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  • explain notifier.c from the Linux kernel

    - by apollon
    I'm seeking to fully understand the following code snippet from kernel/notifier.c. I have read and built simple link lists and think I get the construct from K&R's C programming. The second line below which begins with the 'int' appears to be two items together which is unclear. The first is the (*notifier_call) which I believe has independent but related significance with the second containing a 'notifier block' term. Can you explain how it works in detail? I understand that there is a function pointer and multiple subscribers possible. But I lack the way to tie these facts together, and could use a primer or key so I exactly understand how the code works. The third line looks to contain the linking structure, or recursive nature. Forgive my terms, and correct them as fit as I am a new student of computer science terminology. struct notifier_block { int (*notifier_call)(struct notifier_block *, unsigned long, void *); struct notifier_block *next; int priority; };

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  • Pointer inside a struct / thread

    - by bruno
    Hi! I have this warning "warning: assignment from incompatible pointer type " in this line: data1->transformed_block[l] = &transformed_block[l]; - void print_message_function ( void *ptr ) { dt *data; data = (dt *) ptr; printf("Dentro da thread Numero0: %ld\n", data->L_norm_NewBlock); pthread_exit(0); } typedef struct data_thread { long L_norm_NewBlock; int Bsize_X; int Bsize_Y; int *transformed_block[MAX_LEVEL]; long L_norm_OrigBlock; } dt; void function() { int *transformed_block[MAX_LEVEL]; pthread_t thread1; dt *data1; pthread_attr_t attr; pthread_attr_init(&attr); //Fills structure data1 = (dt *) malloc(sizeof(dt)); data1->transformed_block[l] = &transformed_block[l]; data1->L_norm_NewBlock=0; data1->Bsize_Y = Bsize_Y; data1->Bsize_X = Bsize_X; pthread_create(&thread1, &attr, (void *) &print_message_function, (void *) &data1); } I want to get rid of that warning, and the values i get inside the thread are wrong. For example data1-L_norm_NewBlock=0; in the thread guives me a differente value (not 0 like it should be).

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  • MVC design pattern in complex iPad app: is one fat controller acceptable?

    - by nutsmuggler
    I am building a complex iPad application; think of it as a scrapbook. For the purpose of this question, let's consider a page with two images over it. My main view displays my doc data rendered as a single UIImage; this because I need to do some global manipulation over them. This is my DisplayView. When editing I need to instantiate an EditorView with my two images as subviews; this way I can interact with a single image, (rotate it, scale it, move it). When editing is triggered, I hide my DisplayView and show my EditorView. In a iPhone app, I'd associate each main view (that is, a view filling the screen) to a view controller. The problem is here there is just one view controller; I've considered passing the EditorView via a modal view controller, but it's not an option (there a complex layout with a mask covering everything and palettes over it; rebuilding it in the EditorView would create duplicate code). Presently the EditorView incorporates some logic (loads data from the model, invokes some subviews for fine editing, saves data back to the model); EditorView subviews also incorporate some logic (I manipulate images and pass them back to the main EditorView). I feel this logic belongs more to a controller. On the other hand, I am not sure making my only view controller so fat a good idea. What is the best, cocoa-ish implementation of such a class structure? Feel free to ask for clarifications. Cheers.

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  • Deleting unneeded rows from a table with 2 criteria

    - by stormbreaker
    Hello. I have a many-to-many relations table and I need to DELETE the unneeded rows. The lastviews table's structure is: | user (int) | document (int) | time (datetime) | This table logs the last users which viewed the document. (user, document) is unique. I show only the last 10 views of a document and until now I deleted the unneeded like this: DELETE FROM `lastviews` WHERE `document` = ? AND `user` NOT IN (SELECT * FROM (SELECT `user` FROM `lastviews` WHERE `document` = ? ORDER BY `time` DESC LIMIT 10) AS TAB) However, now I need to also show the last 5 documents a user has viewed. This means I can no longer delete rows using the previous query because it might delete information I need (say a user didn't view documents in 5 minutes and the rows are deleted) To sum up, I need to delete all the records that don't fit these 2 criterias: SELECT ... FROM `lastviews` WHERE `document` = ? ORDER BY `time` DESC LIMIT 10 and SELECT * FROM `lastviews` WHERE `user` = ? ORDER BY `time` DESC LIMIT 0, 5 I need the logic. Thanks in advance.

