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  • Dependency Property ListBox

    - by developer
    Hi All, I want to use a dependency property, so that my label displays values selected in the listbox. This is just to more clearly understand the working of a dependency property. <Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:WPFToolkit="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit" xmlns:local="clr-namespace:WpfApplication1" x:Name="MyWindow" Height="200" Width="300" > <StackPanel> <ListBox x:Name="lbColor" Width="248" Height="56" ItemsSource="{Binding TestColor}"/> <StackPanel> <Label Content="{Binding Path=Test, ElementName=lbColor}" /> </StackPanel> </StackPanel> </Window> Code Behind, namespace WpfApplication1 { /// <summary> /// Interaction logic for Window1.xaml /// </summary> public partial class Window1 : Window { public ObservableCollection<string> TestColor { get; set; } public String Test { get { return (String)GetValue(TestProperty); } set { SetValue(TestProperty, value); } } // Using a DependencyProperty as the backing store for Title. This enables animation, styling, binding, etc... public static readonly DependencyProperty TestProperty = DependencyProperty.Register("Test", typeof(String), typeof(ListBox), new UIPropertyMetadata("Test1")); public Window1() { InitializeComponent(); TestColor = new ObservableCollection<string>(); DataContext = this; TestColor.Add("Red"); TestColor.Add("Orange"); TestColor.Add("Yellow"); TestColor.Add("Green"); TestColor.Add("Blue"); } } } Can anyone explain me how will I accompalish this using a dependency property. Somehow I am very confused with the Dependency Property concept, and I just wanted to see a working example for that.

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  • PHP, MySQL: mysql substitute for php in_array function

    - by Devner
    Hi all, Say if I have an array and I want to check if an element is a part of that array, I can go ahead and use in_array( needle, haystack ) to determine the results. I am trying to see the PHP equivalent of this for my purpose. Now you might have an instant answer for me and you might be tempted to say "Use IN". Yes, I can use IN, but that's not fetching the desired results. Let me explain with an example: I have a column called "pets" in DB table. For a record, it has a value: Cat, dog, Camel (Yes, the column data is a comma separated value). Consider that this row has an id of 1. Now I have a form where I can enter the value in the form input and use that value check against the value in the DB. So say I enter the following comma separated value in the form input: CAT, camel (yes, CAT is uppercase & intentional as some users tend to enter it that way). Now when I enter the above info in the form input and submit, I can collect the POST'ed info and use the following query: $search = $_POST['pets']; $sql = "SELECT id FROM table WHERE pets IN ('$search') "; The above query is not fetching me the row that already exists in the DB (remember the record which has Cat, dog, Camel as the value for the pets column?). I am trying to get the records to act as a superset and the values from the form input as subsets. So in this case I am expecting the id value to show up as the values exist in the column, but this is not happending. Now say if I enter just CAT as the form input and perform the search, it should show me the ID 1 row. Now say if I enter just camel, cAT as the form input and perform the search, it should show me the ID 1 row. How can I achieve the above? Thank you.

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  • How to use void*

    - by Rondogiannis Aristophanes
    I am imlementing a simple merge function and I have got stuck, as the compiler gives me errors that I cannot explain. Here is my merge function: void merge(void *a, int beg, int middle, int end, int (*cmp)(const void*, const void* { std::stack<void*> first; std::stack<void*> second; for(int i = beg; i < middle; i++) { first.push(a+i); } for(int i = middle; i < end; i++) { second.push(a+i); } for(int i = beg; i < end; i++) { if(first.empty()) { void *tmp = second.top(); second.pop(); a+i = tmp; } else if(second.empty()) { void *tmp = first.top(); first.pop(); a+i = tmp; } else if(cmp(first.top(), second.top())) { void *tmp = first.top(); first.pop(); a+i = tmp; } else { void *tmp = second.top(); second.pop(); a+i = tmp; } } } And here is the error: sort.h: In function `void merge(void*, int, int, int, int (*)(const void*, const void*))': sort.h:9: error: pointer of type `void *' used in arithmetic sort.h:12: error: pointer of type `void *' used in arithmetic sort.h:19: error: pointer of type `void *' used in arithmetic sort.h:19: error: non-lvalue in assignment sort.h:23: error: pointer of type `void *' used in arithmetic sort.h:23: error: non-lvalue in assignment sort.h:27: error: pointer of type `void *' used in arithmetic sort.h:27: error: non-lvalue in assignment sort.h:31: error: pointer of type `void *' used in arithmetic sort.h:31: error: non-lvalue in assignment Can anyone help me? TIA.

