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  • How should I properly format this code?

    - by ct2k7
    Hi, I've a small issue here. I am using an if statement with UIAlertView and I have two situations, both result in UIAlertViews. However, in one situation, I want to dismiss just the UIAlertView, the other, I want the UIAlertView to be dismissed and view to return to root view. This code describes is: if([serverOutput isEqualToString:@"login.true"]){ [Alert dismissWithClickedButtonIndex:0 animated:YES]; [UIApplication sharedApplication].networkActivityIndicatorVisible = NO; UIAlertView *success = [[UIAlertView alloc] initWithTitle:@"Success" message:@"The transaction was a success!" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil]; [success show]; [success release]; } else { UIAlertView *failure = [[UIAlertView alloc] initWithTitle:@"Failure" message:@"The transaction failed. Contact sales operator!" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil]; [failure show]; [failure release]; } } -(void)alertView: (UIAlertView *)success clickedButtonAtIndex: (NSInteger)buttonIndex{ switch(buttonIndex) { case 0: { [self.navigationController popToRootViewControllerAnimated:YES]; } } } So, in both cases, they follow the above action, but obviously, that's not what I want. Any ideas on what I do here?

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  • Validations for a has_many/belongs_to relationship

    - by Craig Walker
    I have a Recipe model which has_many Ingredients (which in turn belongs_to Recipe). I want Ingredient to be existent dependent on Recipe; an Ingredient should never exist without a Recipe. I'm trying to enforce the presence of a valid Recipe ID in the Ingredient. I've been doing this with a validates :recipe, :presence => true (Rails 3) statement in Ingredient. This works fine if I save the Recipe before adding an Ingredient to it's ingredients collection. However, if I don't have explicit control over the saving (such as when I'm creating a Recipe and its Ingredients from a nested form) then I get an error: Ingredients recipe can't be blank I can get around this simply by dropping the presence validation on Ingredient.recipe. However, I don't particularly like this, as it means I'm working without a safety net. What is the best way to enforce existence-dependence in Rails? Things I'm considering (please comment on the wisdom of each): Adding a not-null constraint on the ingredients.recipe_id database column, and letting the database do the checking for me. A custom validation that somehow checks whether the Ingredient is in an unsaved recipe's ingredient collection (and thus can't have a recipe_id but is still considered valid).

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  • Getting the first of a GROUP BY clause in SQL

    - by Michael Bleigh
    I'm trying to implement single-column regionalization for a Rails application and I'm running into some major headaches with a complex SQL need. For this system, a region can be represented by a country code (e.g. us) a continent code that is uppercase (e.g. NA) or it can be NULL indicating the "default" information. I need to group these items by some relevant information such as a foreign key (we'll call it external_id). Given a country and its continent, I need to be able to select only the most specific region available. So if records exist with the country code, I select them. If, not I want a records with the continent code. If not that, I want records with a NULL code so I can receive the default values. So far I've figured that I may be able to use a generated CASE statement to get an arbitrary sort order. Something like this: SELECT *, CASE region WHEN 'us' THEN 1 WHEN 'NA' THEN 2 ELSE 3 END AS region_sort FROM my_table WHERE region IN ('us','NA') OR region IS NULL GROUP BY external_id ORDER BY region_sort The problem is that without an aggregate function the actual data returned by the GROUP BY for a given row seems to be untameable. How can I massage this query to make it return only the first record of the region_sort ordered groups?

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  • Fatal error with Custom Magento Module on one server but not the other

    - by Jack
    Hi, I am creating my own custom module in Magento and during testing on a Litespeed server (PHP v5.2.14) I am getting a Fatal Error: Call to a member function batch() on a non-object in ../../../BatchController.php on line 25 that was not appearing during testing on another linux server and a wamp server (PHP v5.2.11). This one has stumped me. I am guessing it has something to do with the server configuration rather than the code itself. But i am just guessing. I was hoping someone here could tell me. The only real major difference I could see, aside from the php versions and environment, is that the server that the error is on is using the Suhosin Patch. But would that be something that could cause this? The line in question is Mage::getModel('mymodule/mymodel')->batch(); which is enclosed in an IF statement. batch() is a public function located in my model file. If you need more code let me know. Thanks!

