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  • C++ Expression Templates

    - by yCalleecharan
    Hi, I currently use C for numerical computations. I've heard that using C++ Expression Templates is better for scientific computing. What are C++ Expression Templates in simple terms? Are there books around that discuss numerical methods/computations using C++ Expression Templates? In what way, C++ Expression Templates are better than using pure C? Thanks a lot

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  • C++ WCHAR: Cannot allocate an array of constant size 0

    - by Rosarch
    I'm trying to create a WCHAR: LONG bufferSize = foo.bar() + 1; WCHAR wszBaz[bufferSize]; The compiler issues an error: error C2057: expected constant expression error C2466: cannot allocate an array of constant size 0 error C2133: 'wszBaz' unknown size What am I doing wrong? UPDATE: I added const but it still gives the same error: const LONG bufferSize = foo.bar() + 1; WCHAR wszBaz[bufferSize];

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  • Why isn't Expression Blend rendering my User Control? It's only showing XAML.

    - by unforgiven3
    I'm opening valid XAML within my VS2008 solution in Expression Blend 3 and it is only showing XAML when I try to open individual XAML files. My solution/projects all build and run correctly. When I go to View - Active Document View the Design View, Split View and XAML View options are all grayed out... which doesn't make much sense. I'm not much of a Blend user, but this has never happened before, and I'm coming up blank for how to fix it. Any ideas?

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  • How can I generate an Expression tree that queries an object with List<T> as a property?

    - by David Robbins
    Forgive my clumsy explanation, but I have a class that contains a List: public class Document { public int OwnerId { get; set; } public List<User> Users { get; set; } public Document() { } } public class User { public string UserName { get; set; } public string Department { get; set; } } Currently I use PredicateBuilder to perform dynmica queries on my objects. How can I turn the following LINQ statement into an Expression Tree: var predicate= PredicateBuilder.True<User>(); predicate= predicate.And<User>(user => user.Deparment == "HR"); var deptDocs = documents.AsQueryable() .Where(doc => doc.Users .AsQueryable().Count(predicate) > 0) .ToList(); In other words var deptDocs = documents.HasUserAttributes("Department", "HR").ToList();

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  • Expression Encoder - Limitations for file Dimension - min size of 64 * 64 and must be a multiple of

    - by PortageMonkey
    I receive error messages when attempting to encode files in Expression Encoder when the file width or height is not a multiple of four, or is smaller than 64. I have been able to find very little in the documentation / web searches on this, and nothing that explains what settings may cause / alleviate these limitations. I assume it has something to do with the underlying data type. Error Message: Invalid Width Specified. The value must be an integer between 64 - and 4096 and be a multiple of 4. Can anyone provide further details on why / what settings can be manipulated to change this behavior: I.E. quality, compression etc.

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  • How to resize a group of vectors in Expression Blend/WPF/Silverlight ?

    - by Shnitzel
    So say for example I created a few small squares in expression blend. I then group them together by selecting them, right clicking and selecting "Group Into - Grid" So now that they are in the grid, I'd like to be able to resize this grid and then they would resize but it doesn't happen, it just resizes the grid but leaves the vectors the same. Is there a way to do what I am looking for? p.s I know you can just select all the vectors and then resize them all, but I am looking for a way to just resize one container and not all the objects in there..

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  • WPF: In Expression Blend, how to change Foreground of a custom button with a Border on different states?

    - by SubmarineX
    In Expression Blend 4, I want to change the Foreground of a custom button on different states. I'm just able to change the Background and BorderBrush. Just like this: If the state is "Normal", the color of text "Button" is Black, while the state is "Pressed", the color of text "Button" is White. On Brushes Panel under Properties Panel, there're 3 properties but no Foreground property: Who can help me? I'm so perplexed. Edit I find ContentControl have a Foreground property, but ContentPresenter haven't. Wether I should use ContentControl instead of ContentPresenter?

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  • What is the difference between Constant Vertex Attributes and Uniforms?

    - by Samaursa
    According to the OpenGL ES 2.0 Programming Guide: A constant vertex attribute is the same for all vertices of a primitive, and therefore only one value needs to be specified for all the vertices of a primitive. For uniforms the book states: ...any parameter to a shader that is constant across either all vertices or fragments (but that is not known at compile time) should be passed in as a uniform. I've always used uniforms for data that is constant for a primitive but now it appears that attributes can also be used in the same way. Is there more to constant vertex attribute than simply 'they are the same as uniforms'?

