convenience methods - Page 434

Is it OK to put a standard, pure C header #include directive inside a namespace?

- by mic_e

I've got a project with a class log in the global namespace (::log). So, naturally, after #include <cmath>, the compiler gives an error message each time I try to instantiate an object of my log class, because <cmath> pollutes the global namespace with lots of three-letter methods, one of them being the logarithm function log(). So there are three possible solutions, each having their unique ugly side-effects. Move the log class to it's own namespace and always access it with it's fully qualified name. I really want to avoid this because the logger should be as convenient as possible to use. Write a mathwrapper.cpp file which is the only file in the project that includes <cmath>, and makes all the required <cmath> functions available through wrappers in a namespace math. I don't want to use this approach because I have to write a wrapper for every single required math function, and it would add additional call penalty (cancelled out partially by the -flto compiler flag) The solution I'm currently considering: Replace #include <cmath> by namespace math { #include "math.h" } and then calculating the logarithm function via math::log(). I have tried it out and it does, indeed, compile, link and run as expected. It does, however, have multiple downsides: It's (obviously) impossible to use <cmath>, because the <cmath> code accesses the functions by their fully qualified names, and it's deprecated to use in C++. I've got a really, really bad feeling about it, like I'm gonna get attacked and eaten alive by raptors. So my question is: Is there any recommendation/convention/etc that forbid putting include directives in namespaces? Could anything go wrong with diferent C standard library implementations (I use glibc), different compilers (I use g++ 4.7, -std=c++11), linking? Have you ever tried doing this? Are there any alternate ways to banish the math functions from the global namespace? I've found several similar questions on stackoverflow, but most were about including other C++ headers, which obviously is a bad idea, and those that weren't made contradictory statements about linking behaviour for C libraries. Also, would it be beneficial to additionally put the #include <math.h> inside extern "C" {}?

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C#: Object having two constructors: how to limit which properties are set together?

- by Dr. Zim

Say you have a Price object that accepts either an (int quantity, decimal price) or a string containing "4/$3.99". Is there a way to limit which properties can be set together? Feel free to correct me in my logic below. The Test: A and B are equal to each other, but the C example should not be allowed. Thus the question How to enforce that all three parameters are not invoked as in the C example? AdPrice A = new AdPrice { priceText = "4/$3.99"}; // Valid AdPrice B = new AdPrice { qty = 4, price = 3.99m}; // Valid AdPrice C = new AdPrice { qty = 4, priceText = "2/$1.99", price = 3.99m};// Not The class: public class AdPrice { private int _qty; private decimal _price; private string _priceText; The constructors: public AdPrice () : this( qty: 0, price: 0.0m) {} // Default Constructor public AdPrice (int qty = 0, decimal price = 0.0m) { // Numbers only this.qty = qty; this.price = price; } public AdPrice (string priceText = "0/$0.00") { // String only this.priceText = priceText; } The Methods: private void SetPriceValues() { var matches = Regex.Match(_priceText, @"^\s?((?<qty>\d+)\s?/)?\s?[$]?\s?(?<price>[0-9]?\.?[0-9]?[0-9]?)"); if( matches.Success) { if (!Decimal.TryParse(matches.Groups["price"].Value, out this._price)) this._price = 0.0m; if (!Int32.TryParse(matches.Groups["qty"].Value, out this._qty)) this._qty = (this._price > 0 ? 1 : 0); else if (this._price > 0 && this._qty == 0) this._qty = 1; } } private void SetPriceString() { this._priceText = (this._qty > 1 ? this._qty.ToString() + '/' : "") + String.Format("{0:C}",this.price); } The Accessors: public int qty { get { return this._qty; } set { this._qty = value; this.SetPriceString(); } } public decimal price { get { return this._price; } set { this._price = value; this.SetPriceString(); } } public string priceText { get { return this._priceText; } set { this._priceText = value; this.SetPriceValues(); } } }

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Calling a webservice synchronously from a Silverlight 3 application?

- by Lasse V. Karlsen

I am trying to reuse some .NET code that performs some calls to a data-access-layer type service. I have managed to package up both the input to the method and the output from the method, but unfortunately the service is called from inside code that I really don't want to rewrite in order to be asynchronous. Unfortunately, the webservice code generated in Silverlight only produces asynchronous methods, so I was wondering if anyone had working code that managed to work around this? I tried the recipe found here: The Easy Way To Synchronously Call WCF Services In Silverlight, but unfortunately it times out and never completes the call. Or rather, what seems to happen is that the completed event handler is called, but only after the method returns. I am suspecting that the event handler is called from a dispatcher or similar, and since I'm blocking the main thread here, it never completes until the code is actually back into the GUI loop. Or something like that. Here's my own version that I wrote before I found the above recipe, but it suffers from the same problem: public static object ExecuteRequestOnServer(Type dalInterfaceType, string methodName, object[] arguments) { string securityToken = "DUMMYTOKEN"; string input = "DUMMYINPUT"; object result = null; Exception resultException = null; object evtLock = new object(); var evt = new System.Threading.ManualResetEvent(false); try { var client = new MinGatServices.DataAccessLayerServiceSoapClient(); client.ExecuteRequestCompleted += (s, e) => { resultException = e.Error; result = e.Result; lock (evtLock) { if (evt != null) evt.Set(); } }; client.ExecuteRequestAsync(securityToken, input); try { var didComplete = evt.WaitOne(10000); if (!didComplete) throw new TimeoutException("A data access layer web service request timed out (" + dalInterfaceType.Name + "." + methodName + ")"); } finally { client.CloseAsync(); } } finally { lock (evtLock) { evt.Close(); evt = null; } } if (resultException != null) throw resultException; else return result; } Basically, both recipes does this: Set up a ManualResetEvent Hook into the Completed event The event handler grabs the result from the service call, and signals the event The main thread now starts the web service call asynchronously It then waits for the event to become signalled However, the event handler is not called until the method above has returned, hence my code that checks for evt != null and such, to avoid TargetInvocationException from killing my program after the method has timed out. Does anyone know: ... if it is possible at all in Silverlight 3 ... what I have done wrong above?

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Disable Dojo validation on certain fields

- by Eric LaForce

I would like to disable client side validation on certain fields in my user form. Currently I have two sets of fields that are displayed depending on the value of a previous drop down list. i.e. if the drop down list is set to value "A" 1 new field appears in the form. If the drop down list is set to value "B" 3 new fields appear in the form (mutually exclusive from the new form field when "A" is selected). Currently my Dojo client side validation fails because the fields that are not shown to the user (and thus no data can be inserted into those fields) fails to validate. Currently I determined that I can set the "validate" attribute to return true like so: <input type="text" id="companycity" name="companycity" class="textinput" value="<?php echo set_value('companycity'); ?>" style="<?php if(isset($errorData['companycity'])){echo $errorData['companycity'];} ?>" dojotype="dijit.form.ValidationTextBox" required="true" trim="true" validate='return true'" regexp="([a-zA-Z]{1,25})" invalidMessage="Invalid value. Must be between 1 and 25 alphabetic characters long."> This fixes my issue for hidden fields. However this now means that no validation is performed when this field becomes visible to the user (i.e. the validate attribute is still set to return true). I have tried removing the validate property when a field is displayed to the user like so: dijit.byId('companycode').attr('validate',''); This just set the attribute to nothing. This however gives errors in firebug saying validate method not found, so I take that to mean I did not remove this attribute correctly or removing this attribute is not the appropriate way to do this. I have also looked at overriding the validator method here but this doesnt seem like what I want either. I do not want to have to rewrite all the validation methods in place of dojo's. I just want dojo not to validate if the field is not visible to the user. Thanks for any advice or help.

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Instantiating custom PropertySourcesPlaceholderConfigurer from spring context

- by mmona

I want to define a custom PropertySourcesPlaceholderConfigurer in spring context xml. I want to use there multiple PropertySources, so that I can load part of the configuration from several property files and provide other part dynamically by my custom PropertySource implementation. The advantage is that it should be then easy to adjust the order of loading these property sources just by making modifications to the xml spring configuration. And here I run into a problem: how to define an arbitrary list of PropertySources and inject it into PropertySourcesPlaceholderConfigurer, so that it uses the sources defined by me? Seems to be a basic thing that should be provided by spring, but since yesterday I cannot find a way to do it. Using namespace would enable me to load several property files, but I also need to define the id of the PropertySourcesPlaceholderConfigurer (as other projects refer to it), and also I want to use my custom implementation. That is why I am defining the bean explicitly and not using the namespace. The most intuitive way would be to inject a list of PropertySources into PropertySourcesPlaceholderConfigurer like this: <bean id="applicationPropertyPlaceholderConfigurer" class="org.springframework.context.support.PropertySourcesPlaceholderConfigurer"> <property name="ignoreUnresolvablePlaceholders" value="true" /> <property name="ignoreResourceNotFound" value="true" /> <property name="order" value="0"/> <property name="propertySources"> <list>  </list> </property> </bean> but unfortunately propertySources is of type PropertySources and does not accept a list. The PropertySources interface has one and only implementor which is MutablePropertySources, which indeed stores list of PropertySource objects, but has no constructor nor setter through which I can inject this list. It only has add*(PropertySource) methods. The only workaround I see now is to implement my own PropertySources class, extending MutablePropertySources, which would accept list of PropertySource objects on creation and manually add it via using add*(PropertySource) method. But why so much workaround would be needed to provide something that I thought was supposed to be the main reason of introducing the PropertySources (having flexible configuration manageable from spring configuration level). Please clarify what am I getting wrong :)

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How to calculate where bullet hits

- by lkjoel

I have been trying to write an FPS in C/X11/OpenGL, but the issue that I have encountered is with calculating where the bullet hits. I have used a horrible technique, and it only sometimes works: pos size, p; size.x = 0.1; size.z = 0.1; // Since the game is technically top-down (but in a 3D perspective) // Positions are in X/Z, no Y float f; // Counter float d = FIRE_MAX + 1 /* Shortest Distance */, d1 /* Distance being calculated */; x = 0; // Index of object to hit for (f = 0.0; f < FIRE_MAX; f += .01) { // Go forwards p.x = player->pos.x + f * sin(toRadians(player->rot.x)); p.z = player->pos.z - f * cos(toRadians(player->rot.x)); // Get all objects that collide with the current position of the bullet short* objs = _colDetectGetObjects(p, size, objects); for (i = 0; i < MAX_OBJECTS; i++) { if (objs[i] == -1) { continue; } // Check the distance between the object and the player d1 = sqrt( pow((objects[i].pos.x - player->pos.x), 2) + pow((objects[i].pos.z - player->pos.z), 2)); // If it's closer, set it as the object to hit if (d1 < d) { x = i; d = d1; } } // If there was an object, hit it if (x > 0) { hit(&objects[x], FIRE_DAMAGE, explosions, currtime); break; } } It just works by making a for-loop and calculating any objects that might collide with where the bullet currently is. This, of course, is very slow, and sometimes doesn't even work. What would be the preferred way to calculate where the bullet hits? I have thought of making a line and seeing if any objects collide with that line, but I have no idea how to do that kind of collision detection. EDIT: I guess my question is this: How do I calculate the nearest object colliding in a line (that might not be a straight 45/90 degree angle)? Or are there any simpler methods of calculating where the bullet hits? The bullet is sort of like a laser, in the sense that gravity does not affect it (writing an old-school game, so I don't want it to be too realistic)