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  • Please help optimizing a long running query (left outer join, with 2 subqueries)

    - by 46and2
    Hi all. The query I need help with is: SELECT d.bn, d.4700, d.4500, ... , p.`Activity Description` FROM ( SELECT temp.bn, temp.4700, temp.4500, .... FROM `tdata` temp GROUP BY temp.bn HAVING (COUNT(temp.bn) = 1) ) d LEFT OUTER JOIN ( SELECT temp2.bn, max(temp2.FPE) AS max_fpe, temp2.`Activity Description` FROM `pdata` temp2 GROUP BY temp2.bn ) p ON p.bn = d.bn; The ... represents other fields that aren't really important to solving this problem. The issue is on the the second subquery - it is not using the index I have created and I am not sure why, it seems to be because of the way TEXT fields are handled. The first subquery uses the index I have created and runs quite snappy, however an explain on the second shows a 'Using temporary; Using filesort'. Please see the indexes I have created in the below table create statements. Can anyone help me optimize this? By way of quick explanation the first subquery is meant to only select records that have unique bn's, the second, while it looks a bit wacky (with the max function there which is not being used in the result set) is making sure that only one record from the right part of the join is included in the result set. My table create statements are CREATE TABLE `tdata` ( `BN` varchar(15) DEFAULT NULL, `4000` varchar(3) DEFAULT NULL, `5800` varchar(3) DEFAULT NULL, .... KEY `BN` (`BN`), KEY `idx_t3010`(`BN`,`4700`,`4500`,`4510`,`4520`,`4530`,`4570`,`4950`,`5000`,`5010`,`5020`,`5050`,`5060`,`5070`,`5100`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 CREATE TABLE `pdata` ( `BN` varchar(15) DEFAULT NULL, `FPE` datetime DEFAULT NULL, `Activity Description` text, .... KEY `BN` (`BN`), KEY `idx_programs_2009` (`BN`,`FPE`,`Activity Description`(100)) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 Thanks!

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  • java annotations - problem with calling a locator class from a Vaadin Project

    - by George
    Hello, I'm not sure how to explain this without writing several pages so I hope the actual code is more expressive. I've made a jar containing multiple annotation declaration similar to the following: @Target(ElementType.PACKAGE) @Retention(RetentionPolicy.RUNTIME) public @interface MarkedPackage { } then I have made a test jar containing several classes in several packages and marked just one package with the above annotation (with package-info.java) like below: @myPackage.MarkedPackage package package.test.jar; this jar had in its build path the jar containing the annotations. then I made a static class that has a method (LoadPlugins) that retrieves a list with all the jars of a directory. Then it searches through the jars for the 'package-info' class and checks if that classes package contains the MarkedPackage annotation. by calling this: if (checkPackageAnnotation(thisClass.getPackage())) where thisClass is the package-info class retrieved via a classloader. and: public static boolean checkPackageAnnotation(AnnotatedElement elem) { System.out.println(elem.getAnnotations().length); if (elem == null || !elem.isAnnotationPresent(MarkedPackage.class)) return false; return true; } the elem.getAnnotatios().length is there for debug purposes. And the problem appears when I call the method from the static class: if I call it from a main function: public class MyMain { public static void main(String[] args){ PluginUtils.LoadPlugins(); } } everything works perfectly it displays '1' from that System.out.println(elem.getAnnotations().length); But if I call it from a button from my Vaadin project: header.addComponent(new Button("CallThat", new Button.ClickListener() { public void buttonClick(ClickEvent event) { PluginUtils.LoadPlugins(); } })); It displays '0' from that System.out.println(elem.getAnnotations().length); Also I should mention that I created the main inside my Vaadin project so it would have the exact same build path and resources. Is there a problem with web applications and that "@Retention(RetentionPolicy.RUNTIME)" ? hope I was clear enough... Hope someone has a solution for me... If you need more information - let me know. Thank you.

