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• How to update GUI thread/class from worker thread/class?

  - by user315182

  First question here so hello everyone. The requirement I'm working on is a small test application that communicates with an external device over a serial port. The communication can take a long time, and the device can return all sorts of errors. The device is nicely abstracted in its own class that the GUI thread starts to run in its own thread and has the usual open/close/read data/write data basic functions. The GUI is also pretty simple - choose COM port, open, close, show data read or errors from device, allow modification and write back etc. The question is simply how to update the GUI from the device class? There are several distinct types of data the device deals with so I need a relatively generic bridge between the GUI form/thread class and the working device class/thread. In the GUI to device direction everything works fine with [Begin]Invoke calls for open/close/read/write etc. on various GUI generated events. I've read the thread here (How to update GUI from another thread in C#?) where the assumption is made that the GUI and worker thread are in the same class. Google searches throw up how to create a delegate or how to create the classic background worker but that's not at all what I need, although they may be part of the solution. So, is there a simple but generic structure that can be used? My level of C# is moderate and I've been programming all my working life, given a clue I'll figure it out (and post back)... Thanks in advance for any help.

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• PHP: Join two separate mysql queries into the same json data object

  - by Dan

  I'm trying to mesh the below mysql query results into a single json object, but not quite sure how to do it properly. //return data $sql_result = mysql_query($sql,$connection) or die ("Fail."); $arr = array(); while($obj = mysql_fetch_object($sql_result)) { $arr[] = $obj; } echo json_encode($arr); //return json //plus the selected options $sql_result2 = mysql_query($sql2,$connection) or die ("Fail."); $arr2 = array(); while($obj2 = mysql_fetch_object($sql_result2)) { $arr2[] = $obj2; } echo json_encode($arr2); //return json Here's the current result: [{"po_number":"test","start_date":"1261116000","end_date":"1262239200","description":"test","taa_required":"0","account_overdue":"1","jobs_id":null,"job_number":null,"companies_id":"4","companies_name":"Primacore Inc."}][{"types_id":"37"},{"types_id":"4"}] Notice how the last section [{"types_id":"37"},{"types_id":"4"}] is placed into a separate chunk under root. I'm wanting it to be nested inside the first branch under a name like, "types". I think my question has more to do with Php array manipulation, but I'm not the best with that. Thank you for any guidance.

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• How to easily map c++ enums to strings

  - by Roddy

  I have a bunch of enum types in some library header files that I'm using, and I want to have a way of converting enum values to user strings - and vice-versa. RTTI won't do it for me, because the 'user strings' need to be a bit more readable than the enumerations. A brute force solution would be a bunch of functions like this, but I feel that's a bit too C-like. enum MyEnum {VAL1, VAL2,VAL3}; String getStringFromEnum(MyEnum e) { switch e { case VAL1: return "Value 1"; case VAL2: return "Value 2"; case VAL1: return "Value 3"; default: throw Exception("Bad MyEnum"); } } I have a gut feeling that there's an elegant solution using templates, but I can't quite get my head round it yet. UPDATE: Thanks for suggestions - I should have made clear that the enums are defined in a third-party library header, so I don't want to have to change the definition of them. My gut feeling now is to avoid templates and do something like this: char * MyGetValue(int v, char *tmp); // implementation is trivial #define ENUM_MAP(type, strings) char * getStringValue(const type &T) \ { \ return MyGetValue((int)T, strings); \ } ; enum eee {AA,BB,CC}; - exists in library header file ; enum fff {DD,GG,HH}; ENUM_MAP(eee,"AA|BB|CC") ENUM_MAP(fff,"DD|GG|HH") // To use... eee e; fff f; std::cout<< getStringValue(e); std::cout<< getStringValue(f);

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• Implementing a c/c++ style union as a column in MySQL

  - by user81338

  Friends, I have a strange need and cannot think my way through the problem. The great and mighty Google is of little help due to keyword recycling (as you'll see). Can you help? What I want to do is store data of multiple types in a single column in MySQL. This is the database equivalent to a C union (and if you search for MySQL and Union, you obviously get a whole bunch of stuff on the UNION keyword in SQL). [Contrived and simplified case follows] So, let us say that we have people - who have names - and STORMTROOPERS - who have TK numbers. You cannot have BOTH a NAME and a TK number. You're either BOB SMITH -or- TK409. In C I could express this as a union, like so: union { char * name; int tkNo; } EmperialPersonnelRecord; This makes it so that I am either storing a pointer to a char array or an ID in the type EmperialPersonnelRecord, but not both. I am looking for a MySQL equivalent on a column. My column would store either an int, double, or varchar(255) (or whatever combination). But would only take up the space of the largest element. Is this possible? (of course anything is possible given enough time, money and will - I mean is it possible if I am poor, lazy and on a deadline... aka "out of the box")

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• Most efficient method of detecting/monitoring DOM changes?

