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• How safe am I singing into Google Spreadsheets with yeroon.net/ggplot2

  - by Farrel

  I am impressed by what I have seen of yeroon.net/ggplot2 which is a web interface for Hadley Wickham's R package ggplot2. I want to try it out on my own data. The part that has me very excited is that one can use data stored in one's own Google spreadsheet as the data. One just signs into their Google Account so that yeroon.net/ggplot2 can access the spreadsheet list. I have been hesitant to do it. If I sign in whilst on yeroon.net am I handing over my username and password to a third party? It would not be wise of me to divulge my google password to third parties since Google is fast becoming my repository of everything. How do I know if Jeroon's application is using ClientLogin or OAuth? My understanding is very basic and may be wrong but nevertheless here it is. OAuth would be better since it does not actually pass the password onto the third party application.

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• Strange thing about .NET 4.0 filesystem enumeratation functionality

  - by codymanix

  I just read a page of "Whats new .NET Framework 4.0". I have trouble understanding the last paragraph: To remove open handles on enumerated directories or files Create a custom method (or function in Visual Basic) to contain your enumeration code. Apply the MethodImplAttribute attribute with the NoInlining option to the new method. For example: [MethodImplAttribute(MethodImplOptions.NoInlining)] Private void Enumerate() Include the following method calls, to run after your enumeration code: * The GC.Collect() method (no parameters). * The GC.WaitForPendingFinalizers() method. Why the attribute NoInlining? What harm would inlining do here? Why call the garbage collector manually, why not making the enumerator implement IDisposable in the first place? I suspect they use FindFirstFile()/FindNextFile() API calls for the imlementation, so FindClose() has to be called in any case if the enumeration is done.

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• Protected Members of Other Instances in Scala

  - by Masterofpsi

  I just ran into a difficulty while learning Scala. I have an inheritance hierarchy that is essentially equivalent to this: class A { protected def myMethod() = println("myMethod() from A") } class B extends A { def invokeMyMethod(a: A) = a.myMethod() } But trying to compile this sample, I get the error "test.scala:7: error: method myMethod cannot be accessed in A". Coming from Java, my understanding is that protected members should be accessible at any point from a derived class, and nowhere have I seen anything that tells me that protected members in Scala are limited by instance. Does anyone have an explanation for this?

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• Covariance and Contravariance on the same type argument

  - by William Edmondson

  The C# spec states that an argument type cannot be both covariant and contravariant at the same time. This is apparent when creating a covariant or contravariant interface you decorate your type parameters with "out" or "in" respectively. There is not option that allows both at the same time ("outin"). Is this limitation simply a language specific constraint or are there deeper, more fundamental reasons based in category theory that would make you not want your type to be both covariant and contravariant? Edit: My understanding was that arrays were actually both covariant and contravariant. public class Pet{} public class Cat : Pet{} public class Siamese : Cat{} Cat[] cats = new Cat[10]; Pet[] pets = new Pet[10]; Siamese[] siameseCats = new Siamese[10]; //Cat array is covariant pets = cats; //Cat array is also contravariant since it accepts conversions from wider types cats = siameseCats;

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• Studying MySQL, SQLite source code to learn about RDBMS implementation

  - by Yang

  I know implementing database is a huge topic, but I want to have a basic understanding of how database systems work (e.g. memory management, binary tree, transaction, sql parsing, multi-threading, partitions, etc) by investigating the source code of the database. Since there are a few already proven very robust open source databases like mysql, sqlite and so on. However, the code are very complicated and I have no clue where to start. Also I find that the old school database textbooks are only explaining the theory, not the implementation details. Can anyone suggest how I should get started and if there are any books that emphasis on the technology and techniques of building dbms used in modern database industry?

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• Strange problem with MySQL full text query

  - by Manish

  This probably has something to do with my understanding of full text search or perhaps a known issue. My Java code creates search term for full text search on MySQL like this - +word* This works fine if the value in the DB column contains more text than the word itself. However, if the value is exact - no result are returned. I expected it to return results when value is an exact match. Let me give an example - Assume that DB has column name with value "Manish", now if I search with this - +Manis* It does return the result correctly, but if I try this - +Manish* It doesn't return any result, though exact match exists in DB column - Name. How can I obtain the desired behaviour in both these cases? Removing + sign works, but it returns far too many results when there are two or more words. Any help, pointers would be highly appreciated! I am using MySQL 5.0 TIA, - Manish

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• Having trouble with binding

