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• Are the formatted addresses of a Google location unique?

  - by Hans

  I want our users of a web site to be able to either search and pick an address or mark a location on a map decide how accurate this address/location is I am in the process of implementing the first part with jquery, jquery ui's autocomplete, google map, and google geocoder. For the second part I will generate a radiobutton list based on the address elements/alternatives of the first part on the client side with jquery. My concern, however, is how to convey the choices to the server side. The Google geocoder includes a number of useful metadata that I want to store. A possibility is to store the complete json object in a hidden form field, but I can't trust the users. Such a solution would enable an unfriendly insertion of spam in the data. If the addresses/locations would have a unique identifyer I could store just these and let the server refetch/evaluate the data. The alternative geonames.org web service has such ids. But are for example the formatted addresses of a Google location unique? Any tips?

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• Does anyone know of any good open source voting software?

  - by mezoid

  I'm looking for a voting system that we can implement at work amongst our developers. We need something that allows developers to submit ideas about what we can do to improve our development practices (amongst other things) and then have all the developers vote on the ideas to give everyone an idea of what ideas we should attempt to implement first. For example, our developers could list ideas for parts of our code base that should be improved/cleaned up and we'd be able to collectively vote on which parts to start on first. Something like www.uservoice.com might be one way of getting what we need but I'm still wanting to look at alternatives. Unfortunately, googling for voting and polling systems just doesn't seem to bring up any useful results because most of them seem geared towards elections and surveys rather than a way for people to make suggestions and vote on them. Does anyone here know of any sort of software system that might be able to do what I'm looking for? Better yet, does anyone have such a system set up for the developers at their work place? I'd be interested in knowing if it is useful at all.

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• Syncing two AS3 NetStreams

  - by Lowgain

  I'm writing an app that requires an audio stream to be recording while a backing track is played. I have this working, but there is an inconsistent gap in between playback and record starting. I don't know if I can do anything to make the sync perfect every time, so I've been trying to track what time each stream starts so I can calculate the delay and trim it server-side. This also has proved to be a challenge as no events seem to be sent when a connection starts (as far as I know). I've tried using various properties like the streams' buffer sizes, etc. I'm thinking now that as my recorded audio is only mono, I may be able to put some kind of 'control signal' on the second stereo track which I could use to determine exactly when a sound starts recording (or stick the whole backing track in that channel so I can sync them that way). This leaves me with the new problem of properly injecting this sound into the NetStream. If anyone has any idea whether or not any of these ideas will work, how to execute them, or some alternatives, that would be extremely helpful! Been working on this issue for awhile

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• UIDocumentInteractionController & ARC: [UIPopoverController dealloc] reached while popover is still visible

  - by muffel

  This issue or similar issues have been discussed here before, but I didn't find any working solution for me. I am using the following code to display a UIDocumentInteractionController on an ARC-enabled iOS 7 project: - (void) exportDoc{ // [...] docController = [UIDocumentInteractionController interactionControllerWithURL:[NSURL fileURLWithPath:path]]; docController.delegate = self; [docController presentOpenInMenuFromBarButtonItem:mainMenuButton animated:YES]; } First I didn't want to create a property that holds the controller reference, but as many people said that there are not alternatives to it. It is defined as @property (strong) UIDocumentInteractionController* docController; exportDoc is run in the main thread using NSOperationQueue. Whenever it is executed, I get the following error message: Terminating app due to uncaught exception 'NSGenericException', reason: '-[UIPopoverController dealloc] reached while popover is still visible.' This is what the backtrace says: (lldb) bt * thread #1: tid = 0x1c97d9, 0x000000019a23c1c0 libobjc.A.dylibobjc_exception_throw, queue = 'com.apple.main-thread', stop reason = breakpoint 2.1 frame #0: 0x000000019a23c1c0 libobjc.A.dylibobjc_exception_throw frame #1: 0x000000018d982e90 CoreFoundation+[NSException raise:format:] + 128 frame #2: 0x0000000190bc348c UIKit-[UIPopoverController dealloc] + 96 frame #3: 0x0000000190e18fc8 UIKit-[UIDocumentInteractionController dealloc] + 168 frame #4: 0x000000019a255474 libobjc.A.dylib(anonymous namespace)::AutoreleasePoolPage::pop(void*) + 524 frame #5: 0x000000018d881988 CoreFoundation_CFAutoreleasePoolPop + 28 frame #6: 0x000000018e42cb18 Foundation-[NSOperationInternal _start:] + 892 frame #7: 0x000000018e4eea38 Foundation__NSOQSchedule_f + 76 frame #8: 0x000000019a813fd4 libdispatch.dylib_dispatch_client_callout + 16 frame #9: 0x000000019a8171dc libdispatch.dylib_dispatch_main_queue_callback_4CF + 336 frame #10: 0x000000018d942c2c CoreFoundation__CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE + 12 frame #11: 0x000000018d940f6c CoreFoundation__CFRunLoopRun + 1452 frame #12: 0x000000018d881c20 CoreFoundationCFRunLoopRunSpecific + 452 frame #13: 0x0000000193511c0c GraphicsServicesGSEventRunModal + 168 frame #14: 0x00000001909b2fdc UIKitUIApplicationMain + 1156 * frame #15: 0x000000010000947c MyApplicationmain(argc=1, argv=0x000000016fdfbc80) + 108 at main.m:16 frame #16: 0x000000019a82faa0 libdyld.dylibstart + 4 As far as I understand the autoreleasepool just releases the controller. Shouldn't this be prevented by using a strong property just as I did? Do you have any idea what the problem can be and how I can solve it?

