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• Google maps spatial reference system

  - by JavaRocky

  What is Google map's spatial reference system using when you enter a lat, long into the maps search bar? I've found hints that it might be WGS84 but after converting to that coordinate system, nothing shows up when i paste the coordinates into the google maps search box. I am converting from GDA MGA 56. Sample: Input MGA56 coords: 336301, 6253363 Expected WGS86 coords: -33.8473340793201, 151.230631835944 I get: 16834916.928327594 -4008321.1020318186 Spatial coord systems: EPSG:28356 for MGA56 EPSG:900913 for WGS86 (google maps) I am using geotools to do the transform: CoordinateReferenceSystem crsMga56 = CRS.parseWKT(mga56); CoordinateReferenceSystem crsGmaps = CRS.parseWKT(gmaps); Coordinate coordinate = new Coordinate(336301, 6253363); Point point = new GeometryFactory().createPoint(coordinate); MathTransform transform = CRS.findMathTransform(crsMga56, crsGmaps); Geometry geometry = JTS.transform(point, transform); I know the transform is not correct, as when i use an online tool it gives me the correct coords. http://www.environment.gov.au/cgi-bin/transform/mga2geo%5Fgda.pl?east=336301&north=6253363&zone=56

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• Database storage for high sample rate data in web app

  - by Jim

  I've got multiple sensors feeding data to my web app. Each channel is 5 samples per second and the data gets uploaded bundled together in 1 minute json messages (containing 300 samples). The data will be graphed using flot at multiple zoom levels from 1 day to 1 minute. I'm using Amazon SimpleDB and I'm currently storing the data in the 1 minute chunks that I receive it in. This works well for high zoom levels, but for full days there will be simply be too many rows to retrieve. The idea I've currently got is that every hour I can crawl through the data and collect together 300 samples for the last hour and store them in an hour Domain (table if you like). Does this sound like a reasonable solution? How have others implemented the same sort of systems?

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• kill -9 and production application

  - by valodzka

  Which problem can cause kill -9 in production application (in linux to be exact)? I have application which do some periodical work, stopping these takes long time, and I don't care if some jobs will be aborted - work can be finished by new processes. So can I use kill -9 just to stop it immediately or this can cause serious OS problems? For example, Unicorn, uses it as normal working procedure: When your application goes awry, a BOFH can just "kill -9" the runaway worker process without worrying about tearing all clients down, just one. But this article claims: The -9 (or KILL) argument to kill(1) should never be used on Unix systems

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• Encryption using rijndael

  - by user363295

  Hi all. I'm quite new in programming .I wrote the below code in order to prompt the user for a password to encrypting a file, But it just work when the length of password is 8, What can I do on order to accepting any number of characters for the password? string pass = textBox2.Text.ToString(); string password = @"" + pass + ""; UnicodeEncoding UE = new UnicodeEncoding(); byte[] key = UE.GetBytes(password); FileStream fsCrypt = new FileStream(@"c:\\users\\new", FileMode.Create); name = fsCrypt.Name; RijndaelManaged RMCrypto = new RijndaelManaged(); CryptoStream cs = new CryptoStream(fsCrypt, RMCrypto.CreateEncryptor(key, key), CryptoStreamMode.Write); FileStream fsIn = new FileStream(filename, FileMode.Open); int data; while ((data = fsIn.ReadByte()) != -1) cs.WriteByte((byte)data);

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• Weird use of generics

  - by Karl Trumstedt

  After a bit of programming one of my classes used generics in a way I never seen before. I would like some opinions of this, if it's bad coding or not. abstract class Base<T> : where T : Base<T> { // omitted methods and properties. virtual void CopyTo(T instance) { /*code*/ } } class Derived : Base<Derived> { override void CopyTo(Derived instance) { base.CopyTo(instance); // copy remaining stuff here } } is this an OK use of generics or not? I'm mostly thinking about the constraint to "itself". I sometimes feel like generics can "explode" to other classes where I use the Base class.

