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I'm using entity framework I'm trying to make a general function that works for an object for which the class is known only at runtime. I have an instruction that use an expression similar to this :
context.ChangeTracker.Entries(of Myobj1)
Of course that if I know the class name "MyObj1" the above expression is working correctly.
But at runtime , I only have an variable :
Dim tp as type which contain the class , and i need an expression like this :
context.ChangeTracker.Entries(of tp)
Thank you !
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My bad. I misunderstood what you were doing.
In order for a Generic to work, the types used must be known at compile-time, not run-time.
I've never done what you're trying to do, nor seen it done specifically with EF before, but you may want to look into these[^] possibilities. You'd have to create a method that generates the entire ChangeTracker.Entities() call at runtime.
modified 21-Apr-15 8:42am.
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I'm using vb.net , and I have this situation :
I have a button on the form( Mybutton1 ) .
I have also a sub that contains a for..next loop :
.....
for I=1 to nr1
{.... some instructions...}
if condition1 then Mybutton1.enable=true
Next
On every step of this For loop , the button became enabled when a condition is true .In this case I want that this loop to stop until the user press the Button. ( the button's click event , at the end has some instructions that makes the button disabled again )
Is there any way to do this behavior ?
Thank you !
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You probably don't want a for loop.
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I described my problem in my post.
So I need response for the case when I need a for loop.
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Contrarywise; you described a case where you don't want a for loop.
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I described a case when I already have a for loop.
And if in one step of this loop , the button became enabled , the loop should be stopped , and to go to to the next step the user should press the button.
If the condition is always false , the for loop should continue until the end without interruption.
This is my case.
Is there any solution for this case ?
Thank you !
( I'm not asking if there's another way to do , because you can't give an opinion since you don't know nothing about my program , except the little part that I have described here)
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You should add a test in your loop to see if the button is enabled, so you can exit the loop if it is. There are other ways to do this, which is why PIEBALDconsult[^] made the comments that he did.
dilkonika wrote: you can't give an opinion since you don't know nothing about my program
Comments like that do not endear you to people here. And given the number of questions you have posted recently, you really do not want to get a reputation as someone who does not accept well meaning advice.
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I think you misunderstand what I mean with my words.
I mean that someone can't give an opinion that should I use or not an For..Next loop because he don't know all the logic of my program.
So why you want to comment the question instead of try to give a response. The question is very clear.
If there's no answer , respond "it's not possible.".
And about the reputation , I'm not interested , because I'm more interested about the answers of my questions.
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dilkonika wrote: And about the reputation , I'm not interested , because I'm more interested about the answers of my questions.
If you won't listen the answers you're given, you gain a reputation where nobody will give them to you.
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sorry , but could you tell me what is the response that should I accept ? Until now in the answers I read only words. I think that if someone doesn't know an idea about the response is better not to respond ( as is happen for some of my other recent questions where nobody has given a single response. )
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dilkonika wrote: So why you want to comment the question instead of try to give a response.
I gave you a response.
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How about I restart PIEBALD's answer.
You CAN'T do this with a for loop.
A Windows Forms app is a state machine that reacts to inputs like mouse and keyboard events. You CAN'T stop a loop and wait for input as your UI code is busy in the middle of the loop and cannot process input events until the code goes back to an idle state, meaning it's not executing any of your code!
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Ok , I'm ready to accept any other solution , but first let explain something :
In the form I have this button.
This button do some actions. and may be enable on several situations . so this button does not depend on the for..Next loop. so even the For..next loop will be never executed , the code inside the button may be executed on several occasions when the user press the button.
The for ..next loop is on another sub , that when is executed , sometimes can make the button enabled. On this cases , the loop should wait until the user press that button and after continue to next step.
What are your new solutions to resolve this case ?
Thank you !
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I have no idea. Why? Because we don't know the business rules and logic of your application. Who's fault is that? Hint: Not ours.
Since we know nothing of what you're really trying to do with this, there's really nothing that we can tell you to make something like this work. The only answer we can give is why you're current design will NOT work.
Which we've done.
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Ok , I give you some additional details :
I'm using the form to edit , create and modify records form a database.
The button for which I'm talking has all the necessary code to test the new record created by user , and if the test is done without problems , the new record is saved. But this button can test and save records one by one ( so if a user create a new record , he should press the button before create another ).
Now , I have added a new function in my form : Copy paste records.
So the user can select one ( or several ) existing records , and press copy on the right click menu.
When a copy is made , a list is created that contains all the records that are copied and should be pasted.
for the Paste actions , I have this For..next loop.