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  • CUDA - multiple kernels to compute a single value

    - by Roger
    Hey, I'm trying to write a kernel to essentially do the following in C float sum = 0.0; for(int i = 0; i < N; i++){ sum += valueArray[i]*valueArray[i]; } sum += sum / N; At the moment I have this inside my kernel, but it is not giving correct values. int i0 = blockIdx.x * blockDim.x + threadIdx.x; for(int i=i0; i<N; i += blockDim.x*gridDim.x){ *d_sum += d_valueArray[i]*d_valueArray[i]; } *d_sum= __fdividef(*d_sum, N); The code used to call the kernel is kernelName<<<64,128>>>(N, d_valueArray, d_sum); cudaMemcpy(&sum, d_sum, sizeof(float) , cudaMemcpyDeviceToHost); I think that each kernel is calculating a partial sum, but the final divide statement is not taking into account the accumulated value from each of the threads. Every kernel is producing it's own final value for d_sum? Does anyone know how could I go about doing this in an efficient way? Maybe using shared memory between threads? I'm very new to GPU programming. Cheers

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  • temporary tables within stored procedures on slave servers with readonly set

    - by lau
    Hi, We have set up a replication scheme master/slave and we've had problems lately because some users wrote directly on the slave instead of the master, making the whole setup inconsistent. To prevent these problems from happening again, we've decided to remove the insert, delete, update, etc... rights from the users accessing the slave. Problems is that some stored procedure (for reading) require temporary tables. I read that changing the global variable read_only to true would do what I want and allow the stored procedures to work correctly ( http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html#sysvar_read_only ) but I keep getting the error : The MySQL server is running with the --read-only option so it cannot execute this statement (1290) The stored procedure that I used (for testing purpose) is this one : DELIMITER $$ DROP PROCEDURE IF EXISTS test_readonly $$ CREATE DEFINER=dbuser@% PROCEDURE test_readonly() BEGIN CREATE TEMPORARY TABLE IF NOT EXISTS temp ( BT_INDEX int(11), BT_DESC VARCHAR(10) ); INSERT INTO temp (BT_INDEX, BT_DESC) VALUES (222,'walou'), (111,'bidouille'); DROP TABLE temp; END $$ DELIMITER ; The create temporary table and the drop table work fine with the readonly flag - if I comment the INSERT line, it runs fine- but whenever I want to insert or delete from that temporary table, I get the error message. I use Mysql 5.1.29-rc. My default storage engine is InnoDB. Thanks in advance, this problem is really driving me crazy.

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  • Providing custom database functionality to custom asp.net membership provider

    - by IrfanRaza
    Hello friends, I am creating custom membership provider for my asp.net application. I have also created a separate class "DBConnect" that provides database functionality such as Executing SQL statement, Executing SPs, Executing SPs or Query and returning SqlDataReader and so on... I have created instance of DBConnect class within Session_Start of Global.asax and stored to a session. Later using a static class I am providing the database functionality throughout the application using the same single session. In short I am providing a single point for all database operations from any asp.net page. I know that i can write my own code to connect/disconnect database and execute SPs within from the methods i need to override. Please look at the code below - public class SGI_MembershipProvider : MembershipProvider { ...... public override bool ChangePassword(string username, string oldPassword, string newPassword) { if (!ValidateUser(username, oldPassword)) return false; ValidatePasswordEventArgs args = new ValidatePasswordEventArgs(username, newPassword, true); OnValidatingPassword(args); if (args.Cancel) { if (args.FailureInformation != null) { throw args.FailureInformation; } else { throw new Exception("Change password canceled due to new password validation failure."); } } ..... //Database connectivity and code execution to change password. } .... } MY PROBLEM - Now what i need is to execute the database part within all these overriden methods from the same database point as described on the top. That is i have to pass the instance of DBConnect existing in the session to this class, so that i can access the methods. Could anyone provide solution on this. There might be some better techniques i am not aware of that. The approach i am using might be wrong. Your suggessions are always welcome. Thanks for sharing your valuable time.

