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  • Html.ListBox() and MultiselectList

    - by Ivan90
    Hi guys, I've a little problem with an Html.ListBox! I am developing a personal blog in ASP.NET MVC 1.0 and I created an adminpanel where I can add and edit a post! During this two operations, I can add also tags! I think of use an Html.ListBox() helper to list all tags, and so I can select multiple tags to add in a post! The problem isn't during the add mode, but in the edit mode, where I have to pre-select post's tags! I read that I have to use a MultiSelectList and so in its constructor pass, tags' list and tag's list(pre-selected value). But I don't know how to use this class! I post, some code: This is my models method that get all list tags in selectlist public IEnumerable<SelectListItem> GetTagsListBox() { return from t in db.Tags orderby t.IDTag descending select new SelectListItem { Text = t.TagName, Value = t.IDTag.ToString(), }; } So in Edit (Get and Post), Add(Get and Post) I use a ViewData to pass this list in Html.ListBox(). ViewData["Tags"] = tagdb.GetTagsListBox(); And in my view <%=Html.ListBox("Tags",ViewData["Tags"] as SelectList) %> So with this code it's ok in Add Mode! But in Edit Mode I need to pre-select those values! So Now, of course I have to create a method that get all tagsbypostid! and then in ViewData what Must I to pass? Any suggest?

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  • Erlang ODBC parameter query with null parameters

    - by Schlomer
    Is it possible to pass null values to parameter queries? For example Sql = "insert into TableX values (?,?)". Params = [{sql_integer, [Val1]}, {sql_float, [Val2]}]. % Val2 may be a float, or it may be the atom, undefined odbc:param_query(OdbcRef, Sql, Params). Now, of course odbc:param_query/3 is going to complain if Val2 is undefined when trying to match to a sql_float, but my question is... Is it possible to use a parameterized query, such as: Sql = "insert into TableY values (?,?,?,?,?,?,?,?,?)". with any null parameters? I have a use case where I am dumping a large number of real-time data into a database by either inserting or updating. Some of the tables I am updating have a dozen or so nullable fields, and I do not have a guarantee that all of the data will be there. Concatenating a SQL together for each query, checking for null values seems complex, and the wrong way to do it. Having a parameterized query for each permutation is simply not an option. Any thoughts or ideas would be fantastic! Thank you!

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  • JUnit Test method with randomized nature

    - by Peter
    Hey, I'm working on a small project for myself at the moment and I'm using it as an opportunity to get acquainted with unit testing and maintaining proper documentation. I have a Deck class with represents a deck of cards (it's very simple and, to be honest, I can be sure that it works without a unit test, but like I said I'm getting used to using unit tests) and it has a shuffle() method which changes the order of the cards in the deck. The implementation is very simple and will certainly work: public void shuffle() { Collections.shuffle(this.cards); } But, how could I implement a unit test for this method. My first thought was to check if the top card of the deck was different after calling shuffle() but there is of course the possibility that it would be the same. My second thought was to check if the entire order of cards has changed, but again they could possibly be in the same order. So, how could I write a test that ensures this method works in all cases? And, in general, how can you unit test methods for which the outcome depends on some randomness? Cheers, Pete

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  • Advantages of Using Linux as primary developer desktop

    - by Nick N
    I want to get some input on some of the advantages of why developers should and need to use Linux as their primary development desktop on a daily basic as opposed to using Windows. This is particulary helpful when your Dev, QA, and Production environments are Linux. The current analogy that I keep coming back to is. If I build my demo car as a Ford Escort, but my project car is a Ford Mustang, it doesn't make sense at all. I'm currently at an IT department that allows dual boot with Windows and Linux, but some run Linux while the vast majority use Windows. Here's several advantages that I've came up with since using Linux as a primary desktop. Same Exact operating system as Dev, QA, and Production Same Scripts (.sh) instead of maintaining (.bat and *.sh). Somewhat mitigated by using cygwin, but still a bit different. Team learns simple commands such as: cd, ls, cat, top Team learns Advanced commands like: pkill, pgrep, chmod, su, sudo, ssh, scp Full access to installs typically for Linux, such as RPM, DEB installs just like the target environments. The list could go on and on, but I want to get some feedback of anything that I may have missed, or even any disadvantages (of course there are some). To me it makes sense to migrate an entire team over to using Linux, and using Virtual Box, running Windows XP VM's to test functional items that 95% of most of the world uses. This is similar but a little different thread going on here as well. link text

