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• Introduction to WebCenter Personalization: &ldquo;The Conductor&rdquo;

  - by Steve Pepper

  There are some new faces in the town of WebCenter with the latest 11g PS3 release.  A new component has introduced itself as "Oracle WebCenter Personalization", a.k.a WCP, to simplify delivery of a personalized experience and content to end users.  This posting reviews one of the primary components within WCP: "The Conductor". The Conductor: This ain't just an ordinary cloud... One of the founding principals behind WebCenter Personalization was to provide an open client-side API that remains independent of the technology invoking it, in addition to independence from the architecture running it.  The Conductor delivers this, and much, much more. The Conductor is the engine behind WebCenter Personalization that allows flow-based documents, called "Scenarios", to be managed and executed on the server-side through a well published and RESTful api.      The Conductor also supports an extensible model for custom provider integration that can be easily invoked within a Scenario to promote seamless integration with existing business assets. Introducing the Scenario Conductor Scenarios are declarative offline-authored documents using the custom Personalization JDeveloper bundle included with WebCenter.  A Scenario contains one (or more) statements that can: Create variables that are scoped to the current execution context Iterate over collections, or loop until a specific condition is met Execute one or more statements when a condition is met Invoke other scenarios that exist within the same namespace Invoke a data provider that integrates with custom applications Once a variable is assigned within the Scenario's execution context, it can be referenced anywhere within the same Scenario using the common Expression Language syntax used in J2EE web containers. Scenarios are then published and tested to the Integrated WebLogic Server domain, or published remotely to other domains running WebCenter Personalization. Various Client-side Models The Conductor server API is built upon RESTful services that support a wide variety of clients able to communicate over HTTP.  The Conductor supports the following client-side models: REST:  Popular browser-based languages can be used to manage and execute Conductor Scenarios.  There are other public methods to retrieve configured provider metadata that can be used by custom applications. The Conductor currently supports XML and JSON for it's API syntax. Java: WebCenter Personalization delivers a robust and light-weight java client with the popular Jersey framework as it's foundation.  It has never been easier to write a remote java client to manage remote RESTful services. Expression Language (EL): Allow the results of Scenario execution to control your user interface or embed personalized content using the session-scoped managed bean.  The EL client can also be used in straight JSP pages with minimal configuration. Extensible Provider Framework The Conductor supports a pluggable provider framework for integrating custom code with Scenario execution.  There are two types of providers supported by the Conductor: Function Provider: Function Providers are simple java annotated classes with static methods that are meant to be served as utilities.  Some common uses would include: object creation or instantiation, data transformation, and the like.  Function Providers can be invoked using the common EL syntax from variable assignments, conditions, and loops. For example:  ${myUtilityClass:doStuff(arg1,arg2))} If you are familiar with EL Functions, Function Providers are based on the same concept. Data Provider: Like Function Providers, Data Providers are annotated java classes, but they must adhere to a much more strict object model.  Data Providers have access to a wealth of Conductor services, such as: Access to namespace-scoped configuration API that can be managed by Oracle Enterprise Manager, Scenario execution context for expression resolution, and more.  Oracle ships with three out-of-the-box data providers that supports integration with: Standardized Content Servers(CMIS),  Federated Profile Properties through the Properties Service, and WebCenter Activity Graph. Useful References If you are looking to immediately get started writing your own application using WebCenter Personalization Services, you will find the following references helpful in getting you on your way: Personalizing WebCenter Applications Authoring Personalized Scenarios in JDeveloper Using Personalization APIs Externally Implementing and Calling Function Providers Implementing and Calling Data Providers

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• Why is x=x++ undefined?

