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• Help creating a predicate for use with filteredArrayUsingPredicate

  - by johnbdh

  I am trying to learn how to use predicates and so am trying to replace the following working code with filteredArrayUsingPredicate... [filteredLocations removeAllObjects]; for (NSString *location in locations) { NSRange range = [location rangeOfString:query options:NSCaseInsensitiveSearch]; if (range.length > 0) { [filteredLocations addObject:location]; } } Instead I am trying.... [filteredLocations removeAllObjects]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF contains %@", searchText]; [filteredLocations addObjectsFromArray: [locations filteredArrayUsingPredicate:predicate]]; I am not getting the same results with the predicate as I am with for loop rangeOfString. With the range of string for example searchText returns an 8 item array while with the same value returns only 2 with the predicate. Another example, hono will find honolulu in the locations array while it will not find anything using the predicate. As I understand it SELF represents the object object being evaluated ie. the locations array, so I think that is the correct syntax. Any help would be appreciated Thanks, John

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• Two-phase lookup: can I avoid "code bloat"?

  - by Pietro

  Two-phase lookup question: Is there a more synthetic way to write this code, i.e. avoiding all those "using" directives? I tried with "using CBase<T>;", but it is not accepted. #include <iostream> template <typename T> class CBase { protected: int a, b, c, d; // many more... public: CBase() { a = 123; } }; template <typename T> class CDer : public CBase<T> { // using CBase<T>; // error, but this is what I would like using CBase<T>::a; using CBase<T>::b; using CBase<T>::c; //... public: CDer() { std::cout << a; } }; int main() { CDer<int> cd; } In my real code there are many more member variables/functions, and I was wondering if it is possible to write shorter code in some way. Of course, using the CBase::a syntax does not solve the problem... Thank's! gcc 4.1 MacOS X 10.6

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• Problems when I try to see databases in SQLite

  - by Sabau Andreea

  I created in code a database and two tables: static final String dbName="graficeCirculatie"; static final String ruteTable="Rute"; static final String colRuteId="RutaID"; static final String colRuta="Ruta"; static final String statiaTable="Statia"; static final String colStatiaID="StatiaID"; static final String colIdRuta="IdRuta"; static final String colStatia="Statia"; public DatabaseHelper(Context context) { super(context, dbName, null,33); } public void onCreate(SQLiteDatabase db) { // TODO Auto-generated method stub db.execSQL("CREATE TABLE " + statiaTable + " (" + colStatiaID + " INTEGER PRIMARY KEY , " + colIdRuta + " INTEGER, " + colStatia + " TEXT)"); db.execSQL("CREATE TABLE " + ruteTable + "(" + colRuteId + " INTEGER PRIMARY KEY AUTOINCREMENT, " + colRuta + " TEXT);"); InsertDepts(db); } void InsertDepts(SQLiteDatabase db) { ContentValues cv = new ContentValues(); cv.put(colRuteId, 1); cv.put(colRuta, "Expres8"); db.insert(ruteTable, colRuteId, cv); cv.put(colRuteId, 2); cv.put(colRuta, "Expres2"); db.insert(ruteTable, colRuteId, cv); cv.put(colRuteId, 3); cv.put(colRuta, "Expres3"); db.insert(ruteTable, colRuteId, cv); } Now I want to see tables inputs from command line. I try in this way: C:\Program Files\Android\android-sdk\tools sqlite3 SQLite version 3.7.4 Enter ".help" for instructions Enter SQL statements terminated with a ";" sqlite sqlite3 graficeCirculatie ... select * from ruteTable; And I got an error: Error: near "squlite3": syntax error. Can someone help me?

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• Problem with Silverlight 3 projects in Web Developer Express 2008

  - by MNT

  Hi, I have a strange problem when working with silverlight 3 projects in Web Developer Express 2008. Mainly, I cannot show the design view of a XAML file. Also the XAML files (markup) are shown as plain text files (No Syntax coloring & No Intellisense). However I can write an application that is compiled and run successfully. I have the following installed on my machine: Windows XP SP3 Visual Web Developer Express 2008 SP1 & .NET 3.5 SP1 SL3 Requirements I had a few problems while installing SL3 SDK & Tool for VS. I repeated the process many times until the installation succeeded. The main problem was in the "SL Tools for VS" installation where I used to get an error in the middle. My workaround was to extract the MSI file and manually run the VWDxxx installer from the extracted files. Is this the cause of the problem? Kindly advise as it's impractical to work w/o Intellisense. Thnak you

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• How can I test this SQL Server performance Utility?

