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• Should I re-use UI elements across view controllers?

  - by Endemic

  In the iPhone app I'm currently working on, I'd like two navigation controllers (I'll call them A and B) to have toolbars that are identical in appearance and function. The toolbar in question will look like this: [(button) (flexible-space) (label)] For posterity's sake, the label is actually a UIBarButtonItem with a custom view. My design requires that A always appear directly before B on the navigation stack, so B will never be loaded without A having been loaded. Given this layout, I started wondering, "Is it worth it to re-use A's toolbar items in B's toolbar?" As I see it, my options are: 1. Don't worry about re-use, create the toolbar items twice 2. Create the toolbar items in A and pass them to B in a custom initializer 3. Use some more obscure method that I haven't thought of to hold the toolbar constant when pushing a view controller As far as I can see, option 1 may violate DRY, but guarantees that there won't be any confusion on the off chance that (for example) the button may be required to perform two different (no matter how similar) functions for either view controller in future versions of the app. Were that to happen, options 2 or 3 would require the target-action of the button to change when B is loaded and unloaded. Even if the button were never required to perform different functions, I'm not sure what its proper target would be under option 2. All in all, it's not a huge problem, even if I have to go with option 1. I'm probably overthinking this anyway, trying to apply the dependency injection pattern where it's not appropriate. I just want to know the best practice should this situation arise in a more extreme form, like if a long chain of view controllers need to use identical (in appearance and function) UI elements.

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• Execute client & server side code with one click?

  - by Abu Hamzah

  i am not sure if my design have flaw but would like to know what others have to say, i am in a situation where i am trying to acheive two things in one click. using : asp.net web form i have a web form with few textbox and a gridview control and a button. if i click on the button i am executing two things 1) asynchronously get data from server to client (working great) and able to display the data in the textboxes. 2) same click i want to bind the gridview. <asp:Content ID="Content2" ContentPlaceHolderID="cphMaster" runat="server"> <asp:Label runat="server" ID='Label1' >Id:</asp:Label> <asp:TextBox ID="txtId" runat='server'></asp:TextBox> <asp:Button ID="btnSubmit" OnClientClick="LoadDataById();" runat="server" Text="Submit" onclick="btnSubmit_Click" /> <br /> <br /> <asp:TextBox ID="txtName" runat='server'></asp:TextBox> <br /> <asp:TextBox ID="txtPurpose" runat='server'></asp:TextBox> <br /> <br /> <asp:GridView ID="GridView1" runat="server"> </asp:GridView> </asp:Content> server side protected void btnSubmit_Click(object sender, EventArgs e) { GridView1.DataSource = laodData(int.Parse(txtId.Text)); GridView1.DataBind(); } Jquery: function LoadVisitBasicByVisitId() { ContactServiceProxy.invoke({ serviceMethod: "GetDataById", data: { request: request }, callback: function(response) { processCompletedContactStore(response); }, error: function(xhr, errorMsg, thrown) { postErrorAndUnBlockUI(xhr, errorMsg, thrown); } }); return false; } recap: 1) jquery script execute asynchronously to get data from server to client and display in the textboxes 2) server side code to bind the gridview.

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• Comparing lists of field-hashes with equivalent AR-objects.

  - by Tim Snowhite

  I have a list of hashes, as such: incoming_links = [ {:title => 'blah1', :url => "http://blah.com/post/1"}, {:title => 'blah2', :url => "http://blah.com/post/2"}, {:title => 'blah3', :url => "http://blah.com/post/3"}] And an ActiveRecord model which has fields in the database with some matching rows, say: Link.all => [<Link#2 @title='blah2' @url='...post/2'>, <Link#3 @title='blah3' @url='...post/3'>, <Link#4 @title='blah4' @url='...post/4'>] I'd like to do set operations on Link.all with incoming_links so that I can figure out that <Link#4 ...> is not in the set of incoming_links, and {:title => 'blah1', :url =>'http://blah.com/post/1'} is not in the Link.all set, like so: #pseudocode #incoming_links = as above links = Link.all expired_links = links - incoming_links missing_links = incoming_links - links expired_links.destroy missing_links.each{|link| Link.create(link)} One route I've tried: I'd rather not rewrite Array#- and such, and I'm okay with converting incoming_links to a set of unsaved Link objects; so I've tried overwriting hash eql? and so on in Link so that it ignored the id equality that AR::Base provides by default. But this is the only place this sort of equality should be considered in the application - in other places the Link#id default identity is required. Is there some way I could subclass Link and apply the hash, eql?, etc overwriting there? The other route I've tried is to pull out the attributes hash for each Link and doing a .slice('id',...etc) to prune the hashes down. But this requires writing seperate methods for keeping track of the Link objects while doing set operations on the hashes, or writing seperate Collection classes to wrap the incoming_links hash-list and Link-list which seems a bit overkill. What is the best way to design this interaction? Extra credit for cleanliness.

