business logic - Page 551

Why are there so many man-made edge cases in IT, and is there any hope for simplification / unificat

- by Hamish Grubijan

This question is meant to generate discussion and so it is marked as community wiki. My observation is that the field of information technology grows so rapidly and randomly, that for many it takes a lot of time to learn many intricacies of some tools that will be obsolete in just short 3 years. If you look at the questions asked on StackOverflow ... at least half of them stem from the fact that some language / tool / API / protocol was poorly designed, is backwards and has gotchas. There are so many things which distract developers from converting English into machine code; instead they spend their time configuring stuff and gluing together things that do not really fit. How many times do you pick up somebody else's project (or someone picks up yours :) ) and realize that this program does not need half of the dialogs that it has, and that the logic can be simplified a great deal? But, it had to be made and sold here before a better thing is made and sold elsewhere, and hence all this rush. I often wish that things would just slow down. I do not want Microsoft Windows to run on my car's computer, my watch, my table, my toaster oven, and my toilet seat. I'd rather have Windows that DOES NOT HAVE WINDOWS REGISTRY, I'd rather have Windows that allows two different programs to work on the same file at the same time, the way it works on Unix systems. Microsoft is just an example. I am looking forward to the day when I do not have to worry about Windows vs Unix new line break, when System32 actually means that this directory contains 32-bit binaries, and not 64-bit ones, the day when dll hell and manifest hell are no longer an issue, the day when it takes me a lot less than 3 months on a new job to learn the system. I do not mean learning the entire code base of a product (depending on the size of it, it can take a long time). I mean - remembering which build-assisting scripts are written in Perl and which version of it, and which ones are done through .bat files, when do I need to manually make every file in some directory writable before running a script, or else a critical step of a database maintenance home-grown tool will bomb, and it will take 2 days to clean that up. Makes me wonder if humans enslaved computers, or if it is the other way around. The key is that improving those things will not bring extra revenue, and hence those taking the time to fix crap like that are not "business focused". However, these imperfections irritate me immensely, particularly because my memory is limited - I can hold only a small portion of that useless knowledge of a system in my head at any given point in time. I must not be alone. Did you also happen to notice that a programmer can waste a lot of time on things that should have been a lot more straight-forward? Is there hope? Will things get better/simpler in the future, or will there be a lot more IT crap floating around? I suppose I see diversity of tools, protocols, etc. as a bad thing. Thank you for participation.

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Need help with memory leaks in RSS Reader

- by Stilton

I'm trying to write a simple RSS reader for the iPhone, and it appeared to be working fine, until I started working with Instruments, and discovered my App is leaking massive amounts of memory. I'm using the NSXMLParser class to parse an RSS feed. My memory leaks appear to be originating from the overridden delegate methods: - (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string and - (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName I'm also suspicious of the code that populates the cells from my parsed data, I've included the code from those methods and a few other key ones, any insights would be greatly appreciated. - (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string { if ([self.currentElement isEqualToString:@"title"]) { [self.currentTitle appendString:string]; } else if ([self.currentElement isEqualToString:@"link"]) { [self.currentURL appendString:string]; } else if ([self.currentElement isEqualToString:@"description"]) { [self.currentSummary appendString:string]; } } - (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName { if ([elementName isEqualToString:@"item"]) { //asdf NSMutableDictionary *item = [[NSMutableDictionary alloc] init]; [item setObject:currentTitle forKey:@"title"]; [item setObject:currentURL forKey:@"URL"]; [item setObject:currentSummary forKey:@"summary"]; [self.currentTitle release]; [self.currentURL release]; [self.currentSummary release]; [self.stories addObject:item]; [item release]; } } // Customize the appearance of table view cells. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } // Configure the cell. // Set up the cell int index = [indexPath indexAtPosition: [indexPath length] - 1]; CGRect contentRect = CGRectMake(8.0, 4.0, 260, 20); UILabel *textLabel = [[UILabel alloc] initWithFrame:contentRect]; if (self.currentLevel == 0) { textLabel.text = [self.categories objectAtIndex: index]; } else { textLabel.text = [[self.stories objectAtIndex: index] objectForKey:@"title"]; } textLabel.textColor = [UIColor blackColor]; textLabel.font = [UIFont boldSystemFontOfSize:14]; [[cell contentView] addSubview: textLabel]; //[cell setText:[[stories objectAtIndex: storyIndex] objectForKey: @"title"]]; [textLabel autorelease]; return cell; } - (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict { if ([elementName isEqualToString:@"item"]) { self.currentTitle = [[NSMutableString alloc] init]; self.currentURL = [[NSMutableString alloc] init]; self.currentSummary = [[NSMutableString alloc] init]; } if (currentElement != nil) { [self.currentElement release]; } self.currentElement = [elementName copy]; } - (void)dealloc { [currentElement release]; [currentTitle release]; [currentURL release]; [currentSummary release]; [currentDate release]; [stories release]; [rssParser release]; [storyTable release]; [super dealloc]; } // Override to support row selection in the table view. - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { // Navigation logic may go here -- for example, create and push another view controller. // AnotherViewController *anotherViewController = [[AnotherViewController alloc] initWithNibName:@"AnotherView" bundle:nil]; int index = [indexPath indexAtPosition: [indexPath length] - 1]; if (currentLevel == 1) { StoryViewController *storyViewController = [[StoryViewController alloc] initWithURL:[[stories objectAtIndex: index] objectForKey:@"URL"] nibName:@"StoryViewController" bundle:nil]; [self.navigationController pushViewController:storyViewController animated:YES]; [storyViewController release]; } else { RootViewController *rvController = [[RootViewController alloc] initWithNibName:@"RootViewController" bundle:nil]; rvController.currentLevel = currentLevel + 1; rvController.rssIndex = index; [self.navigationController pushViewController:rvController animated:YES]; [rvController release]; } }

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Mysql - Help me alter this search query involving multiple joins and conditions to get the desired r