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  • Wrong assembly-references for Silverlight Sketchflow project in Blend 3

    - by persistent
    Hello, In my installation of Blend 3, the SketchStyles are missing when a new project is created. I found out that this is because the following automatic references in the project are wrong: Microsoft.Expression.Interactions Microsoft.Expression.Prototyping.Interactivity Microsoft.Expression.Prototyping.RunTime Microsoft.Expression.Prototyping.SketchControls In the project references these all point to my project path (where they don't live). If I remove them manually, and instead set the references to ie this: "c:\Program Files (x86)\Microsoft SDKs\Expression\Blend 3\Interactivity\Libraries\Silverlight\Microsoft.Expression.Interactions.dll" everything works. Any ideas on why, and how to fix this? Could it be the project template somehow? TIA

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  • C++ infix to postfix conversion for logical conditions

    - by Gopalakrishnan Subramani
    I want to evaluate one expression in C++. To evaluate it, I want the expression to be converted to prefix format. Here is an example wstring expression = "Feature1 And Feature2"; Here are possible ways. expression = "Feature1 And (Feature2 Or Feature3)"; expression = "Not Feature1 Or Feature3"; Here And, Or, Not are reserved words and parentheses ("(", )) are used for scope Not has higher precedence And is set next precedence to Not Or is set to next precedence to And WHITE SPACE used for delimiter. Expression has no other elements like TAB, NEWLINE I don't need arithmetic expressions. I can do the evaluation but can somebody help me to convert the strings to prefix notation?

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  • Watchguard Firewall WebBlocker Regular Expression for Multiple Domains?

    - by Eric
    I'm pretty sure this is really a regex question, so you can skip to REGEX QUESTION if you want to skip the background. Our primary firewall is a Watchguard X750e running Fireware XTM v11.2. We're using webblocker to block most of the categories, and I'm allowing needed sites as they arise. Some sites are simple to add as exceptions, like Pandora radio. That one is just a pattern matched exception with "padnora.com/" as the pattern. All traffic from anywhere on pandora.com is allowed. I'm running into trouble on more sophisticated domains that reference content off of their base domains. We'll take GrooveShark as a sample. If you go to http://grooveshark.com/ and view page source, you'll see hrefs referring to gs-cdn.net as well as grooveshar.com. So adding a WebBlocker exception to grooveshark.com/ is not effective, and I have to add a second rule allowing gs-cdn.net/ as well. I see that the WebBlocker allows regex rules, so what I'd like to do in situations like this is create a single regex rule that allows traffic to all the needed domains. REGEX QUESTION: I'd like to try a regex that matches grooveshark.com/ and gs-cdn.net/. If anybody can help me write that regex, I'd appreciate it. Here is what is in the WatchGuard documentation from that section: Regular expression Regular expression matches use a Perl-compatible regular expression to make a match. For example, .[onc][eor][gtm] matches .org, .net, .com, or any other three-letter combination of one letter from each bracket, in order. Be sure to drop the leading “http://” Supports wild cards used in shell script. For example, the expression “(www)?.watchguard.[com|org|net]” will match URL paths including www.watchguard.com, www.watchguard.net, and www.watchguard.org. Thanks all!

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  • How do I optimize this postfix expression tree for speed?

    - by Peter Stewart
    Thanks to the help I received in this post: I have a nice, concise recursive function to traverse a tree in postfix order: deque <char*> d; void Node::postfix() { if (left != __nullptr) { left->postfix(); } if (right != __nullptr) { right->postfix(); } d.push_front(cargo); return; }; This is an expression tree. The branch nodes are operators randomly selected from an array, and the leaf nodes are values or the variable 'x', also randomly selected from an array. char *values[10]={"1.0","2.0","3.0","4.0","5.0","6.0","7.0","8.0","9.0","x"}; char *ops[4]={"+","-","*","/"}; As this will be called billions of times during a run of the genetic algorithm of which it is a part, I'd like to optimize it for speed. I have a number of questions on this topic which I will ask in separate postings. The first is: how can I get access to each 'cargo' as it is found. That is: instead of pushing 'cargo' onto a deque, and then processing the deque to get the value, I'd like to start processing it right away. I don't yet know about parallel processing in c++, but this would ideally be done concurrently on two different processors. In python, I'd make the function a generator and access succeeding 'cargo's using .next(). But I'm using c++ to speed up the python implementation. I'm thinking that this kind of tree has been around for a long time, and somebody has probably optimized it already. Any Ideas? Thanks

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  • List of events triggered on pages matching regex

    - by Cubius
    Is there a way to get the grouped list of events (such as in Top events) which were triggered on pages matching a regular expression? I may add the Page secondary dimension in Top events and apply the regex filter but this way I won't get a grouped list. I may apply the filter to Events - Pages report but this way the events will be grouped only inside pages whilst I need global grouping. Any suggestions?