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  • Access array of c-structs using Python ctypes

    - by sadris
    I have a C-function that allocates memory at the address passed to and is accessed via Python. The pointer contents does contain an array of structs in the C code, but I am unable to get ctypes to access the array properly beyond the 0th element. How can I get the proper memory offset to be able to access the non-zero elements? Python's ctypes.memset is complaining about TypeErrors if I try to use their ctypes.memset function. typedef struct td_Group { unsigned int group_id; char groupname[256]; char date_created[32]; char date_modified[32]; unsigned int user_modified; unsigned int user_created; } Group; int getGroups(LIBmanager * handler, Group ** unallocatedPointer); ############# python code below: class Group(Structure): _fields_ = [("group_id", c_uint), ("groupname", c_char*256), ("date_created", c_char*32), ("date_modified", c_char*32), ("user_modified", c_uint), ("user_created", c_uint)] myGroups = c_void_p() count = libnativetest.getGroups( nativePointer, byref(myGroups) ) casted = cast( myGroups, POINTER(Group*count) ) for x in range(0,count): theGroup = cast( casted[x], POINTER(Group) ) # this only works for the first entry in the array: print "~~~~~~~~~~" + theGroup.contents.groupname Related: Access c_char_p_Array_256 in Python using ctypes

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  • For each result in MySQL query, push to array (complicated)

    - by Dylan Taylor
    Okay, here's what I'm trying to do. I am running a MySQL query for the most recent posts. For each of the returned rows, I need to push the ID of the row to an array, then within that ID in the array, I need to add more data from the rows. A multi-dimensional array. Here's my code thus far. $query = "SELECT * FROM posts ORDER BY id DESC LIMIT 10"; $result = mysql_query($query); while($row = mysql_fetch_array($result)){ $id = $row["id"]; $post_title = $row["title"]; $post_text = $row["text"]; $post_tags = $row["tags"]; $post_category = $row["category"]; $post_date = $row["date"]; } As you can see I haven't done anything with arrays yet. Here's an ideal structure I'm looking for, just incase you're confused. The master array I guess you could call it. We'll just call this array $posts. Within this array, I have one array for each row returned in my MySQL query. Within those arrays there is the $post_title, $post_text, etc. How do I do this? I'm so confused.. an example would be really appreciated. -Dylan

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  • Getting memory leak at NSURL connection in Iphone sdk.

    - by monish
    Hi guys, Here Im getting leak at the NSURL connection in my libxml parser can anyone tell how to resolve it. The code where leak generates is: - (BOOL)parseWithLibXML2Parser { BOOL success = NO; ZohoAppDelegate *appDelegate = (ZohoAppDelegate*) [ [UIApplication sharedApplication] delegate]; NSString* curl; if ([cName length] == 0) { curl = @"https://invoice.zoho.com/api/view/settings/currencies?ticket="; curl = [curl stringByAppendingString:appDelegate.ticket]; curl = [curl stringByAppendingString:@"&apikey="]; curl = [curl stringByAppendingString:appDelegate.apiKey]; curl = [curl stringByReplacingOccurrencesOfString:@"\n" withString:@""]; } NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:curl]]; NSLog(@"the request parserWithLibXml2Parser %@",theRequest); NSURLConnection *con = [[[NSURLConnection alloc] initWithRequest:theRequest delegate:self] autorelease];//Memory leak generated here at this line of code. //self.connection = con; //[con release]; // This creates a context for "push" parsing in which chunks of data that are // not "well balanced" can be passed to the context for streaming parsing. // The handler structure defined above will be used for all the parsing. The // second argument, self, will be passed as user data to each of the SAX // handlers. The last three arguments are left blank to avoid creating a tree // in memory. _xmlParserContext = xmlCreatePushParserCtxt(&simpleSAXHandlerStruct, self, NULL, 0, NULL); if(con != nil) { do { [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]; } while (!_done && !self.error); } if(self.error) { //NSLog(@"parsing error"); [self.delegate parser:self encounteredError:nil]; } else { success = YES; } return success; } Anyone's help will be muck appreciated . Thank you, Monish.