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• iphone using 2 tableview

  - by Anonymous

  Hi, I 'm a iphone programming newbie. I m trying to implement an app with multi-level tableviews. The idea is if someone selects something on the first screen say then a new view opens(tableview) car make> list of models Honda > Acura, S2000,accord ... My challenge is to show the list of models in a new tableview & secondly change the size of hte list depending on the car selected. I have programmed so that when i select 'Honda' a new tableview opens. How do i populate data for the second table?? Any suggestions on how to proceed? thanks

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• iPhone or Android for development?

  - by user974873

  I have programming experience and would like to start developing for mobile platforms. Now I see that iPhone and Android are both dominating he smartphone market, but also that more and more people are buying iPhones. Which one would be better to start developing for? I currently do not own a Mac but would purchase a Mac Mini if I was to buy an iPhone. Would it be better to buy iPhone and Mac because it will be better in the long run because of the amount of users or Android?

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• Non laggy movement in Flex or WPF

  - by PaN1C_Showt1Me

  I'm trying to learn something about 2D games programming. For this purpose I've downloaded many samples developed in: Flex and Microsoft WPF. I've noticed that all the animations / moving objects are kind of non-smooth. I've seen a Flex example with double buffering which solved the image flickering, but it was laggy too. WPF example too. Just to mentioned, all examples were drawing on Canvas. I'm just curious, is it possible to have a wonderful non-laggy movement on the GUI in Flash or WPF ? (e.g. like a real game, coded in C++)

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• How should I structure my git commits?

  - by int3

  I'm trying to contribute to open source software for the first time, but I'm pretty inexperienced with version control systems. In particular, right now I want to make a number of changes to different parts of the code, but I'm not sure if the maintainer would want to integrate all of them into the master repository. However, the changes I'll be making are independent, i.e. they affect different parts of the file, or parts of different files. How should I go about making the changes? If I make a string of commits on the same branch, will the maintainer be able to pick and choose what he wants from the individual commit? E.g. can he patch in the changes I made in my second commit while ignoring the first one? Or should I make each change in a separate branch?

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• What things on a job listing should be avoided?

  - by Earlz

  Hello, I'm looking at trying my hand at a bit of freelancing. And looking at some of the listings, I can tell some of them are definitely, obviously wrong. "A web application mimicking youtube. Project must be completed in 2 weeks. Flat payment of $200. If you are not willing to do things this fast paced then do not apply" But some of them are more subtle and they give me a red flag inside, but I'm not sure to avoid them. What are some things in job listings to avoid for freelance programming jobs? What is the reason for avoiding that?

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• strategies for learning complex software packages

  - by Tom

  I am a fairly novice Java programmer and I am currently working on a project to extend a piece of software that has been developed over a few years. So it has pretty big code base and the previous developers knew it well, so extending it is not going to be easy without a thorough understanding of the structure and function. 1) I had begun by trying to tackle small parts of the system and document them with mindmap. (particularly I am trying to document the interactions with external systems) 2) I have the book "code complete", which I am working through. 3) I have pointed some tools like "tattletale" at the code to get some diagrams of dependency relationships. What other strategies should I employ, should I focus on one particular aspect?

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• Ethics of assisting other programmers, where do we draw the line?

  - by Chris

  In general, not just in relation to stackoverflow, sometimes I'm asked a programming question for which the answer will probably be used for good purposes, but there is a chance that it could not be. Two recent examples which reminded me of some real world questions I've been asked are: Send email to many users, and keep a formless application from closing for a keyboard hook Though I don't believe the intent of the authors of those questions is in any way nefarious, occasionally someone does ask such a question for purposes of aiding a spamming effort, or creating a keylogger. Even though the questioner and answerers had good intent, a 3rd party could pervert those answers to create a piece of malware or a spam utility. Should we always trust the questioner to use the answer for good? Should we feel obligated to ask the purpose of a question, and how the answer will be used? And how can we prevent answers from being overheard (when asked verbally) or being referenced (when posted publicly online) and then used for unsavory purposes?

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• Manipulating the address of a variable to store a smaller type?

