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  • Question on overview of C# OOP in business WinForms application - scope of Object

    - by TimR
    I may have all this OO completely wrong, but here goes: Ok the scenario is a classic order entry. Customer places an Order which has OrderLineItems of StockItems. Order is entered by Employee. 1) Application starts and asks for login/password 2) Employee selects 'Orders' from Mainmenu form 3) Orders forms opens.... 4) Employee selects Customer 5) Employee selects Stock adds to OrderLineItems 6) Selects second StockItem; add to OrderLineItems 7) Order is committed, [stock decremented, order posted to DB, Order printed] 8) Employee is returned to MainMenu Now with Object scope: 1) Application starts and asks for login/password Is this the best place to make objEmployee, to be kept whilst in this whole Sales application? 2) Employee selects 'Orders' from Mainmenu form 3) Orders forms opens.... *Make objOrderHeader, is objEmployee able to be passed in or is it created here, or re-created here.* 4) Employee selects Customer - adds/edits Customer details if required... Make objCustomer 5) Employee selects Stock adds to OrderLineItems... *Make objStockItem and objOrderLineItem - add to objOrderLineItems_collection* 6) Selects second StockItem; add to OrderLineItems... *Make objStockItem and objOrderLineItem - add to objOrderLineItems_collection* 7) Order is committed, [stock decremented, order posted to DB, Order printed, Order Entered By = EmployeeID] Once posted to Db, all objects now redundant/garbage [except objEmployee?] 8) Employee is returned to MainMenu is objEmployee still valid as an object?

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  • MySQL to PostreSQL and Named Scope

    - by Lowgain
    I've got a named scope for one of my models that works fine. The code is: named_scope :inbox_threads, lambda { |user| { :include => [:deletion_flags, :recipiences], :conditions => ["recipiences.user_id = ? AND deletion_flags.user_id IS NULL", user.id], :group => "msg_threads.id" }} This works fine on my local copy of the app with a MySQL database, but when I push my app to Heroku (which only uses PostgreSQL), I get the following error: ActiveRecord::StatementInvalid (PGError: ERROR: column "msg_threads.subject" must appear in the GROUP BY clause or be used in an aggregate function: SELECT "msg_threads"."id" AS t0_r0, "msg_threads"."subject" AS t0_r1, "msg_threads"."originator_id" AS t0_r2, "msg_thr eads"."created_at" AS t0_r3, "msg_threads"."updated_at" AS t0_r4, "msg_threads"."url_key" AS t0_r5, "deletion_flags"."id" AS t1_r0, "deletion_flags"."user_id" AS t1_r1, "deletion_flags"."msg_thread_id" AS t1_r2, "deletion_flags"."confirmed" AS t1_r3, "deletion_flags"."created_at" AS t1_r4, "deletion_flags"."updated_at" AS t1_r5, "recipiences"."id" AS t2_r0, "recipiences"."user_id" AS t2_r1, "recipiences"."msg_thread_id" AS t2_r2, "recipiences"."created_at" AS t2_r3, "recipien ces"."updated_at" AS t2_r4 FROM "msg_threads" LEFT OUTER JOIN "deletion_flags" ON deletion_flags.msg_thread_id = msg_threads.id LEFT OUTER JOIN "recipiences" ON recipiences.msg_thread_id = msg_threads.id WHERE (recipiences.user_id = 1 AND deletion_flags.user_id IS NULL) GROUP BY msg_threads.id) I'm not as familiar with the working of Postgres, so what would I need to add here to get this working? Thanks!

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  • SQL - table alias scope.

    - by Support - multilanguage SO
    I've just learned ( yesterday ) to use "exists" instead of "in". BAD select * from table where nameid in ( select nameid from othertable where otherdesc = 'SomeDesc' ) GOOD select * from table t where exists ( select nameid from othertable o where t.nameid = o.nameid and otherdesc = 'SomeDesc' ) And I have some questions about this: 1) The explanation as I understood was: "The reason why this is better is because only the matching values will be returned instead of building a massive list of possible results". Does that mean that while the first subquery might return 900 results the second will return only 1 ( yes or no )? 2) In the past I have had the RDBMS complainin: "only the first 1000 rows might be retrieved", this second approach would solve that problem? 3) What is the scope of the alias in the second subquery?... does the alias only lives in the parenthesis? for example select * from table t where exists ( select nameid from othertable o where t.nameid = o.nameid and otherdesc = 'SomeDesc' ) AND select nameid from othertable o where t.nameid = o.nameid and otherdesc = 'SomeOtherDesc' ) That is, if I use the same alias ( o for table othertable ) In the second "exist" will it present any problem with the first exists? or are they totally independent? Is this something Oracle only related or it is valid for most RDBMS? Thanks a lot

