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  • Evaluate an expression tree

    - by Phronima
    Hi, This project that I'm working on requires that an expression tree be constructed from a string of single digit operands and operators both represented as type char. I did the implmentation and the program up to that point works fine. I'm able to print out the inorder, preorder and postorder traversals in the correct way. The last part calls for evaulating the expression tree. The parameters are an expression tree "t" and its root "root". The expression tree is ((3+2)+(6+2)) which is equal to 13. Instead I get 11 as the answer. Clearly I'm missing something here and I've done everything short of bashing my head against the desk. I would greatly appreciate it if someone can point me in the right direction. (Note that at this point I'm only testing addition and will add in the other operators when I get this method working.) public int evalExpression( LinkedBinaryTree t, BTNode root ) { if( t.isInternal( root ) ) { int x = 0, y = 0, value = 0; char operator = root.element(); if( root.getLeft() != null ) x = evalExpression(t, t.left( root ) ); if( root.getRight() != null ) y = evalExpression(t, t.right( root ) ); if( operator == '+' ) { value = value + Character.getNumericValue(x) + Character.getNumericValue(y); } return value; } else { return root.element(); } }

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  • StreamInsight 2.1, meet LINQ

    - by Roman Schindlauer
    Someone recently called LINQ “magic” in my hearing. I leapt to LINQ’s defense immediately. Turns out some people don’t realize “magic” is can be a pejorative term. I thought LINQ needed demystification. Here’s your best demystification resource: http://blogs.msdn.com/b/mattwar/archive/2008/11/18/linq-links.aspx. I won’t repeat much of what Matt Warren says in his excellent series, but will talk about some core ideas and how they affect the 2.1 release of StreamInsight. Let’s tell the story of a LINQ query. Compile time It begins with some code: IQueryable<Product> products = ...; var query = from p in products             where p.Name == "Widget"             select p.ProductID; foreach (int id in query) {     ... When the code is compiled, the C# compiler (among other things) de-sugars the query expression (see C# spec section 7.16): ... var query = products.Where(p => p.Name == "Widget").Select(p => p.ProductID); ... Overload resolution subsequently binds the Queryable.Where<Product> and Queryable.Select<Product, int> extension methods (see C# spec sections 7.5 and 7.6.5). After overload resolution, the compiler knows something interesting about the anonymous functions (lambda syntax) in the de-sugared code: they must be converted to expression trees, i.e.,“an object structure that represents the structure of the anonymous function itself” (see C# spec section 6.5). The conversion is equivalent to the following rewrite: ... var prm1 = Expression.Parameter(typeof(Product), "p"); var prm2 = Expression.Parameter(typeof(Product), "p"); var query = Queryable.Select<Product, int>(     Queryable.Where<Product>(         products,         Expression.Lambda<Func<Product, bool>>(Expression.Property(prm1, "Name"), prm1)),         Expression.Lambda<Func<Product, int>>(Expression.Property(prm2, "ProductID"), prm2)); ... If the “products” expression had type IEnumerable<Product>, the compiler would have chosen the Enumerable.Where and Enumerable.Select extension methods instead, in which case the anonymous functions would have been converted to delegates. At this point, we’ve reduced the LINQ query to familiar code that will compile in C# 2.0. (Note that I’m using C# snippets to illustrate transformations that occur in the compiler, not to suggest a viable compiler design!) Runtime When the above program is executed, the Queryable.Where method is invoked. It takes two arguments. The first is an IQueryable<> instance that exposes an Expression property and a Provider property. The second is an expression tree. The Queryable.Where method implementation looks something like this: public static IQueryable<T> Where<T>(this IQueryable<T> source, Expression<Func<T, bool>> predicate) {     return source.Provider.CreateQuery<T>(     Expression.Call(this method, source.Expression, Expression.Quote(predicate))); } Notice that the method is really just composing a new expression tree that calls itself with arguments derived from the source and predicate arguments. Also notice that the query object returned from the method is associated with the same provider as the source query. By invoking operator methods, we’re constructing an expression tree that describes a query. Interestingly, the compiler and operator methods are colluding to construct a query expression tree. The important takeaway is that expression trees are built in one of two ways: (1) by the compiler when it sees an anonymous function that needs to be converted to an expression tree, and; (2) by a query operator method that constructs a new queryable object with an expression tree rooted in a call to the operator method (self-referential). Next we hit the foreach block. At this point, the power of LINQ queries becomes apparent. The provider is able to determine how the query expression tree is evaluated! The code that began our story was intentionally vague about the definition of the “products” collection. Maybe it is a queryable in-memory collection of products: var products = new[]     { new Product { Name = "Widget", ProductID = 1 } }.AsQueryable(); The in-memory LINQ provider works by rewriting Queryable method calls to Enumerable method calls in the query expression tree. It then compiles the expression