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  • Right rotate of tree in Haskell: how is it work?

    - by Roman
    I don't know haskell syntax, but I know some FP concepts (like algebraic data types, pattern matching, higher-order functions ect). Can someone explain please, what does this code mean: data Tree ? = Leaf ? | Fork ? (Tree ?) (Tree ?) rotateR tree = case tree of Fork q (Fork p a b) c -> Fork p a (Fork q b c) As I understand, first line is something like Tree-type declaration (but I don't understand it exactly). Second line includes pattern matching (I don't understand as well why do we need to use pattern matching here). And third line does something absolutely unreadable for non-haskell developer. I've found definition of Fork as fork (f,g) x = (f x, g x) but I can't move further anymore.

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  • Getters and Setters: Code smell, Necessary Evil, or Can't Live Without Them [closed]

    - by Avery Payne
    Possible Duplicate: Allen Holub wrote “You should never use get/set functions”, is he correct? Is there a good, no, a very good reason, to go through all the trouble of using getters and setters for object-oriented languages? What's wrong with just using a direct reference to a property or method? Is there some kind of "semantical coverup" that people don't want to talk about in polite company? Was I just too tired and fell asleep when someone walked out and said "Thou Shalt Write Copious Amounts of Code to Obtain Getters and Setters"? Follow-up after a year: It seems to be a common occurrence with Java, less so with Python. I'm beginning to wonder if this is more of a cultural phenomena (related to the limitations of the language) rather than "sage advice". The -1 question score is complete for-the-lulz as far as I am concerned. It's interesting that there are specific questions that are downvoted, not because they are "bad questions", but rather, because they hit someone's raw nerve.

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  • Can I make valgrind ignore glibc libraries?

    - by Jack
    Is it possible to tell valgrind to ignore some set of libraries? Specifically glibc libraries.. Actual Problem: I have some code that runs fine in normal execution. No leaks etc. When I try to run it through valgrind, I get core dumps and program restarts/stops. Core usually points to glibc functions (usually fseek, mutex etc). I understand that there might be some issue with incompatible glibc / valgrind version. I tried various valgrind releases and glibc versions but no luck. Any suggestions?

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  • Webservice and ORM Framework?

    - by Sebastian
    Does anybody know a good web framework that includes an ORM mapper and allows straight forward implementation of web services? I'm looking for a framework written in PHP or C++. I'm looking for the following features (not all of them required, some will do nicely) data definition in one place used by database and web service WSDL generation XML output/JSON output boilerplate code generation So what I would like is a framework that let's me specify the objects, the web service functions on those objects and then generate everything that is required leaving me to fill the business logic (connecting the database to the web service). Anything like that out there? Background information for why I need this: I'm looking into creating a web project: the client is a rich web application that fetches all its data using AJAX. It will be completely custom made using only a low level javascript library. The server back end is supposed to serve static content and javascript (basically the rich web application) and to provide a RESTful web service API (which I would like to implement using aforementioned framework).

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  • two HashMap iteration

    - by user431276
    I have two HashMaps and I can iterate both hashmaps with following code Iterator it = mp.entrySet().iterator(); while (it.hasNext()) { Map.Entry pairs = (Map.Entry)it.next(); String firstVal = pairs.getValue(); } Iterator it2 = mp2.entrySet().iterator(); while (it2.hasNext()) { Map.Entry pairs2 = (Map.Entry)it.next(); String SecondVal = pairs2.getValue(); } myFunction(firstVal, SecondVal) Is there anyway to iterate two hashmaps at the same time without using two loops? Currently, I have a method that accepts two parameters and each parameter value is stored in first and second hashmap. I have to iterate first hash then second to get values. I think there must be a good way to do it but I don't know :( P.S: there could be some errors in above code as this is just an example to explain my problem. Each iterator is a method in original program and accept one parameter. I couldn't copy past real time functions as they are HUGE !

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  • How to implement square root and exponentiation on arbitrary length numbers?

    - by tomp
    I'm working on new data type for arbitrary length numbers (only non-negative integers) and I got stuck at implementing square root and exponentiation functions (only for natural exponents). Please help. I store the arbitrary length number as a string, so all operations are made char by char. Please don't include advices to use different (existing) library or other way to store the number than string. It's meant to be a programming exercise, not a real-world application, so optimization and performance are not so necessary. If you include code in your answer, I would prefer it to be in either pseudo-code or in C++. The important thing is the algorithm, not the implementation itself. Thanks for the help.

