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  • Why doesn't String's hashCode() cache 0?

    - by polygenelubricants
    I noticed in the Java 6 source code for String that hashCode only caches values other than 0. The difference in performance is exhibited by the following snippet: public class Main{ static void test(String s) { long start = System.currentTimeMillis(); for (int i = 0; i < 10000000; i++) { s.hashCode(); } System.out.format("Took %d ms.%n", System.currentTimeMillis() - start); } public static void main(String[] args) { String z = "Allocator redistricts; strict allocator redistricts strictly."; test(z); test(z.toUpperCase()); } } Running this in ideone.com gives the following output: Took 1470 ms. Took 58 ms. So my questions are: Why doesn't String's hashCode() cache 0? What is the probability that a Java string hashes to 0? What's the best way to avoid the performance penalty of recomputing the hash value every time for strings that hash to 0? Is this the best-practice way of caching values? (i.e. cache all except one?) For your amusement, each line here is a string that hash to 0: pollinating sandboxes amusement & hemophilias schoolworks = perversive electrolysissweeteners.net constitutionalunstableness.net grinnerslaphappier.org BLEACHINGFEMININELY.NET WWW.BUMRACEGOERS.ORG WWW.RACCOONPRUDENTIALS.NET Microcomputers: the unredeemed lollipop... Incentively, my dear, I don't tessellate a derangement. A person who never yodelled an apology, never preened vocalizing transsexuals.

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  • SQL server 2005 query not running

    - by Aayushi
    Hi, Before posting this question, I have tried so many things but that was not helpful for me. I want to rename the column of table at sql server 2005, following query I have run at sql server2005: 1) ALTER TABLE Details RENAME COLUMN AccountID TO UID; but it gives me the error: Incorrect syntax near the keyword 'COLUMN'. 2)I have added one new column in the table by query: ALTER TABLE Details ADD BID uniqueidentifier; and then I want to set the coulmn property to not null . How can i do that? Thanks in advance AS

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  • Link failure with either abnormal memory consumption or LNK1106 in Visual Studio 2005.

    - by Corvin
    Hello, I am trying to build a solution for windows XP in Visual Studio 2005. This solution contains 81 projects (static libs, exe's, dlls) and is being successfully used by our partners. I copied the solution bundle from their repository and tried setting it up on 3 similar machines of people in our group. I was successful on two machines and the solution failed to build on my machine. The build on my machine encountered two problems: During a simple build creation of the biggest static library (about 522Mb in debug mode) would fail with the message "13libd\ui1d.lib : fatal error LNK1106: invalid file or disk full: cannot seek to 0x20101879" Full solution rebuild creates this library, however when it comes to linking the library to main .exe file, devenv.exe spawns link.exe which consumes about 80Mb of physical memory and 250MB of virtual and spawns another link.exe, which does the same. This goes on until the system runs out of memory. On PCs of my colleagues where successful build could be performed, there is only one link.exe process which uses all the memory required for linking (about 500Mb physical). There is a plenty of hard drive space on my machine and the file system is NTFS. All three of our systems are similar - Core2Quad processors, 4Gb of RAM, Windows XP SP3. We are using Visual studio installed from the same source. I tried using a different RAM and CPU, using dedicated graphics adapter to eliminate possibility of video memory sharing influencing the build, putting solution files to different location, using different versions of VS 2005 (Professional, Standard and Team Suite), changing the amount of available virtual memory, running memtest86 and building the project from scratch (i.e. a clean bundle). I have read what MSDN says about LNK1106, none of the cases apply to me except for maybe "out of heap space", however I am not sure how I should fight this. The only idea that I have left is reinstalling the OS, however I am not sure that it would help and I am not sure that my situation wouldn't repeat itself on a different machine. Would anyone have any sort of advice for me? Thanks

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  • Global name not defined error in Django/Python trying to set foreignkey