- by sandeepan-nath

About the system - We are following tags based search. Tutors create packs - tag relations for tutors stored in tutors_tag_relations and those for packs stored in learning_packs_tag_relations. All tags are stored in tags table. The system has 6 tables - tutors, Users (linked to tutor_details), learning_packs, learning_packs_tag_relations, tutors_tag_relations and tags Please run the following fresh queries to setup the system :- CREATE TABLE IF NOT EXISTS learning_packs_tag_relations ( id_tag int(10) unsigned NOT NULL DEFAULT '0', id_tutor int(10) DEFAULT NULL, id_lp int(10) unsigned DEFAULT NULL, KEY Learning_Packs_Tag_Relations_FKIndex1 (id_tag), KEY id_lp (id_lp), KEY id_tag (id_tag) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; CREATE TABLE IF NOT EXISTS learning_packs ( id_lp int(10) unsigned NOT NULL AUTO_INCREMENT, id_status int(10) unsigned NOT NULL DEFAULT '2', id_author int(10) unsigned NOT NULL DEFAULT '0', name varchar(255) NOT NULL DEFAULT '', PRIMARY KEY (id_lp) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=21 ; CREATE TABLE IF NOT EXISTS tutors_tag_relations ( id_tag int(10) unsigned NOT NULL DEFAULT '0', id_tutor int(10) DEFAULT NULL, KEY Tutors_Tag_Relations (id_tag), KEY id_tutor (id_tutor), KEY id_tag (id_tag) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; CREATE TABLE IF NOT EXISTS users ( id_user int(10) unsigned NOT NULL AUTO_INCREMENT, name varchar(100) NOT NULL DEFAULT '', surname varchar(155) NOT NULL DEFAULT '', PRIMARY KEY (id_user) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=52 ; CREATE TABLE IF NOT EXISTS tutor_details ( id_tutor int(10) NOT NULL AUTO_INCREMENT, id_user int(10) NOT NULL, PRIMARY KEY (id_tutor) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=60 ; CREATE TABLE IF NOT EXISTS tags ( id_tag int(10) unsigned NOT NULL AUTO_INCREMENT, tag varchar(255) DEFAULT NULL, PRIMARY KEY (id_tag), UNIQUE KEY tag (tag) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ; ALTER TABLE learning_packs_tag_relations ADD CONSTRAINT Learning_Packs_Tag_Relations_ibfk_1 FOREIGN KEY (id_tag) REFERENCES tags (id_tag) ON DELETE NO ACTION ON UPDATE NO ACTION; ALTER TABLE learning_packs ADD CONSTRAINT Learning_Packs_ibfk_2 FOREIGN KEY (id_author) REFERENCES users (id_user) ON DELETE NO ACTION ON UPDATE NO ACTION; ALTER TABLE tutors_tag_relations ADD CONSTRAINT Tutors_Tag_Relations_ibfk_1 FOREIGN KEY (id_tag) REFERENCES tags (id_tag) ON DELETE NO ACTION ON UPDATE NO ACTION; INSERT INTO test.users ( id_user , name , surname ) VALUES ( NULL , 'Vivian', 'Richards' ), ( NULL , 'Sachin', 'Tendulkar' ); INSERT INTO test.users ( id_user , name , surname ) VALUES ( NULL , 'Don', 'Bradman' ); INSERT INTO test.tutor_details ( id_tutor , id_user ) VALUES ( NULL , '52' ), ( NULL , '53' ); INSERT INTO test.tutor_details ( id_tutor , id_user ) VALUES ( NULL , '54' ); INSERT INTO test.tags ( id_tag , tag ) VALUES ( 1 , 'Vivian' ), ( 2 , 'Richards' ); INSERT INTO test.tags (id_tag, tag) VALUES (3, 'Sachin'), (4, 'Tendulkar'); INSERT INTO test.tags (id_tag, tag) VALUES (5, 'Don'), (6, 'Bradman'); INSERT INTO test.learning_packs (id_lp, id_status, id_author, name) VALUES ('1', '1', '52', 'Cricket 1'), ('2', '2', '52', 'Cricket 2'); INSERT INTO test.tags (id_tag, tag) VALUES ('7', 'Cricket'), ('8', '1'); INSERT INTO test.tags (id_tag, tag) VALUES ('9', '2'); INSERT INTO test.learning_packs_tag_relations (id_tag, id_tutor, id_lp) VALUES ('7', '52', '1'), ('8', '52', '1'); INSERT INTO test.learning_packs_tag_relations (id_tag, id_tutor, id_lp) VALUES ('7', '52', '2'), ('9', '52', '2'); =================================================================================== Requirement Now I want to search learning_packs, with the same AND logic. Help me modify the following query so that searching pack name or tutor's name, surname results all active packs (either directly those packs or packs created by those tutors). ================================================================================== select lp.* from Learning_Packs AS lp LEFT JOIN Learning_Packs_Tag_Relations AS lptagrels ON lp.id_lp = lptagrels.id_lp LEFT JOIN Tutors_Tag_Relations as ttagrels ON lp.id_author = ttagrels.id_tutor LEFT JOIN Tutor_Details AS td ON ttagrels.id_tutor = td.id_tutor LEFT JOIN Users as u on td.id_user = u.id_user JOIN Tags as t on (t.id_tag = lptagrels.id_tag) or (t.id_tag = ttagrels.id_tag) where lp.id_status = 1 AND ( t.tag LIKE "%Vivian%" OR t.tag LIKE "%Richards%" ) group by lp.id_lp HAVING count(lp.id_lp) 1 limit 0,20 As you can see, searching "Cricket 1" returns that pack but searching Vivian Richards does not return the same pack. Please help

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translating play in HTML to python

- by aharon

So, I'd like to represent one of Shakespeare's plays, Hamlet, into the following objects (maybe this isn't the best representation, if so please tell me): class Play(): acts = [] ... def add_act(self, act): acts.append(act) class Act(): scenes = [] ... def add_scene(self, scene): scenes.append(scene) class Scene(): elems = [] def __init__(self, title, setting=""): ... def add_elem(self, elem): elems.append(elem) ... class StageDirection(): # elem def __init__(self, text): ... class Line(): # elem def __init__(self, id, text, character = None): ... # A None character represents a continuation from the previous line # id could be, for example, 1.1.1 There are other methods, of course, for printing and such in each of the classes. The question is, how do I get a structure based on these classes (or something like them) from HTML 4 code that looks like this: <H3>ACT I</h3> <h3>SCENE I. Elsinore. A platform before the castle.</h3> <p><blockquote> <i>FRANCISCO at his post. Enter to him BERNARDO</i> </blockquote> <A NAME=speech1><b>BERNARDO</b></a> <blockquote> <A NAME=1.1.1>Who's there?</A><br> </blockquote> <A NAME=speech2><b>FRANCISCO</b></a> <blockquote> <A NAME=1.1.2>Nay, answer me: stand, and unfold yourself.</A><br> </blockquote> <A NAME=speech3><b>BERNARDO</b></a> <blockquote> <A NAME=1.1.3>Long live the king!</A><br> </blockquote> <A NAME=speech4><b>FRANCISCO</b></a> <blockquote> <A NAME=1.1.4>Bernardo?</A><br> </blockquote> <A NAME=speech5><b>BERNARDO</b></a> <blockquote> <A NAME=1.1.5>He.</A><br> </blockquote>  translating that into something like this: play = Play() actI = Act() sceneI = Scene("Scene I", "Elsinore. A platform before the castle.") sceneI.add_elem(StageDirection("Francisco at his post. Enter to him Bernardo.")) sceneI.add_elem(Line("Bernardo", "Who's there?")) ... Of course, I don't expect all the code—but what libraries and, when there aren't libraries, logic should I use? Thanks. (This is for a future opensource project and me learning Python for fun—not homework.)

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Choosing the right .NET architecture. WCF? WPF/Forms, ASP.NET (MVC)?

- by Tommy Jakobsen

I’m in the situation that I have to design and implement a rather big system from the bottom. I’m having some (a lot actually) questions about the architecture that I would like your comments and thoughts on. I don’t hope that I’ve written too much here, but I wanted to give you all an idea of what the system is. Quick info about the applications, read if you want: I can’t share much detail about the project, but basically it’s a system where we offer our customer a service to manage their users. We have a hotline where the users call and our hotline uses an (windows) application (intranet) to manage the user’s data, etc. The customer also has a web application where they can see reports, information about their business and users, and the ability to modify their data. Modifying data is not just user data like address and so, but also information about the products/services the user has, which can be complicated. The applications will be built on Microsoft .NET Framework 4, with a MS SQL Server 2008 database. There will be a few applications that have to access this database, such as: Intranet application (used by us and our hotline) Customer web application type 1 Customer web application type 2 Customer web application type n different applications) … Now my big problem is what .NET parts I should use for such a system. For the “backend” I’ve considered using Windows Communication Foundation: Would WCF be a good choice? The intranet application will be an application that has to edit lots of records in the database. It has to be easy to navigate using the keyboard (fast to work with). Has a feature such as “find customer, find that, lookup this, choose this and update that”. What would be the best choice to develop this application in? Would it be WPF or good old Windows Forms? I don’t need all of the fancy graphics features in WPF, like 3D, but the application has to look nice (maybe something like the new Visual Studio/Office tools). And the same question goes for the web pages. They have much the same work to do, but not as many features as the intranet application, and not the same amount of data (much less). That is my questions for now. I’m hoping to get a discussion going that will open my eyes to some of these technologies, helping me decide architecture to go with. I would like to say thanks in advance, and let you all know that any thoughts will be much appreciated.