  - by Sidnicious

  This is what I get for pampering myself with high-level programming languages. I have a function which writes a 32-bit value to a buffer, and a uint64_t on the stack. Is the following code a sane way to store it? uint64_t size = 0; // ... getBytes((uint32_t*)&size+0x1); I'm assuming that this would be the canonical, safe style: uint64_t size = 0; // ... uint32_t smallSize; getBytes(&smallSize); size = smallSize;

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• Building a minimal plugin architecture in Python.

  - by dF

  I have an application, written in Python, which is used by a fairly technical audience (scientists). I'm looking for a good way to make the application extensible by the users, i.e. a scripting/plugin architecture. I am looking for something extremely lightweight. Most scripts, or plugins, are not going to be developed and distributed by a third-party and installed, but are going to be something whipped up by a user in a few minutes to automate a repeating task, add support for a file format, etc. So plugins should have the absolute minimum boilerplate code, and require no 'installation' other than copying to a folder (so something like setuptools entry points, or the Zope plugin architecture seems like too much.) Are there any systems like this already out there, or any projects that implement a similar scheme that I should look at for ideas / inspiration?

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• Importing ctype; embedding python in C++ application

  - by Drew

  I'm trying to embed python within a C++ based programming language (CCL: The compuatational control language, not that any of you have heard of it). Thus, I don't really have a "main" function to make calls from. I have made a test .cc program with a main, and when I compile it and run it, I am able to import my own python modules and system modules for use. When I embed my code in my CCL-based program and compile it (with g++), it seems I have most functionality, but I get the import error: ImportError: /usr/lib/python2.6/lib-dynload/_ctypes.so: undefined symbol: PyType_GenericNew Can someone explain this to me and how to go about solving it? It seems like I've linked the objects correctly. Thanks.

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• JavaScript socket vs. Flash socket?

  - by Dr.Dredel

  Steve Jobs just posted this article on why Apple rejects Flash... http://www.apple.com/hotnews/thoughts-on-flash/ I agree that javascript and css can be used to replicate some of Flash's animation, though Flash does all sorts of scaling and tweening that is incredibly powerful, and I'm not sure that there's anything comparable in javascript, if there is, I certainly haven't seen it. However, my question is about the socket. Flash has an incredibly powerful openSocket class that allows you to connect to a server and have the server and the client talk back and forth to one another. As far as I know there is no equivalent class in Javascript. Am I mistaken? Is there some secret mystery Ajax class that replicates the openSocket? If not, then that feature alone makes Flash an invaluable tool. I'm interested in all answers though... and yes this IS a programming question! :)

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• Garbage collection when compiling to C

  - by Jules

  What are the techniques of garbage collection when compiling a garbage collected language to C? I know of two: maintain a shadow stack that saves all roots explicitly in a data structure use a conservative garbage collector like Boehm's The first technique is slow, because you have to maintain the shadow stack. Potentially every time a function is called, you need to save the local variables in a data structure. The second technique is also slow, and inherently does not reclaim all garbage because of using a conservative garbage collector. My question is: what is the state of the art of garbage collection when compiling to C. Note that I do not mean a convenient way to do garbage collection when programming in C (this is the goal of Boehm's garbage collector), just a way to do garbage collection when compiling to C.

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• Creating New Objects in JavaScript

  - by Ken Ray

  I'm a relatively newbie to object oriented programming in JavaScript, and I'm unsure of the "best" way to define and use objects in JavaScript. I've seen the "canonical" way to define objects and instantiate a new instance, as shown below. function myObjectType(property1, propterty2) { this.property1 = property1, this.property2 = property2 } // now create a new instance var myNewvariable = new myObjectType('value for property1', 'value for property2'); But I've seen other ways to create new instances of objects in this manner: var anotherVariable = new someObjectType({ property1: "Some value for this named property", property2: "This is the value for property 2" }); I like how that second way appears - the code is self documenting. But my questions are: Which way is "better"? Can I use that second way to instantiate a variable of an object type that has been defined using the "classical"way of defining the object type with that implicit constructor? If I want to create an array of these objects, are there any other considerations? Thanks in advance.