    - by Mark
    Summary: I define a method createPage within a file called PageTree.py that takes a Source model object and a string. The method tries to generate a Page model object. It tries to set the Page model object's foreignkey to refer to the Source model object which was passed in. This throws a NameError exception! I'm trying to represent a website which is structured like a tree. I define the Django models Page and Source, Page representing a node on the tree and Source representing the contents of the page. (You can probably skip over these, this is a basic tree implementation using doubly linked nodes). class Page(models.Model): name = models.CharField(max_length=50) parent = models.ForeignKey("self", related_name="children", null=True); firstChild = models.ForeignKey("self", related_name="origin", null=True); nextSibling = models.ForeignKey("self", related_name="prevSibling", null=True); previousSibling = models.ForeignKey("self", related_name="nxtSibling", null=True); source = models.ForeignKey("Source"); class Source(models.Model): #A source that is non dynamic will be refered to as a static source #Dynamic sources contain locations that are names of functions #Static sources contain locations that are places on disk name = models.CharField(primary_key=True, max_length=50) isDynamic = models.BooleanField() location = models.CharField(max_length=100); I've coded a python program called PageTree.py which allows me to request nodes from the database and manipulate the structure of the tree. Here is the trouble making method: def createPage(pageSource, pageName): page = Page() page.source = pageSource page.name = pageName page.save() return page I'm running this program in a shell through manage.py in Windows 7 manage.py shell from mysite.PageManager.models import Page, Source from mysite.PageManager.PageTree import * ... create someSource = Source(), populate the fields, and save it ... createPage(someSource, "test") ... NameError: global name 'source' is not defined When I type in the function definition for createPage into the shell by hand, the call works without error. This is driving me bonkers and help is appreciated.

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  • Int - number too large. How to get program to fail?

    - by Dave
    Hi Problem: How do you get a program to fail if a number goes beyond the bounds of its type? This code below gives the wrong answer for sum of primes under 2 million as I'd used an int instead of a long. [TestMethod] public void CalculateTheSumOfPrimesBelow2million() { int result = PrimeTester.calculateTheSumOfPrimesBelow(2000000); // 2million Assert.AreEqual(1, result); // 1,179,908,154 .. this was what I got with an int... // correct answer was 142,913,828,922 with a long } public static class PrimeTester { public static int calculateTheSumOfPrimesBelow(int maxPrimeBelow) { // we know 2 is a prime number int sumOfPrimes = 2; int currentNumberBeingTested = 3; while (currentNumberBeingTested < maxPrimeBelow) { double squareRootOfNumberBeingTested = (double)Math.Sqrt(currentNumberBeingTested); bool isPrime = true; for (int i = 2; i <= squareRootOfNumberBeingTested; i++) { if (currentNumberBeingTested % i == 0) { isPrime = false; break; } } if (isPrime) sumOfPrimes += currentNumberBeingTested; currentNumberBeingTested += 2; // as we don't want to test even numbers } return sumOfPrimes; } }

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  • Measuring the CPU frequency scaling effect

    - by Bryan Fok
    Recently I am trying to measure the effect of the cpu scaling. Is it accurate if I use this clock to measure it? template<std::intmax_t clock_freq> struct rdtsc_clock { typedef unsigned long long rep; typedef std::ratio<1, clock_freq> period; typedef std::chrono::duration<rep, period> duration; typedef std::chrono::time_point<rdtsc_clock> time_point; static const bool is_steady = true; static time_point now() noexcept { unsigned lo, hi; asm volatile("rdtsc" : "=a" (lo), "=d" (hi)); return time_point(duration(static_cast<rep>(hi) << 32 | lo)); } }; Update: According to the comment from my another post, I believe redtsc cannot use for measure the effect of cpu frequency scaling because the counter from the redtsc does not affected by the CPU frequency, am i right?