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• has_many :through default values

  - by David Lyod

  I have a need to design a system to track users memberships to groups with varying roles (currently three). class Group < ActiveRecord::Base has_many :memberships has_many :users, :through => :memberships end class Role < ActiveRecord::Base has_many :memberships has_many :users, :through => :memberships end class Membership < ActiveRecord::Base belongs_to :user belongs_to :role belongs_to :group end class User < ActiveRecord::Base has_many :memberships has_many :groups, :through => :memberships end Ideally what I want is to simply set @group.users << @user and have the membership have the correct role. I can use :conditions to select data that has been manually inserted as such : :conditions => ["memberships.grouprole_id= ? ", Grouprole.find_by_name('user')] But when creating the membership to the group the grouprole_id is not being set. Is there a way to do this as at present I have a somewhat repetitive piece of code for each user role in my Group model.

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• two view controllers and reusability with delegate

  - by netcharmer

  Newbie question about design patterns in objC. I'm writing a functionality for my iphone app which I plan to use in other apps too. The functionality is written over two classes - Viewcontroller1 and Viewcontroller2. Viewcontroller1 is the root view of a navigation controller and it can push Viewcontroller2. Rest of the app will use only ViewController1 and will never access Viewcontroller2 directly. However, triggered by user events, Viewcontroller2 has to send a message to the rest of the app. My question is what is the best way of achieving it? Currently, I use two level of delegation to send the message out from Viewcontroller2. First send it to Viewcontroller1 and then let Viewcontroller1 send it to rest of the app or the application delegate. So my code looks like - //Viewcontroller1.h @protocol bellDelegate -(int)bellRang:(int)size; @end @interface Viewcontroller1 : UITableViewController <dummydelegate> { id <bellDelegate> delegate; @end //Viewcontroller1.m @implementation Viewcontroller1 -(void)viewDidLoad { //some stuff here Viewcontroller2 *vc2 = [[Viewcontroller2 alloc] init]; vc2.delegate = self; [self.navigationController pushViewController:vc2 animated:YES]; } -(int)dummyBell:(int)size { return([self.delegate bellRang:size]); } //Viewcontroller2.h @protocol dummyDelegate -(int)dummyBell:(int)size; @end @interface Viewcontroller2 : UITableViewController { id <dummyDelegate> delegate; @end //Viewcontroller2.m @implementation Viewcontroller2 -(int)eventFoo:(int)size { rval = [self.delegate dummyBell:size]; } @end

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• specified size of td

  - by ognjenb

  <table class="data-table"> <tr> <th style="width: 200px;"> Description </th> </tr> <% foreach (var item in Model) { %> <tr> <td style="width: 200px;"> <%= Html.Encode(item.Description) %> </td> </tr> </table> browser html: <table class="data-table"> <tr> <th style="width: 200px;"> Description </th> </tr> <tr> <td > This is description </td> </tr> </table> Why this td size is not to apply on View page? In Design view on VS 2008 td size is applied, but after run project in my browser not have specified size

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• Calling member functions dynamically

  - by user652511

  I'm pretty sure it's possible to call a class and its member function dynamically in Delphi, but I can't quite seem to make it work. What am I missing? // Here's a list of classes (some code removed for clarity) moClassList : TList; moClassList.Add( TClassA ); moClassList.Add( TClassB ); // Here is where I want to call an object's member function if the // object's class is in the list: for i := 0 to moClassList.Count - 1 do if oObject is TClass(moClassList[i]) then with oObject as TClass(moClassList[i]) do Foo(); I get an undeclared identifier for Foo() at compile. Clarification/Additional Information: What I'm trying to accomplish is to create a Change Notification system between business classes. Class A registers to be notified of changes in Class B, and the system stores a mapping of Class A - Class B. Then, when a Class B object changes, the system will call a A.Foo() to process the change. I'd like the notification system to not require any hard-coded classes if possible. There will always be a Foo() for any class that registers for notification. Maybe this can't be done or there's a completely different and better approach to my problem. By the way, this is not exactly an "Observer" design pattern because it's not dealing with objects in memory. Managing changes between related persistent data seems like a standard problem to be solved, but I've not found very much discussion about it. Again, any assistance would be greatly appreciated. Jeff

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• RESTful API: How to model JSON representation?

