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  • Binding to element in WPF: can the Path expression do math?

    - by John
    Hi I'm trying to bind a control to the parent's Height/width property using ElementName and a Path. However, I don't want to bind to the actual height, but to exactly half the height. Can the Path expression do the math? e.g. Path={ActualHeight/2} I couldn't find a way to do that. IS there any other clever approach? Thanks!

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  • How to use Regular Expression to extract information from a HTML webpage?

    - by user569248
    How to use Regular Expression to extract the answer "Here is the answer" from a HTML webpage like this? <b>Last Question:</b> <b>Here is the answer</b> ..:: Update ::.. Thanks everybody! Here is my solution by using BeautifulSoup since I'm using Python framework: response = opener.open(url) the_page = response.read() soup = BeautifulSoup(''.join(the_page)) paraText1 = soup.body.find('div', 'div_id', text = u'Last Question:') if paraText1: answer = paraText1.next

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  • How To? Use an Expression Tree to call a Generic Method when the Type is only known at runtime.

    - by David Williams
    Please bear with me; I am very new to expression trees and lambda expressions, but trying to learn. This is something that I solved using reflection, but would like to see how to do it using expression trees. I have a generic function: private void DoSomeThing<T>( param object[] args ) { // Some work is done here. } that I need to call from else where in my class. Now, normally, this would be be simple: DoSomeThing<int>( blah ); but only if I know, at design time that I am working with an int. When I do not know the type until runtime is where I need the help. Like I said, I know how to do it via reflection, but I would like to do it via expression trees, as my (very limited) understanding is that I can do so. Any suggestions or points to sites where I can get this understanding, preferably with sample code?

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  • How to create a dynamic Linq Join extension method

    - by Royd Brayshay
    There was a library of dynamic Linq extensions methods released as a sample with VS2008. I'd like to extend it with a Join method. The code below fails with a parameter miss match exception at run time. Can anyone find the problem? public static IQueryable Join(this IQueryable outer, IEnumerable inner, string outerSelector, string innerSelector, string resultsSelector, params object[] values) { if (inner == null) throw new ArgumentNullException("inner"); if (outerSelector == null) throw new ArgumentNullException("outerSelector"); if (innerSelector == null) throw new ArgumentNullException("innerSelector"); if (resultsSelector == null) throw new ArgumentNullException("resultsSelctor"); LambdaExpression outerSelectorLambda = DynamicExpression.ParseLambda(outer.ElementType, null, outerSelector, values); LambdaExpression innerSelectorLambda = DynamicExpression.ParseLambda(inner.AsQueryable().ElementType, null, innerSelector, values); ParameterExpression[] parameters = new ParameterExpression[] { Expression.Parameter(outer.ElementType, "outer"), Expression.Parameter(inner.AsQueryable().ElementType, "inner") }; LambdaExpression resultsSelectorLambda = DynamicExpression.ParseLambda(parameters, null, resultsSelector, values); return outer.Provider.CreateQuery( Expression.Call( typeof(Queryable), "Join", new Type[] { outer.ElementType, inner.AsQueryable().ElementType, outerSelectorLambda.Body.Type, innerSelectorLambda.Body.Type, resultsSelectorLambda.Body.Type }, outer.Expression, inner.AsQueryable().Expression, Expression.Quote(outerSelectorLambda), Expression.Quote(innerSelectorLambda), Expression.Quote(resultsSelectorLambda))); } I've now fixed it myself, here's the answer. Please vote it up or add a better one.

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  • Compilation error while compiling an existing code base

    - by brijesh
    Hi, While building an existing code base on Mac OS using its native build setup I am getting some basic strange error while compilation phase. /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/bits/locale_facets.h: In constructor 'std::collate_byname<_CharT::collate_byname(const char*, size_t)': /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/bits/locale_facets.h:1072: error: '_M_c_locale_collate' was not declared in this scope /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/ppc-darwin/bits/messages_members.h: In constructor 'std::messages_byname<_CharT::messages_byname(const char*, size_t)': /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/ppc-darwin/bits/messages_members.h:79: error: '_M_c_locale_messages' was not declared in this scope /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits: At global scope: /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:897: error: 'float __builtin_huge_valf()' cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:897: error: a function call cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:897: error: 'float __builtin_huge_valf()' cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:897: error: a function call cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:899: error: 'float __builtin_nanf(const char*)' cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:899: error: a function call cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:899: error: 'float __builtin_nanf(const char*)' cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:899: error: a function call cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:900: error: field initializer is not constant /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:915: error: field initializer is not constant