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  • Object Oriented Programming in AS3

    - by Jordan
    I'm building a game in as3 that has balls moving and bouncing off the walls. When the user clicks an explosion appears and any ball that hits that explosion explodes too. Any ball that then hits that explosion explodes and so on. My question is what would be the best class structure for the balls. I have a level system to control levels and such and I've already come up with working ways to code the balls. Here's what I've done. My first attempt was to create a class for Movement, Bounce, Explosion and finally Orb. These all extended each other in the order I just named them. I got it working but having Bounce extend Movement and Explosion extend Bounce, it just doesn't seem very object oriented because what if I wanted to add a box class that didn't move, but did explode? I would need a separate class for that explosion. My second attempt was to create Movement, Bounce and Explosion without extending anything. Instead I passed in a reference to the Orb class to each. Then the class stores that reference and does what it needs to do based on events that are dispatched by the Orb such as update, which was broadcast from Orb every enter frame. This would drive the movement and bounce and also the explosion when the time came. This attempt worked as well but it just doesn't seem right. I've also thought about using Interfaces but because they are more of an outline for classes, I feel like code reuse goes out the window as each class would need its own code for a specific task even if that task is exactly the same. I feel as if I'm searching for some form of multiple inheritance for classes that as3 does not support. Can someone explain to me a better way of doing what I'm attempting to do? Am I being to "Object Oriented" by having classed for Movement, Bounce, Explosion and Orb? Are Interfaces the way to go? Any feedback is appreciated!

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  • Why does this data YYYY-MM-DD regex fail in Java?

    - by ProfessionalAmateur
    Hello StackOverFlow, My first question and Im excited... I've lurked since go-live and love the site, however I apologize for any newbie errors, formatting, etc... I'm attempting to validate the format of a string field that contains a date in Java. We will receive the date in a string, I will validate its format before parsing it into a real Date object. The format being passed in is in the YYYY-MM-DD format. However I'm stuck on one of my tests, if I pass in "1999-12-33" the test will fail (as it should with a day number 33) with this incomplete pattern: ((19|20)\\d{2})-([1-9]|0[1-9]|1[0-2])-([12][0-9]|3[01]) However as soon as I add the characters in bold below it passes the test (but should not) ((19|20)\\d{2})-([1-9]|0[1-9]|1[0-2])-(0[1-9]|[1-9]|[12][0-9]|3[01]) *additional note, I know I can change the 0[1-9]|[1-9] into 0?[1-9] but I wanted to break everything down to its most simple format to try and find why this isn't working. Here is the scrap test I've put together to run through all the different date scenarios: import java.util.regex.Matcher; import java.util.regex.Pattern; public class scrapTest { public scrapTest() { } public static void main(String[] args) { scrapTest a = new scrapTest(); boolean flag = a.verfiyDateFormat("1999-12-33"); } private boolean verfiyDateFormat(String dateStr){ Pattern datePattern = Pattern.compile("((19|20)\\d{2})-([1-9]|0[1-9]|1[0-2])-(0[1-9]|[1-9]|[12][0-9]|3[01])"); Matcher dateMatcher = datePattern.matcher(dateStr); if(!dateMatcher.find()){ System.out.println("Invalid date format!!! -> " + dateStr); return false; } System.out.println("Valid date format."); return true; } } Ive been programming for ~10 years but extremely new to Java, so please feel free to explain anything as elementary as you see fit.