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  • How can I have 2 ADO access methods use the same Transaction?

    - by KevinDeus
    I'm writing a test to see if my LINQ to Entity statement works.. I'll be using this for others if I can get this concept going.. my intention here is to INSERT a record with ADO, then verify it can be queried with LINQ, and then ROLLBACK the whole thing at the end. I'm using ADO to insert because I don't want to use the object or the entity model that I am testing. I figure that a plain ADO INSERT should do fine. problem is.. they both use different types of connections. is it possible to have these 2 different data access methods use the same TRANSACTION so I can roll it back?? _conn = new SqlConnection(_connectionString); _conn.Open(); _trans = _conn.BeginTransaction(); var x = new SqlCommand("INSERT INTO Table1(ID, LastName, FirstName, DateOfBirth) values('127', 'test2', 'user', '2-12-1939');", _conn); x.ExecuteNonQuery(); //So far, so good. Adding a record to the table. //at this point, we need to do **_trans.Commit()** here because our Entity code can't use the same connection. Then I have to manually delete in the TestHarness.TearDown.. I'd like to eliminate this step //(this code is in another object, I'll include it for brevity. Imagine that I passed the connection in) //check to see if it is there using (var ctx = new XEntities(_conn)) //can't do this.. _conn is not an EntityConnection! { var retVal = (from m in ctx.Table1 where m.first_name == "test2" where m.last_name == "user" where m.Date_of_Birth == "2-12-1939" where m.ID == 127 select m).FirstOrDefault(); return (retVal != null); } //Do test.. Assert.BlahBlah(); _trans.Rollback();

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  • Drag Drop copy file

    - by Graham Warrender
    I've perhaps done something marginally stupid, but can't see what it is!! string pegasusKey = @"HKEY_LOCAL_MACHINE\SOFTWARE\Pegasus\"; string opera2ServerPath = @"Server VFP\"; string opera3ServerPath = @"O3 Client VFP\"; string opera2InstallationPath = null; string opera3InstallationPath = null; //Gets the opera Installtion paths and reads to the string opera*InstallationPath opera2InstallationPath = (string)Registry.GetValue(pegasusKey + opera2ServerPath + "System", "PathToServerDynamic", null); opera3InstallationPath = (string)Registry.GetValue(pegasusKey + opera3ServerPath + "System", "PathToServerDynamic", null); string Filesource = null; string[] FileList = (string[])e.Data.GetData(DataFormats.FileDrop, false); foreach (string File in FileList) Filesource = File; label.Text = Filesource; if (System.IO.Directory.Exists(opera3InstallationPath)) { System.IO.File.Copy(Filesource, opera3InstallationPath); MessageBox.Show("File Copied from" + Filesource + "\n to" + opera3InstallationPath); } else { MessageBox.Show("Directory Doesn't Exist"); } The user drags the file onto the window, I then get the installation path of an application which is then used as the destination for the source file.. When the application is runs, it throws the error directory not found. But surely if the directory doesn't exists is should step into the else statement? a simple application that is becoming a headache!!

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  • Generated sql from LINQ to SQL

    - by Muhammad Kashif Nadeem
    Following code ProductPricesDataContext db = new ProductPricesDataContext(); var products = from p in db.Products where p.ProductFields.Count > 3 select new { ProductIDD = p.ProductId, ProductName = p.ProductName.Contains("hotel"), NumbeOfProd = p.ProductFields.Count, totalFields = p.ProductFields.Sum(o => o.FieldId + o.FieldId) }; Generated follwing sql SELECT [t0].[ProductId] AS [ProductIDD], (CASE WHEN [t0].[ProductName] LIKE '%hotel%' THEN 1 WHEN NOT ([t0].[ProductName] LIKE '%hotel%') THEN 0 ELSE NULL END) AS [ProductName], ( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t2] WHERE [t2].[ProductId] = [t0].[ProductId] ) AS [NumbeOfProd], ( SELECT SUM([t3].[FieldId] + [t3].[FieldId]) FROM [dbo].[ProductField] AS [t3] WHERE [t3].[ProductId] = [t0].[ProductId]) AS [totalFields] FROM [dbo].[Product] AS [t0] WHERE (( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t1] WHERE [t1].[ProductId] = [t0].[ProductId] )) > 3 Why is this CASE statement for ProductName and because of this instead of ProductName i am just getting 0 in my result set. It should generate sql like following, (where ProductName like '%hotel%' SELECT [t0].[ProductId] AS [ProductIDD], [ProductName], ( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t2] WHERE [t2].[ProductId] = [t0].[ProductId] ) AS [NumbeOfProd], ( SELECT SUM([t3].[FieldId] + [t3].[FieldId]) FROM [dbo].[ProductField] AS [t3] WHERE [t3].[ProductId] = [t0].[ProductId]) AS [totalFields] FROM [dbo].[Product] AS [t0] WHERE (( SELECT COUNT(*) FROM [dbo].[ProductField] AS [t1] WHERE [t1].[ProductId] = [t0].[ProductId] )) > 3 AND t0.ProductName like '%hotel%' Thanks.

