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  • Ruby IRB - Requires and Scope

    - by tyndall
    Trying to understand this problem I'm running into. I create file welcome.rb. The contents of this file: welcome_message = "hi there" I then launch an irb session. And type require 'welcome'. That works fine. Then I type: puts welcome_message I get the error message undefined local variable or method `welcome_message' for main:Object What is the best way to bring in predefined variables and have initialization work done when you require something into your irb session. Global variables didn't seem like the right path.

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  • Scope quandary with namespaces, function templates, and static data

    - by Adrian McCarthy
    This scoping problem seems like the type of C++ quandary that Scott Meyers would have addressed in one of his Effective C++ books. I have a function, Analyze, that does some analysis on a range of data. The function is called from a few places with different types of iterators, so I have made it a template (and thus implemented it in a header file). The function depends on a static table of data, AnalysisTable, that I don't want to expose to the rest of the code. My first approach was to make the table a static const inside Analysis. namespace MyNamespace { template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { static const int AnalysisTable[] = { /* data */ }; ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace It appears that the compiler creates a copy of AnalysisTable for each instantiation of Analyze, which is wasteful of space (and, to a small degree, time). So I moved the table outside the function like this: namespace MyNamespace { const int AnalysisTable[] = { /* data */ }; template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace There's only one copy of the table now, but it's exposed to the rest of the code. I'd rather keep this implementation detail hidden, so I introduced an unnamed namespace: namespace MyNamespace { namespace { // unnamed to hide AnalysisTable const int AnalysisTable[] = { /* data */ }; } // unnamed namespace template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace But now I again have multiple copies of the table, because each compilation unit that includes this header file gets its own. If Analyze weren't a template, I could move all the implementation detail out of the header file. But it is a template, so I seem stuck. My next attempt was to put the table in the implementation file and to make an extern declaration within Analyze. // foo.h ------ namespace MyNamespace { template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { extern const int AnalysisTable[]; ... // implementation uses AnalysisTable return result; } } // namespace MyNamespace // foo.cpp ------ #include "foo.h" namespace MyNamespace { const int AnalysisTable[] = { /* data */ }; } This looks like it should work, and--indeed--the compiler is satisfied. The linker, however, complains, "unresolved external symbol AnalysisTable." Drat! (Can someone explain what I'm missing here?) The only thing I could think of was to give the inner namespace a name, declare the table in the header, and provide the actual data in an implementation file: // foo.h ----- namespace MyNamespace { namespace PrivateStuff { extern const int AnalysisTable[]; } // unnamed namespace template <typename InputIterator> int Analyze(InputIterator begin, InputIterator end) { ... // implementation uses PrivateStuff::AnalysisTable return result; } } // namespace MyNamespace // foo.cpp ----- #include "foo.h" namespace MyNamespace { namespace PrivateStuff { const int AnalysisTable[] = { /* data */ }; } } Once again, I have exactly one instance of AnalysisTable (yay!), but other parts of the program can access it (boo!). The inner namespace makes it a little clearer that they shouldn't, but it's still possible. Is it possible to have one instance of the table and to move the table beyond the reach of everything but Analyze?

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  • Variable Scope Problem, iPhone

    - by Stumf
    Hello all, I need some help here so I will do my best to explain. I have worked on this all day and had no success (just learning!) I have: NSArray *getValue(NSString *iosearch) { ................................. ................................... \\ More code here } - (NSString *) serialnumber { NSArray *results = getValue(@"serial-number"); if (results) return [results objectAtIndex:0]; return nil; } - (NSString *) backlightlevel { NSArray *results = getValue(@"backlight-level"); if (results) return [results objectAtIndex:0]; return nil; } I have a tableView set up and want to display my array in it so I then have: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {............. ......................................................... cell.text = [results objectAtIndex:indexPath.row]; // error results undeclared here return cell; } The problem is I get results undeclared as indicated above. I also can't figure how I could get serialnumber and backlightlevel to display on the click of a button or even at load. My attempts have thrown back errors like error: 'serialnumber' undeclared (first use in this function) and warnings like warning: 'return' with a value, in function returning void. Sorry for the long question! Many thanks, Stuart