  - by Martin Smith

  As part of my MSc I need to do a three month project later this year. I have decided to do something which will likely be useful for me in the workplace and spend the time getting to understand SQL Server internals. The deliverable for this project will be a performance advisor looking at a variety of different rules. Some static such as finding redundant indexes, some more dynamic such as using XEvents to find outlying invocations of stored procedure execution times when certain parameters are passed. I am struggling to come up with a good way of testing this though. I can obviously design a "bad" database and a synthetic workload that my tool will pick up issues on but I also need to demonstrate that it has real world utility. Looking at the self tuning database literature it is common to use TPC benchmarks but I've had a look at the TPCC site and it looks very time consuming to implement and not that good a fit to my project's testing needs in any event (I would still be able to "rig" it by the decisions I made on indexing or physical architecture). Plan A would be to find willing beta tester(s) but in the event that isn't possible I will need a fallback plan. The best idea I have come up with so far is to use the various MS sample applications as examples of real world applications. e.g. http://msftdpprodsamples.codeplex.com/ http://www.asp.net/community/projects/ Does anyone have any better suggestions?

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• ibm informix spatial datablade select statement error

  - by changed

  Hi I am using IBM informix spatial datablade module for some geo specific data. I am trying to find points in table xmlData lying in a specified region. But i am getting this error for select statement. SELECT sa.pre, sa.post FROM xmlData sa WHERE ST_Contains( ST_PolyFromText('polygon((2 2,6 2,6 6,2 6,2 2))',6),sa.point) Query: select count(*) as mycnt fromText('polygon((2 2,6 2,6 6,2 6,2 2))',6),sa.point) Error: -201 [Informix][Informix ODBC Driver][Informix]A syntax error has occurred. (SQLPrepare[-201] at /work/lwchan/workspace/OATPHPcompile/pdo_informix/pdo_informix/informix_driver.c:131) If any one can help me with this. CREATE TABLE xmlData (row_id integer NOT NULL, x integer, y integer, tagname varchar(40,1), point ST_POINT ); EXECUTE FUNCTION SE_CreateSRID(0, 0, 250000, 250000, "use the return value in next query last column"); INSERT INTO geometry_columns (f_table_catalog, f_table_schema, f_table_name, f_geometry_column, geometry_type, srid) VALUES ("mydatabase", -- database name "informix", -- user name "xmlData", -- table name "point", -- spatial column name 1, -- column type (1 = point) 6); -- srid //use value returned by above query. INSERT INTO xmlData VALUES ( 1, 20,20, 'country', ST_PointFromText('point (20 20)',6) ); INSERT INTO xmlData VALUES ( 1, 12,13, 'sunday', ST_PointFromText('point (12 13)',6) ); INSERT INTO xmlData VALUES ( 1, 21,22, 'monday', ST_PointFromText('point (21 22)',6) ); SELECT sa.pre, sa.post FROM xmlData sa WHERE ST_Contains( ST_PolyFromText('polygon((1 1,30 1,30 30,1 30,1 1))', 6),sa.point); I am using following query as reference "ibm link". SELECT name, type, zone FROM sensitive_areas WHERE SE_EnvelopesIntersect(zone, ST_PolyFromText('polygon((20000 20000,60000 20000,60000 60000,20000 60000,20000 20000))', 5));

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• bash and flock (file lock) - Doesn't seem to be locking....

  - by Rory

  I am playing with using flock, a bash command for file locks to prevent 2 different instances of the code from running more than once. I am using this testing code: ( ( flock -x 200 ; sleep 10 ; echo "original finished" ; ) 200>./test.lock ) & ( sleep 2 ; ( flock -x -w 2 200 ; echo "a finished" ) 200>./test.lock ) & I am running 2 subshells (backgrounded). The (flock NUM; ...) NUM>FILE syntax is from flock's man page. I expect that the first subshell will get an exclusive lock on test.lock, then wait 10 seconds, then print "original finished", all the time holding the lock. The second subshell will start at more or less the same time, wait 2 seconds, then try to get a lock on test.lock, but timeout after 2 seconds. If it gets a lock, then it'll print "a finished". If it doesn't get the lock, that subshell should stop, and nothing should be printed. Since the first subshell is waiting longer, it will keep the lock for 10 seconds, so the second subshell should not get the lock, and shouldn't finish. i.e. one should see "original finished" printed and not both. What actually happens is that "a finished" is printed, then "original finished" is printed. This implies that that the second subshell is either (a) not using the same lock as the first subhsell or (b) that it fails to get the lock, but continues to execute or (c) something else. Why don't those locks work?

