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• Why is using a common-lookup table to restrict the status of entity wrong?

  - by FreshCode

  According to Five Simple Database Design Errors You Should Avoid by Anith Sen, using a common-lookup table to store the possible statuses for an entity is a common mistake. Why is this wrong? I disagree that it's wrong, citing the example of jobs at a repair service with many possible statuses that generally have a natural flow, eg.: Booked In Assigned to Technician Diagnosing problem Waiting for Client Confirmation Repaired & Ready for Pickup Repaired & Couriered Irreparable & Ready for Pickup Quote Rejected Arguably, some of these statuses can be normalised to tables like Couriered Items, Completed Jobs and Quotes (with Pending/Accepted/Rejected statuses), but that feels like unnecessary schema complication. Another common example would be order statuses that restrict the status of an order, eg: Pending Completed Shipped Cancelled Refunded The status titles and descriptions are in one place for editing and are easy to scaffold as a drop-down with a foreign key for dynamic data applications. This has worked well for me in the past. If the business rules dictate the creation of a new order status, I can just add it to OrderStatus table, without rebuilding my code.

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• Can i change the view without changing the controller?

  - by Ian Boyd

  Pretend1 there is a place to type in a name:     Name: __________________ When the text box changes, the value is absorbed into the controller, who stores it in data model. Business rules require that a name be entered: if there is no text entered the TextBox should be colored something in the view to indicate baddness; otherwise it can be whatever color the view likes. The TextBox contains a String, the controller handles a String, and the model stores a String. Now lets say i want to improve the view. There is a new kind of text box2 that can be fed not only string-based keyboard input, but also an image. The view (currently) knows how to determine if the image is in the proper format to perform the processing required to extract text out of it. If there is text, then that text can be fed to the controller, who feeds it to the data model. But if the image is invalid, e.g.3 wrong file format invalid dimensions invalid bit depth unhandled or unknown encoding format missing or incorrectly located registration marks contents not recognizable the view can show something to the user that the image is bad. But the telling the user that something is bad is supposed to be the job of the controller. i'm, of course, not going to re-write the controller to handle Image based text-input (e.g. image based names). a. the code is binary locked inside a GUI widget4 b. there other views besides this one, i'm not going to impose a particular view onto the controller c. i just don't wanna. If i have to change things outside of this UI improvement, then i'll just leave the UI unimproved5 So what's the thinking on having different views for the same Model and Controller? Nitpicker's Corner 1 contrived hypothetical example 2 e.g. bar code, g-mask, ocr 3 contrived hypothetical reasons 4 or hardware of a USB bar-code scanner 5 forcing the user to continue to use a DateTimePicker rather than a TextBox

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• What is the appropriate way to set a VB StringBuilder to an empty string?

  - by Wayne Werner

  I'm using VB's StringBuilder, and I was curious what is considered "best practice" for emptying the builder/setting it to a new string. Would it be something like this: Dim str As New System.Text.StringBuilder() str.Append("Some string to remove") str = new System.Text.StringBuilder() str.Append("Ahh, fresh new text!") or is there a "Better" way? Thanks

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• SQL exclude a column using SELECT * [except columnA] FROM tableA?

  - by uu?????s

  We all know that to select all columns from a table, we can use SELECT * FROM tableA Is there a way to exclude column(s) from a table without specifying all the columns? SELECT * [except columnA] FROM tableA The only way that I know is to manually specify all the columns and exclude the unwanted column. This is really time consuming so I'm looking for ways to save time and effort on this, as well as future maintenance should the table has more/less columns. thanks!

