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• How can I remove an "ALMOST" Duplicate using LINQ? ( OR SQL? )

  - by Atomiton

  This should be and easy one for the LINQ gurus out there. I'm doing a complex Query using UNIONS and CONTAINSTABLE in my database to return ranked results to my application. I'm getting duplicates in my returned data. This is expected. I'm using CONTAINSTABLE and CONTAINS to get all the results I need. CONTAINSTABLE is ranked by SQL and CONTAINS (which is run only on the Keywords field ) is hard-code-ranked by me. ( Sorry if that doesn't make sense ) Anyway, because the tuples aren't identical ( their rank is different ) a duplicate is returned. I figure the best way to deal with this is use LINQ. I know I'll be using the Distinct() extension method, but do I have to implement the IEqualityComparer interface? I'm a little fuzzy on how to do this. For argument's sake, say my resultset is structured like this class: class Content { ContentID int //KEY Rank int Description String } If I have a List<Content> how would I write the Distinct() method to exclude Rank? Ideally I'd like to keep the Content's highest Rank. SO, if one Content's RAnk is 112 and the other is 76. I'd like to keep the 112 rank. Hopefully I've given enough information.

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• Techniques for sharing a value among classes in a program

  - by Kenneth Cochran

  I'm using Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData) + "\MyProgram" As the path to store several files used by my program. I'd like to avoid pasting the same snippet of code all over the my applcation. I need to ensure that: The path cannot be accidentally changed once its been set The classes that need it have access to it. I've considered: Making it a singleton Using constructor dependency injection Using property dependency injection Using AOP to create the path where its needed. Each has pros and cons. The singleton is everyone's favorite whipping boy. I'm not opposed to using one but there are valid reasons to avoid it if possible. I'm already heavily using constructor injection through Castle Windsor. But this is a path string and Windsor doesn't handle system type dependencies very gracefully. I could always wrap it in a class but that seems like overkill for something as simple as a passing around a string value. In any case this route would add yet another constructor argument to each class where it is used. The problem I see with property injection in this case is that there is a large amount of indirection from the where the value is set to where it is needed. I would need a very long line of middlemen to reach all the places where its used. AOP looks promising and I'm planning on using AOP for logging anyway so this at least sounds like a simple solution. Is there any other options I haven't considered? Am I off base with my evaluation of the options I have considered?

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• Why am I getting a segmentation fault?

  - by Phenom

  If I pass a value greater than 100 as the second argument to BinaryInsertionSort, I get a segmentation fault. int BinarySearch (int a[], int low, int high, int key) { int mid; if (low == high) return low; mid = low + ((high - low) / 2); if (key > a[mid]) return BinarySearch (a, mid + 1, high, key); else if (key < a[mid]) return BinarySearch (a, low, mid, key); return mid; } void BinaryInsertionSort (int a[], int n) { int ins, i, j; int tmp; for (i = 1; i < n; i++) { ins = BinarySearch (a, 0, i, a[i]); if (ins < i) { tmp = a[i]; memmove (a + ins + 1, a + ins, sizeof (int) * (i - ins)); a[ins] = tmp; } } }

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• Splitting MS Access Database - Front End Part Location

  - by kristof

  One of the best practices as specified by Microsoft for Access Development is splitting Access application into 2 parts; Front End that hold all the object except tables and the Back End that holds the tables. The msdn page links there to the article Splitting Microsoft Access Databases to Improve Performance and Simplify Maintainability that describes the process in details. It is recommended that in multi user environment the Back End is stored on the server/shared folder while the Front End is distributed to each user. That implies that each time there are any changes made to the front end they need to be deployed to every user machine. My question is: Assuming that the users themselves do not have rights to modify the Front End part of the application what would be the drawbacks/dangers of leaving this on the server as well next to the Back End copy? I can see the performance issues here, but are there any dangers here like possible corruptions etc? Thank you EDIT Just to clarify, the scenario specified in question assumes one Front End stored on the server and shared by users. I understand that the recommendation is to have FE deployed to each user machine, but my question is more about what are the dangers if that is not done. E.g. when you are given an existing solution that uses the approach of both FE and BE on the server. Assuming the the performance is acceptable and the customer is reluctant to change the approach would you still push the change? And why exactly? For example the danger of possible data corruption would definitely be the strong enough argument, but is that the case? It is a part of follow up of my previous question From SQL Server to MS Access 2007

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• How can I test for an empty Breeze predicate?

