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  • best practices - multiple functions vs single function with switch case

    - by Amit
    I have a situation where I need to perform several small (but similar) tasks. I can think of two ways to achieve this. First Approach: function doTask1(); function doTask2(); function doTask3(); function doTask4(); Second Approach: // TASK1, TASK2, ... TASK4 are all constants function doTask(TASK) { switch(TASK) { case TASK1: // do task1 break; case TASK2: // do task2 break; case TASK3: // do task3 break; case TASK4: // do task4 break; } } A few more tasks may be added in future (though the chances are rare. but this cannot be ruled out) Please suggest which of the two approaches (or if any other) is a best practice in such a situation.

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  • Historical / auditable database

    - by Mark
    Hi all, This question is related to the schema that can be found in one of my other questions here. Basically in my database I store users, locations, sensors amongst other things. All of these things are editable in the system by users, and deletable. However - when an item is edited or deleted I need to store the old data; I need to be able to see what the data was before the change. There are also non-editable items in the database, such as "readings". They are more of a log really. Readings are logged against sensors, because its the reading for a particular sensor. If I generate a report of readings, I need to be able to see what the attributes for a location or sensor was at the time of the reading. Basically I should be able to reconstruct the data for any point in time. Now, I've done this before and got it working well by adding the following columns to each editable table: valid_from valid_to edited_by If valid_to = 9999-12-31 23:59:59 then that's the current record. If valid_to equals valid_from, then the record is deleted. However, I was never happy with the triggers I needed to use to enforce foreign key consistency. I can possibly avoid triggers by using the extension to the "PostgreSQL" database. This provides a column type called "period" which allows you to store a period of time between two dates, and then allows you to do CHECK constraints to prevent overlapping periods. That might be an answer. I am wondering though if there is another way. I've seen people mention using special historical tables, but I don't really like the thought of maintainling 2 tables for almost every 1 table (though it still might be a possibility). Maybe I could cut down my initial implementation to not bother checking the consistency of records that aren't "current" - i.e. only bother to check constraints on records where the valid_to is 9999-12-31 23:59:59. Afterall, the people who use historical tables do not seem to have constraint checks on those tables (for the same reason, you'd need triggers). Does anyone have any thoughts about this? PS - the title also mentions auditable database. In the previous system I mentioned, there is always the edited_by field. This allowed all changes to be tracked so we could always see who changed a record. Not sure how much difference that might make. Thanks.

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  • Producer/consumer in Grails?

    - by Mulone
    Hi all, I'm trying to implement a Consumer/Producer app in Grails, after several unsuccessful attempts at implementing concurrent threads. Basically I want to store all the events coming from a clients (through separate AJAX calls) in a single queue and then process such a queue in a linear way as soon as new events are added. This looks like a Producer/Consumer problem: http://en.wikipedia.org/wiki/Producer-consumer_problem How can I implement this in Grails (maybe with a timer or even better by generating an event 'process queue')? Basically I'd like to a have a singleton service waiting for new events in the queue and processing them linearly (even if the queue is loaded by several concurrent processes). Any hints? Cheers!

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  • Unit of Work Pattern in .Net

    - by Jazza
    Does anyone have any concrete examples of a simple Unit of Work pattern in C# or Visual Basic that would handle the following scenario? I'm writing a WinForms application in which a customer can have multiple addresses associated with it. The user can add, edit and delete addresses belonging to the customer before the customer is saved back to the database. Therefore, at the time of saving, all the original addresses need to be deleted from the database and the new addresses added in a single transaction.

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  • In .NET, Why Can I Access Private Members of a Class Instance within the Class?

    - by AMissico
    While cleaning some code today written by someone else, I changed the access modifier from Public to Private on a class variable/member/field. I expected a long list of compiler errors that I use to "refactor/rework/review" the code that used this variable. Imagine my surprise when I didn't get any errors. After reviewing, it turns out that another instance of the Class can access the private members of another instance declared within the Class. Totally unexcepted. Is this normal? I been coding in .NET since the beginning and never ran into this issue, nor read about it. I may have stumbled onto it before, but only "vaguely noticed" and move on. Can anyone explain this behavoir to me? I would like to know the "why" I can do this. Please explain, don't just tell me the rule. Am I doing something wrong? I found this behavior in both C# and VB.NET. The code seems to take advantage of the ability to access private variables. Sincerely, Totally Confused Class Jack Private _int As Integer End Class Class Foo Public Property Value() As Integer Get Return _int End Get Set(ByVal value As Integer) _int = value * 2 End Set End Property Private _int As Integer Private _foo As Foo Private _jack As Jack Private _fred As Fred Public Sub SetPrivate() _foo = New Foo _foo.Value = 4 'what you would expect to do because _int is private _foo._int = 3 'TOTALLY UNEXPECTED _jack = New Jack '_jack._int = 3 'expected compile error _fred = New Fred '_fred._int = 3 'expected compile error End Sub Private Class Fred Private _int As Integer End Class End Class

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  • Is there a way of using one method to handle others to avoid code duplication?