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  • Passing in a lambda to a Where statement

    - by sonicblis
    I noticed today that if I do this: var items = context.items.Where(i => i.Property < 2); items = items.Where(i => i.Property > 4); Once I access the items var, it executes only the first line as the data call and then does the second call in memory. However, if I do this: var items = context.items.Where(i => i.Property < 2).Where(i => i.Property > 4); I get only one expression executed against the context that includes both where statements. I have a host of variables that I want to use to build the expression for the linq lambda, but their presence or absence changes the expression such that I'd have to have a rediculous number of conditionals to satisfy all cases. I thought I could just add the Where() statements as in my first example above, but that doesn't end up in a single expression that contains all of the criteria. Therefore, I'm trying to create just the lambda itself as such: //bogus syntax if (var1 == "something") var expression = Expression<Func<item, bool>>(i => i.Property == "Something); if (var2 == "somethingElse") expression = expression.Where(i => i.Property2 == "SomethingElse"); And then pass that in to the where of my context.Items to evaluate. A) is this right, and B) if so, how do you do it?

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  • Creating a sort function for a generic list

    - by Andrey
    I have a method for sorting generic lists by the object fields: public static IQueryable<T> SortTable<T>(IQueryable<T> q, string sortfield, bool ascending) { var p = Expression.Parameter(typeof(T), "p"); if (typeof(T).GetProperty(sortfield).PropertyType == typeof(int?)) { var x = Expression.Lambda<Func<T, int?>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } else if (typeof(T).GetProperty(sortfield).PropertyType == typeof(int)) { var x = Expression.Lambda<Func<T, int>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } else if (typeof(T).GetProperty(sortfield).PropertyType == typeof(DateTime)) { var x = Expression.Lambda<Func<T, DateTime>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } // many more for every type return q; } Is there any way I can collapse those ifs to a single generic statement? The main problem is that for the part Expression.Lambda<Func<T, int>> I am not sure how to write it generically.

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  • What language is to binary, as Perl is to text?

    - by ehdr
    I am looking for a scripting (or higher level programming) language (or e.g. modules for Python or similar languages) for effortlessly analyzing and manipulating binary data in files (e.g. core dumps), much like Perl allows manipulating text files very smoothly. Things I want to do include presenting arbitrary chunks of the data in various forms (binary, decimal, hex), convert data from one endianess to another, etc. That is, things you normally would use C or assembly for, but I'm looking for a language which allows for writing tiny pieces of code for highly specific, one-time purposes very quickly. Any suggestions?

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  • What programming language best bridges the gap between pseudocode and code?

    - by Kai
    As I write code from now on, I plan to first lay out everything in beautiful, readable pseudocode and then implement the program around that structure. If I rank the languages that I currently know from easiest to most difficult to translate, I'd say: Lisp, Python, Lua, C++, Java, C I know that each language has its strength and weaknesses but I'm focusing specifically on pseudocode. What language do you use that is best suited for pseudocode-to-code? I always enjoy picking up new languages. Also, if you currently use this technique, I'd love to hear any tips you have about structuring practical pseudocode. Note: I feel this is subjective but has a clear answer per individual preference. I'm asking this here because the SO community has a very wide audience and is likely to suggest languages and techniques that I would otherwise not encounter.

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  • What emoticons can you put into class names in your language?

    - by Chris Gill
    I've just had a "discussion" with a developer about naming classes in C#. My final throw away line was, "Let's not put any emoticons in our class names." I can't think of a way you could put emoticons in C# class names, but I haven't thought too hard about it. Is this possible? Does any programming language allow it? What would be the best/worst language to be able to perform this in? Update: The Scheme answer bests answers my question. It was a quick idea after a quick discussion so I'm going to accept after a short amount of time and then move on with my life. Thanks for the responses.

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  • Are there any issues with MySQL's i18n(indic language) support ?

    - by anjanb
    Hi All, We're evaluating MySQL and PostgreSQL for building our indic language web application which will use MySQL or PostgreSQL. One of my colleagues mentioned that MySQL had issues with i18n. I mostly come from the Oracle world and although I've played a lil with MySQL, I don't know enough to know that there are issues with its i18n support. Does anyone know issues with MySQL's i18n support and if PostgreSQL would be better placed for building an application with indic language support(kannada, telugu, tamil, etc) ? Just so you know, we're going to be using J2EE to build this application and we will be using JDBC drivers to access the DB. P.S : Will anything change if we were to use Rails to build the app instead of J2EE ? Thank you,

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