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  • Performance - FunctionCall vs Event vs Action vs Delegate

    - by hwcverwe
    Currently I am using Microsoft Sync Framework to synchronize databases. I need to gather information per record which is inserted/updated/deleted by Microsoft Sync Framework and do something with this information. The sync speed can go over 50.000 records per minute. So that means my additional code need to be very lightweight otherwise it will be a huge performance penalty. Microsoft Sync Framework raises an SyncProgress event for each record. I am subscribed to that code like this: // Assembly1 SyncProvider.SyncProgress += OnSyncProgress; // .... private void OnSyncProgress(object sender, DbSyncProgressEventArgs e) { switch (args.Stage) { case DbSyncStage.ApplyingInserts: // MethodCall/Delegate/Action<>/EventHandler<> => HandleInsertedRecordInformation // Do something with inserted record info break; case DbSyncStage.ApplyingUpdates: // MethodCall/Delegate/Action<>/EventHandler<> => HandleUpdatedRecordInformation // Do something with updated record info break; case DbSyncStage.ApplyingDeletes: // MethodCall/Delegate/Action<>/EventHandler<> => HandleDeletedRecordInformation // Do something with deleted record info break; } } Somewhere else in another assembly I have three methods: // Assembly2 public class SyncInformation { public void HandleInsertedRecordInformation(...) {...} public void HandleUpdatedRecordInformation(...) {...} public void HandleInsertedRecordInformation(...) {...} } Assembly2 has a reference to Assembly1. So Assembly1 does not know anything about the existence of the SyncInformation class which need to handle the gathered information. So I have the following options to trigger this code: use events and subscribe on it in Assembly2 1.1. EventHandler< 1.2. Action< 1.3. Delegates using dependency injection: public class Assembly2.SyncInformation : Assembly1.ISyncInformation Other? I know the performance depends on: OnSyncProgress switch using a method call, delegate, Action< or EventHandler< Implementation of SyncInformation class I currently don't care about the implementation of the SyncInformation class. I am mainly focused on the OnSyncProgress method and how to call the SyncInformation methods. So my questions are: What is the most efficient approach? What is the most in-efficient approach? Is there a better way than using a switch in OnSyncProgress?

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  • How to make MySQL utilize available system resources, or find "the real problem"?

    - by anonymous coward
    This is a MySQL 5.0.26 server, running on SuSE Enterprise 10. This may be a Serverfault question. The web user interface that uses these particular queries (below) is showing sometimes 30+, even up to 120+ seconds at the worst, to generate the pages involved. On development, when the queries are run alone, they take up to 20 seconds on the first run (with no query cache enabled) but anywhere from 2 to 7 seconds after that - I assume because the tables and indexes involved have been placed into ram. From what I can tell, the longest load times are caused by Read/Update Locking. These are MyISAM tables. So it looks like a long update comes in, followed by a couple 7 second queries, and they're just adding up. And I'm fine with that explanation. What I'm not fine with is that MySQL doesn't appear to be utilizing the hardware it's on, and while the bottleneck seems to be the database, I can't understand why. I would say "throw more hardware at it", but we did and it doesn't appear to have changed the situation. Viewing a 'top' during the slowest times never shows much cpu or memory utilization by mysqld, as if the server is having no trouble at all - but then, why are the queries taking so long? How can I make MySQL use the crap out of this hardware, or find out what I'm doing wrong? Extra Details: On the "Memory Health" tab in the MySQL Administrator (for Windows), the Key Buffer is less than 1/8th used - so all the indexes should be in RAM. I can provide a screen shot of any graphs that might help. So desperate to fix this issue. Suffice it to say, there is legacy code "generating" these queries, and they're pretty much stuck the way they are. I have tried every combination of Indexes on the tables involved, but any suggestions are welcome. Here's the current Create Table statement from development (the 'experimental' key I have added, seems to help a little, for the example query only): CREATE TABLE `registration_task` ( `id` varchar(36) NOT NULL default '', `date_entered` datetime NOT NULL default '0000-00-00 00:00:00', `date_modified` datetime NOT NULL default '0000-00-00 00:00:00', `assigned_user_id` varchar(36) default NULL, `modified_user_id` varchar(36) default NULL, `created_by` varchar(36) default NULL, `name` varchar(80) NOT NULL default '', `status` varchar(255) default NULL, `date_due` date default NULL, `time_due` time default NULL, `date_start` date default NULL, `time_start` time default NULL, `parent_id` varchar(36) NOT NULL default '', `priority` varchar(255) NOT NULL default '9', `description` text, `order_number` int(11) default '1', `task_number` int(11) default NULL, `depends_on_id` varchar(36) default NULL, `milestone_flag` varchar(255) default NULL, `estimated_effort` int(11) default NULL, `actual_effort` int(11) default NULL, `utilization` int(11) default '100', `percent_complete` int(11) default '0', `deleted` tinyint(1) NOT NULL default '0', `wf_task_id` varchar(36) default '0', `reg_field` varchar(8) default '', `date_offset` int(11) default '0', `date_source` varchar(10) default '', `date_completed` date default '0000-00-00', `completed_id` varchar(36) default NULL, `original_name` varchar(80) default NULL, PRIMARY KEY (`id`), KEY `idx_reg_task_p` (`deleted`,`parent_id`), KEY `By_Assignee` (`assigned_user_id`,`deleted`), KEY `status_assignee` (`status`,`deleted`), KEY `experimental` (`deleted`,`status`,`assigned_user_id`,`parent_id`,`date_due`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 And one of the ridiculous queries in question: SELECT users.user_name assigned_user_name, registration.FIELD001 parent_name, registration_task.status status, registration_task.date_modified date_modified, registration_task.date_due date_due, registration.FIELD240 assigned_wf, if(LENGTH(registration_task.description)>0,1,0) has_description, registration_task.* FROM registration_task LEFT JOIN users ON registration_task.assigned_user_id=users.id LEFT JOIN registration ON registration_task.parent_id=registration.id where (registration_task.status != 'Completed' AND registration.FIELD001 LIKE '%' AND registration_task.name LIKE '%' AND registration.FIELD060 LIKE 'GN001472%') AND registration_task.deleted=0 ORDER BY date_due asc LIMIT 0,20; my.cnf - '[mysqld]' section. [mysqld] port = 3306 socket = /var/lib/mysql/mysql.sock skip-locking key_buffer = 384M max_allowed_packet = 100M table_cache = 2048 sort_buffer_size = 2M net_buffer_length = 100M read_buffer_size = 2M read_rnd_buffer_size = 160M myisam_sort_buffer_size = 128M query_cache_size = 16M query_cache_limit = 1M EXPLAIN above query, without additional index: +----+-------------+-------------------+--------+--------------------------------+----------------+---------+------------------------------------------------+---------+-----------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------------------+--------+--------------------------------+----------------+---------+------------------------------------------------+---------+-----------------------------+ | 1 | SIMPLE | registration_task | ref | idx_reg_task_p,status_assignee | idx_reg_task_p | 1 | const | 1067354 | Using where; Using filesort | | 1 | SIMPLE | registration | eq_ref | PRIMARY,gbl | PRIMARY | 8 | sugarcrm401.registration_task.parent_id | 1 | Using where | | 1 | SIMPLE | users | ref | PRIMARY | PRIMARY | 38 | sugarcrm401.registration_task.assigned_user_id | 1 | | +----+-------------+-------------------+--------+--------------------------------+----------------+---------+------------------------------------------------+---------+-----------------------------+ EXPLAIN above query, with 'experimental' index: +----+-------------+-------------------+--------+-----------------------------------------------------------+------------------+---------+------------------------------------------------+--------+-----------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------------------+--------+-----------------------------------------------------------+------------------+---------+------------------------------------------------+--------+-----------------------------+ | 1 | SIMPLE | registration_task | range | idx_reg_task_p,status_assignee,NewIndex1,tcg_experimental | tcg_experimental | 259 | NULL | 103345 | Using where; Using filesort | | 1 | SIMPLE | registration | eq_ref | PRIMARY,gbl | PRIMARY | 8 | sugarcrm401.registration_task.parent_id | 1 | Using where | | 1 | SIMPLE | users | ref | PRIMARY | PRIMARY | 38 | sugarcrm401.registration_task.assigned_user_id | 1 | | +----+-------------+-------------------+--------+-----------------------------------------------------------+------------------+---------+------------------------------------------------+--------+-----------------------------+

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  • Newbie jQuery question: Need slideshow to rotate automatically, not just when clicking navigation.

