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  • "Subclassing" show in Haskell?

    - by me2
    Lets say I have the following: data Greek = Alpha | Beta | Gamma | Phi deriving Show I want to use the default showing of all items except Beta, which I want to say "two". Can I do this?

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  • Custom BindAttribute

    - by Chao
    Is there a way to implement your own BindAttribute. Preferably by deriving from BindAttribute, but if you need to impliment it in your own ModelBinder how would you go about doing this?

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  • Creating Haskell instance declarations

    - by btl
    Hello, complete noob to Haskell here with probably an even noobier question. I'm trying to get ghci output working and am stuck on instance declarations. How could I declare an instance for "(Show (Stack - Stack))" given: data Cmd = LD Int | ADD | MULT | DUP deriving Show type Prog = [Cmd] type Stack = [Int] type D = Stack -> Stack I've been trying to create a declaration like: instance Show D where show = Stack but all my attempts have resulted in illegal instance declarations. Any help and/or references much appreciated!

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  • Loop Control within a DataflowTask in ETL

    - by Ben
    Hi, Being fairly new to SSIS and the ETL process, I was wondering if there is anyway to loop though a record set within a DataFlowTask and pass each row (deriving parameters from the row) into a Stored Procedure (the next step in the ETL phase). Once i have passed the row into the stored procedure, I want the results from each iteration to be written to a Table. Does anyone know how to do this? Thanks.

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  • How do you unit test a class that's meant to talk to data?

    - by Arda Xi
    I have a few repository classes that are meant to talk to different kinds of data, deriving from an IRepository interface laid out like so: In implementations, the code talks to a data source, be this a directory of XML files or a database or even just a cache. Is it possible to reliably unit test any of these implementations? I don't see a mock implementation working, because then I'm only testing the mock code and not the actual code.

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  • Does Hibernate always need a setter when there is a getter?

    - by Marcus
    We have some Hibernate getter methods annotated with both @Column and @Basic. We get an exception if we don't have the corresponding setter. Why is this? In our case we are deriving the value returned from the getter (to get stored in the DB) and the setter has no functional purpose. So we just have an empty method to get around the error condition..

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  • functional dependencies vs type families

    - by mhwombat
    I'm developing a framework for running experiments with artificial life, and I'm trying to use type families instead of functional dependencies. Type families seems to be the preferred approach among Haskellers, but I've run into a situation where functional dependencies seem like a better fit. Am I missing a trick? Here's the design using type families. (This code compiles OK.) {-# LANGUAGE TypeFamilies, FlexibleContexts #-} import Control.Monad.State (StateT) class Agent a where agentId :: a -> String liveALittle :: Universe u => a -> StateT u IO a -- plus other functions class Universe u where type MyAgent u :: * withAgent :: (MyAgent u -> StateT u IO (MyAgent u)) -> String -> StateT u IO () -- plus other functions data SimpleUniverse = SimpleUniverse { mainDir :: FilePath -- plus other fields } defaultWithAgent :: (MyAgent u -> StateT u IO (MyAgent u)) -> String -> StateT u IO () defaultWithAgent = undefined -- stub -- plus default implementations for other functions -- -- In order to use my framework, the user will need to create a typeclass -- that implements the Agent class... -- data Bug = Bug String deriving (Show, Eq) instance Agent Bug where agentId (Bug s) = s liveALittle bug = return bug -- stub -- -- .. and they'll also need to make SimpleUniverse an instance of Universe -- for their agent type. -- instance Universe SimpleUniverse where type MyAgent SimpleUniverse = Bug withAgent = defaultWithAgent -- boilerplate -- plus similar boilerplate for other functions Is there a way to avoid forcing my users to write those last two lines of boilerplate? Compare with the version using fundeps, below, which seems to make things simpler for my users. (The use of UndecideableInstances may be a red flag.) (This code also compiles OK.) {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, UndecidableInstances #-} import Control.Monad.State (StateT) class Agent a where agentId :: a -> String liveALittle :: Universe u a => a -> StateT u IO a -- plus other functions class Universe u a | u -> a where withAgent :: Agent a => (a -> StateT u IO a) -> String -> StateT u IO () -- plus other functions data SimpleUniverse = SimpleUniverse { mainDir :: FilePath -- plus other fields } instance Universe SimpleUniverse a where withAgent = undefined -- stub -- plus implementations for other functions -- -- In order to use my framework, the user will need to create a typeclass -- that implements the Agent class... -- data Bug = Bug String deriving (Show, Eq) instance Agent Bug where agentId (Bug s) = s liveALittle bug = return bug -- stub -- -- And now my users only have to write stuff like... -- u :: SimpleUniverse u = SimpleUniverse "mydir"