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  • use MACRO __FUNCTION__ with inline function

    - by Kurzack
    Hi all, I want to add debug message in kmalloc function in linux kernel. So my goal is to print all functions that call kmalloc. I tried to add printk("caller : %s size : %d",FUNCTION, size); in kmalloc function in slab.h but, the result of FUNCTION is kmalloc itself. I realised that MACRO is processed first before inline function (fyi, kmalloc is an inline function). Now, my question is, what is the simplest way to add debug message to kmalloc? Thanks in advance guys.

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  • Issues rendering image in flash via Context.Response.Write C# asp.

    - by Justin
    I am having an issue rendering images in flash via a character array. I am sending it from a webhandler via Context.Response.Write as a Base64CharacterArray. It functions 100% properly in a windows environment, however when using a Mac the image data is not retrieved correctly causing the image to appear incorrectly. It does not affect the data,however as it is rendered properly in a player which accesses the data via a webservice. I am at the end of my rope on this one. Anything will help. You can find an example at the following url http://www.discoverirelandtoday.com/photoalbum/Public/Main.aspx Thanks

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  • is PHP itself transforming into a framework?

    - by Elzo Valugi
    At the beginning PHP was a scripting language. But after the introduction and improvement of OOP I see more and more objects added to the core. They started with SPL which grew a lot, now we have DOMDocument family, DateTime family which should be part of PECL, Pear or Zend Framework or implemented by each one of us. Shouldn't be php only for build-in functions and all these objects passed to something else? Example. DateTime class is part of the core and I see it very similar with Zend_Date.

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  • How do I write a scheme macro that defines a variable and also gets the name of that variable as a s

    - by Jason Baker
    This is mostly a follow-up to this question. I decided to just keep YAGNI in mind and created a global variable (libpython). I set it to #f initially, then set! it when init is called. I added a function that should handle checking if that value has been initialized: (define (get-cpyfunc name type) (lambda args (if libpython (apply (get-ffi-obj name libpython type) args) (error "Call init before using any Python C functions")))) So now here's what I want to do. I want to define a macro that will take the following: (define-cpyfunc Py_Initialize (_fun -> _void)) And convert it into this: (define Py_Initialize (get-cpyfunc "Py_Initialize" (_fun -> _void))) I've been reading through the macro documentation to try figuring this out, but I can't seem to figure out a way to make it work. Can anyone help me with this (or at least give me a general idea of what the macro would look like)? Or is there a way to do this without macros?

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  • Install driver by using C++

    - by user296359
    Hi, This is a question about installing driver. I have the following files : aaa.cat aaa.inf x86\ttt.sys I can install this driver by clicking "update driver" in device manager. But now I need to install this driver on Windows (XP, Vista and Win7) by using C++. How could I do this? On the other hand, I can't use install shield or other tool to do the job. That is why I am asking this question. Thanks in advance. I have found this page, which mentioned SetupInstallFile and SetupInstallFileEx functions. Is this the answer? http://msdn.microsoft.com/en-us/library/aa376958%28VS.85%29.aspx

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  • MS Access "#Name?" in unbound field on SOME machines

    - by alkorya
    I have a datasheet form bound to table. I added 2 unbound fields and set their Control Source properties to user defined VBA functions: 1. ConcatRelated (http://allenbrowne.com/func-concat.html) 2. Custom function that returns a string: Public Function GetLowestSatatus(LookupField As String, JSAID As Integer) As String On Error Resume Next GetLowestSatatus = DLookup(LookupField, "JsaStatuses", "ID=" & DMin("StatusID", "Tasks", "JSAID =" & JSAID)) End Function It works fine on my and some other machines but there are machines I got "#Name?" in these 2 unbound fields. All machines configured identically. Any ideas? Thank you!

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  • Autorelease for CGMutablePathRef?

