.NET (Core and Framework)

19-Jan-09 14:23

I'm trying to piece together someone else's code. The code was looking for Oracle.DataAccess.DLL for Oracle 10. My GAC has version 9.2.0.700, so I downloaded the dll for version 10, copied it to the \bin\Debug directory and added a reference using the BROWSE tab. When I try to build, however, I get this:

D:\Projects\Gnf.Utils_Source\Gnf.Utils.Oracle\Database.cs(5,18): error CS0234: The type or namespace name 'DataAccess' does not exist in the namespace 'Gnf.Utils.Oracle' (are you missing an assembly reference?)

My output appears to say that my intended version was picked up:

Primary reference "Oracle.DataAccess, Version=10.1.0.400, Culture=neutral, PublicKeyToken=89b483f429c47342".
Resolved file path is "bin\Debug\Oracle.DataAccess.dll".
Reference found at search path location "bin\Debug\".

When I double click on the reference it shows the namespace as :

namespace Oracle.DataAccess.Client
Member of Oracle.DataAccess

In my code I have this

namespace Gnf.Utils.Oracle
{
using Oracle.DataAccess.Client;

It just doesn't seem that it's recognizing that reference. I've tried to use the version 9.2 from the GAC. I've tried creating a new project. I'm not sure what else to look at. I'm very confused.

Eddy Vluggen20-Jan-09 3:19

Eddy Vluggen

20-Jan-09 3:19

What about this?

namespace Gnf.Utils.Oracle
{
    using Oracle.DataAccess;

I are troll Smile | :)

OldSchoolToC#20-Jan-09 7:54

20-Jan-09 7:54

Thanks for the suggestion, but it didn't work. In fact, the intellisense doesn't kick in at all when I type the "Oracle.".

Wendelius20-Jan-09 9:13

20-Jan-09 9:13

You could check that the Specific Version property is not set to true for your reference. If it is, perhaps it could cause the problem.

The need to optimize rises from a bad design.My articles[^]

OldSchoolToC#20-Jan-09 9:29

20-Jan-09 9:29

I tried to build using your suggestion to set SPECIFIC VERSION to FALSE, but it still failed.

Wendelius20-Jan-09 9:42

20-Jan-09 9:42

Wait a second... Are the lines in correct order? Shouldn't it be:

using Oracle.DataAccess.Client;
namespace Gnf.Utils.Oracle
{
...

The need to optimize rises from a bad design.My articles[^]

OldSchoolToC#20-Jan-09 9:48

20-Jan-09 9:48

Yes!!!! That worked! But I don't understand.

I didn't change that code at all, and I'm sure the previous developer built it successfully.

I don't understand why I have to declare this particular thing outside of the namespace, while the others can be defined inside.

using Oracle.DataAccess.Client;

namespace Gnf.Utils.Oracle
{
using Gnf.Utils.Data;
using System;
using System.Collections.Generic;
using System.Data;
using System.Runtime.InteropServices;
using System.Threading;

Wendelius20-Jan-09 9:56

20-Jan-09 9:56

I'm not sure. Perhaps you have two namespaces in the file and if the the other one also wants to use classes from Oracle.DataAccess.Client, the using directive would be out of scope, just a guess since I actually never use using directive. I always like to add full namespace to a class definition.

The need to optimize rises from a bad design.My articles[^]

Member 362614020-Jan-09 11:02

Member 3626140

20-Jan-09 11:02

Well, its a standard practice to use Using before declaring Namespace.

The compiler need to know what references to use (Using) before it can compile the namespace function map.

Wendelius20-Jan-09 11:08

visual studio thinks it resides in Europe, and we're actually in the US

20-Jan-09 11:08

Yes, it's very common to use it before namespace, but not mandatory: http://msdn.microsoft.com/en-us/library/sf0df423.aspx[^]

The need to optimize rises from a bad design.My articles[^]

Mihai Pruna19-Jan-09 14:00

Mihai Pruna

19-Jan-09 14:00

So I'm coding in .NET (C#), under Visual Studio, and getting some numbers in string format and converting them to double.Parse to doubles. However, it only works if the number strings first have the . replaced with a ,
How can I make the double.parse command give me decimals delimited with dots , not commas?

Codes for Scientists and Engineers

Re: visual studio thinks it resides in Europe, and we're actually in the US

Not Active19-Jan-09 15:32

Not Active

19-Jan-09 15:32

Have you checked setting for the local computer? In Vista the formatting is set in the Regional and Language options dialog from the control panel

only two letters away from being an asset

Re: visual studio thinks it resides in Europe, and we're actually in the US

Mihai Pruna20-Jan-09 2:57

Mihai Pruna

20-Jan-09 2:57

Thanks, good idea, however, I just checked and the decimal separator is already defined as the dot.