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• Rename a file with perl

  - by perlnoob

  I have a file in a different folder I want to rename in perl, I was looking at a solution earlier that showed something like this: for (<backup.rar>) { my $file = $_; my $new = $_ 'backup'. @test .'.rar'; rename $file, $new or die "Error, can not rename $file as $new: $!"; } however backup.rar is in a different folder, I did try putting "C:\backup\backup.rar" in the < above, however I got the same error. C:\Program Files\WinRARperl backup.pl String found where operator expected at backup.pl line 35, near "$_ 'backup'" (Missing operator before 'backup'?) syntax error at backup.pl line 35, near "$_ 'backup'" Execution of backup.pl aborted due to compilation errors. I was using # Get time my @test = POSIX::strftime("%m-%d-%Y--%H-%M-%S\n", localtime); print @test; To get the current time, however I couldn't seem to get it to rename correctly. What can I do to fix this? Please note I am doing this on a windows box.

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• PHP site keeps opening to blank page, no errors.

  - by gene

  First, the premises: PHP loaded on IIS6 on Win2003 STD R2 SP2, PHP_5213 using FastCGI, MySQL_5145. Customer sent me the site files, which I unzipped to C:\InetPub\wwwroot\<site root>, then I created a new site in IIS, pointed to <site root>, added test.php to the site files for testing and it works, but visiting index.php produces a blank page with no errors. The readme.txt file present makes reference to application.php and explains root folder var and sets it to a non-existent file. I don't know PHP syntax, but I tried several logical changes with zero results. At this point I'm not even sure if that is the problem anymore. With PHP, MySQL & site debugging have put in over 20 hours. Still confused, I have resorted to heavy drug use and purchased a small firearm, loaded with a single round (even this seemed to take an inordinate amount of time). I've given up all hope. Someone please help save a new server and/or old administrator.

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• Need some advice on Core Data modeling strategy

  - by Andy

  I'm working on an iPhone app and need a little advice on modeling the Core Data schema. My idea is a utility that allows the user to speed-dial their contacts using user-created rules based on the time of day. In other words, I would tell the app that my wife is commuting from 6am to 7am, at work from 7am to 4pm, commuting from 4pm to 5pm, and home from 5pm to 6am, Monday through Friday. Then, when I tap her name in my app, it would select the number to dial based on the current day and time. I have the user interface nearly complete (thanks in no small part to help I've received here), but now I've got some questions regarding the persistent store. The user can select start- and stop-times in 5-minute increments. This means there are 2,016 possible "time slots" in week (7 days * 24 hours * 12 5-minute intervals per hour). I see a few options for setting this up. Option #1: One array of time slots, with 2,016 entries. Each entry would be a dictionary containing a contact identifier and an associated phone number to dial. I think this means I'd need a "Contact" entity to store the contact information, and a "TimeSlot" entity for each of the 2,016 possible time slots. Option #2: Each Contact has its own array of time slots, each with 2,016 entries. Each array entry would simply be a string indicating which phone number to dial. Option #3: Each Contact has a dictionary of time slots. An entry would only be added to the dictionary for time slots with an active rule. If a search for, say, time slot 1,299 (Friday 12:15pm) didn't find a key @"1299" in the dictionary, then a default number would be dialed instead. I'm not sure any of these is the "right" way or the "best" way. I'm not even sure I need to use Core Data to manage it; maybe just saving arrays would be simpler. Any input you can offer would be appreciated.

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• Use Objective-C without NSObject?

  - by Alex I

  I am testing some simple Objective-C code on Windows (cygwin, gcc). This code already works in Xcode on Mac. I would like to convert my objects to not subclass NSObject (or anything else, lol). Is this possible, and how? What I have so far: // MyObject.h @interface MyObject - (void)myMethod:(int) param; @end and // MyObject.m #include "MyObject.h" @interface MyObject() { // this line is a syntax error, why? int _field; } @end @implementation MyObject - (id)init { // what goes in here? return self; } - (void)myMethod:(int) param { _field = param; } @end What happens when I try compiling it: gcc -o test MyObject.m -lobjc MyObject.m:4:1: error: expected identifier or ‘(’ before ‘{’ token MyObject.m: In function ‘-[MyObject myMethod:]’: MyObject.m:17:3: error: ‘_field’ undeclared (first use in this function) EDIT My compiler is cygwin's gcc, also has cygwin gcc-objc package: gcc --version gcc (GCC) 4.7.3 I have tried looking for this online and in a couple of Objective-C tutorials, but every example of a class I have found inherits from NSObject. Is it really impossible to write Objective-C without Cocoa or some kind of Cocoa replacement that provides NSObject? (Yes, I know about GNUstep. I would really rather avoid that if possible...)

