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  • Swing and handling threads

    - by James P.
    There's a couple questions here on StackOverflow on the subject of threading with the Swing api but things still aren't clear. What is the issue with the EDT, what is the proper way to initiate a Thread with Swing and in what cases should it be used? P.S: Any sources in terms of good practises would be appreciated.

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  • Strange exception phenomenon in Windows 7

    - by Level 2
    I spot some interesting articles about exception handle in CodeProject http://www.codeproject.com/KB/cpp/seexception.aspx After reading, I decided to do some experiment. The first time I try to execute the following code char *p; p[0] = 0; The program died without question. But After several times when I executed the same problem binary code, it magically did fine. Even the following code is doing well. Any clue or explanation? char *p p[1000] = 'd'; cout<<p[1000]<<endl; My O/S is Windows 7 64bit and compiler is VS2008 rc1.

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  • Ignoring (serious) errors to keep the program alive?

    - by SQuirreL bites
    One of the main things I wanted to achieve in my experimental programming language was: When errors occur (Syntax, Name, Type, etc.) keep the program running, no matter how serious or devastating it is. I know that this is probably very bad, but I just wanted something that doesn't kill itself on every error - I find it interesting what happens when a serious error occurs but the program continues. Does this "paradigm" have a name? I mean expect for How bad is it to do the above? Are there programs in use out there that just follow: "Hey, this is a fatal, unexpected error - but you know what? I don't care!"?

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  • why cannot use uncaught_exception in dtor?

    - by camino
    Hi , Herb Sutter in his article http://www.gotw.ca/gotw/047.htm pointed out that we cannot use uncaught_exception in desturctor function, // Why the wrong solution is wrong // U::~U() { try { T t; // do work } catch( ... ) { // clean up } } If a U object is destroyed due to stack unwinding during to exception propagation, T::~T will fail to use the "code that could throw" path even though it safely could. but I write a test program, and T::~T in fact didn't use the "code that could throw" #include <exception> #include <iostream> using namespace std; class T { public: ~T() { if( !std::uncaught_exception() ) { cout<<"can throw"<<endl; throw 1; } else { cout<<"cannot throw"<<endl; } } }; struct U { ~U() { try { T t; } catch( ... ) { } } }; void f() { U u; throw 2; } int main() { try { f(); } catch(...) {} } output is : cannot throw did I miss something? Thanks

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  • When to use try/catch

    - by coffeeaddict
    I'm always finding myself wanting to put a try/catch around the lets say Business Layer methods. But I feel though that I don't need a try/catch if I'm simply rethrowing it up to the Presentation Layer. Is that right? I should not be rethrowing an exception from code that's wrapped in a try/catch in a BL method and should be letting the caller which would be from the Presentation Layer code be using a try/catch to handle it there? The BL method will throw an error without the try/catch anyway..the compiler will. So it wouldn't make sense to use a try/catch in a BL method that's to be consumed by a layer higher up correct?

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  • Are there SqlExceptions which throw but commit their data anyway?

    - by Jonn
    I've recently encountered the error: System.Data.SqlClient.SqlException: The transaction log for database 'mydatabase' is full. To find out why space in the log cannot be reused, see the log_reuse_wait_desc column in sys.databases on one of my windows services. It's supposed to retry after catching an Sql Exception, what I didn't expect was that it seemed like the data was still going through (I'm using an SqlBulkCopy btw) regardless of it throwing an exception. I've never encountered this scenario before. I'd like to know if there are other scenarios where such a thing like this might happen, and if this thing is entirely possible at all in the first place? PS. If anyone knows the error code to the above exception, that would help a great deal as well.

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  • Handling null values with PowerShell dates

    - by Tim Ferrill
    I'm working on a module to pull data from Oracle into a PowerShell data table, so I can automate some analysis and perform various actions based on the results. Everything seems to be working, and I'm casting columns into specific types based on the column type in Oracle. The problem I'm having has to do with null dates. I can't seem to find a good way to capture that a date column in Oracle has a null value. Is there any way to cast a [datetime] as null or empty?

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  • How to further improve error messages in Scala parser-combinator based parsers?