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  • Put together tiles in android sdk and use as background

    - by Jon
    In a feeble attempt to learn some Android development am I stuck at graphics. My aim here is pretty simple: Take n small images and build a random image, larger than the screen with possibility to scroll around. Have an animated object move around on it I have looked at the SDK examples, Lunar Lander especially but there are a few things I utterly fail to wrap my head around. I've got a birds view plan (which in my head seems reasonably sane): How do I merge the tiles into one large image? The background is static so I figure I should do like this: Make a 2d array with refs to the tiles Make a large Drawable and draw the tiles on it At init draw this big image as the background At each onDraw redraw the background of the previous spot of the moving object, and the moving object at its new location The problem is the hands on things. I load the small images with "Bitmap img1 = BitmapFactory.decodeResource (res, R.drawable.img1)", but then what? Should I make a canvas and draw the images on it with "canvas.drawBitmap (img1, x, y, null);"? If so how to get a Drawable/Bitmap from that? I'm totally lost here, and would really appreciate some hands on help (I would of course be grateful for general hints as well, but I'm primarily trying to understand the Graphics objects). To make you, dear reader, see my level of confusion will I add my last desperate try: Drawable drawable; Canvas canvas = new Canvas (); Bitmap img1 = BitmapFactory.decodeResource (res, R.drawable.img1); // 50 x 100 px image Bitmap img2 = BitmapFactory.decodeResource (res, R.drawable.img2); // 50 x 100 px image canvas.drawBitmap (img1, 0, 0, null); canvas.drawBitmap (img2, 50, 0, null); drawable.draw (canvas); // obviously wrong as draw == null this.setBackground (drawable); Thanks in advance

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  • Haskell: "how much" of a type should functions receive? and avoiding complete "reconstruction"

    - by L01man
    I've got these data types: data PointPlus = PointPlus { coords :: Point , velocity :: Vector } deriving (Eq) data BodyGeo = BodyGeo { pointPlus :: PointPlus , size :: Point } deriving (Eq) data Body = Body { geo :: BodyGeo , pict :: Color } deriving (Eq) It's the base datatype for characters, enemies, objects, etc. in my game (well, I just have two rectangles as the player and the ground right now :p). When a key, the characters moves right, left or jumps by changing its velocity. Moving is done by adding the velocity to the coords. Currently, it's written as follows: move (PointPlus (x, y) (xi, yi)) = PointPlus (x + xi, y + yi) (xi, yi) I'm just taking the PointPlus part of my Body and not the entire Body, otherwise it would be: move (Body (BodyGeo (PointPlus (x, y) (xi, yi)) wh) col) = (Body (BodyGeo (PointPlus (x + xi, y + yi) (xi, yi)) wh) col) Is the first version of move better? Anyway, if move only changes PointPlus, there must be another function that calls it inside a new Body. I explain: there's a function update which is called to update the game state; it is passed the current game state, a single Body for now, and returns the updated Body. update (Body (BodyGeo (PointPlus xy (xi, yi)) wh) pict) = (Body (BodyGeo (move (PointPlus xy (xi, yi))) wh) pict) That tickles me. Everything is kept the same within Body except the PointPlus. Is there a way to avoid this complete "reconstruction" by hand? Like in: update body = backInBody $ move $ pointPlus body Without having to define backInBody, of course.