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  • Free PHP framework/library for single-sign on / cross domain login

    - by Dennis Cheung
    I am looking for free (non GPL is better) SSO framework/library implementation or code samples. There are many kind of SSO implementation. Sharing cookie, sharing session, one time token, associative accounts, etc, etc. (BTW, any good article compare them?) Is there any keyword I should google and reuse before before I start to implement our own wheel. I know OpenID, but which is too much and it is not our need. We rather keep it KISS. We just want share the credentials of user that could save users from another login form.

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  • Purpose of singletons in programming

    - by thecoshman
    This is admittedly a rather loose question. My current understanding of singletons is that they are a class that you set up in such a way that only one instance is ever created. This sounds a lot like a static class to me. The main differnce being that with a static class you don't / can't instance it, you just use it such as Math.pi(). With a singletong class, you would still need to do something like singleton mySingleton = new singleton(); mysingleton.set_name("foo"); singleton otherSingleton = new singleton(); // correct me if i am wrong, but mysingleton == othersingleton right now, yes? // this the following should happen? otherSingleston.set_name("bar"); mysingleton.report_name(); // will output "bar" won't it? Please note, I am asking this language independently, more about the concept. So I am not so worried about actually how to coed such a class, but more why you would wan't to and what thing you would need to consider.

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  • Replacing keywords in text with php & mysql

    - by intacto
    Hello, I have a news site containing an archive with more than 1 million news. I created a word definitions database with about 3000 entries, consisting of word-definition pairs. What I want to do is adding a definition next to every occurence of these words in the news. I cant make a static change as I can add a new keyword everyday, so i can make it realtime or cached. The question is, a str_replace or a preg_replace would be very slow for searching 3 thousand keywords in a text and replacing them. Are there any fast alternatives?

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  • Listing C/C++ functions (Code analysis in Unix)

    - by Jond
    Whether we're maintaining unfamiliar code or checking out the implementation details of an Apache module it can help if we can quickly traverse the code and build up an overview of what we're looking at. Grep serves most of my daily needs but there are some cases where it just wont do. Here's a common example of how it can help. To find the definition of a PHP function I'm interested in I can type this at the command line: grep -r "function myfunc" . This could be adapted very quickly to C or C++ if we know the return type, but things become more complicated if, say, I want to list every method that my class provides: grep "function " ./src/mine.class.php Since there's no single keyword that denotes a function or method in C++ and because it's generally more complex syntax, I think I'd need some kind of static code analysis tool, smart use of the C Preprocessor or blind faith the coder followed strict code guidelines (# of whitespace, position of curlies etc) to get these sorts of results. What would you recommend? p.s. be nice, this is my first post ;-) :p

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  • Enum.TryParse with Flags attribute

    - by Sunny
    I have written code to TryParse enum either by value or by its name as shown below. How can I extend this code to include parsing enums with Flags attribute? public static bool TryParse<T>(this T enum_type, object value, out T result) where T : struct { return enum_type.TryParse<T>(value, true, out result); } public static bool TryParse<T>(this T enum_type, object value, bool ignoreCase, out T result) where T : struct { result = default(T); var is_converted = false; var is_valid_value_for_conversion = new Func<T, object, bool, bool>[]{ (e, v, i) => e.GetType().IsEnum, (e, v, i) => value != null, (e, v, i) => Enum.GetNames(e.GetType()).Any(n => String.Compare(n, v.ToString(), i) == 0) || Enum.IsDefined(e.GetType(), v) }; if(is_valid_value_for_conversion.All(rule => rule(enum_type, value, ignoreCase))){ result = (T)Enum.Parse(typeof(T), value.ToString(), ignoreCase); is_converted = true; } return is_converted; } Currently this code works for the following enums: enum SomeEnum{ A, B, C } // can parse either by 'A' or 'a' enum SomeEnum1 : int { A = 1, B = 2, C = 3 } // can parse either by 'A' or 'a' or 1 or "1" Does not work for: [Flags] enum SomeEnum2 { A = 1, B = 2, C = 4 } // can parse either by 'A' or 'a' // cannot parse for A|B Thanks!