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  • Practical refactoring using unit tests

    - by awhite
    Having just read the first four chapters of Refactoring: Improving the Design of Existing Code, I embarked on my first refactoring and almost immediately came to a roadblock. It stems from the requirement that before you begin refactoring, you should put unit tests around the legacy code. That allows you to be sure your refactoring didn't change what the original code did (only how it did it). So my first question is this: how do I unit-test a method in legacy code? How can I put a unit test around a 500 line (if I'm lucky) method that doesn't do just one task? It seems to me that I would have to refactor my legacy code just to make it unit-testable. Does anyone have any experience refactoring using unit tests? And, if so, do you have any practical examples you can share with me? My second question is somewhat hard to explain. Here's an example: I want to refactor a legacy method that populates an object from a database record. Wouldn't I have to write a unit test that compares an object retrieved using the old method, with an object retrieved using my refactored method? Otherwise, how would I know that my refactored method produces the same results as the old method? If that is true, then how long do I leave the old deprecated method in the source code? Do I just whack it after I test a few different records? Or, do I need to keep it around for a while in case I encounter a bug in my refactored code? Lastly, since a couple people have asked...the legacy code was originally written in VB6 and then ported to VB.NET with minimal architecture changes.

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  • Is MVVM killing silverlight development?

    - by DeanMc
    This is a question I have had rattling around in my head for some time. I had a chat with a guy the other night who told me he would not be using the navigational framework because he could not figure out how it works with MVVM. As much as I tried to explain that patterns should be taken with a pinch of salt he would not listen. My point is this, patterns are great when they solve some problem. Sometimes only part of the pattern solves a particular problem while the other parts of it cause different problems. The goal of any developer is to build a solid application using a combination of patterns know how and foresight. I feel MVVM is becoming the one pattern to rule them all. As it is not directly supported by .Net some fancy business is needed to make it work. I feel that people are missing the point of the pattern, which is loosely coupled, testable code and instead jumping through hoops and missing out on great experiences trying to follow MVVM to the letter. MVVM is great but I wish it came with a warning or disclaimer for newbies as my fear is people will shy away from silverlight development for fear of being smacked with the mvvm stick. EDIT: Can I just add as an edit, I use and agree with MVVM as a pattern I know when it is and isn't feasible in my projects. My issue is with the encompassing nature it is taking, as if it HAS to be used as part of development. It is being used as an integral feature and not a pattern, which it is.

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  • Why qry.post executed with asynchronous mode?

    - by Ryan
    Recently I met a strange problem, see code snips as below: var sqlCommand: string; connection: TADOConnection; qry: TADOQuery; begin connection := TADOConnection.Create(nil); try connection.ConnectionString := 'Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Test.MDB;Persist Security Info=False'; connection.Open(); qry := TADOQuery.Create(nil); try qry.Connection := connection; qry.SQL.Text := 'Select * from aaa'; qry.Open; qry.Append; qry.FieldByName('TestField1').AsString := 'test'; qry.Post; beep; finally qry.Free; end; finally connection.Free; end; end; First, Create a new access database named test.mdb and put it under the directory of this test project, we can create a new table named aaa in it which has only one text type field named TestField1. We set a breakpoint at line of "beep", then lunch the test application under ide debug mode, when ide stops at the breakpoint line (qry.post has been executed), at this time we use microsoft access to open test.mdb and open table aaa you will find there are no any changes in table aaa, if you let the ide continue running after pressing f9 you can find a new record is inserted in to table aaa, but if you press ctrl+f2 to terminate the application at the breakpoint, you will find the table aaa has no record been inserted, but in normal circumstance, a new record should be inserted in to the table aaa after qry.post executed. who can explain this problem , it troubles me so long time. thanks !!! BTW, the ide is delphi 2010, and the access mdb file is created by microsoft access 2007 under windows 7

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  • Reading a Wordpress function description