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  • Sinatra Variable Scope

    - by Ethan Turkeltaub
    Take the following code: ### Dependencies require 'rubygems' require 'sinatra' require 'datamapper' ### Configuration config = YAML::load(File.read('config.yml')) name = config['config']['name'] description = config['config']['description'] username = config['config']['username'] password = config['config']['password'] theme = config['config']['theme'] set :public, 'views/themes/#{theme}/static' ### Models DataMapper.setup(:default, "sqlite3://#{Dir.pwd}/marvin.db") class Post include DataMapper::Resource property :id, Serial property :name, String property :body, Text property :created_at, DateTime property :slug, String end class Page include DataMapper::Resource property :id, Serial property :name, String property :body, Text property :slug, String end DataMapper.auto_migrate! ### Controllers get '/' do @posts = Post.get(:order => [ :id_desc ]) haml :"themes/#{theme}/index" end get '/:year/:month/:day/:slug' do year = params[:year] month = params[:month] day = params[:day] slug = params[:slug] haml :"themes/#{theme}/post.haml" end get '/:slug' do haml :"themes/#{theme}/page.haml" end get '/admin' do haml :"admin/index.haml" end I want to make name, and all those variables available to the entire script, as well as the views. I tried making them global variables, but no dice.

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  • anonymous function variable scope [js, ajax]

    - by arthurprs
    $(".delete").click( function() { var thesender = this; $(thesender).text("Del..."); $.getJSON("ajax.php", {}, function(data) { if (data["result"]) $(thesender).remove(); // variable defined outside else alert('Error!'); } ); return false; } ); This can cause problems if user clicks on another ".delete" before the ajax callback is called?

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  • How do i fix this JS scope in GM_xmlhttpRequest

    - by acidzombie24
    When i run this code alert 2 shows 6 different href links. alert 3 shows the last href 6 times. How do i make it use the same object (linkdom aka thelink) as alert 2. NOTE: This is in a greasemonkey script { var linkdom = thelink; alert('2' + linkdom.getAttribute("href")); GM_xmlhttpRequest({ method: 'GET', url: href, onload: function(resp){ //... alert('3' + linkdom.getAttribute("href")); } }); //... }

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  • Scope of object properties & methods

    - by Anish
    In the article Show love to the object literal, it's said: When we have several scripts in a page, the global variables & functions will get overwritten if their name repeats. One solution is to make the variables as properties & functions as methods of an object, and access them via the object name. But will this prevent the issue of variables getting into the global namespace? <script> var movie = { name: "a", trailer: function(){ //code } }; </script> In the above code which elements gets added to the global namespace? a) Just the object name - movie b) Object name as well as the properties and methods inside it – movie, movie.name, movie.trailer()

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  • javascript scope problem when lambda function refers to a variable in enclosing loop

    - by Stefan Blixt
    First question on stackoverflow :) Hope I won't embarrass myself... I have a javascript function that loads a list of albums and then it creates a list item for each album. The list item should be clickable, so I call jQuery's click() with a function that does stuff. I do this in a loop. My problem is that all items seem to get the same click function, even though I try to make a new one that does different stuff in each iteration. Another possibility is that the iteration variable is global somehow, and the function refers to it. Code below. debug() is just an encapsulation of Firebug's console.debug(). function processAlbumList(data, c) { for (var album in data) { var newAlbum = $('<li class="albumLoader">' + data[album].title + '</li>').clone(); var clickAlbum = function() { debug("contents: " + album); }; debug("Album: " + album + "/" + data[album].title); $('.albumlist').append(newAlbum); $(newAlbum).click(clickAlbum); } } Here is a transcript of what it prints when the above function runs, after that are some debug lines caused by me clicking on different items. It always prints "10", which is the last value that the album variable takes (there are 10 albums). Album: 0/Live on radio.electro-music.com Album: 1/Doodles Album: 2/Misc Stuff Album: 3/Drawer Collection Album: 4/Misc Electronic Stuff Album: 5/Odds & Ends Album: 6/Tumbler Album: 7/Bakelit 32 Album: 8/Film Album: 9/Bakelit Album: 10/Slow Zoom/Atomic Heart contents: 10 contents: 10 contents: 10 contents: 10 contents: 10 Any ideas? Driving me up the wall, this is. :) /Stefan

