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  • How would you code an efficient Circular Buffer in Java or C#

    - by Cheeso
    I want a simple class that implements a fixed-size circular buffer. It should be efficient, easy on the eyes, generically typed. EDIT: It need not be MT-capable, for now. I can always add a lock later, it won't be high-concurrency in any case. Methods should be: .Add and I guess .List, where I retrieve all the entries. On second thought, Retrieval I think should be done via an indexer. At any moment I will want to be able to retrieve any element in the buffer by index. But keep in mind that from one moment to the next Element[n] may be different, as the Circular buffer fills up and rolls over. This isn't a stack, it's a circular buffer. Regarding "overflow": I would expect internally there would be an array holding the items, and over time the head and tail of the buffer will rotate around that fixed array. But that should be invisible from the user. There should be no externally-detectable "overflow" event or behavior. This is not a school assignment - it is most commonly going to be used for a MRU cache or a fixed-size transaction or event log.

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  • is it better to test if a function is needed inside or outside of it?

    - by b0x0rz
    what is the best practice? call a function then return if you test for something, or test for something then call? i prefer the test inside of function because it makes an easier viewing of what functions are called. for example: protected void Application_BeginRequest(object sender, EventArgs e) { this.FixURLCosmetics(); } and private void FixURLCosmetics() { HttpContext context = HttpContext.Current; if (!context.Request.HttpMethod.ToString().Equals("GET", StringComparison.OrdinalIgnoreCase)) { // if not a GET method cancel url cosmetics return; }; string url = context.Request.RawUrl.ToString(); bool doRedirect = false; // remove > default.aspx if (url.EndsWith("/default.aspx", StringComparison.OrdinalIgnoreCase)) { url = url.Substring(0, url.Length - 12); doRedirect = true; } // remove > www if (url.Contains("//www")) { url = url.Replace("//www", "//"); doRedirect = true; } // redirect if necessary if (doRedirect) { context.Response.Redirect(url); } } is this good: if (!context.Request.HttpMethod.ToString().Equals("GET", StringComparison.OrdinalIgnoreCase)) { // if not a GET method cancel url cosmetics return; }; or should that test be done in Application_BeginRequest? what is better? thnx

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  • Managed .NET Equivalent to CreateFile & WriteFile from WinBase (kernel32.dll)

    - by StevenH
    I am working with a legacy file format. The file is created using unmanaged C++ that utilizes the WinBase.h CreateFile() & WriteFile() functions (found in the kernel32.dll). I have been using P/Invoke interop to access these native functions like so: [DllImport("kernel32.dll")] public static extern bool WriteFile( IntPtr hFile, byte[] lpBuffer, uint nNumberOfBytesToWrite, out uint lpNumberOfBytesWritten, [In] ref NativeOverlapped lpOverlapped); [DllImport("kernel32.dll", SetLastError = true)] public static extern bool WriteFileEx( IntPtr hFile, byte[] lpBuffer, uint nNumberOfBytesToWrite, [In] ref NativeOverlapped lpOverlapped, WriteFileCompletionDelegate lpCompletionRoutine); [DllImport("kernel32.dll", SetLastError = true)] public static extern IntPtr CreateFile( string lpFileName, uint dwDesiredAccess, uint dwShareMode, IntPtr lpSecurityAttributes, uint dwCreationDisposition, uint dwFlagsAndAttributes, IntPtr hTemplateFile); [DllImport("kernel32.dll", SetLastError = true)] public static extern bool CloseHandle(IntPtr hObject); public delegate void WriteFileCompletionDelegate( UInt32 dwErrorCode, UInt32 dwNumberOfBytesTransfered, ref NativeOverlapped lpOverlapped); The issue with this is when I call WriteFile(), the file is always overwritten by the proceeding call. I need to find a compatible .NET equivalent that would allow me to produce the exact same format of output. Thanks.