    - by Casebash
    I want to be able to understand the standard function description that is provided for Wordpress functions. In particular, could someone explain the following example from here: Usage <?php wp_list_categories( $args ); ?> Default Usage <?php $args = array( 'show_option_all' => , 'orderby' => 'name', 'order' => 'ASC', 'show_last_update' => 0, 'style' => 'list', 'show_count' => 0, 'hide_empty' => 1, 'use_desc_for_title' => 1, 'child_of' => 0, 'feed' => , 'feed_type' => , 'feed_image' => , 'exclude' => , 'exclude_tree' => , 'include' => , 'current_category' => 0, 'hierarchical' => true, 'title_li' => __( 'Categories' ), 'number' => NULL, 'echo' => 1, 'depth' => 0 ); ?> I can guess most of it, but in particular I can't guess: What does blank after the comma mean? Empty string? What is the __? How do I call the function? Keyword like python, positional arguments or do I have to pass an array? Is there anything else about Wordpress function descriptions which isn't covered in this example? Thanks, Chris

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  • is it possible to write a method which creates a method?

    - by Alan Bennett
    hey guys, this might seem like a no brainer but hopefully after i explain my problem you might understand why i am asking this. is it possible to have a method which creates a method and its arguements? the problem: in my current project i have to many times call different sql statements which arent all that different. for example i have one where i inserts some new rows but only has 2 columns and another which also inserts new rows but has 12 columns. i have created a class called utils.cs and in there i have sorted many "handy" methods, such as validation methods which check for numeric input to text boxes etc. so i thought well instead of having sql writing methods everywhere ill make one in there and call it when i need to so i have but it currently looks like this: public static string getInsertSQL(string tablename, string colOne, string colTwo, string colThree, string colFour, string colFive, string colSix, string colSeven, string colEight, string colNine, string colTen, string colEleven, string colTwelve,bool active, string valueOne, string valueTwo, string valueThree, string valueFour, string valueFive, string valueSix, string valueSeven, string valueEight, string valueNine, string valueTen, string valueEleven) { string strSQL = ""; strSQL += "INSERT INTO " + tablename; strSQL += "(" + colOne + " " + colTwo + " " + colThree + " " + colFour + " " + colFive + " " + colSix + " " + colSeven + " " + colEight + " " + colNine + " " + colTen + " " + colEleven + " " + colTwelve + " )"; strSQL += " values ("+active+", " + valueOne + " " + valueTwo + " " + valueThree + " " + valueFour + " " + valueFive + " " + valueSix + " " + valueSeven + " " + valueEight + " " + valueNine + " " + valueTen + " " + valueEleven + " )"; return strSQL; } as you can see thats quite a mess so i wondered if it was at all possible to write a method which would take an arguement of how many colums needed to be inserted and then could create a method with that many arguements. i hope you can see what i am getting at and dont just sound like a plep! thanks in advance

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  • Why Can I Change Struct's int[] Property from Method Without Specifying "ref"?

    - by AMissico
    From a method, I can pass a struct which contains an array of integers, and change the values in the array. I am not sure I understand fully why I can do this. Can someone please explain why I can change the values stored in the int[]? private void DoIt(){ SearchInfo a = new SearchInfo(); a.Index = 1; a.Map = new int[] { 1 }; SearchInfo b = new SearchInfo(); b.Index = 1; b.Map = new int[] { 1 }; ModifyA(a); ModifyB(ref b); Debug.Assert(a.Index == 1); Debug.Assert(a.Map[0] == 1, "why did this change?"); Debug.Assert(b.Index == 99); Debug.Assert(b.Map[0] == 99); } void ModifyA(SearchInfo a) { a.Index = 99; a.Map[0] = 99; } void ModifyB(ref SearchInfo b) { b.Index = 99; b.Map[0] = 99; } struct SearchInfo { public int[] Map; public int Index; }

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  • mysql subselect alternative