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• Best way to implement plugin framework - are DLLs the only way (C/C++ project)?

  - by Microkernel

  Introduction: I am currently developing a document classifier software in C/C++ and I will be using Naive-Bayesian model for classification. But I wanted the users to use any algorithm that they want(or I want in the future), hence I went to separate the algorithm part in the architecture as a plugin that will be attached to the main app @ app start-up. Hence any user can write his own algorithm as a plugin and use it with my app. Problem Statement: The way I am intending to develop this is to have each of the algorithms that user wants to use to be made into a DLL file and put into a specific directory. And at the start, my app will search for all the DLLs in that directory and load them. My Questions: (1) What if a malicious code is made as a DLL (and that will have same functions mandated by plugin framework) and put into my plugins directory? In that case, my app will think that its a plugin and picks it and calls its functions, so the malicious code can easily bring down my entire app down (In the worst case could make my app as a malicious code launcher!!!). (2) Is using DLLs the only way available to implement plugin design pattern? (Not only for the fear of malicious plugin, but its a generic question out of curiosity :) ) (3) I think a lot of softwares are written with plugin model for extendability, if so, how do they defend against such attacks? (4) In general what do you think about my decision to use plugin model for extendability (do you think I should look at any other alternatives?) Thank you -MicroKernel :)

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• Writing functions of tuples conveniently in Scala

  - by Alexey Romanov

  Quite a few functions on Map take a function on a key-value tuple as the argument. E.g. def foreach(f: ((A, B)) ? Unit): Unit. So I looked for a short way to write an argument to foreach: > val map = Map(1 -> 2, 3 -> 4) map: scala.collection.immutable.Map[Int,Int] = Map(1 -> 2, 3 -> 4) > map.foreach((k, v) => println(k)) error: wrong number of parameters; expected = 1 map.foreach((k, v) => println(k)) ^ > map.foreach({(k, v) => println(k)}) error: wrong number of parameters; expected = 1 map.foreach({(k, v) => println(k)}) ^ > map.foreach(case (k, v) => println(k)) error: illegal start of simple expression map.foreach(case (k, v) => println(k)) ^ I can do > map.foreach(_ match {case (k, v) => println(k)}) 1 3 Any better alternatives?