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  • JasperReports reports access image via authenticated URL

    - by user363115
    Hi all, I am hoping that this is a simple issue with a simple solution and that I have missed something obvious. Let me explain the problem; We have an application that generates PDF reports (using Jasper). These reports contain data from our database, as well as imagery (photographs). These photographs are stored in S3. We use signed URLs to access these photographs. We link these photographs into our Jasper reports using these S3 URLs. Because the S3 URLs are signed and time-limited (by design), the process is as follows; User requests a report to be generated, Report is filled, and goes to our database (at which time UUIDs to any required images are retrieved), For each UUID an S3 signed URL must be generated, To do this the URL behind each report image is a call to an authenticated URL in our app (/get_img?uuid=foo), The controller behind this URL generates a signed S3 URL and returns it, Reports loads the image. The problem is with step (4) - the call to the authenticated URL fails because Jasper does not pass any authentication information with the request. Is there a solution here? Thanks all for your time. Ben

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  • What do the 'size' numbers mean in the windbg !heap output?

    - by pj4533
    I see output like this in my DMP file: Heap entries for Segment00 in Heap 00150000 00150640: 00640 . 00040 [01] - busy (40) 00150680: 00040 . 01808 [01] - busy (1800) 00151e88: 01808 . 00210 [01] - busy (208) 00152098: 00210 . 00228 [00] 001522c0: 00228 . 00030 [01] - busy (22) 001522f0: 00030 . 00018 [01] - busy (10) 00152308: 00018 . 00048 [01] - busy (3c) The WinDbg docs say this: Heap entries for Segment00 in Heap 250000 0x01 - HEAP_ENTRY_BUSY 0x02 - HEAP_ENTRY_EXTRA_PRESENT 0x04 - HEAP_ENTRY_FILL_PATTERN 0x08 - HEAP_ENTRY_VIRTUAL_ALLOC 0x10 - HEAP_ENTRY_LAST_ENTRY 0x20 - HEAP_ENTRY_SETTABLE_FLAG1 0x40 - HEAP_ENTRY_SETTABLE_FLAG2 Entry Prev Cur 0x80 - HEAP_ENTRY_SETTABLE_FLAG3 Address Size Size flags (Bytes used) (Tag name) 00250000: 00000 . 00b90 [01] - busy (b90) 00250b90: 00b90 . 00038 [01] - busy (38) 00250bc8: 00038 . 00040 [07] - busy (24), tail fill (NTDLL!LDR Database) The spacing is weird in the docs though. Does that mean 'entry address' and 'prev size' and 'cur size', or are the 'entry' 'prev' and 'cur' not for the line below? What does 'prev size' and 'cur size' mean? Especially with regard to 'bytes used'. What is the difference between 'bytes used' and 'cur size'?

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  • Passing NULL value

    - by FFXIII
    Hi. I use an instance of NSXMLParser. I store found chars in NSMutableStrings that are stored in an NSMutableDictionary and these Dicts are then added to an NSMutableArray. When I test this everything seems normal: I count 1 array, x dictionnaries and x strings. In a detailview controller file I want to show my parsed results. I call the class where everthing is stored but I get (null) returned. This is what I do (wrong): XMLParser.h @interface XMLParser : NSObject { NSMutableArray *array; NSMUtableDictionary *dictionary; NSSMutabletring *element; } @property (nonatomic, retain) NSMutableArray *array; @property (nonatomic, retain) NSMutableDictionary *dictionary; @property (nonatomic, retain) NSMutableString *element; XMLParser.m @synthesize array, dictionary, element; //parsing goes on here & works fine //so 'element' is filled with content and stored in a dict in an array //and released at the end of the file In my controller file I do this: controller.h @class XMLParser; @interface controller : UIViewController { XMLParser *aXMLParser; } @property (nonatomic, retain) XMLParser *aXMLParser; controller.m #import "XMLParser.h" @synthesize aXMLParser; - (void)viewDidLoad { NSLog(@"test array: %@", aXMLParser.array); NSLog(@"test dict: %@", aXMLParser.dictionary); NSLog(@"test element: %@", aXMLParser.element); } When I test the value of my array, a dict or an element in the XMLParser.h file I get my result. What am I doing wrong so I can't call my results in my controller file? Any help is welcome, because I'm pretty stuck right now :/