  - by ugoren

  It's undefined because the it modifies x twice between sequence points. The standard says it's undefined, therefore it's undefined. That much I know. But why? My understanding is that forbidding this allows compilers to optimize better. This could have made sense when C was invented, but now seems like a weak argument. If we were to reinvent C today, would we do it this way, or can it be done better? Or maybe there's a deeper problem, that makes it hard to define consistent rules for such expressions, so it's best to forbid them? So suppose we were to reinvent C today. I'd like to suggest simple rules for expressions such as x=x++, which seem to me to work better than the existing rules. I'd like to get your opinion on the suggested rules compared to the existing ones, or other suggestions. Suggested Rules: Between sequence points, order of evaluation is unspecified. Side effects take place immediately. There's no undefined behavior involved. Expressions evaluate to this value or that, but surely won't format your hard disk (strangely, I've never seen an implementation where x=x++ formats the hard disk). Example Expressions x=x++ - Well defined, doesn't change x. First, x is incremented (immediately when x++ is evaluated), then it's old value is stored in x. x++ + ++x - Increments x twice, evaluates to 2*x+2. Though either side may be evaluated first, the result is either x + (x+2) (left side first) or (x+1) + (x+1) (right side first). x = x + (x=3) - Unspecified, x set to either x+3 or 6. If the right side is evaluated first, it's x+3. It's also possible that x=3 is evaluated first, so it's 3+3. In either case, the x=3 assignment happens immediately when x=3 is evaluated, so the value stored is overwritten by the other assignment. x+=(x=3) - Well defined, sets x to 6. You could argue that this is just shorthand for the expression above. But I'd say that += must be executed after x=3, and not in two parts (read x, evaluate x=3, add and store new value). What's the Advantage? Some comments raised this good point. It's not that I'm after the pleasure of using x=x++ in my code. It's a strange and misleading expression. What I want is to be able to understand complicated expressions. Normally, a complicated expression is no more than the sum of its parts. If you understand the parts and the operators combining them, you can understand the whole. C's current behavior seems to deviate from this principle. One assignment plus another assignment suddenly doesn't make two assignments. Today, when I look at x=x++, I can't say what it does. With my suggested rules, I can, by simply examining its components and their relations.

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• Relation between [[Prototype]] and prototype in JavaScript

  - by Claudiu

  From http://www.jibbering.com/faq/faq_notes/closures.html : Note: ECMAScript defines an internal [[prototype]] property of the internal Object type. This property is not directly accessible with scripts, but it is the chain of objects referred to with the internal [[prototype]] property that is used in property accessor resolution; the object's prototype chain. A public prototype property exists to allow the assignment, definition and manipulation of prototypes in association with the internal [[prototype]] property. The details of the relationship between to two are described in ECMA 262 (3rd edition) and are beyond the scope of this discussion. What are the details of the relationship between the two? I've browsed through ECMA 262 and all I've read there is stuff like: The constructor’s associated prototype can be referenced by the program expression constructor.prototype, Native ECMAScript objects have an internal property called [[Prototype]]. The value of this property is either null or an object and is used for implementing inheritance. Every built-in function and every built-in constructor has the Function prototype object, which is the initial value of the expression Function.prototype Every built-in prototype object has the Object prototype object, which is the initial value of the expression Object.prototype (15.3.2.1), as the value of its internal [[Prototype]] property, except the Object prototype object itself. From this all I gather is that the [[Prototype]] property is equivalent to the prototype property for pretty much any object. Am I mistaken?

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• How can I access the group of a linq group-by query from a nested repeater control?

  - by Duke

  I'm using a linq group by query (with two grouping parameters) and would like to use the resulting data in a nested repeater. var dateGroups = from row in data.AsEnumerable() group row by new { StartDate = row["StartDate"], EndDate = row["EndDate"] }; "data" is a DataTable from an SqlDataAdapter-filled DataSet. "dateGroups" is used in the parent repeater, and I can access the group keys using Eval("key.StartDate") and Eval("key.EndDate"). Since dateGroups actually contains all the data rows grouped neatly by Start/End date, I'd like to access those rows to display the data in a child repeater. To what would I set the child repeater's DataSource? I have tried every expression in markup I could think of; I think the problem is that I'm trying to access an anonymous member (and I don't know how.) In case it doesn't turn out to be obvious, what would be the expression to access the elements in each iteration of the child repeater? Is there an expression that would let me set the DataSource in the markup, or will it have to be in the codebehind on some event in the parent repeater?