  - by Tam

  I'm not sure if I'm misunderstanding the binding in Flex. I'm using Cairngorm framework. I have the following component with code like: [Bindable] var _model:LalModelLocator = LalModelLocator.getInstance(); .... <s:DataGroup dataProvider="{_model.friendsSearchResults}" includeIn="find" itemRenderer="com.lal.renderers.SingleFriendDisplayRenderer"> <s:layout> <s:TileLayout orientation="columns" requestedColumnCount="2" /> </s:layout> </s:DataGroup> in the model locator: [Bindable] public var friendsSearchResults:ArrayCollection = new ArrayCollection(); Inside the item renderer there is a button that calls a command and inside the command results there is a line like this: model.friendsSearchResults = friendsSearchResults; Putting break points and stepping through the code I confirmed that this like gets called and the friendsSearchResults gets updated. To my understanding if I update a bindable variable it should automatically re-render the s:DataGroup which has a dataProvider of that variable.

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• Reverse engineering to get answers

  - by cornjuliox

  So I've spent the last few days looking for a way to create a simple image drawing app with wxPython, and I think the key to doing just that is understanding how to use Device Contexts. The problem is that the wxPython demo program doesn't demonstrate DCs, and the docs for both wxPython and wxWidgets don't explain as much as I'd like to know so I've decided to try and 'reverse engineer' an existing app to see how its done. The first problem I have is that I don't know of any drawing apps written in wxPython (or any written in Python for that matter o.o), and the second is I don't know how I'd go about doing it. Am I right in saying that I'm going to need a copy of an application's Python source and something like Winpdb? What do professional programmers do when they find themselves in a situation like mine, needing answers that the docs don't provide?

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• TCP-Connection Establishment = How to measure time based on Ping RRT?

  - by Tom

  Hello Experts, I would be greatful for help, understanding how long it takes to establish a TCP connection when I have the Ping RoundTripTip: According to Wikipedia a TCP Connection will be established in three steps: 1.SYN-SENT (=>CLIENT TO SERVER) 2.SYN/ACK-RECEIVED (=>SERVER TO CLIENT) 3.ACK-SENT (=>CLIENT TO SERVER) My Questions: Is it correct, that the third transmission (ACK-SENT) will not yet carry any payload (my data) but is only used for the connection establishement.(This leads to the conclusion, that the fourth packt will be the first packt to hold any payload....) Is it correct to assume, that when my Ping RoundTripTime is 20 milliseconds, that in the example given above, the TCP Connection establishment would at least require 30 millisecons, before any data can be transmitted between the Client and Server? Thank you very much Tom

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• fire and forget compared to http request

  - by cometta

  Hi, i looking for opinion from you all. I have a web application that need to records data into another web application database. I not prefer to use http request GET on 2nd application because of latency issue. I looking for fast way to save records on 2nd application quickly, i came across the idea of "fire and forget" , will JMX suit for this scenario? from my understanding jmx will gurantee message delivery. Let say i need to call at least 1000 random requests per seconds to 2nd application should i use jmx? http request? or xmpp instead?

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• 503 (Server Unavailable) WebException when loading local XHTML file in Visual C# 2008

  - by kcoppock

  Hello! So I'm currently working on an ePub reader application, and I've been reading through a bunch of regular XML files just fine with System.Xml and XmlDocument: XmlDocument xmldoc = new XmlDocument(); xmldoc.Load(Path.Combine(Directory.GetCurrentDirectory(), "META-INF/container.xml")); XmlNodeList xnl = xmldoc.GetElementsByTagName("rootfile"); However, now I'm trying to open the XHTML files that contain the actual book text, and they're XHTML files. Now I don't really know the difference between the two, but I'm getting the following error with this code (in the same document, using the same XmlDocument and XmlNodeList variable) xmldoc.Load(Path.Combine(Directory.GetCurrentDirectory(), "OEBPS/part1.xhtml")); "WebException was unhandled: The remote server returned an error: (503) Server Unavailable" It's a local document, so I'm not understanding why it's giving this error? Any help would be greatly appreciated. :) I've got the full source code here if it helps: http://drop.io/epubtest (I know the ePubConstructor.ParseDocument() method is horribly messy, I'm just trying to get it working at the moment before I split it into classes)

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• Language/tech specific books which improve vendor-neutral development skills

  - by dotnetdev

  If I ask what the following books have in common: "Accelerated C# 2010, C# in Depth, Pro C# 2008", the answer would be that they would help me to improve my understanding of C# and secondly, my general coding skills. What language-specific/tech-specific books (like those named above) would teach me a great deal about general programming techniques and good habits? I'm thinking Java books would be very good for me (I code in C# primarily), as both these languages are similar and so I am sure that specialist books on Java threading, performance tuning, etc, can be applied to C# (not all 100% content of a Java book). Thanks

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• Assignment in python for loop possible?