    - by Justin
    Hi everyone, This is my first post, so please forgive me if this question has been asked a million times. I'm a self professed jQuery hack and I need a little guidance on taking this script I found and adapting it to my needs. Anyway, what I'm making is an image slide show with navigation. The script I found does this, but does not automatically cycle through the images. I'm using jQuery 1.3.2 and would rather stick with that than using the newer library. I would also prefer to edit what is already here rather than start from scratch. Anywho, here's the html: <div id="myslide"> <div class="cover"> <div class="mystuff"> <img alt="&nbsp;" src="http://www.mfhc.com/wp/wp-content/uploads/2010/05/current_Denver-skyline.jpg" /> </div> <div class="mystuff"> <img alt="&nbsp;" src="http://www.mfhc.com/wp/wp-content/uploads/2010/05/pepsi_center-IS42RF-0D111C.jpg" /> </div> <div class="mystuff"> <img alt="&nbsp;" src="http://www.mfhc.com/wp/wp-content/uploads/2010/05/columbine-2689820469_D1104.jpg" /> </div> <div class="mystuff"> <img alt="&nbsp;" src="http://www.mfhc.com/wp/wp-content/uploads/2010/05/ist2_10460354-RedRocks.jpg" /> </div> </div> <!-- end of div cover --> </div> <!-- end of div myslide --> And here's the jQuery: <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script> <script type="text/JavaScript"> $(document).ready(function (){ $('#button a').click(function(){ var integer = $(this).attr('rel'); $('#myslide .cover').css({left:-820*(parseInt(integer)-1)}).hide().fadeIn(); /*----- Width of div #mystuff (here 820) ------ */ $('#button a').each(function(){ $(this).removeClass('active'); if($(this).hasClass('button'+integer)){ $(this).addClass('active')} }); }); }); </script> Here's where I got the script: http://www.webdeveloperjuice.com/2010/04/07/create-lightweight-jquery-fade-manual-slideshow/ Again, if this question is too basic for this site please let me know and possibly provide a reference link or two. Thanks a ton!

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  • Learning C, would appreciate input on why this solution works.

    - by Keifer
    This is literally the first thing I've ever written in C, so please feel free to point out all it's flaws. :) My issue, however is this: if I write the program the way I feel is cleanest, I get a broken program: #include <sys/queue.h> #include <stdlib.h> #include <stdio.h> #include <string.h> /* Removed prototypes and non related code for brevity */ int main() { char *cmd = NULL; unsigned int acct = 0; int amount = 0; int done = 0; while (done==0) { scanf ("%s %u %i", cmd, &acct, &amount); if (strcmp (cmd, "exit") == 0) done = 1; else if ((strcmp (cmd, "dep") == 0) || (strcmp (cmd, "deb") == 0)) debit (acct, amount); else if ((strcmp (cmd, "wd") == 0) || (strcmp (cmd, "cred") == 0)) credit (acct, amount); else if (strcmp (cmd, "fee") == 0) service_fee(acct, amount); else printf("Invalid input!\n"); } return(0); } void credit(unsigned int acct, int amount) { } void debit(unsigned int acct, int amount) { } void service_fee(unsigned int acct, int amount) { } As it stands, the above generates no errors at compile, but gives me a segfault when ran. I can fix this by changing the program to pass cmd by reference when calling scanf and strcmp. The segfault goes away and is replaced by warnings for each use of strcmp at compile time. Despite the warnings, the affected code works. warning: passing arg 1 of 'strcmp' from incompatible pointer type As an added bonus, modifying the scanf and strcmp calls allows the program to progress far enough to execute return(0), at which point the thing crashes with an Abort trap. If I swap out return(0) for exit(0) then everything works as expected. This leaves me with two questions: why was the original program wrong? How can I fix it better than I have? The bit about needing to use exit instead of return has me especially baffled.

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  • Could not load file or assembly ... or one of its dependencies. An attempt was made to load a progra

    - by Dan
    I am getting the following error message when compiling or attempting to run my application on Windows 7 64 bit. I've scoured the internet and many people have the same error message however none of the solutions address my problem or situation. Using VS 2010. Error 38 Could not load file or assembly 'file:///D:/Projects/Windows Projects/Weld/Components/FileAttachments/FileAttachments/FileAttachments/bin/x86/Debug/FileAttaching.dll' or one of its dependencies. An attempt was made to load a program with an incorrect format. Line 1212, position 5. D:\Projects\Windows Projects\Weld\Weld\Weld.UI\frmMain.resx 1212 5 Weld.UI Ok, so I have 2 projects a UI project and a FileAttachment project. UI project has a reference to FileAttachment project. When I compile UI project in "Any CPU" mode everything works fine and it runs. I assume 'Any CPU' will run in 64bit mode when I compile as that is the platform I am using. I want to run/compile as x86 so I try to do that, so I change configuration for all projects to x86 and verify that these configurations are compiling to x86. I compile and get the error as stated above. I find it odd that it compiles and works fine in 64bit but not 32bit. However when compiled and deployed to users as 'Any CPU', if these users have x86 it still works for them no problem. I just can't compile or run as x86 on my PC. Again, I can compile as Any CPU and deploy to a 32bit PC no problem. Neither project are referencing any 64bit only dlls. Both projects are verified to be targetting 32bit dll's and .NET Framework assemblies. I need to compile and run this locally under 32bit mode. I need JIT edit/continue among other things. Here is the line of code in the resx file that is causing the problem: </data> <data name="Appearance17.Image" type="System.Drawing.Bitmap, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64"> <value> The resx file is verified to be generated for .NET 2.0 amnd is only referencing .NET 2.0 assemblies and not .NET 4.0 versions. Any ideas here? I've searched the net and have found hundreds of people with the same error message but a different problem.