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• Good grammar for date data type for recursive descent parser LL(1)

  - by Totophil

  I'm building a custom expression parser and evaluator for production enviroment to provide a limited DSL to the users. The parser itself as the DSL, need to be simple. The parser is going to be built in an exotic language that doesn't support dynamic expression parsing nor has any parser generator tools available. My decision is to go for recursive descent approach with LL(1) grammar, so that even programmers with no previous experience in evaluating expression could quickly learn how the code works. It has to handle mixed expressions made up of several data types: decimals, percentages, strings and dates. And dates in the format of dd/mm/yyyy are easy to confuse with a string of devision ops. Is where a good solution to this problem? My own solution that is aimed at keeping the parser simple involves prefixing dates with a special symbol, let's say apostrophe: <date> ::= <apostr><digit><digit>/<digit><digit>/<digit><digit><digit><digit> <apostr> ::= ' <digit> ::= '0'..'9'

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• Why does division yield a vastly different result than multiplication by a fraction in floating points.

  - by Avram

  I understand why floating point numbers can't be compared, and know about the mantissa and exponent binary representation, but I'm no expert and today I came across something I don't get: Namely lets say you have something like: float denominator, numerator, resultone, resulttwo; resultone = numerator / denominator; float buff = 1 / denominator; resulttwo = numerator * buff; To my knowledge different flops can yield different results and this is not unusual. But in some edge cases these two results seem to be vastly different. To be more specific in my GLSL code calculating the Beckmann facet slope distribution for the Cook-Torrance lighitng model: float a = 1 / (facetSlopeRMS * facetSlopeRMS * pow(clampedCosHalfNormal, 4)); float b = clampedCosHalfNormal * clampedCosHalfNormal - 1.0; float c = facetSlopeRMS * facetSlopeRMS * clampedCosHalfNormal * clampedCosHalfNormal; facetSlopeDistribution = a * exp(b/c); yields very very different results to float a = (facetSlopeRMS * facetSlopeRMS * pow(clampedCosHalfNormal, 4)); facetDlopeDistribution = exp(b/c) / a; Why does it? The second form of the expression is problematic. If I say try to add the second form of the expression to a color I get blacks, even though the expression should always evaluate to a positive number. Am I getting an infinity? A NaN? if so why?

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• Programming R/Sweave for proper \Sexpr output

  - by deoksu

  Hi I'm having a bit of a problem programming R for Sweave, and the #rstats twitter group often points here, so I thought I'd put this question to the SO crowd. I'm an analyst- not a programmer- so go easy on me my first post. Here's the problem: I am drafting a survey report in Sweave with R and would like to report the marginal returns in line using \Sexpr{}. For example, rather than saying: Only 14% of respondents said 'X'. I want to write the report like this: Only \Sexpr{p.mean(variable)}$\%$ of respondents said 'X'. The problem is that Sweave() converts the results of the expression in \Sexpr{} to a character string, which means that the output from expression in R and the output that appears in my document are different. For example, above I use the function 'p.mean': p.mean<- function (x) {options(digits=1) mmm<-weighted.mean(x, weight=weight, na.rm=T) print(100*mmm) } In R, the output looks like this: p.mean(variable) >14 but when I use \Sexpr{p.mean(variable)}, I get an unrounded character string (in this case: 13.5857142857143) in my document. I have tried to limit the output of my function to 'digits=1' in the global environment, in the function itself, and and in various commands. It only seems to contain what R prints, not the character transformation that is the result of the expression and which eventually prints in the LaTeX file. as.character(p.mean(variable)) >[1] 14 >[1] "13.5857142857143" Does anyone know what I can do to limit the digits printed in the LaTeX file, either by reprogramming the R function or with a setting in Sweave or \Sexpr{}? I'd greatly appreciate any help you can give. Thanks, David

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• Regex For Finding Ctypes with Int32