  - by flyingcrab

  I have a dictionary d (and a seperate sorted list of keys, keys). I wanted the loop to only process entries where the value is False - so i tried the following: for key in keys and not d[key]: #do foo I suppose my understanding of python sytax is not what i thought it was - because the assignment doesnt suppose to have happened above, and a i get an instanciation error. The below works of course, but I'd really like to be able to use something like the code above.. possible? for key in keys: if d[key]: continue #foo time! Thanks!

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• Integrate Jasper in Rails 3

  - by AndreDurao

  I'm trying to integrate a rails 3 app with jasper following this wiki: http://wiki.rubyonrails.org/rails/pages/HowtoIntegrateJasperReports But it seems that a lot of information isn't updated so it's been very hard to make it work by myself. I've also read a topic at ruby-forum: http://www.ruby-forum.com/topic/139453 with some details explained but still couldn't make it work. My first problem is related with the render_to_string method: When the controller method runs I receive a "Template is missing" error: this is the method: def report @customers = Customer.all send_doc(render_to_string(:template => report_customers_path, :layout => false), '/pdfs', 'report.jasper', "customers", 'pdf') end Although this seems simple I'm not understanding why is this happening. Doesn't render_to_string with layout = false suposed to get me the string result of that action? I also tried :action instead of :template, but it does the same. If anybody with some expertise with this integration could help... Thanks in advance, André

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• teaching my self Z/OS assembler?

  - by Jared

  'I've interned at a company that does a lot of mainframe work. Most of my mainframe experience has been using Java and Unix System Services. I've had some experience with the ISPF interface and C but none with assembler. I’m graduating shortly and will be taking an independent study my last semester. I’d like to stick with the mainframe and was wondering what resources could teach me mainframe assembler? Note I don’t have experience writing assembler for any platform but do understand binary, hex, and have a theoretical understanding of registers.

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• fourier transform to transpose key of a wav file

  - by tbischel

  I want to write an app to transpose the key a wav file plays in (for fun, I know there are apps that already do this)... my main understanding of how this might be accomplished is to 1) chop the audio file into very small blocks (say 1/10 a second) 2) run an FFT on each block 3) phase shift the frequency space up or down depending on what key I want 4) use an inverse FFT to return each block to the time domain 5) glue all the blocks together But now I'm wondering if the transformed blocks would no longer be continuous when I try to glue them back together. Are there ideas how I should do this to guarantee continuity, or am I just worrying about nothing?

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• How to write the Visitor Pattern for Abstract Syntax Tree in Python?

  - by bodacydo

  My collegue suggested me to write a visitor pattern to navigate the AST. Can anyone tell me more how would I start writing it? As far as I understand, each Node in AST would have visit() method (?) that would somehow get called (from where?). That about concludes my understanding. To simplify everything, suppose I have nodes Root, Expression, Number, Op and the tree looks like this: Root | Op(+) / \ / \ Number(5) \ Op(*) / \ / \ / \ Number(2) Number(444) Can anyone think of how the visitor pattern would visit this tree to produce output: 5 + 2 * 444 Thanks, Boda Cydo.

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• Classes / instances in Ontology

  - by SODA

  Hi, I'm trying to comprehend ontology basics. Here's an example: car (class) 2009 VW CC (sub-class or instance?) My neighbor's 2009 VW CC (instance) My issue is understanding what is "2009 VW CC" (as a car model). If you're making product model a sub-class in the ontology - all of a sudden your ontology becomes bloated with thousands of subclasses of a "car". That's redundant. At the same time we can't say "2009 VW CC" is an instance, at least it's not material instance of a class. Does it make sense to distinguish between regular instances and material (distinct physical objects)? At the other hand, if both are instances (of different nature so to say), then how can instance inherit properties / relations of a non-class?

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• Python's FTPLib too slow ?

  - by PyNEwbie

  I have been playing around with Python's FTP library and am starting to think that it is too slow as compared to using a script file in DOS? I run sessions where I download thousands of data files (I think I have over 8 million right now). My observation is that the download process seems to take five to ten times as long in Python than it does as compared to using the ftp commands in the DOS shell. Since I don't want anyone to fix my code I have not included any. I am more interested in understanding if my observation is valid or if I need to tinker more with the arguments.

