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• Database cache that I'm not aware of?

  - by Martin

  I'm using asp.net mvc, linq2sql, iis7 and sqlserver express 2008. I get these intermittent server errors, primary key conflicts on insertion. I'm using a different setup on my development computer so I can't debug. After a while they go away. Restarting iis helps. I'm getting the feeling there is cache somewhere that I'm not aware of. Can somebody help me sort out these errors? Cannot insert duplicate key row in object 'dbo.EnquiryType' with unique index 'IX_EnquiryType'. Edits regarding Venemos answer Is it possible that another application is also accessing the same database simultaneously? Yes there is, but not this particular table and no inserts or updates. There is one other table with which I experience the same problem but it has to do with a different part of the model. How often an in what context do you create a new DataContext instance? Only once, using the singleton pattern. Are the primary keys generated by the database or by the application? Database. Which version of ASP.NET MVC and which version of .NET are you using? RC2 and 3.5.

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• How to systematically generate images from data?

  - by adamvickers

  I work for a performing arts nonprofit. We have seating charts for each of the theaters we work with; each seating chart shows the number of sections, the shape of each section, and the number of rows in each section. We'd like to create dynamic seating charts based on this info. We'd like them to look/feel kinda like this: http://www.fansnap.com/tickets/177754-on. But the tricky part is we'd like to be able to store all the info about each theater (the section names, shape/size of each section, and number of rows in each section) as data and then build a system that reads this data and uses it to create a dynamic map. I'm a life-long web developer, but I don't have have any experience with a difficult graphics problem like this. I realize it's a complex problem and I don't expect anyone to give me a complete answer here, but I would love direction on where I should be looking for more info. Is what I'm describing possible? Does this sort of technique have a name? Where can I learn more about how to accomplish this? What software should I use? Any info would be helpful.

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• Is std::move really needed on initialization list of constructor for heavy members passed by value?

  - by PiotrNycz

  Recently I read an example from cppreference.../vector/emplace_back: struct President { std::string name; std::string country; int year; President(std::string p_name, std::string p_country, int p_year) : name(std::move(p_name)), country(std::move(p_country)), year(p_year) { std::cout << "I am being constructed.\n"; } My question: is this std::move really needed? My point is that compiler sees that this p_name is not used in the body of constructor, so, maybe, there is some rule to use move semantics for it by default? That would be really annoying to add std::move on initialization list to every heavy member (like std::string, std::vector). Imagine hundreds of KLOC project written in C++03 - shall we add everywhere this std::move? This question: move-constructor-and-initialization-list answer says: As a golden rule, whenever you take something by rvalue reference, you need to use it inside std::move, and whenever you take something by universal reference (i.e. deduced templated type with &&), you need to use it inside std::forward But I am not sure: passing by value is rather not universal reference?

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• Adapting pseudocode to java implementation for finding the longest word in a trie

  - by user1766888

  Referring to this question I asked: How to find the longest word in a trie? I'm having trouble implementing the pseudocode given in the answer. findLongest(trie): //first do a BFS and find the "last node" queue <- [] queue.add(trie.root) last <- nil map <- empty map while (not queue.empty()): curr <- queue.pop() for each son of curr: queue.add(son) map.put(son,curr) //marking curr as the parent of son last <- curr //in here, last indicate the leaf of the longest word //Now, go up the trie and find the actual path/string curr <- last str = "" while (curr != nil): str = curr + str //we go from end to start curr = map.get(curr) return str This is what I have for my method public static String longestWord (DTN d) { Queue<DTN> holding = new ArrayQueue<DTN>(); holding.add(d); DTN last = null; Map<DTN,DTN> test = new ArrayMap<DTN,DTN>(); DTN curr; while (!holding.isEmpty()) { curr = holding.remove(); for (Map.Entry<String, DTN> e : curr.children.entries()) { holding.add(curr.children.get(e)); test.put(curr.children.get(e), curr); } last = curr; } curr = last; String str = ""; while (curr != null) { str = curr + str; curr = test.get(curr); } return str; } I'm getting a NullPointerException at: for (Map.Entry<String, DTN> e : curr.children.entries()) How can I find and fix the cause of the NullPointerException of the method so that it returns the longest word in a trie?