  - by Stefan H

  (Hey all, I am looking for a little regex help... I am trying to find all CType(expression,Int32) s and replace them with CInt(expression) This, however, is proving quite difficult, considering there could be a nested Ctype(expression, Int32) within the regex match. Does anyone have any ideas for how to best go about doing this? Here is what I have now: Dim str As String = "CType((original.Width * CType((targetSize / CType(original.Height, Single)), Single)), Int32)" Dim exp As New Regex("CType\((.+), Int32\)") str = exp.Replace(str, "CInt($1)") But this will match the entire string and replace it. I was thinking of doing a recursive function to find the outer most match, and then work inwards, but that still presents a problem with things like CType(replaceChars(I), Int32)), Chr(CType(replacementChars(I), Int32) Any tips would be appreciated. Input returnString.Replace(Chr(CType(replaceChars(I), Int32)), Chr(CType(replacementChars(I), Int32))) Output: returnString.Replace(Chr(CInt(replaceChars(I))),Chr(CInt(replacementChars(I)))) Edit: Been working on it a little more and have a recursive function that I'm still working out the kinks in. Recursion + regex. it kinda hurts. Private Function FindReplaceCInts(ByVal strAs As String) As String System.Console.WriteLine(String.Format("Testing : {0}", strAs)) Dim exp As New Regex("CType\((.+), Int32\)") If exp.Match(strAs).Success Then For Each match As Match In exp.Matches(strAs) If exp.Match(match.Value.Substring(2)).Success Then Dim replaceT As String = match.Value.Substring(2) Dim Witht As String = FindReplaceCInts(match.Value.Substring(2)) System.Console.WriteLine(strAs.IndexOf(replaceT)) strAs.Replace(replaceT, Witht) End If Next strAs = exp.Replace(strAs, "CInt($1)") End If Return strAs End Function Cheers,

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• R + Bioconductor : combining probesets in an ExpressionSet

  - by Mike Dewar

  Hi, First off, this may be the wrong Forum for this question, as it's pretty darn R+Bioconductor specific. Here's what I have: library('GEOquery') GDS = getGEO('GDS785') cd4T = GDS2eSet(GDS) cd4T <- cd4T[!fData(cd4T)$symbol == "",] Now cd4T is an ExpressionSet object which wraps a big matrix with 19794 rows (probesets) and 15 columns (samples). The final line gets rid of all probesets that do not have corresponding gene symbols. Now the trouble is that most genes in this set are assigned to more than one probeset. You can see this by doing gene_symbols = factor(fData(cd4T)$Gene.symbol) length(gene_symbols)-length(levels(gene_symbols)) [1] 6897 So only 6897 of my 19794 probesets have unique probeset - gene mappings. I'd like to somehow combine the expression levels of each probeset associated with each gene. I don't care much about the actual probe id for each probe. I'd like very much to end up with an ExpressionSet containing the merged information as all of my downstream analysis is designed to work with this class. I think I can write some code that will do this by hand, and make a new expression set from scratch. However, I'm assuming this can't be a new problem and that code exists to do it, using a statistically sound method to combine the gene expression levels. I'm guessing there's a proper name for this also but my googles aren't showing up much of use. Can anyone help?

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• Powershell Regex help in extracting text between strings

  - by vivekeviv

  i Have an arguments like the one below which i pass to powershell script -arg1 -abc -def -arg2 -ghi -jkl -arg3 -123 -234 Now i need to extract three strings without any whitespace string 1: "-abc -def" string 2: "-ghi -jkl" string 3: "-123 -234" i figured this expression could do it. But this doesnt seem to work. $args -match '-arg1(?'arg1'.*?) -arg3(?'arg3'.*?) -arg3(?'arg3'.*)'. THis should return $matches['arg1'] etc. So whats wrong in above expression. Why do i get an error as shown below runScript.ps1 -arg1 -abc -def -arg2 -ghi -jkl -arg3 -123 -234 Unexpected token 'arg1'.?) -arg2 (?'arg2'.?) -arg3 (?'arg3'.)'' in expression or statement. At G:\powershell\tools\powershell\runTest.ps1:1 char:71 + $args -match '-arg1 (?'arg1'.?) -arg2 (?'arg2'.?) -arg3 (?'arg3'.)' <<<< + CategoryInfo : ParserError: (arg1'.?) -arg2...g3 (?'arg3'.)':String) [], ParseException + FullyQualifiedErrorId : UnexpectedToken and also the second question is how do i make arg1 or arg2 or arg3 optional? The argument to script can be -arg2 -def -ghi. I'll take some default values for arg(1|2|3) that is not mentioned. Thanks

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• compareTo and nested Enums

  - by echox

  Hi, in "A Programmers Guide to Java SCJP Certification" I found an example which I can't follow. This the given enum: enum Scale3 { GOOD(Grade.C), BETTER(Grade.B), BEST(Grade.A); enum Grade {A, B, C} private Grade grade; Scale3(Grade grade) { this.grade = grade; } public Grade getGrade() { return grade; } } This is the given expression: Scale3.GOOD.getGrade().compareTo(Scale3.Grade.A) > 0; I don't understand why this expression will be true? The return value will be 2. compareTo() will return a value 0 if the given object is "less" than the object. Scale3.Grade.A is the "biggest" element of Grades, its ordinal number is 0. Scale3.GOOD is the "biggest" element of Scale3, its ordinal number is also 0. The constructor of Scale3 is called with Scale3.Grade.C, which ordinal number is 2. So the given expression is equal to the following code: Scale3.Grade.C.compareTo(Scale3.Grade.A) > 0; A is "bigger" than C, so shouldn't be the result < 0?