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• Automatically created NSManagedObject subclasses don't use ARC

  - by Jordan

  My project is ARC enabled (the build settings have Objective-C Reference Counting set to YES). There are no file exceptions to this, it is enabled project wide. (Latest stable version of Xcode). When I create an NSManagedObject subclass via File New for a Core Data entity, the generated header uses the following in its property declarations: @property (nonatomic, retain) But 'retain' is not ARC!! Is this a bug, or is there something I'm missing or not understanding? There are no build warnings - if this is a bug though, how can I remedy it?

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• GetAllUsers - MVC

  - by Jemes

  I’m using the Membership Provider and would like to display a list of all the users and their First Name, Last Name etc using the GetAllUsers function. I'm having trouble understanding how to implement this function in MVC. Has anyone implemented this in MVC or is there an easier way to list all the users in my application? Any help or advise would be really helpful. Controller public ActionResult GetUsers() { var users = Membership.GetAllUsers(); return View(users); } View Model public class GetUsers { [Required] [DisplayName("User name")] public string UserName { get; set; } [Required] [DisplayName("User name")] public string FirstName { get; set; } } View <%= Html.Encode(item.UserName) %> Error The model item passed into the dictionary is of type 'System.Web.Security.MembershipUserCollection', but this dictionary requires a model item of type 'System.Collections.Generic.IEnumerable`1[Account.Models.GetUsers]'.

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• Handler invocation speed: Objective-C vs virtual functions

  - by Kerido

  I heard that calling a handler (delegate, etc.) in Objective-C can be even faster than calling a virtual function in C++. Is it really correct? If so, how can that be? AFAIK, virtual functions are not that slow to call. At least, this is my understanding of what happens when a virtual function is called: Compute the index of the function pointer location in vtbl. Obtain the pointer to vtbl. Dereference the pointer and obtain the beginning of the array of function pointers. Offset (in pointer scale) the beginning of the array with the index value obtained on step 1. Issue a call instruction. Unfortunately, I don't know Objective-C so it's hard for me to compare performance. But at least, the mechanism of a virtual function call doesn't look that slow, right? How can something other than static function call be faster?

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• Examples of when to use PageAsyncTask (Asynchronous asp.net pages)

  - by Tony_Henrich

  From my understanding from reading about ASP.NET asynchronous pages, the method which executes when the asynchronous task begins ALWAYS EXECUTES between the prerender and the pre-render Complete events. So because the page's controls' events run between the page's load and prerender events, is it true that whatever the begin task handler (handler for BeginAsync below) produces, it can't be used in the controls' events? So for example, if the handler gets data from a database, the data can't be used in any of the controls' postback events? Would you bind data to a data control after prerender? PageAsyncTask pat = new PageAsyncTask(BeginAsync, EndAsync, null, null, true); this.RegisterAsyncTask(pat);

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• Windows 64-bit registry v.s. 32-bit registry

  - by George2

  Hello everyone, I heard on Windows x64 architecture, in order to support to run both x86 and x64 application, there is two separate/different sets of Windows registry -- one for x86 application to access and the other for x64 application to access? For example, if a COM registers CLSID in the x86 set of registry, then x64 application will never be able to access the COM component by CLSID, because x86/x64 have different sets of registry? So, my question is whether my understanding of the above sample is correct? I also want to get some more documents to learn this topic, about the two different sets of registry on x64 architecture. (I did some search, but not found any valuable information.) thanks in advance, George

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• Maven grails plugin issue

  - by Jack

  I'm trying to create the pom for an existing grails project via: mvn grails:create-pom -Dourcompany.com Now, we have our maven repository available in a local nexus repo: http://ourcompany.com/nexus But when i run the above, i get the below error Downloading: http://ourcompany.com/nexus/content/groups/public/ourcompany/com/hibernate-core/3.3.1.GA/hibernate-core-3.3.1.GA.jar [INFO] Unable to find resource 'ourcompany.com:hibernate-core:jar:3.3.1.GA' in repository central (http://repo1.maven.org/maven2) [INFO] ------------------------------------------------------------------------ [ERROR] BUILD ERROR But it is in there at simply: http://ourcompany.com/nexus/content/groups/public/hibernate-core/3.3.1.GA/hibernate-core-3.3.1.GA.jar Ie, w/o the "ourcompany.com" path. From my perspective, it should just try to pull down hibernate w/o inserting the groupId, but maybe i'm not understanding how i'm supposed to run this command?

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