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  • JavaScript Show/Hide as Filters to list of divs

    - by deconspray
    Looking to create Javascript that acts like a filter on a list of divs. For instance, here's the intended markup... <a href="#" onclick="">Filter Item 1</a> <a href="#" onclick="">Filter Item 2</a> <a href="#" onclick="">Filter Item 3</a> <a href="#" onclick="">Filter Item 4</a> <a href="#" onclick="">Filter Item 5</a> <div class="1">Item 1</div> <div class="1">Item 1</div> <div class="2">Item 2</div> <div class="3">Item 3</div> <div class="1">Item 1</div> <div class="4">Item 4</div> <div class="4">Item 4</div> <div class="1">Item 1</div> <div class="5">Item 5</div> I want to be able to click on the link for Item 1, and show only Item 1 divs and hide all other divs, click the link of Item 2, and show only Item 2 divs and hide all other divs and so on. I've seen several similar scripts but nothing that seemingly turns divs matching the class on/off in this manner. TIA.

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  • "Permission denied" with Internet Explorer and jQuery

    - by rallex
    I try to do an AJAX call with jQuery and $.post in Internet Explorer, but all I get is an error saying "Permission denied". The problem is kinda weird since it occurs only when I access a page after I was on any other page. For instance I type the URL in the adress line and let IE load the page. Then I click on a button so the script should start loading JSON data. (The script providing the data lies on the same server and I access it with a relative URL, so using a different domain is not the problem here. Even tried to use a absolute URL with the same host part.) But when I refresh the page then and try it again it works! Same thing when I come to that page from another page. At first nothing works, but when I click "refresh" everything is fine. IE gives me the error message "Permission denied" while in every other browser I don't notice this behaviour. Since I have tried many things and still cannot imagine where the problem lies I'd like to ask you what you think the problem might be?

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  • How to output multiple rows from an SQL query using the mysqli object

    - by Jonathan
    Assuming that the mysqli object is already instantiatied (and connected) with the global variable $mysql, here is the code I am trying to work with. class Listing { private $mysql; function getListingInfo($l_id = "", $category = "", $subcategory = "", $username = "", $status = "active") { $condition = "`status` = '$status'"; if (!empty($l_id)) $condition .= "AND `L_ID` = '$l_id'"; if (!empty($category)) $condition .= "AND `category` = '$category'"; if (!empty($subcategory)) $condition .= "AND `subcategory` = '$subcategory'"; if (!empty($username)) $condition .= "AND `username` = '$username'"; $result = $this->mysql->query("SELECT * FROM listing WHERE $condition") or die('Error fetching values'); $this->listing = $result->fetch_array() or die('could not create object'); foreach ($this->listing as $key => $value) : $info[$key] = stripslashes(html_entity_decode($value)); endforeach; return $info; } } there are several hundred listings in the db and when I call $result-fetch_array() it places in an array the first row in the db. however when I try to call the object, I can't seem to access more than the first row. for instance: $listing_row = new Listing; while ($listing = $listing_row-getListingInfo()) { echo $listing[0]; } this outputs an infinite loop of the same row in the db. Why does it not advance to the next row? if I move the code: $this->listing = $result->fetch_array() or die('could not create object'); foreach ($this->listing as $key => $value) : $info[$key] = stripslashes(html_entity_decode($value)); endforeach; if I move this outside the class, it works exactly as expected outputting a row at a time while looping through the while statement. Is there a way to write this so that I can keep the fetch_array() call in the class and still loop through the records?

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  • Detecting what the target object is when NullReferenceException is thrown.

    - by StingyJack
    I'm sure we all have received the wonderfully vague "Object reference not set to instance of an Object" exception at some time or another. Identifying the object that is the problem is often a tedious task of setting breakpoints and inspecting all members in each statement. Does anyone have any tricks to easily and efficiently identify the object that causes the exception, either via programmatical means or otherwise? --edit It seems I was vague like the exception =). The point is to _not have to debug the app to find the errant object. The compiler/runtime does know that the object has been allocated, and that the object has not yet been instantiated. Is there a way to extract / identify those details in a caught exception @ W. Craig Trader Your explanation that it is a result of a design problem is probably the best answer I could get. I am fairly compulsive with defensive coding and have managed to get rid of most of these errors after fixing my habits over time. The remaining ones just tweak me to no end, and lead me to posting this question to the community. Thanks for everyone's suggestions.