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  • Do classes which have a vector has a member have memory issues

    - by user263766
    I am just starting out C++, so sorry if this is a dumb question. I have a class Braid whose members are vectors. I have not written an assignment operator. When I do a lot of assignments to an object of the type Braid, I run into memory issues :- 0 0xb7daff89 in _int_malloc () from /lib/libc.so.6 #1 0xb7db2583 in malloc () from /lib/libc.so.6 #2 0xb7f8ac59 in operator new(unsigned int) () from /usr/lib/libstdc++.so.6 #3 0x0804d05e in __gnu_cxx::new_allocator<int>::allocate (this=0xbf800204, __n=1) at /usr/lib/gcc/i686-pc-linux-gnu/4.4.3/../../../../include/c++/4.4.3/ext/new_allocator.h:89 #4 0x0804cb0e in std::_Vector_base<int, std::allocator<int> >::_M_allocate (this=0xbf800204, __n=1) at /usr/lib/gcc/i686-pc-linux-gnu/4.4.3/../../../../include/c++/4.4.3/bits/stl_vector.h:140 #5 0x0804c086 in _Vector_base (this=0xbf800204, __n=1, __a=...) at /usr/lib/gcc/i686-pc-linux-gnu/4.4.3/../../../../include/c++/4.4.3/bits/stl_vector.h:113 #6 0x0804b4b7 in vector (this=0xbf800204, __x=...) at /usr/lib/gcc/i686-pc-linux-gnu/4.4.3/../../../../include/c++/4.4.3/bits/stl_vector.h:242 #7 0x0804b234 in Braid (this=0xbf800204) at braid.h:13 #8 0x080495ed in Braid::cycleBraid (this=0xbf8001b4) at braid.cpp:191 #9 0x080497c6 in Braid::score (this=0xbf800298, b=...) at braid.cpp:251 #10 0x08049c46 in Braid::evaluateMove (this=0xbf800468, move=1, pos=0, depth=2, b=...) I suspect that these memory issues are because the vectors are getting resized. What I want to know is whether objects of type Braid automatically expand when its members expand? he code I am writing is really long so I will post the section which is causing the problems. Here is the relevant section of the code :- class Braid { private : vector<int> braid; //Stores the braid. int strands; vector < vector<bool> > history; vector < vector<bool> > CM; public : Braid () : strands(0) {} Braid operator * (Braid); Braid* inputBraid(int,vector<int>); int printBraid(); int printBraid(vector<vector<int>::iterator>); vector<int>::size_type size() const; ..... ..... } Here is the function which causes the issue :- int Braid::evaluateMove(int move,int pos,int depth,Braid b) { int netscore = 0; Braid curr(*this); curr = curr.move(move,pos); netscore += curr.score(b); while(depth > 1) { netscore += curr.evaluateMove(1,0,depth,b); netscore += curr.evaluateMove(2,0,depth,b); for(int i = 0; i < braid.size();++i) { netscore += curr.evaluateMove(3,i,depth,b); netscore += curr.evaluateMove(4,i,depth,b); netscore += curr.evaluateMove(5,i,depth,b); curr = curr.cycleBraid(); netscore += curr.evaluateMove(6,0,depth,b); } --depth; } return netscore; }

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  • Xcode App Crash-When connecting to the ODATA services [on hold]

    - by user3685677
    Can someone help me resolving the following issue: When trying to connect from iPad app to SAP ECC system through ODATA channel services via SUP, it is allowing me to login for the first time and could retrieve the data successfully from SAP system. But when I logout and try logging in again with the same session, application gets crashed. Below is the crash report for your reference. I am using SDM Parser to connect the SAP system. SDMODataServiceDocumentParser *sdmDocParser = [[SDMODataServiceDocumentParser alloc] init]; [sdmDocParser parse:aServiceDocument]; m_serviceDocument = sdmDocParser.serviceDocument; //Load the object with metadata xml: SDMODataMetaDocumentParser *sdmMetadataParser = [[SDMODataMetaDocumentParser alloc] initWithServiceDocument:m_serviceDocument]; [sdmMetadataParser parse:aMetadata]; After initiated the service, setting the URL. [service setServiceDocumentUrl:m_serviceDocumentURL]; Using SDMconnectivityhelper to connect the URL id<SDMRequesting> serviceDocumentRequest2 = [connectivityHelper executeBasicSyncRequestWithQuery3:[[ODataQuery alloc]initWithURL:[NSURL URLWithString:encodedStrUrl]]] ; - (id <SDMRequesting>)executeBasicSyncRequestWithQuery3:(ODataQuery *)aQuery { id<SDMRequesting> request = [self createRequestWithQuery:aQuery]; [request setTimeOutSeconds:TIMEOUT_SEC]; [request setRequestMethod:@"GET"]; [request addRequestHeader:@"Content-Type" value:@"application/xml"]; [request startSynchronous];**[App getting CRASH in this line]** return request; } - (id <SDMRequesting>)createRequestWithQuery:(ODataQuery *)aQuery { if (isSUPMode) { [SDMRequestBuilder setRequestType:SUPRequestType]; } else { [SDMRequestBuilder setRequestType:HTTPRequestType]; } id <SDMRequesting> request = [SDMRequestBuilder requestWithURL:aQuery.URL]; request.username = self.username; request.password = self.password; return request; } Crash Report:- Incident Identifier: 347511BA-5F7F-45D4-8662-D5DCD2F88EA7 CrashReporter Key: 9a4d38cf19b1a94476eb6b2170d4f56678d6ca60 Hardware Model: iPad3,4 Path: /var/mobile/Applications/F38AD64F-03F8-4A21- Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Subtype: KERN_INVALID_ADDRESS at 0x00000000 Triggered by Thread: 0 Thread 0 Crashed: 0 libsystem_platform.dylib 0x393a94c0 _platform_memmove$VARIANT $Swift + 160 1 Eby Sales Order 0x0015a2c8 0xb7000 + 668360 2 Eby Sales Order 0x0015a8b8 0xb7000 + 669880 3 Eby Sales Order 0x003331ee 0xb7000 + 2605550 4 Eby Sales Order 0x0031856e 0xb7000 + 2495854 5 Eby Sales Order 0x00338454 0xb7000 + 2626644 6 Eby Sales Order 0x000e6ad8 0xb7000 + 195288 7 Eby Sales Order 0x000e99a0 0xb7000 + 207264 8 Eby Sales Order 0x000ea442 0xb7000 + 209986 9 Eby Sales Order 0x000eb0d6 0xb7000 + 213206 10 Eby Sales Order 0x000c13d0 0xb7000 + 41936 11 Foundation 0x2ec93112 __NSFireDelayedPerform + 410 12 CoreFoundation 0x2e27ef4c __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 12 13 CoreFoundation 0x2e27eb66 __CFRunLoopDoTimer + 790 14 CoreFoundation 0x2e27ceee __CFRunLoopRun + 1214 15 CoreFoundation 0x2e1e7764 CFRunLoopRunSpecific + 520 16 CoreFoundation 0x2e1e7546 CFRunLoopRunInMode + 102 17 GraphicsServices 0x331216ce GSEventRunModal + 134 18 UIKit 0x30b4688c UIApplicationMain + 1132 19 Eby Sales Order 0x000bd8da 0xb7000 + 26842 20 Eby Sales Order 0x000bd89c 0xb7000 + 26780

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  • Sorting a list of numbers with modified cost

    - by David
    First, this was one of the four problems we had to solve in a project last year and I couldn’t find a suitable algorithm so we handle in a brute force solution. Problem: The numbers are in a list that is not sorted and supports only one type of operation. The operation is defined as follows: Given a position i and a position j the operation moves the number at position i to position j without altering the relative order of the other numbers. If i j, the positions of the numbers between positions j and i - 1 increment by 1, otherwise if i < j the positions of the numbers between positions i+1 and j decreases by 1. This operation requires i steps to find a number to move and j steps to locate the position to which you want to move it. Then the number of steps required to move a number of position i to position j is i+j. We need to design an algorithm that given a list of numbers, determine the optimal (in terms of cost) sequence of moves to rearrange the sequence. Attempts: Part of our investigation was around NP-Completeness, we make it a decision problem and try to find a suitable transformation to any of the problems listed in Garey and Johnson’s book: Computers and Intractability with no results. There is also no direct reference (from our point of view) to this kind of variation in Donald E. Knuth’s book: The art of Computer Programing Vol. 3 Sorting and Searching. We also analyzed algorithms to sort linked lists but none of them gives a good idea to find de optimal sequence of movements. Note that the idea is not to find an algorithm that orders the sequence, but one to tell me the optimal sequence of movements in terms of cost that organizes the sequence, you can make a copy and sort it to analyze the final position of the elements if you want, in fact we may assume that the list contains the numbers from 1 to n, so we know where we want to put each number, we are just concerned with minimizing the total cost of the steps. We tested several greedy approaches but all of them failed, divide and conquer sorting algorithms can’t be used because they swap with no cost portions of the list and our dynamic programing approaches had to consider many cases. The brute force recursive algorithm takes all the possible combinations of movements from i to j and then again all the possible moments of the rest of the element’s, at the end it returns the sequence with less total cost that sorted the list, as you can imagine the cost of this algorithm is brutal and makes it impracticable for more than 8 elements. Our observations: n movements is not necessarily cheaper than n+1 movements (unlike swaps in arrays that are O(1)). There are basically two ways of moving one element from position i to j: one is to move it directly and the other is to move other elements around i in a way that it reaches the position j. At most you make n-1 movements (the untouched element reaches its position alone). If it is the optimal sequence of movements then you didn’t move the same element twice.