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  • Java: design for using many executors services and only few threads

    - by Guillaume
    I need to run in parallel multiple threads to perform some tests. My 'test engine' will have n tests to perform, each one doing k sub-tests. Each test result is stored for a later usage. So I have n*k processes that can be ran concurrently. I'm trying to figure how to use the java concurrent tools efficiently. Right now I have an executor service at test level and n executor service at sub test level. I create my list of Callables for the test level. Each test callable will then create another list of callables for the subtest level. When invoked a test callable will subsequently invoke all subtest callables test 1 subtest a1 subtest ...1 subtest k1 test n subtest a2 subtest ...2 subtest k2 call sequence: test manager create test 1 callable test1 callable create subtest a1 to k1 testn callable create subtest an to kn test manager invoke all test callables test1 callable invoke all subtest a1 to k1 testn callable invoke all subtest an to kn This is working fine, but I have a lot of new treads that are created. I can not share executor service since I need to call 'shutdown' on the executors. My idea to fix this problem is to provide the same fixed size thread pool to each executor service. Do you think it is a good design ? Do I miss something more appropriate/simple for doing this ?

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  • Applying correct bindings to WPF datatemplate to maximize reusability

    - by johncatfish
    Hi. I have a WPF application. I want to apply that datatemplate to a Listbox filled with records from Table02. Then, for each listboxitem I need to bind the combobox to the same database table (Table01), but for each listboxitem the selected item will vary. It will be a foreign key to Table01. <DataTemplate x:Key="Table01DataTemplate"> <Grid> <ComboBox ItemsSource="{Binding Model.IQueryable_Table01, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}" SelectedValue="{Binding Table01_ForeignKey}" DisplayMemberPath="name" SelectedValuePath="id" /> <!-- Other stuff --> </Grid> </DataTemplate> <ListBox x:Name="lbTest" ItemTemplate="{StaticResource Table01DataTemplate}" /> <!-- In .cs file lbTest.DataContext = this; --> Notes: Model.IQueryable_Table01 is a property which encapsulates a Linq-to-sql call returning a IQueryable. lbTest will be filled by setting ItemsSource with a Linq-to-sql call. Is this a good way to do the bindings in a data template for a maximum reusability? I also thought of replacing AncestorType={x:Type Window} with lbTest.DataContext = this; AncestorType={x:Type Application} and lbTest.DataContext = App.Current; But it didn't work (Exception on loading) and I don't know if there's any caveats or down-sides to this approach. Is this good? Any suggestions or improvements? Thanks.

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  • new image makes http request even though cached?

    - by joshs
    I have a javascript slide show that creates the next slide dynamically and then moves it into view. Since the images are actually sprites, the src is transparent.png and the actual image is mapped via background:url(.. in css. Everytime (well, most of the time) the script creates a new Element, Firefox makes an http request for transparent.png. I have a far-future expires header, and Firefox is respecting all other files' expiries. Is there a way to avoid these unnecessary requests. Even though the server is returning 304 unmodified responses, it would be nice if Firefox would respect the expiries on dynamically created images. I suspect that if I injected a simple string instead of using new Element, this might solve the problem, but I use some methods on Prototypes extended Element object, so I would like to avoid a bunch of html strings in my js file. This is a nit-picky question, but I'm working on front-end optimization now, so I thought I would address it. Thanks.