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• Toolbox/framework to construct lightweight public-facing web site

  - by aSteve

  I am aware of full-blown content management systems (CMS) such as SugarCRM and TikiWiki... where content is typically stored in a database... and edited through the same interface as it is published. While I like many of the features, the product is clearly aimed at enterprise-wide use rather than to be public-facing. What I'd like to establish are potential alternatives that fill the space between full-blown CMS and hand-coded bespoke site. I like the way that I can add modules to my CMS... allowing me to quickly introduce new functionality, and I'd like an analogous feature in a system for public web-content. Modules I know I'd like include moderated comments; web-form-to-email gateway; menus/tabs... in future, perhaps mapping or diaries or RSS integration - etc. Where my requirements differ from a CMS, I don't need (or want) most content to be editable through the main site... and, somehow, I do want to be able to preview how updates will be presented to the public rather than to make live changes. For these purposes, in contrast to those where a typical CMS would be ideal, presentation is of paramount importance - and trumps any desire to immediately disseminate information. I realise that this is a very high-level question... (suggestions of additional tags welcome) - I mentioned PHP only as - ideally - I'm looking for an open source solution and a PHP deployment is an easy option. What are my options?

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• Modifying resource contents of a running executable

  - by mrwoik

  All, I store my application settings in a resource. When my program first loads, I read the specified resource using WinAPI. I then parse the retrieved byte data. This works flawlessly for me. Now let's say that a user alters a setting in my application. He/she checks a checkbox control. I would like to save the updated setting to my resource. However, it seems that my call to UpdateResource will not work while my application is running. I can't modify my resource data even though it is the same size. First, is it possible to modify a running image's resource data? Second, if that is not possible, what alternatives do I have for storing settings internally within my application? NOTE: I must have the settings within my running executable. They cannot be on the harddrive or in the registry. Please don't even suggest that as an option.

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• HREF link that targets nothing, does not want to use hash or void(0)

  - by Mattis

  I have a link that I want to be able to click to trigger a piece of jQuery code. Currently I have <a href="#" id="foo">Link</a> and $('#foo').click(function(){ // Do stuff }); which works well. But, I have always hated using hash in this way. The page flickers and the hash is added to the page url. One alternative is to use <a href="javascript:void(0);" id="foo">Link</a> but I also dislike seeing that piece of code in the browser status bar. It looks tacky. What I'd rather have is an explanatory javascript placeholder that does nothing, like <a href="javascript:zoom();" id="foo">Link</a> which actually works, but throws an ReferenceError in the javascript console since there are no such function. What's the minimum definition of a function that does nothing? Are there any other alternatives? Should I just skip the link and use something like <span id="foo" style="cursor:pointer;cursor:hand;">Link</span> instead?

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• Self organizing layouts

  - by user613326

  Quite a while ago i was more in websites building then i am now. In my time there where huge debates about what to use; tables or pure CSS alternatives. I went out of the webdesigning, but now an old question re-surfaces. What i would like to create is a web page design that depending on screensize, would self organize the page into columns, so that for example on a PDA it would show 1 column On an old computer monitor, it would show 2 colomns, and on a widescreen laptop it would show 3 columns. I forgot how this was called and how it was done in the past, it had to do with XML and storing data seperate from design (if i remember well), perhaps these days better methods exist to do that, does this, anyone ring this a bell ? Also i note a lot is possible with Jquery and and brouwser depending webkits. But i need to make sure that it would run on all (modern) brouwsers : Iexplorer, Firefox, chrome And Jquery is nice too, but i am kinda woried that some day one of these brouwser vendors decides that jscript like java isnt enabled by default (or is that very unlikely ?)11 Perhaps someone can point me to a method that is the prefered way to do this.

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• Indexing/Performance strategies for vast amount of the same value

  - by DrColossos

  Base information: This is in context to the indexing process of OpenStreetMap data. To simplify the question: the core information is divided into 3 main types with value "W", "R", "N" (VARCHAR(1)). The table has somewhere around ~75M rows, all columns with "W" make up ~42M rows. Existing indexes are not relevant to this question. Now the question itself: The indexing of the data is done via an procedure. Inside this procedure, there are some loops that do the following: [...] SELECT * FROM table WHERE the_key = "W"; [...] The results get looped again and the above query itself is also in a loop. This takes a lot of time and slows down the process massivly. An indexon the_key is obviously useless since all the values that the index might use are the same ("W"). The script itself is running with a speed that is OK, only the SELECTing takes very long. Do I need to create a "special" kind of index that takes this into account and makes the SELECT quicker? If so, which one? need to tune some of the server parameters (they are already tuned and the result that they deliver seem to be good. If needed, I can post them)? have to live with the speed and simply get more hardware to gain more power (Tim Taylor grunt grunt)? Any alternatives to the above points (except rewriting it or not using it)?