  - by Graza

  I need an efficient mechanism for detecting changes to the DOM. Preferably cross-browser, but if there's any efficient means which are not cross browser, I can implement these with a fail-safe cross browser method. In particular, I need to detect changes that would affect the text on a page, so any new, removed or modified elements, or changes to inner text (innerHTML) would be required. I don't have control over the changes being made (they could be due to 3rd party javascript includes, etc), so it can't be approached from this angle - I need to "monitor" for changes somehow. Currently I've implemented a "quick'n'dirty" method which checks body.innerHTML.length at intervals. This won't of course detect changes which result in the same length being returned, but in this case is "good enough" - the chances of this happening are extremely slim, and in this project, failing to detect a change won't result in lost data. The problem with body.innerHTML.length is that it's expensive. It can take between 1 and 5 milliseconds on a fast browser, and this can bog things down a lot - I'm also dealing with a large-ish number of iframes and it all adds up. I'm pretty sure the expensiveness of doing this is because the innerHTML text is not stored statically by browsers, and needs to be calculated from the DOM every time it is read. The types of answers I am looking for are anything from the "precise" (for example event) to the "good enough" - perhaps something as "quick'n'dirty" as the innerHTML.length method, but that executes faster.

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• using STI and ActiveRecordBase<> with full FindAll

  - by oillio

  Is it possible to use generic support with single table inheritance, and still be able to FindAll of the base class? As a bonus question, will I be able to use ActiveRecordLinqBase< as well? I do love those queries. More detail: Say I have the following classes defined: public interface ICompany { int ID { get; set; } string Name { get; set; } } [ActiveRecord("companies", DiscriminatorColumn="type", DiscriminatorType="String", DiscriminatorValue="NA")] public abstract class Company<T> : ActiveRecordBase<T>, ICompany { [PrimaryKey] private int Id { get; set; } [Property] public String Name { get; set; } } [ActiveRecord(DiscriminatorValue="firm")] public class Firm : Company<Firm> { [Property] public string Description { get; set; } } [ActiveRecord(DiscriminatorValue="client")] public class Client : Company<Client> { [Property] public int ChargeRate { get; set; } } This works fine for most cases. I can do things like: var x = Client.FindAll(); But sometimes I want all of the companies. If I was not using generics I could do: var x = (Company[]) FindAll(Company); Client a = (Client)x[0]; Firm b = (Firm)x[1]; Is there a way to write a FindAll that returns an array of ICompany's that can then be typecast into their respective types? Something like: var x = (ICompany[]) FindAll(Company<ICompany>); Client a = (Client)x[0]; Or maybe I am going about implementing the generic support all wrong?

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• Web Hosting: Any web host that supports files more than 50,000 in number?

  - by Devner

  Hi all, For my PHP & mySQL based application, I am trying to buy website hosting from a host who does not have a limit on the number of files I carry in my hosting account. Almost all the websites have a common limit of 50,000 files (some websites call it 50,000 nodes). The rest(to the extent of my search) are not even close. I have gone through the various websites, Googled lot of information, have spoken with the customer service of the hosting companies and they said that they have a limit of 50,000 files and that's why they call it the LIMIT. Now I have my application, which is a kind of social networking website, where people can upload various files of varying file size. So say if 50,000 users were to join the website and upload 1 file each, the limit of 50,000 will be reached very easily and my 50,001 customer will start facing file upload problems (& so will my account). So I would like to know if there's any website hosting services that do NOT levy such restrictions. In summary, I need the following options: No maximum file limit (more than 50,000 files in account). No maximum file upload limit in server setting (10MB, 12MB, 15MB, 20MB, etc.). Ability to upload files of various types (zip, flv, jg, png, etc.). Ability to stream Audio and Video (live audio & video not necessary). Access to .htaccess Access to php.ini, my.cnf or my.ini (this would be a plus) Supports SSL. Provides dedicated hosting(& IP) as well. Monthly payments without contracts are a plus. If you know of any such website hosting services, please post a reply ( a link to the same will be appreciated ). Thank you.