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  • How to read a parameter passed to a facelet from a backing bean

    - by Antonio
    Hi, I've written a facelet, and a corresponding backing bean, that implements user management (addition, deletion and so on). I'd want to be able to perform some custom processing when, for instance, a new user is added. There is a "create" button in the facelet, whose click event is handled by its backing bean. At the end of the event handler, I'd want to be able to call a method of another backing bean, which is not known because ideally the facelet can be used in several pages, with different custom processing. I thought to implement this feature by providing to the facelet a backing bean name and a method name, like this: <myfacelet:subaccounts backingBean="myBackingBean" createListener="createListener" /> and at the end of the event handler call #{myBackingBean.createListener} someway. I'm using this method (along with some overloads) to obtain a MethodExpression: protected MethodExpression getMethodExpression(String beanName, String methodName, Class<?> expectedReturnType, Class<?>[] expectedParamTypes) { ExpressionFactory expressionFactory; MethodExpression method; ELContext elContext; String el; el = String.format("#{%s['%s']}", beanName, methodName); expressionFactory = getApplication().getExpressionFactory(); elContext = getFacesContext().getELContext(); method = expressionFactory.createMethodExpression(elContext, el, expectedReturnType, expectedParamTypes); return method; } and the click event handler should look like: public void saveSubaccountListener(ActionEvent event) { MethodExpression method; ... method = getMethodExpression( "backingBean", "createSubaccountListener", SubuserBean.class); if (method != null) method.invoke( getFacesContext().getELContext(), new Object[] { _editedSubuser }); } That works fine as long as I provide an existing bean name (myBackingBean), but if I use backingBean the invoke() doesn't work due to the following error: javax.el.PropertyNotFoundException: Target Unreachable, identifier 'backingBean' resolved to null Is there a way I can retrieve from the facelet backing bean the value of a parameter that has been passed to the facelet? In my case, the value of backingBean, which should be myBackingBean? I've searched for and tried different solutions, but with no luck yet.

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  • How to read the birthday_date from the Facebook API

    - by Steve
    I have been chasing my tail on this! And it should be so simple!! I have an app in FaceBook that is working fine. However, I need to get the user's birth date. I have successfully got the request for extended permissions, but cannot get the birthday_date out and into a variable/store in database. <?php require_once('facebook.php'); $facebook = new Facebook(array( 'appId' => 'xxxxx', 'secret' => 'yyyyyyy', 'cookie' => true )); if ($facebook->getSession()) { $uid = $facebook->getUser(); $fbme = $facebook->api('/me'); } else { $params = array( 'fbconnect'=>0, 'canvas'=>1, 'req_perms'=>'publish_stream','email','user_location','user_birthday' ); $loginUrl = $facebook->getLoginUrl($params); print "<script type='text/javascript'>top.location.href = '$loginUrl';</script>"; } $session = $facebook->getSession(); $token = $session['access_token']; I would be very grateful if someone could show me the PHP code that reads the extended permissions and places the results into variables. Thanks Steve

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  • What could cause xmlrpclib.ResponseError: ResponseError() ?

    - by Tom
    Hi, I am experimenting with XML-RPC. I have the following server script (python): from SimpleXMLRPCServer import SimpleXMLRPCServer server = SimpleXMLRPCServer(('localhost', 9000)) def return_input(someinput): return someinput server.register_function(return_input) try: print 'ctrl-c to stop server' server.serve_forever() except KeyboardInterrupt: print 'stopping' and the following client script: import xmlrpclib server = xmlrpclib.ServerProxy('http://www.example.com/pathto/xmlrpcTester2.py') print server.return_input('some input') I have tested this locally and it works fine. All it does it spit out the input fron the client script, which is right. However, when I try to do it on a remote server I get the following error: Traceback (most recent call last): File "client.py", line 4, in <module> print server.return_input('some input') File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/xmlrpclib.py", line 1199, in __call__ return self.__send(self.__name, args) File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/xmlrpclib.py", line 1489, in __request verbose=self.__verbose File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/xmlrpclib.py", line 1253, in request return self._parse_response(h.getfile(), sock) File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/xmlrpclib.py", line 1392, in _parse_response return u.close() File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/xmlrpclib.py", line 836, in close raise ResponseError() xmlrpclib.ResponseError: ResponseError() Any ideas what could cause this? Thanks in advance for your help.