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Combinations and Permutations in F#

- by Noldorin

I've recently written the following combinations and permutations functions for an F# project, but I'm quite aware they're far from optimised. /// Rotates a list by one place forward. let rotate lst = List.tail lst @ [List.head lst] /// Gets all rotations of a list. let getRotations lst = let rec getAll lst i = if i = 0 then [] else lst :: (getAll (rotate lst) (i - 1)) getAll lst (List.length lst) /// Gets all permutations (without repetition) of specified length from a list. let rec getPerms n lst = match n, lst with | 0, _ -> seq [[]] | _, [] -> seq [] | k, _ -> lst |> getRotations |> Seq.collect (fun r -> Seq.map ((@) [List.head r]) (getPerms (k - 1) (List.tail r))) /// Gets all permutations (with repetition) of specified length from a list. let rec getPermsWithRep n lst = match n, lst with | 0, _ -> seq [[]] | _, [] -> seq [] | k, _ -> lst |> Seq.collect (fun x -> Seq.map ((@) [x]) (getPermsWithRep (k - 1) lst)) // equivalent: | k, _ -> lst |> getRotations |> Seq.collect (fun r -> List.map ((@) [List.head r]) (getPermsWithRep (k - 1) r)) /// Gets all combinations (without repetition) of specified length from a list. let rec getCombs n lst = match n, lst with | 0, _ -> seq [[]] | _, [] -> seq [] | k, (x :: xs) -> Seq.append (Seq.map ((@) [x]) (getCombs (k - 1) xs)) (getCombs k xs) /// Gets all combinations (with repetition) of specified length from a list. let rec getCombsWithRep n lst = match n, lst with | 0, _ -> seq [[]] | _, [] -> seq [] | k, (x :: xs) -> Seq.append (Seq.map ((@) [x]) (getCombsWithRep (k - 1) lst)) (getCombsWithRep k xs) Does anyone have any suggestions for how these functions (algorithms) can be sped up? I'm particularly interested in how the permutation (with and without repetition) ones can be improved. The business involving rotations of lists doesn't look too efficient to me in retrospect. Update Here's my new implementation for the getPerms function, inspired by Tomas's answer. Unfortunately, it's not really any fast than the existing one. Suggestions? let getPerms n lst = let rec getPermsImpl acc n lst = seq { match n, lst with | k, x :: xs -> if k > 0 then for r in getRotations lst do yield! getPermsImpl (List.head r :: acc) (k - 1) (List.tail r) if k >= 0 then yield! getPermsImpl acc k [] | 0, [] -> yield acc | _, [] -> () } getPermsImpl List.empty n lst

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WTF is wtf? (in WebKit code base)

- by Motti

I downloaded Chromium's code base and ran across the WTF namespace. namespace WTF { /* * C++'s idea of a reinterpret_cast lacks sufficient cojones. */ template<typename TO, typename FROM> TO bitwise_cast(FROM in) { COMPILE_ASSERT(sizeof(TO) == sizeof(FROM), WTF_wtf_reinterpret_cast_sizeof_types_is_equal); union { FROM from; TO to; } u; u.from = in; return u.to; } } // namespace WTF Does this mean what I think it means? Could be so, the bitwise_cast implementation specified here will not compile if either TO or FROM is not a POD and is not (AFAIK) more powerful than C++ built in reinterpret_cast. The only point of light I see here is the nobody seems to be using bitwise_cast in the Chromium project. I see there's some legalese so I'll put in the little letters to keep out of trouble. /* * Copyright (C) 2008 Apple Inc. All Rights Reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */

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JavaScript accessing form elements using document.forms[].elements[]

- by thecoshman

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Slicing a time range into parts

- by beporter

First question. Be gentle. I'm working on software that tracks technicians' time spent working on tasks. The software needs to be enhanced to recognize different billable rate multipliers based on the day of the week and the time of day. (For example, "Time and a half after 5 PM on weekdays.") The tech using the software is only required to log the date, his start time and his stop time (in hours and minutes). The software is expected to break the time entry into parts at the boundaries of when the rate multipliers change. A single time entry is not permitted to span multiple days. Here is a partial sample of the rate table. The first-level array keys are the days of the week, obviously. The second-level array keys represent the time of the day when the new multiplier kicks in, and runs until the next sequential entry in the array. The array values are the multiplier for that time range. [rateTable] => Array ( [Monday] => Array ( [00:00:00] => 1.5 [08:00:00] => 1 [17:00:00] => 1.5 [23:59:59] => 1 ) [Tuesday] => Array ( [00:00:00] => 1.5 [08:00:00] => 1 [17:00:00] => 1.5 [23:59:59] => 1 ) ... ) In plain English, this represents a time-and-a-half rate from midnight to 8 am, regular rate from 8 to 5 pm, and time-and-a-half again from 5 till 11:59 pm. The time that these breaks occur may be arbitrary to the second and there can be an arbitrary number of them for each day. (This format is entirely negotiable, but my goal is to make it as easily human-readable as possible.) As an example: a time entry logged on Monday from 15:00:00 (3 PM) to 21:00:00 (9 PM) would consist of 2 hours billed at 1x and 4 hours billed at 1.5x. It is also possible for a single time entry to span multiple breaks. Using the example rateTable above, a time entry from 6 AM to 9 PM would have 3 sub-ranges from 6-8 AM @ 1.5x, 8AM-5PM @ 1x, and 5-9 PM @ 1.5x. By contrast, it's also possible that a time entry may only be from 08:15:00 to 08:30:00 and be entirely encompassed in the range of a single multiplier. I could really use some help coding up some PHP (or at least devising an algorithm) that can take a day of the week, a start time and a stop time and parse into into the required subparts. It would be ideal to have the output be an array that consists of multiple entries for a (start,stop,multiplier) triplet. For the above example, the output would be: [output] => Array ( [0] => Array ( [start] => 15:00:00 [stop] => 17:00:00 [multiplier] => 1 ) [1] => Array ( [start] => 17:00:00 [stop] => 21:00:00 [multiplier] => 1.5 ) ) I just plain can't wrap my head around the logic of splitting a single (start,stop) into (potentially) multiple subparts.

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jQuery line 67 saying "TypeError: 'undefined' is not a function."

- by dfdf

var dbShell; function doLog(s){ /* setTimeout(function(){ console.log(s); }, 3000); */ } function dbErrorHandler(err){ alert("DB Error: "+err.message + "\nCode="+err.code); } function phoneReady(){ doLog("phoneReady"); //First, open our db dbShell = window.openDatabase("SimpleNotes", 2, "SimpleNotes", 1000000); doLog("db was opened"); //run transaction to create initial tables dbShell.transaction(setupTable,dbErrorHandler,getEntries); doLog("ran setup"); } //I just create our initial table - all one of em function setupTable(tx){ doLog("before execute sql..."); tx.executeSql("CREATE TABLE IF NOT EXISTS notes(id INTEGER PRIMARY KEY,title,body,updated)"); doLog("after execute sql..."); } //I handle getting entries from the db function getEntries() { //doLog("get entries"); dbShell.transaction(function(tx) { tx.executeSql("select id, title, body, updated from notes order by updated desc",[],renderEntries,dbErrorHandler); }, dbErrorHandler); } function renderEntries(tx,results){ doLog("render entries"); if (results.rows.length == 0) { $("#mainContent").html("<p>You currently do not have any notes.</p>"); } else { var s = ""; for(var i=0; i<results.rows.length; i++) { s += "<li><a href='edit.html?id="+results.rows.item(i).id + "'>" + results.rows.item(i).title + "</a></li>"; } $("#noteTitleList").html(s); $("#noteTitleList").listview("refresh"); } } function saveNote(note, cb) { //Sometimes you may want to jot down something quickly.... if(note.title == "") note.title = "[No Title]"; dbShell.transaction(function(tx) { if(note.id == "") tx.executeSql("insert into notes(title,body,updated) values(?,?,?)",[note.title,note.body, new Date()]); else tx.executeSql("update notes set title=?, body=?, updated=? where id=?",[note.title,note.body, new Date(), note.id]); }, dbErrorHandler,cb); } function init(){ document.addEventListener("deviceready", phoneReady, false); //handle form submission of a new/old note $("#editNoteForm").live("submit",function(e) { var data = {title:$("#noteTitle").val(), body:$("#noteBody").val(), id:$("#noteId").val() }; saveNote(data,function() { $.mobile.changePage("index.html",{reverse:true}); }); e.preventDefault(); }); //will run after initial show - handles regetting the list $("#homePage").live("pageshow", function() { getEntries(); }); //edit page logic needs to know to get old record (possible) $("#editPage").live("pageshow", function() { var loc = $(this).data("url"); if(loc.indexOf("?") >= 0) { var qs = loc.substr(loc.indexOf("?")+1,loc.length); var noteId = qs.split("=")[1]; //load the values $("#editFormSubmitButton").attr("disabled","disabled"); dbShell.transaction( function(tx) { tx.executeSql("select id,title,body from notes where id=?",[noteId],function(tx,results) { $("#noteId").val(results.rows.item(0).id); $("#noteTitle").val(results.rows.item(0).title); $("#noteBody").val(results.rows.item(0).body); $("#editFormSubmitButton").removeAttr("disabled"); }); }, dbErrorHandler); } else { $("#editFormSubmitButton").removeAttr("disabled"); } }); } Dats my code, awfully long, huh? Well anyways I got most of it from here, however I get an error on line 67 saying "TypeError: 'undefined' is not a function.". I'm using Steroids (phonegap-like) and testing dis on an iPhone simulator. I'm sure it uses some cordova for the database work. Thank you for your help :-)