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• Approach for caching data from data logger

  - by filip-fku

  Greetings, I've been working on a C#.NET app that interacts with a data logger. The user can query and obtain logs for a specified time period, and view plots of the data. Typically a new data log is created every minute and stores a measurement for a few parameters. To get meaningful information out of the logger, a reasonable number of logs need to be acquired - data for at least a few days. The hardware interface is a UART to USB module on the device, which restricts transfers to a maximum of about 30 logs/second. This becomes quite slow when reading in the data acquired over a number of days/weeks. What I would like to do is improve the perceived performance for the user. I realize that with the hardware speed limitation the user will have to wait for the full download cycle at least the first time they acquire a larger set of data. My goal is to cache all data seen by the app, so that it can be obtained faster if ever requested again. The approach I have been considering is to use a light database, like SqlServerCe, that can store the data logs as they are received. I am then hoping to first search the cache prior to querying a device for logs. The cache would be updated with any logs obtained by the request that were not already cached. Finally my question - would you consider this to be a good approach? Are there any better alternatives you can think of? I've tried to search SO and Google for reinforcement of the idea, but I mostly run into discussions of web request/content caching. Thanks for any feedback!

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• Hibernate: fetching multiple bags efficiently

  - by Jens Jansson

  Hi! I'm developing a multilingual application. For this reason many objects have in their name and description fields collections of something I call LocalizedStrings instead of plain strings. Every LocalizedString is basically a pair of a locale and a string localized to that locale. Let's take an example an entity, let's say a book -object. public class Book{ @OneToMany private List<LocalizedString> names; @OneToMany private List<LocalizedString> description; //and so on... } When a user asks for a list of books, it does a query to get all the books, fetches the name and description of every book in the locale the user has selected to run the app in, and displays it back to the user. This works but it is a major performance issue. For the moment hibernate makes one query to fetch all the books, and after that it goes through every single object and asks hibernate for the localized strings for that specific object, resulting in a "n+1 select problem". Fetching a list of 50 entities produces about 6000 rows of sql commands in my server log. I tried making the collections eager but that lead me to the "cannot simultaneously fetch multiple bags"-issue. Then I tried setting the fetch strategy on the collections to subselect, hoping that it would do one query for all books, and after that do one query that fetches all LocalizedStrings for all the books. Subselects didn't work in this case how i would have hoped and it basically just did exactly the same as my first case. I'm starting to run out of ideas on how to optimize this. So in short, what fetching strategy alternatives are there when you are fetching a collection and every element in that collection has one or multiple collections in itself, which has to be fetch simultaneously.

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• Application that depends heavily on stored procedures

  - by PieterG

  We currently have an application that depends largely on stored procedures. There is a heavy use of temp tables. It's an extremely large application. Facing this situation, I would like to use Entity Framework or Linq2Sql for a rewrite. I might consider using Fluent Hibernate or Subsonic, as i've used them quite extensively in the past. I've had problems with Linq2Sql generating the return types for the stored procedures because of the usage of the temp tables, and I think it's cumbersome to go and change all the stored procedures from temp tables to in-memory tables. Considering the 2 choices that I want to make, which one of the 2 is the best route to go and why? If my choices are extremely idiotic, please provide alternatives. Edit: The reason for the question and the change is that the data access layer is non-existent and was built 10 years ago. We currently still run into a lot of issues with it. I don't want to divulge too much, but if you saw it, your eyes would start bleeding :)

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• Where to store: User connection information?

  - by TomTom

  ;) I am writing a .NET application wher ethe user connects to a given server. ALl information within the application is stored in the server. But I want / need to store the following information for the user: The server he connected to last The username he used to connect last (and no, no password, never ever). Any idea where to store this best? the application config file is not sensible (user != admin, application.config is write protected for him). So, my options are: In the registry. 2 keys under my own subkey. In a sort of ini file, stored in the user's data directory (AppData). This would possibly also allow later expansion (into like saving more information, some of which may not fit into the registry). Anyone a tip? Other alternatives? I tend so far to go for the AppData directory with my own subfolder - simply because it is a nice preparation for later to keep like a local copy of configuration etc.

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• Quick and easy flood protection?