    - by Arnold
    Hi, Lets say I am analyzing how high school sports records affect school attendance. So I have a table in which each row corresponds to a high school basketball game. Each game has an away team id and a home team id (FK to another "team table") and a home score and an away score and a date. I am writing a query that matches attendance with this seasons basketball games. My sample output will be (#_students_missed_class, day_of_game, home_team, away_team, home_team_wins_this_season, away_team_wins_this_season) I now want to add how each team did the previous season to my analysis. Well, I have their previous season stored in the game table but i should be able to accomplish that with a subselect. So in my main select statement I add the subselect: SELECT COUNT(*) FROM game_table WHERE game_table.date BETWEEN 'start of previous season' AND 'end of previous season' AND ( (game_table.home_team = team_table.id AND game_table.home_score > game_table.away_score) OR (game_table.away_team = team_table.id AND game_table.away_score > game_table.home_score)) In this case team-table.id refers to the id of the home_team so I now have all their wins calculated from the previous year. This method of calculation is neither time nor resource intensive. The Explain SQL shows that I have ALL in the Type field and I am not using a Key and the query times out. I'm not sure how I can accomplish a more efficient query with a subselect. It seems proposterously inefficient to have to write 4 of these queries (for home wins, home losses, away wins, away losses). I am sure this could be more lucid. I'll absolutely add color tomorrow if anyone has questions

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  • form change with javascript

    - by aslum
    I have two drop down lists <select name="branch"> <option value="b">Blacksburg</option> <option value="c">Christiansburg</option> <option value="f">Floyd</option> <option value="m">Meadowbrook</option> </select> but I would like the second list to be different based upon what is selected from the first list. So FREX Blacksburg's might be <select name="room"> <option value="Kitchen">Kitchen Side</option> <option value="Closet">Closet Side</option> <option value="Full">Full Room</option> </select While Christiansburg's is <select name="room"> <option value="Window">Window Side</option> <option value="Door">Door Side</option> <option value="Full">Full Room</option> and of course the options are also different for the other branches... Is it possible to change the second drop down list based on what they select for the first one? I have used javascript a teensy bit, but not much so please explain in detail. Thanks!

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  • What is difference between my atoi() calls?

    - by Lucas
    I have a big number stored in a string and try to extract a single digit. But what are the differences between those calls? #include <iostream> #include <string> int main(){ std::string bigNumber = "93485720394857230"; char tmp = bigNumber.at(5); int digit = atoi(&tmp); int digit2 = atoi(&bigNumber.at(5)) int digit3 = atoi(&bigNumber.at(12)); std::cout << "digit: " << digit << std::endl; std::cout << "digit2: " << digit2 << std::endl; std::cout << "digit3: " << digit3 << std::endl; } This will produce the following output. digit: 7 digit2: 2147483647 digit3: 57230 The first one is the desired result. The second one seems to me to be a random number, which I cannot find in the string. The third one is the end of the string, but not just a single digit as I expected, but up from the 12th index to the end of the string. Can somebody explain the different outputs to me? EDIT: Would this be an acceptable solution? char tmp[2] = {bigNumber.at(5), '\0'}; int digit = atoi(tmp); std::cout << "digit: " << digit << std::endl;

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  • Comprehending the Semantic web and it's methods, syntax, vocabularies and languages

    - by DreamCodeR
    Hi. I have just been introduced to the semantic web and it's family of functions but I have a hard time understanding some of it, which I was hoping someone could explain to me. As far as I've understood, RDF can be written in several syntaxes. RDF/XML, Turtle, etc. Now, I understand XML. How it is presented and how it can be parsed. However, some people write in the turtle syntax, but how do they parse that information? I can't seem to find a single library for any language to "extract" the information written in a turtle syntax into another form. The same goes for N3. How can it be used? Executed or else? I seem to be able to understand RDFa. That it is a way to implement RDF into XHTML. For me that is a way to implement RDF into "something". But how can I compare that to turtle, N3, or the like? Thanks in advance.