  - by Megan

  I'm using Breeze to filter data requested on the client. My code looks a little like this: Client - Creating Filter Predicate var predicates = []; var criteriaPredicate = null; $.each(selectedFilterCriteria(), function (index, item) { criteriaPredicate = (index == 0) ? breeze.Predicate.create('criteriaId', breeze.FilterQueryOp.Equals, item) : criteriaPredicate.or('criteriaId', breeze.FilterQueryOp.Equals, item); if (breeze.Predicate.isPredicate(criteriaPredicate)) { predicates.push(criteriaPredicate); } // Repeat for X Filter Criteria var filter = breeze.Predicate.and(predicates); return context.getAll(filter, data); Client - Context Query function getAll(predicate, dataObservable) { var query = breeze.EntityQuery.from('Data'); if (breeze.Predicate.isPredicate(predicate)) { query = query.where(predicate); } return manager.executeQuery(query).then(success).fail(failure); } Issue I'm having an issue with the request because, if there are no filters set, I apply an "empty" predicate (due to the var filter = breeze.Predicate.and([]) line) resulting in a request like http://mysite/api/app/Data?$filter=. The request is an invalid OData query since the value of the $filter argument cannot be empty. Is there a good way for me to check for an empty predicate? I know I can refactor my client code to not use a predicate unless there is at least one filterable item, but I thought I would check first to see if I overlooked some property or method on the Breeze Predicate.

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• Why not use tables for layout in HTML?

  - by Bno

  It seems to be the general opinion that tables should not be used for layout in HTML. Why? I have never (or rarely to be honest) seen good arguments for this. The usual answers are: It's good to separate content from layoutBut this is a fallacious argument; Cliche Thinking. I guess it's true that using the table element for layout has little to do with tabular data. So what? Does my boss care? Do my users care?Perhaps me or my fellow developers who have to maintain a web page care... Is a table less maintainable? I think using a table is easier than using divs and CSS.By the way... why is using a div or a span good separation of content from layout and a table not? Getting a good layout with only divs often requires a lot of nested divs. Readability of the codeI think it's the other way around. Most people understand html, few understand CSS. It's better for SEO not to use tablesWhy? Can anybody show some evidence that it is? Or a statement from Google that tables are discouraged from an SEO perspective? Tables are slower.An extra tbody element has to be inserted. This is peanuts for modern web browsers. Show me some benchmarks where the use of a table significantly slows down a page. A layout overhaul is easier without tables, see css Zen Garden.Most web sites that need an upgrade need new content (html) as well. Scenarios where a new version of a web site only needs a new CSS file are not very likely. Zen Garden is a nice web site, but a bit theoretical. Not to mention its misuse of CSS. I am really interested in good arguments to use divs + CSS instead of tables.

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• What's correct way to remove a boost::shared_ptr from a list?

  - by Catskul

  I have a std::list of boost::shared_ptr<T> and I want to remove an item from it but I only have a pointer of type T* which matches one of the items in the list. However I cant use myList.remove( tPtr ) I'm guessing because shared_ptr does not implement == for its template argument type. My immediate thought was to try myList.remove( shared_ptr<T>(tPtr) ) which is syntactically correct but it will crash from a double delete since the temporary shared_ptr has a separate use_count. std::list< boost::shared_ptr<T> > myList; T* tThisPtr = new T(); // This is wrong; only done for example code. // stand-in for actual code in T using // T's actual "this" pointer from within T { boost::shared_ptr<T> toAdd( tThisPtr ); // typically would be new T() myList.push_back( toAdd ); } { //T has pointer to myList so that upon a certain action, // it will remove itself romt the list //myList.remove( tThisPtr); //doesn't compile myList.remove( boost::shared_ptr<T>(tThisPtr) ); // compiles, but causes // double delete } The only options I see remaining are to use std::find with a custom compare, or to loop through the list brute force and find it myself, but it seems there should be a better way. Am I missing something obvious, or is this just too non-standard a use to be doing a remove the clean/normal way?