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  • How can I link two Java serialised objects back together?

    - by Kidburla
    Sometimes (quite a lot, actually) we get a situation in Java where two objects are pointing to the same thing. Now if we serialise these separately it is quite appropriate that the serialised forms have separate copies of the object as it should be possible to open one without the other. However if we now deserialise them both, we find that they are still separated. Is there any way to link them back together? Example follows. public class Example { private static class ContainerClass implements java.io.Serializable { private ReferencedClass obj; public ReferencedClass get() { return obj; } public void set(ReferencedClass obj) { this.obj = obj; } } private static class ReferencedClass implements java.io.Serializable { private int i = 0; public int get() { return i; } public void set(int i) { this.i = i; } } public static void main(String[] args) throws Exception { //Initialise the classes ContainerClass test1 = new ContainerClass(); ContainerClass test2 = new ContainerClass(); ReferencedClass ref = new ReferencedClass(); //Make both container class point to the same reference test1.set(ref); test2.set(ref); //This does what we expect: setting the integer in one (way of accessing the) referenced class sets it in the other one test1.get().set(1234); System.out.println(Integer.toString(test2.get().get())); //Now serialise the container classes java.io.ObjectOutputStream os = new java.io.ObjectOutputStream(new java.io.FileOutputStream("C:\\Users\\Public\\test1.ser")); os.writeObject(test1); os.close(); os = new java.io.ObjectOutputStream(new java.io.FileOutputStream("C:\\Users\\Public\\test2.ser")); os.writeObject(test2); os.close(); //And deserialise them java.io.ObjectInputStream is = new java.io.ObjectInputStream(new java.io.FileInputStream("C:\\Users\\Public\\test1.ser")); ContainerClass test3 = (ContainerClass)is.readObject(); is.close(); is = new java.io.ObjectInputStream(new java.io.FileInputStream("C:\\Users\\Public\\test2.ser")); ContainerClass test4 = (ContainerClass)is.readObject(); is.close(); //We expect the same thing as before, and would expect a result of 4321, but this doesn't happen as the referenced objects are now separate instances test3.get().set(4321); System.out.println(Integer.toString(test4.get().get())); } }

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  • Accesing server control from withing app_code class

    - by OverSeven
    My question is about how to acces a server control (listbox) that is located in default.aspx. I wish to acces this control in Functions.cs (this class is located in the App_Code folder). My page structures: - 1 masterpage with 1 content holder - Default.aspx (all the controls are within the content place holder) - Functions.cs (located in App_Code) Now when i try to fill up the listbox elements i get the error "object reference not set to an instance of an object." What i have tried to gain acces to this control: (this code is located in Functions.cs in App_Code). This is basicly showing some items in the listbox that are located in the xml file private static string file = HttpContext.Current.Server.MapPath("~/App_Data/Questions.xml"); public static void ListItems() { XmlDocument XMLDoc = new XmlDocument(); XMLDoc.Load(file); XPathNavigator nav = XMLDoc.CreateNavigator(); XPathExpression expr; expr = nav.Compile("/root/file/naam"); XPathNodeIterator iterator = nav.Select(expr); //ATTEMPT to get acces to ServerControl(listbox) Page page = (Page)HttpContext.Current.Handler; ListBox test = (ListBox)page.FindControl("lbTest"); //control is called lbTest in Default.aspx test.Items.Clear(); while (iterator.MoveNext()) { test.Items.Add(iterator.Current.Value); } } Code from the default.apx file <%@ Page Title="" Language="C#" MasterPageFile="~/MasterFile.master" AutoEventWireup="true" CodeFile="default.aspx.cs" Inherits="default" Debug="true" %> <%@ MasterType TypeName="Master" %> <asp:Content ID="Content1" ContentPlaceHolderID="cphContent" Runat="Server" > <asp:MultiView ID="mvTest" runat="server" > <asp:View ID="vCollection" runat="server"> <asp:ListBox ID="lbTest" runat="server" CssClass="listbox" ></asp:ListBox> </asp:View> </asp:MultiView> </asp:Content> The masterfile itself just has 1 placeholder. Then i call upon the funcion ListItems in the Default.aspx.cs file protected void Page_Load(object sender, EventArgs e) { Functions.ListItems(); } Regards.

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  • Why am I getting ClassNotFoundExpection when I have properly imported said class and am looking at it in its directory?

    - by Strider
    This is my Javac compiling statement: javac -cp "C:\java\code\j3D\j3dcore.jar;C:\java\code\j3D\j3dutils.jar;C:\java\code\j3D\vecmath.jar" Simple.java compiles with no problems. The three jar files (j3dcore, j3dutils, and vecmath) are the essential jar's for my program (or at least I am led to believe according to this official tutorial on J3D For the record I ripped this code almost line from line from this pdf file. jar files are correctly located in referenced locations When I run my Simple program, (java Simple) I am greeted with Exception in thread "main" java.lang.NoClassDefFoundError: javax/media/j3d/Cavas3d Caused by: java.lang.ClassNotFoundExpection: javax.media.j3d.Canvas3D Currently I am staring directly at this Canvas3D.class that is located within j3dcore.jar\javax\media\j3d\ wtfisthis.jpg Here is the source code: //First java3D Program import java.applet.Applet; import java.awt.BorderLayout; import java.awt.Frame; import java.awt.event.*; import com.sun.j3d.utils.applet.MainFrame; import com.sun.j3d.utils.universe.*; import com.sun.j3d.utils.geometry.ColorCube; import javax.media.j3d.*; import javax.vecmath.*; import java.awt.GraphicsConfiguration; public class Simple extends Applet { public Simple() { setLayout(new BorderLayout()); GraphicsConfiguration config = SimpleUniverse.getPreferredConfiguration(); Canvas3D canvas3D = new Canvas3D(config); add("Center", canvas3D); BranchGroup scene = createSceneGraph(); scene.compile(); // SimpleUniverse is a Convenience Utility class SimpleUniverse simpleU = new SimpleUniverse(canvas3D); // This moves the ViewPlatform back a bit so the // objects in the scene can be viewed. simpleU.getViewingPlatform().setNominalViewingTransform(); simpleU.addBranchGraph(scene); } // end of HelloJava3Da (constructor) public BranchGroup createSceneGraph() { // Create the root of the branch graph BranchGroup objRoot = new BranchGroup(); // Create a simple shape leaf node, add it to the scene graph. // ColorCube is a Convenience Utility class objRoot.addChild(new ColorCube(0.4)); return objRoot; } public static void main(String args[]){ Simple world = new Simple(); } }` Did I import correctly? Did I incorrectly reference my jar files in my Javac statement? If I clearly see Canvas3D within its correct directory why cant java find it? The first folder in both j3dcore.jar and vecmath.jar is "javax". Is the compiler getting confused? If the compiler is getting confused how do I specify where to find that exact class when referencing it within my source code?