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• Item in multiple lists

  - by Evan Teran

  So I have some legacy code which I would love to use more modern techniques. But I fear that given the way that things are designed, it is a non-option. The core issue is that often a node is in more than one list at a time. Something like this: struct T { T *next_1; T *prev_1; T *next_2; T *prev_2; int value; }; this allows the core have a single object of type T be allocated and inserted into 2 doubly linked lists, nice and efficient. Obviously I could just have 2 std::list<T*>'s and just insert the object into both...but there is one thing which would be way less efficient...removal. Often the code needs to "destroy" an object of type T and this includes removing the element from all lists. This is nice because given a T* the code can remove that object from all lists it exists in. With something like a std::list I would need to search for the object to get an iterator, then remove that (I can't just pass around an iterator because it is in several lists). Is there a nice c++-ish solution to this, or is the manually rolled way the best way? I have a feeling the manually rolled way is the answer, but I figured I'd ask.

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• jQuery: AJAX call isn't updating page

  - by Cortopasta

  Thought I had a simple AJAX call using $.POST(), but apparently my function isn't firing, and nothing is updating :-/ Here is the call: $(".answerVerse ul li").click(function(){ var rank = $(this).removeClass("star_empty star_full star_highlight").attr("class"); var verse_id = $(this).parent().parent().find(".verseId").html(); var answer_id = $(this).parent().parent().find(".answerId").html(); var place = this; $.post("rank.php", { rank: rank, verse_id: verse_id, answer_id: answer_id },function(data){ $(place).parent().removeClass().addClass(data.newVerseRank); for (i=0;i<=5;i++) { $(".answerVerse ul."+i).each(function(){ $(".answerVerse ul."+i+" li."+i).prevAll().andSelf().removeClass("star_empty").addClass("star_full"); }); } }, "json"); }); And here is the PHP (rank.php) that it calls: require_once("dbcon.php"); $user = new user(); $user->updateVerseRank($_POST['verse_id'], $_POST['rank']); $user->getVerse($_POST['verse_id']); $user->getAnswer($_POST['answer_id']; $arr = array ('newVerseRank'=>htmlspecialchars(round($user->verse[3])),'newVerseVotes'=>htmlspecialchars(round($user->verse[4])),'newAnswerRank'=>htmlspecialchars($user->answer[3])); echo json_encode($arr); Why am I not updating the page? I know it's something dumb I'm doing seeing as how this is my first attempt at AJAX and JSON :-/ Just trying to learn

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• Does .Net use Device Dependent or Device Independent Bitmaps?

  - by Brian

  When loading an image into memory, does .Net use DDB, DIB, or something else entirely? If possible, please cite your sources. I'm wondering because we currently have a classic ASP application that is using a 3rd party component to load images that is occasionally creating a “Not enough storage is available to process this command.” error. The error is very inconsistent but tends to happen on larger images (not always, but often). After resetting IIS, processing the same file again typically works just fine. After much research I have found that DDBs tend to have this problem when processing large images because they work out of video memory. Considering that we are running on a web server with an integrated video card and limited shared memory, this could certainly be our problem. We are in the early stages of converting our app to .Net and am wondering if using .Net for this might be a viable alternative to our current method which is why I am asking the question. Any advice is welcome :) but out of curiosity if nothing else, I am really hoping for an answer to the question; does .Net use DDB or DIB?

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• Client Side Only Cookies

  - by Mike Jones

  I need something like a cookie, but I specifically don't want it going back to the server. I call it a "client side session cookie" but any reasonable mechanism would be great. Basically, I want to store some data encrypted on the server, and have the user type a password into the browser. The browser decrypts the data with the password (or creates and encrypts the data with the password) and the server stores only encrypted data. To keep the data secure on the server, the server should not store and should never receive the password. Ideally there should be a cookie session expiration to clean up. Of course I need it be available on multiple pages as the user walks through the web site. The best I can come up with is some sort of iframe mechanism to store the data in javascript variables, but that is ugly. Does anyone have any ideas how to implement something like this? FWIW, the platform is ASP.NET, but I don't suppose that matters. It needs to support a broad range of browsers, including mobile. In response to one answer below, let me clarify. My question is not how to achieve the crypto, that isn't a problem. The question is where to store the password so that it is persistent from page to page, but not beyond a session, and in such a way that the server doesn't see it.