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How to use method hiding (new) with generic constrained class

- by ongle

I have a container class that has a generic parameter which is constrained to some base class. The type supplied to the generic is a sub of the base class constraint. The sub class uses method hiding (new) to change the behavior of a method from the base class (no, I can't make it virtual as it is not my code). My problem is that the 'new' methods do not get called, the compiler seems to consider the supplied type to be the base class, not the sub, as if I had upcast it to the base. Clearly I am misunderstanding something fundamental here. I thought that the generic where T: xxx was a constraint, not an upcast type. This sample code basically demonstrates what I'm talking about. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace GenericPartialTest { class ContextBase { public string GetValue() { return "I am Context Base: " + this.GetType().Name; } public string GetOtherValue() { return "I am Context Base: " + this.GetType().Name; } } partial class ContextSub : ContextBase { public new string GetValue() { return "I am Context Sub: " + this.GetType().Name; } } partial class ContextSub { public new string GetOtherValue() { return "I am Context Sub: " + this.GetType().Name; } } class Container<T> where T: ContextBase, new() { private T _context = new T(); public string GetValue() { return this._context.GetValue(); } public string GetOtherValue() { return this._context.GetOtherValue(); } } class Program { static void Main(string[] args) { Console.WriteLine("Simple"); ContextBase myBase = new ContextBase(); ContextSub mySub = new ContextSub(); Console.WriteLine(myBase.GetValue()); Console.WriteLine(myBase.GetOtherValue()); Console.WriteLine(mySub.GetValue()); Console.WriteLine(mySub.GetOtherValue()); Console.WriteLine("Generic Container"); Container<ContextBase> myContainerBase = new Container<ContextBase>(); Container<ContextSub> myContainerSub = new Container<ContextSub>(); Console.WriteLine(myContainerBase.GetValue()); Console.WriteLine(myContainerBase.GetOtherValue()); Console.WriteLine(myContainerSub.GetValue()); Console.WriteLine(myContainerSub.GetOtherValue()); Console.ReadKey(); } } }

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sqlite 3 opening issue

- by anonymous

I'm getting my data ,with several similar methods, from sqlite3 file like in following code: -(NSMutableArray *) getCountersByID:(NSString *) championID{ NSMutableArray *arrayOfCounters; arrayOfCounters = [[NSMutableArray alloc] init]; @try { NSFileManager *fileManager = [NSFileManager defaultManager]; NSString *databasePath = [[[NSBundle mainBundle] resourcePath ]stringByAppendingPathComponent:@"DatabaseCounters.sqlite"]; BOOL success = [fileManager fileExistsAtPath:databasePath]; if (!success) { NSLog(@"cannot connect to Database! at filepath %@",databasePath); } else{ NSLog (@"SUCCESS getCountersByID!!"); } if(sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK){ NSString *tempString = [NSString stringWithFormat:@"SELECT COUNTER_ID FROM COUNTERS WHERE CHAMPION_ID = %@",championID]; const char *sql = [tempString cStringUsingEncoding:NSASCIIStringEncoding]; sqlite3_stmt *sqlStatement; int ret = sqlite3_prepare(database, sql, -1, &sqlStatement, NULL); if (ret != SQLITE_OK) { NSLog(@"Error calling sqlite3_prepare: %d", ret); } if(sqlite3_prepare_v2(database, sql, -1, &sqlStatement, NULL) == SQLITE_OK){ while (sqlite3_step(sqlStatement)==SQLITE_ROW) { counterList *CounterList = [[counterList alloc]init]; CounterList.counterID = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement,0)]; [arrayOfCounters addObject:CounterList]; } } else{ NSLog(@"problem with database prepare"); } sqlite3_finalize(sqlStatement); } else{ NSLog(@"problem with database openning %s",sqlite3_errmsg(database)); } } @catch (NSException *exception){ NSLog(@"An exception occured: %@", [exception reason]); } @finally{ sqlite3_close(database); return arrayOfCounters; } //end } then i'm getting access to data with this and other similar lines of code: myCounterList *MyCounterList = [[myCounterList alloc] init]; countersTempArray = [MyCounterList getCountersByID:"2"]; [countersArray addObject:[NSString stringWithFormat:@"%@",(((counterList *) [countersTempArray objectAtIndex:i]).counterID)]]; I'm getting a lot of data like image name and showing combination of them that depends on users input with such code: UIImage *tempImage = [UIImage imageNamed:[NSString stringWithFormat:@"%@_0.jpg",[countersArray objectAtIndex:0]]]; [championSelection setBackgroundImage:tempImage forState:UIControlStateNormal]; My problem: When i'm run my app for some time and get a lot of data it throws error: " problem with database openning unable to open database file - error = 24 (Too many open files)" My guess is that i'm opening my database every time when getCountersByID is called but not closing it. My question: Am i using right approach to open and close database that i use? Similar questions that have not helped me to solve this problem: unable to open database Sqlite Opening Error : Unable to open database UPDATE: I made assumption that error is showing up because i use this lines of code too much: NSFileManager *fileManager = [NSFileManager defaultManager]; NSString *databasePath = [[[NSBundle mainBundle] resourcePath ]stringByAppendingPathComponent:@"DatabaseCounters.sqlite"]; BOOL success = [fileManager fileExistsAtPath:databasePath]; and ending up with error 24. So i made them global but sqlite3_errmsg shows same err 24, but app runs much faster now I'll try to debug my app, see what happens

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C# ATM Bank coding help needed please

- by user1735692

if anyone can help with with I would be grateful. I am trying to make a program in c# that acts like an ATM with withdrawing, depositing money, displayed in Program.cs that is connected to Account.cs linked class programs. At the moment it works if I manually input the data and tell it what to display, but I what to do is - Allow users to enter amounts to deposit and withdraw using overloaded implementations of the methods makeDeposit and makeWithdrawal. I have tried many things, and can not get it to work, if anyone can help, I would be grateful if anyone can, thanks again Program.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Tut9 { class Program { static void Main(string[] args) { Account myAcc = new Account(); myAcc.makeDeposit(10000); myAcc.showBalance(); Console.WriteLine("Attempting to withdraw £" + 90); myAcc.makeWithdrawal(90); myAcc.showBalance(); myAcc.giveOverdraft(50); myAcc.showBalance(); Account student = new Account(30, -100); student.giveOverdraft(-500); } } } Account.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Tut9 { class Account { ////Need to know the balance & ovedraft private int balance; private int overdraft; ////Constructor public Account() { balance = 0; overdraft = 0; } public Account(int initial) { balance = initial; } public Account(int intial, int over) { balance = intial; overdraft = over; } public void giveOverdraft(int amount) { overdraft = amount; } ////Method to display the balance & overdraft public void showBalance() { Console.WriteLine("The balance is now £" + balance); if (overdraft != 0) { Console.WriteLine("You have an overdraft of £" + overdraft); } } ////Method to make a withdrawl public void makeWithdrawal(int y) { balance = balance - y; Console.WriteLine("Withdrew £" + y); } ////Method to make deposit public void makeDeposit(int x) { balance = balance + x; Console.WriteLine("Desposited £" + x); } } }

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How to write php code to input jsonstring and insert to sql server

- by Romi

i am trying to OUTPUT a Json String from the phone and to get it uploaded to the sql server i have. I Do not know how to get the output Json and write the php code... i tried many methods but couldnt find a solution. public void post(String string) { HttpClient httpclient = new DefaultHttpClient(); HttpPost httppost = new HttpPost( "http://www.hopscriber.com/xoxoxox/testphp.php"); try { List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(); nameValuePairs.add(new BasicNameValuePair("myJson", string)); httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); HttpResponse response = httpclient.execute(httppost); String str = inputStreamToString(response.getEntity().getContent()) .toString(); Log.w("SENCIDE", str); } catch (Exception e) { Toast.makeText(getBaseContext(), "notwork", Toast.LENGTH_LONG) .show(); } } private Object inputStreamToString(InputStream is) { // TODO Auto-generated method stub String line = ""; StringBuilder total = new StringBuilder(); // Wrap a BufferedReader around the InputStream BufferedReader rd = new BufferedReader(new InputStreamReader(is)); // Read response until the end try { while ((line = rd.readLine()) != null) { total.append(line); } } catch (IOException e) { e.printStackTrace(); } // Return full string return total; } it outputs a json string as [myJson=[{"name":"FriendTracker","user":"amjgp000000000000000","pack":"org.siislab.tutorial.friendtracker","perm":"org.siislab.tutorial.permission.READ_FRIENDS","level":"Normal"},{"name":"FriendTracker","user":"amjgp000000000000000","pack":"org.siislab.tutorial.friendtracker","perm":"org.siislab.tutorial.permission.WRITE_FRIENDS","level":"Normal"},{"name":"FriendTracker","user":"amjgp000000000000000","pack":"org.siislab.tutorial.friendtracker","perm":"org.siislab.tutorial.permission.FRIEND_SERVICE","level":"Normal"},{"name":"FriendTracker","user":"amjgp000000000000000","pack":"org.siislab.tutorial.friendtracker","perm":"org.siislab.tutorial.permission.FRIEND_NEAR","level":"Dangerous"},{"name":"FriendTracker","user":"amjgp000000000000000","pack":"org.siislab.tutorial.friendtracker","perm":"org.siislab.tutorial.permission.BROADCAST_FRIEND_NEAR","level":"Normal"},{"name":"FriendTracker","user":"amjgp000000000000000","pack":"org.siislab.tutorial.friendtracker","perm":"android.permission.RECEIVE_BOOT_COMPLETED","level":"Normal"},{"name":"FriendTracker","user":"amjgp000000000000000","pack":"org.siislab.tutorial.friendtracker","perm":"android.permission.READ_CONTACTS","level":"Dangerous"},{"name":"FriendTracker","user":"amjgp000000000000000","pack":"org.siislab.tutorial.friendtracker","perm":"android.permission.ACCESS_FINE_LOCATION","level":"Dangerous"},{"name":"FriendTracker","user":"amjgp000000000000000","pack":"org.siislab.tutorial.friendtracker","perm":"android.permission.WRITE_EXTERNAL_STORAGE","level":"Dangerous"},{"name":"FriendTracker","user":"amjgp000000000000000","pack":"org.siislab.tutorial.friendtracker","perm":"android.permission.READ_PHONE_STATE","level":"Dangerous"},{"name":"Tesing","user":"amjgp000000000000000","pack":"com.example.tesing","perm":"null","level":"null"},{"name":"Action Bar","user":"amjgp000000000000000","pack":"name.brucephillips.actionbarexample","perm":"null","level":"null"},.......

