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  • Perl 500 internal server error. Something wrong with my code.

    - by Nitish
    I get a 500 internal server error when I try to run the code below in a web server which supports perl: #! /usr/bin/perl use LWP; my $ua = LWP::UserAgent->new; $ua->agent("TestApp/0.1 "); $ua->env_proxy(); my $req = HTTP::Request->new(POST => 'http://www.google.com/loc/json'); $req->content_type('application/jsonrequest'); $req->content('{ "cell_towers": [{"location_area_code": "55000", "mobile_network_code": "95", "cell_id": "20491", "mobile_country_code": "404"}], "version": "1.1.0", "request_address": "true"}'); my $res = $ua->request($req); if ($res->is_success) { print $res->content,"\n"; } else { print $res->status_line, "\n"; return undef; } But there is no error when I run the code below: #! /usr/bin/perl use CGI::Carp qw(fatalsToBrowser); print "Content-type: text/html\n\n"; print "<HTML>\n"; print "<HEAD><TITLE>Hello World!</TITLE></HEAD>\n"; print "<BODY>\n"; print "<H2>Hello World!</H2> <br /> \n"; foreach $key (sort keys(%ENV)) { print "$key = $ENV{$key}<p>" ; } print "</BODY>\n"; print "</HTML>\n"; So I think there is some problem with my code. When I run the first perl script in my local machine with the -wc command, it says that the syntax is OK. Help me please.

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  • Could someone explain gtk2hs drag and drop to me, the listDND.hs demo just isn't doing it for me?

    - by Tom Carstens
    As the title says, I just don't get DND (or rather I understand the concept and I understand the order of callbacks, I just don't understand how to setup DND for actual usage.) I'd like to say that I've done DND stuff before in C, but considering I never really got that working... So I'm trying (and mostly succeeding, save DND) to write a text editor (using gtksourceview, because it has built in code highlighting.) Reasons are below if you want them. Anyways, there's not really a good DND demo or tutorial available for gtk2hs (listDND.hs just doesn't translate well in my head.) So what I'm asking is for code that demonstrates simple DND on a window widget (for example.) Ideally, it should accept drops from other windows (such as Thunar) and print out the information in string form. I think I can take it from there... Reasons: I'm running a fairly light weight setup, dwm and a few gtk+2 programs. I really don't want to have to pull in gtk+3 to get the current gedit from the repos (Arch Linux.) Currently, I'm using geany for all of my text editing needs, however, geany is a bit heavy for editing config files. Further, geany doesn't care for my terminal of choice (st;) so I don't even get the benefit of using it as an IDE. Meaning I'd like a lightweight text editor with syntax highlighting. I could configure emacs or vim or something, but that seems to me to be more of a hack then a proper solution. Thus my project was born. It's mostly working (aside from DND, all that's left is proper multi-tab support.) Admittedly, I could probably work this out if I wrote it in C, but there isn't that much state in a text editor so Haskell's been working fine with almost no need for mutable variables.

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  • Three most critical programming concepts

    - by Todd
    I know this has probably been asked in one form or fashion but I wanted to pose it once again within the context of my situation (and probably others here @ SO). I made a career change to Software Engineering some time ago without having an undergrad or grad degree in CS. I've supplemented my undergrad and grad studies in business with programming courses (VB, Java,C, C#) but never performed academic coursework in the other related disciplines (algorithms, design patterns, discrete math, etc.)...just mostly self-study. I know there are several of you who have either performed interviews and/or made hiring decisions. Given recent trends in demand, what would you say are the three most essential Comp Sci concepts that a developer should have a solid grasp of outside of language syntax? For example, I've seen blog posts of the "Absolute minimum X that every programmer must know" variety...that's what I'm looking for. Again if it's truly a redundancy please feel free to close; my feelings won't be hurt. (Closest ones I could find were http://stackoverflow.com/questions/164048/basic-programming-algorithmic-concepts- which was geared towards a true beginner, and http://stackoverflow.com/questions/648595/essential-areas-of-knowledge-which I didn't feel was concrete enough). Thanks in advance all! T.