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• Create dynamic factory method in PHP (< 5.3)

  - by fireeyedboy

  How would one typically create a dynamic factory method in PHP? By dynamic factory method, I mean a factory method that will autodiscover what objects there are to create, based on some aspect of the given argument. Preferably without registering them first with the factory either. I'm OK with having the possible objects be placed in one common place (a directory) though. I want to avoid your typical switch statement in the factory method, such as this: public static function factory( $someObject ) { $className = get_class( $someObject ); switch( $className ) { case 'Foo': return new FooRelatedObject(); break; case 'Bar': return new BarRelatedObject(); break; // etc... } } My specific case deals with the factory creating a voting repository based on the item to vote for. The items all implement a Voteable interface. Something like this: Default_User implements Voteable ... Default_Comment implements Voteable ... Default_Event implements Voteable ... Default_VoteRepositoryFactory { public static function factory( Voteable $item ) { // autodiscover what type of repository this item needs // for instance, Default_User needs a Default_VoteRepository_User // etc... return new Default_VoteRepository_OfSomeType(); } } I want to be able to drop in new Voteable items and Vote repositories for these items, without touching the implementation of the factory.

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• Rails ajax jquery problem

  - by user283179

  Ok I have this problem I'm trying to use Jquery to load a partial in replace of a listed object. loadshow: $(function() { $(".style_image_<%= style.id %> a").click(function() { $(".style_image_<%= style.id %>").html("loading... ") $(".style_image_<%= style.id %>").html("<%= escape_javascript(render("show")) %>") $.get(this.href, null, null, "html"); return false; }); }); _show.html.erb: <%=link_to image_tag(style.cover.pic.url(:normal)), style %> I'm getting this error: missing ) after argument list [Break on this error] $(".style_image_<%= style.id %>").htm...scape_javascript(render("show")) %>")\n There is two problems with my code here the first is the click function is not targeting the .style_image_<%= style.id % .... i.e (.style_image_42) if I replace the css target with 42 instead of _style.id the click target works; why is this? And with or without this change the _show partial is not render and the above error is given. Not really that good with Javascript any help would be great! P.s. The effect I really want is like one of those super cool cargo themes: http://cargocollective.com/publikspace Thanks Dan!

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• Plotting andrews curves of subsets of a data frame on the same plot

  - by user2976477

  I have a data frame of 12 columns and I want to plot andrews curves in R of this data, basing the color of the curves on the 12th columns. Below are a few samples from the data (sorry the columns are not aligned with the numbers) Teacher_explaining Teacher_enthusiastic Teacher_material_interesting Material_stimulating Material_useful Clear_marking Marking_fair Feedback_prompt Feedback_clarifies Detailed_comments Notes Year 80 80 80 80 85 85 80 80 80 80 70 3 70 60 30 40 70 60 30 40 70 0 30 3 100 90 90 80 80 100 100 90 100 100 100 MSc 85 85 85 90 90 70 90 50 70 80 100 MSc 90 50 90 90 90 70 100 50 80 100 100 4 100 80 80 75 90 80 80 50 80 80 90 3 From this data I tried to plot andrews curves using the code below: install.packages("andrews") library(andrews) col <- as.numeric(factor(course[,12])) andrews(course[,1:12], clr = 12) However, the 12th column has three groups (3 types of responses) and I want to group two of them and then plot the andrews curve of the data, without editing my data frame in Excel. x <- subset(course, Year == "MSc" & "4") y <- subset(course, Year == "3") I tried the above code, but my argument for x don't work. "MSc", "3" and "4" are the groups in the 12th column, and I want to group MSc and 4 so that their Andrews curves have the same color. If you have any idea how to do this, please let me know.

