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• Database Design: A proper table design for large number of column values.

  - by Jake

  I wish to perform an experiment many different times. After every trial, I am left with a "large" set of output statistics -- let's say, 1000. I would like to store the outputs of my experiments in a table, but what's the best way...? Option 1 Have a table with 1000 columns. Seems like a bad idea. What if the number of statistics one day exceeds the maximum number of columns? Option 2 Have a table with three columns. Let's say, ID, StatisticType, and StatisticValue. That way, you can have as many statistics as you want. However, reading a single experiments statistics becomes more complicated. Moreover, what if different statistics are different data types?? Any suggestions?

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• What if I put two kinds of encoded strings, say utf-8 and utf-16, in one file?

  - by jonny

  In Python, for example: f = open('test','w') f.write('this is a test\n'.encode('utf-16')) f.write('another test\n'.encode('utf-8')) f.close() That file gets messy when I re-open it: f = open("test") print f.readline().decode('utf-16') # it leads to UnicodeDecodeError print f.readline().decode('utf-8') # it works fine However if I keep the texts encoded in one style (say utf-16 only), it could read back ok. So I'm guessing mixing two types of encoding in the same file is wrong and couldn't be decoded back, even if I do know the encoding rules of each specific string? Any suggestion is welcome, thank you!

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• IEnumerable and IEnumerator in the same class, bad idea?

  - by David Rutten

  Is this a bad idea? Private Class GH_DataStructureEnumerator(Of Q As Types.IGH_Goo) Implements IEnumerable(Of Q) Implements IEnumerator(Of Q) .... .... 'Current, MoveNext, Reset etc.' .... .... Public Function GetEnumerator_Generic() As IEnumerator(Of Q) _ Implements IEnumerable(Of Q).GetEnumerator Return Me End Function End Class This class is only visible as an IEnumerable(Of T) readonly property, and it saves me an additional class that wraps IEnumerator(Of T). But somehow it just seems wrong. Is there a better way?

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• Puzzle: Overload a C++ function according to the return value

  - by Motti

  We all know that you can overload a function according to the parameters: int mul(int i, int j) { return i*j; } std::string mul(char c, int n) { return std::string(n, c); } Can you overload a function according to the return value? Define a function that returns different things according to how the return value is used: int n = mul(6, 3); // n = 18 std::string s = mul(6, 3); // s = "666" // Note that both invocations take the exact same parameters (same types) You can assume the first parameter is between 0-9, no need to verify the input or have any error handling.

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• Is a switch statement ok for 30 or so conditions?

  - by DeanMc

  I am in the final stages of creating an MP4 tag parser in .Net. For those who have experience with tagging music you would be aware that there are an average of 30 or so tags. If tested out different types of loops and it seems that a switch statement with Const values seems to be the way to go with regard to catching the tags in binary. The switch allows me to search the binary without the need to know which order the tags are stored or if there are some not present but I wonder if anyone would be against using a switch statement for so many conditionals. Any insight is much appreciated.

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• How does this "&" work in this statement?

  - by aquaibm

  I know how bitwise AND works,but I don't understand how does (sourceDragMask & NSDragOperationGeneric) work here,I don't get the point.Is there anyone can explain to me?Thanks a lot. (NSDragOperation)draggingEntered:(id )sender { NSPasteboard *pboard; NSDragOperation sourceDragMask; sourceDragMask = [sender draggingSourceOperationMask]; pboard = [sender draggingPasteboard]; if ( [[pboard types] containsObject:NSColorPboardType] ) { if (sourceDragMask & NSDragOperationGeneric) { return NSDragOperationGeneric; } } return NSDragOperationNone; }

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• Cherokee rule failover

  - by phretor

  I have a Cherokee virtual host configured as follows: 1st rule: "Directory /" -> HTTP Reverse Proxy 2nd rule: "Directory /" -> uWSGI I know the second rule is useless because it's never triggered. However, the first rule seldom returns a 504 Gateway Timeout error so I was thinking of failing over the second rule, yet I don't know how to achieve this. Is it possible? Unfortunately, I cannot use only one rule with load balanced information sources, because I use two different types of information sources (i.e., pure HTTP and WSGI).

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• Something like System.Diagnostics.Process.Start to run a stream

  - by phenevo

  Hi, I get from server images and videos by stream. Now I'm saving it: Stream str = client.GetFile(path); using (var outStream = new FileStream(@"c:\myFile.jpg", FileMode.Create)) { var buffer = new byte[4096]; int count; while ((count = str.Read(buffer, 0, buffer.Length)) > 0) { outStream.Write(buffer, 0, count); } } I can be jpg, mpg, flv and a lot of other multimedia types (Before I get stream I know what is a extension of this file). Now I want to not save it , bu run direct from stream. Is it possible ??