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  • C#: Non-constructed generics as properties (eg. List<T>)

    - by Dav
    The Problem It's something I came across a while back and was able to work around it somehow. But now it came back, feeding on my curiosity - and I'd love to have a definite answer. Basically, I have a generic dgv BaseGridView<T> : DataGridView where T : class. Constructed types based on the BaseGridView (such as InvoiceGridView : BaseGridView<Invoice>) are later used in the application to display different business objects using the shared functionality provided by BaseGridView (like virtual mode, buttons, etc.). It now became necessary to create a user control that references those constructed types to control some of the shared functionality (eg. filtering) from BaseGridView. I was therefore hoping to create a public property on the user control that would enable me to attach it to any BaseGridView in Designer/code: public BaseGridView<T> MyGridView { get; set; }. The trouble is, it doesn't work :-) When compiled, I get the following message: The type or namespace name 'T' could not be found (are you missing a using directive or an assembly reference?) Solutions? I realise I could extract the shared functionality to an interface, mark BaseGridView as implementing that interface, and then refer to the created interface in my uesr control. But I'm curious if there exists some arcane C# command/syntax that would help me achieve what I want - without polluting my solution with an interface I don't really need :-)

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  • Design by contracts and constructors

    - by devoured elysium
    I am implementing my own ArrayList for school purposes, but to spice up things a bit I'm trying to use C# 4.0 Code Contracts. All was fine until I needed to add Contracts to the constructors. Should I add Contract.Ensures() in the empty parameter constructor? public ArrayList(int capacity) { Contract.Requires(capacity > 0); Contract.Ensures(Size == capacity); _array = new T[capacity]; } public ArrayList() : this(32) { Contract.Ensures(Size == 32); } I'd say yes, each method should have a well defined contract. On the other hand, why put it if it's just delegating work to the "main" constructor? Logicwise, I wouldn't need to. The only point I see where it'd be useful to explicitly define the contract in both constructors is if in the future we have Intelisense support for contracts. Would that happen, it'd be useful to be explicit about which contracts each method has, as that'd appear in Intelisense. Also, are there any books around that go a bit deeper on the principles and usage of Design by Contracts? One thing is having knowledge of the syntax of how to use Contracts in a language (C#, in this case), other is knowing how and when to use it. I read several tutorials and Jon Skeet's C# in Depth article about it, but I'd like to go a bit deeper if possible. Thanks

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  • VB.net avoiding cross thread exception with extension method

    - by user574632
    Hello I am trying to implement a solution for updating form controls without using a delegate. I am attempting to use the 1st solution on this page: http://www.dreamincode.net/forums/blog/143/entry-2337-handling-the-dreaded-cross-thread-exception/ Imports System.ComponentModel Imports System.Runtime.CompilerServices Public Module MyInvoke <Extension()> _ Public Sub CustomInvoke(Of T As ISynchronizeInvoke)(ByVal control As T, ByVal toPerform As Action(Of T)) If control.InvokeRequired Then control.Invoke(toPerform, New Object() {control}) toPerform(control) End If End Sub End Module The site gives this as example of how to use: Label1.CustomInvoke(l => l.Text = "Hello World!") But i get 'l' is not declared error. As you can see im very new to VB or any OOP. I can get the second solution on that page to work (using delegates) but i have quite a few things to do in this thread and it seems like i would need to write a new delegate sub for each thing, which seems wasteful. What i need to do is select the 1st item from a combobox, update a textbox.text with the selected item, and pass the selected item to a function. Then wait for x seconds and start again, selecting the second item. I can get it to work in a single threaded application, but i need the interface to remain responsive. Any help greatly appreciated. EDIT: OK so changing the syntax worked for the example. However if i change it from Label1.CustomInvoke(Sub(l) l.text = "hello world!") (which worked just fine) to: Dim indexnumber As Integer = 0 ComboBox1.CustomInvoke(Sub(l) l.SelectedIndex = indexnumber) I get a cross threading error as though i didnt even use this method: Cross-thread operation not valid: Control 'ComboBox1' accessed from a thread other than the thread it was created on. So now im back to where i started? Any further help very much appreciated.