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  • doubt in javascript name validation

    - by raja
    Hi: I am using the below validation for textbox which accepts only alphabets and maximum of 50 characters. I am passing the object directly in the parameter. The below case by giving the field name i.e "my_text" directly is working is working fine. But if i pass it in variable, that time it is not working(commented the if statement). Please help me. My requirement is each time when we enter the charater, the hardcode field name should not be used in the validation. <html><head> <script language=JavaScript> function check_length(my_form,fieldName) { alert(fieldName); // if (my_form.fieldName.value.length >= maxLen) { if (my_form.my_text.value.length >= maxLen) { var msg = "You have reached your maximum limit of characters allowed"; alert(msg); my_form.my_text.value = my_form.my_text.value.substring(0, maxLen); } else{ var keyCode = window.event.keyCode; if ((keyCode < 65 || keyCode > 90) && (keyCode < 97 || keyCode > 123) && keyCode != 32) { window.event.returnValue = false; alert("Enter only Alphabets"); } my_form.text_num.value = maxLen - my_form.my_text.value.length;} } </script> </head> <body> <form name=my_form method=post> <input type="text" onKeyPress=check_length(this.form,this.name); name=my_text rows=4 cols=30> <br> <input size=1 value=50 name=text_num> Characters Left </form> </body> </html>

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  • Somewhat lost with jquery + php + json

    - by Luis Armando
    I am starting to use the jquery $.ajax() but I can't get back what I want to...I send this: $(function(){ $.ajax({ url: "graph_data.php", type: "POST", data: "casi=56&nada=48&nuevo=98&perfecto=100&vales=50&apenas=70&yeah=60", dataType: "json", error: function (xhr, desc, exceptionobj) { document.writeln("El error de XMLHTTPRequest dice: " + xhr.responseText); }, success: function (json) { if (json.error) { alert(json.error); return; } var output = ""; for (p in json) { output += p + " : " + json[p] + "\n"; } document.writeln("Results: \n\n" + output); } }); }); and my php is: <?php $data = $_POST['data']; function array2json($data){ $json = $data; return json_encode($json); } ?> and when I execute this I come out with: Results: just like that I used to have in the php a echo array2json statement but it just gave back gibberish...I really don't know what am I doing wrong and I've googled for about 3 hours just getting basically the same stuff. Also I don't know how to pass parameters to the "data:" in the $.ajax function in another way like getting info from the web page, can anyone please help me? Edit I did what you suggested and it prints the data now thank you very much =) however, I was wondering, how can I send the data to the "data:" part in jQuery so it takes it from let's say user input, also I was checking the php documentation and it says I'm allowed to write something like: json_encode($a,JSON_HEX_TAG|JSON_HEX_APOS|JSON_HEX_QUOT|JSON_HEX_AMP) however, if I do that I get an error saying that json_encode accepts 1 parameter and I'm giving 2...any idea why? I'm using php 5.2

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  • How SQLite on Android handles long strings?