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• Redirect Log output to sdcard on customer's phone

  - by Tom

  My customers are having a problem with my app, and I have been unable to reproduce the problem on my development phone. How to debug this problem? The android Log class is great, but my customers do not know how to use 'adb' or the USB debug cable. Is there some way to redirect Log output to a file on the phone's SD card? Then the customer could easily email the log file to me. Even if this redirection requires programming on my part, I could at least distribute a 'debug' version of the app. Thanks, Tom

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• Generating Dynamic web pages without server side scripting

  - by Microkernel

  Hi guys, I am trying to control a media device which has lot of multimedia content that it can play using another device(remote control device) like an ipad connected to the LAN. (UPnP) I want the media device to be able to send the content listing to the remote device so that it will be rendered as a webpage on the remote controller. And actions on the webpages needs to be sent to the the device as commands to execute (like play, pause, next etc). The media device is an embedded device, hence can't have any server side scripting, all has to be done on the client side. I want the page rendered to be HTML5. So, is it possible to generate dynamic HTML5 pages using just client side scripting? Thanks a lot. I am an embedded systems developer hence clueless about the web designing stuff.

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• java runtime tracing library to replace system.out.println

  - by Grzegorz Oledzki

  Have you heard of any library which would allow me to set up a tracing for specific methods at runtime? Instead of adding (and removing) lots of System.out.println in my code (and having to re-compile and re-deploy) I would like to have a magic thing which would print out a line for each call of selected method without any change in the code. This would work without re-compiling, so some kind of JVM agent (or some non-standard JVM would be needed?). Sounds like a job for aspect programming? A typical scenario would be to start an application, configure the traced methods dynamically (in a separate file or similar) and then everytime a selected method is called a line with its name (and arguments) is printed out to System.out (or some log file). Naturally one could think of tens of additional features, but this basic set would be a great tool. BTW, I use Eclipse interactive debugger too, not only the System.out tracing technique, but both have some advantages and sometimes Eclipse is not enough.

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• What's the coolest machine you've ever worked on?

  - by mxg

  What's the most exotic, coolest, unique, or interesting machine you've worked on? Most of us work on machines with x86 architectures using some Windows or Linux variant. I'm sure there are those of you out there who are working on or have worked on machines with experimental architecures, or operating systems. Maybe you worked on a machine that has some sigificance in the history of computing. I'd be interested to hear about it. I'm sure others reading SO will as well. EDIT: I appreciate all of you who took some time to talk about their experiences with interesting or unusual machines. I enjoyed reading your answers. Although it wasn't my intent to get nostalgic, I see that theme amongst the responses.

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• Good way to cache data during Android application lifecycle?

  - by sniurkst

  Hello, keeping my question short, I have creating application with 3 activities, where A - list of categories, B - list of items, C - single item. Data displayed in B and C is parsed from online XML. But, if I go trough A - B1 - C, then back to A and then back to B1 I would like to have it's data cached somewhere so I wouldn't have to request XML again. I'm new to Android and Java programming, I've googled a lot and still can't find (or simply do not have an idea where to look) a way to do what I want. Would storing all received data in main activity A (HashMaps? ContentProviders?) and then passing to B and C (if they get same request that was before) be a good idea?

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• Cross-platform GUI toolkits with WPF-style composition capabilities

  - by Alexey Romanov

  A huge advantage of WPF over, say, WinForms is its composability. To quote Programming WPF: One level up, WPF provides its “content model,” which allows any control to host any group of other controls. You don’t have to build special BitmapButton or IconComboBox classes; you put as many images, shapes, videos, 3D models, or whatever into a Button (or a ComboBox, ListBox, etc.) as suit your fancy. Are there any cross-platform GUI frameworks (preferably with Java bindings) out there which also let you do this?

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• Performance statistics hooks

  - by tinny

  Lets be honest, most software that developers produce has quite modest performance requirements. E.g. Systems perhaps serving 100's of requests per second, if that. But lets assume for a moment (or even dream) that you where perhaps involved in the "next big thing" (whatever that means) and you wanted to put some sort of performance statistics logging in place to help you out when all those users come flying in. Performance statistics logging, how would you approach this requirement? Perhaps you would use some sort of generic framework for this? Or roll your own solution? What would you log? How granular? Or would you not even bother putting anything in place and rather deal with this issue when it actually became an issue? It would be really interesting to hear your thoughts on this topic.

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