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  • substitution cypher with different alphabet length

    - by seanizer
    I would like to implement a simple substitution cypher to mask private ids in URLs I know how my IDs will look like (combination of upperchase ascii, digits and underscore), and they will be rather long, as they are composed keys. I would like to use a longer alphabet to shorten the resulting codes (I'd like to use upper and lower case ascii letters, digits and nothing else). So my incoming alphabet would be [A-Z0-9_] (37 chars) and my outgoing alphabet would be [A-Za-z0-9] (62 chars) so a compression of almost 50% would be available. let's say my URLs look like this: /my/page/GFZHFFFZFZTFZTF_24_F34 and I want them to look like this instead: /my/page/Ft32zfegZFV5 Obviously both arrays would be shuffled to bring some random order in. This does not have to be secure. if someone figures it out: fine, but I don't want the scheme to be obvious. My desired solution would be to convert the string to an integer representation of radix 37, convert the radix to 62 and use the second alphabet to write out that number. is there any sample code available that does something similar? Integer.parseInt ( http://java.sun.com/javase/6/docs/api/java/lang/Integer.html#parseInt%28java.lang.String,%20int%29 ) has some similar logic, but it is hard-coded to use standard digit behavior Any hints? I am using java to implement this but code or pseudo-code in any other language is of course also helpful

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  • Looking for combinations of server and embedded database engines

    - by codeelegance
    I'm redesigning an application that will be run as both a single user and multiuser application. It is a .NET 2.0 application. I'm looking for server and embedded databases that work well together. I want to deploy the embedded database in the single user setup and of course, the server in the multiuser setup. Past releases have been based on MSDE but in the past year we've been having a lot of install issues: new installs hanging and leaving the system in an unknown state, upgrades disconnecting the database, etc. I migrated the application to SQL Server 2005 and the install is more reliable (as long as a user doesn't try to install over a broken MSDE installation). Since next year's release will be a complete redesign I figured now's the best time to address the database issue as well. The database has been abstracted from the rest of the application so I just need to choose which database(s) to use and write an implementation for each one. So far I've considered: SQL Server/ SQL Server Compact Edition Firebird (same DB engine is available in two different server modes and an embedded dll) Each has its own merits but I'm also interested in any other suggestions. This is a fairly simple program and its data requirements are simple as well. I don't expect it to strain whatever database I eventually choose. So easy configuration and deployment hold more weight than performance.

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  • Using git filter-branch to remove commits by their commit message

    - by machineghost
    In our repository we have a convention where every commit message starts with a certain pattern: Redmine #555: SOME_MESSAGE We also do a bit of rebasing to bring in the potential release branch's changes to a specific issue's branch. In other words, I might have branch "foo-555", but before I merge it in to branch "pre-release" I need to get any commits that pre-release has that foo-555 doesn't (so that foo-555 can fast-forward merge in to pre-release). However, because pre-release sometimes changes, we sometimes wind up with situations where you bring in a commit from pre-release, but then that commit later gets removed from pre-release. It's easy to identify commits that came from pre-release, because the number from their commit message won't match the branch number; for instance, if I see "Redmine #123: ..." in my foo-555 branch, I know that its not a commit from my branch. So now the question: I'd like to remove all of the commits that "don't belong" to a branch; in other words, any commit that: Is in my foo-555 branch, but not in the pre-release branch (pre-release..foo-555) Has a commit message that doesn't start with "Redmine #555" but of course "555" will vary from branch to branch. Is there any way to use filter-branch (or any other tool) to accomplish this? Currently the only way I can see to do it is to do go an interactive rebase ("git rebase -i") and manually remove all the "bad" commits.