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  • IIS7 URL Rewriting: How not to drop HTTPS protocol from rewritten URL?

    - by Scott Mitchell
    I'm working on a website that's using IIS 7's URL rewriting feature to do a permanent redirect from example.com to www.example.com, as well as rewrites from similar domain names to the "main" one, such as from www.examples.com to www.example.com. This rewrite rule - shown below - has worked well for sometime now. However, we recently added HTTPS support and noticed that if users visit one of the URLs to be rewritten to www.example.com then HTTPS is dropped. For instance, if a user visits https://example.com they get redirected to http://www.example.com, whereas we would like them to be sent to https://www.example.com. Here is the rewrite rule of interest (in Web.config): <rule name="Canonical Host Name" stopProcessing="true"> <match url="(.*)" /> <conditions logicalGrouping="MatchAny"> <add input="{HTTP_HOST}" pattern="^example\.com$" /> <add input="{HTTP_HOST}" pattern="^(www\.)?example\.net$" /> <add input="{HTTP_HOST}" pattern="^(www\.)?example\.info$" /> <add input="{HTTP_HOST}" pattern="^(www\.)?examples\.com$" /> </conditions> <action type="Redirect" url="http://www.example.com/{R:1}" redirectType="Permanent" /> </rule> As you can see, the action element's url attribute points directly to http://, so I get why https://example.com is redirected to http://www.example.com. My question is, how do I fix this? I tried (naively) to just drop the http:// part from the url attribute, but that didn't work. Thanks!

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  • Error In VB.Net code

    - by Michael
    I am getting the error "Format Exception was unhandled at "Do While objectReader.Peek < -1 " and after. any help would be wonderful. 'Date: Class 03/20/2010 'Program Purpose: When code is executed data will be pulled from a text file 'that contains the named storms to find the average number of storms during the time 'period chosen by the user and to find the most active year. between the range of 'years 1990 and 2008 Option Strict On Public Class frmHurricane Private _intNumberOfHuricanes As Integer = 5 Public Shared _intSizeOfArray As Integer = 7 Public Shared _strHuricaneList(_intSizeOfArray) As String Private _strID(_intSizeOfArray) As String Private _decYears(_intSizeOfArray) As Decimal Private _decFinal(_intSizeOfArray) As Decimal Private _intNumber(_intSizeOfArray) As Integer Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 'The frmHurricane load event reads the Hurricane text file and 'fill the combotBox object with the data. 'Initialize an instance of the StreamReader Object and declare variable page 675 on the book Dim objectReader As IO.StreamReader Dim strLocationAndNameOfFile As String = "C:\huricanes.txt" Dim intCount As Integer = 0 Dim intFill As Integer Dim strFileError As String = "The file is not available. Please restart application when available" 'This is where we code the file if it exist. If IO.File.Exists(strLocationAndNameOfFile) Then objectReader = IO.File.OpenText(strLocationAndNameOfFile) 'Read the file line by line until the file is complete Do While objectReader.Peek <> -1 **_strHuricaneList(intCount) = objectReader.ReadLine() _strID(intCount) = objectReader.ReadLine() _decYears(intCount) = Convert.ToDecimal(objectReader.ReadLine()) _intNumber(intCount) = Convert.ToInt32(objectReader.ReadLine()) intCount += 1** Loop objectReader.Close() 'With any luck the data will go to the Data Box For intFill = 0 To (_strID.Length - 1) Me.cboByYear.Items.Add(_strID(intFill)) Next Else MsgBox(strFileError, , "Error") Me.Close() End If End Sub

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  • Automating Excel through the PIA makes VBA go squiffy.