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• SqlCE DB occasionally freezes on one handheld, not another

  - by Michael

  I have two types of custom handhelds which are similar, but slightly different, each running the same WinForm application and a WinCE database: Type 1: WinCE 4.2, 400 mhz, 93244 kb Type 2: WinCE 5.0, 520 mhz, 84208 kb Type 1 will happily proceed through a large batch db operation (initiated) by the app, by Type 2 will consistently begin c-r-a-w-l-i-n-g (for several to many cycles) at around the 200 cycle mark. As several points it will begin running normally and then crawl again. The app does several db op's (inserts, updates and selects, no deletes). To simplify my situation, I've built a small test app which essentially does this: command_s.CommandText = "select dvr from vr where vid = 2211250"; command_u.CommandText = "update pvr set LocationID=81 where Status='OK' and vri = 27861"; while(going) { command_s.ExecuteScalar(); command_u.ExecuteNonQuery(); } and set it off running on the two units side by side. Sure enough, the slower (400 mhz) unit is outpacing the faster (520 mhz) unit (it's about 5000 cycles ahead right now) and I can see noticable pauses on the 520 mhz unit. What is causing this?

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• Is context:annotation-config an alternative to @AutoWired?

  - by Antacid

  Is it correct that I can put context:annotation-config in my XML config and it will automatically inject the bean class without needing any annotations? So instead of using these annotation types: public class Mailman { private String name; @Autowired private Parcel Parcel; public Mailman(String name) { this.name = name; } @Autowired public void setParcel(Parcel Parcel) { this.Parcel = Parcel; } @Autowired public void directionsToParcel(Parcel Parcel) { this.Parcel = Parcel; } } I would just need to write this: <beans ... > <bean id="mailMan" class="MailMan"> <constructor-arg value="John Doe"/> </bean> <bean id="parcel" class="Parcel" /> <context:annotation-config /> </beans> and then my MailMan class would look a lot simpler without the need for annotations: public class Mailman { private String name; private Parcel Parcel; public Mailman(String name) { this.name = name; } }

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• Java: Generics, Class.isaAssignableFrom, and type casting

  - by bguiz

  This method that uses method-level generics, that parses the values from a custom POJO, JXlistOfKeyValuePairs (which is exactly that). The only thing is that both the keys and values in JXlistOfKeyValuePairs are Strings. This method wants to taken in, in addition to the JXlistOfKeyValuePairs instance, a Class<T> that defines which data type to convert the values to (assume that only Boolean, Integer and Float are possible). It then outputs a HashMap with the specified type for the values in its entries. This is the code that I have got, and it is obviously broken. private <T extends Object> Map<String, T> fromListOfKeyValuePairs(JXlistOfKeyValuePairs jxval, Class<T> clasz) { Map<String, T> val = new HashMap<String, T>(); List<Entry> jxents = jxval.getEntry(); T value; String str; for (Entry jxent : jxents) { str = jxent.getValue(); value = null; if (clasz.isAssignableFrom(Boolean.class)) { value = (T)(Boolean.parseBoolean(str)); } else if (clasz.isAssignableFrom(Integer.class)) { value = (T)(Integer.parseInt(str)); } else if (clasz.isAssignableFrom(Float.class)) { value = (T)(Float.parseFloat(str)); } else { logger.warn("Unsupporteded value type encountered in key-value pairs, continuing anyway: " + clasz.getName()); } val.put(jxent.getKey(), value); } return val; } This is the bit that I want to solve: if (clasz.isAssignableFrom(Boolean.class)) { value = (T)(Boolean.parseBoolean(str)); } else if (clasz.isAssignableFrom(Integer.class)) { value = (T)(Integer.parseInt(str)); } I get: Inconvertible types required: T found: Boolean Also, if possible, I would like to be able to do this with more elegant code, avoiding Class#isAssignableFrom. Any suggestions? Sample method invocation: Map<String, Boolean> foo = fromListOfKeyValuePairs(bar, Boolean.class);

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• Recursive QuickSort suffering a StackOverflowException -- Need fresh eyes