  - by Jan P.

  I am designing a RESTful API for a booking application. You can request a list of accommodations. And that's where I don't really know how to design the JSON represenation. This is my XML representation: <?xml version="1.0" encoding="utf-8"?> <accommodations> <accommodation> <name>...</name> <category>couch</category> </accommodation> <accommodation> <name>...</name> <category>room</category> </accommodation> <accommodations> My first try to convert this to JSON resulted in this output (1): { "0": { "name": "...", "category": "couch" }, "1": { "name": "...", "category": "room" } } But as I looked how others APIs did it, I found something looking more like this (2): [ { "name": "...", "category": "couch" }, { "name": "...", "category": "room" } ] I know version 1 is an object, and version 2 an array. But which one is better in this case?

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• Objective C - creating concrete class instances from base class depending upon type

  - by indiantroy

  Just to give a real world example, say the base class is Vehicle and concrete classes are TwoWheeler and FourWheeler. Now the type of the vehicle - TwoWheeler or FourWheeler, is decided by the base class Vehicle. When I create an instance of TwoWheeler/FourWheeler using alloc-init method, it calls the super implementation like below to set the value of common properties defined in the Vehicle class and out of these properties one of them is type that actually decides if the type is TwoWheeler or FourWheeler. if (self = [super initWithDictionary:dict]){ [self setOtherAttributes:dict]; return self; } Now when I get a collection of vehicles some of them could be TwoWheeler and others will be FourWheeler. Hence I cannot directly create an instance of TwoWheeler or FourWheeler like this Vehicle *v = [[TwoWheeler alloc] initWithDictionary:dict]; Is there any way I can create an instance of base class and once I know the type, create an instance of child class depending upon type and return it. With the current implementation, it would result in infinite loop because I call super implementation from concrete class. What would be the perfect design to handle this scenario when I don't know which concrete class should be instantiated beforehand?

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• Python OOP - object has no attribute

  - by user1744269

  I am attempting to learn how to program. I really do want to learn how to program; I love the building and design aspect of it. However, in Java and Python, I have tried and failed with programs as they pertain to objects, classes, methods.. I am trying to develop some code for a program, but im stumped. I know this is a simple error. However I am lost! I am hoping someone can guide me to a working program, but also help me learn (criticism is not only expected, but APPRECIATED). class Converter: def cTOf(self, numFrom): numFrom = self.numFrom numTo = (self.numFrom * (9/5)) + 32 print (str(numTo) + ' degrees Farenheit') return numTo def fTOc(self, numFrom): numFrom = self.numFrom numTo = ((numFrom - 32) * (5/9)) return numTo convert = Converter() numFrom = (float(input('Enter a number to convert.. '))) unitFrom = input('What unit would you like to convert from.. ') unitTo = input('What unit would you like to convert to.. ') if unitFrom == ('celcius'): convert.cTOf(numFrom) print(numTo) input('Please hit enter..') if unitFrom == ('farenheit'): convert.fTOc(numFrom) print(numTo) input('Please hit enter..')

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• Best strategies for reading J code

  - by estanford

  I've been using J for a few months now, and I find that reading unfamiliar code (e.g. that I didn't write myself) is one of the most challenging aspects of the language, particularly when it's in tacit. After a while, I came up with this strategy: 1) Copy the code segment into a word document 2) Take each operator from (1) and place it on a separate line, so that it reads vertically 3) Replace each operator with its verbal description in the Vocabulary page 4) Do a rough translation from J syntax into English grammar 5) Use the translation to identify conceptually related components and separate them with line breaks 6) Write a description of what each component from (5) is supposed to do, in plain English prose 7) Write a description of what the whole program is supposed to do, based on (6) 8) Write an explanation of why the code from (1) can be said to represent the design concept from (7). Although I learn a lot from this process, I find it to be rather arduous and time-consuming -- especially if someone designed their program using a concept I never encountered before. So I wonder: do other people in the J community have favorite ways to figure out obscure code? If so, what are the advantages and disadvantages of these methods?