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  • Entities used to serialize data have changed. How can the serialized data be upgraded for the new entities?

    - by i8abug
    Hi, I have a bunch of simple entity instances that I have serialized to a file. In the future, I know that the structure of these entities (ie, maybe I will rename Name to Header or something). The thing is, I don't want to lose the data that I have saved in all these old files. What is the proper way to either load the data from the old entities into new entities upgrade the old files so that they can be used with new entities Note: I think I am stuck with binary serialization, not xml serialization. Thanks in advance! Edit: So I have an answer for the case I have described. I can use a dataContractSerializer and do something like [DataMember("bar")] private string foo; and change the name in the code and keep the same name that was used for serialization. But what about the following additional cases: The original entity has new members which can be serialized Some serialized members that were in the original entity are removed Some members have actually changed in function (suppose that the original class had a FirstName and LastName member and it has been refactored to have only a FullName member which combines the two) To handle these, I need some sort of interpreter/translator deserialization class but I have no idea what I should use

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  • Best solution for __autoload

    - by tpk
    As our PHP5 OO application grew (in both size and traffic), we decided to revisit the __autoload() strategy. We always name the file by the class definition it contains, so class Customer would be contained within Customer.php. We used to list the directories in which a file can potentially exist, until the right .php file was found. This is quite inefficient, because you're potentially going through a number of directories which you don't need to, and doing so on every request (thus, making loads of stat() calls). Solutions that come to my mind... -use a naming convention that dictates the directory name (similar to PEAR). Disadvantages: doesn't scale too great, resulting in horrible class names. -come up with some kind of pre-built array of the locations (propel does this for its __autoload). Disadvantage: requires a rebuild before any deploy of new code. -build the array "on the fly" and cache it. This seems to be the best solution, as it allows for any class names and directory structure you want, and is fully flexible in that new files just get added to the list. The concerns are: where to store it and what about deleted/moved files. For storage we chose APC, as it doesn't have the disk I/O overhead. With regards to file deletes, it doesn't matter, as you probably don't wanna require them anywhere anyway. As to moves... that's unresolved (we ignore it as historically it didn't happen very often for us). Any other solutions?

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  • How do I handle freeing unmanaged structures on application close?

    - by LostKaleb
    I have a C# project in which i use several unmanaged C++ functions. More so, I also have static IntPtr that I use as parameters for those functions. I know that whenever I use them, I should implement IDisposable in that class and use a destructor to invoke the Dispose method, where I free the used IntPtr, as is said in the MSDN page. public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } private void Dispose(bool disposing) { // Check to see if Dispose has already been called. if (!this.disposed) { if (disposing) { component.Dispose(); } CloseHandle(m_InstanceHandle); m_InstanceHandle = IntPtr.Zero; disposed = true; } } [System.Runtime.InteropServices.DllImport("Kernel32")] private extern static Boolean CloseHandle(IntPtr handle); However, when I terminate the application, I'm still left with a hanging process in TaskManager. I believe that it must be related to the used of the MarshalAs instruction in my structures: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; } When I create such a structure should I also be careful to free the space it allocs using a destructor? [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; ~SipxAudioCodec() { Marshal.FreeGlobal(something...); } }

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  • Counting character count in Access database column ins SQL

    - by jzr
    Good Evening. My problem is possibly very easy, I just have spent some time researching now and probably have a brain lock and unable to solve this, help would be much appreciated. database structure: col1 col2 col3 col4 ==================== 1233+4566+ABCD+CDEF 1233+4566+ACD1+CDEF 1233+4566+D1AF+CDEF I need to count character count in col3, wanted result in from the previous table would be: char count =========== A 3 B 1 C 2 D 3 F 1 1 2 is this possible to achieve by using SQL only? at the moment I am thinking of passing a parameter in to SQL query and count the characters one by one and then sum, however I did not start the VBA part yet, and frankly wouldn't want to do that. this is my query at the moment: PARAMETERS X Long; SELECT First(Mid(TABLE.col3,X,1)) AS [col3 Field], Count(Mid(TABLE.col3,X,1)) AS Dcount FROM TEST GROUP BY Mid(TABLE.col3,X,1) HAVING (((Count(Mid([TABLE].[col3],[X],1)))>=1)); ideas and help are much appreciated, as being said this is probably very for some of your guys, I don't usually work with access and SQL. Thanks.