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  • Singleton issue causing a buffer overrun

    - by Rudiger
    Hi everyone, Ive created a singleton to store 2 arrays: @interface Globals : NSObject { NSMutableArray *items; NSMutableArray *extras; } + (Globals *)sharedInstance; @property (nonatomic, assign) NSMutableArray *items; @property (nonatomic, assign) NSMutableArray *extras; @end @implementation Globals @synthesize items, extras; + (Globals *)sharedInstance { static Globals *myInstance = nil; @synchronized(self) { if(!myInstance) { myInstance = [[Globals alloc] init]; } } return myInstance; } -(void)dealloc { [items release]; [extras release]; [super dealloc]; } @end When I set the Arrays in the singleton from the App delegate and then output them to NSLog it displays what is expected. But when I call it from a view controller further into the App it displays the first entry fine, some of the second entry and then garbage which is i assume a buffer overrun, sometimes it also crashes. I set the singleton array in the appDelegate like so: Globals *sharedInstance = [Globals sharedInstance]; [sharedInstance setItems:items]; and retrieve it: [[[sharedInstance items] objectAtIndex:indexPath.row] objectForKey:@"name"]; cell.description.text = [[[sharedInstance items] objectAtIndex:indexPath.row] objectForKey:@"description"]; Name works fine in both cells if there is 2, description works in the first case, never in the second case. Is it because the arrays in my singleton aren't static? If so why is it outputting the first entry fine? Cheers for any help.

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  • SimpleTest assertTags - loose matching? (for CakePHP)

    - by Arkaaito
    I'd like to use SimpleTest to set up some functionality tests for our project - in particular, we have a very busy page which has some random components and some static components, and I'd like to be able to write a simple test which only confirms the static bits (preferably only the one or two most important ones). In other words, I want to be able to leave out any tags on the page I don't care about, and write something like: $result = "<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head><title>...</title><meta .../></head><body><script type="text/javascript">...</script><div class="center-splash"><span>Welcome JohnDoe</span><p>Your progress:</p>...</div><div class="left-column">...</div><div class="right-column">...</div>...</body></html>"; $expects = array('html'=>true,'body'=>true,'div'=>array('class'=>'center_splash'),'span'=>true,'Welcome JohnDoe','/span','/div','/body','/html'); $this->assertTagsButIgnoreExtras($result, $expects); When I try this with assertTags it fails. Is there a version of assertTags which allows this - something either officially part of the SimpleTest or CakePHP project or unofficially put out under the MIT license or similar?

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  • Managed WMI Event class is not an event class???

    - by galets
    I am using directions from here: http://msdn.microsoft.com/en-us/library/ms257351(VS.80).aspx to create a managed event class. Here's the code that I wrote: [ManagementEntity] [InstrumentationClass(InstrumentationType.Event)] public class MyEvent { [ManagementKey] public string ID { get; set; } [ManagementEnumerator] static public IEnumerable<MyEvent> EnumerateInstances() { var e = new MyEvent() { ID = "9A3C1B7E-8F3E-4C54-8030-B0169DE922C6" }; return new MyEvent[] { e }; } } class Program { static void Main(string[] args) { var thisAssembly = typeof(Program).Assembly; var wmi_installer = new AssemblyInstaller(thisAssembly, null); wmi_installer.Install(null); wmi_installer.Commit(null); InstrumentationManager.RegisterAssembly(thisAssembly); Console.Write("Press Enter..."); Console.ReadLine(); var e = new MyEvent() { ID = "A6144A9E-0667-415B-9903-220652AB7334" }; Instrumentation.Fire(e); Console.Write("Press Enter..."); Console.ReadLine(); wmi_installer.Uninstall(null); } } I can run a program, and it properly installs. Using wbemtest.exe I can browse to the event, and "show mof": [dynamic: ToInstance, provider("WmiTest, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null")] class MyEvent { [read, key] string ID; }; Notice, the class does not inherit from __ExtrinsicEvent, which is weird... I can also run select * from MyEvent, and get the result. Instrumentation.Fire() also returns no error. However, when I'm trying to subscribe to event using "Notification Query" option, I'm getting 0x80041059 Number: 0x80041059 Facility: WMI Description: Class is not an event class. What am I doing wrong, and is there a correct way to create managed WMI event?