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  • PHP: how to access variables inside a function that have been declared outside of it?

    - by Chris
    Please, I am very new and have not been confronted with OOP and all this related stuff, which I guess may be related to this issue (public, private, ...). So, any help and suggestions are very appreciated! :) At the very beginning of each page I include a file that starts the SESSION etc, lets call it session.php. In this file session.php, I include a file that contains a function, let's call it function1.php, because I need the function to be available in session.php. However, later in the main page I also include function2.php which needs to access variables set in session.php, so I additionally tried to include session.php in function2.php. The problem is that an error occurs as function1 will be declared multiple times... Fatal error: Cannot redeclare function1() (previously declared in ... So, what would be a more elegant and clean(er) solution for this? How could you solve it? Basically, I'd need to access variables inside a function that have been included in the main page before... Thank you very much in advance!

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  • Why can't I extract a C++ type from a Python type using boost::python::extractor?

    - by Robin
    I've wrapped a C++ class using Py++ and everything is working great in Python. I can instantiate the c++ class, call methods, etc. I'm now trying to embed some Python into a C++ application. This is also working fine for the most-part. I can call functions on a Python module, get return values, etc. The python code I'm calling returns one of the classes that I wrapped: import _myextension as myext def run_script(arg): my_cpp_class = myext.MyClass() return my_cpp_class I'm calling this function from C++ like this: // ... excluding error checking, ref counting, etc. for brevity ... PyObject *pModule, *pFunc, *pArgs, *pReturnValue; Py_Initialize(); pModule = PyImport_Import(PyString_FromString("cpp_interface")); pFunc = PyObject_GetAttrString(pModule, "run_script"); pArgs = PyTuple_New(1); PyTuple_SetItem(pArgs, 0, PyString_FromString("an arg")); pReturnValue = PyObject_CallObject(pFunc, pArgs); bp::extract< MyClass& > extractor(pReturnValue); // PROBLEM IS HERE if (extractor.check()) { // This check is always false MyClass& cls = extractor(); } The problem is the extractor never actually extracts/converts the PyObject* to MyClass (i.e. extractor.check() is always false). According to the docs this is the correct way to extract a wrapped C++ class. I've tried returning basic data types (ints/floats/dicts) from the Python function and all of them are extracted properly. Is there something I'm missing? Is there another way to get the data and cast to MyClass?

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  • How might one cope with the ambiguous value produced by GetDllDirectory?

    - by Integer Poet
    GetDllDirectory produces an ambiguous value. When the string this call produces is empty, it means one of the following: nobody has called SetDllDirectory somebody passed NULL to SetDllDirectory somebody passed an empty string to SetDllDirectory The first two cases are equivalent for my purposes, but the third case is a problem. If I want to write save/restore code (call GetDllDirectory to save the "old" value, SetDllDirectory to set a "new" value temporarily, and later SetDllDirectory again to restore the "old" value), I run the risk of reversing some other programmer's intent. If the other programmer intended for the current working directory to be in the DLL search order (in other words, one of the first two bullets is true), and I pass an empty string to SetDllDirectory, I will be taking the current working directory out of the DLL search order, reversing the other programmer's intent. Can anyone suggest an approach to eliminate or work around this ambiguity? P.S. I know having the current working directory in the DLL search order could be interpreted as a security hole. Nevertheless, it is the default behavior, and my code is not in a position to undo that; my code needs to be compatible with the expectations of all potential callers, many of which are large and old and beyond my control.