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  • jQuery async ajax query and returning value problem (scope, closure)

    - by glebovgin
    Hi. Code not working because of async query and variable scope problem. I can't understand how to solve this. Change to $.ajax method with async:false - not an option. I know about closures, but how I can implement it here - don't know. I've seen all topics here about closures in js and jQuery async problems - but still nothing. Help, please. Here is the code: var map = null; var marker; var cluster = null; function refreshMap() { var markers = []; var markerImage = new google.maps.MarkerImage('/images/image-1_32_t.png', new google.maps.Size(32, 32)); $.get('/get_users.php',{},function(data){ if(data.status == 'error') return false; var users = data.users; // here users.length = 1 - this is ok; for(var i in users) { //here I have every values from users - ok var latLng = new google.maps.LatLng(users[i].lat, users[i].lng); var mark = new google.maps.Marker({ position: latLng, icon: markerImage }); markers.push(mark); alert(markers.length); // length 1 } },'json'); alert(markers.length); // length 0 //if I have alert() above - I get result cluster = new MarkerClusterer(map, markers, { maxZoom: null, gridSize: null }); } Thanks.

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  • Netbeans 7.2 Missing Modules Warning

    - by el10780
    Everytime I start Netbeans and the splash screen shows up when it gets to the part to load the modules I receive the following error message : Warning - could not install some modules: Editor Library 2 - None of the modules providing the capability org.netbeans.modules.editor.actions could be installed. Tags Based Editors Library - The module named org.netbeans.modules.editor.deprecated.pre65formatting/0-1 was needed and not found. Java Editor Library - The module named org.netbeans.modules.editor.deprecated.pre65formatting/0-1 was needed and not found. Preprocessor Bridge - None of the modules providing the capability org.netbeans.modules.java.preprocessorbridge.spi.JavaSourceUtilImpl could be installed. Freeform Ant Projects - The module named org.netbeans.modules.editor.indent.project/0-1 was needed and not found. Editor Code Templates - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. Static Analysis Core - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. Java Source - The module named org.netbeans.modules.editor.indent.project/0-1 was needed and not found. Eclipse Project Importer - The module named org.netbeans.modules.java.api.common/0-1 was needed and not found. Java Hints SPI - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. Java Refactoring - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. Java Editor - The module named org.netbeans.modules.editor.bracesmatching/0-1 was needed and not found. Java Editor - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. Java Editor - The module named org.netbeans.modules.editor.deprecated.pre65formatting/0-1 was needed and not found. Java Hints UI - The module named org.netbeans.modules.code.analysis/0-1 was needed and not found. Java Hints UI - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. Legacy Java Hints SPI - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. Java Hints - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. Java Declarative Hints - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. Javadoc - The module named org.netbeans.modules.editor.bracesmatching/0-1 was needed and not found. Javadoc - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. Common Scripting Language API (new) - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. XML Text Editor - The module named org.netbeans.modules.editor.bracesmatching/0-1 was needed and not found. XML Text Editor - The module named org.netbeans.modules.editor.deprecated.pre65formatting/0-1 was needed and not found. CSS Editor - The module named org.netbeans.modules.editor.bracesmatching/0-1 was needed and not found. HTML Editor - The module named org.netbeans.modules.editor.bracesmatching/0-1 was needed and not found. JavaScript Editing - The module named org.netbeans.modules.editor.bracesmatching/0-1 was needed and not found. JavaScript Hints - The module named org.netbeans.spi.editor.hints/0-1 was needed and not found. Editing Files - The module named org.netbeans.modules.editor.bracesmatching/0-1 was needed and not found. IDE Platform - The module named org.netbeans.modules.editor.macros/0-1 was needed and not found. Java SE Projects - The module named org.netbeans.modules.java.api.common/0-1 was needed and not found. 86 further modules could not be installed due to the above problems. Whatever I press either Exit or Disable Modules and Continue or even I close from the "X" Button the Warning window closes and then Netbeans never starts. I have looked it up on the Internet,but I couldn't find a solution.