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Line Graph CGPoints from NSMutableArray

- by Mattog1456

I have been trying to adapt the code from the accelerometer example such that when the user depresses a uibutton a point is added to a line graph. Working on the converting two floats, which are the result of calculate as below into a CGPoint and converting the CGPoint into an NSValue and then adding this to a NSMutableArray with the following -(IBAction)calculate:(id)sender { self.points = [NSMutableArray array]; CGPoint pt = CGPointMake(d, c); [self.points addObject:[NSValue valueWithCGPoint:pt]]; NSLog(@"%@", NSStringFromCGPoint(pt)); NSLog(@"%@", [NSString stringWithFormat:@"%d points", self.points.count ]); } But for some reason I am only getting one object stored in the array, it seems everytime push the calculate button the object pt gets overwritten, on the plus side it has the correct x,y coords. Any ideas on this one? UPDATE Removed self.points = [NSMutableArray array]; and placed it in view did load, also set the first points to 0,0. so that is working ok. Now the next problem is that I have a Graph subclass where the CG Drawing is taking place. I am trying to figure out a simple way to be able to access the above NSMutableArray which is in a ViewController class from the graph class. Am so close to the end but am really stuck, any help would be great. Still trying to draw a line graph on a UIView which is on a UIScrollview. The draw rect method is in the UIView Subclass and everything is working there, I have gridlines and labels on the axis and I can draw manually onto it. But the problem I have is that I cannot read the NSMutableArray of the CGPoints, which are the x and y coords. The ViewController performs a calculation and the results are written to the NSMutable array and this is all working fine as well, I can see the CGpoints and their values being written with NSLogs in the ViewController. I have tried various ways to set the NSMutableArray up as a global but to no avail, everything runs but while I can see the points being written in the ViewController they are just not visible to the UIView Subclass. I have also tried to use the addObserver and observeValueForKeyPath methods and once again while everything runs the subclass cannot see the array. Any ideas, suggestions, tips or thoughts would be great

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why my test performance class gives me inconsistent results even after proper warm-up?

- by colinfang

i made a class which helps me measure time for any methods in Ticks. Basically, it runs testing method 100x, and force GC, then it records time taken for another 100x method runs. x64 release ctrl+f5 VS2012/VS2010 the results are following: 2,914 2,909 2,913 2,909 2,908 2,907 2,909 2,998 2,976 2,855 2,446 2,415 2,435 2,401 2,402 2,402 2,399 2,401 2,401 2,400 2,399 2,400 2,404 2,402 2,401 2,399 2,400 2,402 2,404 2,403 2,401 2,403 2,401 2,400 2,399 2,414 2,405 2,401 2,407 2,399 2,401 2,402 2,401 2,404 2,401 2,404 2,405 2,368 1,577 1,579 1,626 1,578 1,576 1,578 1,577 1,577 1,576 1,578 1,576 1,578 1,577 1,578 1,576 1,578 1,577 1,579 1,585 1,576 1,579 1,577 1,579 1,578 1,579 1,577 1,578 1,577 1,578 1,576 1,578 1,577 1,578 1,599 1,579 1,578 1,582 1,576 1,578 1,576 1,579 1,577 1,578 1,577 1,591 1,577 1,578 1,578 1,576 1,578 1,576 1,578 As you can see there are 3 phases, first is ~2,900, second is ~2,400, then ~1,550 What might be the reason to cause it? the test performance class code follows: public static void RunTests(Func<long> myTest) { const int numTrials = 100; Stopwatch sw = new Stopwatch(); double[] sample = new double[numTrials]; Console.WriteLine("Checksum is {0:N0}", myTest()); sw.Start(); myTest(); sw.Stop(); Console.WriteLine("Estimated time per test is {0:N0} ticks\n", sw.ElapsedTicks); for (int i = 0; i < numTrials; i++) { myTest(); } GC.Collect(); string testName = myTest.Method.Name; Console.WriteLine("----> Starting benchmark {0}\n", myTest.Method.Name); for (int i = 0; i < numTrials; i++) { sw.Restart(); myTest(); sw.Stop(); sample[i] = sw.ElapsedTicks; } double testResult = DataSetAnalysis.Report(sample); for (int j = 0; j < numTrials; j = j + 5) Console.WriteLine("{0,8:N0} {1,8:N0} {2,8:N0} {3,8:N0} {4,8:N0}", sample[j], sample[j + 1], sample[j + 2], sample[j + 3], sample[j + 4]); Console.WriteLine("\n----> End of benchmark"); }

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Encapsulating a Windows.Forms.Button

- by devoured elysium

I want to define a special kind of button that only allows two possible labels: "ON" and "OFF". I decided to inherit from a Windows.Forms.Button to implement this but now I don't know I how should enforce this rule. Should I just override the Text property like this? public override string Text { set { throw new InvalidOperationException("Invalid operation on StartStopButton!"); } } The problem I see with this is that I am breaking the contract that all buttons should have. If any code tries something like foreach (Button button in myForm) { button.Text = "123"; } they will get an Exception if I have any of my special buttons on the form, which is something that isn't expectable. First, because people think of properties just as "public" variables, not methods, second, because they are used to using and setting whatever they want to buttons without having to worry with Exceptions. Should I instead just make the set property do nothing? That could also lead to awkward results: myButton.Text = "abc"; MessageBox.Show(abc); //not "abc"! The general idea from the OO world is to in this kind of cases use Composition instead of inheritance. public class MySpecialButton : <Some class from System.Windows.Forms that already knows how to draw itself on forms> private Button button = new Button(); //I'd just draw this button on this class //and I'd then only show the fields I consider //relevant to the outside world. ... } But to make the Button "live" on a form it must inherit from some special class. I've looked on Control, but it seems to already have the Text property defined. I guess the ideal situation would be to inherit from some kind of class that wouldn't even have the Text property defined, but that'd have position, size, etc properties available. Upper in the hierarchy, after Control, we have Component, but that looks like a really raw class. Any clue about how to achieve this? I know this was a long post :( Thanks

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Android java assigning 2d array to 3d array

- by semajhan

I'm running into problems trying to assign a 2d array to a 3d array, so I thought i'd ask a question about 3d and 2d arrays. Say I have a masterArray[][][] and wanted to put childArray1[][] and childArray2[][] into it. This is how I have done it and was wondering if that is the correct way of applying it: private int[][][] masterArray; private int[][] childArray1 = { {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, {1, 1, 1, 0, 0, 1, 0, 1, 1, 1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, {1, 0, 1, 1, 1, 1, 1, 1, 0, 1}, {1, 0, 1, 1, 1, 1, 0, 1, 0, 1}, {1, 0, 1, 1, 0, 1, 0, 1, 0, 1}, {1, 0, 1, 1, 0, 1, 1, 1, 0, 1}, {1, 0, 1, 1, 1, 1, 1, 1, 0, 1}, {1, 0, 1, 1, 0, 1, 1, 1, 0, 1}, {1, 0, 1, 1, 0, 1, 8, 1, 0, 1}, {1, 0, 7, 1, 1, 1, 0, 1, 0, 1}, {1, 0, 1, 1, 1, 1, 0, 1, 0, 1}, {1, 0, 1, 1, 1, 1, 1, 1, 0, 1}, {1, 0, 0, 0, 0, 0, 0, 9, 0, 1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1} }; private int[][] childArray2 = { {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, {0, 0, 0, 0, 0, 0, 0, 0, 1, 1}, {1, 1, 1, 1, 7, 1, 1, 1, 1, 1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, {1, 1, 1, 1, 0, 1, 1, 1, 1, 1}, {1, 1, 1, 1, 0, 0, 0, 1, 1, 1}, {1, 1, 1, 9, 1, 1, 8, 0, 1, 1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, }; Ok, so in my init method I use these some methods to set the child arrays into the master array. What I was curious about was how this exactly works. I assumed the following: masterLevel = new int[MAX_LEVELS][MAP_WIDTH][MAP_HEIGHT]; for (int x = 0; x < MAP_WIDTH; x++) { for (int y = 0; y < MAP_HEIGHT; y++) { masterArray[currentLevel][x][y] = childArray1[x][y]; } } Would that work? In my application things aren't working so I picking out code that I am not 100% sure on.

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My webpage ignores changes in CSS file

- by Pavel

No matter what I change in my .css file, the page remains the same - what's more, neither changing the link tag so that it points to another .css file nor deleting it completely makes no difference. Other changes in html code are applied. The sourcecode of the webpage shows everything as it should be. This behavior started when I redirected the link tag from previous file to the one I use now (plus there have been some changes in the tag while this problem occured, to test the behavior of my webpage); changes in neither file affect the page. For the first time when this happened, this was caused by copies of head tag in included chunks of code (for header, left menu etc. - their head part overrode the head part of the main page) and the problem was solved by removing these redundant heads from these files. But it happened again when I changed the link tag for the next time. I couldn't find any head parts in my included files, but the problem lasts (only solution I can see now is to delete the included files and copy the code directly to the file, but this would mean lots of redundant code). How can I solve this problem, so that my page response to changes in .css files without increasing redundancy? How to ensure that I can change the link to .css file just on one place with no such problems? Do I have to unload the CSS file somehow? I saw this problem both in Firefox and in Chrome. I use PSPad to write the code, just in case it would play role. EDIT: I have cleared browser cache now, and I changed the link to .css files from one to another before, but nothing helped. Now I accept the best answer saying the problem is in caching and I start a related question to find out how to solve the caching issue. If the other question's answers would say that in this case I can be sure that problem isn't in caching (very unlikely, but fail of ordinary methods of caching-problems-solving is unlikely too), I'd update this question and start searching for other possible problems, but now the message seems to be clear: when webpage ignores changes in .css files, caching is to blame.