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  • Creating a Haskell Empty Set

    - by mvid
    I am attempting to pass back a Node type from this function, but I get the error that empty is out of scope: import Data.Set (Set) import qualified Data.Set as Set data Node = Vertex String (Set Node) deriving Show toNode :: String -> Node toNode x = Vertex x empty What am I doing wrong?

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  • Why won't the following haskell code compile?

    - by voxcogitatio
    I'm in the process of writing a small lisp interpreter in haskell. In the process i defined this datatype, to get a less typed number; data Number = _Int Integer | _Rational Rational | _Float Double deriving(Eq,Show) Compiling this fails with the following error: ERROR "types.hs":16 - Syntax error in data type declaration (unexpected `|') Line 16 is the line w. the first '|' in the code above.

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  • What does Protected Internal means in .Net

    - by vaibhav
    Protected Means, we can access this member only in a deriving class, and internal means we can access this member in any type in the same assembly using a object. So can I consider a Protected Internal member as a public member in the same assembly. and as a protected member in the different assembly.

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  • Implementing a very simple 'Wine Rating System' in Haskell

    - by Alex N
    Hello, I have just started learning Haskell and have got stumped on how to add a rating to a custom data type. The data type I'm using has a name, a year and a tuple (userName and their rating), it looks like: data Wine = Wine String Int [Rating] deriving (Eq,Ord,Show,Read) type Rating = (String, Int) I wanted to allow a user to rate a given wine from a database, stored as [Wine] but cant figure out how to to it. Any pointers or suggestions would be greatly appreciated! Thanks.

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  • Are comonads a good fit for modeling the Wumpus world?

    - by Tim Stewart
    I'm trying to find some practical applications of a comonad and I thought I'd try to see if I could represent the classical Wumpus world as a comonad. I'd like to use this code to allow the Wumpus to move left and right through the world and clean up dirty tiles and avoid pits. It seems that the only comonad function that's useful is extract (to get the current tile) and that moving around and cleaning tiles would not use be able to make use of extend or duplicate. I'm not sure comonads are a good fit but I've seen a talk (Dominic Orchard: A Notation for Comonads) where comonads were used to model a cursor in a two-dimensional matrix. If a comonad is a good way of representing the Wumpus world, could you please show where my code is wrong? If it's wrong, could you please suggest a simple application of comonads? module Wumpus where -- Incomplete model of a world inhabited by a Wumpus who likes a nice -- tidy world but does not like falling in pits. import Control.Comonad -- The Wumpus world is made up of tiles that can be in one of three -- states. data Tile = Clean | Dirty | Pit deriving (Show, Eq) -- The Wumpus world is a one dimensional array partitioned into three -- values: the tiles to the left of the Wumpus, the tile occupied by -- the Wumpus, and the tiles to the right of the Wumpus. data World a = World [a] a [a] deriving (Show, Eq) -- Applies a function to every tile in the world instance Functor World where fmap f (World as b cs) = World (fmap f as) (f b) (fmap f cs) -- The Wumpus world is a Comonad instance Comonad World where -- get the part of the world the Wumpus currently occupies extract (World _ b _) = b -- not sure what this means in the Wumpus world. This type checks -- but does not make sense to me. extend f w@(World as b cs) = World (map world as) (f w) (map world cs) where world v = f (World [] v []) -- returns a world in which the Wumpus has either 1) moved one tile to -- the left or 2) stayed in the same place if the Wumpus could not move -- to the left. moveLeft :: World a -> World a moveLeft w@(World [] _ _) = w moveLeft (World as b cs) = World (init as) (last as) (b:cs) -- returns a world in which the Wumpus has either 1) moved one tile to -- the right or 2) stayed in the same place if the Wumpus could not move -- to the right. moveRight :: World a -> World a moveRight w@(World _ _ []) = w moveRight (World as b cs) = World (as ++ [b]) (head cs) (tail cs) initWorld = World [Dirty, Clean, Dirty] Dirty [Clean, Dirty, Pit] -- cleans the current tile cleanTile :: Tile -> Tile cleanTile Dirty = Clean cleanTile t = t Thanks!