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  • Create named criteria in EJB Data control

    - by shantala.sankeshwar
    This article gives the detailed steps on creating named criteria in EJB Data control.Note that this feature is available in Jdev version 11.1.2.0.0Use Case DescriptionSuppose we have defined an EJB Entity Object & we would like to filter the Entity object based on some criteria,then this filtering can be achieved by creating named criteria in EJB Data Control.Implementation stepsLet us suppose that we have created Java EE Web Application with Entities from Emp table Create session bean,generate data control for the same Edit empFindAll in DataControls.dcx fileCreate simple Named Criteria: deptno>=20Create on '+' icon to create Named Criteria:Refresh the Data Controls & create a new jspx page.Drop EmpCriteria as ADF Query Panel with TableRun the page,click on search button & we will see that Emp table shows filtered records

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  • EJB Named Criteria - Apply bind variable in Backingbean

    - by Deepak Siddappa
    EJB Named criteria are predefined and reusable where-clause definitions that are dynamically applied to a ViewObject query. Here we often use to filter the ViewObject SQL statement query based on Where Clause conditions.Take a scenario where we need to filter the SQL statements query based on Where Clause conditions, instead of playing with SQL statements use the EJB Named Criteria which is supported by default in ADF and set the Bind Variable parameter at run time.You can download the sample workspace from here [Runs with Oracle JDeveloper 11.1.2.0.0 (11g R2) + HR Schema] Implementation StepsCreate Java EE Web Application with entity based on Employees table, then create a session bean and data control for the session bean.Open the DataControls.dcx file and create sparse xml for as shown below. In sparse xml navigate to Named criteria tab -> Bind Variable section, create binding variable deptId. Now create a named criteria and map the query attributes to the bind variable. In the ViewController create index.jspx page, from data control palette drop employeesFindAll->Named Criteria->EmployeesCriteria->Table as ADF Read-Only Filtered Table and create the backingBean as "IndexBean".Open the index.jspx page and remove the "filterModel" binding from the table, add <af:inputText />, command button and bind them to backingBean. For command button create the actionListener as "applyEmpCriteria" and add below code to the file. public void applyEmpCriteria(ActionEvent actionEvent) { DCIteratorBinding dc = (DCIteratorBinding)evaluteEL("#{bindings.employeesFindAllIterator}"); ViewObject vo = dc.getViewObject(); vo.applyViewCriteria(vo.getViewCriteriaManager().getViewCriteria("EmployeesCriteria")); vo.ensureVariableManager().setVariableValue("deptId", this.getDeptId().getValue()); vo.executeQuery(); } /** * Programmtic evaluation of EL * * @param el EL to evalaute * @return Result of the evalutaion */ public Object evaluteEL(String el) { FacesContext fctx = FacesContext.getCurrentInstance(); ELContext elContext = fctx.getELContext(); Application app = fctx.getApplication(); ExpressionFactory expFactory = app.getExpressionFactory(); ValueExpression valExp = expFactory.createValueExpression(elContext, el, Object.class); return valExp.getValue(elContext); } Run the index.jspx page, enter departmentId value as 90 and click in ApplyEmpCriteria button. Now the bind variable for the Named criteria will be applied at runtime in the backing bean and it will re-execute ViewObject query to filter based on where clause condition.

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  • C# 4.0 Optional/Named Parameters Beginner&rsquo;s Tutorial

    - by mbcrump
    One of the interesting features of C# 4.0 is for both named and optional arguments.  They are often very useful together, but are quite actually two different things.  Optional arguments gives us the ability to omit arguments to method invocations. Named arguments allows us to specify the arguments by name instead of by position.  Code using the named parameters are often more readable than code relying on argument position.  These features were long overdue, especially in regards to COM interop. Below, I have included some examples to help you understand them more in depth. Please remember to target the .NET 4 Framework when trying these samples. Code Snippet using System;   namespace ConsoleApplication3 {     class Program     {         static void Main(string[] args)         {               //C# 4.0 Optional/Named Parameters Tutorial               Foo();                              //Prints to the console | Return Nothing 0             Foo("Print Something");             //Prints to the console | Print Something 0             Foo("Print Something", 1);          //Prints to the console | Print Something 1             Foo(x: "Print Something", i: 5);    //Prints to the console | Print Something 5             Foo(i: 5, x: "Print Something");    //Prints to the console | Print Something 5             Foo("Print Something", i: 5);       //Prints to the console | Print Something 5             Foo2(i3: 77);                       //Prints to the console | 77         //  Foo(x:"Print Something", 5);        //Positional parameters must come before named arguments. This will error out.             Console.Read();         }           static void Foo(string x = "Return Nothing", int i = 0)         {             Console.WriteLine(x + " " + i + Environment.NewLine);         }           static void Foo2(int i = 1, int i2 = 2, int i3 = 3, int i4 = 4)         {             Console.WriteLine(i3);         }     } }

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  • Using HtmlAnchor for anchor tag that navigates in-page named anchor