  - by James P

  I have a site where a user submits a message using AJAX to a file called like.php. In this file the users message is submitted to a database and it then sends a link back to the user. In my Javascript code I disabled the text box the user types into when they submit the AJAX request. The only problem is, a malicious user can just constantly send POST requests to like.php and flood my database. So I would like to implement simple flood protection. I don't really want the hassle of another database table logging users IPs and such... as if they are flooding my site there will be a lot of database read/writes slowing it down. I thought about using sessions, like have a session that contains a timestamp that gets checked every time they send data to like.php, and if the current time is before the timestamp let them add data to the database, otherwise send out an error and block them. If they are allowed to enter something into the database, update their session with a new timestamp. What do you think? Would this be the best way to go about it or are there easier alternatives? Thanks for any help. :)

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• Cross-platform HTML application options

  - by Charles

  I'd like to develop a stand-alone desktop application targeting Windows (XP through 7) and Mac (Tiger through Snow Leopard), and if possible iPhone and Android. In order to make it all work with as much common code as possible (and because it's the only thing I'm good at), I'd like to handle the main logic with HTML and JS. Using Adobe AIR is a possibility. And I think I can do this with various application wrappers, using .NET for Windows XP, Objective C for iPhone, Java for Android and native "widget" platform support for Mac and Windows Vista & 7 (though I'd like to keep the widget in the foreground, so the Mac dashboard isn't ideal). Does anyone have any suggestions on where to start? The two sticking points are: I'll certainly need some form of persistent storage (cookies perhaps) to keep state between sessions I'll also probably need access to remote data files, so if I use AJAX and the hosting HTML file resides on the device, it will need to be able to do cross-domain requests. I've done this on the iPhone without any problems, but I'd be surprised if this were possible on other platforms. For me, Android and iPhone will be the easiest to handle, and it looks like I can use Adobe AIR to handle the rest. But I wanted to know if there are any other alternatives. Does anyone have any suggesions?

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• Showing multiple models in a single ListView

  - by Veer

  I've three models (Contacts, Notes, Reminders). I want to search all these and produce the filtered result in a single listview and depending upon the selection I've to display the corresponding view(UserControl) to its right. I want the right way of implementing the design or atleast alternatives to this method that I've tried. Now I've tried it using a IntegratedViewModel having all the properties from all the three models. public class IntegratedViewModel { ContactModel _contactModel; NoteModel _noteModel; public IntegratedViewModel(ContactModel contactModel) { _contactModel = contactModel; } // similarly for other models also public string DisplayTitle // For displaying in ListView { get; //same as set set { If(_contactModel != null) return _contactModel.Name; If(_noteModel != null) return _noteModel.Title; } } // All other properties from the three models includin the Name/Title properties for displaying them in the corresponding views(UserControl) } Now I set the itemsSource as the List<IntegratedViewModel>. I've to now bind the visibility of the views to some properties in the MainViewModel. I tried setting bool properties like IsContactViewSelected, IsNoteViewSelected using the setter of SelectedEntity property which is bound to the ListView's SelectedItem. public SelectedEntity { //get set { oldvalue = _selectedEntity; _selectedEntity = value; // now i find the Type of model selected using oldvalue.ModelType // where ModelType is a property in the IntegratedViewModel // according to the type, i set one of the above bool properties to false // and do the same for _selectedEntity but set the property to true // so that the view corresponding to the selectedEntityType is visible // and others are collapsed } } Here is the problem: For eg: let us say, I selected an item of type ContactModel, the old selection being NoteModel. I set the property IsNoteModelSelected to false according to the oldvalue, it sets the property and then Raises the propertychanged event and does not go and check the remaining if condition where i check for _selectedEntity which is used to set the IsContactModelSelected to true.