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surfaceDestroyed called out of turn

- by Avasulthiris

I'm currently developing on minimum sdk version 3 (Android 1.5 - cupcake) and I'm having a strange unexplained issue that I have not been able to solve on my own. It is now becoming a rather urgent issue as I've already missed 1 deadline... I'm writing a high-level library to make long term android development easier and quicker. The one specific module has to capture images for a application... I've gotten everything right so far over the last couple months, except this one little thing and I don't know what to do any more: When I use the Camera object and implement a SurfaceHolder.Callback, the methods surfaceCreated() and surfaceChanged() are called one after the other. Then when the activity finishes, surfaceDestroyed() is called. This is how it should be, but when I stick the exact same code in my library (plain Java library that references the Android API - not in an activity), surfaceDestroyed() is called directly after created and changed. As a result - the camera object is closed before I can use it and the application force closes. What a pain. I can't do anything! This method call is controlled by the device.. Why does the surface close for no reason? Even when I post it to run on the activity thread through my own invokeAndWait(Runnable) method, like I do for many other things. I have 5 different working examples of different ways and implementations of capturing images in android but I still get the same issue when I plug it into my library. I don't understand what the difference is. The code is pretty much the same - and I post all the related code to the UI thread so its not a thread handling issue or anything like that. I've rewritten it about 20 times in different ways - same issue every time.. The only other way to approach it that I know of is creating a new Camera and setting it to the VideoView. The android source (c++ native code) however provides no Camera constructor, only an open() method which automatically forwards the camera's state to 'prepared' but I can only set the camera to the VideoView from the 'initialized' state. Pretty silly, I know, but there is no way around it unless I modify the Android library source code haha. not an option! The API does not allow for this method - you are expected to use it like my first example. So essentially - i just need to understand exactly why surfaceDestroyed() is called out of turn and if there is anything I can do to avoid it closing? If i can just understand the exact logic behind it and how it works! The documentation isn't much help! Secondly, if someone knows of any alternative ways to do it, as my second example, but hopefully one which the API actually allows for? haha Thanks guys. I would post code, but its fairly complicated, a couple thousand lines for this specific class and it would probably take a couple days to explain with all the threading and event listeners and what not. I just need help with this 1 single thing. Please let me know if you have any questions.

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How to catch 'exceptions' for out of order execution in Workflow Foundation 4?

- by Alex Key

Hi, I am attempting to model a worklfow using a "WCF Workflow Service" in .net / vs 2010 that needs to handle out of order execution gracefully (but not allow it - if thath makes sense!?) For example I have 2 receive activities one called Initialize and the other called GetValue inside a FlowChart. In most cases Initialize should be called first and GetValue after (as modled in the flow chart). However if GetValue is executed before Initialize I do not want to return an "out of order" exception (although when I look at the WCF test client, I can't actually see an exception). But instead a custom exception saying something like "you must initialize first". In theory I could model this with lots of parallel activities and conditions to check if Initialized / Running / Terminated etc. But the business process I am modelling if very very similar to a state machine... except it must handle people executing things in the wrong order. Ideally I would like to catch the "out of order" exception (thought I don't think it's really an exception as such), check the 'exception' to see which function was attempted to run and then handle it. I have done some research around enabling AllowBufferedReceive. However I don't want to be able to execute out of order (I don't think), but instead give a detailed response if it does happen. I've looked at the new beta state machine template for WF 4 - but i'm not sure if it does what i'm after? I'm not sure if I have the wrong end of the stick, so any help would be greatly appreciated. [EDIT] To help clarify... Sorry it's a tricky one to explain. The standard I am trying to implement (the e-learning standard SCORM RTE) is structured like a state machine i.e. certain functions can only be executed in certain states. However the standard specifies that if the calling clients tries to execute a function that it is not meant to, then a warning should be issued... for example "you cannot use GetValue(), because you have not yet Initialized". Ideally I'd like to structure the workflow as the theoretical state machine and not need to have to use multiple if/else's to handle all the scenarios where something could be executed out-of-order. I'd like to catch a out-of-order exception (but I don't think there is such an exception - as it's not in the debugger) and rethrow it.

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Retreiving dynamic post values

- by Pankaj Khurana

Hi I am using tiny table with some input fields for posting in a page. I want to retrieve the data which the user fills up for a particular instrument number. My code <form name="frmDeposit" action="paymentdeposited.php" method="post"> <table cellpadding="0" cellspacing="0" border="0" id="table" class="tinytable" style="width:700px;"> <thead> <tr> <th><h3>Email</h3></th> <th><h3>Amount Paid</h3></th> <th><h3>Instrument Type</h3></th> <th><h3>Instrument No.</h3></th> <th><h3>Date Paid</h3></th> <th class="nosort"><h3>Date Deposited</h3></th> <th class="nosort"><h3>Bank Name</h3></th> <th class="nosort"><h3>Slip No.</h3></th> <th class="nosort"><h3>Submit</h3></th> </tr> </thead> <tbody> <?php foreach($paymentsdeposited as $paymentdeposited) { ?> <tr> <td><?php echo $paymentdeposited[email];?></td> <td><?php echo $paymentdeposited[amount];?></td> <td><?php echo $paymentdeposited[instrument];?></td> <td><?php echo $paymentdeposited[instrumentnumber];?></td> <td><?php echo $paymentdeposited[dated];?></td> <td><input type="text" name="txtDateDeposited_<?php echo $paymentdeposited[pk_paymentinstrumentid];?>" class="field date-pick"/></td> <td><input type="text" name="txtBankName_<?php echo $paymentdeposited[pk_paymentinstrumentid];?>" class="field"/></td> <td><input type="text" name="txtSlipNo_<?php echo $paymentdeposited[pk_paymentinstrumentid];?>" class="field"/><input type="hidden" name="txtPaymentInstrumentNo_<?php echo $paymentdeposited[pk_paymentinstrumentid];?>" value="<?php echo $paymentdeposited[pk_paymentinstrumentid];?>" class="field"/></td> <td><input type="submit" name="btnSubmit1" value="Submit"/></td> </tr> <?php } ?> </tbody> </table> The print_r command outputs Array ( [txtDateDeposited_57] => 2010-05-07 [txtBankName_57] => pnb [txtSlipNo_57] => 121 [txtPaymentInstrumentNo_57] => 57 [btnSubmit1] => Submit [txtDateDeposited_51] => [txtBankName_51] => [txtSlipNo_51] => [txtPaymentInstrumentNo_51] => 51 [txtDateDeposited_52] => [txtBankName_52] => [txtSlipNo_52] => [txtPaymentInstrumentNo_52] => 52 [txtDateDeposited_45] => [txtBankName_45] => [txtSlipNo_45] => [txtPaymentInstrumentNo_45] => 45 [txtDateDeposited_47] => [txtBankName_47] => [txtSlipNo_47] => [txtPaymentInstrumentNo_47] => 47 ) I want to retrieve the values for id 57 for which he has entered values. But i am unable to construct logic for retrieving this value.I want to make it dynamic. Please help me on this. Thanks

