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• "Invalid use of Null" when using Str() with a Null Recordset field, but Str(Null) works fine

  - by Mike Spross

  I'm banging my head against the wall on this one. I was looking at some old database reporting code written in VB6 and case across this line (the code is moving data from a "source" database into a reporting database): rsTarget!VehYear = Trim(Str(rsSource!VehYear)) When rsSource!VehYear is Null, the above line generates an "Invalid use of Null" run-time error. If I break on the above line and type the following in the Immediate pane: ?rsSource!VehYear It outputs Null. Fine, that makes sense. Next, I try to reproduce the error: ?Str(rsSource!VehYear) I get an "Invalid use of Null" error. However, if I type the following into the Immediate window: ?Str(Null) I don't get an error. It simply outputs Null. If I repeat the same experiment with Trim() instead of Str(), everything works fine. ?Trim(rsSource!VehYear) returns Null, as does ?Trim(Null). No run-time errors. So, my question is, how can Str(rsSource!VehYear) possibly throw an "Invalid use of Null" error when Str(Null) does not, when I know that rsSource!VehYear is equal to Null?

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• Pattern for version-specific implementations of a Java class

  - by Mike Monkiewicz

  So here's my conundrum. I am programming a tool that needs to work on old versions of our application. I have the code to the application, but can not alter any of the classes. To pull information out of our database, I have a DTO of sorts that is populated by Hibernate. It consumes a data object for version 1.0 of our app, cleverly named DataObject. Below is the DTO class. public class MyDTO { private MyWrapperClass wrapper; public MyDTO(DataObject data) { wrapper = new MyWrapperClass(data); } } The DTO is instantiated through a Hibernate query as follows: select new com.foo.bar.MyDTO(t1.data) from mytable t1 Now, a little logic is needed on top of the data object, so I made a wrapper class for it. Note the DTO stores an instance of the wrapper class, not the original data object. public class MyWrapperClass { private DataObject data; public MyWrapperClass(DataObject data) { this.data = data; } public String doSomethingImportant() { ... version-specific logic ... } } This works well until I need to work on version 2.0 of our application. Now DataObject in the two versions are very similar, but not the same. This resulted in different sub classes of MyWrapperClass, which implement their own version-specific doSomethingImportant(). Still doing okay. But how does myDTO instantiate the appropriate version-specific MyWrapperClass? Hibernate is in turn instantiating MyDTO, so it's not like I can @Autowire a dependency in Spring. I would love to reuse MyDTO (and my dozens of other DTOs) for both versions of the tool, without having to duplicate the class. Don't repeat yourself, and all that. I'm sure there's a very simple pattern I'm missing that would help this. Any suggestions?

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• Symfony 1.4 - Don't save a blank password on a executeUpdate action.

  - by Twelve47

  I have a form to edit a UserProfile which is stored in mysql db. Which includes the following custom configuration: public function configure() { $this->widgetSchema['password']=new sfWidgetFormInputPassword(); $this->validatorSchema['password']->setOption('required', false); // you don't need to specify a new password if you are editing a user. } When the user tries to save the executeUpdate method is called to commit the changes. If the password is left blank, the password field is set to '', but I want it to retain the old password instead of overwriting it. What is the best (/most in the symfony ethos) way of doing this? My solution was to override the setter method on the model (which i had done anyway for password encryption), and ignore blank values. public function setPassword( $password ) { if ($password=='') return false; // if password is blank don't save it. return $this->_set('password', UserProfile ::encryptPassword( $password )); } It seems to work fine like this, but is there a better way? If you're wondering I cannot use sfDoctrineGuard for this project as I am dealing with a legacy database, and cannot change the schema.