    - by Levara
    I'm wondering how Android's implementation of SQLite handles long Strings. Reading from online documentation on sqlite, it said that strings in sqlite are limited to 1 million characters. My strings are definitely smaller. I'm creating a simple RSS application, and after parsing a html document, and extracting text, I'm having problem saving it to a database. I have 2 tables in database, feeds and articles. RSS feeds are correctly saved and retrieved from feeds table, but when saving to the articles table, logcat is saying that it cannot save extracted text to it's column. I don't know if other columns are making problems too, no mention of them in logcat. I'm wondering, since text is from an article on web, are signs like (",',;) creating problems? Is Android automaticaly escaping them, or I have to do that. I'm using a technique for inserting similar to one in notepad tutorial: public long insertArticle(long feedid, String title, String link, String description, String h1,tring h2, String h3, String p, String image, long date) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_FEEDID, feedid); initialValues.put(KEY_TITLE, title); initialValues.put(KEY_LINK, link); initialValues.put(KEY_DESCRIPTION, description ); initialValues.put(KEY_H1, h1 ); initialValues.put(KEY_H2, h2); initialValues.put(KEY_H3, h3); initialValues.put(KEY_P, p); initialValues.put(KEY_IMAGE, image); initialValues.put(KEY_DATE, date); return mDb.insert(DATABASE_TABLE_ARTICLES,null, initialValues); } Column P is for extracted text, h1, h2 and h3 are for headers from a page. Logcat reports only column p to be the problem. The table is created with following statement: private static final String DATABASE_CREATE_ARTICLES = "create table articles( _id integer primary key autoincrement, feedid integer, title text, link text not null, description text," + "h1 text, h2 text, h3 text, p text, image text, date integer);";

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  • Finding duplicates in a list using recursion?

    - by user1760892
    I'm suppose to find if there is duplicates in a list and return true or false using recursion only (no loops). So if ArrayList of char is used, [a,b,c,d,e] should return false. [a,a,b,c,d] or [a,b,b,c,c,d] should return true. I've tried and tested different ways and it worked for some cases but not all. I changed my code around and this is what I have now. (Has problem at the last if statement) Can anyone give me some hints? Thanks. public static <T> boolean duplicate(List<T> list) throws NullPointerException { return duplicateHelper(list, list.get(0)); } public static <T> boolean duplicateHelper(List<T> list, T t){ if (list == null) throw new NullPointerException(); if(list.isEmpty()) return false; if(list.size() > 1){ if(t.equals(list.get(1))) return true; } if(list.size() == 1) return false; if(!duplicateHelper(list.subList(1,list.size()), t)){ return duplicate(list.subList(1,list.size())); } return false; }

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  • ODP.NET Procedure Compilation

    - by Bobcat1506
    When I try to execute a create procedure using ODP.NET I get back ORA-24344: success with compilation error. However, when I run the same statement in SQL Developer it compiles successfully. Does anyone know what I need to change to get my procedure to compile? Is it a character set issue? I am using Oracle 10g Express, .NET 3.5 SP 1, and ODP.NET 2.111.7.20 (version from Oracle.DataAccess.dll) [TestMethod] public void OdpNet_CreateProcedure() { ConnectionStringSettings settings = ConfigurationManager.ConnectionStrings["ODP.NET"]; using (var con = new OracleConnection(settings.ConnectionString)) { con.InfoMessage += new OracleInfoMessageEventHandler(con_InfoMessage); con.Open(); var cmd = new OracleCommand(); cmd.Connection = con; cmd.CommandText = @" CREATE OR REPLACE PROCEDURE TABLE1_GET ( P_CURSOR OUT SYS_REFCURSOR ) IS BEGIN OPEN P_CURSOR FOR SELECT * FROM TABLE1; END;"; cmd.ExecuteNonQuery(); // ORA-24344: success with compilation error cmd.CommandText = @"ALTER PROCEDURE TABLE1_GET COMPILE"; cmd.ExecuteNonQuery(); // ORA-24344: success with compilation error } } void con_InfoMessage(object sender, OracleInfoMessageEventArgs eventArgs) { System.Diagnostics.Debug.WriteLine(eventArgs.Message); }

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  • MySQLPython is ignoring my my.cnf file. Where does it get its information?