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• LINQ-to-XML to DataGridView: Cannot edit fields -- How to fix?

  - by Pretzel

  I am currently doing LINQ-to-XML and populating a DataGridView with my query just fine. The trouble I am running into is that once loaded into the DataGridView, the values appear to be Un-editable (ReadOnly). Here's my code: var barcodes = (from src in xmldoc.Descendants("Container") where src.Descendants().Count() > 0 select new { Id = (string)src.Element("Id"), Barcode = (string)src.Element("Barcode"), Quantity = float.Parse((string)src.Element("Quantity").Attribute("value")) }).Distinct(); dataGridView1.DataSource = barcodes.ToList(); I read somewhere that the "DataGridView will be in ReadOnly mode when you use Anonymous types." But I couldn't find an explanation why or exactly what to do about it. Any ideas?

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• Should I use implicit conversions to enforce preconditions?

  - by Malvolio

  It occurs to me that I could use use implicit conversions to both announce and enforce preconditions. Consider this: object NonNegativeDouble { implicit def int2nnd(d : Double) : NonNegativeDouble = new NonNegativeDouble(d) implicit def nnd2int(d : NonNegativeDouble) : Double = d.v def sqrt(n : NonNegativeDouble) : NonNegativeDouble = scala.math.sqrt(n) } class NonNegativeDouble(val v : Double ) { if (v < 0) { throw new IllegalArgumentException("negative value") } } object Test { def t1 = { val d : Double = NonNegativeDouble.sqrt(3.0); printf("%f\n", d); val n : Double = NonNegativeDouble.sqrt(-3.0); } } Ignore for the moment the actual vacuity of the example: my point is, the subclass NonNegativeDouble expresses the notion that a function only takes a subset of the entire range of the class's values. First is this: A good idea, a bad idea, or an obvious idea everybody else already knows about Second, this would be most useful with basic types, like Int and String. Those classes are final, of course, so is there a good way to not only use the restricted type in functions (that's what the second implicit is for) but also delegate to all methods on the underlying value (short of hand-implementing every delegation)?

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• Java's ThreadPoolExecutor equivalent for C#?

  - by chillitom

  Hi Guys, I used to make good use of Java's ThreadPoolExecutor class and have yet to find a good equivalent in C#. I know of ThreadPool.QueueUserWorkItem which is useful in many cases but no good if you want to control the number of threads assigned to a task or have multiple individual queues for different task types. For example I liked to use a ThreadPoolExecutor with a single thread to guarantee sequential execution of asynchronous calls.. Is there an easy way to do this in C#? Is there a non-static thread pool implementation? Thanks, T.

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• Again, what version control system to choose?

  - by Ivan

  Please excuse me for probably a newbie hundred-times-chewed question. I have no experience with version control systems except of using Visual Source Safe in a project done by 2 people sitting in front of each other (which has shown VSS quite sack of boulders, not anything useful). Right now I am looking to grok-in using some modern VCS. Here are the preferences in descending priority order: Platform-agnostic. Pretty pleasant to use With Visual Studio 2010 on Windows as well as With NetBeans 6.9 and Eclipse 3.6 on Linux and Mac. Convenient and efficient for mutually-dependent projects done by teams of 1-10 and consisting of files of quite a diverse selection of types. Including early-stage projects with unstable design and experimenting. Modern. As fresh and future-technology-feature-rich as possible. Free & open-source. Should I take a closer look at SVN, Mercurial, GIT, Bazaar, or something else?

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• MPI4Py Scatter sendbuf Argument Type?