  - by jon

  I am working on a Recursive QuickSort method implementation in a GenericList Class. I will have a second method that accepts a compareDelegate to compare different types, but for development purposes I'm sorting a GenericList<int I am recieving stackoverflow areas in different places depending on the list size. I've been staring at and tracing through this code for hours and probably just need a fresh pair of (more experienced)eyes. Definitely wanting to learn why it is broken, not just how to fix it. public void QuickSort() { int i, j, lowPos, highPos, pivot; GenericList<T> leftList = new GenericList<T>(); GenericList<T> rightList = new GenericList<T>(); GenericList<T> tempList = new GenericList<T>(); lowPos = 1; highPos = this.Count; if (lowPos < highPos) { pivot = (lowPos + highPos) / 2; for (i = 1; i <= highPos; i++) { if (this[i].CompareTo(this[pivot]) <= 0) leftList.Add(this[i]); else rightList.Add(this[i]); } leftList.QuickSort(); rightList.QuickSort(); for(i=1;i<=leftList.Count;i++) tempList.Add(leftList[i]); for(i=1;i<=rightList.Count;i++) tempList.Add(rightList[i]); this.items = tempList.items; this.count = tempList.count; } }

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• Full-text search in C++

  - by Jen

  I have a database of many (though relatively short) HTML documents. I want users to be able to search this database by entering one or more search words in a C++ desktop application. Hence, I’m looking for a fast full-text search solution. Ideally, it should: Skip common words, such as the, of, and, etc. Support stemming, i.e. search for run also finds documents containing runner, running and ran. Be able to update its index in the background as new documents are added to the database. Be able to provide search word suggestions (like Google Suggest) To illustrate, assume the database has just two documents: Document 1: This is a test of text search. Document 2: Testing is fun. The following words should be in the index: fun, search, test, testing, text. If the user types t in the search box, I want the application to be able to suggest test, testing and text (Ideally, the application should be able to query the search engine for the 10 most common search words starting with t). A search for testing should return both documents. Can you suggest a C or C++ based solution? (I’ve briefly reviewed CLucene and Xapian, but I’m not sure if either will address my needs, especially querying the search word indexes for the suggest feature).

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• NHibernate / Fluent - Mapping multiple objects to single lookup table

  - by Al

  Hi all I am struggling a little in getting my mapping right. What I have is a single self joined table of look up values of certain types. Each lookup can have a parent, which can be of a different type. For simplicities sake lets take the Country and State example. So the lookup table would look like this: Lookups Id Key Value LookupType ParentId - self joining to Id base class public class Lookup : BaseEntity { public Lookup() {} public Lookup(string key, string value) { Key = key; Value = value; } public virtual Lookup Parent { get; set; } [DomainSignature] [NotNullNotEmpty] public virtual LookupType LookupType { get; set; } [NotNullNotEmpty] public virtual string Key { get; set; } [NotNullNotEmpty] public virtual string Value { get; set; } } The lookup map public class LookupMap : IAutoMappingOverride<DBLookup> { public void Override(AutoMapping<Lookup> map) { map.Table("Lookups"); map.References(x => x.Parent, "ParentId").ForeignKey("Id"); map.DiscriminateSubClassesOnColumn<string>("LookupType").CustomType(typeof(LookupType)); } } BASE SubClass map for subclasses public class BaseLookupMap : SubclassMap where T : DBLookup { protected BaseLookupMap() { } protected BaseLookupMap(LookupType lookupType) { DiscriminatorValue(lookupType); Table("Lookups"); } } Example subclass map public class StateMap : BaseLookupMap<State> { protected StateMap() : base(LookupType.State) { } } Now I've almost got my mappings set, however the mapping is still expecting a table-per-class setup, so is expecting a 'State' table to exist with a reference to the states Id in the Lookup table. I hope this makes sense. This doesn't seem like an uncommon approach when wanting to keep lookup-type values configurable. Thanks in advance. Al

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• How do I create a simple Windows form to access a SQL Server database?

  - by NoCatharsis

  I believe this is a very novice question, and if I'm using the wrong forum to ask, please advise. I have a basic understanding of databasing with MS SQL Server, and programming with C++ and C#. I'm trying to teach myself more by setting up my own database with MS SQL Server Express 2008 R2 and accessing it via Windows forms created in C# Express 2010. At this point, I just want to keep it to free or Express dev tools (not necessarily Microsoft though). Anyway, I created a database using the instructions provided here and I set the data types appropriately for each column (no errors in setup at least). Now I'm designing the GUI in C# Express but I've kind of hit a wall as far as the database connection. Is there a simple way to access the database I created locally using C# Express? Can anyone suggest a guide that has all this spelled out already? I am a self-learner so I look forward to teaching myself how to use these applications, but any pointers to start me off in the right direction would be greatly appreciated.