    - by huggie
    Hi, I am developing for iphone. I want to creating a mutable path via CGPathCreateMutable(), and I want to return it out of the function which creates it. I'm suppose to call a CGPathRelease() when I'm done with it. But since I'm returning it I wish to autorelease it. Since Quartz path is a C code (and doesn't look like an objective C object), is it correct that I cannot call autorelease on it? Edit: For others who stumble upon this question, the below advise is for C functions returning Core foundation objects only. For objective C methods returning Core foundation objects, see http://stackoverflow.com/questions/2901942/ownership-regarding-to-returned-quartz-objects

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  • Convert wide to long format in R

    - by Anthony
    My data has a long format similar to the one below: ID Language MotherTongue SpokenatHome HomeLang 1 English English English 1 French French 1 Polish Polish 2 Lebanese Lebanese Lebanese Labanese 2 Arabic Arabbic Here is the output I am looking for: ID Language1 Language2 Language 3 MotherTongue1 MotherTongue2 SpokenatHome1 HomeLan 1 English French Polish English Polish French English 2 Lebanese Arabic Labanese Arabic I'm using using the melt and dcast functions of the reshape2 package, but it does not work. Does anyone know how to do this? Thanks. df<-df[,c("OEN", "Langugae","MotherTongue", "SpokenatHome", "MainHomeLanguage")] dfl <- melt(df, id.vars=c("OEN", "Langugae"), measure.vars=c("MotherTongue", "SpokenatHome", "MainHomeLanguage"), variable.name="Language") dfw <- dcast(dfl, OEN ~ Langugae , value.var="value" )

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  • Why the macros in Objective-C / Cocoa?

    - by Joe
    I'm coming from a place without macros (Java/Python/C#/Scala) so perhaps my perspective is distorted but... Why are macros used in Cocoa? Two that spring to mind are NSLocalizedString and NSAssert (and STAssert). Would it be so hard / unsuitable to make them functions (which could be inlined)? I suppose I find them a little bizarre as an unnecessary throw-back to C (and yes, I am familiar with the pedigree of Obj-C). Is it just something that was done back in the day or is there a specific reason?

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  • Checking if parsed date is within a date range

    - by Brett Powell
    So I am using a scripting language with c++-like syntax, and I am trying to think of the best way to check if a date is within range. The problem I am running into is that if the current day is in a new month, the check is failing. Here is what my code looks like: if(iMonth >= iStartMonth && iMonth <= iEndMonth) { if(iDay >= iStartDay && iDay <= iEndDay) { if(iYear >= iStartYear && iYear <= iEndYear) { bEnabled = true; return; When I have something like this: Start date: 3 27 2010 End Date: 4 15 2010 Current Date: 3 31 2010 The day check fails because if (iDay <= iEndDay) does not pass. The scripting language doesn't have a lot of time related functions, and I can't compare timestamps because I'm allowing users to put like "03:27:2010" and "04:15:2010" as start/end dates in a config file. I'm assuming I am just not thinking straight and missing an easy fix.

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  • Registering a delegate function with an ISO C++ callback (on mono)

    - by Stick it to THE MAN
    I am thinking of wrapping ISO C++ code in C# class. The only problem so far is how to deal with the C++ callbacks. In .Net languages (C# and Vb.Net), I believe the callback equivalent. Sticking with C# for now, can anyone recommend a way that I can register the C# delegate functions with my ISO C++ code. The ISO C++ code is a notification library, and I want to be able to "push" the notifications to the mono framework (i.e. C# delegates in this case). My underlying assumption is that the mechanism/steps to implement this would be the same for the .Net languages - I'll just have to code the actual delegates in the .Net language of choice - is that assumption correct? Last but not the least, is the question of thread saftey. The underlying ISO C++ code that I am exposing to .Net (mono to be more specific), is both re-ntrant and thread safe - do I have to do anything "extra" to call .Net delegate from my ISO C++ code?

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  • Is it possible to register a user and submit a comment with one form with Wordpress?

    - by zack
    Is it possible to do both registering for an account and submit a comment at the same time? I want the user to be able to do this all on one page to ecourage the registration rather than be discouraged about typing something, not realizing they had to be registered and thus having to leave the page. I think that this could be done by adding register user action to the submit comment action, but not sure how to do it with the prebuilt wordpress add_action or do_action functions. Has anyone tried this, or know of any plug-ins that do this already? I searched but couldn't find anything helpful. Thanks.

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  • Idiomatic approach for structuring Clojure source code

    - by mikera
    I'm interested in how people structure their Clojure source code. Being used to Java, I'm pretty familiar with the paradigm of one class per source code file, bundling all the data and method definitions with appropriate comments and annotations etc. However Clojure offers a lot more flexibility, and I'm not sure how I should structure my project (likely to end up as a medium sized app, maybe 5,000 lines with three or four distinct subsystems) In particular I'm wrestling with: What guidelines should I use to determine whether code should be in a single namespace vs. separated out into different namespaces? Should each protocol/datatype have it's own namespace + source file with associated set of functions? When should I require vs. use other namespaces?