Codes for Scientists and Engineers

Re: visual studio thinks it resides in Europe, and we're actually in the US

omlac20-Jan-09 3:16

omlac

20-Jan-09 3:16

use this:
double dummyOut = new double();
System.Globalization.CultureInfo cultureInfo = new System.Globalization.CultureInfo("en-US", true);
Double.TryParse(anyString, System.Globalization.NumberStyles.Any, cultureInfo.NumberFormat, out dummyOut); }

Does the use of many trivial classes with generics pose a performance penalty?

supercat919-Jan-09 10:00

supercat9

19-Jan-09 10:00

Using generics and interfaces in .net, it's possible to design a class so that a particular method name can invoke a number of different methods, based upon the type of a passed-in parameter. For example:

Class DoItMagic
    Interface iAct(Of T)
        Sub Act(ByVal param As T)
    End Interface

    Public Shared Sub exec(Of T)(ByVal target As iAct(Of T), ByVal param As T)
        target.Act(param)
    End Sub

    Public Shared Sub hitEverything(Of T, U As DoItMagic.iAct(Of T))(ByVal theEnum As IEnumerable(Of U), ByVal theParam As T)
        For Each thing As U In theEnum
            exec(Of T)(thing, theParam)
        Next
    End Sub
End Class

Class DoItTarget
    Implements DoItMagic.iAct(Of param1), DoItMagic.iAct(Of param2)

    Class param1
    End Class

    Class param2
    End Class

    Public Sub Act_param1(ByVal param As param1) Implements DoItMagic.iAct(Of param1).Act

    End Sub

    Public Sub Act_param2(ByVal param As param2) Implements DoItMagic.iAct(Of param2).Act

    End Sub
End Class

Class DoItTest
    Dim firstParam As DoItTarget.param1
    Dim secondParam As DoItTarget.param2

    Dim L As List(Of DoItTarget)

    Sub go()
        DoItMagic.hitEverything(Of DoItTarget.param1, DoItTarget)(L, firstParam)
        DoItMagic.hitEverything(Of DoItTarget.param2, DoItTarget)(L, secondParam)
    End Sub
End Class

This approach seems to work out pretty elegantly. The first hitEverything will call iAct(of Param1) on each element of the list; the second will call iAct(of Param2). Additional methods may be added by simply creating new classes and adding interface iAct(of eachNewClass), without any need to change anything in DoItMagic.

My questions:

Are there any performance implementations with creating empty classes that are used as method selectors rather than as distinct ways of holding data (e.g. there might be a number of different classes that hold a single integer, but select different methods).
Does invoking methods via generics pose any performance problems in cases where everything can be type-checked at compile time?
What would be the performance implications in cases where things couldn't be checked until run-time (e.g. if a list holds a number of elements, not all of which will support any particular iAct(of type).
Is this overall approach a brilliant idea, crazy idea, or somewhere in between?

I like the way this approach seems to work, but I would be very sad if I developed a lot of code with it and discovered that while it performed well in initial testing it sometimes dogged in real applications. Any thoughts?

Re: Does the use of many trivial classes with generics pose a performance penalty?

Member 362614020-Jan-09 11:06

Member 3626140

20-Jan-09 11:06

Here is my experience.

You will have overall performance boost by using OOPS and Generics.

I have a project where I have used many classes and many generics almost in the same way as you are doing it. We did a performance test by bombarding with several request to the project and it performed better as against using OOPS without generics (many many classes and hence objects).

Generics gives the ability to precast and late binding, and also once loaded in memory it stays there to be consumed upon request.

Re: Does the use of many trivial classes with generics pose a performance penalty?

Mark Churchill20-Jan-09 14:36

Mark Churchill

20-Jan-09 14:36

Why not just use the build in List< U>.ForEach(instance.Act)?

If you need to use IEnumerable, then a trivial extension method would work:

static void ActOnABunchOfStuff< U>(IEnumerable< U> bunch, Action< U> action)<br />
{ foreach(var stuff in bunch) action(stuff); }

Use with:

int[] foo = {1,2,3,4,5};<br />
ActOnABunchOfStuff(foo, doItTarget.Act);

VB-i-cise it at your leisure Wink | ;)

Mark Churchill
Director, Dunn & Churchill Pty Ltd
Free Download: Diamond Binding: The simple, powerful, reliable, and effective data layer toolkit for Visual Studio.

Entanglar: .Net game engine featuring automatic networking and powerful HLSL gfx binding.

Re: Does the use of many trivial classes with generics pose a performance penalty?

supercat920-Jan-09 16:07

supercat9

20-Jan-09 16:07

Why not just use the build in List< U>.ForEach(instance.Act)?