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  • SQL Query - 20mil records - Best practice to return information

    - by eqiz
    I have a SQL database that has the following table: Table: PhoneRecords ID(identity Seed) FirstName LastName PhoneNumber ZipCode Very simple straight forward table. This table has over 20million records. I am looking for the best way to do queries that pull out records based off area codes from the table. For instance here is an example query that I have done. SELECT phonenumber, firstname FROM [PhoneRecords] WHERE (phone LIKE '2012042%') OR (phone LIKE '2012046%') OR (phone LIKE '2012047%') OR (phone LIKE '2012083%') OR (phone LIKE '2012088%') OR (phone LIKE '2012841%') As you can see this is an ugly query, but it would get the job done (if I wasn't running into timeout issues) Can anyone tell me the best way for speed/optimization to do the above query to display the results? Currently that query above takes around 2 hours to complete on a 9gb 1600mhz ram, i7 930 quadcore OC'd 4.01ghz. I obviously have the computer power required to do such a query, but still takes too long for queries.

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  • Problems with Backbone.Model callback and THIS

    - by Rev. Samuel
    I'm building a simple weather widget. The current weather conditions are read out of the National Weather Service xml file and then I want to parse and store the relevant data in the model but the callback for the $.ajax won't connect (the way I'm doing it). var Weather = Backbone.Model.extend({ initialize: function(){ _.bindAll( this, 'update', 'startLoop', 'stopLoop' ); this.startLoop(); }, startLoop: function(){ this.update(); this.interval = window.setInterval( _.bind( this.update, this ), 1000 * 60 * 60 ); }, stopLoop: function(){ this.interval = window.clearInterval( this.interval ); }, store: function( data ){ this.set({ icon : $( data ).find( 'icon_url_name' ).text() }); }, update: function(){ $.ajax({ type: 'GET', url: 'xml/KROC.xml', datatype: 'xml' }) .done( function( data ) { var that = this; that.store( $( data ).find( 'current_observation' )[ 0 ] ); }); } }); var weather = new Weather(); The data is read correctly but I can't get the done function of the call back to call the store function. (I would be happy if the "done" would just parse and then do "this.set". Thanks in advance for your help.

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  • C: Pointers to any type?

    - by dragme
    I hear that C isn't so type-safe and I think that I could use that as an advantage for my current project. I'm designing an interpreter with the goal for the VM to be extremely fast, much faster than Ruby and Python, for example. Now I know that premature optimization "is the root of all evil" but this is rather a conceptual problem. I have to use some sort of struct to represent all values in my language (from number over string to list and map) Would the following be possible? struct Value { ValueType type; void* value; } I would store the actual values elsewhere, e.g: a separate array for strings and integers, value* would then point to some member in this table. I would always know the type of the value via the type variable, so there wouldn't be any problems with type errors. Now: Is this even possible in terms of syntax and typing?

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  • Subversion commands not being run by Ubuntu rc.local

    - by talentedmrjones
    Here is my rc.local for an autoscaling amazon ec2 instance based on ubuntu: (Note that user names, domains, and paths have been changed for security purposes) logger "Begin rc.local startup script:" logger "svn checkout" sudo -u nonRootUser /usr/bin/svn co svn+ssh://[email protected]/path/to/repo /var/www/html | logger logger "chown writeable folder" chown www-data /var/www/html/writeableFolder logger "restart apache" /etc/init.d/apache2 restart | logger exit 0 And here is the output of sudo tail -n 40 /var/log/syslog Mar 10 22:05:20 ubuntu logger: Begin rc.local startup script: Mar 10 22:05:20 ubuntu logger: svn checkout Mar 10 22:05:20 ubuntu logger: chown writeable folder Of course its not getting to apache2 restart because it error'd on the chown. I did find however that if I do a checkout beforehand, and set the rc.local svn command to an svn update, that it still does not run the svn command but does output apache2 restart successfully. These same svn commands work perfectly when I run them manually, tho it's strange that within rc.local they do not produce any output whatsoever to logger yet apache2 restart does. I've also tried running the svn co and svn update both with sudo -u and without. How do I get the svn command to run? Either a full checkout or an update. At this point either would be better than nothing!