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• Observer pattern and violation of Single Responsibility Principle

  - by Devil Jin

  I have an applet which repaints itself once the text has changed Design 1: //MyApplet.java public class MyApplet extends Applet implements Listener{ private DynamicText text = null; public void init(){ text = new DynamicText("Welcome"); } public void paint(Graphics g){ g.drawString(text.getText(), 50, 30); } //implement Listener update() method public void update(){ repaint(); } } //DynamicText.java public class DynamicText implements Publisher{ // implements Publisher interface methods //notify listeners whenever text changes } Isn't this a violation of Single Responsibility Principle where my Applet not only acts as Applet but also has to do Listener job. Same way DynamicText class not only generates the dynamic text but updates the registered listeners. Design 2: //MyApplet.java public class MyApplet extends Applet{ private AppletListener appLstnr = null; public void init(){ appLstnr = new AppletListener(this); // applet stuff } } // AppletListener.java public class AppletListener implements Listener{ private Applet applet = null; public AppletListener(Applet applet){ this.applet = applet; } public void update(){ this.applet.repaint(); } } // DynamicText public class DynamicText{ private TextPublisher textPblshr = null; public DynamicText(TextPublisher txtPblshr){ this.textPblshr = txtPblshr; } // call textPblshr.notifyListeners whenever text changes } public class TextPublisher implments Publisher{ // implements publisher interface methods } Q1. Is design 1 a SPR violation? Q2. Is composition a better choice here to remove SPR violation as in design 2.

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• Best way to unit test Collection?

  - by limc

  I'm just wondering how folks unit test and assert that the "expected" collection is the same/similar as the "actual" collection (order is not important). To perform this assertion, I wrote my simple assert API:- public void assertCollection(Collection<?> expectedCollection, Collection<?> actualCollection) { assertNotNull(expectedCollection); assertNotNull(actualCollection); assertEquals(expectedCollection.size(), actualCollection.size()); assertTrue(expectedCollection.containsAll(actualCollection)); assertTrue(actualCollection.containsAll(expectedCollection)); } Well, it works. It's pretty simple if I'm asserting just bunch of Integers or Strings. It can also be pretty painful if I'm trying to assert a collection of Hibernate domains, say for example. The collection.containsAll(..) relies on the equals(..) to perform the check, but I always override the equals(..) in my Hibernate domains to check only the business keys (which is the best practice stated in the Hibernate website) and not all the fields of that domain. Sure, it makes sense to check just against the business keys, but there are times I really want to make sure all the fields are correct, not just the business keys (for example, new data entry record). So, in this case, I can't mess around with the domain.equals(..) and it almost seems like I need to implement some comparators for just unit testing purposes instead of relying on collection.containsAll(..). Are there some testing libraries I could leverage here? How do you test your collection? Thanks.

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• what's wrong in File.Exist() method?

  - by Arseny

  Reading some answers with code samples I notice that those where this method mentioned are subjected to criticism. I'm using this method in my code. So I'd like to know if someone give me detailed response whuy this method is not recomemnded and what alternative approaches are?

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• Is there any diff between these two "if" conditional statement?

  - by Pandiya Chendur

  First if condition if(Txt1.Text != "" && Txt2.Text != "") Second if condition if((Txt1.Text && Txt2.Text) != "") Is there any diff between these two conditional statement?

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• Partial class or "chained inheritance"

  - by Charlie boy

  Hi From my understanding partial classes are a bit frowned upon by professional developers, but I've come over a bit of an issue; I have made an implementation of the RichTextBox control that uses user32.dll calls for faster editing of large texts. That results in quite a bit of code. Then I added spellchecking capabilities to the control, this was made in another class inheriting RichTextBox control as well. That also makes up a bit of code. These two functionalities are quite separate but I would like them to be merged so that I can drop one control on my form that has both fast editing capabilities and spellchecking built in. I feel that simply adding the code form one class to the other would result in a too large code file, especially since there are two very distinct areas of functionality, so I seem to need another approach. Now to my question; To merge these two classes should I make the spellchecking RichTextBox inherit from the fast edit one, that in turn inherits RichTextBox? Or should I make the two classes partials of a single class and thus making them more “equal” so to speak? This is more of a question of OO principles and exercise on my part than me trying to reinvent the wheel, I know there are plenty of good text editing controls out there. But this is just a hobby for me and I just want to know how this kind of solution would be managed by a professional. Thanks!