tree and evaluates it. It should be mentioned that the provider does not blindly rewrite all Queryable calls. It only rewrites a call when its arguments have been rewritten in a way that introduces a type mismatch, e.g. the first argument to Queryable.Where<Product> being rewritten as an expression of type IEnumerable<Product> from IQueryable<Product>. The type mismatch is triggered initially by a “leaf” expression like the one associated with the AsQueryable query: when the provider recognizes one of its own leaf expressions, it replaces the expression with the original IEnumerable<> constant expression. I like to think of this rewrite process as “type irritation” because the rewritten leaf expression is like a foreign body that triggers an immune response (further rewrites) in the tree. The technique ensures that only those portions of the expression tree constructed by a particular provider are rewritten by that provider: no type irritation, no rewrite. Let’s consider the behavior of an alternative LINQ provider. If “products” is a collection created by a LINQ to SQL provider: var products = new NorthwindDataContext().Products; the provider rewrites the expression tree as a SQL query that is then evaluated by your favorite RDBMS. The predicate may ultimately be evaluated using an index! In this example, the expression associated with the Products property is the “leaf” expression. StreamInsight 2.1 For the in-memory LINQ to Objects provider, a leaf is an in-memory collection. For LINQ to SQL, a leaf is a table or view. When defining a “process” in StreamInsight 2.1, what is a leaf? To StreamInsight a leaf is logic: an adapter, a sequence, or even a query targeting an entirely different LINQ provider! How do we represent the logic? Remember that a standing query may outlive the client that provisioned it. A reference to a sequence object in the client application is therefore not terribly useful. But if we instead represent the code constructing the sequence as an expression, we can host the sequence in the server: using (var server = Server.Connect(...)) {     var app = server.Applications["my application"];     var source = app.DefineObservable(() => Observable.Range(0, 10, Scheduler.NewThread));     var query = from i in source where i % 2 == 0 select i; } Example 1: defining a source and composing a query Let’s look in more detail at what’s happening in example 1. We first connect to the remote server and retrieve an existing app. Next, we define a simple Reactive sequence using the Observable.Range method. Notice that the call to the Range method is in the body of an anonymous function. This is important because it means the source sequence definition is in the form of an expression, rather than simply an opaque reference to an IObservable<int> object. The variation in Example 2 fails. Although it looks similar, the sequence is now a reference to an in-memory observable collection: var local = Observable.Range(0, 10, Scheduler.NewThread); var source = app.DefineObservable(() => local); // can’t serialize ‘local’! Example 2: error referencing unserializable local object The Define* methods support definitions of operator tree leaves that target the StreamInsight server. These methods all have the same basic structure. The definition argument is a lambda expression taking between 0 and 16 arguments and returning a source or sink. The method returns a proxy for the source or sink that can then be used for the usual style of LINQ query composition. The “define” methods exploit the compile-time C# feature that converts anonymous functions into translatable expression trees! Query composition exploits the runtime pattern that allows expression trees to be constructed by operators taking queryable and expression (Expression<>) arguments. The practical upshot: once you’ve Defined a source, you can compose LINQ queries in the familiar way using query expressions and operator combinators. Notably, queries can be composed using pull-sequences (LINQ to Objects IQueryable<> inputs), push sequences (Reactive IQbservable<> inputs), and temporal sequences (StreamInsight IQStreamable<> inputs). You can even construct processes that span these three domains using “bridge” method overloads (ToEnumerable, ToObservable and To*Streamable). Finally, the targeted rewrite via type irritation pattern is used to ensure that StreamInsight computations can leverage other LINQ providers as well. Consider the following example (this example depends on Interactive Extensions): var source = app.DefineEnumerable((int id) =>     EnumerableEx.Using(() =>         new NorthwindDataContext(), context =>             from p in context.Products             where p.ProductID == id             select p.ProductName)); Within the definition, StreamInsight has no reason to suspect that it ‘owns’ the Queryable.Where and Queryable.Select calls, and it can therefore defer to LINQ to SQL! Let’s use this source in the context of a StreamInsight process: var sink = app.DefineObserver(() => Observer.Create<string>(Console.WriteLine)); var query = from name in source(1).ToObservable()             where name == "Widget"             select name; using (query.Bind(sink).Run("process")) {     ... } When we run the binding, the source portion which filters on product ID and projects the product name is evaluated by SQL Server. Outside of the definition, responsibility for evaluation shifts to the StreamInsight server where we create a bridge to the Reactive Framework (using ToObservable) and evaluate an additional predicate. It’s incredibly easy to define computations that span multiple domains using these new features in StreamInsight 2.1! Regards, The StreamInsight Team