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  • How to use SQL Expression Fields of Crystal Report 11.5 from VB.NET 2008

    - by Tareq
    I have the following SQL Expression Field in my Crystal Report 11.5 {fn CONCAT({fn CONCAT("SPR_PRODUCT"."PRODUCT_ID","SPR_PRODUCT_SUB_ITEM"."P_SUB_ITEM_ID" )},{fn CONCAT("SPR_PRODUCT_ITEM"."P_ITEM_ID","SPR_PRODUCT_GROUP"."P_GROUP_ID" )} )} It works well in the Preview Mode. But when I use the report in my VB.NET 2008 Project it says the following: Error in compiling SQL Expression : SQL Expressions can not be used in this report.. Error in File <...>.rpt: SQL Expression error: Error in compiling SQL Expression : SQL Expressions can not be used in this report... Please help me by telling how can I use the SQL Expression field in VB.NET ? Thanks in Advance.

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  • Regular expression to validate name in .NET multilingual web application

    - by BT
    Hi, how can i write a regular expression to validate name field in a multilingual web application, i want to validate the name field for non-English languages e.g. Spanish or German, and we need to make sure that no one enter digits or special characters. I'm using .NET. I believe we can't use expression as below for non-English language. ^[a-zA-Z]{1,20}$ Any help will be highly appreciated! Solution: I'm using this regular expression ^\p{L}[\p{L}\p{Pd}\x27]*\p{L}$ , and the below MSISDN article was very helpful: MSDN - Regular Expression Also below tool is very helpful, in validating your regular expression: Regex Builder

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  • How to Expression.Invoke an arbitrary LINQ 2 SQL Query

    - by Remus Rusanu
    Say I take an arbitrary LINQ2SQL query's Expression, is it possible to invoke it somehow? MyContext ctx1 = new MyContext("..."); var q = from t in ctx1.table1 where t.id = 1 select t; Expression qe = q.Expression; var res = Expression.Invoke(qe); This throws ArgumentException "Expression of type System.Linq.IQueryable`1[...]' cannot be invoked". My ultimate goal is to evaluate the same query on several different data contexts.

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  • Given a Member Access lambda expression, convert it to a specific string representation with full ac

    - by Nathan
    Given an Expression<Func<T, object>> (e.g. x = x.Prop1.SubProp), I want to create a string "Prop1.SubProp" for as deep as necessary. In the case of a single access (e.g. x = x.Prop1), I can easily do this with: MemberExpression body = (expression.Body.NodeType == ExpressionType.Convert) ? (MemberExpression)((UnaryExpression)expression.Body).Operand : (MemberExpression)expression.Body; return body.Member.Name; However, if there is deeper nesting, e.g. x = x.Prop1.SubProp1, this only gets the most deeply nested name, e.g. "SubProp1" instead of "Prop1.SubProp1" Is there anyway to access the full property path of a lambda expression?

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  • Evaluate a string-expression in XSL

    - by Jerzakie
    Is there any way to evaluate a string expression in XSL? example: <myItem id="1"> <validator expression="$someVariable = '3'" /> </myItem> ... <xsl:variable name="someVariable" select="3" /> <xsl:if test="@expression"> ... I realize this syntax does not work the way I want it to, but is there any way to store the test expression in a variable and then evaluate the expression?

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  • C++ : Declaring the array size with a non-constant variable

    - by Jérôme
    I always thought that when declaring an array in C++, the size has to be a constant integer value. For instance : int MyArray[5]; // correct or const int ARRAY_SIZE = 6; int MyArray[ARRAY_SIZE]; // correct but int ArraySize = 5; int MyArray[ArraySize]; // incorrect Here is also what is explained in The C++ Programming Language, by Bjarne Stroustrup : The number of elements of the array, the array bound, must be a constant expression (§C.5). If you need variable bounds, use a vector(§3.7.1, §16.3). For example: void f(int i) { int v1[i]; // error : array size not a constant expression vector<int> v2[i]; // ok } But to my big surprise, the code above does compile fine on my system ! Here is what I tried to compile : void f(int i) { int v2[i]; } int main() { int i = 3; int v1[i]; f(5); } I got no error ! I'm using GCC v4.4.0. Is there something I'm missing ?

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  • Expression web ftp: Stuck at "Listing subsites"

    - by FrankPython
    When I try to use the Expression Web 4 built-in ftp I see the message ""Listing subsites in.." and soon afterward "passive ftp not available". If I switch to active, I get "active ftp not available". There are no subsites. It is a simple directory with one html page. Backend is a normal IIS6 server. FTP to the same IP with other FTP clients works fine! Any idea if Expression web has some specific requirements? It is our own dedicated server. (Please no tips to use another tool, for this specific project Expression Web is a requirement).