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• RegularExpression-esque search matching Objects in List

  - by Pindatjuh

  I'm currently working on an implementation of the following idea, and I was wondering if there is any literature on this subject. Working with Java, but the principle applies on any language with a decent type-system, I like to implement: matching Objects from a List using a RegularExpression-esque search: So let's say I have a List containing List<Object> x = new ArrayList<Object>(); x.add(new Object()); x.add("Hello World"); x.add("Second String"); x.add(5); // Integer (auto-boxing) x.add(6); // Integer Then I create a "Regular Expression" (not working with a stream of characters, but working with a stream of Objects), and instead of character-classes, I use type-system properties: [String][Integer] And this would match one sublist: {Match["Second String", 5]}. The expression: [String:length()<15] Will match two sublist (each of length 1) containing a String which instance is passing the expression instance.length() < 5: {Match["Hello World"],Match["Second String"]}. [Object][Object] Matches any pair in the List: {Match[Object,"Hello World"],Match["Second String", 5]}, in a streamed manner (no overlapping matches). Ofcourse, my implementation will have grouping, lookahead/lookbehinds and is hierarchical (i.e. matching n elements from Lists in Lists), etc. The above merely illustrates the concept. Is there a name for this principle, and is there literature available on it?

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• Recognizing terminals in a CFG production previously not defined as tokens.

  - by kmels

  I'm making a generator of LL(1) parsers, my input is a CoCo/R language specification. I've already got a Scanner generator for that input. Suppose I've got the following specification: COMPILER 1. CHARACTERS digit="0123456789". TOKENS number = digit{digit}. decnumber = digit{digit}"."digit{digit}. PRODUCTIONS Expression = Term{"+"Term|"-"Term}. Term = Factor{"*"Factor|"/"Factor}. Factor = ["-"](Number|"("Expression")"). Number = (number|decnumber). END 1. So, if the parser generated by this grammar receives a word "1+1", it'd be accepted i.e. a parse tree would be found. My question is, the character "+" was never defined in a token, but it appears in the non-terminal "Expression". How should my generated Scanner recognize it? It would not recognize it as a token. Is this a valid input then? Should I add this terminal in TOKENS and then consider an error routine for a Scanner for it to skip it? How does usual language specifications handle this?

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• Suggestions for a Cron like scheduler in Python?

  - by jamesh

  I'm looking for a library in Python which will provide at and cron like functionality. I'd quite like have a pure Python solution, rather than relying on tools installed on the box; this way I run on machines with no cron. For those unfamiliar with cron: you can schedule tasks based upon an expression like: 0 2 * * 7 /usr/bin/run-backup # run the backups at 0200 on Every Sunday 0 9-17/2 * * 1-5 /usr/bin/purge-temps # run the purge temps command, every 2 hours between 9am and 5pm on Mondays to Fridays. The cron time expression syntax is less important, but I would like to have something with this sort of flexibility. If there isn't something that does this for me out-the-box, any suggestions for the building blocks to make something like this would be gratefully received. Edit I'm not interested in launching processes, just "jobs" also written in Python - python functions. By necessity I think this would be a different thread, but not in a different process. To this end, I'm looking for the expressivity of the cron time expression, but in Python. Cron has been around for years, but I'm trying to be as portable as possible. I cannot rely on its presence.

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• I need to speed up a function. Should I use cython, ctypes, or something else?