    - by Frank Schwieterman
    I am trying to render a simple hyperlink that links to a named anchor within the page, for example: <a href="#namedAnchor"scroll to down</a <a name="namedAnchor"down</a The problem is that when I use an ASP.NET control like asp:HyperLink or HtmlAnchor, the href="#namedAnchor" is rendered as href="controls/#namedAnchor" (where controls is the subdirectory where the user control containing the anchor is). Here is the code for the control, using two types of anchor controls, which both have the same problem: <%@ Control Language="C#" AutoEventWireup="true" CodeBehind="Test.ascx.cs" Inherits="TestWebApplication1.controls.Test" % <a href="#namedAnchor" runat="server"HtmlAnchor</a <asp:HyperLink NavigateUrl="#namedAnchor" runat="server"HyperLink</asp:HyperLink The generated source looks like: <a href="controls/#namedAnchor"HtmlAnchor</a <a href="controls/#namedAnchor"HyperLink</a I really just want: <a href="#namedAnchor"HtmlAnchor</a <a href="#namedAnchor"HyperLink</a I am using the HtmlAnchor or HyperLink class because I want to make changes to other attributes in the code behind. I do not want to introduce a custom web control for this requirement, as the requirement I'm pursuing is not that important and it would be hard to talk the team into abandoning the traditional ASP.NET link controls. It seems like I should be able to use the ASP.NET link controls to generate the desired link.

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  • Firefox reloading parent page in iframe when clicking named anchor

    - by masty
    My site has an iframe which is dynamically populated with html content. The html often contains named anchors, which work fine in IE/Chrome but in Firefox it reopens the entire page within the iframe. Here's an example: load the page in firefox, scroll to the bottom of the iframe, click the "back to top" link, and you will see what I am talking about. <html><head></head><body onload="setFrameContent();"><script> var htmlBody = '<html> <head></head> <body>' + '<a name="top"><h1>top</h1></a>' + '<br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/>' + '<br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/>' + '<a href="#top">back to top</a></body> </html> '; function setFrameContent(){ if (frames.length > 0) { var d = frames[0].document; d.open(); d.write(htmlBody); d.close(); } } </script> <h1>Here's an iframe:</h1> <iframe id="htmlIframe" style="height: 400px; width: 100%"><p>Your browser does not support iframes.</p></iframe> </body></html> Any ideas?

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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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  • Raphael Scope Drag n drop multiple paper instances

    - by donald
    I have two Raphael paper instances. In both I want to drag and drop an element (circle). It is important for me to assign both these circles the same id. I expected no problem, as both are in different paper instances and therefore in different scope. What happens is, that somehow both elements react, when I have clicked both elements at least once. If I however give these elements different IDs everything works fine (each element only calls its "start", "drag" and "up" function if draged around). Is this intended behaviour of Raphael and do I have to assign different IDs to the elements in the different paper instances? Hopefully not and you can point me to the right direction :-) Thanks a lot for your Help in advance, Here comes the code: <!doctype html> <html> <head> <meta charset="utf-8" /> <title>DragNDrop</title> <script src="raphael-min.js"></script> </head> <body> <h1>Paper1</h1> <div id="divPaper1" style ="height: 150px; width: 300px; border:thin solid red"></div> <h1>Paper2</h1> <div id="divPaper2" style ="height: 150px; width: 300px; border:thin solid red"></div> <script> start1 = function () { console.log("start1"); } drag1 = function () { console.log("move1"); } up1 = function () { console.log("up1"); } start2 = function () { console.log("start2"); } drag2 = function () { console.log("move2"); } up2 = function () { console.log("up2"); } var paper1 = Raphael("divPaper1", "100%", "100%"); var circle1 = paper1.circle(40, 40, 30); circle1.attr("fill", "yellow"); circle1.id = "circle"; //both circles get the same id circle1.drag(drag1, start1, up1); paper2 = Raphael("divPaper2", "100%", "100%"); var circle2 = paper2.circle(40, 40, 30); circle2.attr("fill", "red"); circle2.id = "circle"; //both circles get the same id circle2.drag(drag2, start2, up2); </script> </body>

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  • How can I determine which named property (or properties) are filling my exchange 2007 information st

    - by Mikey B
    Hi Guys, I'm experiencing the following error on an Exchange 2007 server: Event ID: 9667 Type: Error Category: General Source: msgidNamedPropsQuotaError Description: Failed to create a new named property for database "" because the number of named properties reached the quota limit (). User attempting to create the named property: . Named property GUID: . Named property name/id: . I understand that this can occur if the exchange information store is filling up with named properties... but I don't know how to determine which specific named property is at fault here. Is there a way to examine the DB for this type of info to see if there's a specific recurring named property that is consuming resources? -M