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  • Communicate progress from local Service

    - by kpdvx
    An application I'm building uses a local Service for downloading files from the web to the phone's SD card. In this app users can browse lists of books, and read them while online. A user can also download a pdf copy of a book for offline viewing. To handle downloads I'm using a locally bound Service. I do not want this Service to run all the time, only when downloading files. So that the Service can shut itself down when its tasks are complete, I am not binding to the service, rather I'm sending an "enqueue for download" command through the Intent passed to Context.startService. Books available for download are shown in a list. A user can choose to download a book by clicking on its row in the list. On download, I need to show download progress using a ProgressBar on the actual book list row. I need to also show, on the rows, if a book is enqueued for download, or if its download has completed or failed. The books can be shown in different activities throughout the application--in search, or in the user's list of favorite books, for example. When the books are shown in different places, these are not the same objects, but they are uniquely identified by their bookId. Because I do not want to bind to the service from every Activity, my tentative plan was to use a public static final HashMap on the Service class itself to contain a mapping of bookId to download status, an enum of enqueued, downloading, cancelled, etc. Each book view, when displayed, would check this static HashMap, and if the bookId is in the map, retrieve and display its status. I don't particularly like this idea, but at the moment it's the only way I can think of to retrieve status from the Service without having to bind to it and start it. Additionally I need to retrieve download progress percent from the Service, for a given bookId, if it is the active download. Again I'd rather not bind to the service from every activity, so I'm not sure how to go about retrieving current progress from the Service. My current plan is to use some sort of singleton mediator, that the Service will push updates to, and the views can read from. But I'm not terribly happy with this idea. The reason I'd like to avoid binding to the Service from each Activity is 1.) I'm already running another Service and 2.) binding is verbose and I'd like to avoid needing to pass around a reference to the Service (but admittedly this isn't too much of a problem). Perhaps binding to the local Service isn't expensive enough to warrant this other setup? Should I not be concerned about binding to it from each Activity? Maybe this is a non-issue?

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  • NSString cannot be released

    - by Stanley
    Consider the following method and the caller code block. The method analyses a NSString and extracts a "http://" string which it passes out by reference as an auto release object. Without releasing g_scan_result, the program works as expected. But according to non-arc rules, g_scan_result should be released since a retain has been called against it. My question are : Why g_scan_result cannot be released ? Is there anything wrong the way g_scan_result is handled in the posted coding below ? Is it safe not to release g_scan_result as long as the program runs correctly and the XCode Memory Leak tool does not show leakage ? Which XCode profile tools should I look into to check and under which subtitle ? Hope somebody knowledgeable could help. - (long) analyse_scan_result :(NSString *)scan_result target_url :(NSString **)targ_url { NSLog (@" RES analyse string : %@", scan_result); NSRange range = [scan_result rangeOfString:@"http://" options:NSCaseInsensitiveSearch]; if (range.location == NSNotFound) { *targ_url = @""; NSLog(@"fnd string not found"); return 0; } NSString *sub_string = [scan_result substringFromIndex : range.location]; range = [sub_string rangeOfString : @" "]; if (range.location != NSNotFound) { sub_string = [sub_string substringToIndex : range.location]; } NSLog(@" FND sub_string = %@", sub_string); *targ_url = sub_string; return [*targ_url length]; } The following is the caller code block, also note that g_scan_result has been declared and initialized (on another source file) as : NSString *g_scan_result = nil; Please do send a comment or answer if you have suggestions or find possible errors in code posted here (or above). Xcode memory tools does not seem to show any memory leak. But it may be because I do not know where to look as am new to the memory tools. { long url_leng = [self analyse_scan_result:result target_url:&targ_url]; NSLog(@" TAR target_url = %@", targ_url); UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Scanned Result" message:result delegate:g_alert_view_delegate cancelButtonTitle:@"OK" otherButtonTitles:nil]; if (url_leng) { // ****** The 3 commented off statements // ****** cannot be added without causing // ****** a crash after a few scan result // ****** cycles. // ****** NSString *t_url; if (g_system_status.language_code == 0) [alert addButtonWithTitle : @"Open"]; else if (g_system_status.language_code == 1) [alert addButtonWithTitle : @"Abrir"]; else [alert addButtonWithTitle : @"Open"]; // ****** t_url = g_scan_result; g_scan_result = [targ_url retain]; // ****** [t_url release]; } targ_url = nil; [alert show]; [alert release]; [NSTimer scheduledTimerWithTimeInterval:5.0 target:self selector:@selector(activate_qr_scanner:) userInfo:nil repeats:NO ]; return; }

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  • Double Linked List header node keeps returning first value as 0

    - by Craig
    I will preface to say that this is my first question. I am currently getting my Masters degree in Information Security and I had to take C++ programming this semester. So this is homework related. I am not looking for you to answer my homework but I am running into a peculiar situation. I have created the program to work with a doubly linked list and everything works fine. However when I have the user create a list of values the first node keeps returning 0. I have tried finding some reading on this and I cannot locate any reference to it. My question is then is the header node(first node) always going to be zero? Or am I doing something wrong. case: 'C': cout<<"Please enter a list:"<<endl; while(n!=-999){ myList.insert(n); cin>> n;} break; I now enter: 12321, 1234,64564,346346. The results in 0, 12321, 1234, 64564,346346. Is this what should happen or am I doing something wrong? Also as this is my first post please feel free to criticize or teach me how to color code the keywords. Anyway this is a homework assignment so I am only looking for guidance and constructive criticism. Thank you all in advance So I cannot figure out the comment sections on this forum so I will edit the original post The first section is the constructor code: template <class Type> doublyLinkedList<Type>::doublyLinkedList() { first= NULL; last = NULL; count = 0; } Then there is my insert function : template <class Type> void doublyLinkedList<Type>::insert(const Type& insertItem) { nodeType<Type> *current; //pointer to traverse the list nodeType<Type> *trailCurrent; //pointer just before current nodeType<Type> *newNode; //pointer to create a node bool found; newNode = new nodeType<Type>; //create the node newNode->info = insertItem; //store the new item in the node newNode->next = NULL; newNode->back = NULL; if(first == NULL) //if the list is empty, newNode is //the only node { first = newNode; last = newNode; count++; } else { found = false; current = first; while (current != NULL && !found) //search the list if (current->info >= insertItem) found = true; else { trailCurrent = current; current = current->next; } if (current == first) //insert newNode before first { first->back = newNode; newNode->next = first; first = newNode; count++; } else { //insert newNode between trailCurrent and current if (current != NULL) { trailCurrent->next = newNode; newNode->back = trailCurrent; newNode->next = current; current->back = newNode; } else { trailCurrent->next = newNode; newNode->back = trailCurrent; last = newNode; } count++; }//end else }//end else }//end Then I have an initialization function too: template <class Type> void doublyLinkedList<Type>::initializeList() { destroy(); } Did I miss anything?