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• Understanding Basic Prototyping & Updating Key/Value pairs

  - by JordanD

  First time poster, long time lurker. I'm trying to learn some more advanced features of .js, and have two ojectives based on the pasted code below: I would like to add methods to a parent class in a specific way (by invoking prototype). I intend to update the declared key/value pairs each time I make an associated method call. execMTAction as seen in TheSuper will execute each function call, regardless. This is by design. Here is the code: function TheSuper(){ this.options = {componentType: "UITabBar", componentName: "Visual Browser", componentMethod: "select", componentValue: null}; execMTAction(this.options.componentType, this.options.componentName, this.options.componentMethod, this.options.componentValue); }; TheSuper.prototype.tapUITextView = function(val1, val2){ this.options = {componentType: "UITextView", componentName: val1, componentMethod: "entertext", componentValue: val2}; }; I would like to execute something like this (very simple): theSuper.executeMTAction(); theSuper.tapUITextView("a", "b"); Unfortunately I am unable to overwrite the "this.options" in the parent, and the .tapUITextView method throws an error saying it cannot find executeMTAction. All I want to do, like I said, is to update the parameters in the parent, then have executeMTAction run each time I make any method call. That's it. Any thoughts? I understand this is basic but I'm coming from a long-time procedural career and .js seems to have this weird confluence of oo/procedural that I'm having a bit of difficulty with. Thanks for any input!

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• Update MySQl table onDrop?

  - by dougvt

  Hi all. I am writing a PHP/MySQL application (using CodeIgniter) that uses some jQuery functionality for dragging table rows. I have a table in which the user can drag rows to the desired order (kind of a queue for which I need to preserve the rank of each row). I've been trying to figure out how to (and whether I should) update the database each time the user drops a row, in order to simplify the UI and avoid a "Save" button. I have the jQuery working and can send a serialized list back to the server onDrop, but is it good design practice to run an update query this often? The table will usually have 30-40 rows max, but if the user drags row 1 far down the list, then potentially all the rows would need to be updated to update the rank field. I've been wondering whether to send a giant query to the server, to loop through the rows in PHP and update each row with its own Update query, to send a small serialized list to a stored procedure to let the server do all the work, or perhaps a better method I haven't considered. I've read that stored procedures in MySQL are not very efficient and use a separate process for each call. Any advice as to the right solution here? Thanks very much for your help!

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• Alert Box Methods

  - by Vecta

  I just need a little advice on what may be the best method for handling my situation. I'm in need of placing three buttons in the sidebar of the website I maintain. The website is massive and hard to handle. Currently, it's all HTML files (there are over 10,000 of them believe it or not). We're transitioning to a database website so I don't want to make any sweeping changes that are site-wide, as they may just be scrapped in our re-design process in coming months. However, these buttons are for an application process. When you click on them, an alert box will need to pop up to give you a bit of information and they either allow you to cancel the action or proceed. The buttons are currently located in the left nav which is included on every page of the website. Would it be possible to accomplish this using JS or jQuery? I'd be unable to easily add scripts into the tags on all of the applicable pages, but I'd like to avoid the browser driven "http://www...Says: blah blah" message if possible. Any insight is greatly appreciated! Thank you!

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• How to process more that one XML document in XSLT?

  - by brain_pusher

  Is there any trick to match two XML by one XSLT? I mean the way I can apply XSLT to a parameter passed. For example (I missed declarations to be short). XML1: XML to be transformed: <myData> <Collection> </Collection> </myData> XSLT need to be applied to the previous XML: <xsl:param name='items' /> <xsl:template match='Collection'> <!-- some transformation here --> </xsl:template> XML2: XML data passed as the parameter 'items': <newData> <Item>1</Item> <Item>2</Item> <Item>3</Item> </newData> And I need to create a set of nodes in the 'Collection' node in XML1 for each 'Item' element in XML2 using XSLT. And I do not know what XML2 contains exactly at design time. It is generated at runtime, so I can't place it inside XSLT, I know only its schema.

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• Is there any trick to match two XML by one XSLT?

  - by brain_pusher

  Is there any trick to match two XML by one XSLT? I mean the way I can apply XSLT to a parameter passed. For example (I missed declarations to be short). XML1: XML to be transformed: <myData> <Collection> </Collection> </myData> XSLT need to be applied to the previous XML: <xsl:param name='items' /> <xsl:template match='Collection'> <!-- some transformation here --> </xsl:template> XML2: XML data passed as the parameter 'items': <newData> <Item>1</Item> <Item>2</Item> <Item>3</Item> </newData> And I need to create a set of nodes in the 'Collection' node in XML1 for each 'Item' element in XML2 using XSLT. And I do not know what XML2 contains exactly at design time. It is generated at runtime, so I can't place it inside XSLT, I know only its schema.