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  • GQL Query with __key__ in List of KEYs

    - by bossylobster
    In the GQL reference [1], it is encouraged to use the IN keyword with a list of values, and to construct a Key from hand the GQL query SELECT * FROM MyModel WHERE __key__ = KEY('MyModel', 'my_model_key') will succeed. However, using the code you would expect to work: SELECT * FROM MyModel WHERE __key__ IN (KEY('MyModel', 'my_model_key1'), KEY('MyModel', 'my_model_key2')) in the Datastore Viewer, there is a complaint of "Invalid GQL query string." What is the correct way to format such a query? [1] http://code.google.com/appengine/docs/python/datastore/gqlreference.html PS I know there are more efficient ways to do this in Python (without constructing a GQL query) and using the remote_api, but each call to the remote_api counts against quota. In an environment where quota is not (necessarily) free, quick and dirty queries are very helpful.

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  • Trying to create fields based on a case statement

    - by dido
    I'm having some trouble with the query below. I am trying to determine if the "category" field is A, B or C and then creating a field based on the category. That field would sum up payments field. But I'm running into error saying "incorrect syntax near keyword As". I am creating this in a SQL View. Using SQL Server 2008 SELECT r.id, r.category CASE WHEN r.category = 'A' then SUM(r.payment) As A_payments WHEN r.category = 'B' then SUM(r.payment) As B_payments WHEN r.category = 'C' then SUM(r.payment) As C_payments END FROM r_invoiceTable As r GROUP BY r.id, r.category I have data where all of the above cases should be executed because the data that I have has A,B and C Sample Data- r_invoiceTable Id --- Category ---- Payment 222 A ---- 50 444 A ---- 30 111 B ---- 90 777 C ---- 20 555 C ---- 40 Desired Output A_payments = 80, B_payments = 90, C_payments = 60

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  • Ruby Methods: return an usage string when insufficient arguments are given

    - by Shyam
    Hi, After creating a serious bunch of classes, with initialize methods, loading them in IRb requires to look back at the code. However, I think it should be easy enough to return a usage message, instead of: ArgumentError: wrong number of arguments (0 for 9) So I prefer to return a string with the human readable arguments, by example using "puts" or just a return of a string. Now I have seen the rescue keyword inside begin-end code, but I wonder how I could catch the ArgumentError when the initialize method is called. Thank you for your answers, feedback and comments!

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  • How do I handle freeing unmanaged structures on application close?

    - by LostKaleb
    I have a C# project in which i use several unmanaged C++ functions. More so, I also have static IntPtr that I use as parameters for those functions. I know that whenever I use them, I should implement IDisposable in that class and use a destructor to invoke the Dispose method, where I free the used IntPtr, as is said in the MSDN page. public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } private void Dispose(bool disposing) { // Check to see if Dispose has already been called. if (!this.disposed) { if (disposing) { component.Dispose(); } CloseHandle(m_InstanceHandle); m_InstanceHandle = IntPtr.Zero; disposed = true; } } [System.Runtime.InteropServices.DllImport("Kernel32")] private extern static Boolean CloseHandle(IntPtr handle); However, when I terminate the application, I'm still left with a hanging process in TaskManager. I believe that it must be related to the used of the MarshalAs instruction in my structures: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; } When I create such a structure should I also be careful to free the space it allocs using a destructor? [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; ~SipxAudioCodec() { Marshal.FreeGlobal(something...); } }