But the records that are copied , should be pasted one by one.
So a new record is created that is a copy of the first element on the copy-list.
At this point , the loop should stop , and user can make the changes needed for this copy and after should press the button to do the actions needed and to save this record.
After the loop can continue with the same logic for the other records.
This is all.
Can you give me a new idea ?
Thank you !
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dilkonika wrote: for the Paste actions , I have this For..next loop.
But the records that are copied , should be pasted one by one.
So a new record is created that is a copy of the first element on the copy-list.
At this point , the loop should stop , and user can make the changes needed for this copy and after should press the button to do the actions needed and to save this record.
After the loop can continue with the same logic for the other records.
From this description you have given I would consider 2 approaches to your problem
- The user has to individually copy / edit a duplicated row and then click on save
- You allow the user to specify how many rows that they want to create, then allow them individually save each row.
personally I feel if you continued on the path that you want to take it, It would make your application very hard to maintain.
Every day, thousands of innocent plants are killed by vegetarians.
Help end the violence EAT BACON
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This isn't something you would normally do, and prior to .NET 4.5 would be virtually impossible. (You could re-write your code to use a state-machine, but it wouldn't resemble a For loop.)
However, if you're using .NET 4.5, you can create a hacky solution using Async / Await:
Private _buttonClickedSource As TaskCompletionSource(Of Boolean)
Protected Sub MyButton_Click(ByVal sender As Object, ByVal args As EventArgs) Handles MyButton.Click
Dim tcs As TaskCompletionSource(Of Boolean)
tcs = Interlocked.Exchange(_buttonClickedSource, Nothing)
If tcs IsNot Nothing Then
tcs.TrySetResult(True)
End If
End Sub
Private Async Function DoYourFunkyThing() As Task
...
For i = 1 To nr1
...
If condition1 Then
Dim tcs As New TaskCompletionSource(Of Boolean)()
Interlocked.Exchange(_buttonClickedSource, tcs)
MyButton.Enabled = True
Await tcs.Task
MyButton.Enabled = False
End If
Next
End Function
The compiler will re-write this method to use a state machine, but you can still write your code as if it was a For loop.
Async (Visual Basic)[^]
Asynchronous Programming with Async and Await (C# and Visual Basic)[^]
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Thanks to all for your down Votes.
It's seems that those who doesn't have the idea how to resolve the problem , attack the question. Sorry friend what do you want , to ask : " ... It's true that 1+1=2 ?"
It's sure that for this question exist a solution ( even prior to .NET 4.5 )
( for sure , it's not me that found the solution , because I don't pretend to be a high level professional ).
But I will not post here the solution.
Maybe some of those that have down voted , try to find the answer , because someone that pretend to have a professional level , should show this with an answer not with a down vote.
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Yeah, about the reputation...
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And why have you posted this abusive response to my message, when I've tried to help you? 
Your account is currently on 8 "abusive/troll" votes. Two more, and you'll be kicked off the site.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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and what is the abusive part of my post ?
If you are one of them that down voted , well , sometimes the truth is hard to accept.
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I posted a genuine answer to your question.
You replied with a message complaining about down-votes, and stating that you found an answer elsewhere, but you're not going to share it with us because none of us are "professional" enough.
And you can't see the abusive part of that? 
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Maybe was a mistake from me that I posted my replies to your message.
My replies was intend to be a general replies to all of those that have down voted. Because I think each down vote should have an argumentation.
And I found the answer elsewhere ( it is not my solution ) , but I don't post here only for those that have down voted. ( if you are one of them , this is for you too). The reason is that I think that when someone doesn't know the solution , attack the question. For these people I thing that they aren't professional.
Instead of simply down vote a question :
1) Find a solution
2) Ignore the question
3) Say " I'm sorry I don't know "
4) Down vote , but with arguments why this question has problems.
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dilkonika wrote: My replies was intend to be a general replies to all of those that have down
voted.
That'd be me.
dilkonika wrote: And I found the answer elsewhere ( it is not my solution ) , but I don't post
here only for those that have down voted.
Not a downvote, but an abuse-flagging. It is not something that is flagged on a question, but on an account. Read his post again.
dilkonika wrote: The reason is that I think that when someone doesn't know the solution , attack
the question.
More likely cause would be being rude against volunteers.
dilkonika wrote: For these people I thing that they aren't professional.
This is spare time, you should not be expecting a business-treatment.
dilkonika wrote: Instead of simply down vote a question :
Demands are hardly going to work. There's some basic rules for the forum as a sticky on top of each page. I think it is worded correctly.
Instead of making demands, try kindness.
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
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