    - by Jon Artus
    I have absolutely no idea how to start diagnosing this, and just wondered if anyone had any suggestions. I'm generating an Excel spreadsheet by calling some Macros from a C# application, and during the generation process it somehow breaks. I've got a VBA class containing all of my logging/error-handling logic, which I instantiate using a singleton-esque accessor, shown here: Private mcAppFramework As csys_ApplicationFramework Public Function AppFramework() As csys_ApplicationFramework If mcAppFramework Is Nothing Then Set mcAppFramework = New csys_ApplicationFramework Call mcAppFramework.bInitialise End If Set AppFramework = mcAppFramework End Function The above code works fine before I've generated the spreadsheet, but afterwards fails. The problem seems to be the following line; Set mcAppFramework = New csys_ApplicationFramework which I've never seen fail before. If I add a watch to the variable being assigned here, the type shows as csys_ApplicationFramework/wksFoo, where wksFoo is a random worksheet in the same workbook. What seems to be happening is that while the variable is of the right type, rather than filling that slot with a new instance of my framework class, it's making it point to an existing worksheet instead, the equivalent of Set mcAppFramework = wksFoo which is a compiler error, as one might expect. Even more bizarrely, if I put a breakpoint on the offending line, edit the line, and then resume execution, it works. For example, I delete the word 'New' move off the line, move back, re-type 'New' and resume execution. This somehow 'fixes' the workbook and it works happily ever after, with the type of the variable in my watch window showing as csys_ApplicationFramework/csys_ApplicationFramework as I'd expect. This implies that manipulating the workbook through the PIA is somehow breaking it temporarily. All I'm doing in the PIA is opening the workbook, calling several macros using Excel.Application.Run(), and saving it again. I can post a few more details if anyone thinks that it's relevant. I don't know how VBA creates objects behind the scenes or how to debug this. I also don't know how the way the code executes can change without the code itself changing. As previously mentioned, VBA has frankly gone a bit squiffy on me... Any thoughts?

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  • What is a better, cleaner way of using List<T>

    - by Tim Meers
    I'm looking to implement a few nicer ways to use List in a couple of apps I'm working on. My current implementation looks like this. MyPage.aspx.cs protected void Page_Load(object sender, EventArgs e) { BLL.PostCollection oPost = new BLL.PostCollection(); oPost.OpenRecent(); rptPosts.DataSource = oArt; rptPosts.DataBind(); } BLL Class(s) public class Post { public int PostId { get; set; } public string PostTitle { get; set; } public string PostContent { get; set; } public string PostCreatedDate { get; set; } public void OpenRecentInitFromRow(DataRow row) { this.PostId = (int) row["id"]; this.PostTitle = (string) row["title"]; this.PostContent = (string) row["content"]; this.PostCreatedDate = (DateTime) row["createddate"]; } } public class PostCollection : List<Post> { public void OpenRecent() { DataSet ds = DbProvider.Instance().Post_ListRecent(); foreach (DataRow row in ds.Tables[0].Rows) { Post oPost = new Post(); oPost.OpenRecentInitFromRow(row); Add(oPost); } } } Now while this is working all well and good, I'm just wondering if there is any way to improve it, and just make it cleaner that having to use the two different classes do to something I think can happen in just one class or using an interface.

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  • Java: multi-threaded maps: how do the implementations compare?

    - by user346629
    I'm looking for a good hash map implementation. Specifically, one that's good for creating a large number of maps, most of them small. So memory is an issue. It should be thread-safe (though losing the odd put might be an OK compromise in return for better performance), and fast for both get and put. And I'd also like the moon on a stick, please, with a side-order of justice. The options I know are: HashMap. Disastrously un-thread safe. ConcurrentHashMap. My first choice, but this has a hefty memory footprint - about 2k per instance. Collections.sychronizedMap(HashMap). That's working OK for me, but I'm sure there must be faster alternatives. Trove or Colt - I think neither of these are thread-safe, but perhaps the code could be adapted to be thread safe. Any others? Any advice on what beats what when? Any really good new hash map algorithms that Java could use an implementation of? Thanks in advance for your input!

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  • Class lookup structure array in C++

    - by wyatt
    I'm trying to create a structure array which links input strings to classes as follows: struct {string command; CommandPath cPath;} cPathLookup[] = { {"set an alarm", AlarmCommandPath}, {"send an email", EmailCommandPath}, {"", NULL} }; which will be used as follows: CommandPath *cPath = NULL; string input; getline(cin, input); for(int i = 0; cPathLookup[i] != ""; i++) { if(cPathLookup[i].command == input) cPath = new cPathLookup[i].cPath; } Obviously, this code is meaningless, but I think my intention is apparent - depending on input, I'd like cPath to be initialized as either a new AlarmCommandPath or a new EmailCommandPath. I could handle it with a function returning an instance depending on input, but a whole sequence of ifs just seems inelegant. I should also note that, in case it's not apparent and important, that AlarmCommandPath and EmailCommandPath are derived from CommandPath, and CommandPath is an abstract class. Thanks for any help you can offer. EDIT: I just noticed that, in spite of CommandPath being abstract, I have a declaration: CommandPath *cPath = NULL; in working code. Why does that compile?