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Best way to get back to using the power of lxml after having to use a regex to find something in an

- by PyNEwbie

I am trying to rip some text out of a large number of html documents (numbers in the hundreds of thousands). The documents are really forms but they are prepared by a very large group of different organizations so there is significant variation in how they create the document. For example, the documents are divided into chapters. I might want to extract the contents of Chapter 5 from every document so I can analyze the content of the chapter. Initially I thought this would be easy but it turns out that the authors might use a set of non-nested tables throughout the document to hold the content so that Chapter n could be displayed using td tags inside a table. Or they might use other elements such as p tags H tags, div tags or any other block level element. After trying repeatedly to use lxml to help me identify the beginning and end of each chapter I have determined that it is a lot cleaner to use a regular expression because in every case, no matter what the enclosing html element is the chapter label is always in the form of >Chapter # It is a little more complicated in that there might be some white space or non-breaking space represented in different ways ( or or just spaces). Nonetheless it was trivial to write a regular expression to identify the beginning of each section. (The beginning of one section is the end of the previous section.) But now I want to use lxml to get the text out. My thought is that I have really no choice but to walk along my string to find the close tag for the element that encloses the text I am using to find the relevant section. That is here is one example where the element holding the Chapter name is a div <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Chapter 1.   Our Beginnings.</font></div> So I am imagining that I would begin at the location where I found the match for chapter 1 and set up a regular expressions to find the next </div|</td|</p|</h1 . . . So at this point I have identified the type of element holding my chapter heading I can use the same logic to find all of the text that is within that element that is set up a regular expression to help me mark from >Chapter 1.   Our Beginnings.< So I have identified where my Chapter 1 begins I can do the same for chapter 2 (which is where Chapter 1 ends) Now I am imagining that I am going to snip the document beginning at the opening of the element that I identified as the element the indicates where chapter 1 begins and ending just before the opening of the element that I identified as the element that indicates where Chapter 2 begins. The string that I have identified will then be fed to lxml to use its power to get the content. I am going to all of this trouble because I have read over and over - never use a regular expression to extract content from html documents and I have not hit on a way to be as accurate with lxml to identify the starting and ending locations for the text I want to extract. For example, I can never be certain that the subtitle of Chapter 1 is Our Beginnings it could be Our Red Canary. Let me say that I spent two solid days trying with lxml to be confident that I had the beginning and ending elements and I could only be accurate <60% of the time but a very short regular expression has given me better than 95% success. I have a tendency to make things more complicated than necessary so I am wondering if anyone has seen or solved a similar problems and if they had an approach (not the details mind you) that they would like to offer.

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Why is my Interface Builder wiring so bonkers and what can I do to straighten it out?

- by editor

I've been working on an iPhone application in XCode and Interface Builder of the Tab Bar project type. After getting a table view of topics (business sectors) working fine I realized that I would need to add a Navigation Control to allow the user to drill into a subtopics (subsectors) table. As a green Objective-C developer, that was confusing, but I managed to get it working by reading various documentation trying out a few different IB options. My current setup is a Tab Bar Controller with Tab 1 as a Navigation Controller and Tab 2 a plain view with a Table View placed into it. The wiring works: I can log when table rows are selected and I'm ready to push a new View Controller onto the stack so that I can display the subtopics Table View. My problem: For some reason the first tab's Table View is a delegate and dataSource of the second ta. It doesn't make sense to me and I can't figure out why that's the only setup that works. Here is the wiring: Navigation Controller (Sectors) is a delegate of Tab Bar Navigation Bar is a delegate of Navigation Controller (Sectors) View Contoller (Sectors) has a view of Table View Table View (in Navigation Controller (Sectors)) is a delegate of First View Controller (Companies) Table View (in Navigation Controller (Sectors)) is a dataSource outlet of First View Controller (Companies) First View Controller (Companies) First View Contoller (Sectors) has a view of Table View Table View (in First View Controller (Companies)) is not hooked up to a dataSource outlet and is not a delegate When I click the tab buttons and look at the Inspector I see that the first tab is correctly hooked up to my MainWindow.xib and the second tab has selected a nib called SecondView.xib. It's in the File's Owner of MainWindow.xib where I inherit UITableViewDataSource and UITableViewDelegate (and also UITabBarControllerDelegate) in the .h, and in the .m where I implement the delegate methods. Why does this setup only work when the Table View in my first tab (View Controller (Sectors)) is a delegate and dataSource of the second tab? I'm confused: why wouldn't it need to be hooked up to the Navigation Controller-enabled tab in which the Table View is seen (Navigation Controller (Sectors))? The Table View seen on the second tab has neither dataSource and is not a delegate. I'm having trouble getting a pushViewController to fire (self.navigationController is not nil but the new View Controller still doesn't load) and I suspect that I need to work out this IB wiring issue before I can troubleshoot why the Nav Controller won't push a new View Controller onto the stack. if(nil == self.navigationController) { NSLog(@"self.navigationController is nil."); } else { NSLog(@"self.navigationController is not nil."); SectorList *subsectorViewController = [[SectorList alloc] initWithNibName:@"SectorList" bundle:nil]; subsectorViewController.title = @"Subsectors"; [[self navigationController] pushViewController:subsectorViewController animated:YES]; [subsectorViewController release]; }

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Update UI from an event with a thread

- by tyrone-tudehope

Im working on a small application to try out an idea that I have. The idea is to periodically update the UI when event of some sort occurs. In the demo I've created, I'm updating a ProgressDialog every 2 seconds for 15 turns. The problem I am having, which I don't quite understand is that when an event is handled, I send a message to the handler which is supposed to update the message in the ProgressDialog. When this happens however, I get an exception which states that I can't update the UI from that thread. The following code appears in my Activity: ProgressDialog diag; String diagMessage = "Started loading..."; final static int MESSAGE_DATA_RECEIVED = 0; final static int MESSAGE_RECEIVE_COMPLETED = 1; final Handler handler = new Handler(){ @Override public void handleMessage(Message msg){ diag.setMessage(diagMessage); switch(msg.what){ case MESSAGE_DATA_RECEIVED: break; case MESSAGE_RECEIVE_COMPLETED: dismissDialog(); killDialog(); break; } } }; Boolean isRunning = false; /** * Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setupDialog(); if(isRunning){ showDialog(); } setContentView(R.layout.main); } void setupDialog(){ if(diag == null){ diag = new ProgressDialog(ThreadLoading.this); diag.setMessage(diagMessage); } } void showDialog(){ isRunning = true; if(diag != null && !diag.isShowing()){ diag.show(); } } void dismissDialog(){ if(diag != null && diag.isShowing()){ diag.dismiss(); } } void killDialog(){ isRunning = false; } public void onStart(){ super.onStart(); showDialog(); Thread background = new Thread(new Runnable(){ public void run(){ try{ final ThreadRunner tr = new ThreadRunner(); tr.setOnDataReceivedListener(new ThreadRunner.OnDataReceivedListener(){ public void onDataReceived(String message){ diagMessage = message; handler.handleMessage(handler.obtainMessage(MESSAGE_DATA_RECEIVED)); } }); tr.setOnDataDownloadCompletedEventListener(new ThreadRunner.OnDataDownloadCompletedListener(){ public void onDataDownloadCompleted(String message){ diagMessage = message; handler.handleMessage(handler.obtainMessage(MESSAGE_RECEIVE_COMPLETED)); } }); tr.runProcess(); } catch(Throwable t){ throw new RuntimeException(t); } } }); background.start(); } @Override public void onPause(){ super.onPause(); dismissDialog(); } For curiosity sake, here's the code for the ThreadRunner class: public interface OnDataReceivedListener { public void onDataReceived(String message); } public interface OnDataDownloadCompletedListener { public void onDataDownloadCompleted(String message); } private OnDataReceivedListener onDataReceivedEventListener; private OnDataDownloadCompletedListener onDataDownloadCompletedEventListener; int maxLoop = 15; int loopCount = 0; int sleepTime = 2000; public void setOnDataReceivedListener(OnDataReceivedListener onDataReceivedListener){ this.onDataReceivedEventListener = onDataReceivedListener; } public void setOnDataDownloadCompletedEventListener(OnDataDownloadCompletedListener onDataDownloadCompletedListener){ this.onDataDownloadCompletedEventListener = onDataDownloadCompletedListener; } public void runProcess(){ for(loopCount = 0; loopCount < maxLoop; loopCount++){ try{ Thread.sleep(sleepTime); onDataReceivedEventListener.onDataReceived(Integer.toString(loopCount)); } catch(Throwable t){ throw new RuntimeException(t); } } onDataDownloadCompletedEventListener.onDataDownloadCompleted("Download is completed"); } Am I missing something? The logic makes sense to me and it looks like everything should work, I'm using a handler to update the UI like it is recommended. Any help will be appreciated. Thanks, Tyrone P.S. I'm developing for Android 1.5