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  • How does one use TrafficStats.incrementOperationCount()?

    - by Dheeraj
    The documentation for TrafficStats.incrementOperationCount() says: Increment count of network operations performed under the given accounting tag. This can be used to derive bytes-per-operation. I want to find the total number of bytes transferred during a particular network operation. Since this API claims to help in deriving bytes-per-operation, can someone help me understand how to use it?

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  • BI Applications overview

    - by sv744
    Welcome to Oracle BI applications blog! This blog will talk about various features, general roadmap, description of functionality and implementation steps related to Oracle BI applications. In the first post we start with an overview of the BI apps and will delve deeper into some of the topics below in the upcoming weeks and months. If there are other topics you would like us to talk about, pl feel free to provide feedback on that. The Oracle BI applications are a set of pre-built applications that enable pervasive BI by providing role-based insight for each functional area, including sales, service, marketing, contact center, finance, supplier/supply chain, HR/workforce, and executive management. For example, Sales Analytics includes role-based applications for sales executives, sales management, as well as front-line sales reps, each of whom have different needs. The applications integrate and transform data from a range of enterprise sources—including Siebel, Oracle, PeopleSoft, SAP, and others—into actionable intelligence for each business function and user role. This blog  starts with the key benefits and characteristics of Oracle BI applications. In a series of subsequent blogs, each of these points will be explained in detail. Why BI apps? Demonstrate the value of BI to a business user, show reports / dashboards / model that can answer their business questions as part of the sales cycle. Demonstrate technical feasibility of BI project and significantly lower risk and improve success Build Vs Buy benefit Don’t have to start with a blank sheet of paper. Help consolidate disparate systems Data integration in M&A situations Insulate BI consumers from changes in the OLTP Present OLTP data and highlight issues of poor data / missing data – and improve data quality and accuracy Prebuilt Integrations BI apps support prebuilt integrations against leading ERP sources: Fusion Applications, E- Business Suite, Peoplesoft, JD Edwards, Siebel, SAP Co-developed with inputs from functional experts in BI and Applications teams. Out of the box dimensional model to source model mappings Multi source and Multi Instance support Rich Data Model    BI apps have a very rich dimensionsal data model built over 10 years that incorporates best practises from BI modeling perspective as well as reflect the source system complexities  Thanks for reading a long post, and be on the lookout for future posts.  We will look forward to your valuable feedback on these topics as well as suggestions on what other topics would you like us to cover. I Conformed dimensional model across all business subject areas allows cross functional reporting, e.g. customer / supplier 360 Over 360 fact tables across 7 product areas CRM – 145, SCM – 47, Financials – 28, Procurement – 20, HCM – 27, Projects – 18, Campus Solutions – 21, PLM - 56 Supported by 300 physical dimensions Support for extensive calendars; Gregorian, enterprise and ledger based Conformed data model and metrics for real time vs warehouse based reporting  Multi-tenant enabled Extensive BI related transformations BI apps ETL and data integration support various transformations required for dimensional models and reporting requirements. All these have been distilled into common patterns and abstracted logic which can be readily reused across different modules Slowly Changing Dimension support Hierarchy flattening support Row / Column Hybrid Hierarchy Flattening As Is vs. As Was hierarchy support Currency Conversion :-  Support for 3 corporate, CRM, ledger and transaction currencies UOM conversion Internationalization / Localization Dynamic Data translations Code standardization (Domains) Historical Snapshots Cycle and process lifecycle computations Balance Facts Equalization of GL accounting chartfields/segments Standardized values for categorizing GL accounts Reconciliation between GL and subledgers to track accounted/transferred/posted transactions to GL Materialization of data only available through costly and complex APIs