    - by ?????
    When I try to use MySQLPython (via SQLAlchemy) I get the error File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/MySQL_python-1.2.3c1-py2.6-macosx-10.6-x86_64.egg/MySQLdb/connections.py", line 188, in __init__ super(Connection, self).__init__(*args, **kwargs2) sqlalchemy.exc.OperationalError: (OperationalError) (2002, "Can't connect to local MySQL server through socket '/opt/local/var/run/mysql5/mysqld.sock' (2)") None None but no other mysql client on my machine sees it fine! My my.cnf file states: [client] port = 3306 socket = /tmp/mysql/mysql.sock [safe_mysqld] socket = /tmp/mysql/mysql.sock [mysqld_safe] socket = /tmp/mysql/mysql.sock [mysqld] socket = /tmp/mysql/mysql.sock port = 3306 and the mysql.sock file is, indeed, located in /tmp/mysql I verified that ~/.my.cnf and /var/lib/mysql/my.cnf aren't overriding it. The mysql5 client program, etc, has no trouble connecting and neither does a groovy/grails installation on the same machine using jdbc/mysql connection thrilllap-2:~ swirsky$ mysql5 Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 6 Server version: 5.1.47 Source distribution Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved. This software comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to modify and redistribute it under the GPL v2 license Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | test | +--------------------+ 2 rows in set (0.00 sec) mysql> Why can't MySQLdb for python figure this out? Where would it look if not the my.cnf files?

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  • How to parallelize this groovy code?

    - by lucas
    I'm trying to write a reusable component in Groovy to easily shoot off emails from some of our Java applications. I would like to pass it a List, where Email is just a POJO(POGO?) with some email info. I'd like it to be multithreaded, at least running all the email logic in a second thread, or make one thread per email. I am really foggy on multithreading in Java so that probably doesn't help! I've attempted a few different ways, but here is what I have right now: void sendEmails(List<Email> emails) { def threads = [] def sendEm = emails.each{ email -> def th = new Thread({ Random rand = new Random() def wait = (long)(rand.nextDouble() * 1000) println "in closure" this.sleep wait sendEmail(email) }) println "putting thread in list" threads << th } threads.each { it.run() } threads.each { it.join() } } I was hoping the sleep would randomly slow some threads down so the console output wouldn't be sequential. Instead, I see this: putting thread in list putting thread in list putting thread in list putting thread in list putting thread in list putting thread in list putting thread in list putting thread in list putting thread in list putting thread in list in closure sending email1 in closure sending email2 in closure sending email3 in closure sending email4 in closure sending email5 in closure sending email6 in closure sending email7 in closure sending email8 in closure sending email9 in closure sending email10 sendEmail basically does what you'd expect, including the println statement, and the client that calls this follows, void doSomething() { Mailman emailer = MailmanFactory.getExchangeEmailer() def to = ["one","two"] def from = "noreply" def li = [] def email (1..10).each { email = new Email(to,null,from,"email"+it,"hello") li << email } emailer.sendEmails li }

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  • Generics vs inheritance (when no collection classes are involved)

    - by Ram
    This is an extension of this questionand probably might even be a duplicate of some other question(If so, please forgive me). I see from MSDN that generics are usually used with collections The most common use for generic classes is with collections like linked lists, hash tables, stacks, queues, trees and so on where operations such as adding and removing items from the collection are performed in much the same way regardless of the type of data being stored. The examples I have seen also validate the above statement. Can someone give a valid use of generics in a real-life scenario which does not involve any collections ? Pedantically, I was thinking about making an example which does not involve collections public class Animal<T> { public void Speak() { Console.WriteLine("I am an Animal and my type is " + typeof(T).ToString()); } public void Eat() { //Eat food } } public class Dog { public void WhoAmI() { Console.WriteLine(this.GetType().ToString()); } } and "An Animal of type Dog" will be Animal<Dog> magic = new Animal<Dog>(); It is entirely possible to have Dog getting inherited from Animal (Assuming a non-generic version of Animal)Dog:Animal Therefore Dog is an Animal Another example I was thinking was a BankAccount. It can be BankAccount<Checking>,BankAccount<Savings>. This can very well be Checking:BankAccount and Savings:BankAccount. Are there any best practices to determine if we should go with generics or with inheritance ?