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  • jquery scope issue

    - by matthewb
    I am having issue with the following: I can't seem to keep the link I am selecting in each repeated item. The word "this" is getting lost. the Var event_id works for each element, but the var $something is undefined? Why is that, Ideally I wanted to do a switch statement but same issue, can't seem to get it to know what link I click and the elements around it to do the action. Updated Full Function: function rsvp (selector,function_url) { $(selector).livequery('click',function(){ var $select = $(selector).attr('rel'); var $event_id= $(this).parents('ul.event-options').attr('rel'); if ($select == "attending") { $(this).closest('span.rsvp-status').html("I'm Attending &ndash; <a href='javascript:;' class='remove' rel='remove'>Remove</a>"); var $something = $(this).parents('ul.event-options').attr('rel'); alert($something); } if ($select == "remove") { $(this).closest('span.rsvp-status').html("Not Attending &ndash; <a href='javascript:;' class='rsvp' rel='attending'>RSVP?</a>"); } if ($select == "interested") { $(this).closest('li').addClass('interested'); $(this).closest('li').removeClass('not-interested'); $(this).closest('li').html("You're Interested"); } $.ajax({ type: "POST", url: "/events/set_member/"+function_url, data: "event_id="+$event_id, beforeSend: function() { $("<span class='notice'>Updating...</span>").prependTo('body'); }, complete: function() { $('span.notice').fadeOut(500); } }); }); } rsvp ('a.rsvp','rsvp'); rsvp ('a.interests','interested'); rsvp ('a.remove','remove'); HTML <ul class="event-options" rel="<?=$event['event_id']?>"> <?php if($event['rsvp_total'] > 0) { ?> <!-- Show Only When Count is Greater than 0 --> <li class="group"><span class="total"><?= $event['rsvp_total']?></span>Interested </li> <?php } ?> <li class="rsvp"><span class="rsvp-status"> Not Attending &ndash; <a href="javascript:;" class="rsvp" rel="attending">RSVP?</a></span></li> <li class="not-interested"> <a href="javascript:;" class="interests" rel="interested"> Interested? </a> </li> <li class="place"><span><a href="<?=$place_path.$event['place_id']?>"><?=$event['place_name']?></a></span></li> <li class="share" rel="<?=$event['event_name']?>"> <a class="sharethis"></a> </li> </ul>

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  • Scope of "library" methods

    - by JS
    Hello, I'm apparently laboring under a poor understanding of Python scoping. Perhaps you can help. Background: I'm using the 'if name in "main"' construct to perform "self-tests" in my module(s). Each self test makes calls to the various public methods and prints their results for visual checking as I develop the modules. To keep things "purdy" and manageable, I've created a small method to simplify the testing of method calls: def pprint_vars(var_in): print("%s = '%s'" % (var_in, eval(var_in))) Calling pprint_vars with: pprint_vars('some_variable_name') prints: some_variable_name = 'foo' All fine and good. Problem statement: Not happy to just KISS, I had the brain-drizzle to move my handy-dandy 'pprint_vars' method into a separate file named 'debug_tools.py' and simply import 'debug_tools' whenever I wanted access to 'pprint_vars'. Here's where things fall apart. I would expect import debug_tools foo = bar debug_tools.pprint_vars('foo') to continue working its magic and print: foo = 'bar' Instead, it greets me with: NameError: name 'some_var' is not defined Irrational belief: I believed (apparently mistakenly) that import puts imported methods (more or less) "inline" with the code, and thus the variable scoping rules would remain similar to if the method were defined inline. Plea for help: Can someone please correct my (mis)understanding of scoping regards imports? Thanks, JS