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  • PHP: MVC and Model

    - by Pirkka
    Hello I`ve been wondering this one thing about creating models. If I make for example Page model. Is it the both: It can retrieve one row from the table or all the rows. Somehow Im mixing the objects and the database. I have thought it like this: I would have to make a Page-class that would represent one row in the table. It also would have all the basic CRUD-methods. Then I would have to do a Pages-class (somekind of collection) that would retrieve rows from the table and instantiate a Page object from each row. Is this kind of weird? If someone could explain to me the idea of model throughout.. Im again confused. Maybe Im thinking the whole OOP too difficult.. And by the way this forum is great. Hopefully people will just understand my problems. Heh. I was a long time procedural style programmer and now in 3 months I have dived into OOP and MVC and PHP frameworks and I just get more excited day by day when I explore this stuff!

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  • Does this language feature already exists?

    - by Pindatjuh
    I'm currently developing a new language for programming in a continuous environment (compare it to electrical engineering), and I've got some ideas on a certain language construction. Let me explain the feature by explanation and then by definition; x = a | b; Where x is a variable and a and b are other variables (or static values). if(x == a) { // all references to "x" are essentially references to "a". } if(x == b) { // same but with "b" } if(x != a) { // ... } if(x == a | b) { // guaranteed that "x" is '"a" | "b"'; interacting with "x" // will interact with both "a" and "b". } // etc. In the above, all code-blocks are executed, but the "scope" changes in each block how x is interpreted. In the first block, x is guaranteed to be a: thus interacting with x inside that block will interact on a. The second and the third code-block are only equal in this situation (because not b only remains a). The last block guarantees that x is at least a or b. Further more; | is not the "bitwise or operator", but I've called it the "and/or"-operator. It's definition is: "|" = "and" | "or" (On my blog, http://cplang.wordpress.com/2009/12/19/binop-and-or/, is more (mathematical) background information on this operator. It's loosely based on sets.) I do not know if this construction already exists, so that's my question: does this language feature already exists?

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  • Redirecting from an update action to the referrer of the edit

    - by Mark Westling
    My Rails 2.3 application has a User model and the usual controller actions. The edit form can be reached two ways: when a user edits his own profile from the home page, or when an admin user edits someone else's profile from users collection. What I'd like to do is have the update action redirect back to the referred of the edit action, not the update action. If I do a simple redirect_to(:back) within update, it goes back to the edit form -- not good. One solution is to forget entirely about referrers and redirect based on the current_user and the updated user: if they're the same, go back to the home page, else go to the users collection page. This will break if I ever add a third path to the edit form. It's doubtful I'll ever do this but I'd prefer a solution that's not so brittle. Another solution is to store the referrer of edit form in a hidden field and then redirect to this value from inside the update action. This doesn't feel quite right, though I can't explain why. Are there any better approaches? Or, should I stop worrying and go with one of the two I've mentioned?

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  • rails semi-complex STI with ancestry data model planning the routes and controllers

    - by ere
    I'm trying to figure out the best way to manage my controller(s) and models for a particular use case. I'm building a review system where a User may build a review of several distinct types with a Polymorphic Reviewable. Country (has_many reviews & cities) Subdivision/State (optional, sometimes it doesnt exist, also reviewable, has_many cities) City (has places & review) Burrow (optional, also reviewable ex: Brooklyn) Neighborhood (optional & reviewable, ex: williamsburg) Place (belongs to city) I'm also wondering about adding more complexity. I also want to include subdivisions occasionally... ie for the US, I might add Texas or for Germany, Baveria and have it be reviewable as well but not every country has regions and even those that do might never be reviewed. So it's not at all strict. I would like it to as simple and flexible as possible. It'd kinda be nice if the user could just land on one form and select either a city or a country, and then drill down using data from say Foursquare to find a particular place in a city and make a review. I'm really not sure which route I should take? For example, what happens if I have a Country, and a City... and then I decide to add a Burrow? Could I give places tags (ie Williamsburg, Brooklyn) belong_to NY City and the tags belong to NY? Tags are more flexible and optionally explain what areas they might be in, the tags belong to a city, but also have places and be reviewable? So I'm looking for suggestions for anyone who's done something related. Using Rails 3.2, and mongoid.