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  • Use properties or methods to expose business rules in C#?

    - by Val
    I'm writing a class to encapsulate some business rules, each of which is represented by a boolean value. The class will be used in processing an InfoPath form, so the rules get the current program state by looking up values in a global XML data structure using XPath operations. What's the best (most idiomatic) way to expose these rules to callers -- properties or public methods? Call using properties Rules rules = new Rules(); if ( rules.ProjectRequiresApproval ) { // get approval } else { // skip approval } Call using methods Rules rules = new Rules(); if ( rules.ProjectRequiresApproval() ) { // get approval } else { // skip approval } Rules class exposing rules as properties public class Rules() { private int _amount; private int threshold = 100; public Rules() { _amount = someExpensiveXpathOperation; } // rule property public bool ProjectRequiresApproval { get { return _amount < threshold } } } Rules class exposing rules as methods public class Rules() { private int _amount; private int threshold = 100; public Rules() { _amount = someExpensiveXpathOperation; } // rule method public bool ProjectRequiresApproval() { return _amount < threshold; } } What are the pros and cons of one over the other?

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  • iPhone and iPad : Doing a "select * from something" query in a SQLite database

    - by Abramodj
    Hi folks, i'm trying to use the SQLite data base in my iPad app, and here's my function to make a query: - (void)executeQuery:(char*)query { NSString *file = [self getWritableDBPath]; NSFileManager *fileManager = [NSFileManager defaultManager]; BOOL success = [fileManager fileExistsAtPath:file]; // If its not a local copy set it to the bundle copy if(!success) { //file = [[NSBundle mainBundle] pathForResource:DATABASE_TITLE ofType:@"db"]; [self createEditableCopyOfDatabaseIfNeeded]; } dataArray = NULL; dataArray = [NSMutableArray array]; sqlite3 *database = NULL; if (sqlite3_open([file UTF8String], &database) == SQLITE_OK) { sqlite3_exec(database, query, loadTimesCallback, dataArray, NULL); } sqlite3_close(database); [self logResults]; } if I call [self executeQuery:"select name from table1"]; everything is working fine. But if i call [self executeQuery:"select * from cars"]; the app crashes telling me that the NSMutableArray dataArray is not the right kind of variable where to set the query results. So, how can i do a "select * form table1" query, and store the results? Thanks! EDIT: Here's my loadTimesCallback method: static int loadTimesCallback(void *context, int count, char **values, char **columns) { NSMutableArray *times = (NSMutableArray *)context; for (int i=0; i < count; i++) { const char *nameCString = values[i]; [times addObject:[NSString stringWithUTF8String:nameCString]]; } return SQLITE_OK; }

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  • In .NET which loop runs faster for or foreach

    - by Binoj Antony
    In c#/VB.NET/.NET which loop runs faster for or foreach? Ever since I read that for loop works faster than foreach a long time ago I assumed it stood true for all collections, generic collection all arrays etc. I scoured google and found few articles but most of them are inconclusive (read comments on the articles) and open ended. What would be ideal is to have each scenarios listed and the best solution for the same e.g: (just example of how it should be) for iterating an array of 1000+ strings - for is better than foreach for iterating over IList (non generic) strings - foreach is better than for Few references found on the web for the same: Original grand old article by Emmanuel Schanzer CodeProject FOREACH Vs. FOR Blog - To foreach or not to foreach that is the question asp.net forum - NET 1.1 C# for vs foreach [Edit] Apart from the readability aspect of it I am really interested in facts and figures, there are applications where the last mile of performance optimization squeezed do matter.

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  • [C#] Two System.Drawing methods manifest slow drawing or flickery: Solutions? or Other Options?