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• Windows 2008 VPS hosting experiences

  - by Luke Bennett

  Whilst similar questions exist, I couldn't find any which quite match my request. I'm looking for hosting for some personal .NET projects which for various reasons I do not want to host on our servers at work. I need to be able to host multiple sites and for that reason I'm thinking of a VPS with RDP access for the time being - don't fancy shared hosting as I feel that doesn't offer me the flexbility and control I'm looking for. What experiences do people have of Windows 2008 VPS providers? I've come across a few possibilities although it seems a lot of places are still on Windows 2003 with 2008 'coming soon'. Is VPS the best way to go? Eventually (depending on how the projects take off) I intend to get a dedicated box but at this stage it's not cost-effective. Also, what are people's experiences of running SQL Server Express on a VPS? What would you say the minimum requirements are for CPU/memory? I know it's not going to be anywhere near as performant as SQL Server 2005/8 running on a dedicated box but I'm hoping it will be an acceptable starting point. Any other tips/advice also welcome! Edit: Forgot to mention, I'm ideally looking for UK hosting although I'm open to alternatives.

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• Database source control with Oracle

  - by borjab

  I have been looking during hours for a way to check in a database into source control. My first idea was a program for calculating database diffs and ask all the developers to imlement their changes as new diff scripts. Now, I find that if I can dump a database into a file I cound check it in and use it as just antother type of file. The main conditions are: Works for Oracle 9R2 Human readable so we can use diff to see the diferences. (.dmp files doesn't seem readable) All tables in a batch. We have more than 200 tables. It stores BOTH STRUCTURE AND DATA It supports CLOB and RAW Types. It stores Procedures, Packages and its bodies, functions, tables, views, indexes, contraints, Secuences and synonims. It can be turned into an executable script to rebuild the database into a clean machine. Not limitated to really small databases (Supports least 200.000 rows) It is not easy. I have downloaded a lot of demos that does fail in one way or another. EDIT: I wouldn't mind alternatives aproaches provided that they allows us to check a working system against our release DATABASE STRUCTURE AND OBJECTS + DATA in a bath mode. By the way. Our project has been developed for years. Some aproaches can be easily implemented when you make a fresh start but seem hard at this point. EDIT: To understand better the problem let's say that some users can sometimes do changes to the config data in the production eviroment. Or developers might create a new field or alter a view without notice in the realease branch. I need to be aware of this changes or it will be complicated to merge the changes into production.

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• Easy ways to investigate unknown Python APIs

  - by jedi_coder

  When studying a snippet of unknown Python code, I occasionally bump into the varName.methodName() pattern. To figure out what's this, I shall study the code more, find where varName was instantiated, find its type. So if varName proves to be an instance of ClassName class, I would knew that methodName() is a method of ClassName. Sometimes varName == self and methodName() is a method of this class, or a method inherited from some other class, if the current class is subclassing some other classes. Are there quick ways / tools that could take 'methodName' as input, scan over all installed Python modules and show which classes have methodName()? The closest thing related to this I know of is ipython. If I type a class name, then dot ('.') then TAB, it can show the class members. Instead of a class I could use a name of an object (which is an instance of a certain class) and it would work too. As soon as I choose a method name from the provided options, I can type '?' or '??' and get some help if there's a docstring. I wonder if ipython can do some intelligent scanning based only on 'methodName' string. If you know alternatives to ipython that could possibly help with this, please do suggest them.

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• jQuery + form + textinput > Is it possible to display one value in a textinput and submit another?

  - by Ivan Kruchkoff

  I'm working on an application where dates are passed as yyyy-mm-dd but displayed to the client as mm-dd-yyyy (US based client). I'm using a jQuery datepicker for selecting from/to dates in a report and would like to show the dates to the client as mm-dd-yyyy but when the form is submitted, submit as yyyy-mm-dd. Is it possible to display one value in a textinput textbox and have another submitted without needing to hook into onSubmit? I've come up with the following alternatives: Hide the text input for the from and to fields, create dummy fields and make use of the following jQuery date picker functions: altField and altFormat to display the value to the client in their preferred way and deal only with the submitted values which are set through the alt functions. Have an onSubmit javascript call to change the dates from mm-dd-yyyy to dd-mm-yyyy and also change the value=" to change the date to the client's preferred format. Rewrite the app to handle all dates in mm-dd-yyyy and hope the client never has non-US customers that would like their dates in a specific format. Change all dates to dd-Mon-YYYY e.g. 26-May-2010 as all of our client's customers are guaranteed to be English only.