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• Is it a bug???????????????/

  - by Knowing me knowing you

  I'm using VS2010 Ultimate. Having code: //file IntSet.h #include "stdafx.h" #pragma once /*Class representing set of integers*/ template<class T> class IntSet { private: T** myData_; std::size_t mySize_; std::size_t myIndex_; public: #pragma region ctor/dtor explicit IntSet(); virtual ~IntSet(); #pragma endregion #pragma region publicInterface IntSet makeUnion(const IntSet&)const; IntSet makeIntersection(const IntSet&)const; IntSet makeSymmetricDifference(const IntSet&)const; void insert(const T&); #pragma endregion }; //file IntSet_impl.h #include "StdAfx.h" #include "IntSet.h" #pragma region ctor/dtor template<class T> IntSet<T>::IntSet():myData_(nullptr), mySize_(0), myIndex_(0) { } template<class T> IntSet<T>::~IntSet() { } #pragma endregion #pragma region publicInterface template<class T> void IntSet<T>::insert(const T& obj) {/*IF I SET A BREAKPOINT HERE AND AFTER THAT I CHANGE SOMETHING IN THE BODY I'M GETTING MSG SAYING THAT THE BREAKPOINT WILL NOT CURRENTLY BE HIT, AFTER I REBUILD THE BREAKPOINT IS VALID AGAIN*/ /*Check if we are initialized*/ if (mySize_ == 0) { mySize_ = 1; myData_ = new T*[mySize_]; } /*Check if we have place to insert obj in.*/ if (myIndex_ < mySize_) { myData_[myIndex_++] = new T(obj); return; } /*We didn't have enough place...*/ T** tmp = new T*[mySize_];//for copying old to temporary basket std::copy(&myData_[0],&myData_[mySize_],&tmp[0]); delete myData_; auto oldSize = mySize_; mySize_ *= 2; myData_ = new T*[mySize_]; std::copy(&tmp[0],&tmp[oldSize],&myData_[0]); myData_[myIndex_] = new T(obj); ++myIndex_; } #pragma endregion Thanks.

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• objective-c having issues with an NSDictioary object

  - by Mark

  I have a simple iPhone app that Im learning and I want to have an instance variable called urlLists which is an NSDictionary I have declared it like so: @interface MyViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>{ IBOutlet UIPickerView *pickerView; NSMutableArray *categories; NSDictionary *urlLists; } @property(retain) NSDictionary *urlLists; @end and in the implementation: @implementation MyViewController @synthesize urlLists; ... - (void)viewDidLoad { [super viewDidLoad]; categories = [[NSMutableArray alloc] init]; [categories addObject:@"Sport"]; [categories addObject:@"Entertainment"]; [categories addObject:@"Technology"]; [categories addObject:@"Political"]; NSArray *objects = [NSArray arrayWithObjects:@"value1", @"value2", @"value3", @"value4", nil]; urlLists = [NSDictionary dictionaryWithObjects:objects forKeys:categories]; for (id key in urlLists) { NSLog(@"key: %@, value: %@", key, [urlLists objectForKey:key]); } } ... @end And, this all works up to here. I have added a UIPicker to my app, and when I select one of the items, I want to Log the one picked and its related entry in my dictionary. -(void) pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger) component { for (id key in self.urlLists) { NSLog(@"key: %@, value: %@", key, [urlLists objectForKey:key]); } } but I get the old EXC_BAD_ACCESS error... I know Im missing something small, but what? Thanks

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• Get active window title in X