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  • Calling a non-activeX DLL in a VB6 application in Vista/Win7

    - by user1490330
    I have a VB6 app that utilizes a non-activeX DLL (non-registering). It's declared via the classic Public Declare Function "Function Name" Lib "Library.DLL" syntax. On my dev machine (XP) it works fine but when I deploy to Vista or Win7 I'm constantly greeted with a Run Time Error 48 - File Not Found for the DLL in question. I have tried copying that DLL to every directory I can think of including every environment path on the test machine and the app path too. These are all 32-bit test environments so it's not a SysWow64 issue. Possibly throwing a wrench into the mix is the fact that the application in question is an Outlook COM Addin. I managed to install VB6 on Win7 and was able to run a tiny sample app that utilizes this DLL (outside of the Outlook process) so I know it works PROVIDED the DLL is located in App path. If I call App.Path from my DLL when I run it on the test environment it shows, to no surprise, my installation directory however the DLL is there. I tried turning off UAC. I tried making the App.Path directory permissions open to everyone, still no dice.

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  • Entity Framework LINQ Query using Custom C# Class Method - Once yes, once no - because executing on the client or in SQL?

    - by BrooklynDev
    I have two Entity Framework 4 Linq queries I wrote that make use of a custom class method, one works and one does not: The custom method is: public static DateTime GetLastReadToDate(string fbaUsername, Discussion discussion) { return (discussion.DiscussionUserReads.Where(dur => dur.User.aspnet_User.UserName == fbaUsername).FirstOrDefault() ?? new DiscussionUserRead { ReadToDate = DateTime.Now.AddYears(-99) }).ReadToDate; } The linq query that works calls a from after a from, the equivalent of SelectMany(): from g in oc.Users.Where(u => u.aspnet_User.UserName == fbaUsername).First().Groups from d in g.Discussions select new { UnReadPostCount = d.Posts.Where(p => p.CreatedDate > DiscussionRepository.GetLastReadToDate(fbaUsername, p.Discussion)).Count() }; The query that does not work is more like a regular select: from d in oc.Discussions where d.Group.Name == "Student" select new { UnReadPostCount = d.Posts.Where(p => p.CreatedDate > DiscussionRepository.GetLastReadToDate(fbaUsername, p.Discussion)).Count(), }; The error I get is: LINQ to Entities does not recognize the method 'System.DateTime GetLastReadToDate(System.String, Discussion)' method, and this method cannot be translated into a store expression. My question is, why am I able to use my custom GetLastReadToDate() method in the first query and not the second? I suppose this has something to do with what gets executed on the db server and what gets executed on the client? These queries seem to use the GetLastReadToDate() method so similarly though, I'm wondering why would work for the first and not the second, and most importantly if there's a way to factor common query syntax like what's in the GetLastReadToDate() method into a separate location to be reused in several different places LINQ queries. Please note all these queries are sharing the same object context.

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  • Building Active Record Conditions in an array - private method 'scan' called error

    - by Nick
    Hi, I'm attempting to build a set of conditions dynamically using an array as suggested in the first answer here: http://stackoverflow.com/questions/1658990/one-or-more-params-in-model-find-conditions-with-ruby-on-rails. However I seem to be doing something incorrectly and I'm not sure if what I'm trying is fundamentally unsound or if I'm simply botching my syntax. I'm simplifying down to a single condition here to try to illustrate the issue as I've tried to built a simple Proof of concept along these lines before layering on the 5 different condition styles I'm contending with. This works: excluded.push 12 excluded.push 30 @allsites = Site.all(:conditions => ["id not in (?)", excluded]) This results in a private method 'scan' called error: excluded.push 12 excluded.push 30 conditionsSet << ["id not in (?)", excluded] @allsites = Site.all(:conditions => conditionsSet) Thanks for any advice. I wasn't sure if the proper thing was to put this as a followup item to the related question/answers I noted at the top. Since I've got a problem not an answer. If there is a better way to post this related to the existing post please let me know.

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  • error catching exception while System.out.print

    - by user1702633
    I have 2 classes, one that implements a double lookup( int i); and one where I use that lookup(int i) in solving a question, or in this case printing the lookup values. This case is for an array. So I read the exception documentation or google/textbook and come with the following code: public double lookup(int i) throws Exception { if( i > numItems) throw new Exception("out of bounds"); return items[i]; } and take it over to my class and try to print my set, where set is a name of the object type I define in the class above. public void print() { for (int i = 0; i < set.size() - 1; i++) { System.out.print(set.lookup(i) + ","); } System.out.print(set.lookup(set.size())); } I'm using two print()'s to avoid the last "," in the print, but am getting an unhandled exception Exception (my exception's name was Exception) I think I have to catch my exception in my print() but cannot find the correct formatting online. Do I have to write catch exception Exception? because that gives me a syntax error saying invalid type on catch. Sources like http://docs.oracle.com/javase/tutorial/essential/exceptions/ are of little help to me, I'm can't seem to grasp what the text is telling me. I'm also having trouble finding sources with multiple examples where I can actually understand the coding in the examples. so could anybody give me a source/example for the above catch phrase and perhaps a decent source of examples for new Java programmers? my book is horrendous and I cannot seem to find an understandable example for the above catch phrase online.