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• How can you change the font color of a theme-enabled control?

  - by Edouard Westphal

  Yes, this is again this question: How can I change the font color of a TCheckBox (or any handled control) with Delphi7-Delphi2007 on a themes enabled application? After reading a lot on the internet and on this site, I found 4 kinds of answer: and Most populare (even from QC): You can't, it's designed like that by Microsoft. Create a component that let you draw it like you want. Buy expensive component set that draws like you want. Do not use themes. OK, but I am still unhappy with that. Giving a user colored feedback for the status of a property/data he has on a form, seems legitimate to me. Then I just installed the MSVC# 2008 Express edition, and what a surprise, they can change the color of the font (property ForeColor of the check box) Then what? It does not seem to be a "it's designed like that, by Microsoft." then now the question again: How can I change the font color of a TCheckBox (or any handled control) with Delphi 7 through Delphi 2007 on a theme-enabled application?

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• C++ Matrix class hierachy

  - by bpw1621

  Should a matrix software library have a root class (e.g., MatrixBase) from which more specialized (or more constrained) matrix classes (e.g., SparseMatrix, UpperTriangluarMatrix, etc.) derive? If so, should the derived classes be derived publicly/protectively/privately? If not, should they be composed with a implementation class encapsulating common functionality and be otherwise unrelated? Something else? I was having a conversation about this with a software developer colleague (I am not per se) who mentioned that it is a common programming design mistake to derive a more restricted class from a more general one (e.g., he used the example of how it was not a good idea to derive a Circle class from an Ellipse class as similar to the matrix design issue) even when it is true that a SparseMatrix "IS A" MatrixBase. The interface presented by both the base and derived classes should be the same for basic operations; for specialized operations, a derived class would have additional functionality that might not be possible to implement for an arbitrary MatrixBase object. For example, we can compute the cholesky decomposition only for a PositiveDefiniteMatrix class object; however, multiplication by a scalar should work the same way for both the base and derived classes. Also, even if the underlying data storage implementation differs the operator()(int,int) should work as expected for any type of matrix class. I have started looking at a few open-source matrix libraries and it appears like this is kind of a mixed bag (or maybe I'm looking at a mixed bag of libraries). I am planning on helping out with a refactoring of a math library where this has been a point of contention and I'd like to have opinions (that is unless there really is an objective right answer to this question) as to what design philosophy would be best and what are the pros and cons to any reasonable approach.

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• Use SQL to clone a tree structure represented in a database

  - by AmoebaMan17

  Given a table that represents a hierarchical tree structure and has three columns ID (Primary Key, not-autoincrementing) ParentGroupID SomeValue I know the lowest most node of that branch, and I want to copy that to a new branch with the same number of parents that also need to be cloned. I am trying to write a single SQL INSERT INTO statement that will make a copy of every row that is of the same main has is part one GroupID into a new GroupID. Example beginning table: ID | ParentGroupID | SomeValue ------------------------ 1 | -1 | a 2 | 1 | b 3 | 2 | c Goal after I run a simple INSERT INTO statement: ID | ParentGroupID | SomeValue ------------------------ 1 | -1 | a 2 | 1 | b 3 | 2 | c 4 | -1 | a-cloned 5 | 4 | b-cloned 6 | 5 | c-cloned Final tree structure +--a (1) | +--b (2) | +--c (3) | +--a-cloned (4) | +--b-cloned (5) | +--c-cloned (6) The IDs aren't always nicely spaced out as this demo data is showing, so I can't always assume that the Parent's ID is 1 less than the current ID for rows that have parents. Also, I am trying to do this in T-SQL (for Microsoft SQL Server 2005 and greater). This feels like a classic exercise that should have a pure-SQL answer, but I'm too used to programming that my mind doesn't think in relational SQL.

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• How to limit setAccessible to only "legitimate" uses?