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  • .NET XPath Returns No Results

    - by Stacy Vicknair
    When using XPath in .NET one of the gotchas to be aware of is that all namespaces must be named, otherwise you’ll end up with no results. Default namespaces that are specified with xmlns alone still need to be recognized in the XPath query! Say I had a bit of XML like what is returned from the QueryService web service in Sharepoint: 1: <?xml version="1.0" encoding="UTF-8"?> 2: <ResponsePacket xmlns="urn:Microsoft.Search.Response"> 3: <Response> 4: <Range> 5: ... 6: <Results> 7: <Document xmlns="urn:Microsoft.Search.Response.Document" relevance="849"> 8: ...   When consuming and navigating this response with XPath it is necessary to name all namespaces. Then those named namespaces must be used in reference to the individual element being requested (i.e. doc:Document). In VB: 1: Dim xdoc = new XPathDocument(reader) 2: Dim nav = xdoc.CreateNavigator() 3: Dim nsMgr = new XmlNamespaceManager(nav.NameTable) 4: nsMgr.AddNamespace("resp", "urn:Microsoft.Search.Response") 5: nsMgr.AddNamespace("doc", "urn:Microsoft.Search.Response.Document") 6:  7: Dim results = nav.Select("//doc:Document", nsMgr)   In C#: 1: var xdoc = new XPathDocument(reader); 2: var nav = xdoc.CreateNavigator(); 3: var nsMgr = new XmlNamespaceManager(nav.NameTable); 4:  5: nsMgr.AddNamespace("resp", "urn:Microsoft.Search.Response"); 6: nsMgr.AddNamespace("doc", "urn:Microsoft.Search.Response.Document"); 7:  8: var results = nav.Select("//doc:Document", nsMgr);

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  • Regular expression for Regular expressions?

    - by kavoir.com
    I have an app that enables the user to input a regular expression, my question is how to check against any input of regular expressions and make sure they are valid ones because if they are not there will be preg_match errors. I don't want to use the '@' before preg_match, so if there's a way to check the validity of the user input of regular expressions that'd be great. The regular expression system of PHP seems to be rather too complicated for me to come up with a regular expression for them. Any idea or any alternatives would be possible in achieving this?

