • Is the a pattern for iterating over lists held by a class (dynamicly typed OO languages)

    - by Roman A. Taycher
    If I have a class that holds one or several lists is it better to allow other classes to fetch those lists(with a getter) or to implement a doXList/eachXList type method for that list that take a function and call that function on each element of the list contained by that object. I wrote a program that did a ton of this and I hated passing around all these lists sometimes with method in class a calling method in class B to return lists contained in class C, B contains a C or multiple C's (note question is about dynamically typed OO languages languages like ruby or smalltalk) ex. (that came up in my program) on a Person class containing scheduling preferences and a scheduler class needing to access them.

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  • When would JavaScript == make more sense than ===?

    - by bryantsai
    As 359494 indicates they are basically identical except '===' also ensures type equality and hence '==' might perform type conversion. In Douglas Crockford's JavaScript: The Good Parts, it is advised to always avoid '=='. However, I'm wondering what the original thought of designing two set of equality operators was. Have you seen any situation that using '==' actually is more suitable than using '==='?

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  • Typed metaprogramming languages

    - by Jacques Carette
    I want to do some metaprogramming in a statically typed language, where both my programs and my meta-programs will be typed. I mean this in a strong sense: if my program generator compiles, I want the type system to be strong enough that only type-correct programs can be generated. As far as I know, only metaocaml can do this. (No, neither Template Haskell nor C++ templates fit the bill -- see this paper).

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  • C++: type Length from float

    - by anon
    This is kinda like my earlier question: http://stackoverflow.com/questions/2451175/c-vector3-type-wall Except, now, I want to do this to a builtin rather then a user created type. So I want a type "Length" that behaves just like float -- except I'm going to make it's constructor explicit, so I have to explicitly construct Length objects (rather than have random conversions flying around). Basically, I'm going into the type-a-lot camp.

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