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  • Correct usage of "<T extends SuperClass>"

    - by yusaku
    I am not familiar with "Generics". Is it a correct use of "<T extends SuperClass>" ? And do you agree that the codes after using generics are better? Before using Generics ================================================= public abstract class SuperSample { public void getSomething(boolean isProcessA) { doProcessX(); if(isProcessA){ doProcessY(new SubASample()); }else{ doProcessY(new SubBSample()); } } protected abstract void doProcessX(); protected void doProcessY(SubASample subASample) { // Nothing to do } protected void doProcessY(SubBSample subBSample) { // Nothing to do } } public class SubASample extends SuperSample { @Override protected void doProcessX() { System.out.println("doProcessX in SubASample"); } @Override protected void doProcessY(SubASample subASample) { System.out.println("doProcessY in SubASample"); } } public class Sample { public static void main(String[] args) { SubASample subASample = new SubASample(); subASample.getSomething(true); } } After using Generics ================================================= public abstract class SuperSample { public void getSomething(boolean isProcessA) { doProcessX(); if(isProcessA){ doProcessY(new SubASample()); }else{ doProcessY(new SubBSample()); } } protected abstract void doProcessX(); protected abstract <T extends SuperSample> void doProcessY(T subSample); } public class SubASample extends SuperSample { @Override protected void doProcessX() { System.out.println("doProcessX in SubASample"); } @Override protected <T extends SuperSample> void doProcessY(T subSample) { System.out.println("doProcessY in SubASample"); } } public class Sample { public static void main(String[] args) { SubASample subASample = new SubASample(); subASample.getSomething(true); } }

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  • MYSQL - REMOVE HTML TAGS from Record

    - by Dam
    Need help to form the MYSQL query from table one column having the bellow content Row1 : this is first <a href='mytext.txt'>row</a> from the table Row 2 : THis is the second row <img src ='mytext.jpg'> my image is there Row 3 : <p>This is the Third row my mytext is there </p> Row 4 : <p class='te_mytext'>This is the Third row my text is there </p> this is the table rows i try to search the keyword as 'mytext' my query is SELECT * from table WHERE colmn_name ` like '%mytext%' " i will get all the 4 rows as result but the result is wrong ..... need to get the correct output as only Row 3 the reason this row only having the mytext inside the content all other are not in content but mytext having in all rows how can i write the Query MYSQL please help me (NOT in PHP only MYSQL )

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  • Objective C Naming Convention for an object that owns itself

    - by Ed Marty
    With the latest releases of XCode that contain static analyzers, some of my objects are throwing getting analyzer issues reported. Specifically, I have an object that owns itself and is responsible for releasing itself, but should also be returned to the caller and possibly retained there manually. If I have a method like + (Foo) newFoo the analyzer sees the word New and reports an issue in the caller saying that newFoo is expected to return an object with retain +1, and it isn't being released anywhere. If I name it + (Foo) getFoo the analyzer reports an issue in that method, saying there's a potential leak because it's not deallocated before returning. My class basically looks like this: + (Foo *) newFoo { Foo *myFoo = [[[Foo new] retain] autorelease]; [myFoo performSelectorInBackground:@selector(bar) withObject:nil]; return myFoo; } - (void) bar { //Do something that might take awhile [self release]; } The object owns itself and when its done, will release itself, but there's nowhere that it's being stored, so the static analyzer sees it as a leak somewhere. Is there some naming or coding convention to help?

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  • When using a repository is it possible for a type to return a Func that the repository uses to test for existing entities?