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  • named responding recursive on norecurse queries

    - by Keks
    I have a server on which named is running. It is intercepted with another named server which it is not aware of. Querying the first named server results in timeouts. The server tries to resolve the query recursively. During that the firewall redirects the DNS Request from the first named server to the second one (the query from the first one is addressed to a e.g. a root server and has its "Recursion desired" bit set to 0). Despite that the second named responds to this request with a entirely or at least 1 level more resolved response than the first named server expects. So it ends up with a timeout even though it got a correct name server or even the full IP for the queried domain. In the first case the first name server tries to follow the authority domain ignoring the coresponding glue record and ends up in a loop it aborts: queried: google.com -> got from named#2: ns1.google.com -> ignore glue record and query: ns1.google.com -> got authority from named#2: google.com In the second case it ignores the answer section with the correct IP and instead tries to follow the name servers from the authority section, which ends up in the same dead end as case 1. So how can it be that the second named responds with recursive results even though the bit was explicitly set to 0 in the request from the first named?

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  • C++: Implementing Named Pipes using the Win32 API

    - by Mike Pateras
    I'm trying to implement named pipes in C++, but either my reader isn't reading anything, or my writer isn't writing anything (or both). Here's my reader: int main() { HANDLE pipe = CreateFile(GetPipeName(), GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL); char data[1024]; DWORD numRead = 1; while (numRead >= 0) { ReadFile(pipe, data, 1024, &numRead, NULL); if (numRead > 0) cout << data; } return 0; } LPCWSTR GetPipeName() { return L"\\\\.\\pipe\\LogPipe"; } And here's my writer: int main() { HANDLE pipe = CreateFile(GetPipeName(), GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL); string message = "Hi"; WriteFile(pipe, message.c_str(), message.length() + 1, NULL, NULL); return 0; } LPCWSTR GetPipeName() { return L"\\\\.\\pipe\\LogPipe"; } Does that look right? numRead in the reader is always 0, for some reason, and it reads nothing but 1024 -54's (some weird I character). Solution: Reader (Server): while (true) { HANDLE pipe = CreateNamedPipe(GetPipeName(), PIPE_ACCESS_INBOUND | PIPE_ACCESS_OUTBOUND , PIPE_WAIT, 1, 1024, 1024, 120 * 1000, NULL); if (pipe == INVALID_HANDLE_VALUE) { cout << "Error: " << GetLastError(); } char data[1024]; DWORD numRead; ConnectNamedPipe(pipe, NULL); ReadFile(pipe, data, 1024, &numRead, NULL); if (numRead > 0) cout << data << endl; CloseHandle(pipe); } Writer (client): HANDLE pipe = CreateFile(GetPipeName(), GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL); if (pipe == INVALID_HANDLE_VALUE) { cout << "Error: " << GetLastError(); } string message = "Hi"; cout << message.length(); DWORD numWritten; WriteFile(pipe, message.c_str(), message.length(), &numWritten, NULL); return 0; The server blocks until it gets a connected client, reads what the client writes, and then sets itself up for a new connection, ad infinitum. Thanks for the help, all!

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  • Help needed with Javascript Variable Scope / OOP and Call Back Functions