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  • Working with expression AST:s

    - by Marcus
    Hi, Is there any best practice when working with AST:s? I have a parsed expression AST. ConstantExpression, BinaryExpression etc. I want to populate a GUI-dialog with information from the AST, and it's here where I get kinda confused because my code gets pretty messy. Example: expression = "Var1 > 10 AND Var2 < 20" I want to populate two textboxes with value 10 resp. 20 from the AST. What I'm doing now is a recursive method that checks for correct child expression-types (with .Net Is-operator) and acts accordingly and the code is really "smelly" :) Is there any design pattern, like Visitor or such, that makes this somewhat easier/more readable/maintainable ?

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  • Grabbing values from Expression.Blend.SampleData

    - by Mitchell Skurnik
    I am trying to figure out how to grab a value from Expression.Blend.SampleData. If my id is equal to a drop down for example, I can grab it by doing this: ((Expression.Blend.SampleData.MyDatabase.something)(MyDropDown.SelectedItem)).description; I need some way to place my own value where (MyDropDown.SelectedItem) is. Visual studio wants me to convert it a "Expression.Blend.SampleData.MyDatabase.something" format. I have tried a few ways to do this but I have been unsuccessful. Any Ideas? EDIT I am starting to think there is no way in Silverlight to do this

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  • Reverse Expression.Like criterion

    - by Joel Potter
    How should I go about writing a backwards like statement using NHibernate criteria? WHERE 'somestring' LIKE [Property] + '%' Sub Question: Can you access the abstract root alias in a SQLCriterion expression? This is somewhat achievable using the SQLCriterion expression Expression.Sql("? like {alias}.[Property] + '.%'", value, NHibernateUtil.String); However, in the case of class inheritance, {alias} is replaced with the incorrect alias for the column. Example (these classes are stored in separate tables): public abstract class Parent { public virtual string Property { get; set; } } public class Child : Parent { } The above query executed with Child as the root type will replace {alias} with the alias to the Child table rather than the Parent table. This results in an invalid column exception. I need to execute a like statement as above where the property exists on the parent table rather than on the root type table.

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  • How do I get values of Linq Expression

    - by Yucel
    Hi, I have a method that takes Expression type parameter, in my method i want to get values of this expression but cant find out hot to do that. private User GetUser(Expression<Func<User, bool>> query) { User user = Context.User.Where(query).FirstOrDefault(); return user; } I am calling this method with different parameters like GetUser(u => u.Username == username); GetUser(u=> u.Email == email); I want to change GetUser method to work with stored procedures but i need to find what is inside query parameter I want to check if query is u.Username == username I will call GetUserByUsername SP if query is u.Email == email I will call GetuserByEmail SP

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  • VB.NET logical expression evaluator

    - by Tim
    I need to test a logical expression held in a string to see if it evaluate to TRUE or FALSE.(the strig is built dynamically) For example the resulting string may contain "'dog'<'cat' OR (14 AND 4<6)". There are no variables in the string, it will logically evaluate. It will only contain simple operators = < < = <= and AND , OR and Open and Close Brackets, string constants and numbers. (converted to correct syntax && || etc.) I currently acheive this by creating a jscipt function and compiling it into a .dll. I then reference the .dll in my VB.NET project. class ExpressionEvaluator { function Evaluate(Expression : String) { return eval(Expression); } } Is there a simpler method using built in .NET functions or Lamdba expressions.