  - by dutt

  I'm trying to get the title of the active window. The application is a background task so if the user has Eclipse open the function returns "Eclipse - blabla", so it's not getting the window title of my own window. I'm developing this in Python 2.6 using PyQt4. My current solution, borrowed and slightly modified from an old answer here at SO, looks like this: def get_active_window_title(): title = '' root_check = '' root = Popen(['xprop', '-root'], stdout=PIPE) if root.stdout != root_check: root_check = root.stdout for i in root.stdout: if '_NET_ACTIVE_WINDOW(WINDOW):' in i: id_ = i.split()[4] id_w = Popen(['xprop', '-id', id_], stdout=PIPE) for j in id_w.stdout: if 'WM_ICON_NAME(STRING)' in j: if title != j.split()[2]: return j.split("= ")[1].strip(' \n\"') It works for most windows, but not all. For example it can't find my kopete chat windows, or the name of the application i'm currently developing. My next try looks like this: def get_active_window_title(self): screen = wnck.screen_get_default() if screen == None: return "Could not get screen" window = screen.get_active_window() if window == None: return "Could not get window" title = window.get_name() return title; But for some reason window is always None. Does somebody have a better way of getting the current window title, or how to modify one of my ways, that works for all windows? Edit: In case anybody is wondering this is the way I found that seems to work for all windows. def get_active_window_title(self): root_check = '' root = Popen(['xprop', '-root'], stdout=PIPE) if root.stdout != root_check: root_check = root.stdout for i in root.stdout: if '_NET_ACTIVE_WINDOW(WINDOW):' in i: id_ = i.split()[4] id_w = Popen(['xprop', '-id', id_], stdout=PIPE) id_w.wait() buff = [] for j in id_w.stdout: buff.append(j) for line in buff: match = re.match("WM_NAME\((?P<type>.+)\) = (?P<name>.+)", line) if match != None: type = match.group("type") if type == "STRING" or type == "COMPOUND_TEXT": return match.group("name") return "Active window not found"

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• [C#] Dynamic user-interface, WPF or not?

  - by pieter.lowie

  Hi, I'm currently working at a application that helps people understand how to do there job. You can see it as a personal coach that guides them trough all the steps they need to do that no normal person could keep remembering. In my previous application we had the ability to show the user up to 4 pictures (what proves to be more then enough). The application would load the data and see how many pictures where in every instruction and then sort out the picture in the best fitting way without messing up the scale and resolution of the pictures. This all was done with GDI+ and worked very well. Ofc, change is something that always happens, my bosses came up with some great ideas. So they want to be able to see movies on the screen, animated gif's, 3D models that can rotate or animate. So I think we had pushed GDI+ to it's limits and it's time to look for something different. I have heard and readed about WPF but have no experience with it. Is it even possible to do all what I ask in WPF? And what about the old picture-merging thing I wrote, can we also get it done in wpf? I tried to make some things working but I didn't went as smooth as I hoped. I'm also concerned about the fact that the interface needs to be dynamic, the one moment it should be showing picture with some text above it, the other moment it should be showing another text with a video under it. I would love to hear some opinions here and if you got some other suggestions I should look into pls tell me. Thnx in advance PS: If WPF is the choice, should I convince my boss to change to .net 4.0?

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• Faster quadrature decoder loops with Python code

  - by Kelei

  I'm working with a BeagleBone Black and using Adafruit's IO Python library. Wrote a simple quadrature decoding function and it works perfectly fine when the motor runs at about 1800 RPM. But when the motor runs at higher speeds, the code starts missing some of the interrupts and the encoder counts start to accumulate errors. Do you guys have any suggestions as to how I can make the code more efficient or if there are functions which can cycle the interrupts at a higher frequency. Thanks, Kel Here's the code: # Define encoder count function def encodercount(term): global counts global Encoder_A global Encoder_A_old global Encoder_B global Encoder_B_old global error Encoder_A = GPIO.input('P8_7') # stores the value of the encoders at time of interrupt Encoder_B = GPIO.input('P8_8') if Encoder_A == Encoder_A_old and Encoder_B == Encoder_B_old: # this will be an error error += 1 print 'Error count is %s' %error elif (Encoder_A == 1 and Encoder_B_old == 0) or (Encoder_A == 0 and Encoder_B_old == 1): # this will be clockwise rotation counts += 1 print 'Encoder count is %s' %counts print 'AB is %s %s' % (Encoder_A, Encoder_B) elif (Encoder_A == 1 and Encoder_B_old == 1) or (Encoder_A == 0 and Encoder_B_old == 0): # this will be counter-clockwise rotation counts -= 1 print 'Encoder count is %s' %counts print 'AB is %s %s' % (Encoder_A, Encoder_B) else: #this will be an error as well error += 1 print 'Error count is %s' %error Encoder_A_old = Encoder_A # store the current encoder values as old values to be used as comparison in the next loop Encoder_B_old = Encoder_B # Initialize the interrupts - these trigger on the both the rising and falling GPIO.add_event_detect('P8_7', GPIO.BOTH, callback = encodercount) # Encoder A GPIO.add_event_detect('P8_8', GPIO.BOTH, callback = encodercount) # Encoder B # This is the part of the code which runs normally in the background while True: time.sleep(1)