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• Get height of DIV and it's content with JQuery

  - by user1012403

  I have a div which contains several elements: <div class="menuItem designMenu" id="dMenu"> <ul class="menuList menu"> <li class="menuHeader">Design</li> <li class="projectHeader">Mother</li> <li class="projectBody">Some text here</li> <li class="more">More</li> </ul> </div> I need to get the height of the dMenu items that I can animate it upwards, including all the content inside. My Javascript currently: var designHeight = $("#dMenu").height(); Returns nothing. I've tried offsetHeight, scrollHeight, and everything else Google turns up. I'm running the JQuery at the end of the body, inside a document ready function. The reason to get the height to animate, instead of doing it manually, is that a: I'd like to learn how and b: I don't yet know how many items will be int he div. Thanks.

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• Write a completely fluid HTML page (using '%' instead of 'px' for EVERY element height/width)

  - by barak manos

  I am designing my HTML pages to be completely fluid: For every element in the mark-up (HTML), I am using 'style="height:%;width:%"' (instead of 'style="height:*px;width:*px"'). This approach seems to work pretty well, except for when changing the window measurements, in which case, the web page elements change their position and end up "on top of each other". I have come up with a pretty good run-time (java-script) solution to that: var elements = document.getElementsByTagName("*"); for (var i=0; i < elements.length; i++) { if (elements[i].style.height) elements[i].style.height = elements[i].offsetHeight+"px"; if (elements[i].style.width ) elements[i].style.width = elements[i].offsetWidth +"px"; } The only problem remaining is, that if the user opens up the website by entering the URL into a non-maximized window, then the page fits that portion of the window. Then, when maximizing the window, the page remains in its previous measurements. So in essence, I have solved the initial problem (when changing the window measurements), but only when the window is initially in its maximum size. Any ideas on how to tackle this problem? (given that I would like to keep my "% page-design" as is).

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• Guidelines for creating a programming-language enjoyable to write programs in?

  - by sub

  I'm currently working on the topic of programming-languages and interpreter-design. I have already created several programming languages but couldn't reach my goal so far: Create a programming-language which focuses on giving the programmer a good feeling when writing code in it. It should just be fun and/or interesting and in no case annoying to write something in it. I get this feeling when writing code in Python. I sometimes get the opposite with PHP and in rare cases when having to reinvent some wheel in C++. So I've tried to figure out some syntactical features to make programming in my new language fun, but I just can't find any. Which concrete features, maybe mainly in terms of syntax, do/could make programming in a language fun? Examples: I find it enjoyable to program in Ruby because of it's use of code blocks. It would be nice if you could include exactly one example in your answer Those features do not have to already exist in any language! I'm doing this because I have experienced extreme rises in (my own) productivity when programming in languages I love (because of particular features).

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• jQuery removeClass(), how it works

  - by centro

  I have images on my page. User can add more images onto the page by clicking a button. New images are added asynchronously. Initially, each image on page use a special class to be used when the image is loaded. After the image is loaded, that class is removed. Each image being loaded has the class imageLoading: <img class="imageLoading" scr="someimage.png"> After those images are loaded, I remove that class (simplified code without details): $('img.imageLoading') .each(function(){ $(this) .load(function(){ $(this) .removeClass('imageloading'); });}); Visually, I see that style is removed. But when I run the query again: $('img.imageLoading') I see via debugging that all images, not just loading ones, are returned, i.e. it works like I didn't remove the class for the images that were already loaded. I had a look into the page source, and I saw that actually in HTML the class was not removed, though removeClass() was called. Is that behavior by design that all visual changes are applied but the class attribute is not removed in HTML code? If so, how it can be workarounded in this case. Or, probably, I missed something.

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• A loop (while/foreach) with "offset" wrapping and

  - by DarkGhostHunter

  After applying what wrapping objects using math operator, I just tought it will be over. But no. By far. <?php $faces= array( 1 => '<div class="block">happy</div>', 2 => '<div class="block">sad</div>', (sic) 21 => '<div class="block">angry</div>' ); $i = 1; foreach ($faces as $face) { echo $face; if ($i == 3) echo '<div class="block">This is and ad</div>'; if ($i % 3 == 0) { echo "<br />"; // or some other wrapping thing } $i++; } ?> In the code I have to put and ad after the second one, becoming by that the third object. And then wrap the three all in a <div class="row"> (a br after won't work out by design reasons). I thought I will going back to applying a switch, but if somebody put more elements in the array that the switch can properly wrap, the last two remaining elements are wrapped openly. Can i add the "ad" to the array in the third position? That would make things simplier, only leaving me with guessing how to wrap the first and the third, the fourth and the sixth, an so on.