  - by Peter Stewart

  I'm having a lot of fun learning Python by writing a genetic programming type of application. I've had some great advice from Torsten Marek, Paul Hankin and Alex Martelli on this site. The program has 4 main functions: generate (randomly) an expression tree. evaluate the fitness of the tree crossbreed mutate As all of generate, crossbreed and mutate call 'evaluate the fitness'. it is the busiest function and is the primary bottleneck speedwise. As is the nature of genetic algorithms, it has to search an immense solution space so the faster the better. I want to speed up each of these functions. I'll start with the fitness evaluator. My question is what is the best way to do this. I've been looking into cython, ctypes and 'linking and embedding'. They are all new to me and quite beyond me at the moment but I look forward to learning one and eventually all of them. The 'fitness function' needs to compare the value of the expression tree to the value of the target expression. So it will consist of a postfix evaluator which will read the tree in a postfix order. I have all the code in python. I need advice on which I should learn and use now: cython, ctypes or linking and embedding. Thank you.

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• EF Many-to-many dbset.Include in DAL on GenericRepository

  - by Bryant

  I can't get the QueryObjectGraph to add INCLUDE child tables if my life depended on it...what am I missing? Stuck for third day on something that should be simple :-/ DAL: public abstract class RepositoryBase<T> where T : class { private MyLPL2Context dataContext; private readonly IDbSet<T> dbset; protected RepositoryBase(IDatabaseFactory databaseFactory) { DatabaseFactory = databaseFactory; dbset = DataContext.Set<T>(); DataContext.Configuration.LazyLoadingEnabled = true; } protected IDatabaseFactory DatabaseFactory { get; private set; } protected MyLPL2Context DataContext { get { return dataContext ?? (dataContext = DatabaseFactory.Get()); } } public IQueryable<T> QueryObjectGraph(Expression<Func<T, bool>> filter, params string[] children) { foreach (var child in children) { dbset.Include(child); } return dbset.Where(filter); } ... DAL repositories public interface IBreed_TranslatedSqlRepository : ISqlRepository<Breed_Translated> { } public class Breed_TranslatedSqlRepository : RepositoryBase<Breed_Translated>, IBreed_TranslatedSqlRepository { public Breed_TranslatedSqlRepository(IDatabaseFactory databaseFactory) : base(databaseFactory) {} } BLL Repo: public IQueryable<Breed_Translated> QueryObjectGraph(Expression<Func<Breed_Translated, bool>> filter, params string[] children) { return _r.QueryObjectGraph(filter, children); } Controller: var breeds1 = _breedTranslatedRepository .QueryObjectGraph(b => b.Culture == culture, new string[] { "AnimalType_Breed" }) .ToList(); I can't get to Breed.AnimalType_Breed.AnimalTypeId ..I can drill as far as Breed.AnimalType_Breed then the intelisense expects an expression? Cues if any, DB Tables: bold is many-to-many Breed, Breed_Translated, AnimalType_Breed, AnimalType, ...

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• c# syntax and Linq, IQueryable

  - by hdiver

  Hello. This is a question about the SYNTAX of c# and NOT about how we call/use IQueryable Can someone please explain to me: We have this declaration (System.Linq): public static double Average<TSource>(this IQueryable<TSource> source, Expression<Func<TSource, int>> selector) and to call the Average double average = fruits.AsQueryable().Average(s => s.Length); I understand how to call the Average and all the similar static method of IQueryable but I don’t understand the syntax of the declaration. public static double Average<TSource>(this IQueryable<TSource> source, Expression<Func<TSource, int>> selector) What does the <TSource> mean in Average<TSource>( and also the this IQueryable<TSource> source. since only one parameter passes when we call it and the actual lamda expression (s => s.Length); Thanks in advance.

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• Does "epsilon" really guarantees anything in floating-point computations?!

  - by Michal Czardybon

  To make the problem short let's say I want to compute expression: a / (b - c) on float's. To make sure the result is meaningful, I can check if 'b' and 'c' are inequal: float eps = std::numeric_limits<float>::epsilon(); if ((b - c) > EPS || (c - b) > EPS) { return a / (b - c); } but my tests show it is not enough to guarantee either meaningful results nor not failing to provide a result if it is possible. Case 1: a = 1.0f; b = 0.00000003f; c = 0.00000002f; Result: The if condition is NOT met, but the expression would produce a correct result 100000008 (as for the floats' precision). Case 2: a = 1e33f; b = 0.000003; c = 0.000002; Result: The if condition is met, but the expression produces not a meaningful result +1.#INF00. I found it much more reliable to check the result, not the arguments: const float INF = numeric_limits<float>::infinity(); float x = a / (b - c); if (-INF < x && x < INF) { return x; } But what for is the epsilon then and why is everyone saying epsilon is good to use?