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• Prototyping Qt/C++ in Python

  - by tstenner

  I want to write a C++ application with Qt, but build a prototype first using Python and then gradually replace the Python code with C++. Is this the right approach, and what tools (bindings, binding generators, IDE) should I use? Ideally, everything should be available in the Ubuntu repositories so I wouldn't have to worry about incompatible or old versions and have everything set up with a simple aptitude install. Is there any comprehensive documentation about this process or do I have to learn every single component, and if yes, which ones? Right now I have multiple choices to make: Qt Creator, because of the nice auto completion and Qt integration. Eclipse, as it offers support for both C++ and Python. Eric (haven't used it yet) Vim PySide as it's working with CMake and Boost.Python, so theoretically it will make replacing python code easier. PyQt as it's more widely used (more support) and is available as a Debian package. Edit: As I will have to deploy the program to various computers, the C++-solution would require 1-5 files (the program and some library files if I'm linking it statically), using Python I'd have to build PyQt/PySide/SIP/whatever on every platform and explain how to install Python and everything else.

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• Extend legacy site with another server-side programming platform best practice

  - by Andrew Florko

  Company I work for have a site developed 6-8 years ago by a team that was enthusiastic enough to use their own private PHP-based CMS. I have to put dynamic data from one intranet company database on this site in one week: 2-3 pages. I contacted company site administrator and she showed me administrative part - CMS allows only to insert html blocks & manage site map (site is deployed on machine that is inside company & fully accessible & upgradeable). I'm not a PHP-guy & I don't want to dive into legacy hardly-who-ever-heard-about CMS engine I also don't want to contact developers team, 'cos I'm not sure they are still present and capable enough to extend this old days site and it'll take too much time anyway. I am about to deploy helper asp.net site on IIS with 2-3 pages required & refer helper site via iframe from present site. New pages will allow to download some dynamic content from present site also. Is it ok and what are the pitfalls with iframe approach?

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• Adding up fractions in PHP

  - by Gamemorize

  I would like to create a loop that keeps adding a set fraction, here in my example 1/3, and which later I can check against for matches with integer values. Obviously when php adds 1/3 + 1/3 + 1/3 the result is 0.9999999, so i thought I could use the occasional round to help me, but this isn't working either. The idea that I had would be that .333 + .333 becomes .666 and that if rounded that would become .667, then + .333 and the result is 1. However round only seems to work, for me, if the number of digits actually decreases. so round (0.666, 3) remains 0.666 <?php $denom = 3; $frac = 1/$denom; $frac = round($frac,3); $value = 0; $max =24; for($f = 1; $f <= $max; $f++){ echo "old value is now at ".$value.".<br/>"; $value = $value+$frac; echo "value is now at ".$value.".<br/>"; $value = round($value,3); echo "rounded value is now at ".$value.".<br/>"; $valueArray[$f] = $value; //and here for ease of testing.... if (($value==1)OR ($value==2)OR ($value==3)OR ($value==4)OR ($value==5)OR ($value==6)OR ($value==7)OR ($value==8)){ echo "match!<br/>"; }else{ echo "no match!<br/>"; } } ?> Am I going about this in a totally stupid way? Accuracy when the value is not an integer is not needed, just that it can == with integers.

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• How to draw shadows that don't suck?

