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  • Flex list-controls - maintain remote data

    - by artemb
    Hello. I have a TileList which represents some remote data. I also have a form which allows me to change the data. And the data may be changed by someone else too. What is the best way to maintain data in the list in an up-to-date state? The simplest option I see is the following: Select an item in the list Edit it in the form Save it. The form submits the data to the server When the server reports success the list re-fetches it's data The very bad thing about this workflow is that the list loses selection (a tree would also loose the nodes' expanded/collapsed state). I would really love to find out another option which would enable the list to maintain it's selection state. Any guesses on how it may be done?

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  • (newbie) type signature "Maybe a" doesn't like "Just [Event]"

    - by sisif
    i'm still learning Haskell and need help with the type inference please! using packages SDL and Yampa i get the following type signature from FRP.Yampa.reactimate: (Bool -> IO (DTime, Maybe a)) and i want to use it for: myInput :: Bool -> IO (DTime, Maybe [SDL.Event]) myInput isBlocking = do event <- SDL.pollEvent return (1, Just [event]) ... reactimate myInit myInput myOutput mySF but it says Couldn't match expected type `()' against inferred type `[SDL.Event]' Expected type: IO (DTime, Maybe ()) Inferred type: IO (DTime, Maybe [SDL.Event]) In the second argument of `reactimate', namely `input' In the expression: reactimate initialize input output process i thought "Maybe a" allows me to use anything, even a SDL.Event list? why is it expecting "Maybe ()" when the type signature is actually "Maybe a"? why does it want an empty tuple, or a function taking no arguments, or what is () supposed to be?

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  • How to change a vairable type in C#?

    - by Mosho Mulan
    I wanted to use something like this: if(x==5) { var mydb= ........ ; } else { var mydb = ........ ; } but it didn't work because I can't declare a variable inside if statement. So I tried to do this: var mydb; if (x==5) { mydb= ............. ; } else { mydb=.............; } but id didn't work either because I had to initialize the variable (mydb). So the question is: I don't necessarily know the type of the variable, can I declare it anyway and then change the type inside the if statement?

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  • C# Type comparison

    - by Sean.C
    This has me pooped, is there any reason the following: public abstract class aExtension { public abstract bool LoadExtension(Constants c); // method required in inherit public abstract string AppliesToModule // property required in inherit { get; } public abstract string ExtensionName // property required in inherit { get; } public abstract string ExtensionDescription // property required in inherit { get; } } public class UK : aExtension { public override bool LoadExtension(Constants c) { return true; } public override string AppliesToModule { get { return "string"; } } public override string ExtensionName { get { return "string"; } } public override string ExtensionDescription { get { return "string"; } } } would return false for the following expressions: bool a = t.IsAssignableFrom(aExtension)); bool b = t.BaseType.IsAssignableFrom(aExtension)); bool c = typeof(aExtension).IsAssignableFrom(t); bool d = typeof(aExtension).IsAssignableFrom(t.BaseType); bool e = typeof(aExtension).IsSubclassOf(t); bool f = typeof(aExtension).IsSubclassOf(t.BaseType); bool g = t.IsSubclassOf(typeof(aExtension)); bool h = t.BaseType.IsSubclassOf(typeof(LBT.AdMeter.aExtension)); bool i = t.BaseType.Equals(typeof(aExtension)); bool j = typeof(aExtension).Equals(t.BaseType); T is the reflected Type from the calss UK. Stange thing is i do the exact same thing just on an external assembly in the same application and it works as expected...

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  • Strange type in c++

    - by Cemre
    I have a method with the prototype: bool getAssignment(const Query& query, Assignment *&result); I am a bit confused about the type of the second param (Assignment *&result) since I don't think I have seen something like that before. It is used like: Assignment *a; if (!getAssignment(query, a)) return false; Is it a reference to a pointer or the other way around ? or neither ? Any explanation is appreciated. Thanks.

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  • Haskell type signature with multiple type somethings (predicates?, for example Eq a =>)

    - by Andrew
    I'm not sure if type predicates is the right term, in fact I've never learned the word for this, so an edit to correct would be helpful - I'm referring to when you give the tipe of function f :: a -> b and you want to say a is a Eq and you say f :: Eq a => a -> b, the name for Eq a => - this is the thing i called a type predicate. My question, though, is how to have multiple of these, so if A is an Eq and B is a Num, I could say either f :: Eq a => a -> b or f :: Num b => a -> b. So, how can I have Eq a => and Num b => at the same time? f :: Eq a => Num b => a -> b, f :: Eq a -> Num b => a -> b, and f :: Eq a, Num b => a -> b all didn't do what I wanted.

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  • Save data from array in variable

    - by marcin_poland
    SOLVED! I`m trying save data from array in variable. I have in controller: $data = array('upload_data' => $this->upload->data()); and I know that in this array are data about uploading file. One with this date is "file_name", and I want to save this value in controller at variable. I try with: $image_name= $data['file_name']; But this not working. I use CodeIginter 2.1.3 framework. Good solution is: $data['upload_data']['file_name']; Thanks for help!

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  • Casting in mixed type calculations in C?

    - by yCalleecharan
    Hi, If I define these variables: double x0, xn, h; int n; and I have this mathematical expression: h = (xn - x0)/n; Is it necessary that I cast n into double prior doing the division for maximum accuracy like in h = (xn - x0)/ (double) n; I wrote a program to check the above but both expressions give the same answers. I understand that C will promote the integer to double type as variables xn and x0 are of type double but strangely enough in a book, the second expression with casting was emphasized. Thanks a lot...