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  • Rails Named Scope and overlapping conditions

    - by Tumtu
    Hi everyone, have a question about rails SQL generation: class Organization < ActiveRecord::Base has_many :people named_scope :active, :conditions => { :active => 'Yes' } end class Person < ActiveRecord::Base belongs_to :organization end Rails SQL for all active people in the first organiztion Organization.first.people.active.all [4;36;1mOrganization Load (0.0ms)[0m [0;1mSELECT TOP 1 * FROM [organizations] [0m [4;35;1mPerson Load (0.0ms)[0m [0mSELECT * FROM [people] WHERE ((([people].[active] = 'Yes') AND ([people].organization_id = 1)) AND ([people].organization_id = 1)) [0m Why Rails generates "[people].organization_id = 1" condition twice ? Does someone know how to make it DRY ? e.g. SELECT * FROM [people] WHERE (([people].[active] = 'Yes') AND ([people].organization_id = 1))

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  • PHP scope question

    - by Dan
    Hi, I'm trying to look through an array of records (staff members), in this loop, I call a function which returns another array of records (appointments for each staff member). foreach($staffmembers as $staffmember) { $staffmember['appointments'] = get_staffmember_appointments_for_day($staffmember); // print_r($staffmember['appointments'] works fine } This is working OK, however, later on in the script, I need to loop through the records again, this time making use of the appointment arrays, however they are unavailable. foreach ($staffmembers as $staffmember) { //do some other stuff //print_r($staffmember['appointments'] no longer does anything } Normally, I would perform the function from the first loop, within the second, however this loop is already nested within two others, which would cause the same sql query to be run 168 times. Can anyone suggest a workaround? Any advice would be greatly appreciated. Thanks

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  • Property Scope (Iphone)

    - by Hank
    Hello All. I am having trouble accessing a declared property and I think I am missing something fundamental about the nature of properties and perhaps view controllers. Here's what I'm doing so far: declaring a property "myPhone" in a root view controller called RootViewController. grabbing a phone number from a modally presented people picker setting "myPhone" to the value from the people picker (from within shouldContinueAfterSelectingPerson of ABPeoplePickerNavigationController) trying to access "myPhone" from another modally presented view controller "myPhone" continues to NSLog to null despite trying every permutation of self.myPhone, super, RootViewController, etc. to try and access the value I set. What am I missing?

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  • C pointer array scope and function calls

    - by juvenis
    I have this situation: { float foo[10]; for (int i = 0; i < 10; i++) { foo[i] = 1.0f; } object.function1(foo); // stores the float pointer to a const void* member of object } object.function2(); // uses the stored void pointer Are the contents of the float pointer unknown in the second function call? It seems that I get weird results when I run my program. But if I declare the float foo[10] to be const and initialize it in the declaration, I get correct results. Why is this happening?

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  • jQuery variables and scope

    - by Peuge
    I am writing a jQuery plugin and am running into a few problems with regard to variables. For example I have the following skeleton structure for my plugin, which is going to act on a textbox. In my init function I want to set a variable and bind a keypress event to my textbox. That keypress event needs to call another function, in which I need the variable. Is this possible? (function($){ var methods = { init : function(options){ return this.each(function(){ var $this = $(this); var someVar = 'somevar'; $this.keypress(function(event){ //I want to call my customFunction }); }); }, customFunction : function(){ //I am wanting to access 'someVar' here }; $.fn.mynamespace = function(method){ //handle which method to call here }; })(jQuery); Many thanks in advance.

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  • Javascript: Access the right scope "under" apply(...)