  - by mystify

  A CAShapeLayer uses a CGPathRef to draw it's stuff. So I have a star path, and I want a smooth drop shadow with a radius of about 15 units. Probably there is some nice functionality in some new iPhone OS versions, but I need to do it myself for a old aged version of 3.0 (which most people still use). I tried to do some REALLY nasty stuff: I created a for-loop and sequentially created like 15 of those paths, transform-scaling them step by step to become bigger. Then assigning them to a new created CAShapeLayer and decreasing it's alpha a little bit on every iteration. Not only that this scaling is mathematically incorrect and sucks (it should happen relative to the outline!), the shadow is not rounded and looks really ugly. That's why nice soft shadows have a radius. The tips of a star shouldn't appear totally sharp after a shadow size of 15 units. They should be soft like cream. But in my ugly solution they're just as s harp as the star itself, since all I do is scale the star 15 times and decrease it's alpha 15 times. Ugly. I wonder how the big guys do it? If you had an arbitrary path, and that path must throw a shadow, how does the algorithm to do that work? Probably the path would have to be expanded like 30 times, point-by-point relative to the tangent of the outline away from the filled part, and just by 0.5 units to have a nice blending. Before I re-invent the wheel, maybe someone has a handy example or link?

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• How to provide i18n service for developer and end user

  - by user247245

  Many android applications have quite poor i18n-support, and for an understandable reason, as it adds much work for the developer. From a both intuitive and cultural point of view it would be a good thing if end-users could translate the apps themself, and OTA share the translation, without reinstalling the app itself. In concept; as wikipedia, some add content easily, others only use what's there. It's of course important that the service is as easy as possible to use, both for app-developers, and people willing to transcribe. To keep it simple, this is the solution I'm concidering; Developer perspective: Developer uses a customized setContentView when open activities/layouts that will seach for thanslations of xml-entries. (below) The customized version is provided as a free downloadable library/class..., turning the i18n feature to more or less a one liner. User perspective: User downloads app without any translation As app launches, it checks locale running at phone, and will look for a translated xml-file at shared space in SD. If no or old transcribed xml (above), try to download new from internet-service (ansync). This is all done by library above, no need for intents. Translator perspective: Separate app to provide translations for any app using the i18n service above. (Could be just a webapp), with some form of QA on translators/input. QUESTION: Now, for this to work efficiently, it has to be AeasyAP for the developer to even bother, and the most fluent solution would be a customized version of setContentView, that simply loads the translated values from external xml, instead of the ones in the apk. Is this possible at all, and if not, what's your suggested solutions? (And of course, Happy New Year, feliz ano novo, blwyddyn newydd dda, Gott Nytt År, kontan ane nouvo, szczesliwego nowego roku ...) Regards, /T

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• How should approach allowing users to create notes with revisions?

  - by Magicked

  I'm working on a Rails project where I want to allow users to create individual notes, which are really just text fields at this time. With each note, the user can edit what they have previously written, but the old version is kept in a revision table. I'm trying to figure out the best way to approach this. My initial thoughts are to have the following relationships: class User < ActiveRecord::Base has_many :notes end class Note < ActiveRecord::Base has_many :note_revisions belongs_to :user end class NoteRevision < ActiveRecord::Base belongs_to :note_revision end The Note model will only contain a timestamp of when the note was first created. The NoteRevision model will contain the text, as well as a timestamp for each revision. This way, every time a new revision is made, a new entry is created into the NoteRevision table which is tracked through the Note table. Hopefully this makes sense! First, does this look like a good way to do this? If so, I'm having trouble figuring out how the controller and view will present this information in one form. Are there any good tutorials or has someone seen anything similar that can point me in the right direction? Thanks in advance!

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• How do I insert null fields with Perl's DBD::Pg?

  - by User1

  I have a Perl script inserting data into Postgres according to a pipe delimited text file. Sometimes, a field is null (as expected). However, Perl makes this field into an empty string and the Postgres insert statement fails. Here's a snippet of code: use DBI; #Connect to the database. $dbh=DBI-connect('dbi:Pg:dbname=mydb','mydb','mydb',{AutoCommit=1,RaiseError=1,PrintError=1}); #Prepare an insert. $sth=$dbh-prepare("INSERT INTO mytable (field0,field1) SELECT ?,?"); while (<){ #Remove the whitespace chomp; #Parse the fields. @field=split(/\|/,$_); print "$_\n"; #Do the insert. $sth-execute($field[0],$field[1]); } And if the input is: a|1 b| c|3 EDIT: Use this input instead. a|1|x b||x c|3|x It will fail at b|. DBD::Pg::st execute failed: ERROR: invalid input syntax for integer: "" I just want it to insert a null on field1 instead. Any ideas? EDIT: I simplified the input at the last minute. The old input actually made it work for some reason. So now I changed the input to something that will make the program fail. Also note that field1 is a nullable integer datatype.