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  • Require reasonably random results from an SQL SELECT query within a Joomla article (Cache enabled)

    - by Shrinivas
    Setup: Joomla website on LAMP stack I have a MySQL table containing some records, these are queried by a simple SELECT on the Joomla article, as pasted below. This specific Joomla website has Caching turned on in Joomla's Global Configuration. I need to randomize the order in which I display the resultset, each time the page is loaded. Regular php/mysql would offer me two approaches for this: 1. use 'order by RAND()' or any of a number of methods to allow a SELECT query to return reasonably random results. 2. once php gets the result from the SELECT into an array, shuffle the array to get a reasonably random order of array items. However, as this Joomla instance has Caching turned ON in its Global Configuration, either of the above approaches fails. The first time I load the page the order is randomized, however any further reloads do not cause the order to change, as the page is delivered from cache. The instant the Cache is disabled, both approaches (shuffle/order by rand) work perfectly. What am I missing? How do I override the Global Cache for this specific article? A very simple requirement, that is met by both php and mysql reasonably well, is blocked by the Joomla Cache that I cannot turn off. The php that returns results from the database. <pre> $db = JFactory::getDBO(); $select = "SELECT id FROM jos_mytable;"; //order by RAND() $db->setQuery($select); echo $db->getQuery(); //Show me the Query! $rows = $db->loadObjectList(); //shuffle($rows); foreach($rows as $row) { echo "$row->id"; }

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  • Error using maven profiles

    - by user3127896
    I've added two profiles to my application and that how it looks: <profiles> <profile> <id>dev</id> <properties> <db.username>root</db.username> <db.password>root</db.password> <db.connectionURL>localhost:3306</db.connectionURL> <db.driverClass>com.mysql.jdbc.Driver</db.driverClass> </properties> </profile> <profile> <id>prod</id> <properties> <db.username>prodroot</db.username> <db.password>prodpass</db.password> <db.connectionURL>localhost:3306</db.connectionURL> <db.driverClass>com.mysql.jdbc.Driver</db.driverClass> </properties> </profile> </profiles> In my jdbc.properties file i changed values like this: jdbc.driverClassName=${db.driverClass} jdbc.dialect=org.hibernate.dialect.MySQLDialect jdbc.databaseurl=jdbc:mysql://${db.connectionURL}/dbname jdbc.username=${db.username} jdbc.password=${db.password} And here's bean from spring-container.xml <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" p:driverClassName="${jdbc.driverClassName}" p:url="${jdbc.databaseurl}" p:username="${jdbc.username}" p:password="${jdbc.password}" /> When i try to deploy my application i got following error: SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener org.springframework.beans.factory.BeanDefinitionStoreException: Invalid bean definition with name 'dataSource' defined in ServletContext resource [/WEB-INF/spring-servlet.xml]: Could not resolve placeholder 'db.driverClass' Structure of project: Any ideas what i'm doing wrong? Thanks in advance!

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  • Getting the current item number or index when using will_paginate in rails app

    - by Rich
    I have a rails app that stores movies watched, books read, etc. The index page for each type lists paged collections of all its items, using will_paginate to bring back 50 items per page. When I output the items I want to display a number to indicate what item in the total collection it is. The numbering should be reversed as the collection is displayed with most recent first. This might not relate to will_paginate but rather some other method of calculation. I will be using the same ordering in multiple types so it will need to be reusable. As an example, say I have 51 movies. The first item of the first page should display: Fight Club - Watched: 30th Dec 2010 Whilst the last item on the page should display: The Matrix - Watched: 3rd Jan 2010 The paged collection is available as an instance variable e.g. @movies, and @movies.count will display the number of items in the paged collection. So if we're on page 1, movies.count == 50, whilst on page 2 @movies.count == 1. Using Movie.count would give 51. If the page number and page size can be accessed the number could be calculated so how can they be returned? Though I'm hopeful there is something that already exists to handle this calculation!

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  • (Java) Get value of string loaded into dynamic-type object?