  - by Noel

  I'm having trouble with the Scatter function in the MPI4Py Python module. My assumption is that I should be able to pass it a single list for the sendbuffer. However, I'm getting a consistent error message when I do that, or indeed add the other two arguments, recvbuf and root: File "code/step3.py", line 682, in subbox_grid i = mpi_communicator.Scatter(station_range, station_data) File "Comm.pyx", line 427, in mpi4py.MPI.Comm.Scatter (src/ mpi4py_MPI.c:44993) File "message.pxi", line 321, in mpi4py.MPI._p_msg_cco.for_scatter (src/mpi4py_MPI.c:14497) File "message.pxi", line 232, in mpi4py.MPI._p_msg_cco.for_cco_send (src/mpi4py_MPI.c:13630) File "message.pxi", line 36, in mpi4py.MPI.message_simple (src/ mpi4py_MPI.c:11904) ValueError: message: expecting 2 or 3 items Here is the relevant code snipped, starting a few lines above 682 mentioned above. for station in stations #snip--do some stuff with station station_data = [] station_range = range(1,len(station)) mpi_communicator = MPI.COMM_WORLD i = mpi_communicator.Scatter(station_range, nsm) #snip--do some stuff with station[i] nsm = combine(avg, wt, dnew, nf1, nl1, wti[i], wtm, station[i].id) station_data = mpi_communicator.Gather(station_range, nsm) I've tried a number of combinations initializing station_range, but I must not be understanding the Scatter argument types properly. Does a Python/MPI guru have a clarification this?

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• does adding static library need xcode project of static library for linking?

  - by mirdad

  I have seen some static library projects in iOS.I see two different types of linking static library. 1)adding .a static library to new xcode project and its header files only. 2)adding .a static library to new xcode project and adding the xcode project through which static library has created. when I remove the the xcode project through which static library has created from the 2nd project, it gives error.I tried first approach for 2nd one.But it is not working. Can you please explain why it is differed? Will it be differed by the xcode versions we use? is The second approach for old xcode versions?

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• PHP specifying a fixed include source for scripts in different directories

  - by Extrakun

  I am currently doing unit testing, and use folders to organize my test cases. All cases pertaining to managing of user accounts, for example, go under \tests\accounts. Over time, there are more test cases, and I begin to seperate the cases by types, such as \tests\accounts\create, \tests\account\update and etc. However, one annoying problem is I have to specify the path to a set of common includes. I have to use includes like this: include_once ("../../../../autoload.php"); include_once ("../../../../init.php"); A test case in tests\accounts\ would require change to the include (one less directory level down). Is there anyway to have them somehow locating my two common includes? I understand I could set include paths within my PHP's configurations, or use server environment variables, but I would like to avoid such solutions as they make the application less portable and coupled with another layer which the programmer can't control (some web-host doesn't allow configuration of PHP's configuration settings, for example)

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• design using a readonly class in c#

  - by edosoft

  Hi Small design question here. I'm trying to develop a calculation app in C#. I have a class, let's call it InputRecord, which holds 100s of fields (multi dimensional arrays) This InputRecordclass will be used in a number of CalculationEngines. Each CalculcationEngine can make changes to a number of fields in the InputRecord. These changes are steps needed for it's calculation. Now I don't want the local changes made to the InputRecord to be used in other CalculcationEngine's classes. The first solution that comes to mind is using a struct: these are value types. However I'd like to use inheritance: each CalculationEngine needs a few fields only relevant to that engine: it's has it's own InputRecord, based on BaseInputRecord. Can anyone point me to a design that will help me accomplish this?

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• Ignoring generated files when using "Treat warnings as errors"

  - by krystan honour

  We have started a new project but also have this problem for an existing project. The problem is that when we compile with a warning level of 4 we also want to switch on 'Treat all warnings as errors' We are unable to do this at the moment because generated files (in particular reference.cs files) are missing things like XML comments and this generates a warning, we do not want to suppress the xml comment warnings totally out of all files just for specific types of files (namely generated code). I have thought of a way this could be achieved but am not sure if these are the best way to do this or indeed where to start :) My thinking is that we need to do something with T4 templates for the code that is generated such that it does fill in XML documentation for generated code. Does anyone have any ideas, currently I'm at well over 2k warnings (its a big project) :(

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• iOS Facebook Access Token To Get User Wall Feed (status)

  - by Felix

  [DISCLAIMER : None of the access token or ID below here are real] I've done research for three solid days and no result on how to get user wall feed(post). I have used https://graph.facebook.com/oauth/access_token?client_id=YOUR_APP_ID&client_secret=YOUR_APP_SECRET&grant_type=client_credentials and get the access token which is something like this access_token=454345994651138|bAMGfuW-ueNXGCahley7ga125HN and then https://graph.facebook.com/100005939123542/feed?access_token=454345994651138|bAMGfuW-ueNXGCahley7ga125HN It gives me general information such as user's likes, name, id, current city... but NOT user's wall posts. I've learned that there are three types of access token, which is App Token, User Token, and Page Token. In order to get user/feed by using graphAPI, I need to request to get User Token, but there's NO information in the lousy Facebook Doc! (Which frustrated me the most!) In order to generate the user access token, we need to set some permission, generate the access token, and GET the user's wall feed, which is in JSON format. My question is : How do I get the User Access Token in order to get user wall post in iOS Xcode?