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  • MySQL Datefields: duplicate or calculate?

    - by Konerak
    We are using a table with a structure imposed upon us more than 10 years ago. We are allowed to add columns, but urged not to change existing columns. Certain columns are meant to represent dates, but are put in different format. Amongst others: * CHAR(6): YYMMDD * CHAR(6): DDMMYY * CHAR(8): YYYYMMDD * CHAR(8): DDMMYYYY * DATE * DATETIME Since we now would like to do some more complex queries, using advanced date functions, my manager proposed to d*uplicate those problem columns* to a proper FORMATTED_OLDCOLUMNNAME column using a DATE or DATETIME format. Is this the way to go? Couldn't we just use the STR_TO_DATE function each time we accessed the columns? To avoid every query having to copy-paste the function, I could still work with a view or a stored procedure, but duplicating data to avoid recalculation sounds wrong. Solutions I see (I guess I prefer 2.2.1) 1. Physically duplicate columns 1.1 In the same table 1.1.1 Added by each script that does a modification (INSERT/UPDATE/REPLACE/...) 1.1.2 Maintained by a trigger on each modification 1.2 In a separate table 1.2.1 Added by each script that does a modification (INSERT/UPDATE/REPLACE/...) 1.2.2 Maintained by a trigger on each modification 2. On-demand transformation 2.1 Each query has to perform the transformation 2.1.1 Using copy-paste in the source code 2.1.2 Using a library 2.1.3 Using a STORED PROCEDURE 2.2 A view performs the transformation 2.2.1 A separate table replacing the entire table 2.2.2 A separate table just adding the date-fields for the primary keys Am I right to say it's better to recalculate than to store? And would a view be a good solution?

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  • R Tree 50,000 foot overview?

    - by roufamatic
    I'm working on a school project that involves taking a lat/long point and finding the top five closest points in a known list of places. The list is to be stored in memory, with the caveat that we must choose an "appropriate data structure" -- that is, we cannot simply store all the places in an array and compare distances one-by-one in a linear fashion. The teacher suggested grouping the place data by US State to prevent calculating the distance for places that are obviously too far away. I think I can do better. From my research online it seems like an R-Tree or one of its variants might be a neat solution. Unfortunately, that sentence is as far as I've gotten with understanding the actual technique, as the literature is simply too dense for my non-academic head. Can somebody give me a really high overview of what the process is for populating an R-Tree with lat/long data, and then traversing the tree to find those 5 nearest neighbors of a given point? Additionally the project is in C, and I don't have to reinvent the wheel on this, so if you've used an existing open source C implementation of an R Tree I'd be interested in your experiences.

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  • multiple models in Rails with a shared interface

    - by dfondente
    I'm not sure of the best structure for a particular situation in Rails. We have several types of workshops. The administration of the workshops is the same regardless of workshop type, so the data for the workshops is in a single model. We collect feedback from participants about the workshops, and the questionnaire is different for each type of workshop. I want to access the feedback about the workshop from the workshop model, but the class of the associated model will depend on the type of workshop. If I was doing this in something other than Rails, I would set up an abstract class for WorkshopFeedback, and then have subclasses for each type of workshop: WorkshopFeedbackOne, WorkshopFeedbackTwo, WorkshopFeedbackThree. I'm unsure how to best handle this with Rails. I currently have: class Workshop < ActiveRecord::Base has_many :workshop_feedbacks end class Feedback < ActiveRecord::Base belongs_to :workshop has_many :feedback_ones has_many :feedback_twos has_many :feedback_threes end class FeedbackOne < ActiveRecord::Base belongs_to :feedback end class FeedbackTwo < ActiveRecord::Base belongs_to :feedback end class FeedbackThree < ActiveRecord::Base belongs_to :feedback end This doesn't seem like to the cleanest way to access the feedback from the workshop model, as accessing the correct feedback will require logic investigating the Workshop type and then choosing, for instance, @workshop.feedback.feedback_one. Is there a better way to handle this situation? Would it be better to use a polymorphic association for feedback? Or maybe using a Module or Mixin for the shared Feedback interface? Note: I am avoiding using Single Table Inheritance here because the FeedbackOne, FeedbackTwo, FeedbackThree models do not share much common data, so I would end up with a large sparsely populated table with STI.