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  • SQL Server race condition issue with range lock

    - by Freek
    I'm implementing a queue in SQL Server (please no discussions about this) and am running into a race condition issue. The T-SQL of interest is the following: set transaction isolation level serializable begin tran declare @RecordId int declare @CurrentTS datetime2 set @CurrentTS=CURRENT_TIMESTAMP select top 1 @RecordId=Id from QueuedImportJobs with (updlock) where Status=@Status and (LeaseTimeout is null or @CurrentTS>LeaseTimeout) order by Id asc if @@ROWCOUNT> 0 begin update QueuedImportJobs set LeaseTimeout = DATEADD(mi,5,@CurrentTS), LeaseTicket=newid() where Id=@RecordId select * from QueuedImportJobs where Id = @RecordId end commit tran RecordId is the PK and there is also an index on Status,LeaseTimeout. What I'm basically doing is select a record of which the lease happens to be expired, while simultaneously updating the lease time with 5 minutes and setting a new lease ticket. So the problem is that I'm getting deadlocks when I run this code in parallel using a couple of threads. I've debugged it up to the point where I found out that the update statement sometimes gets executing twice for the same record. Now, I was under the impression that the with (updlock) should prevent this (it also happens with xlock btw, not with tablockx). So it actually look like there is a RangeS-U and a RangeX-X lock on the same range of records, which ought to be impossible. So what am I missing? I'm thinking it might have something to do with the top 1 clause or that SQL Server does not know that where Id=@RecordId is actually in the locked range? Deadlock graph: Table schema (simplified):

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  • JavaScript Module Pattern - What about using "return this"?

    - by Rob
    After doing some reading about the Module Pattern, I've seen a few ways of returning the properties which you want to be public. One of the most common ways is to declare your public properties and methods right inside of the "return" statement, apart from your private properties and methods. A similar way (the "Revealing" pattern) is to provide simply references to the properties and methods which you want to be public. Lastly, a third technique I saw was to create a new object inside your module function, to which you assign your new properties before returning said object. This was an interesting idea, but requires the creation of a new object. So I was thinking, why not just use "this.propertyName" to assign your public properties and methods, and finally use "return this" at the end? This way seems much simpler to me, as you can create private properties and methods with the usual "var" or "function" syntax, or use the "this.propertyName" syntax to declare your public methods. Here's the method I'm suggesting: (function() { var privateMethod = function () { alert('This is a private method.'); } this.publicMethod = function () { alert('This is a public method.'); } return this; })(); Are there any pros/cons to using the method above? What about the others?

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  • Elegantly determine if more than one boolean is "true"

    - by Ola Tuvesson
    I have a set of five boolean values. If more than one of these are true I want to excecute a particular function. What is the most elegant way you can think of that would allow me to check this condition in a single if() statement? Target language is C# but I'm interested in solutions in other languages as well (as long as we're not talking about specific built-in functions). One interesting option is to store the booleans in a byte, do a right shift and compare with the original byte. Something like if(myByte && (myByte 1)) But this would require converting the separate booleans to a byte (via a bitArray?) and that seems a bit (pun intended) clumsy... [edit]Sorry, that should have been if(myByte & (myByte - 1)) [/edit] Note: This is of course very close to the classical "population count", "sideways addition" or "Hamming weight" programming problem - but not quite the same. I don't need to know how many of the bits are set, only if it is more than one. My hope is that there is a much simpler way to accomplish this.

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  • Multiple case or switch commands in php?