    - by Michael
    I'm very new to Java (~10 days), so my code is probably pretty bad, but here's what I've got: ArgsDataHolder argsData = new ArgsDataHolder(); // a class that holds two // ArrayList's where each element // representing key/value args Class thisArgClass; String thisArgString; Object thisArg; for(int i=2; i< argsString.length; i++) { thisToken = argsString[i]; thisArgClassString = getClassStringFromToken(thisToken).toLowerCase(); System.out.println("thisArgClassString: " + thisArgClassString); thisArgClass = getClassFromClassString(thisArgClassString); // find closing tag; concatenate middle Integer j = new Integer(i+1); thisArgString = getArgValue(argsString, j, "</" + thisArgClassString + ">"); thisArg = thisArgClass.newInstance(); thisArg = thisArgClass.valueOf(thisArgString); argsData.append(thisArg, thisArgClass); } The user basically has to input a set of key/value arguments into the command prompt in this format: <class>value</class>, e.g. <int>62</int>. Using this example, thisArgClass would be equal to Integer.class, thisArgString would be a string that read "62", and thisArg would be an instance of Integer that is equal to 62. I tried thisArg.valueOf(thisArgString), but I guess valueOf(<String>) is only a method of certain subclasses of Object. For whatever reason, I can't seem to be able to cast thisArg to thisArgClass (like so: thisArg = (thisArgClass)thisArgClass.newInstance();, at which point valueOf(<String>) should become accessible. There's got to be a nice, clean way of doing this, but it is beyond my abilities at this point. How can I get the value of the string loaded into a dynamically-typed object (Integer, Long, Float, Double, String, Character, Boolean, etc.)? Or am I just overthinking this, and Java will do the conversion for me? :confused:

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  • User submitted content filtering

    - by Jim
    Hey all, Does anyone have any ideas on what could be used as a way to filter untrustworthy user submitted content? Take Yelp for instance, they would need to prevent competitors writing business reviews on their competitors. They would need to prevent business owners favourably reviewing their own business, or forcing friends/family to do so. They would need to prevent poor quality reviews from affecting a businesses rating and so on. I can't think what they might use to do this: Prevent multiple users from the same IP reviewing certain things Prevent business owners reviewing their own business (maybe even other businesses in the same categories as their own?) Somehow determine what a review is about and what the actual intentions behind it are Other than the first and second points, I can't think of any clever/easy way to filter potentially harmful reviews from being made available, other than a human doing it. Obviously for a site the size of Yelp this wouldn't be feasible, so what parameters could they take into consideration? Even with human intervention, how would anyone know it was the owners best buddy writing a fake review without knowing the people? I'm using this as an example in a larger study on the subject of filtering user content automatically. Does anyone have any ideas how these systems may work and what they take into consideration? Thanks!

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  • Conditional compilation hackery in C# - is there a way to pull this off?

    - by Chris
    I have an internal API that I would like others to reference in their projects as a compiled DLL. When it's a standalone project that's referenced, I use conditional compilation (#if statements) to switch behavior of a key web service class depending on compilation symbols. The problem is, once an assembly is generated, it appears that it's locked into whatever the compilation symbols were when it was originally compiled - for instance, if this assembly is compiled with DEBUG and is referenced by another project, even if the other project is built as RELEASE, the assembly still acts as if it was in DEBUG as it doesn't need recompilation. That makes sense, just giving some background. Now I'm trying to work around that so I can switch the assembly's behavior by some other means, such as scanning the app/web config file for a switch. The problem is, some of the assembly's code I was switching between are attributes on methods, for example: #if PRODUCTION [SoapDocumentMethodAttribute("https://prodServer/Service_Test", RequestNamespace = "https://prodServer", ResponseNamespace = "https://prodServer")] #else [SoapDocumentMethodAttribute("https://devServer/Service_Test", RequestNamespace = "https://devServer", ResponseNamespace = "https://devServer")] #endif public string Service_Test() { // test service } Though there might be some syntactical sugar that allows me to flip between two attributes of the same type in another fashion, I don't know it. Any ideas? The alternative method would be to reference the entire project instead of the assembly, but I'd rather stick with just referencing the compiled DLL if I can. I'm also completely open to a whole new approach to solve the problem if that's what it takes.

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  • Creating Linear Layout with TextViews using a for loop

    - by cad8
    Hi all, I was wondering if there is a way to dynamically create an additional linear layout with a textview within a predefined liner layout. THis is my code so you get the gist of what I am asking: LinearLayout MainLL= (LinearLayout) findViewById(R.id.myLayoutId); for(int i=0; i<5; i++) { LinearLayout childLL= new LinearLayout(this); childLL.setOrientation(LinearLayout.VERTICAL); childLL.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT)); childLL.setGravity(Gravity.LEFT); TextView text = new TextView(this); text.setText("The Value of i is :"i); text.setTextSize(12); text.setGravity(Gravity.LEFT); text.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT)); childLL.addView(text); MainLL.addView(childLL); } My problem is that I am only getting "The Value of i is :0" as the output, i.e. the first instance. Any help would be much appreciated

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  • Conflict with @Html.LabelFor and W3C Validator?