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• include ::before pseudo class in javascript

  - by user1955837

  Why is this thing not working? If I remove ::before from javascript and css it works. But due to the design needs there has to be a ::before. How do I point to the class + ::before? $(function () { var sections = $("section"); var navigation_links = $("nav a"); sections.waypoint({ handler: function (event, direction) { var active_section; active_section = $(this); if (direction === "up") active_section = active_section.prev(); var active_link = $('nav a[href="#' + active_section.attr("id") + '"]'); navigation_links.removeClass("selected::before"); active_link.addClass("selected::before"); }, offset: '25%' }) }); css: .selected::before { display: block; content: ""; margin-top: 6px; width: 8px; height: 8px; background: url(../img/sprite.png) -126px -196px; background-size: 400px 480px; float: left; margin-left: 20px; margin-right: 20px; }

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• interface abstract in php real world scenario

  - by jason

  The goal is to learn whether to use abstract or interface or both... I'm designing a program which allows a user to de-duplicate all images but in the process rather then I just build classes I'd like to build a set of libraries that will allow me to re-use the code for other possible future purposes. In doing so I would like to learn interface vs abstract and was hoping someone could give me input into using either. Here is what the current program will do: recursive scan directory for all files determine file type is image type compare md5 checksum against all other files found and only keep the ones which are not duplicates Store total duplicates found at the end and display size taken up Copy files that are not duplicates into folder by date example Year, Month folder with filename is file creation date. While I could just create a bunch of classes I'd like to start learning more on interfaces and abstraction in php. So if I take the scan directory class as the first example I have several methods... ScanForFiles($path) FindMD5Checksum() FindAllImageTypes() getFileList() The scanForFiles could be public to allow anyone to access it and it stores in an object the entire directory list of files found and many details about them. example extension, size, filename, path, etc... The FindMD5Checksum runs against the fileList object created from scanForFiles and adds the md5 if needed. The FindAllImageTypes runs against the fileList object as well and adds if they are image types. The findmd5checksum and findallimagetypes are optionally run methods because the user might not intend to run these all the time or at all. The getFileList returns the fileList object itself. While I have a working copy I've revamped it a few times trying to figure out whether I need to go with an interface or abstract or both. I'd like to know how an expert OO developer would design it and why?

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• Storing data in XML or MongoDB

  - by user766473

  Here is my usecase. 1.Have some data, which I am storing now in the xml files. The data that I am storing is not persistent i.e I would be deleting the user data once the user logs out. 2.My server communicates with the client using the XML requests and responses. So initially we decided, since we are sending the XML as response, lets store it in XML so that conversion from database to XML format time is saved. 3.Client will request for XML based on some filter conditions. So will have to use XQUERY. 4.Maximum of 100 entries will be there in an XML, atleast as of now. Now I would like to hear some advice on whether I should use XML or mongodb. My Concerns : 1. How good is it to store temporary data in mongodb and delete/take backup once done with session 2. Conversion from mongodb json format to XML. 3. Handling the changes in the schema design. Cant use any other DB than mongodb. As some persistent operation or still done on mongodb. Thanks in advance.

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• SQL Server: Why use shorter VARCHAR(n) fields?

  - by chryss

  It is frequently advised to choose database field sizes to be as narrow as possible. I am wondering to what degree this applies to SQL Server 2005 VARCHAR columns: Storing 10-letter English words in a VARCHAR(255) field will not take up more storage than in a VARCHAR(10) field. Are there other reasons to restrict the size of VARCHAR fields to stick as closely as possible to the size of the data? I'm thinking of Performance: Is there an advantage to using a smaller n when selecting, filtering and sorting on the data? Memory, including on the application side (C++)? Style/validation: How important do you consider restricting colunm size to force non-sensical data imports to fail (such as 200-character surnames)? Anything else? Background: I help data integrators with the design of data flows into a database-backed system. They have to use an API that restricts their choice of data types. For character data, only VARCHAR(n) with n <= 255 is available; CHAR, NCHAR, NVARCHAR and TEXT are not. We're trying to lay down some "good practices" rules, and the question has come up if there is a real detriment to using VARCHAR(255) even for data where real maximum sizes will never exceed 30 bytes or so. Typical data volumes for one table are 1-10 Mio records with up to 150 attributes. Query performance (SELECT, with frequently extensive WHERE clauses) and application-side retrieval performance are paramount.

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