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• How expensive is a context switch? Is it better to implement a manual task switch than to rely on OS

  - by Vilx-

  The title says it all. Imagine I have two (three, four, whatever) tasks that have to run in parallel. Now, the easy way to do this would be to create separate threads and forget about it. But on a plain old single-core CPU that would mean a lot of context switching - and we all know that context switching is big, bad, slow, and generally simply Evil. It should be avoided, right? On that note, if I'm writing the software from ground up anyway, I could go the extra mile and implement my own task-switching. Split each task in parts, save the state inbetween, and then switch among them within a single thread. Or, if I detect that there are multiple CPU cores, I could just give each task to a separate thread and all would be well. The second solution does have the advantage of adapting to the number of available CPU cores, but will the manual task-switch really be faster than the one in the OS core? Especially if I'm trying to make the whole thing generic with a TaskManager and an ITask, etc?

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• Bing search API and Azure

  - by Gapton

  I am trying to programatically perform a search on Microsoft Bing search engine. Here is my understanding: There was a Bing Search API 2.0 , which will be replaced soon (1st Aug 2012) The new API is known as Windows Azure Marketplace. You use different URL for the two. In the old API (Bing Search API 2.0), you specify a key (Application ID) in the URL, and such key will be used to authenticate the request. As long as you have the key as a parameter in the URL, you can obtain the results. In the new API (Windows Azure Marketplace), you do NOT include the key (Account Key) in the URL. Instead, you put in a query URL, then the server will ask for your credentials. When using a browser, there will be a pop-up asking for a/c name and password. Instruction was to leave the account name blank and insert your key in the password field. Okay, I have done all that and I can see a JSON-formatted results of my search on my browser page. How do I do this programmatically in PHP? I tried searching for the documentation and sample code from Microsoft MSDN library, but I was either searching in the wrong place, or there are extremely limited resources in there. Would anyone be able to tell me how do you do the "enter the key in the password field in the pop-up" part in PHP please? Thanks alot in advance.

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• Why isn't our c# graphics code working any more?

  - by Jared

  Here's the situation: We have some generic graphics code that we use for one of our projects. After doing some clean-up of the code, it seems like something isn't working anymore (The graphics output looks completely wrong). I ran a diff against the last version of the code that gave the correct output, and it looks like we changed one of our functions as follows: static public Rectangle FitRectangleOld(Rectangle rect, Size targetSize) { if (rect.Width <= 0 || rect.Height <= 0) { rect.Width = targetSize.Width; rect.Height = targetSize.Height; } else if (targetSize.Width * rect.Height > rect.Width * targetSize.Height) { rect.Width = rect.Width * targetSize.Height / rect.Height; rect.Height = targetSize.Height; } else { rect.Height = rect.Height * targetSize.Width / rect.Width; rect.Width = targetSize.Width; } return rect; } to static public Rectangle FitRectangle(Rectangle rect, Size targetSize) { if (rect.Width <= 0 || rect.Height <= 0) { rect.Width = targetSize.Width; rect.Height = targetSize.Height; } else if (targetSize.Width * rect.Height > rect.Width * targetSize.Height) { rect.Width *= targetSize.Height / rect.Height; rect.Height = targetSize.Height; } else { rect.Height *= targetSize.Width / rect.Width; rect.Width = targetSize.Width; } return rect; } All of our unit tests are all passing, and nothing in the code has changed except for some syntactic shortcuts. But like I said, the output is wrong. We'll probably just revert back to the old code, but I'm curious if anyone has any idea what's going on here. Thanks.