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  • Fast find object by string property

    - by Andrew Kalashnikov
    Hello, colleagues. I've got task to fast find object by its string property. Object: class DicDomain { public virtual string Id{ get; set; } public virtual string Name { get; set; } } For storing my object I use List[T] dictionary where T is DicDomain for now . I've got 5-10 such lists, which contain about 500-20000 at each one. Task is find objects by its Name. I use next code now: List<T> entities = dictionary.FindAll(s => s.Name.Equals(word, StringComparison.OrdinalIgnoreCase)); I've got some questions: Is my search speed optimal. I think now. Data structure. It List good for this task. What about hashtable,sorted... Method Find. May be i should use string intern?? I haven't much exp at these tasks. Can u give me good advice for increase perfomance. Thanks

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  • Background Image Overlapped Problem with jQuery

    - by Devyn
    Hi, Here is my working page. I attached buttons to white bishop and you can move around but left images are overlapped by right images. I think the problem is with CSS. The brief structure is here. <script> $(document).ready(function(){ $('#top').click(function(){ $('#p81').animate({top: "-=64px"}, 100); }); </script> <style> div.chess_board{ height: 512px; position: relative; width: 512px; } div.chess_square{ height:64px; position: absolute; width:64px; } div.chess_square.white { background: none repeat scroll 0 0 #ffffff; } . . . div.chess_piece{ background-image: url("sprite.png"); height: 64px; width: 64px; position: absolute; } div.chess_piece.bishot.white{ background-position: -64px 0; } </style> <div class="chess_board"> <div id="b81" class="chess_square white" style="top: 448px; left: 64px;"> <div class="chess_square_inner"></div> <div id="p81" class="chess_piece bishot white"></div> </div> </div> <input type="button" id="top" value="top" />

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  • IE7 - jquery addClass() breaks floating elements

    - by Patrick
    I have this nav that uses addClass('hover') when the mouse is rolled over an item. This works fine except in IE7 when the addClass function is called every element with float:left stops floating and the page totally loses its structure. This is my JS: _this.position_sub_menus = function(){ $('#header #nav > ul > li').mouseenter( function(e){ pos = $(this).offset(); height = $(this).height(); lvl2 = '#' + $(this).attr('id') + '-submenu'; if( $(this).position().left > ($('#nav').width()/2)){ pos.left = pos.left - $(lvl2).width() + $(this).width(); } $(this).addClass('hover'); $(lvl2).show(); $(lvl2).css( { 'left' : (pos.left - 12) + 'px', 'top' : pos.top + height + 'px'}); } ); This is the CSS of the of the elements that break: display: inline; float: left; margin-left: 10px; margin-right: 10px; position: relative; It's CSS from the 960 grid system. When I comment out the $(this).addClass('hover'); line the floated elements dont break. Is anyone familiar with this IE7 problem? Thanks guys

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  • Dimensions of a collection, and how to traverse it in an efficient, elegant manner

    - by Bruce Ferguson
    I'm trying to find an elegant way to deal with multi-dimensional collections in Scala. My understanding is that I can have up to a 5 dimensional collection using tabulate, such as in the case of the following 2-Dimensional array: val test = Array.tabulate[Double](row,col)(_+_) and that I can access the elements of the array using for(i<-0 until row) { for(j<-0 until col) { test(i)(j) = 0.0 } } If I don't know a priori what I'm going to be handling, what might be a succinct way of determining the structure of the collection, and spanning it, without doing something like: case(Array(x)) => for(i<-1 until dim1) { test(i) = 0.0 } case(Array(x,y)) => for(i<-1 until dim1) { for(j<-1 until dim2) { test(i)(j) = 0.0 } } case(Array(x,y,z)) => ... The dimensional values n1, n2, n3, etc... are private, right? Also, would one use the same trick of unwrapping a 2-D array into a 1-D vector when dealing with n-Dimensional objects if I want a single case to handle the traversal? Thanks in advance Bruce

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  • Codeigniter: how should I restructure db schema?