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  • Regular Expression for exclude something that has specific word inside bracked (MySQL)

    - by bn
    This Regular expression if for MySQL query: I want to exclude this row because it has 'something' in side the bracket "bla bla bla bla bla bla (bla bla bla something)" However I want to include this row, because it does not have 'something' inside the bracket "bla bla bla (bla bla bla)" I tried this query but it didnt work. SELECT * FROM table WHERE field NOT REGEXP '((%something%))'; I think this is wrong, I just did trial and error, I like to use regular expression, but never understand it completely. is there any good tutorial/books/links for learning the detail of regular expression? Thank You

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  • difference between Casini [IIS express] and VS Development server or Expression web

    - by anirudha
    MVC3 project can be run within Expression web and Visual studio as opened like a website not a project. they work same even if you open blogengine.net project in VS they take a time when you have more theme but expression web debug them in a second. well because theme design not matter for code. Expression web is a good because they save time for compile the code. even changes we make a little in design nothing in backend code.   i found a little difference between Casini and VS development server that if image putted in wrong way like <img src=”//img.png”/> instead of <img src=”/img.png”/> the error we make // instead of / that’s not worked in Expression web or Visual studio debugging but in Cassini it’s work fine.   Well i found that debug Blogengine.net in Expression web is a great thing because in VS they take a time like a minute to debug when you trying to debug first time. Expression Web save a time when we design themes within them and that’s much good option because web is also maked for design.   Well if you want to debug application faster then use casini but Expression web debugging is a good option when they take a long time to debug in Visual studio and EW debug them in a seconds.

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  • Excel Matching problem with logic expression

    - by abelenky
    I have a block of data that represents the steps in a process and the possible errors: ProcessStep Status FeesPaid OK FormRecvd OK RoleAssigned OK CheckedIn Not Checked In. ReadyToStart Not Ready for Start I want to find the first Status that is not "OK". I have attempted this: =Match("<>""OK""", StatusRange, 0) which is supposed to return the index of the first element in the range that is NOT-EQUAL (<) to "OK" But this doesn't work, instead returning #N/A. I expect it to return 4 (index #4, in a 1-based index, representing that CheckedIn is the first non-OK element) Any ideas how to do this?

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  • HtmlAgilityPack SelectNodes expression to ignore an element with a certain attribute

    - by thaky
    I am trying to select nodes except from script nodes and a ul that has a class called 'relativeNav'. Can someone please direct me to the right path? I have been searching for this for a week and I can't find it anywhere. Currently I have this but it obviously selecting the //ul[@class='relativeNav'] as well. Is there anyway to put an NOT expression of it so that SelectNode will ignore that one? foreach (HtmlNode node in doc.DocumentNode.SelectNodes("//body//*[not(self::script)]/text()")) { Console.WriteLine("Node: " + node); singleString += node.InnerText.Trim() + "\n"; }

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  • strange UnindexedFileException for Expression Encoder MediaItem

    - by George2
    Hello everyone, When I use the following statement to create a new instance of MediaItem (VSTS 2008 + .Net 3.5 + C# + Windows 7), and I met with the following exception, any ideas what is wrong? I have tried with other wmv files, and there are no such issues. BTW: I am using Expression Encoder 3 SDK. MediaItem video = new MediaItem("1.wmv"); Microsoft.Expression.Encoder.UnindexedFileException {"Cannot seek file."} thanks in advance, George

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  • PostgreSQL - can't save items - "type integer but expression is of type character"

    - by user984621
    I am getting still over and over again this error, the column age has the type integer, I am saving into this column integer-value, I also tried to don't save nothing into this column, but still getting this error... Could anyone help me, how to fix that? PG::Error: ERROR: column "age" is of type integer but expression is of type character varying at character 102 HINT: You will need to rewrite or cast the expression. : INSERT INTO "user_details" ("created_at", "age", "updated_at", "user_id") VALUES ($1, $2, $3, $4) RETURNING "id"

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  • Reporting Services Expression

    - by Alex
    I'm trying to set the Hidden-property of a Textbox based on this expression: =IIf(IsNothing(Parameters!customer_numbers.Value) AND IsNothing(Parameters!country_codes.Value),False,True) Error: "Argument not specified for parameter 'FalsePart' of Public Function IIf(Expression As Boolean, TruePart As Object, FalsePart As Object) As Object" I'm a jScript/C# guy and not used to this pseudo-VB language. What is wrong? Regards Alex