  - by polygenelubricants

  The more I learned about the power of setAccessible, the more astonished I am at what it can do. This is adapted from my answer to the question (Using reflection to change static final File.separatorChar for unit testing). import java.lang.reflect.*; public class EverythingIsTrue { static void setFinalStatic(Field field, Object newValue) throws Exception { field.setAccessible(true); Field modifiersField = Field.class.getDeclaredField("modifiers"); modifiersField.setAccessible(true); modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL); field.set(null, newValue); } public static void main(String args[]) throws Exception { setFinalStatic(Boolean.class.getField("FALSE"), true); System.out.format("Everything is %s", false); // "Everything is true" } } You can do truly outrageous stuff: public class UltimateAnswerToEverything { static Integer[] ultimateAnswer() { Integer[] ret = new Integer[256]; java.util.Arrays.fill(ret, 42); return ret; } public static void main(String args[]) throws Exception { EverythingIsTrue.setFinalStatic( Class.forName("java.lang.Integer$IntegerCache") .getDeclaredField("cache"), ultimateAnswer() ); System.out.format("6 * 9 = %d", 6 * 9); // "6 * 9 = 42" } } Presumably the API designers realize how abusable setAccessible can be, but must have conceded that it has legitimate uses to provide it. So my questions are: What are the truly legitimate uses for setAccessible? Could Java has been designed as to NOT have this need in the first place? What would the negative consequences (if any) of such design be? Can you restrict setAccessible to legitimate uses only? Is it only through SecurityManager? How does it work? Whitelist/blacklist, granularity, etc? Is it common to have to configure it in your applications?

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• Fastest way to perform subset test operation on a large collection of sets with same domain

  - by niktech

  Assume we have trillions of sets stored somewhere. The domain for each of these sets is the same. It is also finite and discrete. So each set may be stored as a bit field (eg: 0000100111...) of a relatively short length (eg: 1024). That is, bit X in the bitfield indicates whether item X (of 1024 possible items) is included in the given set or not. Now, I want to devise a storage structure and an algorithm to efficiently answer the query: what sets in the data store have set Y as a subset. Set Y itself is not present in the data store and is specified at run time. Now the simplest way to solve this would be to AND the bitfield for set Y with bit fields of every set in the data store one by one, picking the ones whose AND result matches Y's bitfield. How can I speed this up? Is there a tree structure (index) or some smart algorithm that would allow me to perform this query without having to AND every stored set's bitfield? Are there databases that already support such operations on large collections of sets?

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• Selectively search and replace certain lines using a regular expression

  - by eneveu

  I have a file containing a lot of SQL statements, such as: CREATE TABLE "USER" ( "ID" INTEGER PRIMARY KEY, "NAME" CHARACTER VARYING(50) NOT NULL, "AGE" INTEGER NOT NULL ); COPY "USER" (id, name, age) FROM stdin; 1 Skywalker 19 2 Kenobi 57 I want the column names in the COPY statements to be uppercased and quoted: COPY "USER" ("ID", "NAME", "AGE") FROM stdin; Using sed, I found the following regexp: sed -r 's/([( ])(\w+)([,)])/\1"\U\2\E"\3/g' It does replace the column names, but it is not selective enough, and replaces other words in the file: ~/test]$sed -r 's/([( ])(\w+)([,)])/\1"\U\2\E"\3/g' star_wars_example CREATE TABLE "USER" ( "ID" INTEGER PRIMARY "KEY", "NAME" CHARACTER VARYING("50")NOT "NULL", "AGE" INTEGER NOT NULL ); COPY "USER" ("ID", "NAME", "AGE") FROM stdin; 1 Skywalker 19 2 Kenobi 57 To avoid this problem, I want sed to only apply my regexp to the lines starting with COPY and ending with FROM stdin;. I have looked into lookahead / lookbehind, but they are not supported in sed. They seem to be supported in super-sed, but I am currently using Cygwin (Windows is mandatory here...) and it does not seem available in the package list. Is there a way to force sed to only consider specific line? I've considered piping my file through grep before applying sed, but other lines will then disappear from the output. Am I missing something obvious? It would be great if the answer was easily applicable on a default Cygwin install. I guess I could try installing super-sed on cygwin, but I'd like to know if there are more obvious ideas

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• OpenSource Projects - Is there a site which lists projecs that need more developers?

