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  • Converting string to a simple type

    - by zespri
    .Net framework contains a great class named Convert that allows conversion between simple types, DateTime type and String type. Also the class support conversion of the types implementing IConvertible interface. The class has been implemented in the very first version of .Net framework. There were a few things in the first .Net framework that were not done quite right. For example .Parse methods on simple types would throw an exception if the string couldn't be parsed and there would be no way to check if exception is going to be thrown in advance. A future version of .Net Framework removed this deficiency by introducing the TryParse method that resolved this problem. The Convert class dates back to time of the old Parse method, so the ChangeType method on this class in implemented old style - if conversion can't be performed an exception is thrown. Take a look at the following code: public static T ConvertString<T>(string s, T @default) { try { return (T)Convert.ChangeType(s, typeof(T), CultureInfo.InvariantCulture); } catch (Exception) { return @default; } } This code basically does what I want. However I would pretty much like to avoid the ugly try/catch here. I'm sure, that similar to TryParse, there is a modern method of rewriting this code without the catch-all. Could you suggest one?

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  • PowerShell - Parameter Value Tab Expansion for Enum types

    - by Adam Driscoll
    Is it possible to implement parameter value tab expansion for enum parameter types? Creating a binary cmdlet with parameter definition: [Parameter] public SomeEnum Type {get;set;} Is there some way to type: Add-MyThing -Type S<tab> To get: Add-MyThing -Type SomeEnumValue Where: public enum SomeEnum { SomeEnumValue, SomeEnumValue2 } I know it may be possible with overriding the TabExpansion function but I was wondering if there was something I could do within my cmdlet to expose this type of functionality.

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  • allow file download to all types of files

    - by Avinash
    hi i have given my user to upload nay types of files. But my problem is that how can i force user top just download any type of files? Since pdf, jpg and text files are directly viewable to browser. So i want that any type of file should be downloaded to view. Running on php Thanks Avinash

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  • How does SimpleWorkerRequest associate MIME types with extensions?

    - by Justin Dearing
    I was serving html referencing svg files in Cassini, and having problems since the mime type was not being sent properly. I ended up writing my own port of Cassini that set the extension based on mime type. After a good night of sleep I realized that there might be some sort of registry key or config file where I can configure custom mime types for SimpleWorkerRequest, the .NET class that serves content through Casinni. However, I don't know what that is.

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  • Haskell newbie on types

    - by garulfo
    I'm completely new to Haskell (and more generally to functional programming), so forgive me if this is really basic stuff. To get more than a taste, I try to implement in Haskell some algorithmic stuff I'm working on. I have a simple module Interval that implements intervals on the line. It contains the type data Interval t = Interval t t the helper function makeInterval :: (Ord t) => t -> t -> Interval t makeInterval l r | l <= r = Interval l r | otherwise = error "bad interval" and some utility functions about intervals. Here, my interest lies in multidimensional intervals (d-intervals), those objects that are composed of d intervals. I want to separately consider d-intervals that are the union of d disjoint intervals on the line (multiple interval) from those that are the union of d interval on d separate lines (track interval). With distinct algorithmic treatments in mind, I think it would be nice to have two distinct types (even if both are lists of intervals here) such as import qualified Interval as I -- Multilple interval newtype MInterval t = MInterval [I.Interval t] -- Track interval newtype TInterval t = TInterval [I.Interval t] to allow for distinct sanity checks, e.g. makeMInterval :: (Ord t) => [I.Interval t] -> MInterval t makeMInterval is = if foldr (&&) True [I.precedes i i' | (i, i') <- zip is (tail is)] then (MInterval is) else error "bad multiple interval" makeTInterval :: (Ord t) => [I.Interval t] -> TInterval t makeTInterval = TInterval I now get to the point, at last! But some functions are naturally concerned with both multiple intervals and track intervals. For example, a function order would return the number of intervals in a multiple interval or a track interval. What can I do? Adding -- Dimensional interval data DInterval t = MIntervalStuff (MInterval t) | TIntervalStuff (TInterval t) does not help much, since, if I understand well (correct me if I'm wrong), I would have to write order :: DInterval t -> Int order (MIntervalStuff (MInterval is)) = length is order (TIntervalStuff (TInterval is)) = length is and call order as order (MIntervalStuff is) or order (TIntervalStuff is) when is is a MInterval or a TInterval. Not that great, it looks odd. Neither I want to duplicate the function (I have many functions that are concerned with both multiple and track intevals, and some other d-interval definitions such as equal length multiple and track intervals). I'm left with the feeling that I'm completely wrong and have missed some important point about types in Haskell (and/or can't forget enough here about OO programming). So, quite a newbie question, what would be the best way in Haskell to deal with such a situation? Do I have to forget about introducing MInterval and TInterval and go with one type only? Thanks a lot for your help, Garulfo

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  • Asp.Net Dynamic Data + Complex Types

    - by Feryt
    Hi. Is there any way how to work with complex types in asp.net dynamic data web site? If we have Entity(ie from EF) "Person" with complex type "Address", "Table.GetScaffoldColumns()" does not returns comlumns for property of type "Address". Thank you.