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• WCF - (Custom) binary serialisation.

  - by Barguast

  I want to be able to query my database over the web, and I am wanting to use a WCF service to handle the requests and results. The problem is that due to the amount of data that can potentially be returned from these queries, I'm worried about how these results will be serialised over the network. For example, I can imagine the XML serialisation looking like: <Results> <Person Name="Adam" DateOfBirth="01/02/1985" /> <Person Name="Bob" DateOfBirth="04/07/1986" /> </Results> And the binary serialisation containing types names and other (unnecessary) metadata. Perhaps even the type name for each element in a collection? o_o Ideally, I'd like to perform the serialisation of certain 'DataContract'-s myself so I can make it super-compact. Does anyone know if this is possible, or of any articles which explain how to do custom serialisation with WCF? Thanks in advance

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• Google analytics-style custom report builder UI

  - by gregmac

  I'm looking for a reporting engine/UI that can be integrated into a product, which has a UI along the lines of Google Analytics' Custom Reports builder. Is anyone aware of such a thing? The data is in our case is not page views/visitors/etc, but is similar in nature, in that there are limited entities or types of data, but each entity has many attributes/columns and many different ways of aggregating data (or in GA-style speak, metrics and dimensions). The analytics-style UI is very intuitive and allows many reports to be created in powerful ways, without having to know SQL. I have preference for a web-based tool (seeing that it is 2010 and this is a web app -- I mention only because it seems the vast majority of reporting tools still have only a non-web-based creation tool).

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• FileInputStream for a generic file System

  - by Akhil

  I have a file that contains java serialized objects like "Vector". I have stored this file over Hadoop Distributed File System(HDFS). Now I intend to read this file (using method readObject) in one of the map task. I suppose FileInputStream in = new FileInputStream("hdfs/path/to/file"); wont' work as the file is stored over HDFS. So I thought of using org.apache.hadoop.fs.FileSystem class. But Unfortunately it does not have any method that returns FileInputStream. All it has is a method that returns FSDataInputStream but I want a inputstream that can read serialized java objects like vector from a file rather than just primitive data types that FSDataInputStream would do. Please help!

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• Android EditText within a ListView

  - by metalideath

  I have created a custom Array Adapter to bind a custom row that contains some static text and an editable EditText. I am trying to register to be notified when the user changes the text within the edit text and when notified to determine which ArrayList row the modified EditText corresponds to. In the past with other types of views such as a Spinner I could simply put a reference to the parent view and the row number into the tag for the Spinner view. And then when I was notified that the value changed I read the tag to determine how to correlate it back to the master ArrayList. The problem with registering to be notifed with an EditText change is that you do not get back a view but instead get a TextWatcher and I have no way to correlate back to the parent view or ArrayList row. What is the technique that you need to use in this circumstance?

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• Worst side effects from chars signedness. (Explanation of signedness effects on chars and casts)

  - by JustSmith

  I frequently work with libraries that use char when working with bytes in C++. The alternative is to define a "Byte" as unsigned char but that not the standard they decided to use. I frequently pass bytes from C# into the C++ dlls and cast them to char to work with the library. When casting ints to chars or chars to other simple types what are some of the side effects that can occur. Specifically, when has this broken code that you have worked on and how did you find out it was because of the char signedness? Lucky i haven't run into this in my code, used a char signed casting trick back in an embedded systems class in school. I'm looking to better understand the issue since I feel it is relevant to the work I am doing.

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• Creating a method that is simultaneously an instance and class method

  - by Mike Axiak

  In Python, I'd like to be able to create a function that behaves both as a class function and an instance method, but with the ability to change behaviors. The use case for this is for a set of serializable objects and types. As an example: >>> class Thing(object): #... >>> Thing.to_json() 'A' >>> Thing().to_json() 'B' I know that given the definition of classmethod() in funcobject.c in the Python source, this looks like it'd be simple with a C module. Is there a way to do this from within python? Thanks!

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• UTF-8 conversion

  - by leachianus

  Hey guys, I am grabbing a JSON array and storing it in a NSArray, however it includes JSON encoded UTF-8 strings, for example pass\u00e9 represents passé. I need a way of converting all of these different types of strings into the actual character. I have an entire NSArray to convert. Or I can convert it when it is being displayed, which ever is easiest. I found this chart http://tntluoma.com/sidebars/codes/ is there a convenience method for this or a library I can download? thanks, BTW, there is no way I can find to change the server so I can only fix it on my end...

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