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• How would you design a question/answer view (iPhone SDK)

  - by Aurélien Vallée

  I'm new to iPhone development, and I have a question on how to create a view for my application. The view should display a problem (using formatted/syntax highlighted text), and multiple possible answers. The user should be able to click on an answer to validate it. Currently, I am trying to use a UITableView embedding UIWebView as contentView. That allows me to display formatted text easily. The problem is that it is a real pain to compute and adjust the height of the cells. I have to preload the webview, call sizeToFit, get its height, and update the cell accordingly. This process should be done for the problem and the answers (as they are HTML formatted text too). It's such a pain that I am planning to switch to something else. I thought using only a big UIWebView and design everything in HTML. But I looked at some articles describing how to communicate between the HTML page and the ObjectiveC code. This seems to involve some awful tricks too... So... that's it, I don't really know what I should do. I guess some of you dealt with such things before, and would provide some greatly appreciated tips :)

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• Best approach, Dynamic OpenXML in T-SQL

  - by Martin Ongtangco

  hello, i'm storing XML values to an entry in my database. Originally, i extract the xml datatype to my business logic then fill the XML data into a DataSet. I want to improve this process by loading the XML right into the T-SQL. Instead of getting the xml as string then converting it on the BL. My issue is this: each xml entry is dynamic, meaning it can be any column created by the user. I tried using this approach, but it's giving me an error: CREATE PROCEDURE spXMLtoDataSet @id uniqueidentifier, @columns varchar(max) AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; DECLARE @name varchar(300); DECLARE @i int; DECLARE @xmlData xml; (SELECT @xmlData = data, @name = name FROM XmlTABLES WHERE (tableID = ISNULL(@id, tableID))); EXEC sp_xml_preparedocument @i OUTPUT, @xmlData DECLARE @tag varchar(1000); SET @tag = '/NewDataSet/' + @name; DECLARE @statement varchar(max) SET @statement = 'SELECT * FROM OpenXML(@i, @tag, 2) WITH (' + @columns + ')'; EXEC (@statement); EXEC sp_xml_removedocument @i END where i pass a dynamically written @columns. For example: spXMLtoDataSet 'bda32dd7-0439-4f97-bc96-50cdacbb1518', 'ID int, TypeOfAccident int, Major bit, Number_of_Persons int, Notes varchar(max)' but it kept on throwing me this exception: Msg 137, Level 15, State 2, Line 1 Must declare the scalar variable "@i". Msg 319, Level 15, State 1, Line 1 Incorrect syntax near the keyword 'with'. If this statement is a common table expression or an xmlnamespaces clause, the previous statement must be terminated with a semicolon.

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• How to compile ocaml to native code

  - by Indra Ginanjar

  i'm really interested learning ocaml, it fast (they said it could be compiled to native code) and it's functional. So i tried to code something easy like enabling mysql event scheduler. #load "unix.cma";; #directory "+mysql";; #load "mysql.cma";; let db = Mysql.quick_connect ~user:"username" ~password:"userpassword" ~database:"databasename"();; let sql = Printf.sprintf "SET GLOBAL EVENT_SCHEDULER=1;" in (Mysql.exec db sql);; It work fine on ocaml interpreter, but when i was trying to compile it to native (i'm using ubuntu karmic), neither of these command worked ocamlopt -o mysqleventon mysqleventon.ml unix.cmxa mysql.cmxa ocamlopt -o mysqleventon mysqleventon.ml unix.cma mysql.cma i also tried ocamlc -c mysqleventon.ml unix.cma mysql.cma all of them resulting same message File "mysqleventon.ml", line 1, characters 0-1: Error: Syntax error Then i tried to remove the "# load", so the code goes like this let db = Mysql.quick_connect ~user:"username" ~password:"userpassword" ~database:"databasename"();; let sql = Printf.sprintf "SET GLOBAL EVENT_SCHEDULER=1;" in (Mysql.exec db sql);; The ocamlopt resulting message File "mysqleventon.ml", line 1, characters 9-28: Error: Unbound value Mysql.quick_connect I hope someone could tell me, where did i'm doing wrong.