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  • singledispatch in class, how to dispatch self type

    - by yanxinyou
    Using python3.4. Here I want use singledispatch to dispatch different type in __mul__ method . The code like this : class Vector(object): ## some code not paste @functools.singledispatch def __mul__(self, other): raise NotImplementedError("can't mul these type") @__mul__.register(int) @__mul__.register(object) # Becasue can't use Vector , I have to use object def _(self, other): result = Vector(len(self)) # start with vector of zeros for j in range(len(self)): result[j] = self[j]*other return result @__mul__.register(Vector) # how can I use the self't type @__mul__.register(object) # def _(self, other): pass # need impl As you can see the code , I want support Vector*Vertor , This has Name error Traceback (most recent call last): File "p_algorithms\vector.py", line 6, in <module> class Vector(object): File "p_algorithms\vector.py", line 84, in Vector @__mul__.register(Vector) # how can I use the self't type NameError: name 'Vector' is not defined The question may be How Can I use class Name a Type in the class's method ? I know c++ have font class statement . How python solve my problem ? And it is strange to see result = Vector(len(self)) where the Vector can be used in method body .

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  • C# property ending with ?

    - by MicMit
    What does that mean ? public bool? Verbose { get; set; } When applied to string? , there is an error Error 11 The type 'string' must be a non-nullable value type in order to use it as parameter 'T' in the generic type or method 'System.Nullable'

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  • Do I really need to return Type::size_type?

    - by dehmann
    I often have classes that are mostly just wrappers around some STL container, like this: class Foo { public: typedef std::vector<whatever> Vec; typedef Vec::size_type; const Vec& GetVec() { return vec_; } size_type size() { return vec_.size() } private: Vec vec_; }; I am not so sure about returning size_type. Often, some function will call size() and pass that value on to another function and that one will use it and maybe pass it on. Now everyone has to include that Foo header, although I'm really just passing some size value around, which should just be unsigned int anyway ...? What is the right thing to do here? Is it best practice to really use size_type everywhere?

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  • When should I define an hash code function for my types?

    - by devoured elysium
    Is there any other reason for implementing an hash code function for my types other than allowing for good use of hash tables? Let's say I am designing some types that I intend to use internally. I know that types are "internal" to the system, and I also know I will never use those types in hash tables. In spite of this, I decide I will have to redefine the equals() method. Theory says I should also redefine the hash code method, but I can't see any reason why, in this case, I should do it. Can anyone point me out any other reason? This question can be rephrased to : in which situations should we implement a hash code method in our types. PS : I am not asking how to implement one. I am asking when.

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  • Python: Matching & Stripping port number from socket data

    - by tobywuk
    Hello, I have data coming in to a python server via a socket. Within this data is the string '<port>80</port>' or which ever port is being used. I wish to extract the port number into a variable. The data coming in is not XML, I just used the tag approach to identifying data for future XML use if needed. I do not wish to use an XML python library, but simply use something like regexp and strings. What would you recommend is the best way to match and strip this data? I am currently using this code with no luck: p = re.compile('<port>\w</port>') m = p.search(data) print m Thank you :)

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  • Is it poor practice to identify objects via an enumeration property, instead of using GetType()?

    - by James
    I have a collection of objects that all implement one (custom) interface: IAuditEvent. Each object can be stored in a database and a unique numeric id is used for each object type. The method that stores the objects loops around a List<IAuditEvent>, so it needs to know the specific type of each object in order to store the correct numeric id. Is it poor practice to have an enumeration property on IAuditEvent so that each object can identify itself with a unique enumeration value? I can see that the simplest solution would be to write a method that translates a Type into an integer, but what if I need an enumeration of audit events for another purpose? Would it still be wrong to have my enumeration property on IAuditEvent?

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  • Best Practice for loading non-existent data

    - by Aizotu
    I'm trying to build a table in MS SQL 2008, loaded with roughly 50,000 rows of data. Right now I'm doing something like: Create Table MyCustomData ( ColumnKey Int Null, Column1 NVarChar(100) Null, Column2 NVarChar(100) Null Primary Key Clustered ( ColumnKey ASC ) WITH ( PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON ) ) CREATE INDEX IDX_COLUMN1 ON MyCustomData([COLUMN1]) CREATE INDEX IDX_COLUMN2 ON MyCustomData([COLUMN2]) DECLARE @MyCount Int SET @MyCount = 0 WHILE @MyCount < 50000 BEGIN INSERT INTO MyCustomData (ColumnKey, Column1, Column2) Select @MyCount + 1, 'Custom Data 1', 'Custom Data 2' Set @MyCount = @MyCount + 1 END My problem is that this is crazy slow. I thought at one point I could create a Select Statement to build my custom data and use that as the datasource for my Insert Into statement. i.e. something like INSERT INTO MyCustomData (ColumnKey, Column1, Column2) From (Select Top 50000 Row_Count(), 'Custom Data 1', 'Custom Data 2') I know this doesn't work, but its the only thing I can show that seems to provide an example of what I'm after. Any suggestions would be greatly appriciated.

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  • Finding the type of an object in C++

    - by lemnisca
    I have a class A and another class that inherits from it, B. I am overriding a function that accepts an object of type A as a parameter, so I have to accept an A. However, I later call functions that only B has, so I want to return false and not proceed if the object passed is not of type B. What is the best way to find out which type the object passed to my function is?

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  • Check if an object is order-able in python?

    - by sortfiend
    How can I check if an object is orderable/sortable in Python? I'm trying to implement basic type checking for the __init__ method of my binary tree class, and I want to be able to check if the value of the node is orderable, and throw an error if it isn't. It's similar to checking for hashability in the implementation of a hashtable. I'm trying to accomplish something similar to Haskell's (Ord a) => etc. qualifiers. Is there a similar check in Python?

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