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  • Python virtualenv questions

    - by orokusaki
    I'm using VirtualEnv on Windows XP. I'm wondering if I have my brain wrapped around it correctly. I ran virtualenv ENV and it created C:\WINDOWS\system32\ENV. I then changed my PATH variable to include C:\WINDOWS\system32\ENV\Scripts instead of C:\Python27\Scripts. Then, I checked out Django into C:\WINDOWS\system32\ENV\Lib\site-packages\django-trunk, updated my PYTHON_PATH variable to point the new Django directory, and continued to easy_install other things (which of course go into my new C:\WINDOWS\system32\ENV\Lib\site-packages directory). I understand why I should use VirtualEnv so I can run multiple versions of Django, and other libraries on the same machine, but does this mean that to switch between environments I have to basically change my PATH and PYTHON_PATH variable? So, I go from developing one Django project which uses Django 1.2 in an environment called ENV and then change my PATH and such so that I can use an environment called ENV2 which has the dev version of Django? Is that basically it, or is there some better way to automatically do all this (I could update my path in Python code, but that would require me to write machine-specific code in my application)? Also, how does this process compare to using VirtualEnv on Linux (I'm quite the beginner at Linux).

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  • A question about writing a background/automatic/silent downloader/installer for an app in C#.

    - by Mike Webb
    Background: I have a main application that needs to be able to go to the web and download DLL files associated with it (ones that we write, located on our server). It really needs to be able to download these DLL files to the application folder in "C:\Program Files\". In the past I have used System.Net.WebClient to download whatever files I wanted from the web. The Issue I have had a lot of trouble downloading data in the past and saving to files on a user's hard drive. I get many reports of users saying that this does not work and it is generally because of user rights issues in the program. In the cases where it was an issue with program user rights every user could go to the exact file location on the web, download it, and then save it to the right place manually. I want this to work like all the other programs I have seen download/install in this fassion (i.e. Firefox Pluign Updates, Flash Player, JAVA, Adobe Reader, etc). All of these work without a hitch. The Question Is there some code I need to use to give my downloader program special rights to the Program Files folder? Can I even do this? Is there a better class or library that I should use? Is there a different approach to downloading files I should take, such as using threads or something else to download data? Any help here is appreciated. I want to try to stay away from third-party apps/libraries if at all possible, other than Microsoft of course, due to licensing issues, but still send any suggestions my way. Again, other programs seem to have the rights issues and download capability figured out. I want this same capability.

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  • Trigger ad-hoc activity within a workflow

    - by Chris Taylor
    I am looking to use WF 4 to replace an existing workflow solution we have. One feature that is currently used in the existing workflow engine is the ability to cancel a current activity and loopback to a FlowSwitch type activity. So given the following crude workflow where we start at 'O' and base in the input data the workflow follows the path to 'A2' which is currently blocking on s bookmark waiting for input. ---------A1--\ | \ /\ \ O------- ---->--(A2)-------| ^ \/ / | | | / | | ---------A3--/ | | | |----------------------| However in the meantime some out of band data comes in that means we should cancel 'A2' and return to the FlowSwitch to re-evaluate based on the new data. The question is what is the best way to handle the out of band data that arrived? My initial guess is to have a Parallel activity with one branch waiting for out of band data and the other branch containing the workflow sequence described above. If data came in on the brach waiting for the out of band data, how would I cancel the current activity in the workflow and force it to return to the FlowSwitch. Or of course is there a better way to handle this. I have not actually done any work with the WF4 stuff for WF3 for that matter so I might be missing something obvious here.

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  • Load SQL query result data into cache in advance

    - by Marc
    I have the following situation: .net 3.5 WinForm client app accessing SQL Server 2008 Some queries returning relatively big amount of data are used quite often by a form Users are using local SQL Express and restarting their machines at least daily Other users are working remotely over slow network connections The problem is that after a restart, the first time users open this form the queries are extremely slow and take more or less 15s on a fast machine to execute. Afterwards the same queries take only 3s. Of course this comes from the fact that no data is cached and must be loaded from disk first. My question: Would it be possible to force the loading of the required data in advance into SQL Server cache? Note My first idea was to execute the queries in a background worker when the application starts, so that when the user starts the form the queries will already be cached and execute fast directly. I however don't want to load the result of the queries over to the client as some users are working remotely or have otherwise slow networks. So I thought just executing the queries from a stored procedure and putting the results into temporary tables so that nothing would be returned. Turned out that some of the result sets are using dynamic columns so I couldn't create the corresponding temp tables and thus this isn't a solution. Do you happen to have any other idea?