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• SubSonic 3.0 Simple Repository Adding a DateTime Property To An Object

  - by Blounty

  I am trying out SubSonic to see if it is viable to use on production projects. I seem to have stumbled upon an issue whith regards to updating the database with default values (String and DateTime) when a new column is created. If a new property of DateTime or String is added to an object. public class Bug { public int BugId { get; set; } public string Title { get; set; } public string Overview { get; set; } public DateTime TrackedDate { get; set; } public DateTime RemovedDate { get; set; } } When the code to add that type of object to the database is run var repository = new SimpleRepository(SimpleRepositoryOptions.RunMigrations); repository.Add(new Bug() { Title = "A Bug", Overview = "An Overview", TrackedDate = DateTime.Now }); it creates the following sql: UPDATE Bugs SET RemovedDate=''01/01/1900 00:00:00'' For some reason it is adding double 2 single quotes to each end of the string or DateTime. This is causing the following error: System.Data.SqlClient.SqlException - Incorrect syntax near '01' I am connecting to SQL Server 2005 Any help would be appreicated as apart from this issue i am finding SubSonic to be a great product. I have created a screen cast of my error here:

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• What does it mean that "Lisp can be written in itself?"

  - by Mason Wheeler

  Paul Graham wrote that "The unusual thing about Lisp-- in fact, the defining quality of Lisp-- is that it can be written in itself." But that doesn't seem the least bit unusual or definitive to me. ISTM that a programming language is defined by two things: Its compiler or interpreter, which defines the syntax and the semantics for the language by fiat, and its standard library, which defines to a large degree the idioms and techniques that skilled users will use when writing code in the language. With a few specific exceptions, (the non-C# members of the .NET family, for example,) most languages' standard libraries are written in that language for two very good reasons: because it will share the same set of syntactical definitions, function calling conventions, and the general "look and feel" of the language, and because the people who are likely to write a standard library for a programming language are its users, and particularly its designer(s). So there's nothing unique there; that's pretty standard. And again, there's nothing unique or unusual about a language's compiler being written in itself. C compilers are written in C. Pascal compilers are written in Pascal. Mono's C# compiler is written in C#. Heck, even some scripting languages have implementations "written in itself". So what does it mean that Lisp is unusual in being written in itself?

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• Reformat SQLGeography polygons to JSON

  - by James

  I am building a web service that serves geographic boundary data in JSON format. The geographic data is stored in an SQL Server 2008 R2 database using the geography type in a table. I use [ColumnName].ToString() method to return the polygon data as text. Example output: POLYGON ((-6.1646509904325884 56.435153006374627, ... -6.1606079906751 56.4338050060666)) MULTIPOLYGON (((-6.1646509904325884 56.435153006374627 0 0, ... -6.1606079906751 56.4338050060666 0 0))) Geographic definitions can take the form of either an array of lat/long pairs defining a polygon or in the case of multiple definitions, an array or polygons (multipolygon). I have the following regex that converts the output to JSON objects contained in multi-dimensional arrays depending on the output. Regex latlngMatch = new Regex(@"(-?[0-9]{1}\.\d*)\s(\d{2}.\d*)(?:\s0\s0,?)?", RegexOptions.Compiled); private string ConvertPolysToJson(string polysIn) { return this.latlngMatch.Replace(polysIn.Remove(0, polysIn.IndexOf("(")) // remove POLYGON or MULTIPOLYGON .Replace("(", "[") // convert to JSON array syntax .Replace(")", "]"), // same as above "{lng:$1,lat:$2},"); // reformat lat/lng pairs to JSON objects } This is actually working pretty well and converts the DB output to JSON on the fly in response to an operation call. However I am no regex master and the calls to String.Replace() also seem inefficient to me. Does anyone have any suggestions/comments about performance of this?