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• python-iptables: Cryptic error when allowing incoming TCP traffic on port 1234

  - by Lucas Kauffman

  I wanted to write an iptables script in Python. Rather than calling iptables itself I wanted to use the python-iptables package. However I'm having a hard time getting some basic rules setup. I wanted to use the filter chain to accept incoming TCP traffic on port 1234. So I wrote this: import iptc chain = iptc.Chain(iptc.TABLE_FILTER,"INPUT") rule = iptc.Rule() target = iptc.Target(rule,"ACCEPT") match = iptc.Match(rule,'tcp') match.dport='1234' rule.add_match(match) rule.target = target chain.insert_rule(rule) However when I run this I get this thrown back at me: Traceback (most recent call last): File "testing.py", line 9, in <module> chain.insert_rule(rule) File "/usr/local/lib/python2.6/dist-packages/iptc/__init__.py", line 1133, in insert_rule self.table.insert_entry(self.name, rbuf, position) File "/usr/local/lib/python2.6/dist-packages/iptc/__init__.py", line 1166, in new obj.refresh() File "/usr/local/lib/python2.6/dist-packages/iptc/__init__.py", line 1230, in refresh self._free() File "/usr/local/lib/python2.6/dist-packages/iptc/__init__.py", line 1224, in _free self.commit() File "/usr/local/lib/python2.6/dist-packages/iptc/__init__.py", line 1219, in commit raise IPTCError("can't commit: %s" % (self.strerror())) iptc.IPTCError: can't commit: Invalid argument Exception AttributeError: "'NoneType' object has no attribute 'get_errno'" in <bound method Table.__del__ of <iptc.Table object at 0x7fcad56cc550>> ignored Does anyone have experience with python-iptables that could enlighten on what I did wrong?

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• Can I recover lost commits in a SVN repository using a local tracking git-svn branch?

  - by Ian Stevens

  A SVN repo I use git-svn to track was recently corrupted and a backup was recovered. However, a week's worth of commits were lost in the recovery. Is it possible to recover those lost commits using git-svn dcommit on my local git repo? Is it sufficient to run git-svn dcommit with the SHA1 of the last recovered commit in SVN? eg. > svn info http://tracked-svn/trunk | sed -n "s/Revision: //p" 252 > git log --grep="git-svn-id:.*@252" --format=oneline | cut -f1 -d" " 55bb5c9cbb5fe11a90ec2e9e1e0c7c502908cf9a > git svn dcommit 55bb5c9cbb5fe11a90ec2e9e1e0c7c502908cf9a Or will the git-svn-id need to be stripped from the intended commits? I tried this using --dry-run but couldn't tell whether it would try to submit all commits: > git svn dcommit --verbose --dry-run 55bb5c9cbb5fe11a90ec2e9e1e0c7c502908cf9a Committing to http://tracked-svn/trunk ... dcommitted on a detached HEAD because you gave a revision argument. The rewritten commit is: 55bb5c9cbb5fe11a90ec2e9e1e0c7c502908cf9a Thanks for your help.

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• How to document an accessor/mutator method in phpDoc/javaDoc?

  - by nickf

  Given a function which behaves as either a mutator or accessor depending on the arguments passed to it, like this: // in PHP, you can pass any number of arguments to a function... function cache($cacheName) { $arguments = func_get_args(); if (count($arguments) >= 2) { // two arguments passed. MUTATOR. $value = $arguments[1]; // use the second as the value $this->cache[$cacheName] = $value; // *change* the stored value } else { // 1 argument passed, ACCESSOR return $this->cache[$cacheName]; // *get* the stored value } } cache('foo', 'bar'); // nothing returned cache('foo') // 'bar' returned How do you document this in PHPDoc or a similar automated documentation creator? I had originally just written it like this: /** * Blah blah blah, you can use this as both a mutator and an accessor: * As an accessor: * @param $cacheName name of the variable to GET * @return string the value... * * As a mutator: * @param $cacheName name of the variable to SET * @param $value the value to set * @return void */ However, when this is run through phpDoc, it complains because there are 2 return tags, and the first @param $cacheName description is overwritten by the second. Is there a way around this?

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• Adding custom methods to a subclassed NSManagedObject

  - by CJ

  I have a Core Data model where I have an entity A, which is an abstract. Entities B, C, and D inherit from entity A. There are several properties defined in entity A which are used by B, C, and D. I would like to leverage this inheritance in my model code. In addition to properties, I am wondering if I can add methods to entity A, which are implemented in it's sub-entities. For example: I add a method to the interface for entity A which returns a value and takes one argument I add implementations of this method to A, B, C, D Then, I call executeFetchRequest: to retrieve all instances of B I call the method on the objects retrieved, which should call the implementation of the method contained in B's implementation I have tried this, but when calling the method, I receive: [NSManagedObject methodName:]: unrecognized selector sent to instance I presume this is because the objects returned by executeFetchRequest: are proxy objects of some sort. Is there any way to leverage inheritance using subclassed NSManagedObjects? I would really like to be able to do this, otherwise my model code would be responsible for determining what type of NSManagedObject it's dealing with and perform special logic according to the type, which is undesirable. Any help is appreciated, thanks in advance.