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• DOs and DON'Ts of a technical presentation

  - by TG

  I am preparing a technical presentation for my team. Audience : Our team Topic : Introduction to a new technology So I want to know about the primary necessary things for a good technical presentation and also DOs and DON'Ts for the same. some of my concerns are, 1. Whether to have slides or not (if needed then how many of them) 2. Coding a sample during presentation or preparing it before going for the presentation 3. Maximum duration of an technical presentation What is your thoughts on technical presentations from your past experience either as a presenter or as a listener.

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• UX Design Question: Should a multi step wizard save the form contents when the user clicks 'go back'

  - by Ashwin Prabhu

  I am developing a web application that collects data over multiple steps through a wizard. Steps are generally not interdependent, in that data input at each step has little or no effect on the consequent steps. However each step may have a set of validations which determine whether the user can progress to the next step by clicking 'continue' What should be the behavior when the user clicks previous? a Quickly move to the previous page, thus losing all the unsaved data in the form. Prompting the user with a warning is an option, but it can become irritating quite soon. b Move to the previous page saving all the data in the current step - without triggering validations, so that when the user comes back she sees the form in the same state that she left it in. c any other behaviour All opinions are welcome :)

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• True or False: Good design calls for every table to have a primary key, if nothing else, a running i

  - by Velika

  Consider a grocery store scenario (I'm making this up) where you have FACT records that represent a sale transaction, where the columns of the Fact table include SaleItemFact Table ------------------ CustomerID ProductID Price DistributorID DateOfSale Etc Etc Etc Even if there are duplicates in the table when you consider ALL the keys, I would contend that a surrogate running numeric key (i.e. identity column) should be made up, e.g., TransactionNumber of type Integer. I can see someone arguing that a Fact table might not have a unique key (though I'd invent one and waste the 4 bytes, but how about a dimension table?

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• Is this 2D array initialization a bad idea?

  - by Brendan Long

  I have something I need a 2D array for, but for better cache performance, I'd rather have it actually be a normal array. Here's the idea I had but I don't know if it's a terrible idea: const int XWIDTH = 10, YWIDTH = 10; int main(){ int * tempInts = new int[XWIDTH * YWIDTH]; int ** ints = new int*[XWIDTH]; for(int i=0; i<XWIDTH; i++){ ints[i] = &tempInts[i*YWIDTH]; } // do things with ints delete[] ints[0]; delete[] ints; return 0; } So the idea is that instead of newing a bunch of arrays (and having them placed in different places in memory), I just point to an array I made all at once. The reason for the delete[] (int*) ints; is because I'm actually doing this in a class and it would save [trivial amounts of] memory to not save the original pointer. Just wondering if there's any reasons this is a horrible idea. Or if there's an easier/better way. The goal is to be able to access the array as ints[x][y] rather than ints[x*YWIDTH+y].

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• Why is database view used?

  - by Sessiz Saat

  Is using "view" in db design right method or we should handle it code side? What are the advantages or disadvantages?

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• Why should I use core.autocrlf in Git

  - by Rich

  I have a Git repository that is accessed from both Windows and OS X, and that I know already contains some files with CRLF line-endings. As far as I can tell, there are two ways to deal with this: Set core.autocrlf to false everywhere, Follow the instructions here (echoed on GitHub's help pages) to convert the repository to contain only LF line-endings, and thereafter set core.autocrlf to true on Windows and input on OS X. The problem with doing this is that if I have any binary files in the repository that: a). are not correctly marked as binary in gitattributes, and b). happen to contain both CRLFs and LFs, they will be corrupted. It is possible my repository contains such files. So why shouldn't I just turn off Git's line-ending conversion? There are a lot of vague warnings on the web about having core.autocrlf switched off causing problems, but very few specific ones; the only that I've found so far are that kdiff3 cannot handle CRLF endings (not a problem for me), and that some text editors have line-ending issues (also not a problem for me). The repository is internal to my company, and so I don't need to worry about sharing it with people with different autocrlf settings or line-ending requirements. Are there any other problems with just leaving line-endings as-is that I am unaware of?