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  • Avoid the use of loops (for) with R

    - by albergali
    Hi, I'm working with R and I have a code like this: i<-1 j<-1 for (i in 1:10) for (j in 1:100) if (data[i] == paths[j,1]) cluster[i,4] <- paths[j,2] where : data is a vector with 100 rows and 1 column paths is a matrix with 100 rows and 5 columns cluster is a matrix with 100 rows and 5 columns My question is: how could I avoid the use of "for" loops to iterate through the matrix? I don't know whether apply functions (lapply, tapply...) are useful in this case. This is a problem when j=10000 for example, because execution time is very long. Thank you

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  • Group SQL tables in Microsoft SQL Server Management Studio object explorer

    - by MainMa
    I have a table which has approximately sixty tables, and other tables are added constantly. Each table is a part of a schema. A such quantity of tables makes it difficult to use Microsoft SQL Server Management Studio 2008. For example, I must scroll up in object explorer to access database related functions, or scroll down each time I need to access Views or Security features. Is it possible to group several tables to be able to expand or collapse them in Object Explorer? Maybe a folder may be displayed for each schema, letting collapse the folders I don't need to use?

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  • In Python, how to use a C++ function which returns an allocated array of structs via a ** parameter?

    - by Jon-Eric
    I'd like to use some existing C++ code, NvTriStrip, in a Python tool. SWIG easily handles the functions with simple parameters, but the main function, GenerateStrips, is much more complicated. What do I need to put in the SWIG interface file to indicate that primGroups is really an output parameter and that it must be cleaned up with delete[]? /////////////////////////////////////////////////////////////////////////// // GenerateStrips() // // in_indices: input index list, the indices you would use to render // in_numIndices: number of entries in in_indices // primGroups: array of optimized/stripified PrimitiveGroups // numGroups: number of groups returned // // Be sure to call delete[] on the returned primGroups to avoid leaking mem // bool GenerateStrips( const unsigned short* in_indices, const unsigned int in_numIndices, PrimitiveGroup** primGroups, unsigned short* numGroups, bool validateEnabled = false ); FYI, here is the PrimitiveGroup declaration: enum PrimType { PT_LIST, PT_STRIP, PT_FAN }; struct PrimitiveGroup { PrimType type; unsigned int numIndices; unsigned short* indices; PrimitiveGroup() : type(PT_STRIP), numIndices(0), indices(NULL) {} ~PrimitiveGroup() { if(indices) delete[] indices; indices = NULL; } };

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  • Generator speed in python 3

    - by Will
    Hello all, I am going through a link about generators that someone posted. In the beginning he compares the two functions below. On his setup he showed a speed increase of 5% with the generator. I'm running windows XP, python 3.1.1, and cannot seem to duplicate the results. I keep showing the "old way"(logs1) as being slightly faster when tested with the provided logs and up to 1GB of duplicated data. Can someone help me understand whats happening differently? Thanks! def logs1(): wwwlog = open("big-access-log") total = 0 for line in wwwlog: bytestr = line.rsplit(None,1)[1] if bytestr != '-': total += int(bytestr) return total def logs2(): wwwlog = open("big-access-log") bytecolumn = (line.rsplit(None,1)[1] for line in wwwlog) getbytes = (int(x) for x in bytecolumn if x != '-') return sum(getbytes)

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  • Looking for a C# code parser

    - by Blindy
    I'm looking for a set of classes (preferably in the .net framework) that will parse C# code and return a list of functions with parameters, classes with their methods, properties etc. Ideally it would provide all that's needed to build my own intellisense. I have a feeling something like this should be in the .net framework, given all the reflection stuff they offer, but if not then an open source alternative is good enough. What I'm trying to build is basically something like Snippet Compiler, but with a twist. I'm trying to figure out how to get the code dom first. I tried googling for this but I'm not sure what the correct term for this is so I came up empty.

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  • heirarchial data from self referencing table in tree form

    - by Beta033
    Ii looks like this has been asked and answered in all the simple cases, excluding the one that i'm having trouble with. I've tried using a recursive CTE to generate this, however maybe a cursor would be better? or maybe a set of recursive functions will do the trick? Can this be done in a cte? consider the following table PrimaryKey ParentKey 1 NULL 2 1 3 6 4 7 5 2 6 1 7 NULL should yield PK 1 -2 --5 -6 --3 7 -4 where the number of - marks equal the depth, my primary difficulty is the ordering.

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