    - by gargantaun
    I think this issue goes beyond typical variable scope and closure stuff, or maybe I'm an idiot. Here goes anyway... I'm creating a bunch of objects on the fly in a jQuery plugin. The object look something like this function WedgePath(canvas){ this.targetCanvas = canvas; this.label; this.logLabel = function(){ console.log(this.label) } } the jQuery plugin looks something like this (function($) { $.fn.myPlugin = function() { return $(this).each(function() { // Create Wedge Objects for(var i = 1; i <= 30; i++){ var newWedge = new WedgePath(canvas); newWedge.label = "my_wedge_"+i; globalFunction(i, newWedge]); } }); } })(jQuery); So... the plugin creates a bunch of wedgeObjects, then calls 'globalFunction' for each one, passing in the latest WedgePath instance. Global function looks like this. function globalFunction(indicator_id, pWedge){ var targetWedge = pWedge; targetWedge.logLabel(); } What happens next is that the console logs each wedges label correctly. However, I need a bit more complexity inside globalFunction. So it actually looks like this... function globalFunction(indicator_id, pWedge){ var targetWedge = pWedge; someSql = "SELECT * FROM myTable WHERE id = ?"; dbInterface.executeSql(someSql, [indicator_id], function(transaction, result){ targetWedge.logLabel(); }) } There's a lot going on here so i'll explain. I'm using client side database storage (WebSQL i call it). 'dbInterface' an instance of a simple javascript object I created which handles the basics of interacting with a client side database [shown at the end of this question]. the executeSql method takes up to 4 arguments The SQL String an optional arguments array an optional onSuccess handler an optional onError handler (not used in this example) What I need to happen is: When the WebSQL query has completed, it takes some of that data and manipulates some attribute of a particular wedge. But, when I call 'logLabel' on an instance of WedgePath inside the onSuccess handler, I get the label of the very last instance of WedgePath that was created way back in the plugin code. Now I suspect that the problem lies in the var newWedge = new WedgePath(canvas); line. So I tried pushing each newWedge into an array, which I thought would prevent that line from replacing or overwriting the WedgePath instance at every iteration... wedgeArray = []; // Inside the plugin... for(var i = 1; i <= 30; i++){ var newWedge = new WedgePath(canvas); newWedge.label = "my_wedge_"+i; wedgeArray.push(newWedge); } for(var i = 0; i < wedgeArray.length; i++){ wedgeArray[i].logLabel() } But again, I get the last instance of WedgePath to be created. This is driving me nuts. I apologise for the length of the question but I wanted to be as clear as possible. END ============================================================== Also, here's the code for dbInterface object should it be relevant. function DatabaseInterface(db){ var DB = db; this.sql = function(sql, arr, pSuccessHandler, pErrorHandler){ successHandler = (pSuccessHandler) ? pSuccessHandler : this.defaultSuccessHandler; errorHandler = (pErrorHandler) ? pErrorHandler : this.defaultErrorHandler; DB.transaction(function(tx){ if(!arr || arr.length == 0){ tx.executeSql(sql, [], successHandler, errorHandler); }else{ tx.executeSql(sql,arr, successHandler, errorHandler) } }); } // ---------------------------------------------------------------- // A Default Error Handler // ---------------------------------------------------------------- this.defaultErrorHandler = function(transaction, error){ // error.message is a human-readable string. // error.code is a numeric error code console.log('WebSQL Error: '+error.message+' (Code '+error.code+')'); // Handle errors here var we_think_this_error_is_fatal = true; if (we_think_this_error_is_fatal) return true; return false; } // ---------------------------------------------------------------- // A Default Success Handler // This doesn't do anything except log a success message // ---------------------------------------------------------------- this.defaultSuccessHandler = function(transaction, results) { console.log("WebSQL Success. Default success handler. No action taken."); } }

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  • In Javascript, a function starts a new scope, but we have to be careful that the function must be in

    - by Jian Lin
    In Javascript, I am sometimes too immerged in the idea that a function creates a new scope, that sometimes I even think the following anonymous function will create a new scope when it is being defined and assigned to onclick: <a href="#" id="link1">ha link 1</a> <a href="#" id="link2">ha link 2</a> <a href="#" id="link3">ha link 3</a> <a href="#" id="link4">ha link 4</a> <a href="#" id="link5">ha link 5</a> <script type="text/javascript"> for (i = 1; i <= 5; i++) { document.getElementById('link' + i).onclick = function() { var x = i; alert(x); return false; } } </script> but in fact, the anonymous function will create a new scope, that's right, but ONLY when it is being invoked, is that so? So the x inside the anonymous function is not created, no new scope is created. When the function was later invoked, there is a new scope alright, but the i is in the outside scope, and the x gets its value, and it is all 6 anyways. The following code will actually invoke a function and create a new scope and that's why the x is a new local variable x in the brand new scope each time, and the invocation of the function when the link is clicked on will use the different x in the different scopes. <a href="#" id="link1">ha link 1</a> <a href="#" id="link2">ha link 2</a> <a href="#" id="link3">ha link 3</a> <a href="#" id="link4">ha link 4</a> <a href="#" id="link5">ha link 5</a> <script type="text/javascript"> for (var i = 1; i <= 5; i++) { (function() { var x = i; document.getElementById('link' + i).onclick = function() { alert(x); return false; } })(); // invoking it now! } </script> If we take away the var in front of x, then it is a global x and so no local variable x is created in the new scope, and therefore, clicking on the links get all the same number, which is the value of the global x.