    - by Tyler
    I have a model that I am using to present an index of a model from a database and have given a display name to some of the rows that may need spaces in them, (I.e. "weekstarting" in a db would be given a display name of "Week Starting"). So I set the display name for my model like this: [DisplayName("Week Starting")] public DateTime WeekStarting { get; set; } and then in the table headers for my table I use the following line of code to display the field name using its given display name: @Html.LabelFor(x => x.First().WeekStarting) The above all works fine. But I am using the W3C validator and it is giving me the following error for the example I have given: The for attribute of the label element must refer to a form control. Forgive me if it is obvious but what am I doing wrong here? I am not using a form I am simply displaying an index of items in a table. I have tried to look for an answer and saw someone suggest that the form controls being referred to need ids (even though I'm not using a form) but this would not be applicable in this instance because if I tried to set an id in the index it would be duplicated with each item in the index: foreach (var item in Model.Tbms) { <tr><td>@item.value</td><tr>.... would be repeated for each item, and also unsure where I would put the id in any case, the td? } Or is there a better way to label the field header, with my preferred display name in the first place? I guess I could just swap @Html.LabelFor... for Hard code field name but do I have to?

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  • Is False == 0 and True == 1 in Python an implementation detail or guaranteed by the language?

    - by EOL
    Is it guaranteed that False == 0 and True == 1, in Python? For instance, is it in any way guaranteed that the following code will always produce the same results, whatever the version of Python (existing and in the foreseeable future)? 0 == False # True 1 == True # True ['zero', 'one'][False] # is 'zero' Any reference to the official documentation would be much appreciated! Other comments would be appreciated too… :) Edit: As noted in many answers, bool inherits from int. The question can therefore be recast as: "Is this an implementation detail that might change in the future, or does the documentation officially say that programmers can rely on booleans inheriting from integers?". This question is relevant for writing robust code that won't fail because of implementation details! Edit 2: The original question is still open, I believe (even though I accepted what I thought was the closest answer): even though Python 3 officially recognizes booleans as integers, I have not yet seen any official integer values for False and True… It therefore looks to me like it is best to stay clear from the assumption that False==0 and True==1.

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  • How to find sum of node's value for given depth in binary tree?

    - by masato-san
    I've been scratching my head for several hours for this... problem: Binary Tree (0) depth 0 / \ 10 20 depth 1 / \ / \ 30 40 50 60 depth 2 I am trying to write a function that takes depth as argument and return the sum of values of nodes of the given depth. For instance, if I pass 2, it should return 180 (i.e. 30+40+50+60) I decided to use breath first search and when I find the node with desired depth, sum up the value, but I just can't figure out how to find out the way which node is in what depth. But with this approach I feel like going to totally wrong direction. function level_order($root, $targetDepth) { $q = new Queue(); $q->enqueue($root); while(!$q->isEmpty) { //how to determin the depth of the node??? $node = $q->dequeue(); if($currentDepth == $targetDepth) { $sum = $node->value; } if($node->left != null) { $q->enqueue($node->left); } if($node->right != null) { $q->enqueue($node->right); } //need to reset this somehow $currentDepth ++; } }

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  • Has inheritance become bad?

    - by mafutrct
    Personally, I think inheritance is a great tool, that, when applied reasonably, can greatly simplify code. However, I seems to me that many modern tools dislike inheritance. Let's take a simple example: Serialize a class to XML. As soon as inheritance is involved, this can easily turn into a mess. Especially if you're trying to serialize a derived class using the base class serializer. Sure, we can work around that. Something like a KnownType attribute and stuff. Besides being an itch in your code that you have to remember to update every time you add a derived class, that fails, too, if you receive a class from outside your scope that was not known at compile time. (Okay, in some cases you can still work around that, for instance using the NetDataContract serializer in .NET. Surely a certain advancement.) In any case, the basic principle still exists: Serialization and inheritance don't mix well. Considering the huge list of programming strategies that became possible and even common in the past decade, I feel tempted to say that inheritance should be avoided in areas that relate to serialization (in particular remoting and databases). Does that make sense? Or am messing things up? How do you handle inheritance and serialization?