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• Serial.begin(speed, config) not compiling for Leonardo Board

  - by forgemo

  I would like to configure my serial communication to have no parity, 1 start- and 2 stop-bits. The documentation for Serial.begin(speed, config) states: (...) An optional second argument configures the data, parity, and stop bits. The default is 8 data bits, no parity, one stop bit. The documentation also lists the possible configuration-values. According to my (limited) understanding, I need SERIAL_7N2 or SERIAL_8N2 to meet my requirements. (I'm not sure how the data-bits relate to the the 1-start-bit that I need.) However, I can't even compile because I have no idea how to supply that config value to the begin method. (I don't have much Arduino/C++ experience) I've tried in my code the following two variants: Serial.begin(9600, SERIAL_8N2); Serial.begin(9600, "SERIAL_8N2"); Am I missing something? Additional Information: Serial.begin(speed, config) has been introduced with the latest Arduino 1.0.2 IDE version. The code defining/implementing the begin methods can be found here. HardwareSerial.h HardwareSerial.cpp Edit: According to the replies from PeterJ and borges, the following variant is correct. Serial.begin(9600, SERIAL_8N2); However, it's still not working. I found that the compile error doesn't occur if I change the configured board from my Arduino Leonardo to Arduino uno. Therefore, it could be a bug occurring only with a subset of boards ... or maybe it's not supported?!

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• Umlaute from JSP-page are misinterpreted

  - by Karin

  I'm getting Input from a JSP page, that can contain Umlaute. (e.g. Ä,Ö,Ü,ä,ö,ü,ß). Whenever an Umlaut is entered in the Input field an incorrect value gets passed on. e.g. If an "ä" (UTF-8:U+00E4) gets entered in the input field, the String that is extracted from the argument is "ä" (UTF-8: U+00C3 and U+00A4) It seems to me as if the UTF-8 hex encoding (which is c3 a4 for an "ä") gets used for the conversion. How can I retrieved the correct value? Here are snippets from the current implementation The JSP-page passes the input value "pk" on to the processing logic: <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> ... <input type="text" name="<%=pk.toString()%>" value="<%=value%>" size="70"/> <button type="submit" title="Edit" value='Save' onclick="action.value='doSave';pk.value='<%=pk.toString()%>'"><img src="icons/run.png"/>Save</button> The value gets retrieved from args and converted to a string: UUID pk = UUID.fromString(args.get("pk")); //$NON-NLS-1$ String value = args.get(pk.toString()); Note: Umlaute that are saved in the Database get displayed correctly on the page.

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• algorithm || method to write prog

  - by fatai

  I am one of the computer science student. My wonder is everyone solve problem with different or same method, but actually I dont know whether they use method or I dont know whether there are such common method to approach problem. All teacher give us problem which in simple form sometimes, but they dont introduce any approach or method(s) so that we can first choose method then apply that one to problem , afterward find solution then write code. I have found one method when I failed the course, More accurately, When I counter problem in language , I will get more paper and then ; first, input/ output step ; my prog will take this / these there argument(s) and return namely X , ex : in c, input length is not known and at same type , so I must use pointer desired output is in form of package , so use structure second, execution part ; in that step , I am writing all step which are goes to final output ex : in python ; 1.) [ + , [- , 4 , [ * , 1 , 2 ]], 5] 2.) [ + , [- , 4 , 2 ],5 ] 3.) [ + , 2 , 5] 4.) 7 ==> return 7 third, I will write test code ex : in c++ input : append 3 4 5 6 vector_x remove 0 1 desired output vector_x holds : 5 6 But now, I wonder other method ; used to construct class :::: for c++ , python, java used to communicate classes / computers used for solving embedded system problem ::::: for c Why I wonder , because I learn if you dont costruct algorithm on paper, you may achieve your goal. Like no money no lunch , I can say no algorithm no prog therefore , feel free when you write your own method , a way which is introduced by someone else but you are using and you find it is so efficient

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• With PascalMock how do I mock a method with an untyped out parameter and an open array parameter?