    - by Luke Mcneice
    Hi all, I am doing a little graphing via the System.Drawing and im having a few problems. I'm holding data in a Queue and i'm drawing(graphing) out that data onto three picture boxes this method fills the picture box then scrolls the graph across. so not to draw on top of the previous drawings (and graduly looking messier) i found 2 solutions to draw the graph. Call plot.Clear(BACKGOUNDCOLOR) before the draw loop [block commented] although this causes a flicker to appear from the time it takes to do the actual drawing loop. call plot.DrawLine(channelPen[5], j, 140, j, 0); just before each drawline [commented] although this causes the drawing to start ok then slow down very quickly to a crawl as if a wait command had been placed before the draw command. Here is the Code for reference: /*plotx.Clear(BACKGOUNDCOLOR) ploty.Clear(BACKGOUNDCOLOR) plotz.Clear(BACKGOUNDCOLOR)*/ for (int j = 1; j < 599; j++) { if (j > RealTimeBuffer.Count - 1) break; QueueEntity past = RealTimeBuffer.ElementAt(j - 1); QueueEntity current = RealTimeBuffer.ElementAt(j); if (j == 1) { //plotx.DrawLine(channelPen[5], 0, 140, 0, 0); //ploty.DrawLine(channelPen[5], 0, 140, 0, 0); //plotz.DrawLine(channelPen[5], 0, 140, 0, 0); } //plotx.DrawLine(channelPen[5], j, 140, j, 0); plotx.DrawLine(channelPen[0], j - 1, (((past.accdata.X - 0x7FFF) / 256) + 64), j, (((current.accdata.X - 0x7FFF) / 256) + 64)); //ploty.DrawLine(channelPen[5], j, 140, j, 0); ploty.DrawLine(channelPen[1], j - 1, (((past.accdata.Y - 0x7FFF) / 256) + 64), j, (((current.accdata.Y - 0x7FFF) / 256) + 64)); //plotz.DrawLine(markerPen, j, 140, j, 0); plotz.DrawLine(channelPen[2], j - 1, (((past.accdata.Z - 0x7FFF) / 256) + 94), j, (((current.accdata.Z - 0x7FFF) / 256) + 94)); } Is there any tricks to avoid these overheads? If not would there be any other/better solutions?

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  • Is it possible to give a python dict an initial capacity (and is it usefull)

    - by Peter Smit
    I am filling a python dict with around 10,000,000 items. My understanding of dict (or hashtables) is that when too much elements get in them, the need to resize, an operation that cost quite some time. Is there a way to say to a python dict that you will be storing at least n items in it, so that it can allocate memory from the start? Or will this optimization not do any good to my running speed? (And no, I have not checked that the slowness of my small script is because of this, I actually wouldn't now how to do that. This is however something I would do in Java, set the initial capacity of the HashSet right)

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  • Getting an non-object error in my php script

    - by Disowned
    Hey I was trying to call a script to made some changes to an html file, however when I run the script it tells me that it's making a call to a non-object. Obviously I did something wrong, but what? Here's the script. /*Dom controllers*/ $dom = new DOMDocument(); $dom->loadHTML('index.html'); $id = $dom->getElementById('contact_us'); $p = $dom->appendChild(new DOMElement('p')); $op = $dom->getElementsByTagName('p'); /* Dem POST vars used by dat Ajax mah ziggen, yeah boi*/ if (isset($_POST['Home']) && isset($_POST['About']) && isset($_POST['Contact']) && isset($_POST['sexyText'])){ $home = $_POST['Home']; $about = $_POST['About']; $contact = $_POST['Contact']; $text = $_POST['sexyText']; trim($home); trim($about); trim($contact); trim($text); } function post(){ global $dom, $id, $home, $about, $contact, $text, $textp, $p, $op; $textp = $dom->createTextNode($text); $p->appendChild($textp); $id->replaceChild($p, $op); $dom->saveHTMLFile('index.html'); } post(); echo 1; ?> The error happens at the replaceChild function.

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