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  • can't able to integrate base64decode in my class

    - by MaheshBabu
    Hi folks, i am getting the image that is in base64 encoded format. I need to decode it. i am writing the code for decoding is + (NSData *) base64DataFromString: (NSString *)string { unsigned long ixtext, lentext; unsigned char ch, input[4], output[3]; short i, ixinput; Boolean flignore, flendtext = false; const char *temporary; NSMutableData *result; if (!string) return [NSData data]; ixtext = 0; temporary = [string UTF8String]; lentext = [string length]; result = [NSMutableData dataWithCapacity: lentext]; ixinput = 0; while (true) { if (ixtext >= lentext) break; ch = temporary[ixtext++]; flignore = false; if ((ch >= 'A') && (ch <= 'Z')) ch = ch - 'A'; else if ((ch >= 'a') && (ch <= 'z')) ch = ch - 'a' + 26; else if ((ch >= '0') && (ch <= '9')) ch = ch - '0' + 52; else if (ch == '+') ch = 62; else if (ch == '=') flendtext = true; else if (ch == '/') ch = 63; else flignore = true; if (!flignore) { short ctcharsinput = 3; Boolean flbreak = false; if (flendtext) { if (ixinput == 0) break; if ((ixinput == 1) || (ixinput == 2)) { ctcharsinput = 1; else ctcharsinput = 2; ixinput = 3; flbreak = true; } input[ixinput++] = ch; if (ixinput == 4) ixinput = 0; output[0] = (input[0] << 2) | ((input[1] & 0x30) >> 4); output[1] = ((input[1] & 0x0F) << 4) | ((input[2] & 0x3C) >> 2); output[2] = ((input[2] & 0x03) << 6) | (input[3] & 0x3F); for (i = 0; i < ctcharsinput; i++) [result appendBytes: &output[i] length: 1]; } if (flbreak) break; } return result; } i am calling this in my method like this NSData *data = [base64DataFromString:theXML]; theXML is encoded data. but it shows error decodeBase64 undeclared. How can i use this method. can any one pls help me. Thank u in advance.

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  • Edges on polygon outlines not always correct

    - by user146780
    I'm using the algorithm below to generate quads which are then rendered to make an outline like this http://img810.imageshack.us/img810/8530/uhohz.png The problem as seen on the image, is that sometimes the lines are too thin when they should always be the same width. My algorithm finds the 4 verticies for the first one then the top 2 verticies of the next ones are the bottom 2 of the previous. This creates connected lines, but it seems to not always work. How could I fix this? This is my algorithm: void OGLENGINEFUNCTIONS::GenerateLinePoly(const std::vector<std::vector<GLdouble>> &input, std::vector<GLfloat> &output, int width) { output.clear(); if(input.size() < 2) { return; } int temp; float dirlen; float perplen; POINTFLOAT start; POINTFLOAT end; POINTFLOAT dir; POINTFLOAT ndir; POINTFLOAT perp; POINTFLOAT nperp; POINTFLOAT perpoffset; POINTFLOAT diroffset; POINTFLOAT p0, p1, p2, p3; for(unsigned int i = 0; i < input.size() - 1; ++i) { start.x = static_cast<float>(input[i][0]); start.y = static_cast<float>(input[i][1]); end.x = static_cast<float>(input[i + 1][0]); end.y = static_cast<float>(input[i + 1][1]); dir.x = end.x - start.x; dir.y = end.y - start.y; dirlen = sqrt((dir.x * dir.x) + (dir.y * dir.y)); ndir.x = static_cast<float>(dir.x * 1.0 / dirlen); ndir.y = static_cast<float>(dir.y * 1.0 / dirlen); perp.x = dir.y; perp.y = -dir.x; perplen = sqrt((perp.x * perp.x) + (perp.y * perp.y)); nperp.x = static_cast<float>(perp.x * 1.0 / perplen); nperp.y = static_cast<float>(perp.y * 1.0 / perplen); perpoffset.x = static_cast<float>(nperp.x * width * 0.5); perpoffset.y = static_cast<float>(nperp.y * width * 0.5); diroffset.x = static_cast<float>(ndir.x * 0 * 0.5); diroffset.y = static_cast<float>(ndir.y * 0 * 0.5); // p0 = start + perpoffset - diroffset //p1 = start - perpoffset - diroffset //p2 = end + perpoffset + diroffset // p3 = end - perpoffset + diroffset p0.x = start.x + perpoffset.x - diroffset.x; p0.y = start.y + perpoffset.y - diroffset.y; p1.x = start.x - perpoffset.x - diroffset.x; p1.y = start.y - perpoffset.y - diroffset.y; if(i > 0) { temp = (8 * (i - 1)); p2.x = output[temp + 2]; p2.y = output[temp + 3]; p3.x = output[temp + 4]; p3.y = output[temp + 5]; } else { p2.x = end.x + perpoffset.x + diroffset.x; p2.y = end.y + perpoffset.y + diroffset.y; p3.x = end.x - perpoffset.x + diroffset.x; p3.y = end.y - perpoffset.y + diroffset.y; } output.push_back(p2.x); output.push_back(p2.y); output.push_back(p0.x); output.push_back(p0.y); output.push_back(p1.x); output.push_back(p1.y); output.push_back(p3.x); output.push_back(p3.y); } } Thanks

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  • Making a Wrapper class for ActiveMQ

    - by DarthVader
    I want to make a Wrapper class for ActiveMQ which will have only send and get functions. I want to wrap them in a static class. Users can use this client and send, get messages to the activemq instance. I want this process to be transparent. There are two classes in this link My only handicap is, i need to this in c++ and not sure where to start. I havent used c++ for ages and now not sure how I can create this wrapper class. I m giving it a try as follows: // .h file #include <stdlib.h> #include <iostream> using namespace std; class ActiveMQWrapper { public: static void send(std::string message); static std::string get(); }; // .cpp file #include<string> #include<iostream> #include "ActiveMQWrapper.h" void ActiveMQWrapper::send(std::string message){ std::cout<<message; } std::string ActiveMQWrapper::get(){ return "test"; } // test file #include <string> #include <iostream> #include "ActiveMQWrapper.h" int main() { std::string foo ="test"; ActiveMQWrapper::send(foo); std::cout<<ActiveMQWrapper::get(); return 1; } When I added the following to .h file, hell breaks loose. Do you think I should seperate this impl to a factory and initialize and instance and return to the wrapper above? How do i deal with all the dependencies? private: Connection* connection; Session* session; Destination* destination; MessageProducer* producer; int numMessages; bool useTopic; bool sessionTransacted; std::string brokerURI; and the header files, i get several messages as errors, which complains about the path. How can i get this correct? I eventually want to build a Factory, get an instance and send or get the messages to the queue. is there a code sample i can look into to get this right? essential i want to use the functionality of only this producer and consumer. Edit: I understand there is no such thing as static class in C++ . This is my reference.

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  • Translating a C# WCF app into Visual Basic

    - by MikeG
    I'm trying to write a simple/small Windows Communication Foundation service application in Visual Basic (but I am very novice in VB) and all the good examples I've found on the net are written in C#. So far I've gotten my WCF service application working but now I'm trying to add callback functionality and the program has gotten more complicated. In the C# example code I understand how everything works but I am having trouble translating into VB the portion of code that uses a delegate. Can someone please show the VB equivalent? Here is the C# code sample I'm using for reference: namespace WCFCallbacks { using System; using System.ServiceModel; [ServiceContract(CallbackContract = typeof(IMessageCallback))] public interface IMessage { [OperationContract] void AddMessage(string message); [OperationContract] bool Subscribe(); [OperationContract] bool Unsubscribe(); } interface IMessageCallback { [OperationContract(IsOneWay = true)] void OnMessageAdded(string message, DateTime timestamp); } } namespace WCFCallbacks { using System; using System.Collections.Generic; using System.ServiceModel; public class MessageService : IMessage { private static readonly List<IMessageCallback> subscribers = new List<IMessageCallback>(); //The code in this AddMessage method is what I'd like to see re-written in VB... public void AddMessage(string message) { subscribers.ForEach(delegate(IMessageCallback callback) { if (((ICommunicationObject)callback).State == CommunicationState.Opened) { callback.OnMessageAdded(message, DateTime.Now); } else { subscribers.Remove(callback); } }); } public bool Subscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); if (!subscribers.Contains(callback)) subscribers.Add(callback); return true; } catch { return false; } } public bool Unsubscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); if (!subscribers.Contains(callback)) subscribers.Remove(callback); return true; } catch { return false; } } } } I was thinking I could do something like this but I don't know how to pass the message string from AddMessage to DoSomething... Dim subscribers As New List(Of IMessageCallback) Public Sub AddMessage(ByVal message As String) Implements IMessage.AddMessage Dim action As Action(Of IMessageCallback) action = AddressOf DoSomething subscribers.ForEach(action) 'Or this instead of the above three lines: 'subscribers.ForEach(AddressOf DoSomething) End Sub Public Sub DoSomething(ByVal callback As IMessageCallback) 'I am also confused by: '((ICommunicationObject)callback).State 'Is that casting the callback object as type ICommunicationObject? 'How is that done in VB? End Sub