  - by Oliver Giesen

  I'm currently in the process of getting started with unit testing and mocking for good and I stumbled over the following method that I can't seem to fabricate a working mock implementation for: function GetInstance(const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID = CID_DEFAULT): Boolean; (TImplContextID is just an alias for Integer) I thought it would have to look something like this: function TImplementationProviderMock.GetInstance( const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID): Boolean; begin Result := AddCall('GetInstance') .WithParams([@AIID, AContextID]) .ReturnsOutParams([AInstance]) .ReturnValue; end; But the compiler complains about the .ReturnsOutParams([AInstance]) saying "Bad argument type in variable type array constructor.". Also I haven't found a way to specify the open array parameter AArgs at all. Also, is using the @-notation for the TGUID-typed parameter the right way to go? Is it possible to mock this method with the current version of PascalMock at all?

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• Help passing reference to class subroutine in Perl.

  - by stephenmm

  I am trying to pass a routine to another subroutine within a Perl module. But when I pass the sub reference the passed in ref no longer has the object data. Maybe its not possible to do it this way. The line I have a question about is the "unless" lines below: sub get_flag_end { my $self = shift; return ( -e "$self->{file}" ); } sub wait_for_end { my $self = shift; my $timeout = shift; my $poll_interval = shift; # Is it even possible to pass the oject subroutine and retain the objects data? #unless ( $self->timeout( $timeout, $poll_interval, $self->get_flag_end ) ) { # does not work unless ( $self->timeout( $timeout, $poll_interval, \&get_flag_end ) ) { # call happens but members are empty die "!!!ERROR!!! Timed out while waiting for wait_for_end: timeout=$timeout, poll_interval=$poll_interval \n"; } } sub timeout { my $self = shift; my $timeout = shift; my $poll_interval = shift; my $test_condition = shift; until ($test_condition->() || $timeout <= 0) { $timeout -= $poll_interval; sleep $poll_interval; } return $timeout > 0; # condition was met before timeout } I know that I could change the "get_flag_end" routine to take the value as an argument to the subroutine but what if there was a bunch of stuff done in "get_flag_end" and I needed more members from the object. I simplified the code a bit to make it a little easier to follow.

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• What would cause native gem extensions on OS X to build but fail to load?

  - by goodmike

  I am having trouble with some of my rubygems, in particular those that use native extensions. I am on a MacBookPro, with Snow Leopard. I have XCode 3.2.1 installed, with gcc 4.2.1. Ruby 1.8.6, because I'm lazy and a scaredy cat and don't want to upgrade yet. Ruby is running in 32-bit mode. I built this ruby from scratch when my MBP ran OSX 10.4. When I require one of the affected gems in irb, I get a Load Error for the gem extension's bundle file. For example, here's nokogigi dissing me: > require 'rubygems' = true > require 'nokogiri' LoadError: Failed to load /usr/local/lib/ruby/gems/1.8/gems/nokogiri-1.4.1/lib/nokogiri/nokogiri.bundle This is also happening with the Postgres pg and MongoDB mongo gems. My first thought was that the extensions must not be building right. But gem install wasn't throwing any errors. So I reinstalled with the verbose flag, hoping to see some helpful warnings. I've put the output in a Pastie, and the only warning I see is a consistent one about "passing argument n of ‘foo’ with different width due to prototype." I suspect that this might be an issue from upgrading to Snow Leopard, but I'm a little surprised to experience it now, since I've updated my XCode. Could it stem from running Ruby in 1.8.6? I'm embarrassed that I don't know quite enough about my Mac and OSX to know where to look next, so any guidance, even just a pointer to some document I couldn't find via Google, would be most welcome. Michael

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• How does the overall view hierarchy change when using UIKit view manipulations?