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Repeating fields in similar database tables

- by user1738833

I have been tasked with working on a database that I have never seen before and I'm looking at the DB structure. Some of the central and most heavily queried and joined tables look like virtual duplicates of each other. Here's a massively simplified representation of the situation, with business-sensitive information changed, listing hypothetical table names and fields: TopLevelGroup: PK_TLGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubGroup: PK_SubGroupId, FK_ParentTopLevelGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubSubGroup: PK_SubSUbGroupId, FK_ParentSubGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK I haven't listed the types of the fields as I don't think it's particularly important to the situation. In addition, it's worth saying that rather than four repeated fields as in the example above, I'm looking at 86 repeated fields. For the most part, those fields genuinely do represent "facts" about the primary table entity, so it's not automatically wrong for that reason. In addition, the "groups" represented here have a property inheritance relationship. If DisplaysXOnBill is NULL in the SubSubGroup, it takes the value of DisplaysXOnBillfrom it's parent, the SubGroup, and so-on up to the TopLevelGroup. Further, the requirements will never require that the model extends beyond three levels, so there is no need for flexibility in that area. Is there a design smell from several tables which describe very similar entities having almost identical fields? If so, what might be a better design of the example above? I'm using the phrase "design smell" to indicate a possible problem. Of course, in any given situation, a particular design might well be the best solution. I'm looking for a more general answer - wondering what might be wrong with this design and what might be the better design were that the case. Possibly related, but not primary questions: Is this database schema in a reasonably normal form (e.g. to 3NF), insofar as can be told from the information I've provided. I can't see a problem with the requirements of 2NF and 3NF, except in their inheriting the requirements of 1NF. Is 1NF satisfied though? Are repeating groups allowed in different tables? Is there a best-practice method for implementing the inheritance relationship in a database as I require? The method above feels clunky to me because any query on the SubSubGroup necessarily needs to join onto the SubGroup and the TopLevelGroup tables to collect inherited facts, which can make even trivial joins requiring facts from the SubSubGroup table rather long-winded. There are, of course, political considerations to making a relatively large change like this. For the purpose of this question, I'm happy to ignore that fact in the interests of keeping the answers ring-fenced to the technical problem.

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C - circular character buffer w/ pthreads

- by Matt

I have a homework assignment where I have to implement a circular buffer and add and remove chars with separate threads: #include <pthread.h> #include <stdio.h> #define QSIZE 10 pthread_cond_t full,/* count == QSIZE */ empty,/* count == 0 */ ready; pthread_mutex_t m, n; /* implements critical section */ unsigned int iBuf, /* tail of circular queue */ oBuf; /* head of circular queue */ int count; /* count characters */ char buf [QSIZE]; /* the circular queue */ void Put(char s[]) {/* add "ch"; wait if full */ pthread_mutex_lock(&m); int size = sizeof(s)/sizeof(char); printf("size: %d", size); int i; for(i = 0; i < size; i++) { while (count >= QSIZE) pthread_cond_wait(&full, &m);/* is there empty slot? */ buf[iBuf] = s[i]; /* store the character */ iBuf = (iBuf+1) % QSIZE; /* increment mod QSIZE */ count++; if (count == 1) pthread_cond_signal(&empty);/* new character available */ } pthread_mutex_unlock(&m); } char Get() {/* remove "ch" from queue; wait if empty */ char ch; pthread_mutex_lock(&m); while (count <= 0) pthread_cond_wait(&empty, &m);/* is a character present? */ ch = buf[oBuf]; /* retrieve from the head of the queue */ oBuf = (oBuf+1) % QSIZE; count--; if (count == QSIZE-1) pthread_cond_signal(&full);/* signal existence of a slot */ pthread_mutex_unlock(&m); return ch; } void * p1(void *arg) { int i; for (i = 0; i < 5; i++) { Put("hella"); } } void * p2(void *arg) { int i; for (i = 0; i < 5; i++) { Put("goodby"); } } int main() { pthread_t t1, t2; void *r1, *r2; oBuf = 0; iBuf = 0; count=0; /* all slots are empty */ pthread_cond_init(&full, NULL); pthread_cond_init(&empty, NULL); pthread_mutex_init(&m, NULL); pthread_create(&t1, NULL, p1, &r1); pthread_create(&t2, NULL, p2, &r2); printf("Main"); char c; int i = 0; while (i < 55) { c = Get(); printf("%c",c); i++; } pthread_join(t1, &r1); pthread_join(t2, &r2); return 0; } I shouldn't have to change the logic much at all, the requirements are pretty specific. I think my problem lies in the Put() method. I think the first thread is going in and blocking the critical section and causing a deadlock. I was thinking I should make a scheduling attribute? Of course I could be wrong. I am pretty new to pthreads and concurrent programming, so I could really use some help spotting my error.

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Design Technique: How to design a complex system for processing orders, products and units.

- by Shyam

Hi, Programming is fun: I learned that by trying out simple challenges, reading up some books and following some tutorials. I am able to grasp the concepts of writing with OO (I do so in Ruby), and write a bit of code myself. What bugs me though is that I feel re-inventing the wheel: I haven't followed an education or found a book (a free one that is) that explains me the why's instead of the how's, and I've learned from the A-team that it is the plan that makes it come together. So, armed with my nuby Ruby skills, I decided I wanted to program a virtual store. I figured out the following: My virtual Store will have: Products and Services Inventories Orders and Shipping Customers Now this isn't complex at all. With the help of some cool tools (CMapTools), I drew out some concepts, but quickly enough (thanks to my inferior experience in designing), my design started to bite me. My very first product-line were virtual "laptops". So, I created a class (Ruby): class Product attr_accessor :name, :price def initialize(name, price) @name = name @price = price end end which can be instantiated by doing (IRb) x = Product.new("Banana Pro", 250) Since I want my virtual customers to be able to purchase more than one product, or various types, I figured out I needed some kind of "Order" mechanism. class Order def initialize(order_no) @order_no = order_no @line_items = [] end def add_product(myproduct) @line_items << myproduct end def show_order() puts @order_no @line_items.each do |x| puts x.name.to_s + "\t" + x.price.to_s end end end that can be instantiated by doing (IRb) z = Order.new(1234) z.add_product(x) z.show_order Splendid, I have now a very simple ordering system that allows me to add products to an order. But, here comes my real question. What if I have three models of my product (economy, business, showoff)? Or have my products be composed out of separate units (bigger screen, nicer keyboard, different OS)? Surely I could make them three separate products, or add complexity to my product class, but I am looking for are best practices to design a flexible product object that can be used in the real world, to facilitate a complex system. My apologies if my grammar and my spelling are with error, as english is not my first language and I took the time to check as far I could understand and translate properly! Thank you for your answers, comments and feedback!