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  • summing functions handles in matlab

    - by user552231
    Hi I am trying to sum two function handles, but it doesn't work. for example: y1=@(x)(x*x); y2=@(x)(x*x+3*x); y3=y1+y2 The error I receive is "??? Undefined function or method 'plus' for input arguments of type 'function_handle'." This is just a small example, in reality I actually need to iteratively sum about 500 functions that are dependent on each other. EDIT The solution by Clement J. indeed works but I couldn't manage to generalize this into a loop and ran into a problem. I have the function s=@(x,y,z)((1-exp(-x*y)-z)*exp(-x*y)); And I have a vector v that contains 536 data points and another vector w that also contains 536 data points. My goal is to sum up s(v(i),y,w(i)) for i=1...536 Thus getting one function in the variable y which is the sum of 536 functions. The syntax I tried in order to do this is: sum=@(y)(s(v(1),y,z2(1))); for i=2:536 sum=@(y)(sum+s(v(i),y,z2(i))) end

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  • Can Haskell's monads be thought of as using and returning a hidden state parameter?

    - by AJM
    I don't understand the exact algebra and theory behind Haskell's monads. However, when I think about functional programming in general I get the impression that state would be modelled by taking an initial state and generating a copy of it to represent the next state. This is like when one list is appended to another; neither list gets modified, but a third list is created and returned. Is it therefore valid to think of monadic operations as implicitly taking an initial state object as a parameter and implicitly returning a final state object? These state objects would be hidden so that the programmer doesn't have to worry about them and to control how they gets accessed. So, the programmer would not try to copy the object representing the IO stream as it was ten minutes ago. In other words, if we have this code: main = do putStrLn "Enter your name:" name <- getLine putStrLn ( "Hello " ++ name ) ...is it OK to think of the IO monad and the "do" syntax as representing this style of code? putStrLn :: IOState -> String -> IOState getLine :: IOState -> (IOState, String) main :: IOState -> IOState -- main returns an IOState we can call "state3" main state0 = putStrLn state2 ("Hello " ++ name) where (state2, name) = getLine state1 state1 = putStrLn state0 "Enter your name:"

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  • C++ Constructor With Parameters Won't Initialize, Errors C2059 and C2228

    - by Some Girl
    I'm a C# programmer trying to muddle through C++ to create a Windows Forms Application. I have a Windows Form that makes use of a user-created class. Basically I'm trying to use a constructor that takes parameters, but my form won't let me initialize the object with parameter. Here's the code, hopefully somebody can explain the problem to me because I'm completely baffled... Here's my header file: BankAcct.h public ref class BankAcct { private: int money; public: BankAcct(); BankAcct(int); void Deposit(int); void GetBalance(int&); }; And my definition file: BankAcct.cpp #include "StdAfx.h" #include "BankAcct.h" BankAcct::BankAcct() { money = 0; } BankAcct::BankAcct(int startAmt) { money = startAmt; } void BankAcct::Deposit(int depAmt) { money += depAmt; } void BankAcct::GetBalance(int& balance) { balance = money; } And finally my main form. Won't copy the whole thing, of course, but I'm trying to declare the new bank account object, and start it with a balance of say $50. private: BankAcct myAccount(50); //does not work! WHY?? //private: //BankAcct myAccount; //works then in the form constructor my code is this: public: frmBank(void) { InitializeComponent(); int bal; myAccount.GetBalance(bal); lblBankBalance->Text += Convert::ToString(bal); } I've included the BankAcct.h file at the top of my frmBank.h, what else am I doing wrong here? It works great if I use the default constructor (the one that starts the bank balance at zero). I get the following error messages: error C2059: syntax error: 'constant' and error C2228: left of '.GetBalance' must have class/struct/union Thank you for any and all help on this one!!