  - by executor21

  I've been trying to figure out what happens in the view hierarchy when methods like pushViewController:animated, presentModalViewController:animated, and tab switches in UITabBarViewController are used, as well as UIAlertView and UIActionSheet. (Side note: I'm doing this because I need to know whether a specific UIView of my creation is visible on screen when I do not know anything about how it or its superview may have been added to the view hierarchy. If someone knows a good way to determine this, I'd welcome the knowledge.) To figure it out, I've been logging out the hierarchy of [[UIApplication sharedApplication] keyWindow] subviews in different circumstances. Is the following correct: When a new viewController is pushed onto the stack of a UINavigationController, the old viewController's view is no longer in the view hierarchy. That is, only the top view controller's view is a subview of UINavigationController's view (according to logs, it's actually several private classes such as UILayoutContainerView). Are the views of view controllers below the top controller of the stack actually removed from the window? A very similar thing happens when a new viewController is presented via presentModalViewController:animated. The new viewController's view is the only subview of the kew window. Is this correct? The easiest thing to understand: a UIAlertView creates its own window and makes it key. The strangest thing I encountered: a UIActionSheet is shown via showInView: method, the actionSheet isn't in the view hierarchy at all. It's not a subview of the view passed as an argument to showInView:, it isn't added as a subview of the key window, and it doesn't create its own window. How does it appear, then? I haven't tried this yet, so I'd like to know what happens in the keyWindow hierarchy when tabs in a UITabBarController are switched. Is the view of the selected UIViewController moved to the top, or does it work like with pushViewController:animated and presentModalViewController:animated, where only the displayed view is in the window hierarchy?

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• Reading email address from contacts fails with weird memory issue

  - by CapsicumDreams

  Hi all, I'm stumped. I'm trying to get a list of all the email address a person has. I'm using the ABPeoplePickerNavigationController to select the person, which all seems fine. I'm setting my ABRecordRef personDealingWith; from the person argument to - (BOOL)peoplePickerNavigationController:(ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)person property:(ABPropertyID)property identifier:(ABMultiValueIdentifier)identifier { and everything seems fine up till this point. The first time the following code executes, all is well. When subsequently run, I can get issues. First, the code: // following line seems to make the difference (issue 1) // NSLog(@"%d", ABMultiValueGetCount(ABRecordCopyValue(personDealingWith, kABPersonEmailProperty))); // construct array of emails ABMultiValueRef multi = ABRecordCopyValue(personDealingWith, kABPersonEmailProperty); CFIndex emailCount = ABMultiValueGetCount(multi); if (emailCount 0) { // collect all emails in array for (CFIndex i = 0; i < emailCount; i++) { CFStringRef emailRef = ABMultiValueCopyValueAtIndex(multi, i); [emailArray addObject:(NSString *)emailRef]; CFRelease(emailRef); } } // following line also matters (issue 2) CFRelease(multi); If compiled as written, the are no errors or static analysis problems. This crashes with a *** -[Not A Type retain]: message sent to deallocated instance 0x4e9dc60 error. But wait, there's more! I can fix it in either of two ways. Firstly, I can uncomment the NSLog at the top of the function. I get a leak from the NSLog's ABRecordCopyValue every time through, but the code seems to run fine. Also, I can comment out the CFRelease(multi); at the end, which does exactly the same thing. Static compilation errors, but running code. So without a leak, this function crashes. To prevent a crash, I need to haemorrhage memory. Neither is a great solution. Can anyone point out what's going on?

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• What's the Matlab equivalent of NULL, when it's calling COM/ActiveX methods?

  - by David M

  Hi, I maintain a program which can be automated via COM. Generally customers use VBS to do their scripting, but we have a couple of customers who use Matlab's ActiveX support and are having trouble calling COM object methods with a NULL parameter. They've asked how they do this in Matlab - and I've been scouring Mathworks' COM/ActiveX documentation for a day or so now and can't figure it out. Their example code might look something like this: function do_something() OurAppInstance = actxserver('Foo.Application'); OurAppInstance.Method('Hello', NULL) end where NULL is where in another language, we'd write NULL or nil or Nothing, or, of course, pass in an object. The problem is this is optional (and these are implemented as optional parameters in most, but not all, cases) - these methods expect to get NULL quite often. They tell me they've tried [] (which from my reading seemed the most likely) as well as '', Nothing, 'Nothing', None, Null, and 0. I have no idea how many of those are even valid Matlab keywords - certainly none work in this case. Can anyone help? What's Matlab's syntax for a null pointer / object for use as a COM method parameter? Update: Thanks for all the replies so far! Unfortunately, none of the answers seem to work, not even libpointer. The error is the same in all cases: Error: Type mismatch, argument 2 This parameter in the COM type library is described in RIDL as: HRESULT _stdcall OurMethod([in] BSTR strParamOne, [in, optional] OurCoClass* oParamTwo, [out, retval] VARIANT_BOOL* bResult); The coclass in question implements a single interface descending from IDispatch.