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• Using PHP to display button with hyperlink or greyed out button if no URL in database

  - by Diane

  I've got a webpage that I'm working on where you click on a letter or category and it displays records matching that query from a database. One of the things I want to display is a hyperlinked button that says "Website" if the database record contains a URL in the 'URL' field, and if there is no value in that field, it will display a greyed out version of that button. I tried using an if...else statement, but was absolutely unable to get the syntax correct trying to get php to call up the 'URL' value in the middle of an "echo " So here's what I did: <?php if($row_rsmemalpha['URL'] != NULL) ?><a href="http://<?php echo ($row_rsmemalpha['URL']);?>"><target ="_blank"><img src="web_button_on.gif" alt="Website" border="0" height="18" width="103" /></target></a> <?php if($row_rsmemalpha['URL'] == NULL) echo "<img src=\"web_button_off.gif\" alt=\"No Website Available\" height=\"18\" width=\"103\" />"; ?> If there is a URL available it shows the button properly. But if there isn't a URL in the database it shows both buttons. I have spent a few days studying examples and tutorials on the web, but haven't found too much that helps. The buttons were completely non-functional when I started, so I'm pretty proud of getting this far with it! I've just run out of time and patience for more trial-and-error experimenting. Any help is appreciated... Diane

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• Simplest way to handle and display errors in a Python Pylons controller without a helper class

  - by ensnare

  I have a class User() that throw exceptions when attributes are incorrectly set. I am currently passing the exceptions from the models through the controller to the templates by essentially catching exceptions two times for each variable. Is this a correct way of doing it? Is there a better (but still simple) way? I prefer not to use any third party error or form handlers due to the extensive database queries we already have in place in our classes. Furthermore, how can I "stop" the chain of processing in the class if one of the values is invalid? Is there like a "break" syntax or something? Thanks. >>> u = User() >>> u.name = 'Jason Mendez' >>> u.password = '1234' Traceback (most recent call last): File "<stdin>", line 1, in <module> File "topic/model/user.py", line 79, in password return self._password ValueError: Your password must be greater than 6 characters In my controller "register," I have: class RegisterController(BaseController): def index(self): if request.POST: c.errors = {} u = User() try: u.name = c.name = request.POST['name'] except ValueError, error: c.errors['name'] = error try: u.email = c.email = request.POST['email'] except ValueError, error: c.errors['email'] = error try: u.password = c.password = request.POST['password'] except ValueError, error: c.errors['password'] = error try: u.commit() except ValueError, error: pass return render('/register.mako')

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• Javascript for loop with variable

  - by Jascination

  I'm doing some simple javascript learning at the moment and I'm stuck on how to solve this problem. (the basic form comes from Code Academy). The task is to create 3 rabbit objects, each with a different adjective as an attribute. Then, print describeMyself() for each rabbit. Instead of repeating myself 3 times, I'd like to find a way to solve the problem with a for loop to make it more streamlined/challenging for myself. Here's what I tried: function Rabbit(adjective) { this.adjective = adjective; this.describeMyself = function() { console.log("I am a " + this.adjective + " rabbit"); }; } var rabbit1 = new Rabbit(fluffy); var rabbit2 = new Rabbit(happy); var rabbit3 = new Rabbit(sleepy); for (i=1; i<=3; i++){ ("rabbit"+i).describeMyself(); } Obviously, the ("rabbit"+i).describeMyself() is wrong. I want the loop to create "rabbit1", "rabbit2" and "rabbit3". What's the proper syntax here?

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• Why is Collection<String>.class Illegal?

  - by Peter

  I am puzzled by generics. You can declare a field like: Class<Collection<String>> clazz = ... It seems logical that you could assign this field with: Class<Collection<String>> clazz = Collection<String>.class; However, this generates an error: Syntax error on token ">", void expected after this token So it looks like the .class operator does not work with generics. So I tried: class A<S> {} class B extends A<String> {} Class<A<String>> c = B.class; Also does not work, generates: Type mismatch: cannot convert from Class<Test.StringCollection> to Class<Collection<String>> Now, I really fail to see why this should not work. I know generic types are not reified but in both cases it seems to be fully type safe without having access to runtime generic types. Anybody an idea? Peter Kriens

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• Why This Maintainability Index Increase?