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Issue getting camera emulation to work with Tom G's HttpCamera

- by user591524

I am trying to use the android emulator to preview video from webcam. I have used the tom gibara sample code, minus the webbroadcaster (i am instead using VLC streaming via http). So, I have modified the SDK's "CameraPreview" app to use the HttpCamera, but the stream never appears. Debugging through doesn't give me any clues either. I wonder if anything obvious is clear to others? The preview app launches and remains black. Notes: 1) I have updated the original CameraPreview class as described here: http://www.inter-fuser.com/2009/09/live-camera-preview-in-android-emulator.html, but referencing httpCamera instead of socketcamera. 2) I updated Tom's original example to reference "Camera" type instead of deprecated "CameraDevice" type. 3) Below is my CameraPreview.java. 4) THANK YOU package com.example.android.apis.graphics; import android.app.Activity; import android.content.Context; import android.hardware.Camera; import android.os.Bundle; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.Window; import java.io.IOException; import android.graphics.Canvas; // ---------------------------------------------------------------------- public class CameraPreview extends Activity { private Preview mPreview; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Hide the window title. requestWindowFeature(Window.FEATURE_NO_TITLE); // Create our Preview view and set it as the content of our activity. mPreview = new Preview(this); setContentView(mPreview); } } // ---------------------------------------------------------------------- class Preview extends SurfaceView implements SurfaceHolder.Callback { SurfaceHolder mHolder; //Camera mCamera; HttpCamera mCamera;//changed Preview(Context context) { super(context); // Install a SurfaceHolder.Callback so we get notified when the // underlying surface is created and destroyed. mHolder = getHolder(); mHolder.addCallback(this); //mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); mHolder.setType(SurfaceHolder.SURFACE_TYPE_NORMAL);//changed } public void surfaceCreated(SurfaceHolder holder) { // The Surface has been created, acquire the camera and tell it where // to draw. //mCamera = Camera.open(); this.StartCameraPreview(holder); } public void surfaceDestroyed(SurfaceHolder holder) { // Surface will be destroyed when we return, so stop the preview. // Because the CameraDevice object is not a shared resource, it's very // important to release it when the activity is paused. //mCamera.stopPreview();//changed mCamera = null; } public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { // Now that the size is known, set up the camera parameters and begin // the preview. //Camera.Parameters parameters = mCamera.getParameters(); //parameters.setPreviewSize(w, h); //mCamera.setParameters(parameters); //mCamera.startPreview(); this.StartCameraPreview(holder); } private void StartCameraPreview(SurfaceHolder sh) { mCamera = new HttpCamera("10.213.74.247:443", 640, 480, true);//changed try { //mCamera.setPreviewDisplay(holder); Canvas c = sh.lockCanvas(null); mCamera.capture(c); sh.unlockCanvasAndPost(c); } catch (Exception exception) { //mCamera.release(); mCamera = null; // TODO: add more exception handling logic here } } }

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PHP: Condense array of similar strings into one merged array

- by Matt Andrews

Hi everyone. Working with an array of dates (opening times for a business). I want to condense them to their briefest possible form. So far, I started out with this structure Array ( [Mon] => 12noon-2:45pm, 5:30pm-10:30pm [Tue] => 12noon-2:45pm, 5:30pm-10:30pm [Wed] => 12noon-2:45pm, 5:30pm-10:30pm [Thu] => 12noon-2:45pm, 5:30pm-10:30pm [Fri] => 12noon-2:45pm, 5:30pm-10:30pm [Sat] => 12noon-11pm [Sun] => 12noon-9:30pm ) What I want to achieve is this: Array ( [Mon-Fri] => 12noon-2:45pm, 5:30pm-10:30pm [Sat] => 12noon-11pm [Sun] => 12noon-9:30pm ) I've tried writing a recursive function and have managed to output this so far: Array ( [Mon-Fri] => 12noon-2:45pm, 5:30pm-10:30pm [Tue-Fri] => 12noon-2:45pm, 5:30pm-10:30pm [Wed-Fri] => 12noon-2:45pm, 5:30pm-10:30pm [Thu-Fri] => 12noon-2:45pm, 5:30pm-10:30pm [Sat] => 12noon-11pm [Sun] => 12noon-9:30pm ) Can anybody see a simple way of comparing the values and combining the keys where they're similar? My recursive function is basically two nested foreach() loops - not very elegant. Thanks, Matt EDIT: Here's my code so far, which produces the 3rd array above (from the first one as input): $last_time = array('t' => '', 'd' => ''); // blank array for looping $i = 0; foreach($final_times as $day=>$time) { if($last_time['t'] != $time ) { // it's a new time if($i != 0) { $print_times[] = $day . ' ' . $time; } // only print if it's not the first, otherwise we get two mondays } else { // this day has the same time as last time $end_day = $day; foreach($final_times as $day2=>$time2) { if($time == $time2) { $end_day = $day2; } } $print_times[] = $last_time['d'] . '-' . $end_day . ' ' . $time; } $last_time = array('t' => $time, 'd' => $day); $i++; }

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CQRS - Should a Command try to create a "complex" master-detail entity?

- by Simon Crabtree

I've been reading Greg Young and Udi Dahan's thoughts on Command Query Responsibilty Separation and a lot of what I read strikes a chord with me. My domain (we track vehicles which are doing deliveries) has the concept of a Route which contains one or more Stops. I need my customers to be able to set these up in our system by calling a webservice, and then be able to retrieve information about a Route and how the vehicle is progressing. In the past I would have "cut-down" DTO classes which closely resemble my domain classes, and the customer would create a RouteDto with an array of StopDto(s), and call our CreateRoute webmethod, passing in the RouteDto. When they query our system by calling the GetRouteDetails method, I would return exactly the same objects to them. One of the appealing aspects of CQRS is that the RouteDto might have all manner of properties that the customer wants to query, but have no business setting when they create a Route. So I create a separate CreateRouteRequest class which is passed in when calling the CreateRoute "command", and a Route DTO class which gets returned as a query result. class Route{ string Reference; List<Stop> Stops; } But I need my customer to provide me with Route AND Stop details when they create a route. As I see it I could either... Give my CreateRouteRequest class a Stops(s) property which is an array of "something" representing the data they need to provide about each stop - but what do I call this class? It's not a Stop as that's what I'm calling the list of DTO inside my Route DTO, but I don't like "CreateStopRequest". I also wonder if I'm stuck in a CRUD mindset here thinking in terms of master-detail information and asking the customer to think like that too. class CreateRouteRequest{ string Reference; ... List<CreateStopRequest> Stops; } or They call CreateRoute, and then make a number of calls to an AddStopToRoute method. This feels a bit more "behavioural" but I'm going to lose the ability to treat creating a route including its stops as a single atomic command. If they create a Route and then try to add a Stop which fails due to some validation problem they're going to have a partially correct Route. The fact that I can't come up with a good name for the list of "StopCreationData" objects I'd be working with in option 1, makes me wonder if there's something I'm missing.

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Array within Form collecting multiple values with the same name possible?