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  • Which are the RDBMS that minimize the server roundtrips? Which RDBMS are better (in this area) than

    - by user193655
    When the latency is high ("when pinging the server takes time") the server roundtrips make the difference. Now I don't want to focus on the roundtrips created in programming, but the roundtrips that occur "under the hood" in the DB engine, so the roundtrips that are 100% dependant on how the RDBMS is written itself. I have been told that FireBird has more roundtrips than MySQL. But this is the only information I know. I am currently supporting MS SQL but I'd like to change RDBMS (because I use Express Editions and in my scenario they are quite limiting from the performance point of view), so to make a wise choice I would like to include also this point into "my RDBMS comparison feature matrix" to understand which is the best RDBMS to choose as an alternative to MS SQL. So the bold sentence above would make me prefer MySQL to Firebird (for the roundtrips concept, not in general), but can anyone add informations? And MS SQL where is it located? Is someone able to "rank" the roundtrip performance of the main RDBMS, or at least: MS SQL, MySql, Postegresql, Firebird (I am not interested in Oracle since it is not free, and if I have to change I would change to a free RDBMS). Anyway MySql (as mentioned several times on stackoverflow) has a not clear future and a not 100% free license. So my final choice will probably dall on PostgreSQL or Firebird. Additional info: somehow you can answer my question by making a simple list like: MSSQL:3; MySQL:1; Firebird:2; Postgresql:2 (where 1 is good, 2 average, 3 bad). Of course if you can post some links where the roundtrips per RDBMSs are compared it would be great

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  • Modeling complex hierarchies

    - by jdn
    To gain some experience, I am trying to make an expert system that can answer queries about the animal kingdom. However, I have run into a problem modeling the domain. I originally considered the animal kingdom hierarchy to be drawn like -animal -bird -carnivore -hawk -herbivore -bluejay -mammals -carnivores -herbivores This I figured would allow me to make queries easily like "give me all birds", but would be much more expensive to say "give me all carnivores", so I rewrote the hierarchy to look like: -animal -carnivore -birds -hawk -mammals -xyz -herbivores -birds -bluejay -mammals But now it will be much slower to query "give me all birds." This is of course a simple example, but it got me thinking that I don't really know how to model complex relationships that are not so strictly hierarchical in nature in the context of writing an expert system to answer queries as stated above. A directed, cyclic graph seems like it could mathematically solve the problem, but storing this in a relational database and maintaining it (updates) would seem like a nightmare to me. I would like to know how people typically model such things. Explanations or pointers to resources to read further would be acceptable and appreciated.

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  • Close TCP connection when owner process is already killed

    - by Otiel
    I have a Windows service that - when it starts - opens some WCF services to listen on the 8000 port. It happens that this service crashes sometimes. When it does, the TCP connection is not released, thus causing my service to throw an exception if I try to start it again: AddressAlreadyInUseException: There is already a listener on IP endpoint 0.0.0.0:8000 Some observations: When running CurrPorts or netstat -ano, I can see that the 8000 port is still in use (in LISTENING state) and is owned by the Process ID XXX that corresponded to my service process ID. But my service has already crashed, and does not appear in the Task Manager anymore. Thus I can't kill the process to free the port! Of course, running taskkill /PID XXX returns: ERROR: The process "XXX" not found. When running CurrPorts or netstat -b, I can see that the process name involved in creating the listening port is System, and not as MyService.exe (whereas it is MyService.exe when my service is running). I tried to use CurrPorts to close the connection, but I always get the following error message: Failed to close one or more TCP connections. Be aware that you must run this tool as admin in order to close TCP connections. (Useless to say, I do run CurrPorts as Administrator...) TCPView is not much help either: the process name associated to the 8000 port is <non-existent>, and doing "End process" or "Close connection" has no effect. I tried to see if there was not a child process associated with the PID XXX using Process Explorer, but no luck here. If I close my service properly (before it crashes), the TCP connection is correctly released. This is normal, as I close the WCF service hosts in the OnStop() event of my service. The only way I found to release the connection is to restart the server (which is not convenient in a production environment as you can guess). Waiting does not help, the TCP connection is never released. How can I close the connection without restarting the Windows server? PS: found some questions extremely similar to mine.