e.g. Fusion Payroll, EBS / Fusion Accruals Complex event Interpretation of source data – E.g. o    What constitutes a transfer o    Deriving supervisors via position hierarchy o    Deriving primary assignment in PSFT o    Categorizing and transposition to measures of Payroll Balances to specific metrics to support side by side comparison of measures of for example Fixed Salary, Variable Salary, Tax, Bonus, Overtime Payments. o    Counting of Events – E.g. converting events to fact counters so that for example the number of hires can easily be added up and compared alongside the total transfers and terminations. Multi pass processing of multiple sources e.g. headcount, salary, promotion, performance to allow side to side comparison. Adding value to data to aid analysis through banding, additional domain classifications and groupings to allow higher level analytical reporting and data discovery Calculation of complex measures examples: o    COGs, DSO, DPO, Inventory turns  etc o    Transfers within a Hierarchy or out of / into a hierarchy relative to view point in hierarchy. Configurability and Extensibility support  BI apps offer support for extensibility for various entities as automated extensibility or part of extension methodology Key Flex fields and Descriptive Flex support  Extensible attribute support (JDE)  Conformed Domains ETL Architecture BI apps offer a modular adapter architecture which allows support of multiple product lines into a single conformed model Multi Source Multi Technology Orchestration – creates load plan taking into account task dependencies and customers deployment to generate a plan based on a customers of multiple complex etl tasks Plan optimization allowing parallel ETL tasks Oracle: Bit map indexes and partition management High availability support    Follow the sun support. TCO BI apps support several utilities / capabilities that help with overall total cost of ownership and ensure a rapid implementation Improved cost of ownership – lower cost to deploy On-going support for new versions of the source application Task based setups flows Data Lineage Functional setup performed in Web UI by Functional person Configuration Test to Production support Security BI apps support both data and object security enabling implementations to quickly configure the application as per the reporting security needs Fine grain object security at report / dashboard and presentation catalog level Data Security integration with source systems  Extensible to support external data security rules Extensive Set of KPIs Over 7000 base and derived metrics across all modules Time series calculations (YoY, % growth etc) Common Currency and UOM reporting Cross subject area KPIs (analyzing HR vs GL data, drill from GL to AP/AR, etc) Prebuilt reports and dashboards 3000+ prebuilt reports supporting a large number of industries Hundreds of role based dashboards Dynamic currency conversion at dashboard level Highly tuned Performance The BI apps have been tuned over the years for both a very performant ETL and dashboard performance. The applications use best practises and advanced database features to enable the best possible performance. Optimized data model for BI and analytic queries Prebuilt aggregates& the ability for customers to create their own aggregates easily on warehouse facts allows for scalable end user performance Incremental extracts and loads Incremental Aggregate build Automatic table index and statistics management Parallel ETL loads Source system deletes handling Low latency extract with Golden Gate Micro ETL support Bitmap Indexes Partitioning support Modularized deployment, start small and add other subject areas seamlessly Source Specfic Staging and Real Time Schema Support for source specific operational reporting schema for EBS, PSFT, Siebel and JDE Application Integrations The BI apps also allow for integration with source systems as well as other applications that provide value add through BI and enable BI consumption during operational decision making Embedded dashboards for Fusion, EBS and Siebel applications Action Link support Marketing Segmentation Sales Predictor Dashboard Territory Management External Integrations The BI apps data integration choices include support for loading extenral data External data enrichment choices : UNSPSC, Item class etc. Extensible Spend Classification Broad Deployment Choices Exalytics support Databases :  Oracle, Exadata, Teradata, DB2, MSSQL ETL tool of choice : ODI (coming), Informatica Extensible and Customizable Extensible architecture and Methodology to add custom and external content Upgradable across releases