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Terminating a long-executing thread and then starting a new one in response to user changing parameters via UI in an applet

- by user1817170

I have an applet which creates music using the JFugue API and plays it for the user. It allows the user to input a music phrase which the piece will be based on, or lets them choose to have a phrase generated randomly. I had been using the following method (successfully) to simply stop and start the music, which runs in a thread using the Player class from JFugue. I generate the music using my classes and user input from the applet GUI...then... private playerThread pthread; private Thread threadPlyr; private Player player; (from variables declaration) public void startMusic(Pattern p) // pattern is a JFugue object which holds the generated music { if (pthread == null) { pthread = new playerThread(); } else { pthread = null; pthread = new playerThread(); } if (threadPlyr == null) { threadPlyr = new Thread(pthread); } else { threadPlyr = null; threadPlyr = new Thread(pthread); } pthread.setPattern(p); threadPlyr.start(); } class playerThread implements Runnable // plays midi using jfugue Player { private Pattern pt; public void setPattern(Pattern p) { pt = p; } @Override public void run() { try { player.play(pt); // takes a couple mins or more to execute resetGUI(); } catch (Exception exception) { } } } And the following to stop music when user presses the stop/start button while Player.isPlaying() is true: public void stopMusic() { threadPlyr.interrupt(); threadPlyr = null; pthread = null; player.stop(); } Now I want to implement a feature which will allow the user to change parameters while the music is playing, create an updated music pattern, and then play THAT pattern. Basically, the idea is to make it simulate "real time" adjustments to the generated music for the user. Well, I have been beating my head against the wall on this for a couple of weeks. I've read all the standard java documentation, researched, read, and searched forums, and I have tried many different ideas, none of which have succeeded. The problem I've run into with all approaches I've tried is that when I start the new thread with the new, updated musical pattern, all the old threads ALSO start, and there is a cacophony of unintelligible noise instead of my desired output. From what I've gathered, the issue seems to be that all the methods I've come across require that the thread is able to periodically check the value of a "flag" variable and then shut itself down from within its "run" block in response to that variable. However, since my thread makes a call that takes several minutes minimum to execute (playing the music), and I need to terminate it WHILE it is executing this, there is really no safe way to do so. So, I'm wondering if there is something I'm missing when it comes to threads, or if perhaps I can accomplish my goal using a totally different approach. Any ideas or guidance is greatly appreciated! Thank you!

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Can SQLite file copied successfully on the data folder of an unrooted android device ?

- by student

I know that in order to access the data folder on the device, it needs to be rooted. However, if I just want to copy the database from my assets folder to the data folder on my device, will the copying process works on an unrooted phone? The following is my Database Helper class. From logcat, I can verify that the methods call to copyDataBase(), createDataBase() and openDataBase() are returned successfully. However, I got this error message android.database.sqlite.SQLiteException: no such table: TABLE_NAME: when my application is executing rawQuery. I'm suspecting the database file is not copied successfully (cannot be too sure as I do not have access to data folder), yet the method call to copyDatabase() are not throwing any exception. What could it be? Thanks. ps: My device is still unrooted, I hope it is not the main cause of the error. public DatabaseHelper(Context context) { super(context, DB_NAME, null, 1); this.myContext = context; } public void createDataBase() throws IOException{ boolean dbExist = checkDataBase(); String s = new Boolean(dbExist).toString(); Log.d("dbExist", s ); if(dbExist){ //do nothing - database already exist Log.d("createdatabase","DB exists so do nothing"); }else{ this.getReadableDatabase(); try { copyDataBase(); Log.d("copydatabase","Successful return frm method call!"); } catch (IOException e) { throw new Error("Error copying database"); } } } private boolean checkDataBase(){ File dbFile = new File(DB_PATH + DB_NAME); return dbFile.exists(); } private void copyDataBase() throws IOException{ //Open your local db as the input stream InputStream myInput = null; myInput = myContext.getAssets().open(DB_NAME); Log.d("copydatabase","InputStream successful!"); // Path to the just created empty db String outFileName = DB_PATH + DB_NAME; //Open the empty db as the output stream OutputStream myOutput = new FileOutputStream(outFileName); //transfer bytes from the inputfile to the outputfile byte[] buffer = new byte[1024]; int length; while ((length = myInput.read(buffer))>0){ myOutput.write(buffer, 0, length); } //Close the streams myOutput.flush(); myOutput.close(); myInput.close(); } public void openDataBase() throws SQLException{ //Open the database String myPath = DB_PATH + DB_NAME; myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); } /* @Override public synchronized void close() { if(myDataBase != null) myDataBase.close(); super.close(); }*/ public void close() { // NOTE: openHelper must now be a member of CallDataHelper; // you currently have it as a local in your constructor if (myDataBase != null) { myDataBase.close(); } } @Override public void onCreate(SQLiteDatabase db) { } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { } }

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Second query to SQLite (on iPhone) errors.

- by Luke

Hi all, On the iPhone, I am developing a class for a cart that connects directly to a database. To view the cart, all items can be pulled from the database, however, it seems that removing them doesn't work. It is surprising to me because the error occurs during connection to the database, except not the second time I connect even after the DB has been closed. #import "CartDB.h" #import "CartItem.h" @implementation CartDB @synthesize database, databasePath; - (NSMutableArray *) getAllItems { NSMutableArray *items = [[NSMutableArray alloc] init]; if([self openDatabase]) { const char *sqlStatement = "SELECT * FROM items;"; sqlite3_stmt *compiledStatement; if(sqlite3_prepare_v2(cartDatabase, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) { while(sqlite3_step(compiledStatement) == SQLITE_ROW) { int rowId = sqlite3_column_int(compiledStatement, 0); int productId = sqlite3_column_int(compiledStatement, 1); NSString *features = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 2)]; int quantity = sqlite3_column_int(compiledStatement, 3); CartItem *cartItem = [[CartItem alloc] initWithRowId:rowId productId:productId features:features quantity:quantity]; [items addObject:cartItem]; [cartItem release]; } } sqlite3_finalize(compiledStatement); } [self closeDatabase]; return items; } - (BOOL) removeCartItem:(CartItem *)item { sqlite3_stmt *deleteStatement; [self openDatabase]; const char *sql = "DELETE FROM items WHERE id = ?"; if(sqlite3_prepare_v2(cartDatabase, sql, -1, &deleteStatement, NULL) != SQLITE_OK) { return NO; } sqlite3_bind_int(deleteStatement, 1, item.rowId); if(SQLITE_DONE != sqlite3_step(deleteStatement)) { sqlite3_reset(deleteStatement); [self closeDatabase]; return NO; } else { sqlite3_reset(deleteStatement); [self closeDatabase]; return YES; } } - (BOOL) openDatabase { if(sqlite3_open([databasePath UTF8String], &cartDatabase) == SQLITE_OK) { return YES; } else { return NO; } } - (void) closeDatabase { sqlite3_close(cartDatabase); } The error occurs on the line where the connection is opened in openDatabase. Any ideas? Need to flush something? Something gets autoreleased? I really can't figure it out. --Edit-- The error that I receive is GDB: Program received signal "EXC_BAD_ACCESS". --Edit-- I ended up just connecting in the init and closing in the free methods, which might not be the proper way, but that's another question altogether so it's effectively persistent instead of connecting multiple times. Still would be nice to know what was up with this for future reference.

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String.valueOf(int value) gives error [closed]

- by Davidrd91

I am trying to convert an int into a String so that I can put the String values into an SQLite Cursor. I've tried multiple syntax and methods but none seem to work for me. The Error occurs in MangaItemDB() while trying to convert any Int types aswell as the boolean. I've looked through several articles like this one but none works for me. Here's my code: public class MangaItem { private int _id; private String mangaName; private String mangaLink; private static String mangaAlpha; private static int mangaCount; private static int alphaCount; private boolean mangaComplete = false; public MangaItem MangaItemDB(int id, String mangaName, String mangaLink, String mangaAlpha, String mangaCount, String alphaCount, String mangaComplete) { MangaItem MangaItemDB = new MangaItem(); MangaItemDB._id = id; MangaItemDB.mangaName = mangaName; MangaItemDB.mangaLink = mangaLink; MangaItemDB.mangaAlpha = mangaAlpha; MangaItemDB.mangaCount = String.valueOf(int mangaCount); MangaItemDB.alphaCount = Integer.toString(getAlphaCount()); MangaItemDB.mangaComplete = String.valueOf(getMangaComplete()); return MangaItemDB; } public void incrementMangaCount() { mangaCount++; } public int getMangaCount() { return mangaCount; } public void incrementAlphaCount() { alphaCount++; } public int getAlphaCount() { return alphaCount; } public boolean setMangaComplete(boolean mangaComplete) { return true; } public boolean getMangaComplete() { return mangaComplete; } /** * @return the mangaName */ public String getMangaName() { return mangaName; } /** * @param mangaName the mangaName to set */ public void setMangaName(String mangaName) { this.mangaName = mangaName; } /** * @return the mangaLink */ public String getMangaLink() { return mangaLink; } /** * @param mangaLink the mangaLink to set */ public void setMangaLink(String mangaLink) { this.mangaLink = mangaLink; } /** * @return the mangaAlpha */ public String getMangaAlpha() { return mangaAlpha; } /** * @param mangaAlpha the mangaAlpha to set */ public void setMangaAlpha(String mangaAlpha) { this.mangaAlpha = mangaAlpha; } /** * @return the _id */ public int get_id() { return _id; } /** * @param _id the _id to set */ public void set_id(int _id) { this._id = _id; } } The lines : MangaItemDB.mangaCount = String.valueOf(mangaCount); MangaItemDB.alphaCount = Integer.toString(getAlphaCount()); MangaItemDB.mangaComplete = String.valueOf(getMangaComplete()); all give "Type mismatch: cannot convert from String to Int"

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Java Sorting "queue" list based on DateTime and Z Position (part of school project)

- by Kuchinawa

For a school project i have a list of 50k containers that arrive on a boat. These containers need to be sorted in a list in such a way that the earliest departure DateTimes are at the top and the containers above those above them. This list then gets used for a crane that picks them up in order. I started out with 2 Collection.sort() methods: 1st one to get them in the right XYZ order Collections.sort(containers, new Comparator<ContainerData>() { @Override public int compare(ContainerData contData1, ContainerData contData2) { return positionSort(contData1.getLocation(),contData2.getLocation()); } }); Then another one to reorder the dates while keeping the position in mind: Collections.sort(containers, new Comparator<ContainerData>() { @Override public int compare(ContainerData contData1, ContainerData contData2) { int c = contData1.getLeaveDateTimeFrom().compareTo(contData2.getLeaveDateTimeFrom()); int p = positionSort2(contData1.getLocation(), contData2.getLocation()); if(p != 0) c = p; return c; } }); But i never got this method to work.. What i got working now is rather quick and dirty and takes a long time to process (50seconds for all 50k): First a sort on DateTime: Collections.sort(containers, new Comparator<ContainerData>() { @Override public int compare(ContainerData contData1, ContainerData contData2) { return contData1.getLeaveDateTimeFrom().compareTo(contData2.getLeaveDateTimeFrom()); } }); Then a correction function that bumps top containers up: containers = stackCorrection(containers); private static List<ContainerData> stackCorrection(List<ContainerData> sortedContainerList) { for(int i = 0; i < sortedContainerList.size(); i++) { ContainerData current = sortedContainerList.get(i); // 5 = Max Stack (0 index) if(current.getLocation().getZ() < 5) { //Loop through possible containers above current for(int j = 5; j > current.getLocation().getZ(); --j) { //Search for container above for(int k = i + 1; k < sortedContainerList.size(); ++k) if(sortedContainerList.get(k).getLocation().getX() == current.getLocation().getX()) { if(sortedContainerList.get(k).getLocation().getY() == current.getLocation().getY()) { if(sortedContainerList.get(k).getLocation().getZ() == j) { //Found -> move container above current sortedContainerList.add(i, sortedContainerList.remove(k)); k = sortedContainerList.size(); i++; } } } } } } return sortedContainerList; } I would like to implement this in a better/faster way. So any hints are appreciated. :)