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  • Blittable Value Types

    - by Michael Covelli
    Here is a list of blittable types. It contains Int32 and Int64. But I don't see just plain "int" on the list. How does C# treat the plain "int" type? Does it just get replaced with Int32 or Int64 depending on the system? Or is there a subtle difference? Will using "int" ever cause a performance hit for marshalling?

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  • Different Types of Linked Lists!

    - by Jay
    What are the different types of Linked Lists which are commonly used? I know and have used the following: Singly Linked List Doubly Linked List Circular List What are the other kinds of lists that have been used by you or known to you?

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  • Casting Between Data Types in C#

    - by Jimbo
    I have (for example) an object of type A that I want to be able to cast to type B (similar to how you can cast an int to a float) Data types A and B are my own. Is it possible to define the rules by which this casting occurs? Example int a = 1; float b = (float)a; int c = (int)b;

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  • HTML Types - Learning Order?

    - by Gabe
    I've decided that today - as soon as this question is answered, in fact - I'm going to dive into learning HTML. But, looking online, I've noticed there are many types: HTML, XHTML, HTML5, and so on. So, which should I start with? In what order should I learn them? And, for that first language, where should I learn at?

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  • Possible form field types per model field type

    - by Jonathan
    Django's documentation specifies for each model field type the corresponding default form field type. Alas, I couldn't find in the documentation, or anywhere else, what form field types are possible per model field type. Not all combinations are possible, right? Same question for widgets...

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  • How to modify PropertyGrid at runtime (add/remove property and dynamic types/enums)

    - by salle55
    How do you modify a propertygrid at runtime in every way? I want to be able to add and remove properties and add "dynamic types", what I mean with that is a type that result in a runtime generated dropdown in the propertygrid using a TypeConverter. I have actually been able to do both those things (add/remove properties and add dynamic type) but only separately not at the same time. To implement the support to add and remove properties at runtime I used this codeproject article and modified the code a bit to support different types (not just strings). private System.Windows.Forms.PropertyGrid propertyGrid1; private CustomClass myProperties = new CustomClass(); public Form1() { InitializeComponent(); myProperties.Add(new CustomProperty("Name", "Sven", typeof(string), false, true)); myProperties.Add(new CustomProperty("MyBool", "True", typeof(bool), false, true)); myProperties.Add(new CustomProperty("CaptionPosition", "Top", typeof(CaptionPosition), false, true)); myProperties.Add(new CustomProperty("Custom", "", typeof(StatesList), false, true)); //<-- doesn't work } /// <summary> /// CustomClass (Which is binding to property grid) /// </summary> public class CustomClass: CollectionBase,ICustomTypeDescriptor { /// <summary> /// Add CustomProperty to Collectionbase List /// </summary> /// <param name="Value"></param> public void Add(CustomProperty Value) { base.List.Add(Value); } /// <summary> /// Remove item from List /// </summary> /// <param name="Name"></param> public void Remove(string Name) { foreach(CustomProperty prop in base.List) { if(prop.Name == Name) { base.List.Remove(prop); return; } } } etc... public enum CaptionPosition { Top, Left } My complete solution can be downloaded here. It works fine when I add strings, bools or enums, but when I try to add a "dynamic type" like StatesList it doesn't work. Does anyone know why and can help me to solve it? public class StatesList : System.ComponentModel.StringConverter { private string[] _States = { "Alabama", "Alaska", "Arizona", "Arkansas" }; public override System.ComponentModel.TypeConverter.StandardValuesCollection GetStandardValues(ITypeDescriptorContext context) { return new StandardValuesCollection(_States); } public override bool GetStandardValuesSupported(ITypeDescriptorContext context) { return true; } public override bool GetStandardValuesExclusive(ITypeDescriptorContext context) { return true; } } The method of using a TypeConverter works fine when you don't try to add the property at runtime, for example this code works without any problem, but I want to be able to do both. Please take a look at my project. Thanks!

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  • EXTRACT for TIMESTAMP types in SQLite3

    - by umuthorax
    Hi, It seems extract function is not supported by SQLite3 for timestamp types (ref). For example; select extract(year from l_shipdate) as l_year from ... gives the following error; Error: near "from": syntax error I wonder whether there is an alternative way to do this in SQLite3 (or through rewriting the SQL query). Thanks in advance,

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  • Contravariant Delegates Value Types

    - by ChloeRadshaw
    Can anyone shed light on why contravariance does not work with C# value types? The below does not work private delegate Asset AssetDelegate(int m); internal string DoMe() { AssetDelegate aw = new AssetDelegate(DelegateMethod); aw(32); return "Class1"; } private static House DelegateMethod(object m) { return null; }

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  • Can one create Sized Types in Scala?

    - by Jens Schauder
    Is it possible to create types like e.g. String(20) in scala? The aim would be to have compiler checks for things like: a: String(20) b: String(30) a = b; // throws a compiler exception when no implicit conversion is available b= a; // works just fine Note: It doesn't need to be/named String

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