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  • Is this a reasonable way to handle getters/setters in a PHP class?

    - by Mark Biek
    I'm going to try something with the format of this question and I'm very open to suggestions about a better way to handle it. I didn't want to just dump a bunch of code in the question so I've posted the code for the class on refactormycode. base-class-for-easy-class-property-handling My thought was that people can either post code snippets here or make changes on refactormycode and post links back to their refactorings. I'll make upvotes and accept an answer (assuming there's a clear "winner") based on that. At any rate, on to the class itself: I see a lot of debate about getter/setter class methods and is it better to just access simple property variables directly or should every class have explicit get/set methods defined, blah blah blah. I like the idea of having explicit methods in case you have to add more logic later. Then you don't have to modify any code that uses the class. However I hate having a million functions that look like this: public function getFirstName() { return $this->firstName; } public function setFirstName($firstName) { return $this->firstName; } Now I'm sure I'm not the first person to do this (I'm hoping that there's a better way of doing it that someone can suggest to me). Basically, the PropertyHandler class has a __call magic method. Any methods that come through __call that start with "get" or "set" are then routed to functions that set or retrieve values into an associative array. The key into the array is the name of the calling method after get or set. So, if the method coming into __call is "getFirstName", the array key is "FirstName". I liked using __call because it will automatically take care of the case where the subclass already has a "getFirstName" method defined. My impression (and I may be wrong) is that the __get & __set magic methods don't do that. So here's an example of how it would work: class PropTest extends PropertyHandler { public function __construct() { parent::__construct(); } } $props = new PropTest(); $props->setFirstName("Mark"); echo $props->getFirstName(); Notice that PropTest doesn't actually have "setFirstName" or "getFirstName" methods and neither does PropertyHandler. All that's doing is manipulating array values. The other case would be where your subclass is already extending something else. Since you can't have true multiple inheritance in PHP, you can make your subclass have a PropertyHandler instance as a private variable. You have to add one more function but then things behave in exactly the same way. class PropTest2 { private $props; public function __construct() { $this->props = new PropertyHandler(); } public function __call($method, $arguments) { return $this->props->__call($method, $arguments); } } $props2 = new PropTest2(); $props2->setFirstName('Mark'); echo $props2->getFirstName(); Notice how the subclass has a __call method that just passes everything along to the PropertyHandler __call method. Another good argument against handling getters and setters this way is that it makes it really hard to document. In fact, it's basically impossible to use any sort of document generation tool since the explicit methods to be don't documented don't exist. I've pretty much abandoned this approach for now. It was an interesting learning exercise but I think it sacrifices too much clarity.

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  • How to avoid raising an event to a closed form?

    - by Steve Dignan
    I'm having trouble handling the scenario whereby an event is being raised to a closed form and was hoping to get some help. Scenario (see below code for reference): Form1 opens Form2 Form1 subscribes to an event on Form2 (let's call the event FormAction) Form1 is closed and Form2 remains open Form2 raises the FormAction event In Form1.form2_FormAction, why does this return a reference to Form1 but button1.Parent returns null? Shouldn't they both return the same reference? If we were to omit step 3, both this and button1.Parent return the same reference. Here's the code I'm using... Form1: public partial class Form1 : Form { public Form1 () { InitializeComponent(); } private void button1_Click ( object sender , EventArgs e ) { // Create instance of Form2 and subscribe to the FormAction event var form2 = new Form2(); form2.FormAction += form2_FormAction; form2.Show(); } private void form2_FormAction ( object o ) { // Always returns reference to Form1 var form = this; // If Form1 is open, button1.Parent is equal to form/this // If Form1 is closed, button1.Parent is null var parent = button1.Parent; } } Form2: public partial class Form2 : Form { public Form2 () { InitializeComponent(); } public delegate void FormActionHandler ( object o ); public event FormActionHandler FormAction = delegate { }; private void button1_Click ( object sender , EventArgs e ) { FormAction( "Button clicked." ); } } Ideally, I would like to avoid raising events to closed/disposed forms (which I'm not sure is possible) or find a clean way of handling this in the caller (in this case, Form1). Any help is appreciated.

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  • How to handle ids and polymorphic associations in views if compound keys are not supported?