  - by Timothy

  I would be appreciative if someone could explain to me the difference between the following two pieces of code in terms of Visual Studio's Code Metrics rules. Why does the Maintainability Index increase slightly if I don't encapsulate everything within using ( )? Sample 1 (MI score of 71) public static String Sha1(String plainText) { using (SHA1Managed sha1 = new SHA1Managed()) { Byte[] text = Encoding.Unicode.GetBytes(plainText); Byte[] hashBytes = sha1.ComputeHash(text); return Convert.ToBase64String(hashBytes); } } Sample 2 (MI score of 73) public static String Sha1(String plainText) { Byte[] text, hashBytes; using (SHA1Managed sha1 = new SHA1Managed()) { text = Encoding.Unicode.GetBytes(plainText); hashBytes = sha1.ComputeHash(text); } return Convert.ToBase64String(hashBytes); } I understand metrics are meaningless outside of a broader context and understanding, and programmers should exercise discretion. While I could boost the score up to 76 with return Convert.ToBase64String(sha1.ComputeHash(Encoding.Unicode.GetBytes(plainText))), I shouldn't. I would clearly be just playing with numbers and it isn't truly any more readable or maintainable at that point. I am curious though as to what the logic might be behind the increase in this case. It's obviously not line-count.

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• Why put a DAO layer over a persistence layer (like JDO or Hibernate)

  - by Todd Owen

  Data Access Objects (DAOs) are a common design pattern, and recommended by Sun. But the earliest examples of Java DAOs interacted directly with relational databases -- they were, in essence, doing object-relational mapping (ORM). Nowadays, I see DAOs on top of mature ORM frameworks like JDO and Hibernate, and I wonder if that is really a good idea. I am developing a web service using JDO as the persistence layer, and am considering whether or not to introduce DAOs. I foresee a problem when dealing with a particular class which contains a map of other objects: public class Book { // Book description in various languages, indexed by ISO language codes private Map<String,BookDescription> descriptions; } JDO is clever enough to map this to a foreign key constraint between the "BOOKS" and "BOOKDESCRIPTIONS" tables. It transparently loads the BookDescription objects (using lazy loading, I believe), and persists them when the Book object is persisted. If I was to introduce a "data access layer" and write a class like BookDao, and encapsulate all the JDO code within this, then wouldn't this JDO's transparent loading of the child objects be circumventing the data access layer? For consistency, shouldn't all the BookDescription objects be loaded and persisted via some BookDescriptionDao object (or BookDao.loadDescription method)? Yet refactoring in that way would make manipulating the model needlessly complicated. So my question is, what's wrong with calling JDO (or Hibernate, or whatever ORM you fancy) directly in the business layer? Its syntax is already quite concise, and it is datastore-agnostic. What is the advantage, if any, of encapsulating it in Data Access Objects?

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• Which Table Should be Master and Child in Database Design

  - by Jason

  I am quickly learning the ins and outs of database design (something that, as of a week ago, was new to me), but I am running across some questions that don't seem immediately obvious, so I was hoping to get some clarification. The question I have right is about foreign keys. As part of my design, I have a Company table. Originally, I had included address information directly within the table, but, as I was hoping to achieve 3NF, I broke out the address information into its own table, Address. In order to maintain data integrity, I created a row in Company called "addressId" as an INT and the Address table has a corresponding addressId as its primary key. What I'm a little bit confused about (or what I want to make sure I'm doing correctly) is determining which table should be the master (referenced) table and which should be the child (referencing) table. When I originally set this up, I made the Address table the master and the Company the child. However, I now believe this is wrong due to the fact that there should be only one address per Company and, if a Company row is deleted, I would want the corresponding Address to be removed as well (CASCADE deletion). I may be approaching this completely wrong, so I would appreciate any good rules of thumb on how to best think about the relationship between tables when using foreign keys. Thanks!

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• How does the last integer promotion rule ever get applied in C?

  - by SiegeX

  6.3.1.8p1: Otherwise, the integer promotions are performed on both operands. Then the following rules are applied to the promoted operands: If both operands have the same type, then no further conversion is needed. Otherwise, if both operands have signed integer types or both have unsigned integer types, the operand with the type of lesser integer conversion rank is converted to the type of the operand with greater rank. Otherwise, if the operand that has unsigned integer type has rank greater or equal to the rank of the type of the other operand, then the operand with signed integer type is converted to the type of the operand with unsigned integer type. Otherwise, if the type of the operand with signed integer type can represent all of the values of the type of the operand with unsigned integer type, then the operand with unsigned integer type is converted to the type of the operand with signed integer type. Otherwise, both operands are converted to the unsigned integer type corresponding to the type of the operand with signed integer type. For the bolded rule to be applied it would seem to imply you need to have have an unsigned interger type who's rank is less than the signed integer type and the signed integer type cannot hold all the values of the unsigned integer type. Is there a real world example of such a case or is this statement serving as a catch-all to cover all possible permutations?

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