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• Base class deleted before subclass during python __del__ processing

  - by Oddthinking

  Context I am aware that if I ask a question about Python destructors, the standard argument will be to use contexts instead. Let me start by explaining why I am not doing that. I am writing a subclass to logging.Handler. When an instance is closed, it posts a sentinel value to a Queue.Queue. If it doesn't, a second thread will be left running forever, waiting for Queue.Queue.get() to complete. I am writing this with other developers in mind, so I don't want a failure to call close() on a handler object to cause the program to hang. Therefore, I am adding a check in __del__() to ensure the object was closed properly. I understand circular references may cause it to fail in some circumstances. There's not a lot I can do about that. Problem Here is some simple example code: explicit_delete = True class Base: def __del__(self): print "Base class cleaning up." class Sub(Base): def __del__(self): print "Sub-class cleaning up." Base.__del__(self) x = Sub() if explicit_delete: del x print "End of thread" When I run this I get, as expected: Sub-class cleaning up. Base class cleaning up. End of thread If I set explicit_delete to False in the first line, I get: End of thread Sub-class cleaning up. Exception AttributeError: "'NoneType' object has no attribute '__del__'" in <bound method Sub.__del__ of <__main__.Sub instance at 0x00F0B698>> ignored It seems the definition of Base is removed before the x._del_() is called. The Python Documentation on _del_() warns that the subclass needs to call the base-class to get a clean deletion, but here that appears to be impossible. Can you see where I made a bad step?

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• WCF and ASP.NET - Server.Execute throwing object reference not set to an instance of an object

  - by user208662

  Hello, I have an ASP.NET page that calls to a WCF service. This WCF service uses a BackgroundWorker to asynchronously create an ASP.NET page on my server. Oddly, when I execute the WCF Service [OperationContract] [WebInvoke(Method = "POST", BodyStyle = WebMessageBodyStyle.WrappedRequest, RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json)] public void PostRequest(string comments) { // Do stuff // If everything went o.k. asynchronously render a page on the server. I do not want to // block the caller while this is occurring. BackgroundWorker myWorker = new BackgroundWorker(); myWorker.DoWork += new DoWorkEventHandler(myWorker_DoWork); myWorker.RunWorkerAsync(HttpContext.Current); } private void myWorker_DoWork(object sender, DoWorkEventArgs e) { // Set the current context so we can render the page via Server.Execute HttpContext context = (HttpContext)(e.Argument); HttpContext.Current = context; // Retrieve the url to the page string applicationPath = context.Request.ApplicationPath; string sourceUrl = applicationPath + "/log.aspx"; string targetDirectory = currentContext.Server.MapPath("/logs/"); // Execute the other page and load its contents using (StringWriter stringWriter = new StringWriter()) { // Write the contents out to the target url // NOTE: THIS IS WHERE MY ERROR OCCURS currentContext.Server.Execute(sourceUrl, stringWriter); // Prepare to write out the result of the log targetPath = targetDirectory + "/" + DateTime.Now.ToShortDateString() + ".aspx"; using (StreamWriter streamWriter = new StreamWriter(targetPath, false)) { // Write out the content to the file sb.Append(stringWriter.ToString()); streamWriter.Write(sb.ToString()); } } } Oddly, when the currentContext.Server.Execute method is executed, it throws an "object reference not set to an instance of an object" error. The reason this is so strange is because I can look at the currentContext properties in the watch window. In addition, Server is not null. Because of this, I have no idea where this error is coming from. Can someone point me in the correct direction of what the cause of this could be? Thank you!

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