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Can I use accepts_nested_attributes_for with checkboxes in a _form to select potential 'links' from a list

- by Ryan

In Rails 3: I have the following models: class System has_many :input_modes # name of the table with the join in it has_many :imodes, :through => :input_modes, :source => 'mode', :class_name => "Mode" has_many :output_modes has_many :omodes, :through => :output_modes, :source => 'mode', :class_name => 'Mode' end class InputMode # OutputMode is identical belongs_to :mode belongs_to :system end class Mode ... fields, i.e. name ... end That works nicely and I can assign lists of Modes to imodes and omodes as intended. What I'd like to do is use accepts_nested_attributes_for or some other such magic in the System model and build a view with a set of checkboxes. The set of valid Modes for a given System is defined elsewhere. I'm using checkboxes in the _form view to select which of the valid modes is actually set in imodes and omodes . I don't want to create new Modes from this view, just select from a list of pre-defined Modes. Below is what I'm currently using in my _form view. It generates a list of checkboxes, one for each allowed Mode for the System being edited. If the checkbox is ticked then that Mode is to be included in the imodes list. <% @allowed_modes.each do |mode| %> <li> <%= check_box_tag :imode_ids, mode.id, @system.imodes.include?(modifier), :name => 'imode_ids[]' %> <%= mode.name %> </li> <% end %> Which passes this into the controller in params: { ..., "imode_ids"=>["2", "14"], ... } In the controller#create I extract and assign the Modes that had their corresponding checkboxes ticked and add them to imodes with the following code: @system = System.new(params[:system]) # Note the the empty list that makes sure we clear the # list if none of the checkboxes are ticked if params.has_key?(:imode_ids) imodes = Mode.find(params[:imode_ids]) else imodes = [] end @system.imodes = imodes Once again that all works nicely but I'll have to copy that cludgey code into the other methods in the controller and I'd much prefer to use something more magical if possible. I feel like I've passed off the path of nice clean rails code and into the forest of "hacking around" rails; it works but I don't like it. What should I have done?

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Name hiding from inherited classes

- by Mercerbearman

I have the following sample code and I wanted to know the correct way to get access to the Pass method in the CBar class. Currently I have found 3 ways to get access to this method and they are as follows: Casting the object, ((CBar *) &foo)-Pass(1, 2, 3); Using this syntax, foo.CBar::Pass(1,2,3); Use the "using" syntax in the CFoo class declaration, using CBar::Pass. The following is an example of a simple project to test this capability. Foo.h #include "bar.h" class CFoo : public CBar { private: double m_a; double m_b; public: CFoo(void); ~CFoo(void); void Pass(double a, double b); }; Foo.cpp #include "Foo.h" CFoo::CFoo(void) { m_a = 0.0; m_b = 0.0; } CFoo::~CFoo(void) { } void CFoo::Pass(double a, double b) { m_a = a; m_b = b; } Bar.h class CBar { int m_x; int m_y; int m_z; public: CBar(void); ~CBar(void); void Pass(int x, int y, int z); }; Bar.cpp #include "Bar.h" CBar::CBar(void) { m_x = 0; m_y = 0; m_z = 0; } CBar::~CBar(void) { } void CBar::Pass(int x, int y, int z) { m_x = x; m_y = y; m_z = z; } And my main class DoStuff.cpp #include "DoStuff.h" #include "Foo.h" CDoStuff::CDoStuff(void) { } CDoStuff::~CDoStuff(void) { } int main() { CFoo foo, foo1, foo2; //This only gets to the Pass method in Foo. foo.Pass(2.5, 3.5); //Gets access to Pass method in Bar. foo1.CBar::Pass(5,10,15); //Can also case and access by location for the same result?? ((CBar *) &foo2)->Pass(100,200,300); return 0; } Are each of these options viable? Are some preferred? Are there pitfalls with using any one of the methods listed? I am especially curious about the foo.CBar::Pass(1,2,3) syntax. Thanks, B

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How to see if type is instance of a class in Haskell?

- by Raekye

I'm probably doing this completely wrong (the unhaskell way); I'm just learning so please let me know if there's a better way to approach this. Context: I'm writing a bunch of tree structures. I want to reuse my prettyprint function for binary trees. Not all trees can use the generic Node/Branch data type though; different trees need different extra data. So to reuse the prettyprint function I thought of creating a class different trees would be instances of: class GenericBinaryTree a where is_leaf :: a -> Bool left :: a -> a node :: a -> b right :: a -> a This way they only have to implement methods to retrieve the left, right, and current node value, and prettyprint doesn't need to know about the internal structure. Then I get down to here: prettyprint_helper :: GenericBinaryTree a => a -> [String] prettyprint_helper tree | is_leaf tree = [] | otherwise = ("{" ++ (show (node tree)) ++ "}") : (prettyprint_subtree (left tree) (right tree)) where prettyprint_subtree left right = ((pad "+- " "| ") (prettyprint_helper right)) ++ ((pad "`- " " ") (prettyprint_helper left)) pad first rest = zipWith (++) (first : repeat rest) And I get the Ambiguous type variable 'a0' in the constraint: (Show a0) arising from a use of 'show' error for (show (node tree)) Here's an example of the most basic tree data type and instance definition (my other trees have other fields but they're irrelevant to the generic prettyprint function) data Tree a = Branch (Tree a) a (Tree a) | Leaf instance GenericBinaryTree (Tree a) where is_leaf Leaf = True is_leaf _ = False left (Branch left node right) = left right (Branch left node right) = right node (Branch left node right) = node I could have defined node :: a -> [String] and deal with the stringification in each instance/type of tree, but this feels neater. In terms of prettyprint, I only need a string representation, but if I add other generic binary tree functions later I may want the actual values. So how can I write this to work whether the node value is an instance of Show or not? Or what other way should I be approaching this problem? In an object oriented language I could easily check whether a class implements something, or if an object has a method. I can't use something like prettyprint :: Show a => a -> String Because it's not the tree that needs to be showable, it's the value inside the tree (returned by function node) that needs to be showable. I also tried changing node to Show b => a -> b without luck (and a bunch of other type class/preconditions/whatever/I don't even know what I'm doing anymore).

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Scripting with the Sun ZFS Storage 7000 Appliance