  - by Jamie

  Morning/Afternoon/Evening all, Do any of you know of a website which lists opensource projects which are in need of more help? Let me elaborate, I would like to work on another open source project (I already work on a couple), however, it would be nice to have a site which lists lots of OS projects, their aims, deadlines, workload, how many more developers they are in need of etc. Of course, I could just pick a topic i'm interested in, find an OS project and then work on it, however, it would be nice to see a diversified list of projects. Primarily because some little known awesome projects get little attention and big projects such as jQuery forks, adium, gimp etc. etc. get a lot of attention because they are well known (and of course because they are great)and thus get a lot of developers working on them. It would be nice to see some little known projects getting more attention and thus hopefully drawing some people to work on them. Currently there are many websites hosting os projects, such as github, sourceforge, google code etc. A website to centralise all of this into one place and categorise it would be awesome. Let me know your thoughts please. I'm not looking for an answer per se, so I will mark it is as a community wiki. Your thoughts would be great.

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• How to get the set of beans that are to be created in Spring?

  - by cyborg

  So here's the scenario: I have a Spring XML configuration with some lazy-beans, some not lazy-beans and some beans that depend on other beans. Eventually Spring will resolve all this so that only the beans that are meant to be created are created. The question: how can I programmatically tell what this set is? When I use context.getBean(name) that initializes the bean. BeanDefinition.isLazyInit() will only tell me how I defined the bean. Any other ideas? ETA: In DefaultListableBeanFactory: public void preInstantiateSingletons() throws BeansException { if (this.logger.isInfoEnabled()) { this.logger.info("Pre-instantiating singletons in " + this); } synchronized (this.beanDefinitionMap) { for (Iterator it = this.beanDefinitionNames.iterator(); it.hasNext();) { String beanName = (String) it.next(); RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName); if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) { if (isFactoryBean(beanName)) { FactoryBean factory = (FactoryBean) getBean(FACTORY_BEAN_PREFIX + beanName); if (factory instanceof SmartFactoryBean && ((SmartFactoryBean) factory).isEagerInit()) { getBean(beanName); } } else { getBean(beanName); } } } } } The set of instantiable beans is initialized. When initializing this set any beans not in this set referenced by this set will also be created. From looking through the source it does not look like there's going to be any easy way to answer my question.

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• Give the mount point of a path

  - by Charles Stewart

  The following, very non-robust shell code will give the mount point of $path: (for i in $(df|cut -c 63-99); do case $path in $i*) echo $i;; esac; done) | tail -n 1 Is there a better way to do this? Postscript This script is really awful, but has the redeeming quality that it Works On My Systems. Note that several mount points may be prefixes of $path. Examples On a Linux system: cas@txtproof:~$ path=/sys/block/hda1 cas@txtproof:~$ for i in $(df -a|cut -c 57-99); do case $path in $i*) echo $i;; esac; done| tail -1 /sys On a Mac osx system cas local$ path=/dev/fd/0 cas local$ for i in $(df -a|cut -c 63-99); do case $path in $i*) echo $i;; esac; done| tail -1 /dev Note the need to vary cut's parameters, because of the way df's output differs: indeed, awk is better. Answer It looks like munging tabular output is the only way within the shell, but df /dev/fd/impossible | tail -1 | awk '{ print $NF}' is a big improvement on what I had. Note two differences in semantics: firstly, df $path insists that $path names an existing file, the script I had above doesn't care; secondly, there are no worries about dereferncing symlinks. It's not difficult to write Python code to do the job.

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• Why does my DIV clip its child DIV when jQuery moves it in IE?