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• How to face observable object containing an observable field

  - by iseek

  Hello, I need a hint concerning MVC and Observer-Pattern. For example a model contains the classes "Address" and "Person". The Address class contains the fields street:String, zipcode:String, location:String. Whereas the Person class contains the fields name:String, firstName:String, address:Address. My approach so far looks something like this: Both, Address and Person are observable. If one of their setters is being called, I validate whether the current value and new value differ. Only in this case an update event is fired. The event contains the source, the name of the changed field, the old and the new value. The class for the view contains text fields to display and edit the information of a person: name, firstname, street, zipcode, location. It knows the Person model and is an subscribed observer for the person. So it gets the update events from the person object. My questions concerns the address field from type Address in the person class, since an address is observable on its own. If the view gets an update event from person when a new address has been set, I can update all of the address related fields in the view. But what if a field of the address changes? Should the view also register for update events from the address? Any hints about common design approaches would be appreciated. Greetings.

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• How can I concisely copy multiple SQL rows, with minor modifications?

  - by Steve Jessop

  I'm copying a subset of some data, so that the copy will be independently modifiable in future. One of my SQL statements looks something like this (I've changed table and column names): INSERT Product( ProductRangeID, Name, Weight, Price, Color, And, So, On ) SELECT @newrangeid AS ProductRangeID, Name, Weight, Price, Color, And, So, On FROM Product WHERE ProductRangeID = @oldrangeid and Color = 'Blue' That is, we're launching a new product range which initially just consists of all the blue items in some specified current range, under new SKUs. In future we may change the "blue-range" versions of the products independently of the old ones. I'm pretty new at SQL: is there something clever I should do to avoid listing all those columns, or at least avoid listing them twice? I can live with the current code, but I'd rather not have to come back and modify it if new columns are added to Product. In its current form it would just silently fail to copy the new column if I forget to do that, which should show up in testing but isn't great. I am copying every column except for the ProductRangeID (which I modify), the ProductID (incrementing primary key) and two DateCreated and timestamp columns (which take their auto-generated values for the new row). Btw, I suspect I should probably have a separate join table between ProductID and ProductRangeID. I didn't define the tables. This is in a T-SQL stored procedure on SQL Server 2008, if that makes any difference.

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• Book/topic recommendations for a programmer returning to programming.

  - by Jason Tan

  I used to be a developer in Java, PHP, perl and C/C++ (the C++ bit badly - the others not too badly, I hope). This was back in the Java 1.3/1.4 days. We used raw JDBC, swing, servlets, JSP and ant (sometimes even make). Eclipse was new. Then I joined a deployment team and became a deployment engineer and then after the deployment engineer work became a full time sys admin.You get the idea - my experience is a generation or two old in programming terms - maybe older. I'm interested in getting back into Java and perhaps Ruby development, but feel I will be waaaaay behind the technological 8 ball. Can you folks suggest some books (or sites) that would be worth reading to catch up with the last 5-10 years of the development world. I.e. what should I read to try and catch up with where development is now? I see lots of stuff on the web, but what are people in the fabled "real world" using? (are lots of people being SOA based apps? Are they using XP methodology) The sorts of things I'm interested in finding out about/catching up on are: Methodologies Design patterns APIs/Frameworks/Technologies Other stuff you deem current/interesting/relevant. So if you have any thoughts or can recommend any books (especially new classics - you know the 's equivalent to K&R C or "The mythical man month"). Thanks for any thoughts you might share.

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• Why does this code sample produce a memory leak?

  - by citronas

  In the university we were given the following code sample and we were being told, that there is a memory leak when running this code. The sample should demonstrate that this is a situation where the garbage collector can't work. As far as my object oriented programming goes, the only codeline able to create a memory leak would be items=Arrays.copyOf(items,2 * size+1); The documentation says, that the elements are copied. Does that mean the reference is copied (and therefore another entry on the heap is created) or the object itself is being copied? As far as I know, Object and therefore Object[] are implemented as a reference type. So assigning a new value to 'items' would allow the garbage collector to find that the old 'item' is no longer referenced and can therefore be collected. In my eyes, this the codesample does not produce a memory leak. Could somebody prove me wrong? =) import java.util.Arrays; public class Foo { private Object[] items; private int size=0; private static final int ISIZE=10; public Foo() { items= new Object[ISIZE]; } public void push(final Object o){ checkSize(); items[size++]=o; } public Object pop(){ if (size==0) throw new ///... return items[--size]; } private void checkSize(){ if (items.length==size){ items=Arrays.copyOf(items,2 * size+1); } } }

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• What are the best tricks for learning how to -think- in Objective-C?