- by Geoff Ongley

The Sun ZFS Storage 7000 appliance has a user friendly and easy to understand graphical web based interface we call the "BUI" or "Browser User Interface".This interface is very useful for many tasks, but in some cases a script (or workflow) may be more appropriate, such as:Repetitive tasksTasks which work on (or obtain information about) a large number of shares or usersTasks which are triggered by an alert threshold (workflows)Tasks where you want a only very basic input, but a consistent output (workflows)The appliance scripting language is based on ECMAscript 3 (close to javascript). I'm not going to cover ECMAscript 3 in great depth (I'm far from an expert here), but I would like to show you some neat things you can do with the appliance, to get you started based on what I have found from my own playing around.I'm making the assumption you have some sort of programming background, and understand variables, arrays, functions to some extent - but of course if something is not clear, please let me know so I can fix it up or clarify it.Variable Declarations and ArraysVariablesECMAScript is a dynamically and weakly typed language. If you don't know what that means, google is your friend - but at a high level it means we can just declare variables with no specific type and on the fly.For example, I can declare a variable and use it straight away in the middle of my code, for example:projects=list();Which makes projects an array of values that are returned from the list(); function (which is usable in most contexts). With this kind of variable, I can do things like:projects.length (this property on array tells you how many objects are in it, good for for loops etc). Alternatively, I could say:projects=3;and now projects is just a simple number.Should we declare variables like this so loosely? In my opinion, the answer is no - I feel it is a better practice to declare variables you are going to use, before you use them - and given them an initial value. You can do so as follows:var myVariable=0;To demonstrate the ability to just randomly assign and change the type of variables, you can create a simple script at the cli as follows (bold for input):fishy10:> script("." to run)> run("cd /");("." to run)> run ("shares");("." to run)> var projects;("." to run)> projects=list();("." to run)> printf("Number of projects is: %d\n",projects.length);("." to run)> projects=152;("." to run)> printf("Value of the projects variable as an integer is now: %d\n",projects);("." to run)> .Number of projects is: 7Value of the projects variable as an integer is now: 152You can also confirm this behaviour by checking the typeof variable we are dealing with:fishy10:> script("." to run)> run("cd /");("." to run)> run ("shares");("." to run)> var projects;("." to run)> projects=list();("." to run)> printf("var projects is of type %s\n",typeof(projects));("." to run)> projects=152;("." to run)> printf("var projects is of type %s\n",typeof(projects));("." to run)> .var projects is of type objectvar projects is of type numberArraysSo you likely noticed that we have already touched on arrays, as the list(); (in the shares context) stored an array into the 'projects' variable.But what if you want to declare your own array? Easy! This is very similar to Java and other languages, we just instantiate a brand new "Array" object using the keyword new:var myArray = new Array();will create an array called "myArray".A quick example:fishy10:> script("." to run)> testArray = new Array();("." to run)> testArray[0]="This";("." to run)> testArray[1]="is";("." to run)> testArray[2]="just";("." to run)> testArray[3]="a";("." to run)> testArray[4]="test";("." to run)> for (i=0; i < testArray.length; i++)("." to run)> {("." to run)> printf("Array element %d is %s\n",i,testArray[i]);("." to run)> }("." to run)> .Array element 0 is ThisArray element 1 is isArray element 2 is justArray element 3 is aArray element 4 is testWorking With LoopsFor LoopFor loops are very similar to those you will see in C, java and several other languages. One of the key differences here is, as you were made aware earlier, we can be a bit more sloppy with our variable declarations.The general way you would likely use a for loop is as follows:for (variable; test-case; modifier for variable){}For example, you may wish to declare a variable i as 0; and a MAX_ITERATIONS variable to determine how many times this loop should repeat:var i=0;var MAX_ITERATIONS=10;And then, use this variable to be tested against some case existing (has i reached MAX_ITERATIONS? - if not, increment i using i++);for (i=0; i < MAX_ITERATIONS; i++){ // some work to do}So lets run something like this on the appliance:fishy10:> script("." to run)> var i=0;("." to run)> var MAX_ITERATIONS=10;("." to run)> for (i=0; i < MAX_ITERATIONS; i++)("." to run)> {("." to run)> printf("The number is %d\n",i);("." to run)> }("." to run)> .The number is 0The number is 1The number is 2The number is 3The number is 4The number is 5The number is 6The number is 7The number is 8The number is 9While LoopWhile loops again are very similar to other languages, we loop "while" a condition is met. For example:fishy10:> script("." to run)> var isTen=false;("." to run)> var counter=0;("." to run)> while(isTen==false)("." to run)> {("." to run)> if (counter==10) ("." to run)> { ("." to run)> isTen=true; ("." to run)> } ("." to run)> printf("Counter is %d\n",counter);("." to run)> counter++; ("." to run)> }("." to run)> printf("Loop has ended and Counter is %d\n",counter);("." to run)> .Counter is 0Counter is 1Counter is 2Counter is 3Counter is 4Counter is 5Counter is 6Counter is 7Counter is 8Counter is 9Counter is 10Loop has ended and Counter is 11So what do we notice here? Something has actually gone wrong - counter will technically be 11 once the loop completes... Why is this?Well, if we have a loop like this, where the 'while' condition that will end the loop may be set based on some other condition(s) existing (such as the counter has reached 10) - we must ensure that we terminate this iteration of the loop when the condition is met - otherwise the rest of the code will be followed which may not be desirable. In other words, like in other languages, we will only ever check the loop condition once we are ready to perform the next iteration, so any other code after we set "isTen" to be true, will still be executed as we can see it was above.We can avoid this by adding a break into our loop once we know we have set the condition - this will stop the rest of the logic being processed in this iteration (and as such, counter will not be incremented). So lets try that again:fishy10:> script("." to run)> var isTen=false;("." to run)> var counter=0;("." to run)> while(isTen==false)("." to run)> {("." to run)> if (counter==10) ("." to run)> { ("." to run)> isTen=true; ("." to run)> break;("." to run)> } ("." to run)> printf("Counter is %d\n",counter);("." to run)> counter++; ("." to run)> }("." to run)> printf("Loop has ended and Counter is %d\n", counter);("." to run)> .Counter is 0Counter is 1Counter is 2Counter is 3Counter is 4Counter is 5Counter is 6Counter is 7Counter is 8Counter is 9Loop has ended and Counter is 10Much better!Methods to Obtain and Manipulate DataGet MethodThe get method allows you to get simple properties from an object, for example a quota from a user. The syntax is fairly simple:var myVariable=get('property');An example of where you may wish to use this, is when you are getting a bunch of information about a user (such as quota information when in a shares context):var users=list();for(k=0; k < users.length; k++){ user=users[k]; run('select ' + user); var username=get('name'); var usage=get('usage'); var quota=get('quota');...Which you can then use to your advantage - to print or manipulate infomation (you could change a user's information with a set method, based on the information returned from the get method). The set method is explained next.Set MethodThe set method can be used in a simple manner, similar to get. The syntax for set is:set('property','value'); // where value is a string, if it was a number, you don't need quotesFor example, we could set the quota on a share as follows (first observing the initial value):fishy10:shares default/test-geoff> script("." to run)> var currentQuota=get('quota');("." to run)> printf("Current Quota is: %s\n",currentQuota);("." to run)> set('quota','30G');("." to run)> run('commit');("." to run)> currentQuota=get('quota');("." to run)> printf("Current Quota is: %s\n",currentQuota);("." to run)> .Current Quota is: 0Current Quota is: 32212254720This shows us using both the get and set methods as can be used in scripts, of course when only setting an individual share, the above is overkill - it would be much easier to set it manually at the cli using 'set quota=3G' and then 'commit'.List MethodThe list method can be very powerful, especially in more complex scripts which iterate over large amounts of data and manipulate it if so desired. The general way you will use list is as follows:var myVar=list();Which will make "myVar" an array, containing all the objects in the relevant context (this could be a list of users, shares, projects, etc). You can then gather or manipulate data very easily.We could list all the shares and mountpoints in a given project for example:fishy10:shares another-project> script("." to run)> var shares=list();("." to run)> for (i=0; i < shares.length; i++)("." to run)> {("." to run)> run('select ' + shares[i]);("." to run)> var mountpoint=get('mountpoint');("." to run)> printf("Share %s discovered, has mountpoint %s\n",shares[i],mountpoint);("." to run)> run('done');("." to run)> }("." to run)> .Share and-another discovered, has mountpoint /export/another-project/and-anotherShare another-share discovered, has mountpoint /export/another-project/another-shareShare bob discovered, has mountpoint /export/another-projectShare more-shares-for-all discovered, has mountpoint /export/another-project/more-shares-for-allShare yep discovered, has mountpoint /export/another-project/yepWriting More Complex and Re-Usable CodeFunctionsThe best way to be able to write more complex code is to use functions to split up repeatable or reusable sections of your code. This also makes your more complex code easier to read and understand for other programmers.We write functions as follows:function functionName(variable1,variable2,...,variableN){}For example, we could have a function that takes a project name as input, and lists shares for that project (assuming we're already in the 'project' context - context is important!):function getShares(proj){ run('select ' + proj); shares=list(); printf("Project: %s\n", proj); for(j=0; j < shares.length; j++) { printf("Discovered share: %s\n",shares[i]); } run('done'); // exit selected project}Commenting your CodeLike any other language, a large part of making it readable and understandable is to comment it. You can use the same comment style as in C and Java amongst other languages.In other words, sngle line comments use://at the beginning of the comment.Multi line comments use:/*at the beginning, and:*/ at the end.For example, here we will use both:fishy10:> script("." to run)> // This is a test comment("." to run)> printf("doing some work...\n");("." to run)> /* This is a multi-line("." to run)> comment which I will span across("." to run)> three lines in total */("." to run)> printf("doing some more work...