  - by Ben Saufley

  I have two divs, both with position:absolute;, one inside the other. The parent isn't in a place where it can be set as position:relative without an extra layer of complexity (there are a lot of other elements around it that I'd have to account for to put it where it needs to be, which is at the very top of the page, over everything). The child element is made to stick off the bottom of the parent. In Chrome, Safari, Firefox, it all works splendidly. In IE, it works until jQuery moves the parent element - at which point the parent element clips the child, so you can barely see the top of the child. I feel like I've read about this, about IE clipping child elements, but I can't seem to find an answer that applies to my case. It's pretty simple, basically: <div id="parent" style="position:absolute;top:0;left:0;"> [content] <div id="tab" style="position:absolute;bottom:-30px;left:0;width:64px;height:32px;background-image:(...);"></div> </div> <script> $(document).ready( function() { $("#tab").click(function() { $("#parent").animate({"top":"-50px"},300); }); }); </script>

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• Cross Thread problem C#

  - by Frederik Witte

  Hello people - I got this code (lg_log is a listbox, and i want it to log the start_server.bat) Here is the code i got: public void bt_play_Click(object sender, EventArgs e) { lg_log.Items.Add("Starting Mineme server .."); string directory = Directory.GetCurrentDirectory(); var info = new ProcessStartInfo(directory + @"\start_base.bat") {UseShellExecute = false, RedirectStandardOutput = true, CreateNoWindow = true, WorkingDirectory = directory + @"\Servers\Base"}; var proc = new Process { StartInfo = info, EnableRaisingEvents = true }; proc.OutputDataReceived += (obj, args) => { if (args.Data != null) { lg_log.Items.Add(args.Data); } }; proc.Start(); proc.BeginOutputReadLine(); lg_log.Items.Add("Server is now running!"); proc.WaitForExit(); } When i run this, i'll get an error .. Anybody can help me? I'll rate the answer up! :D Edit: The error i get is this: System.InvalidOperationException Hope it helps :) The error comes at the lg_log.Items.Add(args.Data); code line

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• Are C++ exceptions sufficient to implement thread-local storage?

  - by Potatoswatter

  I was commenting on an answer that thread-local storage is nice and recalled another informative discussion about exceptions where I supposed The only special thing about the execution environment within the throw block is that the exception object is referenced by rethrow. Putting two and two together, wouldn't executing an entire thread inside a function-catch-block of its main function imbue it with thread-local storage? It seems to work fine: #include <iostream> #include <pthread.h> using namespace std; struct thlocal { string name; thlocal( string const &n ) : name(n) {} }; thlocal &get_thread() { try { throw; } catch( thlocal &local ) { return local; } } void print_thread() { cerr << get_thread().name << endl; } void *kid( void *local_v ) try { thlocal &local = * static_cast< thlocal * >( local_v ); throw local; } catch( thlocal & ) { print_thread(); return NULL; } int main() try { thlocal local( "main" ); throw local; } catch( thlocal & ) { print_thread(); pthread_t th; thlocal kid_local( "kid" ); pthread_create( &th, NULL, &kid, &kid_local ); pthread_join( th, NULL ); print_thread(); return 0; } Is this novel or well-characterized? Was my initial premise correct? What kind of overhead does get_thread incur in, say, GCC and VC++? It would require throwing only exceptions derived from struct thlocal, but altogether this doesn't feel like an unproductive insomnia-ridden Sunday morning…

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• Configuring the GPS Intermediate Driver

  - by Zach Smith

  Hello, I have a Motorola MC75 with an integrated GPS system that I am trying to use for programming. I have done some research on it and tried setting it up by editing the remote registry of the device according to some specifications that I found on the internet on this blog, http://csharponphone.blogspot.com/2007/07/configuring-gps-intermediate-driver.html. I used the smart phone guide at the bottom of the page but to no avail. Currently, I am trying to test it with the GPS application provided in the Windows Mobile 6 SDK samples. The program will load and begin what looks like the search for satellites but will not locate anything. I do not think the GPS is set up correctly. Does anyone have any helpful insight onto this issue or a guide for configuring the GPSID? Thank you in advance. Also, I have already checked and tried some of the config help on MSDN which does not help me either. I will surely vote for the most helpful answer. Thanks, Zach

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• What does "Select Distinct Null As xxxxx" mean?