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  • php regular expression assistance bold a filename

    - by jason
    I am not very good, with regular expression in php I am trying to get a reg_expression to find all file names such as /file-name-here.php and make it bold. This expression works in Flash but not in php it also doesn't accept the '-' i'm not sure why i can't get it to work with preg_replace /(https?://)?(www\.)?([a-zA-Z0-9_%]*)\b\.[a-z]{2,4}(\.[a-z]{2})?((/[a-zA-Z0-9_%]*)+)?(\.[a-z]*)?/g

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  • Expression 4 ships

    - by guybarrette
    The Expression 4 suite of products shipped today.  Good news, it’s a free upgrade for Expression 3 owners. New with version 4 is the Expression Studio 4 Web Professional suite.  Basically, it’s Expression Studio 4 Ultimate without Blend and SketchFlow. var addthis_pub="guybarrette";

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  • Render an url of type ?x=1&y=2 with xslt

    - by Josemalive
    Hello, Im trying to print, using a xslt sheet a url but im having problems with the chars = and &: This is the url that i want to render: <a href="whatever.aspx?x=1&y=2">whatever</a> Im getting that "=" is an unexpected token. How should i have to put the = and the & in a xslt sheet? Thanks in advance. Regards. Jose

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  • Convert Javascript Regular Expression to PHP (PCRE) Expression

    - by Matt
    Hi all, I am up to my neck in regular expressions, and I have this regular expression that works in javascript (and flash) that I just can't get working in PHP Here it is: var number = '(?:-?\\b(?:0|[1-9][0-9]*)(?:\\.[0-9]+)?(?:[eE][+-]?[0-9]+)?\\b)'; var oneChar = '(?:[^\\0-\\x08\\x0a-\\x1f\"\\\\]' + '|\\\\(?:[\"/\\\\bfnrt]|u[0-9A-Fa-f]{4}))'; var str = '(?:\"' + oneChar + '*\")'; var varName = '\\$(?:' + oneChar + '[^ ,]*)'; var func = '(?:{[ ]*' + oneChar + '[^ ]*)'; // Will match a value in a well-formed JSON file. // If the input is not well-formed, may match strangely, but not in an unsafe // way. // Since this only matches value tokens, it does not match whitespace, colons, // or commas. var jsonToken = new RegExp( '(?:false|true|null' +'|[\\}]' + '|' + varName + '|' + func + '|' + number + '|' + str + ')', 'g'); If you want it fully assembled here it is: /(?:false|true|null|[\}]|\$(?:(?:[^\0-\x08\x0a-\x1f"\\]|\\(?:["/\\bfnrt]|u[0-9A-Fa-f]{4}))[^ ,]*)|(?:{[ ]*(?:[^\0-\x08\x0a-\x1f"\\]|\\(?:["/\\bfnrt]|u[0-9A-Fa-f]{4}))[^ ]*)|(?:-?\b(?:0|[1-9][0-9]*)(?:\.[0-9]+)?(?:[eE][+-]?[0-9]+)?\b)|(?:"(?:[^\0-\x08\x0a-\x1f"\\]|\\(?:["/\\bfnrt]|u[0-9A-Fa-f]{4}))*"))/g Interestingly enough, its very similar to JSON. I need this regular expression to work in PHP... Here's what I have in PHP: $number = '(?:-?\\b(?:0|[1-9][0-9]*)(?:\\.[0-9]+)?(?:[eE][+-]?[0-9]+)?\\b)'; $oneChar = '(?:[^\\0-\\x08\\x0a-\\x1f\"\\\\]|\\\\(?:[\"/\\\\bfnrt]|u[0-9A-Fa-f]{4}))'; $string = '(?:\"'.$oneChar.'*\")'; $varName = '\\$(?:'.$oneChar.'[^ ,]*)'; $func = '(?:{[ ]*'.$oneChar.'[^ ]*)'; $jsonToken = '(?:false|true|null' .'|[\\}]' .'|'.$varName .'|'.$func .'|'.$number .'|'.$string .')'; echo $jsonToken; preg_match_all($jsonToken, $content, $out); return $out; Here's what happens if I try using preg_match_all(): Warning: preg_match_all() [function.preg-match-all]: Compilation failed: nothing to repeat at offset 0 in /Users/Matt/Sites/Templating/json/Jeeves.php on line 88 Any help would be much appreciated! Thanks, Matt