\n");("." to run)> .doing some work...doing some more work...Your comments do not have to be on their own, they can begin (particularly with single line comments this is handy) at the end of a statement, for examplevar projects=list(); // The variable projects is an array containing all projects on the system.Try and Catch StatementsYou may be used to using try and catch statements in other languages, and they can (and should) be utilised in your code to catch expected or unexpected error conditions, that you do NOT wish to stop your code from executing (if you do not catch these errors, your script will exit!):try{ // do some work}catch(err) // Catch any error that could occur{ // do something here under the error condition}For example, you may wish to only execute some code if a context can be reached. If you can't perform certain actions under certain circumstances, that may be perfectly acceptable.For example if you want to test a condition that only makes sense when looking at a SMB/NFS share, but does not make sense when you hit an iscsi or FC LUN, you don't want to stop all processing of other shares you may not have covered yet.For example we may wish to obtain quota information on all shares for all users on a share (but this makes no sense for a LUN):function getShareQuota(shar) // Get quota for each user of this share{ run('select ' + shar); printf(" SHARE: %s\n", shar); try { run('users'); printf(" %20s %11s %11s %3s\n","Username","Usage(G)","Quota(G)","Quota(%)"); printf(" %20s %11s %11s %4s\n","--------","--------","--------","----"); users=list(); for(k=0; k < users.length; k++) { user=users[k]; getUserQuota(user); } run('done'); // exit user context } catch(err) { printf(" SKIPPING %s - This is NOT a NFS or CIFs share, not looking for users\n", shar); } run('done'); // done with this share}Running Scripts Remotely over SSHAs you have likely noticed, writing and running scripts for all but the simplest jobs directly on the appliance is not going to be a lot of fun.There's a couple of choices on what you can do here:Create scripts on a remote system and run them over sshCreate scripts, wrapping them in workflow code, so they are stored on the appliance and can be triggered under certain circumstances (like a threshold being reached)We'll cover the first one here, and then cover workflows later on (as these are for the most part just scripts with some wrapper information around them).Creating a SSH Public/Private SSH Key PairLog on to your handy Solaris box (You wouldn't be using any other OS, right? :P) and use ssh-keygen to create a pair of ssh keys. I'm storing this separate to my normal key:[geoff@lightning ~] ssh-keygen -t rsa -b 1024Generating public/private rsa key pair.Enter file in which to save the key (/export/home/geoff/.ssh/id_rsa): /export/home/geoff/.ssh/nas_key_rsaEnter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /export/home/geoff/.ssh/nas_key_rsa.Your public key has been saved in /export/home/geoff/.ssh/nas_key_rsa.pub.The key fingerprint is:7f:3d:53:f0:2a:5e:8b:2d:94:2a:55:77:66:5c:9b:14 geoff@lightningInstalling the Public Key on the ApplianceOn your Solaris host, observe the public key:[geoff@lightning ~] cat .ssh/nas_key_rsa.pub ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEAvYfK3RIaAYmMHBOvyhKM41NaSmcgUMC3igPN5gUKJQvSnYmjuWG6CBr1CkF5UcDji7v19jG3qAD5lAMFn+L0CxgRr8TNaAU+hA4/tpAGkjm+dKYSyJgEdMIURweyyfUFXoerweR8AWW5xlovGKEWZTAfvJX9Zqvh8oMQ5UJLUUc= geoff@lightningNow, copy and paste everything after "ssh-rsa" and before "user@hostname" - in this case, geoff@lightning. That is, this bit:AAAAB3NzaC1yc2EAAAABIwAAAIEAvYfK3RIaAYmMHBOvyhKM41NaSmcgUMC3igPN5gUKJQvSnYmjuWG6CBr1CkF5UcDji7v19jG3qAD5lAMFn+L0CxgRr8TNaAU+hA4/tpAGkjm+dKYSyJgEdMIURweyyfUFXoerweR8AWW5xlovGKEWZTAfvJX9Zqvh8oMQ5UJLUUc=Logon to your appliance and get into the preferences -> keys area for this user (root):[geoff@lightning ~] ssh [email protected]: Last login: Mon Dec 6 17:13:28 2010 from 192.168.0.2fishy10:> configuration usersfishy10:configuration users> select rootfishy10:configuration users root> preferences fishy10:configuration users root preferences> keysOR do it all in one hit:fishy10:> configuration users select root preferences keysNow, we create a new public key that will be accepted for this user and set the type to RSA:fishy10:configuration users root preferences keys> createfishy10:configuration users root preferences key (uncommitted)> set type=RSASet the key itself using the string copied previously (between ssh-rsa and user@host), and set the key ensuring you put double quotes around it (eg. set key="<key>"):fishy10:configuration users root preferences key (uncommitted)> set key="AAAAB3NzaC1yc2EAAAABIwAAAIEAvYfK3RIaAYmMHBOvyhKM41NaSmcgUMC3igPN5gUKJQvSnYmjuWG6CBr1CkF5UcDji7v19jG3qAD5lAMFn+L0CxgRr8TNaAU+hA4/tpAGkjm+dKYSyJgEdMIURweyyfUFXoerweR8AWW5xlovGKEWZTAfvJX9Zqvh8oMQ5UJLUUc="Now set the comment for this key (do not use spaces):fishy10:configuration users root preferences key (uncommitted)> set comment="LightningRSAKey" Commit the new key:fishy10:configuration users root preferences key (uncommitted)> commitVerify the key is there:fishy10:configuration users root preferences keys> lsKeys:NAME MODIFIED TYPE COMMENT key-000 2010-10-25 20:56:42 RSA cycloneRSAKey key-001 2010-12-6 17:44:53 RSA LightningRSAKey As you can see, we now have my new key, and a previous key I have created on this appliance.Running your Script over SSH from a Remote SystemHere I have created a basic test script, and saved it as test.ecma3:[geoff@lightning ~] cat test.ecma3 script// This is a test script, By Geoff Ongley 2010.printf("Testing script remotely over ssh\n");.Now, we can run this script remotely with our keyless login:[geoff@lightning ~] ssh -i .ssh/nas_key_rsa root@fishy10 < test.ecma3Pseudo-terminal will not be allocated because stdin is not a terminal.Testing script remotely over sshPutting it Together - An Example Completed Quota Gathering ScriptSo now we have a lot of the basics to creating a script, let us do something useful, like, find out how much every user is using, on every share on the system (you will recognise some of the code from my previous examples): script/************************************** Quick and Dirty Quota Check script ** Written By Geoff Ongley ** 25 October 2010 **************************************/function getUserQuota(usr){ run('select ' + usr); var username=get('name'); var usage=get('usage'); var quota=get('quota'); var usage_g=usage / 1073741824; // convert bytes to gigabytes var quota_g=quota / 1073741824; // as above var quota_percent=0 if (quota > 0) { quota_percent=(usage / quota)*(100/1); } printf(" %20s %8.2f %8.2f %d%%\n",username,usage_g,quota_g,quota_percent); run('done'); // done with this selected user}function getShareQuota(shar){ //printf("DEBUG: selecting share %s\n", shar); run('select ' + shar); printf(" SHARE: %s\n", shar); try { run('users'); printf(" %20s %11s %11s %3s\n","Username","Usage(G)","Quota(G)","Quota(%)"); printf(" %20s %11s %11s %4s\n","--------","--------","--------","--------"); users=list(); for(k=0; k < users.length; k++) { user=users[k]; getUserQuota(user); } run('done'); // exit user context } catch(err) { printf(" SKIPPING %s - This is NOT a NFS or CIFs share, not looking for users\n", shar); } run('done'); // done with this share}function getShares(proj){ //printf("DEBUG: selecting project %s\n",proj); run('select ' + proj); shares=list(); printf("Project: %s\n", proj); for(j=0; j < shares.length; j++) { share=shares[j]; getShareQuota(share); } run('done'); // exit selected project}function getProjects(){ run('cd /'); run('shares'); projects=list(); for (i=0; i < projects.length; i++) { var project=projects[i]; getShares(project); } run('done'); // exit context for all projects}getProjects();.Which can be run as follows, and will print information like this:[geoff@lightning ~/FISHWORKS_SCRIPTS] ssh -i ~/.ssh/nas_key_rsa root@fishy10 < get_quota_utilisation.ecma3Pseudo-terminal will not be allocated because stdin is not a terminal.Project: another-project SHARE: and-another Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- nobody 0.00 0.00 0% geoffro 0.05 0.00 0% Billy 0.10 0.00 0% root 0.00 0.00 0% testing-user 0.05 0.00 0% SHARE: another-share Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- root 0.00 0.00 0% nobody 0.00 0.00 0% geoffro 0.05 0.49 9% testing-user 0.05 0.02 249% Billy 0.10 0.29 33% SHARE: bob Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- nobody 0.00 0.00 0% root 0.00 0.00 0% SHARE: more-shares-for-all Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- Billy 0.10 0.00 0% testing-user 0.05 0.00 0% nobody 0.00 0.00 0% root 0.00 0.00 0% geoffro 0.05 0.00 0% SHARE: yep Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- root 0.00 0.00 0% nobody 0.00 0.00 0% Billy 0.10 0.01 999% testing-user 0.05 0.49 9% geoffro 0.05 0.00 0%Project: default SHARE: Test-LUN SKIPPING Test-LUN - This is NOT a NFS or CIFs share, not looking for users SHARE: test-geoff Username Usage(G) Quota(G) Quota(%) -------- -------- -------- -------- geoffro 0.05 0.00 0% root 3.18 10.00 31% uucp 0.00 0.00 0% nobody 0.59 0.49 119%^CKilled by signal 2.Creating a WorkflowWorkflows are scripts that we store on the appliance, and can have the script execute either on request (even from the BUI), or on an event such as a threshold being met.Workflow BasicsA workflow allows you to create a simple process that can be executed either via the BUI interface interactively, or by an alert being raised (for some threshold being reached, for example).The basics parameters you will have to set for your "workflow object" (notice you're creating a variable, that embodies ECMAScript) are as follows (parameters is optional):name: A name for this workflowdescription: A Description for the workflowparameters: A set of input parameters (useful when you need user input to execute the workflow)execute: The code, the script itself to execute, which will be function (parameters)With parameters, you can specify things like this (slightly modified sample taken from the System Administration Guide): ...parameters: variableParam1: { label: 'Name of Share', type: 'String' }, variableParam2 { label: 'Share Size', type: 'size' },execute: ....}; Note the commas separating the sections of name, parameters, execute, and so on. This is important!Also - there is plenty of properties you can set on the parameters for your workflow, these are described in the Sun ZFS Storage System Administration Guide.Creating a Basic Workflow from a Basic ScriptTo make a basic script into a basic workflow, you need to wrap the following around your script to create a 'workflow' object:var workflow = {name: 'Get User Quotas',description: 'Displays Quota Utilisation for each user on each share',execute: function() {// (basic script goes here, minus the "script" at the beginning, and "." at the end)}};However, it appears (at least in my experience to date) that the workflow object may only be happy with one function in the execute parameter - either that or I'm doing something wrong. As far as I can tell, after execute: you should only have a basic one function context like so:execute: function(){}To deal with this, and to give an example similar to our script earlier, I have created another simple quota check, to show the same basic functionality, but in a workflow format:var workflow = {name: 'Get User Quotas',description: 'Displays Quota Utilisation for each user on each share',execute: function () { run('cd /'); run('shares'); projects=list(); for (i=0; i < projects.length; i++) { run('select ' + projects[i]); shares=list('filesystem'); printf("Project: %s\n", projects[i]); for(j=0; j < shares.length; j++) { run('select ' +shares[j]); try { run('users'); printf(" SHARE: %s\n", shares[j]); printf(" %20s %11s %11s %3s\n","Username","Usage(G)","Quota(G)","Quota(%)"); printf(" %20s %11s %11s %4s\n","--------","--------","--------","-------"); users=list(); for(k=0; k < users.length; k++) { run('select ' + users[k]); username=get('name'); usage=get('usage'); quota=get('quota'); usage_g=usage / 1073741824; // convert bytes to gigabytes quota_g=quota / 1073741824; // as above quota_percent=0 if (quota > 0) { quota_percent=(usage / quota)*(100/1); } printf(" %20s %8.2f %8.2f %d%%\n",username,usage_g,quota_g,quota_percent); run('done'); } run('done'); // exit user context } catch(err) { // printf(" %s is a LUN, Not looking for users\n", shares[j]); } run('done'); // exit selected share context } run('done'); // exit project context } }};SummaryThe Sun ZFS Storage 7000 Appliance offers lots of different and interesting features to Sun/Oracle customers, including the world renowned Analytics. Hopefully the above will help you to think of new creative things you could be doing by taking advantage of one of the other neat features, the internal scripting engine!Some references are below to help you continue learning more, I'll update this post as I do the same! Enjoy...More information on ECMAScript 3A complete reference to ECMAScript 3 which will help you learn more of the details you may be interested in, can be found here:http://www.ecma-international.org/publications/files/ECMA-ST-ARCH/ECMA-262,%203rd%20edition,%20December%201999.pdfMore Information on Administering the Sun ZFS Storage 7000The Sun ZFS Storage 7000 System Administration guide can be a useful reference point, and can be found here:http://wikis.sun.com/download/attachments/186238602/2010_Q3_2_ADMIN.pdf