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  • Several C# Language Questions

    - by Water Cooler v2
    1) What is int? Is it any different from the struct System.Int32? I understand that the former is a C# alias (typedef or #define equivalant) for the CLR type System.Int32. Is this understanding correct? 2) When we say: IComparable x = 10; Is that like saying: IComparable x = new System.Int32(); But we can't new a struct, right? or in C like syntax: struct System.In32 *x; x=>someThing = 10; 3) What is String with a capitalized S? I see in Reflector that it is the sealed String class, which, of course, is a reference type, unlike the System.Int32 above, which is a value type. What is string, with an uncapitalized s, though? Is that also the C# alias for this class? Why can I not see the alias definitions in Reflector? 4) Try to follow me down this subtle train of thought, if you please. We know that a storage location of a particular type can only access properties and members on its interface. That means: Person p = new Customer(); p.Name = "Water Cooler v2"; // legal because as Name is defined on Person. but // illegal without an explicit cast even though the backing // store is a Customer, the storage location is of type // Person, which doesn't support the member/method being // accessed/called. p.GetTotalValueOfOrdersMade(); Now, with that inference, consider this scenario: int i = 10; // obvious System.object defines no member to // store an integer value or any other value in. // So, my question really is, when the integer is // boxed, what is the *type* it is actually boxed to. // In other words, what is the type that forms the // backing store on the heap, for this operation? object x = i; Update Thank you for your answers, Eric Gunnerson and Aaronought. I'm afraid I haven't been able to articulate my questions well enough to attract very satisfying answers. The trouble is, I do know the answers to my questions on the surface, and I am, by no means, a newbie programmer. But I have to admit, a deeper understanding to the intricacies of how a language and its underlying platform/runtime handle storage of types has eluded me for as long as I've been a programmer, even though I write correct code.

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  • factory class, wrong number of arguments being passed to subclass constructor

    - by Hugh Bothwell
    I was looking at Python: Exception in the separated module works wrong which uses a multi-purpose GnuLibError class to 'stand in' for a variety of different errors. Each sub-error has its own ID number and error format string. I figured it would be better written as a hierarchy of Exception classes, and set out to do so: class GNULibError(Exception): sub_exceptions = 0 # patched with dict of subclasses once subclasses are created err_num = 0 err_format = None def __new__(cls, *args): print("new {}".format(cls)) # DEBUG if len(args) and args[0] in GNULibError.sub_exceptions: print(" factory -> {} {}".format(GNULibError.sub_exceptions[args[0]], args[1:])) # DEBUG return super(GNULibError, cls).__new__(GNULibError.sub_exceptions[args[0]], *(args[1:])) else: print(" plain {} {}".format(cls, args)) # DEBUG return super(GNULibError, cls).__new__(cls, *args) def __init__(self, *args): cls = type(self) print("init {} {}".format(cls, args)) # DEBUG self.args = args if cls.err_format is None: self.message = str(args) else: self.message = "[GNU Error {}] ".format(cls.err_num) + cls.err_format.format(*args) def __str__(self): return self.message def __repr__(self): return '{}{}'.format(type(self).__name__, self.args) class GNULibError_Directory(GNULibError): err_num = 1 err_format = "destination directory does not exist: {}" class GNULibError_Config(GNULibError): err_num = 2 err_format = "configure file does not exist: {}" class GNULibError_Module(GNULibError): err_num = 3 err_format = "selected module does not exist: {}" class GNULibError_Cache(GNULibError): err_num = 4 err_format = "{} is expected to contain gl_M4_BASE({})" class GNULibError_Sourcebase(GNULibError): err_num = 5 err_format = "missing sourcebase argument: {}" class GNULibError_Docbase(GNULibError): err_num = 6 err_format = "missing docbase argument: {}" class GNULibError_Testbase(GNULibError): err_num = 7 err_format = "missing testsbase argument: {}" class GNULibError_Libname(GNULibError): err_num = 8 err_format = "missing libname argument: {}" # patch master class with subclass reference # (TO DO: auto-detect all available subclasses instead of hardcoding them) GNULibError.sub_exceptions = { 1: GNULibError_Directory, 2: GNULibError_Config, 3: GNULibError_Module, 4: GNULibError_Cache, 5: GNULibError_Sourcebase, 6: GNULibError_Docbase, 7: GNULibError_Testbase, 8: GNULibError_Libname } This starts out with GNULibError as a factory class - if you call it with an error number belonging to a recognized subclass, it returns an object belonging to that subclass, otherwise it returns itself as a default error type. Based on this code, the following should be exactly equivalent (but aren't): e = GNULibError(3, 'missing.lib') f = GNULibError_Module('missing.lib') print e # -> '[GNU Error 3] selected module does not exist: 3' print f # -> '[GNU Error 3] selected module does not exist: missing.lib' I added some strategic print statements, and the error seems to be in GNULibError.__new__: >>> e = GNULibError(3, 'missing.lib') new <class '__main__.GNULibError'> factory -> <class '__main__.GNULibError_Module'> ('missing.lib',) # good... init <class '__main__.GNULibError_Module'> (3, 'missing.lib') # NO! ^ why? I call the subclass constructor as subclass.__new__(*args[1:]) - this should drop the 3, the subclass type ID - and yet its __init__ is still getting the 3 anyway! How can I trim the argument list that gets passed to subclass.__init__?

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  • C problem, left of '->' must point to class/struct/union/generic type ??

    - by Patrick
    Hello! Trying to understand why this doesn't work. I keep getting the following errors: left of '-nextNode' must point to class/struct/union/generic type (Also all the lines with a - in the function new_math_struct) Header file #ifndef MSTRUCT_H #define MSTRUCT_H #define PLUS 0 #define MINUS 1 #define DIVIDE 2 #define MULTIPLY 3 #define NUMBER 4 typedef struct math_struct { int type_of_value; int value; int sum; int is_used; struct math_struct* nextNode; } ; typedef struct math_struct* math_struct_ptr; #endif C file int get_input(math_struct_ptr* startNode) { /* character, input by the user */ char input_ch; char* input_ptr; math_struct_ptr* ptr; math_struct_ptr* previousNode; input_ptr = &input_ch; previousNode = startNode; /* as long as input is not ok */ while (1) { input_ch = get_input_character(); if (input_ch == ',') // Carrage return return 1; else if (input_ch == '.') // Illegal character return 0; if (input_ch == '+') ptr = new_math_struct(PLUS, 0); else if (input_ch == '-') ptr = new_math_struct(MINUS, 0); else if (input_ch == '/') ptr = new_math_struct(DIVIDE, 0); else if (input_ch == '*') ptr = new_math_struct(MULTIPLY, 0); else ptr = new_math_struct(NUMBER, atoi(input_ptr)); if (startNode == NULL) { startNode = previousNode = ptr; } else { previousNode->nextNode = ptr; previousNode = ptr; } } return 0; } math_struct_ptr* new_math_struct(int symbol, int value) { math_struct_ptr* ptr; ptr = (math_struct_ptr*)malloc(sizeof(math_struct_ptr)); ptr->type_of_value = symbol; ptr->value = value; ptr->sum = 0; ptr->is_used = 0; return ptr; } char get_input_character() { /* character, input by the user */ char input_ch; /* get the character */ scanf("%c", &input_ch); if (input_ch == '+' || input_ch == '-' || input_ch == '*' || input_ch == '/' || input_ch == ')') return input_ch; // A special character else if (input_ch == '\n') return ','; // A carrage return else if (input_ch < '0' || input_ch > '9') return '.'; // Not a number else return input_ch; // Number } The header for the C file just contains a reference to the struct header and the definitions of the functions. Language C.