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  • Lucene and .NET Part I

    - by javarg
    I’ve playing around with Lucene.NET and trying to get a feeling of what was required to develop and implement a full business application using it. As you would imagine, many things are required for you to implement a robust solution for indexing content and searching it afterwards. Lucene is a great and robust solution for indexing content. It offers fast and performance enhanced search engine library available in Java and .NET. You will want to use this library in many particular scenarios: In Windows Azure, to support Full Text Search (a functionality not currently supported by SQL Azure) When storing files outside or not managed by your database (like in large document storage solutions that uses File System) When Full Text Search is not really what you need Lucene is more than a Full Text Search solution. It has several analyzers that let you process and search content in different ways (decomposing sentences, deriving words, removing articles, etc.). When deciding to implement indexing using Lucene, you will need to take into account the following: How content is to be indexed by Lucene and when. Using a service that runs after a specific interval Immediately when content changes When content is to available for searching / Availability of indexed content (as in real time content search) Immediately when content changes = near real time searching After a few minutes.. Ease of maintainability and development Some Technical Concerns.. When indexing content, indexes are locked for writing operations by the Index Writer. This means that Lucene is best designed to index content using single writer approach. When searching, Index Readers take a snapshot of indexes. This has the following implications: Setting up an index reader is a costly task. Your are not supposed to create one for each query or search. A good practice is to create readers and reuse them for several searches. The latter means that even when the content gets updated, you wont be able to see the changes. You will need to recycle the reader. In the second part of this post we will review some alternatives and design considerations.

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  • links for 2011-01-10

    - by Bob Rhubart
    Clusterware 11gR2: Setting up an Active/Passive failover configuration (Oracle Luxembourg XPS on Database) Some think that expensive third-party cluster systems are necessary when it comes to protecting a system with an Active/Passive architecture with failover capabilities. Not true, according to Gilles Haro. (tags: oracle otn database) Atul Kumar: Part IX : Install OAM Agent - 11g WebGate with OAM 11g Part 9 of Atul's step by step guide to the installation of Oracle Identity Management. (tags: oracle oam identitymanagement security otn) Michel Schildmeijer: Oracle Service Bus: enable / disable proxy service with WLST Amis Technology's Michel Schildmeijer shares a process he found for enabling / disabling a proxy service within Oracle Service Bus 11g with WLST (WebLogic Scripting tool). (tags: oracle soa servicebus weblogic) @andrejusb: SOA & E2.0 Partner Community Forum XIII - in Utrecht, The Netherlands Oracle ACE Director Andrejus Baranovskis shares a nice plug for the SOA & E2.0 Partner Community Forum XIII coming up in March in the Netherlands. (tags: oracle oracleace otn soa enterprise2.0) Oracle Magazine Architect Column: Enterprise Architecture in Interesting Times Oracle ACE Directors Lonneke Dikmans, Ronald van Luttikhuizen, Mike van Alst, and Floyd Teter and Oracle enterprise architect Mans Bhuller share their thoughts on the forces that are shaping enterprise architecture. (tags: oracle otn architect entarch oraclemag) InfoQ: Deriving Agility from SOA and BPM - Ten Things that Separate the Winners from the Losers In this presentation from SOA Symposium 2010, Manas Deb and Clemens Utschig-Utschig discuss how to derive business agility from SOA and BPM, motivations for agility, developing and nurturing agility, influencers and dependencies, how SOA and BPM enable agility, pitfalls and recommendations for organizational culture, and pitfalls and recommendations for business and technical architectures. (tags: ping.fm)

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  • Change the content of a <style> element through JavaScript