Are you assuming Action< U> is a delegate for a void function that takes a single parameter of type U? I'm not terribly familiar with C# syntax, and I don't see any declaration for Action.

Also, I would guess that the last statement was supposed to be ActOnABunchOfStuff< integer>(foo, doItTarget.Act); but the board gobbled up what it thought was a tag?

If all the items in the list are of the same concrete type, I suppose that approach would work, at the expense of generating lots of silly little wrapper functions. Maybe that's no worse than generating silly little classes, but the generics approach I describe could offer another benefit that might be harder to achieve without generics: one could have a list of objects and do an enumerated invoke with something like if typeof(it) is iAct(of T) Then CType(it, iAct(of T)).Act(whatever). Not sure what the performance of that would be, but it would allow one to achieve a form of event handling without requiring every item to create a delegate for every different event that it supports. One could do such 'typeof/is' testing in a wrapper function, but that would seem a bit inelegant.

Re: Does the use of many trivial classes with generics pose a performance penalty?

Mark Churchill20-Jan-09 16:31

Mark Churchill

20-Jan-09 16:31

With that last statement, the type parameter U is inferred (at least in C#) from the type of foo (which is as you say an int).

System.Action(Of T) is in mscorlib, and has the signature you guessed. Theres also a couple of others with extra parameters.

I may have got a little confused with what you are trying to achieve. Invoking a method on each instance in a list, passing the same parameters?

I would use the equivalent of listOfThings.ForEach(x => x.SomeMethod(p1,p2,p3,etc));. This might be a little messy in VB though.

Re: Does the use of many trivial classes with generics pose a performance penalty?

supercat920-Jan-09 18:45

supercat9

20-Jan-09 18:45

The basic concept is that I have an class for objects that contain a number of objects that the class doesn't really understand in detail (an iEnumerable is a common example of such a thing, though hardly the most sophisticated) and I would like for code outside the class to be able to invoke methods on some or all of the objects within, generally passing the same parameters to all. In some regards similar to delegates, except (1) delegates are hard-wired for particular method-object pairs, and (2) there is no need to hold the method info for a delegate without holding a hard reference to the object.

One class I created using this approach (which seems to work nicely, though I haven't benchmarked its behavior in a program with hundreds of classes) manages something like event subscription, but using weak references. Any number of objects may subscribe to a 'publisher' object; performing .Exec(of T) on the publisher object will cause it to call function iAct(of T).Act on any subscribed object supporting interface iAct(of T). Subscription and unsubscription are O(1), non-locking, and thread-safe; an object will be unsubscribed if it (1) gets garbage-collected, (2) uses the Unsubscribe method of the Subscription object returned when the object originally subscribed, or (3) one of its iAct(of T) functions returns True when invoked.

My original intended application for this class would be in an application where a number of forms have controls that affect the same properties and should thus all affect each other. While events provide a nice way to achieve much of that functionality, all the forms need a reference to an object that will support all of the events they need. If new events are added, the linking object will have to be extended to support them. Worse, using events creates the possibility of memory or resource leaks if any objects don't get properly disposed. Finalizers won't do any good if delegates keep objects alive forever.

Using my actionLink class avoids these difficulties; if I create a class called e.g. volumeChangedParam, I can call Exec(of volumeChangedParam) on my event publisher object and any subscribed object that supports an iAct(of volumeChangedParam) will have its iAct(of volumeChangedParam).Act function called. The actionLink class doesn't have to know anything about volumeChangedParam or any of the other classes it works with; additional classes could be added to support other operations.

All this stuff seems to work fine, but I wouldn't want to engineer too much of a system around it if it turned out that, e.g. the .net framework performs wonderfully when an application uses less than a certain number of classes, and starts dogging badly if the application uses more.

Dynamic Blob field

dwolver19-Jan-09 9:21

dwolver

19-Jan-09 9:21

Trying to build a dynamic datatable and not sure how to define a blob column.
eg
DataTable dt = new DataTable();
dt.Columns.Add("uid");
dt.Columns.Add("test", Type.GetType("System.String"));

dt.Columns.Add("MyBlob",???

Re: Dynamic Blob field

Eddy Vluggen19-Jan-09 9:37

Eddy Vluggen

19-Jan-09 9:37

DataTable dt = new DataTable();
dt.Columns.Add("uid");
dt.Columns.Add("test", Type.GetType("System.String")); 

dt.Columns.Add("MyBlob",Type.GetType("System.Object"));

Just a guess, haven't run it through the compiler Frown | :(

I are troll Smile | :)

Re: Dynamic Blob field

Wendelius20-Jan-09 9:22