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  • Using list() to extract a data.table inside of a function

    - by Nathan VanHoudnos
    I must admit that the data.table J syntax confuses me. I am attempting to use list() to extract a subset of a data.table as a data.table object as described in Section 1.4 of the data.table FAQ, but I can't get this behavior to work inside of a function. An example: require(data.table) ## Setup some test data set.seed(1) test.data <- data.table( X = rnorm(10), Y = rnorm(10), Z = rnorm(10) ) setkey(test.data, X) ## Notice that I can subset the data table easily with literal names test.data[, list(X,Y)] ## X Y ## 1: -0.8356286 -0.62124058 ## 2: -0.8204684 -0.04493361 ## 3: -0.6264538 1.51178117 ## 4: -0.3053884 0.59390132 ## 5: 0.1836433 0.38984324 ## 6: 0.3295078 1.12493092 ## 7: 0.4874291 -0.01619026 ## 8: 0.5757814 0.82122120 ## 9: 0.7383247 0.94383621 ## 10: 1.5952808 -2.21469989 I can even write a function that will return a column of the data.table as a vector when passed the name of a column as a character vector: get.a.vector <- function( my.dt, my.column ) { ## Step 1: Convert my.column to an expression column.exp <- parse(text=my.column) ## Step 2: Return the vector return( my.dt[, eval(column.exp)] ) } get.a.vector( test.data, 'X') ## [1] -0.8356286 -0.8204684 -0.6264538 -0.3053884 0.1836433 0.3295078 ## [7] 0.4874291 0.5757814 0.7383247 1.5952808 But I cannot pull a similar trick for list(). The inline comments are the output from the interactive browser() session. get.a.dt <- function( my.dt, my.column ) { ## Step 1: Convert my.column to an expression column.exp <- parse(text=my.column) ## Step 2: Enter the browser to play around browser() ## Step 3: Verity that a literal X works: my.dt[, list(X)] ## << not shown >> ## Step 4: Attempt to evaluate the parsed experssion my.dt[, list( eval(column.exp)] ## Error in `rownames<-`(`*tmp*`, value = paste(format(rn, right = TRUE), (from data.table.example.R@1032mCJ#7) : ## length of 'dimnames' [1] not equal to array extent return( my.dt[, list(eval(column.exp))] ) } get.a.dt( test.data, "X" ) What am I missing? Update: Due to some confusion as to why I would want to do this I wanted to clarify. My use case is when I need to access a data.table column when when I generate the name. Something like this: set.seed(2) test.data[, X.1 := rnorm(10)] which.column <- 'X' new.column <- paste(which.column, '.1', sep="") get.a.dt( test.data, new.column ) Hopefully that helps.

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  • Symfony generating database from model

    - by Sergej Jevsejev
    Hello, I am having troubles generating a simple database form model. I am using: Doctrine on Symfony 1.4.4 MySQL Workbench 5.2.16 with Doctrine Export 0.4.2dev So my ERL Model is: http://img708.imageshack.us/img708/1716/tmg.png Genereted YAML file: --- detect_relations: true options: collate: utf8_unicode_ci charset: utf8 type: InnoDB Course: columns: id: type: integer(4) primary: true notnull: true autoincrement: true name: type: string(255) notnull: true keywords: type: string(255) notnull: true summary: type: clob(65535) notnull: true Lecture: columns: id: type: integer(4) primary: true notnull: true autoincrement: true course_id: type: integer(4) primary: true notnull: true name: type: string(255) notnull: true description: type: string(255) notnull: true url: type: string(255) relations: Course: class: Course local: course_id foreign: id foreignAlias: Lectures foreignType: many owningSide: true User: columns: id: type: integer(4) primary: true unique: true notnull: true autoincrement: true firstName: type: string(255) notnull: true lastName: type: string(255) notnull: true email: type: string(255) unique: true notnull: true designation: type: string(1024) personalHeadline: type: string(1024) shortBio: type: clob(65535) UserCourse: tableName: user_has_course columns: user_id: type: integer(4) primary: true notnull: true course_id: type: integer(4) primary: true notnull: true relations: User: class: User local: user_id foreign: id foreignAlias: UserCourses foreignType: many owningSide: true Course: class: Course local: course_id foreign: id foreignAlias: UserCourses foreignType: many owningSide: true And no matter what I try this error occurs after: symfony doctrine:build --all --no-confirmation SQLSTATE[42000]: Syntax error or access violation: 1072 Key column 'user_userid' doesn't exist in table. Failing Query: "ALTER TABLE user_has_course ADD CONSTRAINT user_has_course_user_userid_user_id FOREIGN KEY (user_userid) REFERENCES user(id)". Failing Query: ALTER TABLE user_has_course ADD CONSTRAINT user_has_cou rse_user_userid_user_id FOREIGN KEY (user_userid) REFERENCES user(id) Currently I am studying Symfony, and stuck with this error. Please help.