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  • Templates, interfaces (multiple inheritance) and static functions (named constructors)

    - by fledgling Cxx user
    Setup I have a graph library where I am trying to decompose things as much as possible, and the cleanest way to describe it that I found is the following: there is a vanilla type node implementing only a list of edges: class node { public: int* edges; int edge_count; }; Then, I would like to be able to add interfaces to this whole mix, like so: template <class T> class node_weight { public: T weight; }; template <class T> class node_position { public: T x; T y; }; and so on. Then, the actual graph class comes in, which is templated on the actual type of node: template <class node_T> class graph { protected: node_T* nodes; public: static graph cartesian(int n, int m) { graph r; r.nodes = new node_T[n * m]; return r; } }; The twist is that it has named constructors which construct some special graphs, like a Cartesian lattice. In this case, I would like to be able to add some extra information into the graph, depending on what interfaces are implemented by node_T. What would be the best way to accomplish this? Possible solution I thought of the following humble solution, through dynamic_cast<>: template <class node_T, class weight_T, class position_T> class graph { protected: node_T* nodes; public: static graph cartesian(int n, int m) { graph r; r.nodes = new node_T[n * m]; if (dynamic_cast<node_weight<weight_T>>(r.nodes[0]) != nullptr) { // do stuff knowing you can add weights } if (dynamic_cast<node_position<positionT>>(r.nodes[0]) != nullptr) { // do stuff knowing you can set position } return r; } }; which would operate on node_T being the following: template <class weight_T, class position_T> class node_weight_position : public node, public node_weight<weight_T>, public node_position<position_T> { // ... }; Questions Is this -- philosophically -- the right way to go? I know people don't look nicely at multiple inheritance, though with "interfaces" like these it should all be fine. There are unfortunately problems with this. From what I know at least, dynamic_cast<> involves quite a bit of run-time overhead. Hence, I run into a problem with what I had solved earlier: writing graph algorithms that require weights independently of whether the actual node_T class has weights or not. The solution with this 'interface' approach would be to write a function: template <class node_T, class weight_T> inline weight_T get_weight(node_T const & n) { if (dynamic_cast<node_weight<weight_T>>(n) != nullptr) { return dynamic_cast<node_weight<weight_T>>(n).weight; } return T(1); } but the issue with it is that it works using run-time information (dynamic_cast), yet in principle I would like to decide it at compile-time and thus make the code more efficient. If there is a different solution that would solve both problems, especially a cleaner and better one than what I have, I would love to hear about it!

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  • Inherit one instance variable from the global scope

    - by Julian
    I'm using Curses to create a command line GUI with Ruby. Everything's going well, but I have hit a slight snag. I don't think Curses knowledge (esoteric to be fair) is required to answer this question, just Ruby concepts such as objects and inheritance. I'm going to explain my problem now, but if I'm banging on, just look at the example below. Basically, every Window instance needs to have .close called on it in order to close it. Some Window instances have other Windows associated with it. When closing a Window instance, I want to be able to close all of the other Window instances associated with it at the same time. Because associated Windows are generated in a logical fashion, (I append the name with a number: instance_variable_set(self + integer, Window.new(10,10,10,10)) ), it's easy to target generated windows, because methods can anticipate what assosiated windows will be called, (I can recreate the instance variable name from scratch, and almost query it: instance_variable_get(self + integer). I have a delete method that handles this. If the delete method is just a normal, global method (called like this: delete_window(@win543) then everything works perfectly. However, if the delete method is an instance method, which it needs to be in-order to use the self keyword, it doesn't work for a very clear reason; it can 'query' the correct instance variable perfectly well (instance_variable_get(self + integer)), however, because it's an instance method, the global instances aren't scoped to it! Now, one way around this would obviously be to simply make a global method like this: delete_window(@win543). But I have attributes associated with my window instances, and it all works very elegantly. This is very simplified, but it literally translates the problem exactly: class Dog def speak woof end end def woof if @dog_generic == nil puts "@dog_generic isn't scoped when .woof is called from a class method!\n" else puts "@dog_generic is scoped when .woof is called from the global scope. See:\n" + @dog_generic end end @dog_generic = "Woof!" lassie = Dog.new lassie.speak #=> @dog_generic isn't scoped when .woof is called from an instance method!\n woof #=> @dog_generic is scoped when .woof is called from the global scope. See:\nWoof! TL/DR: I need lassie.speak to return this string: "@dog_generic is scoped when .woof is called from the global scope. See:\nWoof!" @dog_generic must remain as an insance variable. The use of Globals or Constants is not acceptable. Could woof inherit from the Global scope? Maybe some sort of keyword: def woof < global # This 'code' is just to conceptualise what I want to do, don't take offence! end Is there some way the .woof method could 'pull in' @dog_generic from the global scope? Will @dog_generic have to be passed in as a parameter?