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• Are there Windows API binaries for Subversion or do I have to build SVN to call the API from Windows

  - by JeffH

  I want to call a Subversion API from a Visual Studio 2003 C++ project. I know there are threads here, here, here, and here that tell how to get started with C#.NET on Windows (the consensus seems to be SharpSvn, which I've used easily and successfully on another project) but that's not what I want. I've read the chapter on using APIs in the red-bean book which says: Subversion is primarily a set of C libraries, with header (.h) files that live in the subversion/include directory of the source tree. These headers are copied into your system locations (e.g., /usr/local/include) when you build and install Subversion itself from source. These headers represent the entirety of the functions and types meant to be accessible by users of the Subversion libraries. I'd like to use CollabNet Subversion but there doesn't seem to be API binary downloads, and I'd just as soon not build the whole thing if I can avoid it. Considering another approach, I found RapidSVN's C++ API, but it doesn't appear to offer Windows API binaries either and seems to require building SVN (which I would be willing to do as a last choice if RapidSVN's API is higher-level than the stock SVN offering.) Does calling the API from C++ in Windows have to be this much more work compared to using SharpSvn under .NET, or is there something I haven't found that would help me achieve my goal?

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• Problem with sprintf function, last parameters are wrong when written

  - by Apoc

  So I use sprintf sprintf(buffer,"%f|%f|%f|%f|%f|%f|%d|%f|%d", x, y, z, u, v, w, nID,dDistance, nConfig) But when I print the buffer I get the 2 last parameters wrong, they are lets suppose to be 35.0000 and 0 and in the string they are 0.00000 and 10332430 and my buffer is long enough and all the other parameters are good in the string Any idea? Is there a length limit to sprintf or something^ I checked the types of all the numbers and they are right, but what seems to be the problem is the dDistance. When I remove it from the sprint, the nConfig gets the right value in the string, but when I remove nConfig, dDistance still doesn't get the right value. I checked and dDistance is a double. Any idea? Since people don't seem to believe me I did this : char test[255]={0}; int test1 = 2; double test2=35.00; int test3 = 0; sprintf(test,"%d|%f|%d",test1,test2,test3); and I get this in my string: 2|0.000000|1078034432

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• C++ Declarative Parsing Serialization

  - by Martin York

  Looking at Java and C# they manage to do some wicked processing based on special languaged based anotation (forgive me if that is the incorrect name). In C++ we have two problems with this: 1) There is no way to annotate a class with type information that is accessable at runtime. 2) Parsing the source to generate stuff is way to complex. But I was thinking that this could be done with some template meta-programming to achieve the same basic affect as anotations (still just thinking about it). Like char_traits that are specialised for the different types an xml_traits template could be used in a declaritive way. This traits class could be used to define how a class is serialised/deserialized by specializing the traits for the class you are trying to serialize. Example Thoughs: template<typename T> struct XML_traits { typedef XML_Empty Children; }; template<> struct XML_traits<Car> { typedef boost::mpl::vector<Body,Wheels,Engine> Children; }; template<typename T> std::ostream& Serialize(T const&) { // my template foo is not that strong. // but somthing like this. boost::mpl::for_each<typename XML_Traits<T>::Children,Serialize>(data); } template<> std::ostream& Serialize<XML_Empty>(T const&) { /* Do Nothing */ } My question is: Has anybody seen any projects/decumentation (not just XML) out there that uses techniques like this (template meta-programming) to emulate the concept of annotation used in languges like Java and C# that can then be used in code generation (to effectively automate the task by using a declaritive style). At this point in my research I am looking for more reading material and examples.

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• Why aren't my MySQL Group By Hours vs Half Hours files Not displaying same data?