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  • IIS Restrict Access to Directory for table of users

    - by Dave
    I am trying to restrict access to files in a directory and it's sub directories based user rights. My user rights are stored in an MS SQL database in a custom format, however it is easy to query the list of users with rights to this directory. I need to know how to apply this to a web config on the server to authenticate against a query of a database table to determine if the username is authenticated and allowed to view the file. Of course if they are not they should be blocked / given a 404. I am using IIS and ASP.Net MVC3 with a form based security as opposed to the built in roles and responsibilities that was custom made for us and that works great. There are over 10k users tied to this non-Active Directory authentication so I am not planning to change my authentication type so please don't go there. It is not my decision on the choice of platform, or I would have gone with a LAMP server and been done with this. Edit 11-13-2012 @ 8:57a: In the web config can you put the result of an SQL query?

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  • Choose a XML node in SQL Server based on max value of a child element

    - by Jay
    I am trying to select from SQL Server 2005 XML datatype some values based on the max data that is located in a child node. I have multiple rows with XML similar to the following stored in a field in SQL Server: <user> <name>Joe</name> <token> <id>ABC123</id> <endDate>2013-06-16 18:48:50.111</endDate> </token> <token> <id>XYX456</id> <endDate>2014-01-01 18:48:50.111</endDate> </token> </user> I want to perform a select from this XML column where it determines the max date within the token element and would return the datarows similar to the result below for each record: Joe XYZ456 2014-01-01 18:48:50.111 I have tried to find a max function for xpath that would all me to select the correct token element but I couldn't find one that would work. I also tried to use the SQL MAX function but I wasn't able to get it working with that method either. If I only have a single token it of course works fine but when I have more than one I get a NULL, most likely because the query doesn't know which date to pull. I was hoping there would be a way to specify a where clause [max(endDate)] on the token element but haven't found a way to do that. Here is an example of the one that works when I only have a single token: SELECT XMLCOL.query('user/name').value('.','NVARCHAR(20)') as name XMLCOL.query('user/token/id').value('.','NVARCHAR(20)') as id XMLCOL.query('user/token/endDate').value(,'xs:datetime(.)','DATETIME') as endDate FROM MYTABLE

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  • Can I add a portrait layout on top of a landscape Camera SurfaceView?

    - by Uwe Krass
    My application should hold a camera preview surface. The camera is fixed to landscape view via AndroidMainfest.xml <application android:icon="@drawable/icon" android:label="Camera"> <uses-library android:name="com.google.android.maps" /> <uses-feature android:name="android.hardware.camera" /> <uses-feature android:name="android.hardware.camera.autofocus" /> <activity android:name=".CameraPreview" android:label="Camera" android:screenOrientation="landscape"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> If there is another way to get the camera preview itself to behave correctly, please let me know. Now I need to have an overlay that holds a bunch of buttons. Due to usability, the user interface should be set to portrait view (or even better orientation aware). Is there a way to have a transparent layout (for buttons and other GUI elements) in portrait orientation? I tried to write a special rotated layout by extending a RelativeLayout, but the onDraw method isn't called at anytime. public class RotatedOverlay extends RelativeLayout { private static final String TAG = "RotatedOverlay"; public RotatedOverlay(Context context, AttributeSet attrs ) { super(context, attrs); } @Override protected void onDraw(Canvas canvas) { canvas.rotate(90); super.onDraw(canvas); } I am quite new to the Android plattform programming. Of course I dont know much about the programming tricks and workarounds yet. I did a lot of research over the last two weeks (even studied the native Camera implementation), but couldnt find a good solution so far. Maybe it works with two seperate Activities, but I dont think, that this can the right solution.