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• Compiling a Windows C++ program in g++

  - by Phenom

  I'm trying to compile a Windows C++ program in g++. This is what I get. /usr/include/c++/4.4/backward/backward_warning.h:28:2: warning: #warning This file includes at least one deprecated or antiquated header which may be removed without further notice at a future date. Please use a non-deprecated interface with equivalent functionality instead. For a listing of replacement headers and interfaces, consult the file backward_warning.h. To disable this warning use -Wno-deprecated. btree.cpp:1204: error: ‘_TCHAR’ has not been declared btree.cpp: In function ‘int _tmain(int, int**)’: btree.cpp:1218: error: ‘__int64’ was not declared in this scope btree.cpp:1218: error: expected ‘;’ before ‘frequency’ btree.cpp:1220: error: ‘LARGE_INTEGER’ was not declared in this scope btree.cpp:1220: error: expected primary-expression before ‘)’ token btree.cpp:1220: error: ‘frequency’ was not declared in this scope btree.cpp:1220: error: ‘QueryPerformanceFrequency’ was not declared in this scope btree.cpp:1262: error: expected primary-expression before ‘)’ token btree.cpp:1262: error: ‘start’ was not declared in this scope btree.cpp:1262: error: ‘QueryPerformanceCounter’ was not declared in this scope btree.cpp:1264: error: name lookup of ‘i’ changed for ISO ‘for’ scoping btree.cpp:1264: note: (if you use ‘-fpermissive’ G++ will accept your code) btree.cpp:1304: error: expected primary-expression before ‘)’ token btree.cpp:1304: error: ‘end’ was not declared in this scope btree.cpp:1306: error: ‘total’ was not declared in this scope btree.cpp:1316: error: ‘getchar’ was not declared in this scope The first thing I noticed is that there are these variable types called _TCHAR, _int64, and LARGE_INTEGER, which is probably a Windows thing. What can these be changed to so that they will work in g++? Also, if there's anything else in here that you know can be converted to g++, that would be helpful. I got the code from here: http://touc.org/btree.html

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• Can we have a component-scoped bean in a JSF2 composite component?

  - by Pradyumna

  Hi, I was wondering how I could create "component-scoped" beans, or so-to-say, "local variables inside a composite component" that are private to the instance of the composite component, and live as long as that instance lives. Below are more details, explained with an example: Suppose there is a "calculator" component - something that allows users to type in a mathematical expression, and evaluates its value. Optionally, it also plots the associated function. I can make a composite component that has: a text box for accepting the math expression two buttons called "Evaluate", and "Plot" another nested component that plots the function It is evidently a self-contained piece of function; so that somebody who wants to use it may just say <math:expressionEvaluator /> But obviously, the implementation would need a java object - something that evaluates the expression, something that computes the plot points, etc. - and I imagine it can be a bean - scoped just for this instance of this component, not a view-scoped or request-scoped bean that is shared across all instances of the component. How do I create such a bean? Is that even possible with composite components?

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• JavaScript: why `null == 0` is false?

  - by lemonedo

  I had to write a routine that increments the value of a variable by 1 if it is a number, or assigns 0 to the variable if it is not a number. The variable can be incremented by the expression, or be assigned null. No other write access to the variable is allowed. So, the variable can be in three states: it is 0, a positive integer, or null. My first implementation was: v >= 0 ? v += 1 : v = 0 (Yes, I admit that v === null ? v = 0 : v += 1 is the exact solution, but I wanted to be concise then.) It failed since null >= 0 is true. I was confused, since if a value is not a number, an numeric expression involving it must be false always. Then I found that null is like 0, since null + 1 == 1, 1 / null == Infinity, Math.pow(2.718281828, null) == 1, ... Strangely enough, however, null == 0 is evaluated to false. I guess null is the only value that makes the following expression false: (v == 0) === (v >= 0 && v <= 0) So why null is so special in JavaScript?