    - by duncan
    I have a Movie plan table: movie_plans (id, description) Each plan has items, which describe a sequence of movies and the duration in minutes: movie_plan_items (id, movie_plan_id, movie_id, start_minutes, end_minutes) A specific instance of that plan happens in: movie_schedules (id, movie_plan_id, start_at) However the schedule items can be calculated from the movie_plan_items and the schedule start time by adding the minutes create view movie_schedule_items as select CONCAT(p.id, '-', s.id) as id, s.id as movie_schedule_id, p.id as movie_plan_item_id, p.movie_id, p.movie_plan_id, (s.start_at + INTERVAL p.start_minutes MINUTE) as start_at, (s.start_at + INTERVAL p.end_minutes MINUTE) as end_at from movie_plan_items p, movie_schedules s where s.movie_plan_id=p.movie_plan_id; I have a model over this view (readonly), it works ok, except that the id is right now a string. I now want to add a polymorphic property (like comments) to various of the previous tables. Therefore for movie_schedule_items I need a unique and persistent numeric id. I have the following dilemma: I could avoid the id and have movie_schedule_items just use the movie_plan_id and movie_schedule_id as a compound key, as it should. But Rails sucks in this regard. I could create an id using String#hash or a md5, thus making it slower or collision prone (and IIRC String#hash is no longer persistent across processes in Ruby 1.9) Any ideas on how to handle this situation?

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  • C Program not running as intended, hangs after input

    - by user41419
    The program I am writing to take a number and display that number as a calculator would display it (shown below) is compiling with no issues, but when I try to run it, I am able to input my number, but nothing happens. It seems like it is "hanging", since no further output is shown as I would have expected. Might anyone know what the problem is? #include <stdio.h> #define MAX_DIGITS 20 char segments[10][7] = /* seven segment array */ {{'1','1','1','1','1','1','0'}, /* zero */ {'0','1','1','0','0','0','0'}, /* one */ {'1','1','0','1','1','0','1'}, /* two */ {'1','1','1','1','0','0','1'}, /* three */ {'0','1','1','0','0','1','1'}, /* four */ {'1','0','1','1','0','1','1'}, /* five */ {'1','0','1','1','1','1','1'}, /* six */ {'1','1','1','0','0','0','0'}, /* seven */ {'1','1','1','1','1','1','1'}, /* eight */ {'1','1','1','0','0','1','1'}};/* nine */ char digits[3][MAX_DIGITS * 4]; /* digits array */ int i, j; /* count variables */ int adjust; /* output formatting */ int main(void) { clear_digits_array(); int digit[20]; for (i = 0; i < 20; i++) { digit[i] = 0; } int count = 20; int position = 0; printf("Enter a number: "); int number = scanf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", &digit[0], &digit[1], &digit[2], &digit[3], &digit[4], &digit[5], &digit[6], &digit[7], &digit[8], &digit[9], &digit[10], &digit[11], &digit[12], &digit[13], &digit[14], &digit[15], &digit[16], &digit[17], &digit[18], &digit[19]); //NOTHING HAPPENS AFTER HERE printf("Got input, number is %d", number); while (count > 0) { printf("Reading digits, count is %d", count); process_digit(digit[20 - count], position); position++; count--; } print_digits_array(); printf("\n"); return 0; } void clear_digits_array(void) { /* fill all positions in digits array with blank spaces */ for (i = 0; i < 3; i++) { for (j = 0; j < (MAX_DIGITS * 4); j++) { digits[i][j] = ' '; } } } void process_digit(int digit, int position) { /* check each segment to see if segment should be filled in for given digit */ for (i = 0; i < 7; i++) { printf("Processing digit %d at position %d, i is %d", digit, position, i); if (segments[digit][i] == 1) { switch (i) { case 0: digits[0][(position * 4) + 1] = '_'; break; case 1: digits[1][(position * 4) + 2] = '|'; break; case 2: digits[2][(position * 4) + 2] = '|'; break; case 3: digits[2][(position * 4) + 1] = '_'; break; case 4: digits[2][(position * 4) + 0] = '|'; break; case 5: digits[1][(position * 4) + 0] = '|'; break; case 6: digits[1][(position * 4) + 1] = '_'; break; } } } } void print_digits_array(void) { /* print each character in digits array */ for (i = 0; i < 3; i++) { for (j = 0; j < (MAX_DIGITS * 4); j++) { printf("%c", digits[i][j]); } printf("/n"); } }

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