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  • LGPL library with plugins of varied licenses

    - by Chris
    Note: "Plugins" here refers to shared objects that are accessed via dlopen() and friends. I'm writing a library that I'm planning on releasing under the LGPL. Its functionality can be extended (supporting new audio file formats, specifically) through plugins. I'm planning on creating an exception to the LGPL for this library so that plugins can be released under any license. So far so good. I've written a number of plugins already, some of which use LGPL and some of which use GPL libraries. I'm wary of releasing them with the main library, however, due to licensing issues. The LGPL-based ones would generally be fine, but for my "any license" clause. Would distributing these LGPL-based plugins with the library require the consent of the other license holders to create this exception? Along the same lines, would the inclusion of GPL-based plugins with my library force the whole thing to go GPL? I could also release the plugins separately. The advantage, I presume, is that the plugins an d library will now not be distributed together, creating more separation. But this seems to be no different, really, in the end. Boiled down: Can I include, with my LGPL library, plugins of varied licenses? If not, is it really any different releasing them separately? And if so, there's no real need to create an exception for non-LGPL plugins, is there? It's LGPL or nothing. I'd prefer asking a lawyer, of course, but this is just a hobby and I can't afford to hire a lawyer when I don't expect or want monetary compensation. I'm just hoping others have been in similar situations and have insight.

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  • C# Hiding, overriding and calling function from base class.

    - by Lukasz Lysik
    I'm learning C# and I encountered the following problem. I have two classes: base and derived: class MyBase { public void MyMethod() { Console.WriteLine("MyBase::MyMethod()"); } } class MyDerived: MyBase { public void MyMethod() { Console.WriteLine("MyDerived::MyMethod()"); } } For now, without virtual and override key words. When I compile this I get the warning (which is of course expected) that I try to hide MyMethod from MyBase class. What I want to do is to call the method from the base class having an instance of derived class. I do this like this: MyDerived myDerived = new MyDerived(); ((MyBase)myDerived).MyMethod(); It works fine when I do not specify any virtual, etc. keywords in the methods. I tried to put combination of the keywords and I got the following results: | MyBase::MyMethod | MyDerived::MyMethod | Result printed on the console | | -----------------|---------------------|-------------------------------| | - | - | MyBase::MyMethod() | | - | new | MyBase::MyMethod() | | virtual | new | MyBase::MyMethod() | | virtual | override | MyDerived::MyMethod() | I hope the table is clear to you. I have two questions: Is it the correct way to call the function from the base class (((MyBase)myDerived).MyMethod();)? I know about base keyword, but it can be called only from the inside of the derived class. Is it right? Why in the last case (with virtual and override modifiers) the method which was called came from the derived class? Would you please explain that?

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  • What's the best NAME for "quick" Category you add to a file?

    - by Joe Blow
    So the other day I was sick of typing out repetetive addTarget:action:forControlEvents:s, and macros are only entertaining for so long, so I did this: @implementation UIControl (xx) -(void)addTarget:(id)target action:(SEL)action { [self addTarget:target action:action forControlEvents:UIControlEventTouchUpInside]; } @end *and simply added it at the top of the .m file in question. Works great of course, but notice the "xx".* What's the best thing to NAME a "quick" Category like this? Annoyingly, it appears you can not leave the xx blank - it would then become an "Extension" (which, incidentally, I don't understand at all). I was thinking maybe: a single underscore the name of the class again identically "quick" perhaps the name of the class in this file (as in "quick extra routines for UIControl in CherryBomb") - so it would be UIControl(CherryBomb), ie, remind you that these extra routines are handy for CherryBomb "x" your or your company's initials (use the same "quick" Category name everywhere) "ThisTextNeverUsedAnywhere" By the way, I've been assuming that Categories only happen in the files that see them (CherryBomb.m in the example) - they do not from then on apply app-wide. ie they only apply where you include the header file (UIControl+NattyStuff) or in the "quick" case only in the file to which one adds the text. (By the way ... it appears you do not actually need to include an interface for such a Category, i.e. you can omit... //you can actually get away without these lines... //#import <UIKit/UIControl.h> //@interface UIControl (x) //-(void)addTarget:(id)target action:(SEL)action; //@end ... that part and it works fine.) For people who love Categories, and who doesn't, what's the answer to this troubling question? What should you name a "quick" Category where the name is never going to be referenced again and is irrelevant? Is "_" a solution?