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  • c++ template function compiles in header but not implementation

    - by flies
    I'm trying to learn templates and I've run into this confounding error. I'm declaring some functions in a header file and I want to make a separate implementation file where the functions will be defined. Here's the code that calls the header (dum.cpp): #include <iostream> #include <vector> #include <string> #include "dumper2.h" int main() { std::vector<int> v; for (int i=0; i<10; i++) { v.push_back(i); } test(); std::string s = ", "; dumpVector(v,s); } now, here's a working header file (dumper2.h): #include <iostream> #include <string> #include <vector> void test(); template <class T> void dumpVector( std::vector<T> v,std::string sep); template <class T> void dumpVector(std::vector<T> v, std::string sep) { typename std::vector<T>::iterator vi; vi = v.begin(); std::cout << *vi; vi++; for (;vi<v.end();vi++) { std::cout << sep << *vi ; } std::cout << "\n"; return; } with implentation (dumper2.cpp): #include <iostream> #include "dumper2.h" void test() { std::cout << "!olleh dlrow\n"; } the weird thing is that if I move the code that defines dumpVector from the .h to the .cpp file, I get the following error: g++ -c dumper2.cpp -Wall -Wno-deprecated g++ dum.cpp -o dum dumper2.o -Wall -Wno-deprecated /tmp/ccKD2e3G.o: In function `main': dum.cpp:(.text+0xce): undefined reference to `void dumpVector<int>(std::vector<int, std::allocator<int> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >)' collect2: ld returned 1 exit status make: *** [dum] Error 1 So why does it work one way and not the other? Clearly the compiler can find test(), so why can't it find dumpVector?

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  • Is this the correct way to build a Perl hash that utilizes arrays?

    - by Structure
    This is the first time I have manipulated hashes and arrays in this way -- and it is working. Basically, for every key there are multiple values that I want to record and then print out in the form "key -- value -- value -- val..." My code is as follows. I am surprised that it works, so concerned that it works "by mistake". Is this the correct way to accomplish this task, or is there a more efficient or appropriate method? while ($source =~ m/(regex)/g) { #Get all key names from source $listkey = $1; #Set current list key to the current regex result. $list{$listkey} = ++$i unless $list{$listkey}; #Add the key to the hash unless it already exists. $list{$listkey} = [] unless exists $list{$listkey}; #Add an array for the hash unless the hash already exists. while ($loopcount==0) { if ($ifcount==0) { $listvalue=result_of_some_function_using_list_key; #Get the first list value from the list key. $ifcount++; #Increment so we only get the first list value once. } else { $listvalue=result_of_some_function_using_list_value; #Update the last list value. } if ($listvalue) { #If the function returned a value... push @{$list{$listkey}}, $listvalue; #...then add the value to the hash array for the key. } else { #There are no more values and we need a new key. $listkey=0; #Reset variable. $domain=0; #Reset variable. $loopcount++; #Increment loop counter to exit loop. } } $ifcount=0; #Reset count variable so the next listvalue can be generated from the new key. $loopcount=0; #Reset count variable so another loop can begin for a new key. } foreach $listkey (keys %list) { #For each key in the hash. print "$listkey --> "; #Print the key. @values = @{$list{$listkey}}; #Reference the arrays of the hash. print join ' --> ', @values; #Print the values. print "\n"; #Print new line. }

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  • Templates, interfaces (multiple inheritance) and static functions (named constructors)

    - by fledgling Cxx user
    Setup I have a graph library where I am trying to decompose things as much as possible, and the cleanest way to describe it that I found is the following: there is a vanilla type node implementing only a list of edges: class node { public: int* edges; int edge_count; }; Then, I would like to be able to add interfaces to this whole mix, like so: template <class T> class node_weight { public: T weight; }; template <class T> class node_position { public: T x; T y; }; and so on. Then, the actual graph class comes in, which is templated on the actual type of node: template <class node_T> class graph { protected: node_T* nodes; public: static graph cartesian(int n, int m) { graph r; r.nodes = new node_T[n * m]; return r; } }; The twist is that it has named constructors which construct some special graphs, like a Cartesian lattice. In this case, I would like to be able to add some extra information into the graph, depending on what interfaces are implemented by node_T. What would be the best way to accomplish this? Possible solution I thought of the following humble solution, through dynamic_cast<>: template <class node_T, class weight_T, class position_T> class graph { protected: node_T* nodes; public: static graph cartesian(int n, int m) { graph r; r.nodes = new node_T[n * m]; if (dynamic_cast<node_weight<weight_T>>(r.nodes[0]) != nullptr) { // do stuff knowing you can add weights } if (dynamic_cast<node_position<positionT>>(r.nodes[0]) != nullptr) { // do stuff knowing you can set position } return r; } }; which would operate on node_T being the following: template <class weight_T, class position_T> class node_weight_position : public node, public node_weight<weight_T>, public node_position<position_T> { // ... }; Questions Is this -- philosophically -- the right way to go? I know people don't look nicely at multiple inheritance, though with "interfaces" like these it should all be fine. There are unfortunately problems with this. From what I know at least, dynamic_cast<> involves quite a bit of run-time overhead. Hence, I run into a problem with what I had solved earlier: writing graph algorithms that require weights independently of whether the actual node_T class has weights or not. The solution with this 'interface' approach would be to write a function: template <class node_T, class weight_T> inline weight_T get_weight(node_T const & n) { if (dynamic_cast<node_weight<weight_T>>(n) != nullptr) { return dynamic_cast<node_weight<weight_T>>(n).weight; } return T(1); } but the issue with it is that it works using run-time information (dynamic_cast), yet in principle I would like to decide it at compile-time and thus make the code more efficient. If there is a different solution that would solve both problems, especially a cleaner and better one than what I have, I would love to hear about it!

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  • Mobile Safari text selection after input field focus

    - by Andy
    I have some legacy html that needs to work on old and new browsers (down to IE7) as well as the iPad. The iPad is the biggest issues because of how text selection is handled. On a page there is a textarea as well as some text instructions. The instructions are in a <div> and the user needs to be able to select the instructions. The problem is that once focus is placed in the textarea, the user cannot subsequently select the text instructions in the <div>. This is because the text cannot receive focus. According to the Safari Web Content Guide: Handling Events (especially, "Making Elements Clickable"), you can add a onclick event handler to the div you want to receive focus. This solution works (although it is not ideal) in iOS 6x but it does not work in iOS 5x. Does anyone have a suggestion that minimizes changes to our existing code and produces consistant user interaction. Here is sample code that shows the problem. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <script src="http://code.jquery.com/jquery-1.8.2.js"></script> <!-- Resources: Safari Web Content Guide: Handling Events (especially, "Making Elements Clickable") http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/HandlingEvents/HandlingEvents.html#//apple_ref/doc/uid/TP40006511-SW1 --> </head> <body> <div style="width:550"> <div onclick='function() { void(0); }'> <p>On the iPad, I want to be able to select this text after the textarea has had focus.</p> </div> <textarea rows="20" cols="80">After focus is in the textarea, can you select the text above?</textarea> </div> </body> </html>

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