    - by Scott Rickman
    For example given a Factory with a method public static T Save<T>(T item) where T : Base, new() { /* item.Id == Guid.Empty therefore item is new */ if (item.Id == Guid.Empty && repository.GetAll<T>(t => t.Name == item.Name)) { throw new Exception("Name is not unique"); } } how do I create a property of Base (say MustNotAlreadyExist) so that I can change the method above to public static T Save<T>(T item) where T : Base, new() { /* item.Id == Guid.Empty therefore item is new */ if (item.Id == Guid.Empty && repository.GetAll<T>(t.MustNotAlreadyExist)) { throw new Exception("Name is not unique"); } } public class Base { ... public virtual Expression<Func<T, bool>> MustNotAlreadyExist() { return (b => b.Name == name); /* <- this clearly doesn't work */ } } and then how can I override MustNotAlreadyExist in Account : Base public class Account : Base { ... public override Expression<Func<T, bool>> MustNotAlreadyExist() { return (b => b.Name == name && b.AccountCode == accountCode); /* <- this doesn't work */ } ... }

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  • Best way to run multiple queries per second on database, performance wise?

    - by Michael Joell
    I am currently using Java to insert and update data multiple times per second. Never having used databases with Java, I am not sure what is required, and how to get the best performance. I currently have a method for each type of query I need to do (for example, update a row in a database). I also have a method to create the database connection. Below is my simplified code. public static void addOneForUserInChannel(String channel, String username) throws SQLException { Connection dbConnection = null; PreparedStatement ps = null; String updateSQL = "UPDATE " + channel + "_count SET messages = messages + 1 WHERE username = ?"; try { dbConnection = getDBConnection(); ps = dbConnection.prepareStatement(updateSQL); ps.setString(1, username); ps.executeUpdate(); } catch(SQLException e) { System.out.println(e.getMessage()); } finally { if(ps != null) { ps.close(); } if(dbConnection != null) { dbConnection.close(); } } } And my DB connection private static Connection getDBConnection() { Connection dbConnection = null; try { Class.forName(DB_DRIVER); } catch (ClassNotFoundException e) { System.out.println(e.getMessage()); } try { dbConnection = DriverManager.getConnection(DB_CONNECTION, DB_USER,DB_PASSWORD); return dbConnection; } catch (SQLException e) { System.out.println(e.getMessage()); } return dbConnection; } This seems to be working fine for now, with about 1-2 queries per second, but I am worried that once I expand and it is running many more, I might have some issues. My questions: Is there a way to have a persistent database connection throughout the entire run time of the process? If so, should I do this? Are there any other optimizations that I should do to help with performance? Thanks

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  • very simple delegate musing

    - by Ted
    Sometimes the simplest questions make me love C/C++ and C# more and more. Today sitting on the bus musing aout delegates I remembered reading somwhere you don't need to use the new keyword when instaniating a new delegate. For example: public static void SomeMethod(string message) { ... } ... public delegate void TestDelgate(string message); //Define a delegate ........... //create a new instance ..METHOD 1 TestDelgate t = new TestDelgate(SomeMethod); //OR another way to create a new instance ..METHOD 2 TestDelgate t = SomeMethod; //create a new instance ..METHOD 2 So todays questions are What happens under the hood in method 2. Does the compiler expand method 2 into method 1, hence writing TestDelgate t = SomeMethod; is just a shortcut for TestDelgate t = new TestDelgate(SomeMethod);, or is there another reason for the exsitence of method 2 Do you guys think method 1 or method 2 is better for readability (this is a subjective question, but I'd just like to get a unscientific feel of general opinion of stackoverflow :-))

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  • How do I insert data into a object relational table with multiple ref in the schema.

    - by Yiling
    I have a table with a schema of Table(number, ref, ref, varchar2, varchar2,...). How would I insert a row of data into this table? When I do: "insert into table values (1, select ref(p), ref(d), '239 F.3d 1343', '35 USC § 283', ... from plaintiff p, defendant d where p.name='name1' and d.name='name2');" I get a "missing expression" error. If I do: "insert into table 1, select ref(p), ref(d), ... from plaintiff p, defendant where p.name=...;" I get a "missing keyword VALUES" error.

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