  - by stogdilla

  I need to be able to display data that I have in 15 minute increments in different display types. I have two queries that are giving me trouble. One shows data by half an hour, the other shows data by hour. The only issue is that the data totals change between queries. It's not counting the data that happens between the time frames, only AT the time frames. Ex: There are 5 things that happen at 7:15am. 2 that happen at 7:30am and 4 that show at 7:00am. The 15 minute view displays all of the data. The half hour view displays the data from 7:00am and from 7:30am but ignores the 7:15am. The hour display only shows the 7:00am data Here are my queries: $query="SELECT * FROM data WHERE startDate='$startDate' and queue='$queue' GROUP BY HOUR(start),floor(minute(start)/30)"; and $query="SELECT * FROM data WHERE startDate='$startDate' and queue='$queue' GROUP BY HOUR(start) "; How can I pull out the data in groups like I have but get all the data included? Is the issue the way the data is stored in the mysql table? Currently I have a column with dates (2010-03-29) and a column with times (00:00) Do I need to convert these into something else?

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• How do I make this nested for loop, testing sums of cubes, more efficient?

  - by Brian J. Fink

  I'm trying to iterate through all the combinations of pairs of positive long integers in Java and testing the sum of their cubes to discover if it's a Fibonacci number. I'm currently doing this by using the value of the outer loop variable as the inner loop's upper limit, with the effect being that the outer loop runs a little slower each time. Initially it appeared to run very quickly--I was up to 10 digits within minutes. But now after 2 full days of continuous execution, I'm only somewhere in the middle range of 15 digits. At this rate it may end up taking a whole year just to finish running this program. The code for the program is below: import java.lang.*; import java.math.*; public class FindFib { public static void main(String args[]) { long uLimit=9223372036854775807L; //long maximum value BigDecimal PHI=new BigDecimal(1D+Math.sqrt(5D)/2D); //Golden Ratio for(long a=1;a<=uLimit;a++) //Outer Loop, 1 to maximum for(long b=1;b<=a;b++) //Inner Loop, 1 to current outer { //Cube the numbers and add BigDecimal c=BigDecimal.valueOf(a).pow(3).add(BigDecimal.valueOf(b).pow(3)); System.out.print(c+" "); //Output result //Upper and lower limits of interval for Mobius test: [c*PHI-1/c,c*PHI+1/c] BigDecimal d=c.multiply(PHI).subtract(BigDecimal.ONE.divide(c,BigDecimal.ROUND_HALF_UP)), e=c.multiply(PHI).add(BigDecimal.ONE.divide(c,BigDecimal.ROUND_HALF_UP)); //Mobius test: if integer in interval (floor values unequal) Fibonacci number! if (d.toBigInteger().compareTo(e.toBigInteger())!=0) System.out.println(); //Line feed else System.out.print("\r"); //Carriage return instead } //Display final message System.out.println("\rDone. "); } } Now the use of BigDecimal and BigInteger was delibrate; I need them to get the necessary precision. Is there anything other than my variable types that I could change to gain better efficiency?

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• Auto increment with a Unit Of Work

  - by Derick

  Context I'm building a persistence layer to abstract different types of databases that I'll be needing. On the relational part I have mySQL, Oracle and PostgreSQL. Let's take the following simplified MySQL tables: CREATE TABLE Contact ( ID varchar(15), NAME varchar(30) ); CREATE TABLE Address ( ID varchar(15), CONTACT_ID varchar(15), NAME varchar(50) ); I use code to generate system specific alpha numeric unique ID's fitting 15 chars in this case. Thus, if I insert a Contact record with it's Addresses I have my generated Contact.ID and Address.CONTACT_IDs before committing. I've created a Unit of Work (amongst others) as per Martin Fowler's patterns to add transaction support. I'm using a key based Identity Map in the UoW to track the changed records in memory. It works like a charm for the scenario above, all pretty standard stuff so far. The question scenario comes in when I have a database that is not under my control and the ID fields are auto-increment (or in Oracle sequences). In this case I do not have the db generated Contact.ID beforehand, so when I create my Address I do not have a value for Address.CONTACT_ID. The transaction has not been started on the DB session since all is kept in the Identity Map in memory. Question: What is a good approach to address this? (Avoiding unnecessary db round trips) Some ideas: Retrieve the last ID: I can do a call to the database to retrieve the last Id like: SELECT Auto_increment FROM information_schema.tables WHERE table_name='Contact'; But this is MySQL specific and probably something similar can be done for the other databases. If do this then would need to do the 1st insert, get the ID and then update the children (Address.CONTACT_IDs) – all in the current transaction context.

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• When is factory method better than simple factory and vice versa?

