Visual Basic

28-Apr-08 19:06

Hello,

Is it possible to get as parameter a string and accordingly to call to the function that have the same name, without using cases but with some casting or something similar?
For example

'fName value passed to the function is for example "MyFunctionToBeCalled"
private sub LoadData(fName as string)
call "casting"(fName)
end sub

private function MyFunctionToBeCalled()
'DoSomething
end function

Thank you

Shay Noy

Christian Graus28-Apr-08 19:36

28-Apr-08 19:36

You can do this with reflection, but is seems nasty to me.

Christian Graus

Please read this if you don't understand the answer I've given you

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

helelark12328-Apr-08 19:57

28-Apr-08 19:57

Thank you, I will check this.
Actually, I have in database a list of users that I am sending to them an email (everyone get a different email) according to multiple criterias. Each criterias return information and this information is returned by different functions that are in my code.
So, I have a table in my database that define for each user which functions to pull out information and then this is the reason that I need to call a function according to the string I get from the database.
This is the best way I found to accomplish this task.
Any supposition?

Thank you

Shay Noy

Christian Graus28-Apr-08 20:27

28-Apr-08 20:27

I think you need an enum that defines the different possible criteria, and one method that takes this enum and returns the data asked for

helelark12328-Apr-08 20:36

28-Apr-08 20:36

The problem is that the criteria are created dynamically. I have an interface that build criterias and for each criteria link to all the users that will get an email according to it. This interface is the trigger to fill my database.
If i will use enum, I will have to update my code every new criteria instead of adding new record(s) to my database.

The method you are suggesting to write, if I understood right, will include a select case of the enum items and each case will call to the according function.Why do not do this directly from the database, getting the method name (as string), use reflection (as you said) and then call to the function?

Thank you for your replies.

Shay Noy

Christian Graus28-Apr-08 20:39

28-Apr-08 20:39

But, if you add criteria, you need to write new methods to call in order to get the data you want anyhow, right ? If the data comes from a method that already exists, then you can use an enum value that already exists.

helelark12328-Apr-08 21:17

28-Apr-08 21:17

You are right.
I trying to reproduce all the scenario how it will work but I still have a problem in this way because also in your way I will need to use reflection.
This is the scenario:
I have an enum:
public enum criterias
criteria1
criteria2
criteria3 ...
end enum

From my database I need to know for each user which criteria is linked to.
My database example:
Col1: UserID {1,2,3,4}
Col2: Criteria (Criteria1,Criteria2,Criteria1,Criteria3}

Public function f()
'returns for each user wich criteria
criteriaFromDb=LoadCriteriaFromDb

select case criteriaFromDb
case criterias.criteria1
call f1
case criterias.criteria2
call f2
case criterias.criteria3
call f3
end case
end function

If I am right until this line, so criteriaFromDb is a string that I pull out from Mydatabase and now I still need to "convert" it to enum (I know how to do this) and it is actually same as "converting" string to function.

Thanks

Shay Noy

Christian Graus28-Apr-08 21:35

28-Apr-08 21:35

shaynoy wrote:
I still need to "convert" it to enum (I know how to do this) and it is actually same as "converting" string to function.

Not at all. You make sure your enum has int values that correspond to the int values stored in your DB, and you just cast it. No reflection needed.

helelark12328-Apr-08 22:54

28-Apr-08 22:54

Now it is clear, thank you very much

Shay Noy

Sourcecontrol and contextmenustrip

Mycroft Holmes29-Apr-08 1:53

Mycroft Holmes

29-Apr-08 1:53

I have used delegate functions for something like this, the database actually holds the method name but the methos must have the same footprint. I'll see if I can find the code tomorrow.

Never underestimate the power of human stupidity
RAH

Gab2328-Apr-08 12:57

Gab23

28-Apr-08 12:57

Hi,

I'm having a problem with a contextmenustrip control. This menu appears when the user is right clicking on a control. When the click event of a first-level contextmenu item is called, I can use the sourcecontrol property in order to retrieve the control that has been clicked. However, when I the click event of a second-level contextmenu item is called, the program is not able to retrieve the right control. The program crashes and give me the following error: System.NullReferenceException.

Any help is welcome.

Gabriel

String evaluation

Phusys28-Apr-08 8:42

Phusys

28-Apr-08 8:42

Hi,
i've a problem with string evaluation.
I need a function that return me the value of a variable passed throught his name...something like this:

<br />
Public Variable As Integer = 2<br />
<br />

<br />
Function Evaluate(ByVal name as String)<br />
//some vb.net code<br />
//return VariableValue<br />
End Function<br />

<br />
Evaluate("Variable") -> this have to return me the value 2<br />

Thanks

Ashish Sehajpal28-Apr-08 9:32

Ashish Sehajpal

28-Apr-08 9:32

Function Evaluate(ByVal name as String) as Int32<br />
try<br />
return convert.toInt32(name)<br />
ctach ex as exception<br />
return 0<br />
end try<br />
End Function

Ashish Sehajpal

Phusys28-Apr-08 10:15

Phusys

28-Apr-08 10:15

thanks!

Another question, if i want to process also String variable like this:

Public Variable as String = "abcd"

Evaluate("Variable") -> this must return abcd

Thanks

helelark12328-Apr-08 18:58

28-Apr-08 18:58

If I understood right, you say that passing as parameter the name of the variable to the function and converting it to int32 will return its value?
It is wrong or I perhaps miss something. Do you mean that this following code is running? Otherwise, please show your code.

Public Variable As Integer = 2

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
MsgBox(Evaluate("Variable"))
End Sub

Function Evaluate(ByVal name As String) As Int32
Try
Return convert.toInt32(name)
Catch ex As Exception
Return 0
End Try
End Function

Shay Noy