    - by Chau
    This is a very old problem, but I cannot seem to get my head around the other solutions presented here. I have an object function ObjA() { var a = 1; this.methodA = function() { alert(a); } } which is instantiated like var myObjA = new ObjA(); Later on, I assign my methodA as a handler function in an external Javascript Framework, which invokes it using the apply(...) method. When the external framework executes my methodA, this belongs to the framework function invoking my method. Since I cannot change how my method is called, how do I regain access to the private variable a? My research tells me, that closures might be what I'm looking for.

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  • How do I scope variables properly in jQuery?

    - by safetycopy
    I'm working on a jQuery plugin, but am having some trouble getting my variables properly scoped. Here's an example from my code: (function($) { $.fn.ksana = function(userOptions) { var o = $.extend({}, $.fn.ksana.defaultOptions, userOptions); return this.each(function() { alert(rotate()); // o is not defined }); }; function rotate() { return Math.round(o.negRot + (Math.random() * (o.posRot - o.negRot))); }; $.fn.ksana.defaultOptions = { negRot: -20, posRot: 20 }; })(jQuery); I'm trying to get the private function rotate to be able to see the o variable, but it just keeps alerting 'o is not defined'. I'm not sure what I'm doing wrong.

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  • Basic Python: Exception raising and local variable scope / binding

    - by SuperJdynamite
    I have a basic "best practices" Python question. I see that there are already StackOverflow answers tangentially related to this question but they're mired in complicated examples or involve multiple factors. Given this code: #!/usr/bin/python def test_function(): try: a = str(5) raise b = str(6) except: print b test_function() what is the best way to avoid the inevitable "UnboundLocalError: local variable 'b' referenced before assignment" that I'm going to get in the exception handler? Does python have an elegant way to handle this? If not, what about an inelegant way? In a complicated function I'd prefer to avoid testing the existence of every local variable before I, for example, printed debug information about them.

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  • Variable scope problem in JavaScript

    - by dfjhdfjhdf
    I declare a variable with the var word inside a function that handles Ajax requests, then later on in the function I have another function that should change the value of the variable but - my problem - it fails. How to settle the problem down? Here's similiar code I use: function sendRuest(someargums) { /* some code */ var the_variable; /* some code */ //here's that other function request.onreadystatechange = function() { if (request.readyState == 4) { switch (request.status) { case 200: //here the variable should be changed the_variable = request.responseXML; /* a lot of code */ //somewhere here the function closes } return the_variable; } var data = sendRequest(someargums); //and trying to read the data I get the undefined value

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  • Global JavaScript Variable Scope: Why doesn't this work?

    - by CoryDorning
    So I'm playing around with JavaScript and came across what I think to be an oddity. Is anyone able to explain the following? (i've included the alerted values as comments) Why is the first alert(msg) inside foo() returning undefined and not outside? var msg = 'outside'; function foo() { alert(msg); // undefined var msg = 'inside'; alert(msg); // inside } foo(); alert(msg); // outside Considering these both work fine: var msg = 'outside'; function foo() { alert(msg); // outside } alert(msg); // outside and: var msg = 'outside'; function foo() { var msg = 'inside'; alert(msg); // inside } alert(msg); // outside

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  • Accessing variables with different scope in C++

    - by Portablejim
    With #include <iostream> using namespace std; int a = 1; int main() { int a = 2; if(true) { int a = 3; cout << a << " " << ::a // Can I access a = 2 here? << " " << ::a << endl; } cout << a << " " << ::a << endl; } having the output 3 1 1 2 1 Is there a way to access the 'a' equal to 2 inside the if statement where there is the 'a' equal to 3, with the output 3 2 1 2 1 Note: I know this should not be done (and the code should not get to the point where I need to ask). This question is more "can it be done".

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  • Android Static Variable Scope and Lifetime

    - by Edison
    I have an application that has a Service uses a ArrayList to store in the background for a very long time, the variable is initialized when the service started. The service is in the background and there will be frequent access to the variable (that's why i don't want to use file management or settings since it will be very expensive for a file I/O for the sake of battery life). The variable will likely to be ~1MB-2MB over its life tie. Is it safe to say that it will never be nulled by GC or the system or is there any way to prevent it? Thanks.

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