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  • LINQ-to-SQL - Join, Count

    - by ile
    I have following query: var result = ( from role in db.Roles join user in db.Users on role.RoleID equals user.RoleID where user.CreatedByUserID == userID orderby user.FirstName ascending select new UserViewModel { UserID = user.UserID, PhotoID = user.PhotoID.ToString(), FirstName = user.FirstName, LastName = user.LastName, FullName = user.FirstName + " " + user.LastName, Email = user.Email, PhoneNumber = user.Phone, AccessLevel = role.Name }); Now, I need to modify this query... Other table I have is table Deals. I would like to count how many deals user created last month and last year. I tried something like this: var result = ( from role in db.Roles join user in db.Users on role.RoleID equals user.RoleID //join dealsYear in db.Deals on date.Year equals dealsYear.DateCreated.Year join dealsYear in ( from deal in db.Deals group deal by deal.DateCreated into d select new { DateCreated = d.Key, dealsCount = d.Count() } ) on date.Year equals dealsYear.DateCreated.Year into dYear join dealsMonth in ( from deal in db.Deals group deal by deal.DateCreated into d select new { DateCreated = d.Key, dealsCount = d.Count() } ) on date.Month equals dealsMonth.DateCreated.Month into dMonth where user.CreatedByUserID == userID orderby user.FirstName ascending select new UserViewModel { UserID = user.UserID, PhotoID = user.PhotoID.ToString(), FirstName = user.FirstName, LastName = user.LastName, FullName = user.FirstName + " " + user.LastName, Email = user.Email, PhoneNumber = user.Phone, AccessLevel = role.Name, DealsThisYear = dYear, DealsThisMonth = dMonth }); but here is even syntax not correct. Any idea? Btw, is there any good book of LINQ to SQL with examples?

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  • What are the best tricks for learning how to -think- in Objective-C?

    - by Braintapper
    Before I get flamed out for not checking previous questions, I have read most of the tutorials, and have Hillegass' book, as well as O'Reilly's book on it. I'm not asking for tips on Cocoa or what IDE to use. Where my issue lies - my 'mental muscle memory' is making it hard for me to read Objective-C code. I have no problems at all reading Java and C code and understanding what's going on. Maybe I'm getting to old to learn a new syntax, but it's a struggle shifting mental gears and looking at Objective-C code and just "getting it" (I thought it might be an isolated case, but I have other friends who are seasoned devs who have said the same thing). Are there any tricks that any non-Objective-C programmers who now know Objective-C used to help process the syntactical differences when learning it? For some reason, I get dyslexic when reading Objective-C code. Maybe I'm not meant to be able to learn it (and that's ok too). I was hoping/wondering if there might be others who have had the same experience.

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  • c# Why can't open generic types be passed as parameters?

    - by Rich Oliver
    Why can't open generic types be passed as parameters. I frequently have classes like: public class Example<T> where T: BaseClass { public int a {get; set;} public List<T> mylist {get; set;} } Lets say BaseClass is as follows; public BaseClass { public int num; } I then want a method of say: public int MyArbitarySumMethod(Example example)//This won't compile Example not closed { int sum = 0; foreach(BaseClass i in example.myList)//myList being infered as an IEnumerable sum += i.num; sum = sum * example.a; return sum; } I then have to write an interface just to pass this one class as a parameter as follows: public interface IExample { public int a {get; set;} public IEnumerable<BaseClass> myIEnum {get;} } The generic class then has to be modified to: public class Example<T>: IExample where T: BaseClass { public int a {get; set;} public List<T> mylist {get; set;} public IEnumerable<BaseClass> myIEnum {get {return myList;} } } That's a lot of ceremony for what I would have thought the compiler could infer. Even if something can't be changed I find it psychologically very helpful if I know the reasons / justifications for the absence of Syntax short cuts.