    - by rse
    I've coded a parser based on Scala parser combinators: class SxmlParser extends RegexParsers with ImplicitConversions with PackratParsers { [...] lazy val document: PackratParser[AstNodeDocument] = ((procinst | element | comment | cdata | whitespace | text)*) ^^ { AstNodeDocument(_) } [...] } object SxmlParser { def parse(text: String): AstNodeDocument = { var ast = AstNodeDocument() val parser = new SxmlParser() val result = parser.parseAll(parser.document, new CharArrayReader(text.toArray)) result match { case parser.Success(x, _) => ast = x case parser.NoSuccess(err, next) => { tool.die("failed to parse SXML input " + "(line " + next.pos.line + ", column " + next.pos.column + "):\n" + err + "\n" + next.pos.longString) } } ast } } Usually the resulting parsing error messages are rather nice. But sometimes it becomes just sxml: ERROR: failed to parse SXML input (line 32, column 1): `"' expected but `' found ^ This happens if a quote characters is not closed and the parser reaches the EOT. What I would like to see here is (1) what production the parser was in when it expected the '"' (I've multiple ones) and (2) where in the input this production started parsing (which is an indicator where the opening quote is in the input). Does anybody know how I can improve the error messages and include more information about the actual internal parsing state when the error happens (perhaps something like a production rule stacktrace or whatever can be given reasonably here to better identify the error location). BTW, the above "line 32, column 1" is actually the EOT position and hence of no use here, of course.

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  • Implication of (not) rethrowing exception after logging

    - by dotnetdev
    Hi, In a team environment, if I handle an exception (like so): protected void Page_Load(object sender, EventArgs e) { this.exTest(); } public void exTest() { try { throw new Exception("sjsj"); } catch (Exception ex) { string s = ex.Message; throw; } } What is the implication of not rethrowing the exception (throw)? Even without the keyword the custom error settings in web.config are used (redirection to specified page). Thanks

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  • In Asp.net (c#) i'm not able to catch any exception properly????

    - by Anand
    In Asp.net (c#),i'm not able to catch exception(FileNotFoundException) properly... i don't know the reason..Actually File s not there..But catch statement fails to catch the exception.. here is the code.. try { System.Drawing.Image imgg1 = System.Drawing.Image.FromFile(Server.MapPath("").ToString() + "\\images\\img1.jpg"); } catch (FileNotFoundException) { Response.Write("<script>alert('Please Select and upload Student's Photo');</script>"); }

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  • Exception message (Python 2.6)

    - by TurboJupi
    If I want to open binary file (in Python 2.6), that doesn't exists, program exits with an error and prints this: Traceback (most recent call last): File "C:\Python_tests\Exception_Handling\src\exception_handling.py", line 4, in <module> pkl_file = open('monitor.dat', 'rb') IOError: [Errno 2] No such file or directory: 'monitor.dat' I can handle this with 'try-except', like: try: pkl_file = open('monitor.dat', 'rb') monitoring_pickle = pickle.load(pkl_file) pkl_file.close() except Exception: print 'No such file or directory' Does anybody know, how could I, in caught Exception, print the following line? File "C:\Python_tests\Exception_Handling\src\exception_handling.py", line 11, in <module> pkl_file = open('monitor.dat', 'rb') So, program would not exits, and I would have useful information.

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  • Firing PropertyChanged event in a complex, nested type in WPF

    - by John
    Hey I have a question about the PropertyChanged vent firing in WPF whne it is used in a complex type. I have a class called DataStore and a list of Departments (an ObservableCollection), and each department again has a list of Products. Properties in the Product class that are changed also affect properties in the Department and DataStore class. How does each Product notify the Department it belongs to, and the DataStore (which is the mother class of all) that one or more of its properties have changed their values? Example: a product has a property NumberSoldToday and is bound. The Department has a property called TotalNumberOfProductsSold: public int TotalNumberOfProductsSold { get { int result = 0; foreach(Product p in this.products) result += p.NumberSoldToday; return result; } } And the data store has a property TotalProductsSold (for all departments): public int TotalProductsSold { get { int result = 0; foreach(Product p in this.deparments) result += p.TotalNumberOfProductsSold; return result; } } If all these properties are bound, and the innermost property changes, it must somehow notify that the value of the other 2 changed as well. How? The only way I can see this happening is to hook up the PropertyChanged event in each class. Th event must also fire when deleting, adding to the collection of products and deparments, respectively. Is there a better, more clever way to do this?