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  • Converting a Linq expression tree that relies on SqlMethods.Like() for use with the Entity Framework

    - by JohnnyO
    I recently switched from using Linq to Sql to the Entity Framework. One of the things that I've been really struggling with is getting a general purpose IQueryable extension method that was built for Linq to Sql to work with the Entity Framework. This extension method has a dependency on the Like() method of SqlMethods, which is Linq to Sql specific. What I really like about this extension method is that it allows me to dynamically construct a Sql Like statement on any object at runtime, by simply passing in a property name (as string) and a query clause (also as string). Such an extension method is very convenient for using grids like flexigrid or jqgrid. Here is the Linq to Sql version (taken from this tutorial: http://www.codeproject.com/KB/aspnet/MVCFlexigrid.aspx): public static IQueryable<T> Like<T>(this IQueryable<T> source, string propertyName, string keyword) { var type = typeof(T); var property = type.GetProperty(propertyName); var parameter = Expression.Parameter(type, "p"); var propertyAccess = Expression.MakeMemberAccess(parameter, property); var constant = Expression.Constant("%" + keyword + "%"); var like = typeof(SqlMethods).GetMethod("Like", new Type[] { typeof(string), typeof(string) }); MethodCallExpression methodExp = Expression.Call(null, like, propertyAccess, constant); Expression<Func<T, bool>> lambda = Expression.Lambda<Func<T, bool>>(methodExp, parameter); return source.Where(lambda); } With this extension method, I can simply do the following: someList.Like("FirstName", "mike"); or anotherList.Like("ProductName", "widget"); Is there an equivalent way to do this with Entity Framework? Thanks in advance.

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  • Efficient (basic) regular expression implementation for streaming data

    - by Brendan Dolan-Gavitt
    I'm looking for an implementation of regular expression matching that operates on a stream of data -- i.e., it has an API that allows a user to pass in one character at a time and report when a match is found on the stream of characters seen so far. Only very basic (classic) regular expressions are needed, so a DFA/NFA based implementation seems like it would be well-suited to the problem. Based on the fact that it's possible to do regular expression matching using a DFA/NFA in a single linear sweep, it seems like a streaming implementation should be possible. Requirements: The library should try to wait until the full string has been read before performing the match. The data I have really is streaming; there is no way to know how much data will arrive, it's not possible to seek forward or backward. Implementing specific stream matching for a couple special cases is not an option, as I don't know in advance what patterns a user might want to look for. For the curious, my use case is the following: I have a system which intercepts memory writes inside a full system emulator, and I would like to have a way to identify memory writes that match a regular expression (e.g., one could use this to find the point in the system where a URL is written to memory). I have found (links de-linkified because I don't have enough reputation): stackoverflow.com/questions/1962220/apply-a-regex-on-stream stackoverflow.com/questions/716927/applying-a-regular-expression-to-a-java-i-o-stream www.codeguru.com/csharp/csharp/cs_data/searching/article.php/c14689/Building-a-Regular-Expression-Stream-Search-with-the-NET-Framework.htm But all of these attempt to convert the stream to a string first and then use a stock regular expression library. Another thought I had was to modify the RE2 library, but according to the author it is architected around the assumption that the entire string is in memory at the same time. If nothing's available, then I can start down the unhappy path of reinventing this wheel to fit my own needs, but I'd really rather not if I can avoid it. Any help would be greatly appreciated!

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  • LINQ to SQL: NOTing a prebuilt expression

    - by ck
    I'm building a library of functions for one of my core L2S classes, all of which return a bool to allow checking for certain situations. Example: Expression<Func<Account, bool>> IsSomethingX = a => a.AccountSupplementary != null && a.AccountSupplementary.SomethingXFlag != null && a.AccountSupplementary.SomethingXFlag.Value; Now to query where this is not true, I CAN'T do this: var myAccounts= context.Accounts .Where(!IsSomethingX); // does not compile However, using the syntax from the PredicateBuilder class, I've come up with this: public static IQueryable<T> WhereNot<T>(this IQueryable<T> items, Expression<Func<T, bool>> expr1) { var invokedExpr = Expression.Invoke(expr1, expr1.Parameters.Cast<Expression>()); return items.Where(Expression.Lambda<Func<T, bool>> (Expression.Not(invokedExpr), expr1.Parameters)); } var myAccounts= context.Accounts .WhereNot(IsSomethingX); // does compile which actually produces the correct SQL. Does this look like a good solution, and is there anything I need to be aware of that might cause me problems in future?

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