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Extending Oracle CEP with Predictive Analytics

- by vikram.shukla(at)oracle.com

Introduction: OCEP is often used as a business rules engine to execute a set of business logic rules via CQL statements, and take decisions based on the outcome of those rules. There are times where configuring rules manually is sufficient because an application needs to deal with only a small and well-defined set of static rules. However, in many situations customers don't want to pre-define such rules for two reasons. First, they are dealing with events with lots of columns and manually crafting such rules for each column or a set of columns and combinations thereof is almost impossible. Second, they are content with probabilistic outcomes and do not care about 100% precision. The former is the case when a user is dealing with data with high dimensionality, the latter when an application can live with "false" positives as they can be discarded after further inspection, say by a Human Task component in a Business Process Management software. The primary goal of this blog post is to show how this can be achieved by combining OCEP with Oracle Data Mining® and leveraging the latter's rich set of algorithms and functionality to do predictive analytics in real time on streaming events. The secondary goal of this post is also to show how OCEP can be extended to invoke any arbitrary external computation in an RDBMS from within CEP. The extensible facility is known as the JDBC cartridge. The rest of the post describes the steps required to achieve this: We use the dataset available at http://blogs.oracle.com/datamining/2010/01/fraud_and_anomaly_detection_made_simple.html to showcase the capabilities. We use it to show how transaction anomalies or fraud can be detected. Building the model: Follow the self-explanatory steps described at the above URL to build the model. It is very simple - it uses built-in Oracle Data Mining PL/SQL packages to cleanse, normalize and build the model out of the dataset. You can also use graphical Oracle Data Miner® to build the models. To summarize, it involves: Specifying which algorithms to use. In this case we use Support Vector Machines as we're trying to find anomalies in highly dimensional dataset.Build model on the data in the table for the algorithms specified. For this example, the table was populated in the scott/tiger schema with appropriate privileges. Configuring the Data Source: This is the first step in building CEP application using such an integration. Our datasource looks as follows in the server config file. It is advisable that you use the Visualizer to add it to the running server dynamically, rather than manually edit the file. <data-source> <name>DataMining</name> <data-source-params> <jndi-names> <element>DataMining</element> </jndi-names> <global-transactions-protocol>OnePhaseCommit</global-transactions-protocol> </data-source-params> <connection-pool-params> <credential-mapping-enabled></credential-mapping-enabled> <test-table-name>SQL SELECT 1 from DUAL</test-table-name> <initial-capacity>1</initial-capacity> <max-capacity>15</max-capacity> <capacity-increment>1</capacity-increment> </connection-pool-params> <driver-params> <use-xa-data-source-interface>true</use-xa-data-source-interface> <driver-name>oracle.jdbc.OracleDriver</driver-name> <url>jdbc:oracle:thin:@localhost:1522:orcl</url> <properties> <element> <value>scott</value> <name>user</name> </element> <element> <value>{Salted-3DES}AzFE5dDbO2g=</value> <name>password</name> </element> <element> <name>com.bea.core.datasource.serviceName</name> <value>oracle11.2g</value> </element> <element> <name>com.bea.core.datasource.serviceVersion</name> <value>11.2.0</value> </element> <element> <name>com.bea.core.datasource.serviceObjectClass</name> <value>java.sql.Driver</value> </element> </properties> </driver-params> </data-source> Designing the EPN: The EPN is very simple in this example. We briefly describe each of the components. The adapter ("DataMiningAdapter") reads data from a .csv file and sends it to the CQL processor downstream. The event payload here is same as that of the table in the database (refer to the attached project or do a "desc table-name" from a SQL*PLUS prompt). While this is for convenience in this example, it need not be the case. One can still omit fields in the streaming events, and need not match all columns in the table on which the model was built. Better yet, it does not even need to have the same name as columns in the table, as long as you alias them in the USING clause of the mining function. (Caveat: they still need to draw values from a similar universe or domain, otherwise it constitutes incorrect usage of the model). There are two things in the CQL processor ("DataMiningProc") that make scoring possible on streaming events. 1. User defined cartridge function Please refer to the OCEP CQL reference manual to find more details about how to define such functions. We include the function below in its entirety for illustration. <?xml version="1.0" encoding="UTF-8"?> <jdbcctxconfig:config xmlns:jdbcctxconfig="http://www.bea.com/ns/wlevs/config/application" xmlns:jc="http://www.oracle.com/ns/ocep/config/jdbc"> <jc:jdbc-ctx> <name>Oracle11gR2</name> <data-source>DataMining</data-source> <function name="prediction2"> <param name="CQLMONTH" type="char"/> <param name="WEEKOFMONTH" type="int"/> <param name="DAYOFWEEK" type="char" /> <param name="MAKE" type="char" /> <param name="ACCIDENTAREA" type="char" /> <param name="DAYOFWEEKCLAIMED" type="char" /> <param name="MONTHCLAIMED" type="char" /> <param name="WEEKOFMONTHCLAIMED" type="int" /> <param name="SEX" type="char" /> <param name="MARITALSTATUS" type="char" /> <param name="AGE" type="int" /> <param name="FAULT" type="char" /> <param name="POLICYTYPE" type="char" /> <param name="VEHICLECATEGORY" type="char" /> <param name="VEHICLEPRICE" type="char" /> <param name="FRAUDFOUND" type="int" /> <param name="POLICYNUMBER" type="int" /> <param name="REPNUMBER" type="int" /> <param name="DEDUCTIBLE" type="int" /> <param name="DRIVERRATING" type="int" /> <param name="DAYSPOLICYACCIDENT" type="char" /> <param name="DAYSPOLICYCLAIM" type="char" /> <param name="PASTNUMOFCLAIMS" type="char" /> <param name="AGEOFVEHICLES" type="char" /> <param name="AGEOFPOLICYHOLDER" type="char" /> <param name="POLICEREPORTFILED" type="char" /> <param name="WITNESSPRESNT" type="char" /> <param name="AGENTTYPE" type="char" /> <param name="NUMOFSUPP" type="char" /> <param name="ADDRCHGCLAIM" type="char" /> <param name="NUMOFCARS" type="char" /> <param name="CQLYEAR" type="int" /> <param name="BASEPOLICY" type="char" /> <return-component-type>char</return-component-type> <sql><![CDATA[ SELECT to_char(PREDICTION_PROBABILITY(CLAIMSMODEL, '0' USING *)) AS probability FROM (SELECT :CQLMONTH AS MONTH, :WEEKOFMONTH AS WEEKOFMONTH, :DAYOFWEEK AS DAYOFWEEK, :MAKE AS MAKE, :ACCIDENTAREA AS ACCIDENTAREA, :DAYOFWEEKCLAIMED AS DAYOFWEEKCLAIMED, :MONTHCLAIMED AS MONTHCLAIMED, :WEEKOFMONTHCLAIMED, :SEX AS SEX, :MARITALSTATUS AS MARITALSTATUS, :AGE AS AGE, :FAULT AS FAULT, :POLICYTYPE AS POLICYTYPE, :VEHICLECATEGORY AS VEHICLECATEGORY, :VEHICLEPRICE AS VEHICLEPRICE, :FRAUDFOUND AS FRAUDFOUND, :POLICYNUMBER AS POLICYNUMBER, :REPNUMBER AS REPNUMBER, :DEDUCTIBLE AS DEDUCTIBLE, :DRIVERRATING AS DRIVERRATING, :DAYSPOLICYACCIDENT AS DAYSPOLICYACCIDENT, :DAYSPOLICYCLAIM AS DAYSPOLICYCLAIM, :PASTNUMOFCLAIMS AS PASTNUMOFCLAIMS, :AGEOFVEHICLES AS AGEOFVEHICLES, :AGEOFPOLICYHOLDER AS AGEOFPOLICYHOLDER, :POLICEREPORTFILED AS POLICEREPORTFILED, :WITNESSPRESNT AS WITNESSPRESENT, :AGENTTYPE AS AGENTTYPE, :NUMOFSUPP AS NUMOFSUPP, :ADDRCHGCLAIM AS ADDRCHGCLAIM, :NUMOFCARS AS NUMOFCARS, :CQLYEAR AS YEAR, :BASEPOLICY AS BASEPOLICY FROM dual) ]]> </sql> </function> </jc:jdbc-ctx> </jdbcctxconfig:config> 2. Invoking the function for each event. Once this function is defined, you can invoke it from CQL as follows: <?xml version="1.0" encoding="UTF-8"?> <wlevs:config xmlns:wlevs="http://www.bea.com/ns/wlevs/config/application"> <processor> <name>DataMiningProc</name> <rules> <query id="q1"><![CDATA[ ISTREAM(SELECT S.CQLMONTH, S.WEEKOFMONTH, S.DAYOFWEEK, S.MAKE, : S.BASEPOLICY, C.F AS probability FROM StreamDataChannel [NOW] AS S, TABLE(prediction2@Oracle11gR2(S.CQLMONTH, S.WEEKOFMONTH, S.DAYOFWEEK, S.MAKE, ..., S.BASEPOLICY) AS F of char) AS C) ]]></query> </rules> </processor> </wlevs:config> Finally, the last stage in the EPN prints out the probability of the event being an anomaly. One can also define a threshold in CQL to filter out events that are normal, i.e., below a certain mark as defined by the analyst or designer. Sample Runs: Now let's see how this behaves when events are streamed through CEP. We use only two events for brevity, one normal and other one not. This is one of the "normal" looking events and the probability of it being anomalous is less than 60%. Event is: eventType=DataMiningOutEvent object=q1 time=2904821976256 S.CQLMONTH=Dec, S.WEEKOFMONTH=5, S.DAYOFWEEK=Wednesday, S.MAKE=Honda, S.ACCIDENTAREA=Urban, S.DAYOFWEEKCLAIMED=Tuesday, S.MONTHCLAIMED=Jan, S.WEEKOFMONTHCLAIMED=1, S.SEX=Female, S.MARITALSTATUS=Single, S.AGE=21, S.FAULT=Policy Holder, S.POLICYTYPE=Sport - Liability, S.VEHICLECATEGORY=Sport, S.VEHICLEPRICE=more than 69000, S.FRAUDFOUND=0, S.POLICYNUMBER=1, S.REPNUMBER=12, S.DEDUCTIBLE=300, S.DRIVERRATING=1, S.DAYSPOLICYACCIDENT=more than 30, S.DAYSPOLICYCLAIM=more than 30, S.PASTNUMOFCLAIMS=none, S.AGEOFVEHICLES=3 years, S.AGEOFPOLICYHOLDER=26 to 30, S.POLICEREPORTFILED=No, S.WITNESSPRESENT=No, S.AGENTTYPE=External, S.NUMOFSUPP=none, S.ADDRCHGCLAIM=1 year, S.NUMOFCARS=3 to 4, S.CQLYEAR=1994, S.BASEPOLICY=Liability, probability=.58931702982118561 isTotalOrderGuarantee=true\nAnamoly probability: .58931702982118561 However, the following event is scored as an anomaly with a very high probability of 89%. So there is likely to be something wrong with it. A close look reveals that the value of "deductible" field (10000) is not "normal". What exactly constitutes normal here?. If you run the query on the database to find ALL distinct values for the "deductible" field, it returns the following set: {300, 400, 500, 700} Event is: eventType=DataMiningOutEvent object=q1 time=2598483773496 S.CQLMONTH=Dec, S.WEEKOFMONTH=5, S.DAYOFWEEK=Wednesday, S.MAKE=Honda, S.ACCIDENTAREA=Urban, S.DAYOFWEEKCLAIMED=Tuesday, S.MONTHCLAIMED=Jan, S.WEEKOFMONTHCLAIMED=1, S.SEX=Female, S.MARITALSTATUS=Single, S.AGE=21, S.FAULT=Policy Holder, S.POLICYTYPE=Sport - Liability, S.VEHICLECATEGORY=Sport, S.VEHICLEPRICE=more than 69000, S.FRAUDFOUND=0, S.POLICYNUMBER=1, S.REPNUMBER=12, S.DEDUCTIBLE=10000, S.DRIVERRATING=1, S.DAYSPOLICYACCIDENT=more than 30, S.DAYSPOLICYCLAIM=more than 30, S.PASTNUMOFCLAIMS=none, S.AGEOFVEHICLES=3 years, S.AGEOFPOLICYHOLDER=26 to 30, S.POLICEREPORTFILED=No, S.WITNESSPRESENT=No, S.AGENTTYPE=External, S.NUMOFSUPP=none, S.ADDRCHGCLAIM=1 year, S.NUMOFCARS=3 to 4, S.CQLYEAR=1994, S.BASEPOLICY=Liability, probability=.89171554529576691 isTotalOrderGuarantee=true\nAnamoly probability: .89171554529576691 Conclusion: By way of this example, we show: real-time scoring of events as they flow through CEP leveraging Oracle Data Mining.how CEP applications can invoke complex arbitrary external computations (function shipping) in an RDBMS.

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