  - by Bruce

  Hi all Working my way through the Head First Design Patterns book. I believe I understand the simple factory and the factory method, but I'm having trouble seeing what advantages factory method brings over simple factory. If an object A uses a simple factory to create its B objects, then clients can create it like this: A a = new A(new BFactory()); whereas if an object uses a factory method, a client can create it like this: A a = new ConcreteA(); // ConcreteA contains a method for instantiating the same Bs that the BFactory above creates, with the method hardwired into the subclass of A, ConcreteA. So in the case of the simple factory, clients compose A with a B factory, whereas with the factory method, the client chooses the appropriate subclass for the types of B it wants. There really doesn't seem to be much to choose between them. Either you have to choose which BFactory you want to compose A with, or you have to choose the right subclass of A to give you the Bs. Under what circumstances is one better than the other? Thanks all!

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• Detecting const-ness of nested type

  - by Channel72

  Normally, if I need to detect whether a type is const I just use boost::is_const. However, I ran into trouble when trying to detect the const-ness of a nested type. Consider the following traits template, which is specialized for const types: template <class T> struct traits { typedef T& reference; }; template <class T> struct traits<const T> { typedef T const& reference; }; The problem is that boost::is_const doesn't seem to detect that traits<const T>::reference is a const type. For example: std::cout << std::boolalpha; std::cout << boost::is_const<traits<int>::reference>::value << " "; std::cout << boost::is_const<traits<const int>::reference>::value << std::endl; This outputs: false false Why doesn't it output false true?

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• Two part question about submitting bluetooth-enabled apps for the iPhone

  - by Kyle

  I have a couple questions about submitting blue-tooth enabled apps on the iPhone. I want to first say that bluetooth is merely an option in the application. The application does not completely rely on bluetooth as there are many modes the user can go in. First, do they require you to have the "peer-peer" key set in UIRequiredDeviceCapabilities even if bluetooth interface options can be disabled or hidden for non-bluetooth enabled devices? Basically, it's just an OPTION in the game and there are many other modes the player can play.. Does Apple not allow you to do that? I'm just curious, because it seems like something they would do. Adding to that, how do you check for it's functionality at runtime? In essence, how do you check UIRequiredDeviceCapabilities at runtime. I'm aware of checking iPhone device types, so would that be a proper way of going about it? I'm also sort of unaware which devices can run bluetooth gamekit, there doesn't seem to be a proper reference at the SDK site, or I'm unable to find it. Thanks for reading! [edit] I can confirm the existance of somebody rejected for submitting a bluetooth enabled app which didn't work on a iPhone 2G.. Of course, they didn't say if that was the MAIN function of the app, though.

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• How would you implement a hashtable in language x?

  - by mk

  The point of this question is to collect a list of examples of hashtable implementations using arrays in different languages. It would also be nice if someone could throw in a pretty detailed overview of how they work, and what is happening with each example. Edit: Why not just use the built in hash functions in your specific language? Because we should know how hash tables work and be able to implement them. This may not seem like a super important topic, but knowing how one of the most used data structures works seems pretty important to me. If this is to become the wikipedia of programming, then these are some of the types of questions that I will come here for. I'm not looking for a CS book to be written here. I could go pull Intro to Algorithms off the shelf and read up on the chapter on hash tables and get that type of info. More specifically what I am looking for are code examples. Not only for me in particular, but also for others who would maybe one day be searching for similar info and stumble across this page. To be more specific: If you had to implement them, and could not use built-in functions, how would you do it? You don't need to put the code here. Put it in pastebin and just link it.

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• How to test if a doctrine records has any relations that are used

  - by murze

  Hi, I'm using a doctrine table that has several optional relations (of types Doctrine_Relation_Association and Doctrine_Relation_ForeignKey) with other tables. How can I test if a record from that table has connections with records from the related table. Here is an example to make my question more clear. Assume that you have a User and a user has a many to many relation with Usergroups and a User can have one Userrole How can I test if a give user is part of any Usergroups or has a role. The solution starts I believe with $relations = Doctrine_Core::getTable('User')->getRelations(); $user = Doctrine_Core::getTable('User')->findOne(1); foreach($relations as $relation) { //here should go a test if the user has a related record for this relation if ($relation instanceof Doctrine_Relation_Association) { //here the related table probably has more then one foreign key (ex. user_id and group_id) } if ($relation instanceof Doctrine_Relation_ForeignKey) { //here the related table probably has the primary key of this table (id) as a foreign key (user_id) } } //true or false echo $result I'm looking for a general solution that will work no matter how many relations there are between user and other tables. Thanks!

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