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• I don't like Python functions that take two or more iterables. Is it a good idea?

  - by Xavier Ho

  This question came from looking at this question on Stackoverflow. def fringe8((px, py), (x1, y1, x2, y2)): Personally, it's been one of my pet peeves to see a function that takes two arguments with fixed-number iterables (like a tuple) or two or more dictionaries (Like in the Shotgun API). It's just hard to use, because of all the verbosity and double-bracketed enclosures. Wouldn't this be better: >>> class Point(object): ... def __init__(self, x, y): ... self.x = x ... self.y = y ... >>> class Rect(object): ... def __init__(self, x1, y1, x2, y2): ... self.x1 = x1 ... self.y1 = y1 ... self.x2 = x2 ... self.y2 = y2 ... >>> def fringe8(point, rect): ... # ... ... >>> >>> point = Point(2, 2) >>> rect = Rect(1, 1, 3, 3) >>> >>> fringe8(point, rect) Is there a situation where taking two or more iterable arguments is justified? Obviously the standard itertools Python library needs that, but I can't see it being pretty in maintainable, flexible code design.

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• What are the 'big' advantages to have Poco with ORM?

  - by bonefisher

  One advantage that comes to my mind is, if you use Poco classes for Orm mapping, you can easily switch from one ORM to another, if both support Poco. Having an ORM with no Poco support, e.g. mappings are done with attributes like the DataObjects.Net Orm, is not an issue for me, as also with Poco-supported Orms and theirs generated proxy entities, you have to be aware that entities are actually DAO objects bound to some context/session, e.g. serializing is a problem, etc..

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• jQuery: Stopping a periodic ajax call?

  - by Legend

  I am writing a small jQuery plugin to update a set of Divs with content obtained using Ajax calls. Initially, let's assume we have 4 divs. I am doing something like this: (function($) { .... .... //main function $.fn.jDIV = { init: function() { ... ... for(var i = 0; i < numDivs; i++) { this.query(i); } this.handlers(); }, query: function(divNum) { //Makes the relevant ajax call }, handlers: function() { for(var i = 0; i < numDivs; i++) { setInterval("$.fn.jDIV.query(" + i + ")", 5000); } } }; })(jQuery); I would like to be able to enable and disable a particular ajax query. I was thinking of adding a "start" and "stop" instead of the "handlers" function and subsequently storing the setInterval handler like this: start: function(divNum) { divs[divNum] = setInterval("$.fn.jDIV.query(" + i + ")", 5000); }, stop: function(divNum) { clearInterval(divs[divNum]); } I did not use jQuery to setup and destroy the event handlers. Is there a better approach (perhaps using more of jQuery) to achieve this?

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• How does the verbosity of identifiers affect the performance of a programmer?

  - by DR

  I always wondered: Are there any hard facts which would indicate that either shorter or longer identifiers are better? Example: clrscr() opposed to ClearScreen() Short identifiers should be faster to read because there are fewer characters but longer identifiers often better resemble natural language and therefore also should be faster to read. Are there other aspects which suggest either a short or a verbose style? EDIT: Just to clarify: I didn't ask: "What would you do in this case?". I asked for reasons to prefer one over the other, i.e. this is not a poll question. Please, if you can, add some reason on why one would prefer one style over the other.

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• What are some good usability guidelines an average developer should follow?

  - by Allain Lalonde

  I'm not a usability specialist, and I really don't care to be one. I just want a small set of rules of thumb that I can follow while coding my User Interfaces so that my product has decent usability. At first I thought that this question would be easy to answer "Use your common sense", but if it's so common among us developers we wouldn't, as a group, have a reputation for our horrible interfaces. Any Suggestions?

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• must have tools for better quality code

  - by leon

  I just started my real development career and I want to know what set of tools/strategy that the community is using to write better quality code. To start, I use astyle to format my code doxygen to document my code gcc -Wall -Wextra -pedantic and clang -Wall -Wextra -pedantic to check all warnings What tools/strategy do you use to write better code? This question is open to all language and all platform.