  - by Braintapper

  Before I get flamed out for not checking previous questions, I have read most of the tutorials, and have Hillegass' book, as well as O'Reilly's book on it. I'm not asking for tips on Cocoa or what IDE to use. Where my issue lies - my 'mental muscle memory' is making it hard for me to read Objective-C code. I have no problems at all reading Java and C code and understanding what's going on. Maybe I'm getting to old to learn a new syntax, but it's a struggle shifting mental gears and looking at Objective-C code and just "getting it" (I thought it might be an isolated case, but I have other friends who are seasoned devs who have said the same thing). Are there any tricks that any non-Objective-C programmers who now know Objective-C used to help process the syntactical differences when learning it? For some reason, I get dyslexic when reading Objective-C code. Maybe I'm not meant to be able to learn it (and that's ok too). I was hoping/wondering if there might be others who have had the same experience.

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• Can someone recommend a good tutorial on MySQL indexes, specifically when used in an order by clause

  - by Philip Brocoum

  I could try to post and explain the exact query I'm trying to run, but I'm going by the old adage of, "give a man a fish and he'll eat for a day, teach a man to fish and he'll eat for the rest of his life." SQL optimization seems to be very query-specific, and even if you could solve this one particular query for me, I'm going to have to write many more queries in the future, and I'd like to be educated on how indexes work in general. Still, here's a quick description of my current problem. I have a query that joins three tables and runs in 0.2 seconds flat. Awesome. I add an "order by" clause and it runs in 4 minutes and 30 seconds. Sucky. I denormalize one table so there is one fewer join, add indexes everywhere, and now the query runs in... 20 minutes. What the hell? Finally, I don't use a join at all, but rather a subquery with "where id in (...) order by" and now it runs in 1.5 seconds. Pretty decent. What in God's name is going on? I feel like if I actually understood what indexes were doing I could write some really good SQL. Anybody know some good tutorials? Thanks!

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• MySQL: SELECT highest column value when WHERE finds similar entries

  - by Ike

  My question is comparable to this one, but not quite the same. I have a database with a huge amount of books, with different editions of some of the same book titles. I'm looking for an SQL statement giving me the highest edition number of each of the titles I'm selecting with a WHERE clause (to find specific book series). Here's what the table looks like: |id|title |edition|year| |--|-------------------------|-------|----| |01|Serie One Title One |1 |2007| |02|Serie One Title One |2 |2008| |03|Serie One Title One |3 |2009| |04|Serie One Title Two |1 |2001| |05|Serie One Title Three |1 |2008| |06|Serie One Title Three |2 |2009| |07|Serie One Title Three |3 |2010| |08|Serie One Title Three |4 |2011| |--|-------------------------|-------|----| The result I'm looking for is this: |id|title |edition|year| |--|-------------------------|-------|----| |03|Serie One Title One |3 |2009| |04|Serie One Title Two |1 |2001| |08|Serie One Title Three |4 |2011| |--|-------------------------|-------|----| The closest I got was using this statement: select id, title, max(edition), max(year) from books where title like "serie one%" group by name; but it returns the highest edition and year and includes the first id it finds: |--|-----------------------|-------|----| |01|Serie One Title One |3 |2009| |04|Serie One Title Two |1 |2001| |05|Serie One Title Three |4 |2011| |--|-----------------------|-------|----| This fancy join also comes close, but doesn't give the right result: select b.id, b.title, b.edition, b.year from books b inner join (select name, max(edition) as maxedition from books group by title) g on b.edition = g.maxedition where b.title like "serie one%" group by title; Using this I'm getting unique titles, but mostly old editions.

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