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  • d:DesignData issue, Visual Studio 2010 cant build after adding sample design data with Expression Bl

    - by Valko
    Hi, VS 2010 solution and Silverlight project builds fine, then: I open MyView.xaml view in Expression Blend 4 Add sample data from class (I use my class defined in the same project) after I add new sample design data with Expression blend 4, everything looks fine, you see the added sample data in the EB 4 fine, you also see the data in VS 2010 designer too. Close the EB 4, and next VS 2010 build is giving me this errors: Error 7 XAML Namespace http://schemas.microsoft.com/expression/blend/2008 is not resolved. C:\Code\source\...myview.xaml and: Error 12 Object reference not set to an instance of an object. ... TestSampleData.xaml when I open the TestSampleData.xaml I see that namespace for my class used to define sample data is not recognized. However this namespace and the class itself exist in the same project! If I remove the design data from the MyView.xaml: d:DataContext="{d:DesignData /SampleData/TestSampleData.xaml}" it builds fine and the namespace in TestSampleData.xaml is recognized this time?? and then if add: d:DataContext="{d:DesignData /SampleData/TestSampleData.xaml}" I again see in the VS 2010 designer sample data, but the next build fails and again I see studio cant find the namespace in my TestSampleData.xaml containing sample data. That cycle is driving me crazy. Am I missing something here, is it not possible to have your class defining sample design data in the same project you have the MyView.xaml view?? cheers Valko

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  • Dynamic expression tree how to

    - by Savvas Sopiadis
    Hello everybody! Implemented a generic repository with several Methods. One of those is this: public IEnumerable<T> Find(Expression<Func<T, bool>> where) { return _objectSet.Where(where); } Given to be it is easy to call this like this: Expression<Func<Culture, bool>> whereClause = c => c.CultureId > 4 ; return cultureRepository.Find(whereClause).AsQueryable(); But now i see (realize) that this kind of quering is "limiting only to one criteria". What i would like to do is this: in the above example c is of type Culture. Culture has several properties like CultureId, Name, Displayname,... How would i express the following: CultureId 4 and Name.contains('de') and in another execution Name.contains('us') and Displayname.contains('ca') and .... Those queries should be created dynamically. I had a look in Expression trees (as i thought this to be a solution to my problem - btw i never used them before) but i cannot find anything which points to my requirement. How can this be costructed? Thanks in advance

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  • How best to use XPath with very large XML files in .NET?

    - by glenatron
    I need to do some processing on fairly large XML files ( large here being potentially upwards of a gigabyte ) in C# including performing some complex xpath queries. The problem I have is that the standard way I would normally do this through the System.XML libraries likes to load the whole file into memory before it does anything with it, which can cause memory problems with files of this size. I don't need to be updating the files at all just reading them and querying the data contained in them. Some of the XPath queries are quite involved and go across several levels of parent-child type relationship - I'm not sure whether this will affect the ability to use a stream reader rather than loading the data into memory as a block. One way I can see of making it work is to perform the simple analysis using a stream-based approach and perhaps wrapping the XPath statements into XSLT transformations that I could run across the files afterward, although it seems a little convoluted. Alternately I know that there are some elements that the XPath queries will not run across, so I guess I could break the document up into a series of smaller fragments based on it's original tree structure, which could perhaps be small enough to process in memory without causing too much havoc. I've tried to explain my objective here so if I'm barking up totally the wrong tree in terms of general approach I'm sure you folks can set me right...

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