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• XPath and XML: Multiple namespaces

  - by emragins

  So I have a document that looks like <a xmlns="uri1" xmlns:pre2="uri2"> <b xmlns:pre3="uri3"> <pre3:c> <stuff></stuff> <goes></goes> <here></here> </pre3:c> <pre3:d xmlns="uri4"> <under></under> <the></the> <tree></tree> </pre3:d> </b> </a> I want an xpath expression that will get me <under>. This has a namespaceURI of uri4. Right now my expression looks like: //ns:a/ns:b/pre3:d/pre4:under I have the namespace manager add 'ns' for the default namespace (uri1 in this case) and I have it defined with pre2, pre3, and pre4 for uri2, uri3, and uri4 respectively. I get the error "Expression must evaluate to a node-set." I know that the node exists. I know that everything up until the pre4:under in my xpath works fine as I use it in the rest of the document with no issues. It's the additional pre4:under that causes the error, and I'm not sure why. Any ideas? Thanks.

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• Using DisplayFor inside a display template

  - by Oenotria

  I've created a htmlhelper extension to reduce the amount of repetitive markup when creating forms: public static MvcHtmlString RenderField<TModel, TValue>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TValue>> expression) { return htmlHelper.DisplayFor(expression, "formfield"); } The idea being that inside my views I can just write @Html.RenderField(x=>x.MyFieldName) and it will print the label and the field's content with the appropriate div tags in place already. Inside the displaytemplates folder I have created formfield.cshtml containing the following: <div class="display-group"> <div class="display-label"> @Html.LabelFor(x => x) </div> <div class="display-field"> @Html.DisplayFor(x => x) </div> </div> Unfortunately it doesn't appear that it is possible to nest DisplayFor inside a display template (it doesn't render anything). I don't want to just using @Model because then I won't get checkboxes for boolean values, calendar controls for dates etc. Is there a good way around this?

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• Checked and Unchecked operators don't seem to be working when...

  - by flockofcode

  1) Is UNCHECKED operator in effect only when expression inside UNCHECKED context uses an explicit cast ( such as byte b1=unchecked((byte)2000); ) and when conversion to particular type can happen implicitly? I’m assuming this since the following expression throws a compile time error: byte b1=unchecked(2000); //compile time error 2) a) Do CHECKED and UNCHECKED operators work only when resulting value of an expression or conversion is of an integer type? I’m assuming this since in the first example ( where double type is being converted to integer type ) CHECKED operator works as expected: double m = double.MaxValue; b=checked((byte)m); // reports an exception , while in second example ( where double type is being converted to a float type ) CHECKED operator doesn’t seem to be working. since it doesn't throw an exception: double m = double.MaxValue; float f = checked((float)m); // no exception thrown b) Why don’t the two operators also work with expressions where type of a resulting value is of floating-point type? 2) Next quote is from Microsoft’s site: The unchecked keyword is used to control the overflow-checking context for integral-type arithmetic operations and conversions I’m not sure I understand what exactly have expressions and conversions such as unchecked((byte)(100+200)); in common with integrals? Thank you

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• Nested bind expressions

  - by user328543

  This is a followup question to my previous question. #include <functional> int foo(void) {return 2;} class bar { public: int operator() (void) {return 3;}; int something(int a) {return a;}; }; template <class C> auto func(C&& c) -> decltype(c()) { return c(); } template <class C> int doit(C&& c) { return c();} template <class C> void func_wrapper(C&& c) { func( std::bind(doit<C>, std::forward<C>(c)) ); } int main(int argc, char* argv[]) { // call with a function pointer func(foo); func_wrapper(foo); // error // call with a member function bar b; func(b); func_wrapper(b); // call with a bind expression func(std::bind(&bar::something, b, 42)); func_wrapper(std::bind(&bar::something, b, 42)); // error // call with a lambda expression func( [](void)->int {return 42;} ); func_wrapper( [](void)->int {return 42;} ); return 0; } I'm getting a compile errors deep in the C++ headers: functional:1137: error: invalid initialization of reference of type ‘int (&)()’ from expression of type ‘int (*)()’ functional:1137: error: conversion from ‘int’ to non-scalar type ‘std::_Bind(bar, int)’ requested func_wrapper(foo) is supposed to execute func(doit(foo)). In the real code it packages the function for a thread to execute. func would the function executed by the other thread, doit sits in between to check for unhandled exceptions and to clean up. But the additional bind in func_wrapper messes things up...

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