    - by paercebal
    The Problem I have the following code: <html> <head> <style id="ID_Style"> .myStyle { color : #FF0000 ; } </style> </head> <body> <p class="myStyle"> Hello World ! </p> </body> </html> And I want to modify the contents of <style> through JavaScript. The Expected Solution The first solution was to use the innerHTML property of the style element (retrieved through its id), but while it works on Firefox, it fails on Internet Explorer 7. So, I used pure DOM methods, that is, creating an element called style, a text node with the desired content, and append the text node as a child of the style node, etc. It fails, too. According to MSDN, the <style> element has an innerHTML property, and according to W3C, the <style> element is a HTMLStyleElement, which derives from HTMLElement, deriving from Element deriving from Node, which has the appendChild method. It seems to behave as if the content of a <style> element was readonly on Internet Explorer. The Question So the question is: Is there a way to modify the content of a <style> element on Internet Explorer? While the current problem is with IE7, a cross-browser solution would be cool, if possible. Appendix Sources: Style Element (MSDN): http://msdn.microsoft.com/en-us/library/ms535898.aspx HTMLStyleElement (W3C): http://www.w3.org/TR/2003/REC-DOM-Level-2-HTML-20030109/html.html#ID-16428977 Complete Test Code You can use this test code if you want to reproduce your problem: <html> <head> <style id="ID_Style"> .myStyle { color : #FF0000 ; } </style> <script> function replaceStyleViaDOM(p_strContent) { var oOld = document.getElementById("ID_Style") ; var oParent = oOld.parentNode ; oParent.removeChild(oOld) ; var oNew = document.createElement("style") ; oParent.appendChild(oNew) ; oNew.setAttribute("id", "ID_Style") ; var oText = document.createTextNode(p_strContent) ; oNew.appendChild(oText) ; } function replaceStyleViaInnerHTML(p_strContent) { document.getElementById("ID_Style").innerHTML = p_strContent ; } </script> <script> function setRedViaDOM() { replaceStyleViaDOM("\n.myStyle { color : #FF0000 ; }\n") } function setRedViaInnerHTML() { replaceStyleViaInnerHTML("\n.myStyle { color : #FF0000 ; }\n") } function setBlueViaDOM() { replaceStyleViaDOM("\n.myStyle { color : #0000FF ; }\n") } function setBlueViaInnerHTML() { replaceStyleViaInnerHTML("\n.myStyle { color : #0000FF ; }\n") } function alertStyle() { alert("*******************\n" + document.getElementById("ID_Style").innerHTML + "\n*******************") ; } </script> </head> <body> <div> <button type="button" onclick="alertStyle()">alert Style</button> <br /> <button type="button" onclick="setRedViaDOM()">set Red via DOM</button> <button type="button" onclick="setRedViaDOM()">set Red via InnerHTML</button> <br /> <button type="button" onclick="setBlueViaDOM()">set Blue via DOM</button> <button type="button" onclick="setBlueViaInnerHTML()">set Blue via InnerHTML</button> </div> <p class="myStyle"> Hello World ! </p> </body> </html> Thanks !

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  • How to write Haskell function to verify parentheses matching?

    - by Rizo
    I need to write a function par :: String -> Bool to verify if a given string with parentheses is matching using stack module. Ex: par "(((()[()])))" = True par "((]())" = False Here's my stack module implementation: module Stack (Stack, push, pop, top, empty, isEmpty) where data Stack a = Stk [a] deriving (Show) push :: a -> Stack a -> Stack a push x (Stk xs) = Stk (x:xs) pop :: Stack a -> Stack a pop (Stk (_:xs)) = Stk xs pop _ = error "Stack.pop: empty stack" top :: Stack a -> a top (Stk (x:_)) = x top _ = error "Stack.top: empty stack" empty :: Stack a empty = Stk [] isEmpty :: Stack a -> Bool isEmpty (Stk [])= True isEmpty (Stk _) = False So I need to implement a 'par' function that would test a string of parentheses and say if parentheses in it matches or not. How can I do that using a stack?

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  • Silverlight Listbox firing MouseRightButtonDown, but not MouseLeftButtonDown

    - by Steav
    I have this problem in a bigger Project...... so I set up a 'Testpoject' as Proof of Concept: New Silverlight-Application Add Listbox Fill listbox with a few Checkboxes Register listBox1_MouseLeftButtonDown register listBox1_MouseRightButtonDown You will see, that the listBox1_MouseLeftButtonDown won't fire under any circumstances.... listBox1_MouseRightButtonDown however fires just fine. I tried using a custom Class deriving from ListBox and overriding, assuming something in the ListBox Class was setting e.Handled = false, but this did not change the behaviour, either. Any Ideas on why this happens and how to fix? (This problem also stops the 'parent'-control from receiving the Click-Event... so the Event-passing is broke)

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  • newbie question -- how does one override show for a newtype?