  - by Soylent Green

  Background: I am mapping Sybase stored procedure return values to java objects using Spring. For example I map a Sybase datatype of varchar as a String type in Java, and a Sybase datatype of int as an int type in Java, etc. I have come across the following code in one of the stored procedures: SELECT DISTINCT A.Col1 AS val1, A.Col2 AS val2, NULL AS someVal, A.col3 AS val3, ... A.col9 AS val9 FROM #SomeTable A ORDER BY Col2, Col3 I have 2 related questions: What does Null mean in this scenario? I am confused as to what is happening here. I am able to determine the data type of Col1, Col2, etc. of course by looking at the table definition of Table A defined earlier in the stored procedure. Thus I know what datatype I can define in my Java object for val1, val2, etc.. But what about "someVal"? What datatype mapping am I supposed to perform for this Null value? I am fairly inexperienced in SQL. Perhaps the answer is much simpler than I realize.

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• TCP Socket.Connect is generating false positives

  - by Mark

  I'm experiencing really weird behavior with the Socket.Connect method in C#. I am attempting a TCP Socket.Connect to a valid IP but closed port and the method is continuing as if I have successfully connected. When I packet sniffed what was going on I saw that the app was receiving RST packets from the remote machine. Yet from the tracing that is in place it is clear that the connect method is not throwing an exception. Any ideas what might be causing this? The code that is running is basically this IPEndPoint iep = new IPEndPoint(System.Net.IPAddress.Parse(m_ipAddress), m_port); Socket tcpSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); tcpSocket.Connect(iep); To add to the mystery... when running this code in a stand alone console application, the result is as expected – the connect method throws an exception. However, when running it in the Windows Service deployment we have the connect method does not throw an exception. Edit in response to Mystere Man's answer How would the exception be swallowed? I have a Trace.WriteLine right above the .Connect method and a Trace.WriteLine right under it (not shown in the code sample for readability). I know that both traces are running. I also have a try catch around the whole thing which also does a Trace.Writeline and I don't see that in the log files anywhere. I have also enabled the internal socket tracing as you suggested. I don't see any exceptions. I see what appears to be successful connections. I am trying to identify differences between the windows service app and the diagnostic console app I made. I am running out of ideas though End edit Thanks

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• C++ polymorphism, function calls

  - by moai

  Okay, I'm pretty inexperienced as a programmer, let alone in C++, so bear with me here. What I wanted to do was to have a container class hold a parent class pointer and then use polymorphism to store a child class object. The thing is that I want to call one of the child class's functions through the parent class pointer. Here's a sort of example of what I mean in code: class SuperClass { public: int x; } class SubClass : public SuperClass { public: void function1() { x += 1; } } class Container { public: SuperClass * alpha; Container(SuperClass& beta) { alpha = beta; } } int main() { Container cont = new Container(new SubClass); } (I'm not sure that's right, I'm still really shaky on pointers. I hope it gets the point across, at least.) So, I'm not entirely sure whether I can do this or not. I have a sneaking suspicion the answer is no, but I want to be sure. If someone has another way to accomplish this sort of thing, I'd be glad to hear it.

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• What does P mean in Sort(Expression<Func<T, P>> expr, ListSortDirection direction)?

  - by Grasshopper

  I am attempting to use the answer in post: How do you sort an EntitySet<T> to expose an interface so that I can sort an EntitySet with a Binding list. I have created the class below and I get the following compiler error: "The type or namespace 'P' could not be found (are you missing a using directive or assembly reference?). Can someone tell me what the P means and which namespace I need to include to get the method below to compile? I am very new to delegates and lamba expressions. Also, can someone confirm that if I create a BindingList from my EntitySet that any modifications I make to the BindingList will be made to the EntitySet? Basically, I have an EntitySet that I need to sort and make changes to. Then, I will need to persist these changes using the original Entity that the BindingList came from. public class EntitySetBindingWrapper<T> : BindingList<T> { public EntitySetBindingWrapper(BindingList<T> root) : base(root) { } public void Sort(Expression<Func<T, P>> expr, ListSortDirection direction) { if (expr == null) base.RemoveSortCore(); MemberExpression propExpr = expr as MemberExpression; if (propExpr == null) throw new ArgumentException("You must provide a property", "expr"); PropertyDescriptorCollection descriptorCol = TypeDescriptor.GetProperties(typeof(T)); IEnumerable<PropertyDescriptor> descriptors = descriptorCol.Cast<PropertyDescriptor>(); PropertyDescriptor descriptor = descriptors.First(pd => pd.Name == propExpr.Member.Name); base.ApplySortCore(descriptor, direction); } }

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