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  • Handling primary key duplicates in a data warehouse load

    - by Meff
    I'm currently building an ETL system to load a data warehouse from a transactional system. The grain of my fact table is the transaction level. In order to ensure I don't load duplicate rows I've put a primary key on the fact table, which is the transaction ID. I've encountered a problem with transactions being reversed - In the transactional database this is done via a status, which I pick up and I can work out if the transaction is being done, or rolled back so I can load a reversal row in the warehouse. However, the reversal row will have the same transaction ID and so I get a primary key violation. I've solved this for now by negating the primary key, so transaction ID 1 would be a payment, and transaction ID -1 (In the warehouse only) would be the reversal. I have considered an alternative of generating a BIT column, where 0 is normal and 1 is reversal, then making the PK the transaction ID and the BIT column. My question is, is this a good practice, and has anyone else encountered anything like this? For reference, this is a payment processing system, so values will not be modified, so there will only ever be transactions and reversals.

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  • Exceptions from WCF

    - by adrianm
    What exceptions can be thrown from a WCF client? I usually catch CommunicationFaultedException, CommunicationException, TimoutException and some other but from time to time new ones occur, e.g. most recently QuotaExceededException There is no common base to catch (except Exception) so does anyone have a complete list?

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  • Porting Windows C++ to Standard (Linux) C++ - WSAGetLastError()

    - by Donal Rafferty
    I am currently porting some Windows mobile C++ code to standard C++. So I am trying to find alternatives for windows specific functions. I have had very little luck in finding a standard C++ function that can help me replace the WSAGetLastError() windows specific function. WSAGetLastError() returns error numbers for errors that occur with sockets in windows. So I was wondering if anyone was aware of a way to replace this function in standard c++? A way to get different error numbers for different outcomes of connecting/dissconection a socket would be sufficent.

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  • following code comipling perfectly but showing runtime error . why?

    - by user323422
    //sample.h int calci(int &value) { if(value < 20) throw value; else return value; } class XYX { int m_x; public: XYZ(int &x)try:m_x(a-calci(x)) { }catch (int &a) {} }; class ABC { int m_a; public: ABC():m_a(0) { } void foo() { XYZ xyz(10); } }; int main() { ABC abc; abc.foo(); } //if i replace foo() with following code then it works well void foo() { try{ XYZ xyz(10); }catch(...){} }

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  • What is a good "Error Checking" Pattern (Java)?

    - by Jack
    I'll explain what I mean by input error checking. Say you have a function doSomething(x). If the function completes successfully doSomething does something and returns nothing. However, if there are errors I'd like to be notified. That is what I mean by error checking. I'm looking for, in general, the best way to check for errors. I've thought of the following solutions, each with a potential problem. Flag error checking. If doSomething(x) completes successfully return null. Otherwise, it returns a boolean or an error string. Problem: Side effects. Throwing an exception. Throw an exception if doSomething(x) encounters an error. Problem: If you are performing error checking for parameters only, throwing an IllegalArgumentExceptionseems inappropriate. Validating input prior to function call. If the error checking is only meant for the parameters of the function, then you can call a validator function before calling the doSomething(x) function. Problem: What if a client of the class forgets to call the validator function before calling doSomething(x)? I often encounter this problem and any help or a point in the right direction would be much appreciated.

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  • How to prevent users from typing incorrect inputs ?

    - by ZaZu
    Hello, I want the program to loop a scan function if the user types anything else other than numbers.. My code is : do{ printf("Enter rows\n"); scanf("%d",&row); }while(row>='a' && row<='z'); but this code doesnt work .. I keep getting an error when typing in a letter. I tried manipulating around it and the whole thing loops infinitely ... What am I doing wrong ? Please help thanks !

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