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  • On saving an new active record, in what order are the associated objects saved?

    - by Bryan
    In rails, when saving an active_record object, its associated objects will be saved as well. But has_one and has_many association have different order in saving objects. I have three simplified models: class Team < ActiveRecord::Base has_many :players has_one :coach end class Player < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end class Coach < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end I expected that when team.save is called, team should be saved before its associated coach and players. I use the following code to test these models: t = Team.new team.coach = Coach.new team.save! team.save! returns true. But in another test: t = Team.new team.players << Player.new team.save! team.save! gives the following error: > ActiveRecord::RecordInvalid: > Validation failed: Players is invalid I figured out that team.save! saves objects in the following order: 1) players, 2) team, and 3) coach. This is why I got the error: When a player is saved, team doesn't yet have a id, so validates_presence_of :team_id fails in player. Can someone explain to me why objects are saved in this order? This seems not logical to me.

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  • ASP.Net MVC 2 - How to set up a Cancel button with client side navigation

    - by arame3333
    Thanks to a previous question I found a useful link on multiple buttons. http://weblogs.asp.net/dfindley/archive/2009/05/31/asp-net-mvc-multiple-buttons-in-the-same-form.aspx What I want to do is have a cancel button on my page, similar to this; <button name="button" type="button" onclick="document.location.href=$('#cancelUrl').attr('href')">Cancel</button> <a id="cancelUrl" href="<%: Url.Action("Index", "Home") %>" style="display:none;"></a> However although this code works, I really want to go back to the previous page. For Web Forms I could use the javascript Back() or Go(-1) functions, but they relied on postbacks. I could of course hard code the previous page and controller as I have done above. However I am struggling to find links that explain to me how Url.Action works. Because if I do this, I also need to include an index parameter, and I am not clear how the syntax works for that. It seems odd the amount of coding to do this. Out of curiosity, I am also wondering how you TDD client side code like this.

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  • CSS ] how to automatically resize the wrapper div.

    - by Phrixus
    Hi, I've been struggling with this problem.. There is a wrapper div and it contains 3 vertical column divs with full of texts, and this wrapper div has red background color so that it can be a background of the entire texts. <div id="content_wrapper"> <div id="cside_a"> // massive texts goes here </div> ... // two more columns go here. </div> And here is the CSS code for them. #content_wrapper { background-color:#DB0A00; background-repeat:no-repeat; min-height:400px; } #cside_a, #cside_b, #cside_c { float: left; width: 33%; } And this code gives me a background that covers only 400px height box.. My expectation was the wrapper div automatically resizes depending on the size of the divs in it. Somehow putting "overflow:hidden" with wrapper CSS code makes everything work fine. I have no idea why "overflow:hidden" works.. shouldn't this hide all the overflowed texts..? Could anyone explain me why? Is is the correct way to do it anyway?

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  • How can I use `pipe` to facilitate interprocess communication in Perl?

    - by Shiftbit
    Can anyone explain how I can successfully get my processes communicating? I find the perldoc on IPC confusing. What I have so far is: $| = 1; $SIG{CHLD} = {wait}; my $parentPid = $$; if ($pid = fork();) ) { if ($pid == 0) { pipe($parentPid, $$); open PARENT, "<$parentPid"; while (<PARENT>) { print $_; } close PARENT; exit(); } else { pipe($parentPid, $pid); open CHILD, ">$pid"; or error("\nError opening: childPid\nRef: $!\n"); open (FH, "<list") or error("\nError opening: list\nRef: $!\n"); while(<FH>) { print CHILD, $_; } close FH or error("\nError closing: list\nRef: $!\n"); close CHILD or error("\nError closing: childPid\nRef: $!\n); } else { error("\nError forking\nRef: $!\n"); } First: What does perldoc pipe mean by READHANDLE, WRITEHANDLE? Second: Can I implement a solution without relying on CPAN or other modules?

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