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  • overloading "<<" with a struct (no class) cout style

    - by monkeyking
    I have a struct that I'd like to output using either 'std::cout' or some other output stream. Is this possible without using classes? Thanks #include <iostream> #include <fstream> template <typename T> struct point{ T x; T y; }; template <typename T> std::ostream& dump(std::ostream &o,point<T> p) const{ o<<"x: " << p.x <<"\ty: " << p.y <<std::endl; } template<typename T> std::ostream& operator << (std::ostream &o,const point<T> &a){ return dump(o,a); } int main(){ point<double> p; p.x=0.1; p.y=0.3; dump(std::cout,p); std::cout << p ;//how? return 0; } I tried different syntax' but I cant seem to make it work.

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  • getting another website data to manipulate it's value in perl

    - by aun ali
    use CGI qw(:standard); use CGI::Carp qw(fatalsToBrowser warningsToBrowser); our @a=param(src="http://fxrates.forexpros.com/index.php?pairs_ids=1525=last_update"); print header(),start_html('results.pl'); $a=http://fxrates.forexpros.com/index.php?pairs_ids=1525=last_update; '<iframe frameborder="0" scrolling="no" height="95" width="213" allowtransparency="true" marginwidth="0" marginheight="0" src="http://fxrates.forexpros.com/index.php?pairs_ids=1525;&header-text-color=%23FFFFFF&curr-name-color=%230059b0&inner-text-color=%23000000&green-text-color=%232A8215&green-background=%23B7F4C2&red-text-color=%23DC0001&red-background=%23FFE2E2&inner-border-color=%23CBCBCB&border-color=%23cbcbcb&bg1=%23F6F6F6&bg2=%23ffffff&bid=hide&ask=hide&last=hide&high=hide&low=hide&change=hide&change_in_percents=hide&last_update=show"></iframe><br /><div style="width:213"><span style="float:left"><span style="font-size: 11px;color: #333333;text-decoration: none;">The <a href="http://www.forexpros.com/quotes" target="_blank" style="font-size: 11px;color: #06529D; font-weight: bold;" class="underline_link">Forex Quotes</a> are Powered by Forexpros - The Leading Financial Portal.</span></span></div>'; print '<br/>'; print "$a"; print end_html();' getting error: Can't modify constant item in scalar assignment at livedata.pl line 4, near ""http://fxrates.forexpros.com/index.php?pairs_ids=1525=last_update")" syntax error at livedata.pl line 6, near "http:" Execution of livedata.pl aborted due to compilation errors.

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  • What's the best way to get a bunch of rows from MySQL if you have an array of integer primary keys?

    - by Evan P.
    I have a MySQL table with an auto-incremented integer primary key. I want to get a bunch of rows from the table based on an array of integers I have in memory in my program. The array ranges from a handful to about 1000 items. What's the most efficient query syntax to get the rows? I can think of a few: "SELECT * FROM thetable WHERE id IN (1, 2, 3, 4, 5)" (this is what I do now) "SELECT * FROM thetable where id = 1 OR id = 2 OR id = 3" Multiple queries of the form "SELECT * FROM thetable WHERE id = 1". Probably the most friendly to the query cache, but expensive due to having lots of query parsing. A union, like "SELECT * FROM thetable WHERE id = 1 UNION SELECT * FROM thetable WHERE id = 2 ..." I'm not sure if MySQL caches the results of each query; it's also the most verbose format. I think using the NoSQL interface in MySQL 5.6+ would be the most efficient way to do this, but I'm not yet up to MySQL 5.6.

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  • Using linq2xml to query a single item deep within

    - by BrettRobi
    I'm wondering if there is a robust and graceful way using linq2xml to query an item deep within an xml hierarchy. For example: <?xml version="1.0" encoding="utf-8" ?> <data> <core id="01234"> <field1>some data</field1> <field2>more data</field2> <metadata> <response> <status code="0">Success</status> <content> <job>f1b5c3f8-e6b1-4ae4-905a-a7c5de3f13c6</job> <id>id of the content</id> </content> </response> </metadata> </core> </data> With this xml how do I query the value of without using something like this: var doc = XElement.Load("file.xml"); string id = (string)doc.Element("core") .Element("metadata") .Element("response") .Element("content") .Element("id"); I don't like the above approach because it is error prone (throws exception if any tag is missing in the hierarchy) and honestly ugly. Is there a more robust and graceful approach, perhaps using the sql-like syntax of linq?