    - by Artur
    I wonder if there is a way of writing a method or a class that would add to any method some code that is shared between many methods. The methods return different things and some of them are just void. Below is a part of the code that is duplicated in the methods. StartTimer(MethodBase.GetCurrentMethod().Name); try { // Actual method body } catch (Exception ex) { bool rethrow = ExceptionPolicy.HandleException(ex, "DALPolicy"); if (rethrow) { throw; } } finally { StopTimer(MethodBase.GetCurrentMethod().Name); } Any help would be greatly appreciated.

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  • How to create a "facade" table?

    - by tputkonen
    A legacy database contains a join table which links tables table1 and table2, and contains just two foreign keys: TABLE_ORIG: table1_id table2_id In order to utilize this table using JPA I would need to create a surrogate primary key to the link table. However, the existing table must not be modified at all. I would like to create another table which would contain also a primary key in addition to the foreign keys: TABLE_NEW: id table1_id table2_id All changes to TABLE_ORIG should be reflected in TABLE_NEW, and vice versa. Is this doable in mysql?

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  • Need an ASP.NET MVC long running process with user feedback

    - by Jason
    I've been trying to create a controller in my project for delivering what could turn out to be quite complex reports. As a result they can take a relatively long time and a progress bar would certainly help users to know that things are progressing. The report will be kicked off via an AJAX request, with the idea being that periodic JSON requests will get the status and update the progress bar. I've been experimenting with the AsyncController as that seems to be a nice way of running long processes without tying up resources, but it doesn't appear to give me any way of checking on the progress (and seems to block further JSON requests and I haven't discovered why yet). After that I've tried resorting to storing progress in a static variable on the controller and reading the status from that - but to be honest that all seems a bit hacky! All suggestions gratefully accepted!

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  • Is Multiple Iterators is possible in php?

    - by artvolk
    Good day! I know that C# allows multiple iterators using yield, like described here: http://stackoverflow.com/questions/1754041/is-multiple-iterators-is-possible-in-c In PHP there is and Iterator interface. Is it possible to implement more than one iteration scenario for a class?

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  • Using OpenGL drawing operations in an object-oriented setting?

    - by Lion Kabob
    I've been plowing through basic shaders and whatnot for an application I'm writing, and I've been having trouble figuring out a high-level organization for the drawing calls. I'm thinking of having a singleton class which implements a number of basic drawing operations, taking data from "user" classes and passing that to the appropriate opengl calls. I'm wondering how people do this when writing their own applications, as the internet is chock full of basic "Your first shader" tutorials, but very little on suggested organization of drawing code. My particular environment is targeted at iPad/OpenGL ES 2.0, but I think the question stands for most environments.

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  • CSS for top right corner of the page

    - by user102533
    How would I have a top right corner div as shown in the image. I want to do something similar though not exactly the same. I think the text is not an image. Also, I have seen some websites that has a page hover effect when a mouse is over the top right section. Any idea how to do that?

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  • Efficient algorithm for creating an ideal distribution of groups into containers?

    - by Inshim
    I have groups of students that need to be allocated into classrooms of a fixed capacity (say, 100 chairs in each). Each group must only be allocated to a single classroom, even if it is larger than the capacity (ie there can be an overflow, with students standing up) I need an algorithm to make the allocations with minimum overflows and under-capacity classrooms. A naive algorithm to do this allocation is horrendously slow when having ~200 groups, with a distribution of about half of them being under 20% of the classroom size. Any ideas where I can find at least some good starting point for making this algorithm lightning fast? Thanks!

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  • Factory Method Pattern using Generics-C#

    - by nanda
    Just I am learning Generics.When i have an Abstract Method pattern like : //Abstract Product interface IPage { string pageType(); } //Concerete Product 1 class ResumePage : IPage { public string pageType() { return "Resume Page"; } } //Concrete Product 2 class SummaryPage : IPage { public string pageType() { return "SummaryPage"; } } //Fcatory Creator class FactoryCreator { public IPage CreateOnRequirement(int i) { if (i == 1) return new ResumePage(); else { return new SummaryPage(); } } } //Client/Consumer void Main() { FactoryCreator c = new FactoryCreator(); IPage p; p = c.CreateOnRequirement(1); Console.WriteLine("Page Type is {0}", p.pageType()); p = c.CreateOnRequirement(2); Console.WriteLine("Page Type is {0}", p.pageType()); Console.ReadLine(); } how to convert the code using generics?