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  • Red Dot Scope Makes Sighting In Long Lenses a Snap

    - by Jason Fitzpatrick
    If you’ve ever used a high power lens, you know how tricky it can be to sight a distant subject as the field of view through the lens is so tiny. This hack takes care of that problem by using a zero-magnification red dot rifle scope. Chris Malcolm enjoys photographing birds and other wildlife with high power lenses. The problem, when shooting with huge 500mm lens and other high power lenses, is that they’re practically telescopes and acquiring a fast moving target like a bird using a through-the-lens technique is very tricky. Malcolm’s solution hinges on mounting a zero-magnification red dot rifle scope in parallel with the lens. His mock up is a bit unpolished (although we can understand not wanting to run out and buy a brand new black scope just for the experiment) but works great to get him on target. Hit up the link below to read more about his build, how be created the rail mount for the scope, and why he opted to mount it to the barrel of the lens and not the hot shoe mount on the camera. 500mm Reflex Lens with Red Dot Sight [via DIY Photography] Make Your Own Windows 8 Start Button with Zero Memory Usage Reader Request: How To Repair Blurry Photos HTG Explains: What Can You Find in an Email Header?

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  • How do you create a non-Thread-based Guice custom Scope?

    - by Russ
    It seems that all Guice's out-of-the-box Scope implementations are inherently Thread-based (or ignore Threads entirely): Scopes.SINGLETON and Scopes.NO_SCOPE ignore Threads and are the edge cases: global scope and no scope. ServletScopes.REQUEST and ServletScopes.SESSION ultimately depend on retrieving scoped objects from a ThreadLocal<Context>. The retrieved Context holds a reference to the HttpServletRequest that holds a reference to the scoped objects stored as named attributes (where name is derived from com.google.inject.Key). Class SimpleScope from the custom scope Guice wiki also provides a per-Thread implementation using a ThreadLocal<Map<Key<?>, Object>> member variable. With that preamble, my question is this: how does one go about creating a non-Thread-based Scope? It seems that something that I can use to look up a Map<Key<?>, Object> is missing, as the only things passed in to Scope.scope() are a Key<T> and a Provider<T>. Thanks in advance for your time.

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  • php variable scope in oop

    - by mr o
    Hi, I wonder if anyone can help out here, I'm trying to understand how use an objects properties across multiple non class pages,but I can't seem to be able to get my head around everything i have tried so far. For example a class called person; class person { static $name; } but i have a number of different regular pages that want to utilize $name across the board. I have trying things like this; pageone.php include "person.php"; $names = new Person(); echo person::$name; names::$name='bob'; pagetwo.php include "person.php"; echo person::$name; I can work with classes to the extent I'm OK as long as I am creating new instances every page, but how can make the properties of one object available to all, like a shared variable ? Thanks

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  • python variable scope

    - by Oscar Reyes
    I'm teaching my self python and I was translating some sample class Student: def __init__( self, name, a,b,c ): self.name = name self.a = a self.b = b self.c = c def average(self): return ( a+b+c ) / 3.0 Which is pretty much my intended class definition Later in the main method I create an instance and call it a if __name__ == "__main__" : a = Student( "Oscar", 10, 10, 10 ) That's how I find out that the variable a declared in main is available to the method average and that to make that method work , I have to type self.a + self.b + self.c instead What's the rationale of this? I found related questions, but I don't really know if they are about the same

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  • Google's 'go' and scope/functions

    - by danwoods
    In one of the example servers given at golang.org: package main import ( "flag" "http" "io" "log" "template" ) var addr = flag.String("addr", ":1718", "http service address") // Q=17, R=18 var fmap = template.FormatterMap{ "html": template.HTMLFormatter, "url+html": UrlHtmlFormatter, } var templ = template.MustParse(templateStr, fmap) func main() { flag.Parse() http.Handle("/", http.HandlerFunc(QR)) err := http.ListenAndServe(*addr, nil) if err != nil { log.Exit("ListenAndServe:", err) } } func QR(c *http.Conn, req *http.Request) { templ.Execute(req.FormValue("s"), c) } func UrlHtmlFormatter(w io.Writer, v interface{}, fmt string) { template.HTMLEscape(w, []byte(http.URLEscape(v.(string)))) } const templateStr = ` <html> <head> <title>QR Link Generator</title> </head> <body> {.section @} <img src="http://chart.apis.google.com/chart?chs=300x300&cht=qr&choe=UTF- 8&chl={@|url+html}" /> <br> {@|html} <br> <br> {.end} <form action="/" name=f method="GET"><input maxLength=1024 size=70 name=s value="" title="Text to QR Encode"><input type=submit value="Show QR" name=qr> </form> </body> </html> ` Why is template.HTMLEscape(w, []byte(http.URLEscape(v.(string)))) contained within UrlHtmlFormatter? Why can't it be directly linked to "url+html"?

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