    - by Kevin Brown
    I don't even know if that's the right term. May it be known that I'm a major novice! I have three tables: users, profiles, and survey. Each one has user_id as it's first field, (auto-increment for users), and they're all tied by a foreign key constraint, CASCADE on DELETE. Currently, for each user, let's say user_id 1, they have a corresponding db entry in the other tables. For profiles it lists all their information, and the survey table holds all their survey information. Now I must change things...darn scope creep. Users need the ability to have multiple survey results. I imagine that this would be similar to a comment table for a blog... My entire app runs around the idea that a single user is linked to a constraining profile and survey. How should I structure my db? How should I design my app's db so that a user can have multiple tests/profiles for the test? Please assist! Any advice, information and personal-knowledge is appreciated! Right now the only way I know how to accompany my client is to create a pseudo-user for each test (so unnecessary) and list them in a view table (called "your tests")-- these are obtained from the db by saying: where user_id=manager_id

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  • Single-entry implementation gone wrong

    - by user745434
    I'm doing my first single-entry site and based on the result, I can't see the benefit. I've implemented the following: .htaccess redirects all requests to index.php at the root Url is parsed and each /segment/ is stored as an element in an array First segment indicates which folder to include (e.g. "users" » "/pages/users/index.php"). index.php file of each folder parses the remaining elements in the segments array until array is empty. content.php file of each folder is included if there are no more elements in the segments array, indicating that the destination file is reached Sample File structure ( folders in [] ): [root] index.php [pages] [users] index.php content.php [profile] index.php content.php [edit] index.php content.php [other-page] index.php content.php Request: http://mysite.com/users/profile/ .htaccess redirects request to http://mysite.com/index.php URL is parsed and segments array contains: [1] users, [2] profile index.php maps [1] to "pages/users/index.php", so includes that file pages/users/index.php maps [2] to pages/users/profile/index.php, so includes that file Since no other elements in the segments array, the contents.php file in the current folder (pages/users/profile) is included. I'm not really seeing the benefit of doing this over having functions that include components of the site (e.g. include_header(), include_footer(), etc.), so I conclude that I'm doing something terribly wrong. I'm just not sure what it is.

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  • Help on MySQL table indexing when GROUP BY is used in a query

    - by Silver Light
    Thank you for your attention. There are two INNODB tables: Table authors id INT nickname VARCHAR(50) status ENUM('active', 'blocked') about TEXT Table books author_id INT title VARCHAR(150) I'm running a query against these tables, to get each author and a count of books he has: SELECT a. * , COUNT( b.id ) AS book_count FROM authors AS a, books AS b WHERE a.status != 'blocked' AND b.author_id = a.id GROUP BY a.id ORDER BY a.nickname This query is very slow (takes about 6 seconds to execute). I have an index on books.author_id and it works perfectly, but I do not know how to create an index on authors table, so that this query could use it. Here is how current EXPLAIN looks: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE a ALL PRIMARY,id_status_nickname NULL NULL NULL 3305 Using where; Using temporary; Using filesort 1 SIMPLE b ref key_author_id key_author_id 5 a.id 2 Using where; Using index I've looked at MySQL manual on optimizing queries with group by, but could not figure out how I can apply it on my query. I'll appreciate any help and hints on this - what must be the index structure, so that MySQL could use it?

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  • Counting a cell up per Objects