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  • Using implicit conversion as a substitute for multiple inheritance in .NET

    - by Daniel Plaisted
    I have a situation where I would like to have objects of a certain type be able to be used as two different types. If one of the "base" types was an interface this wouldn't be an issue, but in my case it is preferable that they both be concrete types. I am considering adding copies of the methods and properties of one of the base types to the derived type, and adding an implicit conversion from the derived type to that base type. Then users will be able treat the derived type as the base type by using the duplicated methods directly, by assigning it to a variable of the base type, or by passing it to a method that takes the base type. It seems like this solution will fit my needs well, but am I missing anything? Is there a situation where this won't work, or where it is likely to add confusion instead of simplicity when using the API?

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  • How do i make my text wrap in a <div> with a large border radius

    - by Greg Guida
    in the following code <html> <body> <div style="height:400px; width:400px; -moz-border-radius:100px; -webkit-border-radius:100px; border:3px solid #500; background-color:#a00; overflow:hidden;"> Why is this getting cut at the beginning??? </div> </body> </html> Why isn't the browser wrapping the text around the rounded corners. In webkit browsers(i tested both chrome and safari) the overflow hidden cuts the text outside the border. Firefox just renders text outside the border. I also tried this without overflow:hidden; but again the text just rendered outside the border.

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  • Are there any online database schema drawing tools?

    - by Pure.Krome
    Hi folks, i wish to draw up some database schemas. Eg, table 1 has zero to many rows in table 2, etc. It's purely for visual purposes (eg. no sql code, etc). Are there any online tools / website that offer this? (please don't say: Use Sql Server Database Diagrams, print screen, upload to image hosting service). thanks :) EDIT: Please take note of the keyword - ONLINE. I don't want any desktop solutions (because I already have one of these).

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  • Performance Tricks for C# Logging

    - by Charles
    I am looking into C# logging and I do not want my log messages to spend any time processing if the message is below the logging threshold. The best I can see log4net does is a threshold check AFTER evaluating the log parameters. Example: _logger.Debug( "My complicated log message " + thisFunctionTakesALongTime() + " will take a long time" ) Even if the threshold is above Debug, thisFunctionTakesALongTime will still be evaluated. In log4net you are supposed to use _logger.isDebugEnabled so you end up with if( _logger.isDebugEnabled ) _logger.Debug( "Much faster" ) I want to know if there is a better solution for .net logging that does not involve a check each time I want to log. In C++ I am allowed to do LOG_DEBUG( "My complicated log message " + thisFunctionTakesALongTime() + " will take no time" ) since my LOG_DEBUG macro does the log level check itself. This frees me to have a 1 line log message throughout my app which I greatly prefer. Anyone know of a way to replicate this behavior in C#?

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  • Factory Pattern: Determining concrete factory class instantiation?

    - by Chris
    I'm trying to learn patterns and I'm stuck on determining how or where a Factory Pattern determines what class to instanciate. If I have a Application that calls the factory and sends it, say, an xml config file to determine what type of action to take, where does that logic for interpreting the config file happen? THE FACTORY using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace myNamespace { public abstract class SourceFactory { abstract public UploadSource getUploadSource(); } public class TextSourceFactory : SourceFactory { public override UploadSource getUploadSource() { return new TextUploadSource(); } } public class XmlSourceFacotry : SourceFactory { public override UploadSource getUploadSource() { return new XmlUploadSource(); } } public class SqlSourceFactory : SourceFactory { public override UploadSource getUploadSource() { return new SqlUploadSource(); } } } THE CLASSES using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace myNamespace { public abstract class UploadSource { abstract public void Execute(); } public class TextUploadSource : UploadSource { public override void Execute() { Console.WriteLine("You executed a text upload source"); } } public class XmlUploadSource : UploadSource { public override void Execute() { Console.WriteLine("You executed an XML upload source"); } } public class SqlUploadSource : UploadSource { public override void Execute() { Console.WriteLine("You executed a SQL upload source"); } } }

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  • Is it immoral to write crappy code even if readability and correctness is not a requirement?

    - by mafutrct
    There are cases when crappy (i.e. unreadable and buggy) code is not much of a problem. For instance, imagine you need to generate a big text file that mostly follows a simple pattern with a few very complex exceptions. What do you do? You quickly write a simple algorithm and insert the exceptional bits in the output manually to save 4 hours. The code is unreadable, and the output is flawed, but it's still the correct way since it is way faster. But let's get this straight: I hate bad code. I've had to read and work with code that caused my stomach to hurt. I care a lot about good code. And actually, I caught myself thinking that it is immoral to write bad code even though the dirty approach is sometimes superior. I was surprised by myself and found my idea to be very irrational. Did you ever experience this? Should I just get rid of this stupid idea and use the most efficient approach to coding?

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