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  • Shaping EF LINQ Query Results Using Multi-Table Includes

    - by sisdog
    I have a simple LINQ EF query below using the method syntax. I'm using my Include statement to join four tables: Event and Doc are the two main tables, EventDoc is a many-to-many link table, and DocUsage is a lookup table. My challenge is that I'd like to shape my results by only selecting specific columns from each of the four tables. But, the compiler is giving a compiler is giving me the following error: 'System.Data.Objects.DataClasses.EntityCollection does not contain a definition for "Doc' and no extension method 'Doc' accepting a first argument of type 'System.Data.Objects.DataClasses.EntityCollection' could be found. I'm sure this is something easy but I'm not figuring it out. I haven't been able to find an example of someone using the multi-table include but also shaping the projection. Thx,Mark var qry= context.Event .Include("EventDoc.Doc.DocUsage") .Select(n => new { n.EventDate, n.EventDoc.Doc.Filename, //<=COMPILER ERROR HERE n.EventDoc.Doc.DocUsage.Usage }) .ToList(); EventDoc ed; Doc d = ed.Doc; //<=NO COMPILER ERROR SO I KNOW MY MODEL'S CORRECT DocUsage du = d.DocUsage;

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  • How do I insert null fields with Perl's DBD::Pg?

    - by User1
    I have a Perl script inserting data into Postgres according to a pipe delimited text file. Sometimes, a field is null (as expected). However, Perl makes this field into an empty string and the Postgres insert statement fails. Here's a snippet of code: use DBI; #Connect to the database. $dbh=DBI-connect('dbi:Pg:dbname=mydb','mydb','mydb',{AutoCommit=1,RaiseError=1,PrintError=1}); #Prepare an insert. $sth=$dbh-prepare("INSERT INTO mytable (field0,field1) SELECT ?,?"); while (<){ #Remove the whitespace chomp; #Parse the fields. @field=split(/\|/,$_); print "$_\n"; #Do the insert. $sth-execute($field[0],$field[1]); } And if the input is: a|1 b| c|3 EDIT: Use this input instead. a|1|x b||x c|3|x It will fail at b|. DBD::Pg::st execute failed: ERROR: invalid input syntax for integer: "" I just want it to insert a null on field1 instead. Any ideas? EDIT: I simplified the input at the last minute. The old input actually made it work for some reason. So now I changed the input to something that will make the program fail. Also note that field1 is a nullable integer datatype.

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  • Adding Variables to JavaScript in Joomla

    - by Vikram
    Hello friends! This is the script I am using to display an accordion in my Joomla site: <?php defined('JPATH_BASE') or die(); gantry_import('core.gantryfeature'); class GantryFeatureAccordion extends GantryFeature { var $_feature_name = 'accordion'; function init() { global $gantry; if ($this->get('enabled')) { $gantry->addScript('accordion.js'); $gantry->addInlineScript($this->_accordion()); } } function render($position="") { ob_start(); ?> <div id="accordion"> <dl> <?php foreach (glob("templates/rt_gantry_j15/features/accordion/*.php") as $filename) {include($filename);} ?> </dl> </div> <?php return ob_get_clean(); } function _accordion() { global $gantry; $js = " jQuery.noConflict(); (function($){ $(document).ready(function () { $('#accordion').easyAccordion({ slideNum: true, autoStart: true, slideInterval: 4000 }); }); })(jQuery); "; return $js; } } I want to call these three values in the templateDetails.XML file as a user input. slideNum: true, autoStart: true, slideInterval: 4000 Like this in the templateDetails.xml file: <param name="accordion" type="chain" label="ACCORDION" description="ACCORDION_DESC"> <param name="slideNum" type="text" default="true" label="Offset Y" class="text-short" /> <param name="autoStart" type="text" default="true" label="Offset Y" class="text-short" /> <param name="autoStart" type="text" default="4000" label="Offset Y" class="text-short" /> </param> How can I do so? What will be the exact syntax for the same. I am very new to programming ans specially to JavaScript. Kindly help.

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