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• Multiple asserts in single test?

  - by Gern Blandston

  Let's say I want to write a function that validates an email address with a regex. I write a little test to check my function and write the actual function. Make it pass. However, I can come up with a bunch of different ways to test the same function ([email protected]; [email protected]; test.test.com, etc). Do I put all the incantations that I need to check in the same, single test with several ASSERTS or do I write a new test for every single thing I can think of? Thanks!

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• What are the principles of developing web-applications with action-based java frameworks?

  - by Roman

  Background I'm going to develop a new web-application with java. It's not very big or very complex and I have enough time until it'll "officially" start. I have some JSF/Facelets development background (about half a year). And I also have some expirience with JSP+JSTL. In self-educational purpose (and also in order to find the best solution) I want to prototype the new project with one of action-based frameworks. Actually, I will choose between Spring MVC and Stripes. Problem In order to get correct impression about action-based frameworks (in comparison with JSF) I want to be sure that I use them correctly (in bigger or lesser extent). So, here I list some most-frequent tasks (at least for me) and describe how I solve them with JSF. I want to know how they should be solved with action-based framework (or separately with Spring MVC and Stripes if there is any difference for concrete task). Rendering content: I can apply ready-to-use component from standard jsf libraries (core and html) or from 3rd-party libs (like RichFaces). I can combine simple components and I can easily create my own components which are based on standard components. Rendering data (primitive or reference types) in the correct format: Each component allow to specify a converter for transforming data in both ways (to render and to send to the server). Converter is, as usual, a simple class with 2 small methods. Site navigation: I specify a set of navigation-cases in faces-config.xml. Then I specify action-attribute of a link (or a button) which should match one or more of navigation cases. The best match is choosen by JSF. Implementing flow (multiform wizards for example): I'm using JSF 1.2 so I use Apache Orchestra for the flow (conversation) scope. Form processing: I have a pretty standard java-bean (backing bean in JSF terms) with some scope. I 'map' form fields on this bean properties. If everything goes well (no exceptions and validation is passed) then all these properties are set with values from the form fields. Then I can call one method (specified in button's action attribute) to execute some logic and return string which should much one of my navigation cases to go to the next screen. Forms validation: I can create custom validator (or choose from existing) and add it to almost each component. 3rd-party libraries have sets of custom ajax-validators. Standard validators work only after page is submitted. Actually, I don't like how validation in JSF works. Too much magic there. Many standard components (or maybe all of them) have predefined validation and it's impossible to disable it (Maybe not always, but I met many problems with it). Ajax support: many 3rd-party libraries (MyFaces, IceFaces, OpenFaces, AnotherPrefixFaces...) have strong ajax support and it works pretty well. Until you meet a problem. Too much magic there as well. It's very difficult to make it work if it doesn't work but you've done right as it's described in the manual. User-friendly URLs: people say that there are some libraries for that exist. And it can be done with filters as well. But I've never tried. It seems too complex for the first look. Thanks in advance for explaning how these items (or some of them) can be done with action-based framework.

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• Doing a ajax / json add to database, and have a "wait doing operation" icon

  - by Dejan.S

  Hi. I got a part on my page I want to improve. It's a file upload that users can add their contacts from files like excel, csv & outlook. I read the contacts and place them in the database, so what I would like to do is to have a regular icon that spins while that operation is doing that, how could I do that? Ajax? I don't want progress bar for the file upload but the operation for reading the file EDIT: I want to know how to make this work with the add to database using ajax. like should I use a updatepanel? Thanks

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• Why people do not like OOP? [closed]

  - by Gabriel Šcerbák

  I do not understand why people choose C++ over Smalltalk in past and why Java over Python or Ruby. What is it that ties people so much to the procedural programming and makes it so difficult to go "all the way" to object oriented programming? What makes OOP hard? Should not objects be an abstraction which is easier to grasp for people, i.e. a more natural one than procedures? Is education the problem (because people tend to learn procedural programming before object oriented)?

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