    - by gatoatigrado
    I want to override the default integer constructors in Haskell so they produce strings (mostly for curiosity, but temporarily to make a nice input alternative for LaTeX's \frac{}{} inconvenience). I wanted to be able to use the language itself, instead of a special parser, but I guess that's probably not going to work out... module Main where import Prelude hiding ((+)) newtype A = A Int deriving (Eq, Show, Num) default (A) (+) :: A -> (A -> String) (A a) + (A b) = (show a) ++ " + " ++ (show b) main2 = 3+4 main :: IO () main = putStrLn main2 The problem with the above is that the + function only works for (A, A) instead of (A, String), etc. If one simply leaves out the pattern match "(A a)" and writes "a" instead, then the show() function prepends "A " so "3" becomes "A 3" instead of just "3". I want to override Show for A, but it seems to be quite a headache...

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  • Creating a castable entity class wrapper

    - by Tony
    Hi I need to have a wrapper class that exposes some properties of my entity class called ProfileEntity. I tried doing it by deriving from this entity and then creating properties that return specific entity properties, but it says I cannot cast from ProfileEntity to ProfileEntityWrapper. When I try to put the return values of a method that returns a 'ProfileEntity' into the wrapper I get the above error. How do I create such a wrapper class that is castable? Example class ProfileEntityWrapper : ProfileEntity { public string Name { get { return this.ProfileEntityName; } } public class Someclass { public ProfileEntity SomeMethod() { return ProfileEntity; // example of method returning this object } } public class SomeOtherlClass { SomeClass sc = new SomeClass(); public void DoSomething() { ProfileEntityWrapper ew = (ProfileEntityWrapper)sc.SomeMethod(); // Cannot do this cast!!! } }

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  • Reflecting derived classes in C#

    - by rook
    Let's assume there's a class with a virtual property (let's call it 'P'). It's overridden in a deriving class. Now I want to use something like this: obj.GetType().GetProperty("P") to get info about the overriding property. This search is ambigous, because there are two "P" properties (base and override). So I typed: obj.GetType().GetProperty("P", BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.Instance) It returns the overriding "P" only, but what if I can't guess in compile time if there's an override at all? The latter call would return null. The case is even more complicated, if the hierarchy of inheritance is bigger. In other words, I want to get the 'top-most' override available, otherwise - the base property. What is the cleanest way to achieve the aim? Only one I know at the moment is to go through all properties and check name and declaring type.

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  • Convert/Cast base type to Derived type

    - by user102533
    I am extending the existing .NET framework class by deriving it. How do I convert an object of base type to derived type? public class Results { //Framework methods } public class MyResults : Results { //Nothing here } //I call the framework method public static MyResults GetResults() { Results results = new Results(); //Results results = new MyResults(); //tried this as well. results = CallFrameworkMethod(); return (MyResults)results; //Throws runtime exception } I understand that this happens as I am trying to cast a base type to a derived type and if derived type has additional properties, then the memory is not allocated. When I do add the additional properties, I don't care if they are initialized to null. How do I do this without doing a manual copy?

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  • Level-order in Haskell

    - by brain_damage
    I have a structure for a tree and I want to print the tree by levels. data Tree a = Nd a [Tree a] deriving Show type Nd = String tree = Nd "a" [Nd "b" [Nd "c" [], Nd "g" [Nd "h" [], Nd "i" [], Nd "j" [], Nd "k" []]], Nd "d" [Nd "f" []], Nd "e" [Nd "l" [Nd "n" [Nd "o" []]], Nd "m" []]] preorder (Nd x ts) = x : concatMap preorder ts postorder (Nd x ts) = (concatMap postorder ts) ++ [x] But how to do it by levels? "levels tree" should print ["a", "bde", "cgflm", "hijkn", "o"]. I think that "iterate" would be suitable function for the purpose, but I cannot come up with a solution how to use it. Would you help me, please?

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