    - by Auro
    hey i got a problem once again :D a little info first: im trying to copy data from one table to an other table(structure is the same). now one cell needs to be incremented, beginns per group at 1 (just like a histroy). i have this table: create table My_Test/My_Test2 ( my_Id Number(8,0), my_Num Number(6,0), my_Data Varchar2(100)); (my_Id, my_Num is a nested PK) if i want to insert a new row, i need to check if the value in my_id already exists. if this is true then i need to use the next my_Num for this Id. i have this in my Table: My_Id My_Num My_Data 1 1 'test1' 1 2 'test2' 2 1 'test3' if i add now a row for my_Id 1, the row would look like this: i have this in my Table: My_Id My_Num My_Data 1 3 'test4' this sounds pretty easy ,now i need to make it in a SQL and on SQL Server i had the same problem and i used this: Insert Into My_Test (My_Id,My_Num,My_Data) SELECT my_Id, ( SELECT CASE ( CASE MAX(a.my_Num) WHEN NULL THEN 0 Else Max(A.My_Num) END) + b.My_Num WHEN NULL THEN 1 ELSE ( CASE MAX(a.My_Num) WHEN NULL THEN 0 Else Max(A.My_Num) END) + b.My_Num END From My_Test A where my_id = 1 ) ,My_Data From My_Test2 B where my_id = 1; this Select gives null back if no Rows are found in the subselect is there a way so i could use max in the case? and if it give null back it should use 0 or 1? greets Auro

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  • Within a DLL, how is the function table structured?

    - by Willi Ballenthin
    I've been looking into the implementation of a device library that doesn't explicitly support my operating system. In particular, I have a disassembled DLL, and a fair amount of supporting source code. Now, how is the function table/export table structured? My understanding is that the first structure of the .data section is a table of VRAs. Next is a table of strings linked by index to that first address table. This makes sense to me, as a linker could translate between symbols and addresses. How do functions referenced by ordinals fit into this picture? How does one know which function has such and such ordinal number, and how does the linker resolve this? In other words, given that some other DLL imports SOME_LIBRARY_ordinal_7, how does the linker know which function to work with? Thanks, all! edit More information... Im working with the FTDI libraries, and would like to resolve which function is being invoked. In particular, I see something like: extern FTD2XX_Ordinal_28: near how might I go about determining which function is being referenced, and how does the linker do this?

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  • How to have variables with dynamic data types in Java?

    - by Nazgulled
    Hi, I need to have a UserProfile class that it's just that, a user profile. This user profile has some vital user data of course, but it also needs to have lists of messages sent from the user friends. I need to save these messages in LinkedList, ArrayList, HashMap and TreeMap. But only one at a time and not duplicate the message for each data structure. Basically, something like a dynamic variable type where I could pick the data type for the messages. Is this, somehow, possible in Java? Or my best approach is something like this? I mean, have 2 different classes (for the user profile), one where I host the messages as Map<K,V> (and then I use HashMap and TreeMap where appropriately) and another class where I host them as List<E> (and then I use LinkedList and ArrayList where appropriately). And probably use a super class for the UserProfile so I don't have to duplicate variables and methods for fields like data, age, address, etc... Any thoughts?

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  • Pass Arguments to Included Module in Ruby?

    - by viatropos
    I'm hoping to implement something like all of the great plugins out there for ruby, so that you can do this: acts_as_commentable has_attached_file :avatar But I have one constraint: That helper method can only include a module; it can't define any variables or methods. The reason for this is because, I want the options hash to define something like type, and that could be converted into one of say 20 different 'workhorse' modules, all of which I could sum up in a line like this: def dynamic_method(options = {}) include ("My::Helpers::#{options[:type].to_s.camelize}").constantize(options) end Then those 'workhorses' would handle the options, doing things like: has_many "#{options[:something]}" Here's what the structure looks like, and I'm wondering if you know the missing piece in the puzzle: # 1 - The workhorse, encapsuling all dynamic variables module My::Module def self.included(base) base.extend ClassMethods base.class_eval do include InstanceMethods end end module InstanceMethods self.instance_eval %Q? def #{options[:my_method]} "world!" end ? end module ClassMethods end end # 2 - all this does is define that helper method module HelperModule def self.included(base) base.extend(ClassMethods) end module ClassMethods def dynamic_method(options = {}) # don't know how to get options through! include My::Module(options) end end end # 3 - send it to active_record ActiveRecord::Base.send(:include, HelperModule) # 4 - what it looks like class TestClass < ActiveRecord::Base dynamic_method :my_method => "hello" end puts TestClass.new.hello #=> "world!" That %Q? I'm not totally sure how to use, but I'm basically just wanting to somehow be able to pass the options hash from that helper method into the workhorse module. Is that possible? That way, the workhorse module could define all sorts of functionality, but I could name the variables whatever I wanted at runtime.

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