- by JM4

Good afternoon, I will first start with the goal I am trying to accomplish and then give a very basic sample of what I need to do. Goal Instead of collecting several variables and naming them with keys individually, I have decided to give in and use an array structure to handle all inputs of the same type and rules. Once I have the variables, I will validate against them and if 'ok' store them in a MySQL table. The table will hold consumer information and will need to store multiple rows of the same type of information. First Pass I will leave out the validation portion of this question because I feel I need to first understand the basics. <form action="?" method="POST" name="Form"> Member 1 First Name:<input type="text" name="MemberFirstName[]" /><br /> Member 1 Last Name: <input type="text" name="MemberLastName[]" /><br /> Member 1 Email: <input type="text" name="MemberEmail[]" /><br /> Member 2 First Name:<input type="text" name="MemberFirstName[]" /><br /> Member 2 Last Name: <input type="text" name="MemberLastName[]" /><br /> Member 2 Email: <input type="text" name="MemberEmail[]" /><br /> Member 3 First Name:<input type="text" name="MemberFirstName[]" /><br /> Member 3 Last Name: <input type="text" name="MemberLastName[]" /><br /> Member 3 Email: <input type="text" name="MemberEmail[]" /><br /> <input type="submit" name="submit" value="Continue" /> </form> I am hoping that each input given for First Name (a required field) will generate a unique key for that particular entry and not overwrite any data entered. Because I am carrying information from page to page (checkout form), I am turning the POST variables into SESSION variables then storing in a mysql database in the end. My hope is to have: <?php $conn = mysql_connect("localhost", "username", "password"); mysql_select_db("DBname",$conn); $sql = "INSERT INTO tablename VALUES ('$_SESSION[Member1FirstName]', '$_SESSION[Member1LastName]', '$_SESSION[Member1Email]', '$_SESSION[Member2FirstName]', '$_SESSION[Member2LastName]', '$_SESSION[Member2Email]', '$_SESSION[Member1FirstName]', '$_SESSION[Member3LastName]', '$_SESSION[Member3Email]')"; $result = mysql_query($sql, $conn) or die(mysql_error()); Header ("Location: completed.php"); ?> Where Member1, Member2, and Member3 values will appear on their own row within the table. I KNOW my code is wrong but I am giving a first shot at the overall business purpose I am trying to achieve and trying to learn how to code the right way. I am very, very new to programming so any 'baby advice' is greatly appreciated.

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Different setter behavior between DbContext and ObjectContext

- by Paul

(This is using EntityFramework 4.2 CTP) I haven't found any references to this on the web yet, although it's likely I'm using the wrong terminology while searching. There's also a very likely scenario where this is 100% expected behavior, just looking for confirmation and would rather not dig through the tt template (still new to this). Assuming I have a class with a boolean field called Active and I have one row that already has this value set to true. I have code that executes to set said field to True regardless of it's existing value. If I use DbContext to update the value to True no update is made. If I use ObjectContext to update the value an update is made regardless of the existing value. This is happening in the exact same EDMX, all I did was change the code generation template from DbContext to EntityObject. Update: Ok, found the confirmation I was looking for...consider this a dupe...next time I'll do MOAR SEARCHING! Entity Framework: Cancel a property change if no change in value ** Update 2: ** Problem: the default tt template wraps the "if (this != value)" in the setter with "if (iskey), so only primarykey fields receive this logic. Solution: it's not the most graceful thing, but I removed this check...we'll see how it pans out in real usage. I included the entire tt template, my changes are denoted with "**"... //////// //////// Write SimpleType Properties. //////// private void WriteSimpleTypeProperty(EdmProperty simpleProperty, CodeGenerationTools code) { MetadataTools ef = new MetadataTools(this); #> /// <summary> /// <#=SummaryComment(simpleProperty)#> /// </summary><#=LongDescriptionCommentElement(simpleProperty, 1)#> [EdmScalarPropertyAttribute(EntityKeyProperty= <#=code.CreateLiteral(ef.IsKey(simpleProperty))#>, IsNullable=<#=code.CreateLiteral(ef.IsNullable(simpleProperty))#>)] [DataMemberAttribute()] <#=code.SpaceAfter(NewModifier(simpleProperty))#><#=Accessibility.ForProperty(simpleProperty)#> <#=MultiSchemaEscape(simpleProperty.TypeUsage, code)#> <#=code.Escape(simpleProperty)#> { <#=code.SpaceAfter(Accessibility.ForGetter(simpleProperty))#>get { <#+ if (ef.ClrType(simpleProperty.TypeUsage) == typeof(byte[])) { #> return StructuralObject.GetValidValue(<#=code.FieldName(simpleProperty)#>); <#+ } else { #> return <#=code.FieldName(simpleProperty)#>; <#+ } #> } <#=code.SpaceAfter(Accessibility.ForSetter((simpleProperty)))#>set { <#+ **//if (ef.IsKey(simpleProperty)) **//{ if (ef.ClrType(simpleProperty.TypeUsage) == typeof(byte[])) { #> if (!StructuralObject.BinaryEquals(<#=code.FieldName(simpleProperty)#>, value)) <#+ } else { #> if (<#=code.FieldName(simpleProperty)#> != value) <#+ } #> { <#+ PushIndent(CodeRegion.GetIndent(1)); **//} #> <#=ChangingMethodName(simpleProperty)#>(value); ReportPropertyChanging("<#=simpleProperty.Name#>"); <#=code.FieldName(simpleProperty)#> = <#=CastToEnumType(simpleProperty.TypeUsage, code)#>StructuralObject.SetValidValue(<#=CastToUnderlyingType(simpleProperty.TypeUsage, code)#>value<#=OptionalNullableParameterForSetValidValue(simpleProperty, code)#>, "<#=simpleProperty.Name#>"); ReportPropertyChanged("<#=simpleProperty.Name#>"); <#=ChangedMethodName(simpleProperty)#>(); <#+ //if (ef.IsKey(simpleProperty)) //{ PopIndent(); #> } <#+ //} #> } }

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When Clearing an ObservableCollection, There are No Items in e.OldItems

- by cplotts

I have something here that is really catching me off guard. I have an ObservableCollection of T that is filled with items. I also have an event handler attached to the CollectionChanged event. When you Clear the collection it causes an CollectionChanged event with e.Action set to NotifyCollectionChangedAction.Reset. Ok, that's normal. But what is weird is that neither e.OldItems or e.NewItems has anything in it. I would expect e.OldItems to be filled with all items that were removed from the collection. Has anyone else seen this? And if so, how have they gotten around it? Some background: I am using the CollectionChanged event to attach and detach from another event and thus if I don't get any items in e.OldItems ... I won't be able to detach from that event. CLARIFICATION: I do know that the documentation doesn't outright state that it has to behave this way. But for every other action, it is notifying me of what it has done. So, my assumption is that it would tell me ... in the case of Clear/Reset as well. Below is the sample code if you wish to reproduce it yourself. First off the xaml: <Window x:Class="ObservableCollection.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Window1" Height="300" Width="300" > <StackPanel> <Button x:Name="addButton" Content="Add" Width="100" Height="25" Margin="10" Click="addButton_Click"/> <Button x:Name="moveButton" Content="Move" Width="100" Height="25" Margin="10" Click="moveButton_Click"/> <Button x:Name="removeButton" Content="Remove" Width="100" Height="25" Margin="10" Click="removeButton_Click"/> <Button x:Name="replaceButton" Content="Replace" Width="100" Height="25" Margin="10" Click="replaceButton_Click"/> <Button x:Name="resetButton" Content="Reset" Width="100" Height="25" Margin="10" Click="resetButton_Click"/> </StackPanel> </Window> Next, the code behind: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; using System.Collections.ObjectModel; namespace ObservableCollection { /// <summary> /// Interaction logic for Window1.xaml /// </summary> public partial class Window1 : Window { public Window1() { InitializeComponent(); _integerObservableCollection.CollectionChanged += new System.Collections.Specialized.NotifyCollectionChangedEventHandler(_integerObservableCollection_CollectionChanged); } private void _integerObservableCollection_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) { switch (e.Action) { case System.Collections.Specialized.NotifyCollectionChangedAction.Add: break; case System.Collections.Specialized.NotifyCollectionChangedAction.Move: break; case System.Collections.Specialized.NotifyCollectionChangedAction.Remove: break; case System.Collections.Specialized.NotifyCollectionChangedAction.Replace: break; case System.Collections.Specialized.NotifyCollectionChangedAction.Reset: break; default: break; } } private void addButton_Click(object sender, RoutedEventArgs e) { _integerObservableCollection.Add(25); } private void moveButton_Click(object sender, RoutedEventArgs e) { _integerObservableCollection.Move(0, 19); } private void removeButton_Click(object sender, RoutedEventArgs e) { _integerObservableCollection.RemoveAt(0); } private void replaceButton_Click(object sender, RoutedEventArgs e) { _integerObservableCollection[0] = 50; } private void resetButton_Click(object sender, RoutedEventArgs e) { _integerObservableCollection.Clear(); } private ObservableCollection<int> _integerObservableCollection = new ObservableCollection<int> { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 }; } }

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