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• How to lazy load a data structure (python)

  - by Anton Geraschenko

  I have some way of building a data structure (out of some file contents, say): def loadfile(FILE): return # some data structure created from the contents of FILE So I can do things like puppies = loadfile("puppies.csv") # wait for loadfile to work kitties = loadfile("kitties.csv") # wait some more print len(puppies) print puppies[32] In the above example, I wasted a bunch of time actually reading kitties.csv and creating a data structure that I never used. I'd like to avoid that waste without constantly checking if not kitties whenever I want to do something. I'd like to be able to do puppies = lazyload("puppies.csv") # instant kitties = lazyload("kitties.csv") # instant print len(puppies) # wait for loadfile print puppies[32] So if I don't ever try to do anything with kitties, loadfile("kitties.csv") never gets called. Is there some standard way to do this? After playing around with it for a bit, I produced the following solution, which appears to work correctly and is quite brief. Are there some alternatives? Are there drawbacks to using this approach that I should keep in mind? class lazyload: def __init__(self,FILE): self.FILE = FILE self.F = None def __getattr__(self,name): if not self.F: print "loading %s" % self.FILE self.F = loadfile(self.FILE) return object.__getattribute__(self.F, name) What might be even better is if something like this worked: class lazyload: def __init__(self,FILE): self.FILE = FILE def __getattr__(self,name): self = loadfile(self.FILE) # this never gets called again # since self is no longer a # lazyload instance return object.__getattribute__(self, name) But this doesn't work because self is local. It actually ends up calling loadfile every time you do anything.

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• Permutations distinct under given symmetry (Mathematica 8 group theory)

  - by Yaroslav Bulatov

  Given a list of integers like {2,1,1,0} I'd like to list all permutations of that list that are not equivalent under given group. For instance, using symmetry of the square, the result would be {{2, 1, 1, 0}, {2, 1, 0, 1}}. Approach below (Mathematica 8) generates all permutations, then weeds out the equivalent ones. I can't use it because I can't afford to generate all permutations, is there a more efficient way? Update: actually, the bottleneck is in DeleteCases. The following list {2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0} has about a million permutations and takes 0.1 seconds to compute. Apparently there are supposed to be 1292 orderings after removing symmetries, but my approach doesn't finish in 10 minutes removeEquivalent[{}] := {}; removeEquivalent[list_] := ( Sow[First[list]]; equivalents = Permute[First[list], #] & /@ GroupElements[group]; DeleteCases[list, Alternatives @@ equivalents] ); nonequivalentPermutations[list_] := ( reaped = Reap@FixedPoint[removeEquivalent, Permutations@list]; reaped[[2, 1]] ); group = DihedralGroup[4]; nonequivalentPermutations[{2, 1, 1, 0}]

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• OSGi bundle imports packages from non-bundle jars: create bundles for them?

  - by John Simmons

  I am new to OSGi, and am using Equinox. I have done several searches and can find no answer to this. The discussion at OSGI - handling 3rd party JARs required by a bundle helps somewhat, but does not fully answer my question. I have obtained a jar file, rabbitmq-client.jar, that is already packaged as an OSGi bundle (with Bundle-Name and other such properties in its MANIFEST.MF), that I would like to install as a bundle. This jar imports packages org.apache.commons.io and org.apache.commons.io.input from commons-io-1.2.jar. The RabbitMQ client 2.7.1 distribution also includes commons-cli-1.1.jar, so I presume that it is required as well. I examined the manifests of these commons jars and found that they do not appear to be packaged as bundles. That is, their manifests have none of the standard bundle properties. My specific question is: if I install rabbitmq-client.jar as a bundle, what is the proper way to get access to the packages that it needs to import from the commons jars? There are only three alternatives that I can think of, without rebuilding rabbitmq-client.jar. The packages from the commons jars are already included in the Equinox global classpath, and rabbitmq-client.jar will get them automatically from there. I must make another bundle with the two commons jars, export the needed packages, and install that bundle in Equinox. I must put these two commons jars in the global classpath when I start Equinox, and they will be available to rabbitmq-client.jar from there. I have read that one normally does not use the global classpath in an OSGi container. I am not clear on whether items from the global classpath are even available when building individual bundle classpaths. However, I note that rabbitmq-client.jar also imports other packages such as javax.net, which I presume come from the global classpath. Or is there some other bundle that exports them? Thanks for any assistance!

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