    - by kitenski
    Good Afternoon, I am trying to assign some variables to a listing which has a main category and a subcategory. This works fine for most of the variables, however in each sub category there are some fields which are other. ie Main Category 1 has sub category database, development and other Main Category 2 has sub category email, internet and other Main Category 3 has sub category graphics and other. So my first case statement is as follows which works fine. switch ($main_cat) { case "Main Category 1": $main="79"; break; case "Main Category 2": $main="83"; break; case "Main Category 3": $main="87"; break; } However I am struggling as to how to handle other. This stops the whole page loading with no error message switch ($second_cat) { case "Database": $second="145"; break; case "Development": $second="146"; break; case "Other": if ($main_cat) == 'Main Category 1' { $second="147";} break; } This doesn't work at all, second is not changed. switch ($second_cat) { case "Database": $second="145"; break; case "Development": $second="146"; break; case "Other": switch ($main_cat) { case "Main Category 1": $second="147"; break; } }

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  • anti-if campaign

    - by Andrew Siemer
    I recently ran against a very interesting site that expresses a very interesting idea - the anti-if campaign. You can see this here at www.antiifcampaign.com. I have to agree that complex nested IF statements are an absolute pain in the rear. I am currently on a project that up until very recently had some crazy nested IFs that scrolled to the right for quite a ways. We cured our issues in two ways - we used Windows Workflow Foundation to address routing (or workflow) concerns. And we are in the process of implementing all of our business rules utilizing ILOG Rules for .NET (recently purchased by IBM!!). This for the most part has cured our nested IF pains...but I find myself wondering how many people cure their pains in the manner that the good folks at the AntiIfCampaign suggest (see an example here) by creating numerous amounts of abstract classes to represent a given scenario that was originally covered by the nested IF. I wonder if another way to address the removal of this complexity might also be in using an IoC container such as StructureMap to move in and out of different bits of functionality. Either way... Question: Given a scenario where I have a nested complex IF or SWITCH statement that is used to evaluate a given type of thing (say evaluating an Enum) to determine how I want to handle the processing of that thing by enum type - what are some ways to do the same form of processing without using the IF or SWITCH hierarchical structure? public enum WidgetTypes { Type1, Type2, Type3, Type4 } ... WidgetTypes _myType = WidgetTypes.Type1; ... switch(_myType) { case WidgetTypes.Type1: //do something break; case WidgetTypes.Type2: //do something break; //etc... }

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  • Howto use predicates in LINQ to Entities for Entity Framework objects

    - by user274947
    I'm using LINQ to Entities for Entity Framework objects in my Data Access Layer. My goal is to filter as much as I can from the database, without applying filtering logic on in-memory results. For that purpose Business Logic Layer passes a predicate to Data Access Layer. I mean Func<MyEntity, bool> So, if I use this predicate directly, like public IQueryable<MyEntity> GetAllMatchedEntities(Func<MyEntity, Boolean> isMatched) { return qry = _Context.MyEntities.Where(x => isMatched(x)); } I'm getting the exception [System.NotSupportedException] --- {"The LINQ expression node type 'Invoke' is not supported in LINQ to Entities."} Solution in that question suggests to use AsExpandable() method from LINQKit library. But again, using public IQueryable<MyEntity> GetAllMatchedEntities(Func<MyEntity, Boolean> isMatched) { return qry = _Context.MyEntities.AsExpandable().Where(x => isMatched(x)); } I'm getting the exception Unable to cast object of type 'System.Linq.Expressions.FieldExpression' to type 'System.Linq.Expressions.LambdaExpression' Is there way to use predicate in LINQ to Entities query for Entity Framework objects, so that it is correctly transformed it into a SQL statement. Thank you.

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  • How to reference var from frame on timeline in an object class

    - by brybam
    I'm using Flash Professional cs5/AS3 I'll try and describe this the best I can. I'm new to ActionScript. So, in my timeline I have a var on a frame that represents "lives" and i have some code in the timeline that takes down the number of lives depending on certain events, which all works great. so, now i wanted to make a constructor class that I could reuse for a bunch of movie clip objects and I only want these objects to be able to move if the lives variable is greater than certain number. So now, building my constructor class for these objects i just wanted put an if statement that is looking to see if the lives are greater than a certain number, which if it is then should make these objects do what i want...But, when i run the project I get "1120: Access of undefined property lives." lives is the var I made obviously like I said, and it works fine being referenced everyone else except when I make a new .as file for these objects then try and reference it. I get the same error when I try and establish "lives" in the main project class too. I'm not sure where I should put this var or how I can make it so i can reference it from an object class. I'm not really sure how to word or describe my issue which has made it hard to search for a tutorial. Any suggestions i'm sure this has to be a simple task.

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