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  • An Ideal Keyboard Layout for Programming

    - by Jon Purdy
    I often hear complaints that programming languages that make heavy use of symbols for brevity, most notably C and C++ (I'm not going to touch APL), are difficult to type because they require frequent use of the shift key. A year or two ago, I got tired of it myself, downloaded Microsoft's Keyboard Layout Creator, made a few changes to my layout, and have not once looked back. The speed difference is astounding; with these few simple changes I am able to type C++ code around 30% faster, depending of course on how hairy it is; best of all, my typing speed in ordinary running text is not compromised. My questions are these: what alternate keyboard layouts have existed for programming, which have gained popularity, are any of them still in modern use, do you personally use any altered layout, and how can my layout be further optimised? I made the following changes to a standard QWERTY layout. (I don't use Dvorak, but there is a programmer Dvorak layout worth mentioning.) Swap numbers with symbols in the top row, because long or repeated literal numbers are typically replaced with named constants; Swap backquote with tilde, because backquotes are rare in many languages but destructors are common in C++; Swap minus with underscore, because underscores are common in identifiers; Swap curly braces with square brackets, because blocks are more common than subscripts; and Swap double quote with single quote, because strings are more common than character literals. I suspect this last is probably going to be the most controversial, as it interferes the most with running text by requiring use of shift to type common contractions. This layout has significantly increased my typing speed in C++, C, Java, and Perl, and somewhat increased it in LISP and Python.

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  • Nested Class member function can't access function of enclosing class. Why?

    - by Rahul
    Please see the example code below: class A { private: class B { public: foobar(); }; public: foo(); bar(); }; Within class A & B implementation: A::foo() { //do something } A::bar() { //some code foo(); //more code } A::B::foobar() { //some code foo(); //<<compiler doesn't like this } The compiler flags the call to foo() within the method foobar(). Earlier, I had foo() as private member function of class A but changed to public assuming that B's function can't see it. Of course, it didn't help. I am trying to re-use the functionality provided by A's method. Why doesn't the compiler allow this function call? As I see it, they are part of same enclosing class (A). I thought the accessibility issue for nested class meebers for enclosing class in C++ standards was resolved. How can I achieve what I am trying to do without re-writing the same method (foo()) for B, which keeping B nested within A? I am using VC++ compiler ver-9 (Visual Studio 2008). Thank you for your help.

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  • SQL Query Math Gymnastics

    - by keruilin
    I have two tables of concern here: users and race_weeks. User has many race_weeks, and race_week belongs to User. Therefore, user_id is a fk in the race_weeks table. I need to perform some challenging math on fields in the race_weeks table in order to return users with the most all-time points. Here are the fields that we need to manipulate in the race_weeks table. races_won (int) races_lost (int) races_tied (int) points_won (int, pos or neg) recordable_type(varchar, Robots can race, but we're only concerned about type 'User') Just so that you fully understand the business logic at work here, over the course of a week a user can participate in many races. The race_week record represents the summary results of the user's races for that week. A user is considered active for the week if races_won, races_lost, or races_tied is greater than 0. Otherwise the user is inactive. So here's what we need to do in our query in order to return users with the most points won (actually net_points_won): Calculate each user's net_points_won (not a field in the DB). To calculate net_points, you take (1000 * count_of_active_weeks) - sum(points__won). (Why 1000? Just imagine that every week the user is spotted a 1000 points to compete and enter races. We want to factor-out what we spot the user because the user could enter only one race for the week for 100 points, and be sitting on 900, which we would skew who actually EARNED the most points.) This one is a little convoluted, so let me know if I can clarify further.

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