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GeneralRe: What kind of dll use ftp/sftp mapping drive? Pin
Randor 13-Oct-20 20:39
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Dave Kreskowiak14-Oct-20 6:01
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Randor 14-Oct-20 10:22
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Questionhow to insert unknown amount of data into a database Pin
steven_noppe11-Oct-20 8:41
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AnswerRe: how to insert unknown amount of data into a database Pin
Luc Pattyn11-Oct-20 9:32
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AnswerRe: how to insert unknown amount of data into a database Pin
OriginalGriff11-Oct-20 9:33
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AnswerRe: how to insert unknown amount of data into a database Pin
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QuestionWhy am I not allowed to do this with events Pin
Keith Barrow9-Oct-20 2:20
professionalKeith Barrow9-Oct-20 2:20 
This is a genuine "why" question (as in the technical reason why the language prohibits what I want to do) rather than a "how do I get round the limitation?"*

I'm writing a WPF app and implementing a base class for a Command. The base implementation contains common logic to a set of subclasses which must have the Database connection in a non-busy state before they can execute. If the busy state changes, calling CanExecuteChanged?.Invoke(this, e); is naturally fine in this base. The problem is I have secondary conditions in the subclasses which also prevent execution - on those conditiond changing I'd want to call CanExecuteChanged?.Invoke(this, e); from the subclass - this isn't allowed and I can't work out the reasoning.

My current working theory is the even is like syntactic sugar over a delegates (or something) and the part to raise the event is private (which would prevent raising outside the base class) the whereas the subscription side is public (so you can subscribe from an unrelated type).That doesn't explain why the "raise" part isn't protected, or somehow optionally private/protected. There is a gap in my knowledge somewhere.
  • I have a couple of solutions for this: like exposing the delegate with a backing field and calling that, or the one I'll probably adopt which is to expose a protected event to raise the event seems more explicit.
KeithBarrow.net[^] - It might not be very good, but at least it is free!

AnswerRe: Why am I not allowed to do this with events Pin
Richard Deeming9-Oct-20 3:12
mveRichard Deeming9-Oct-20 3:12 
GeneralRe: Why am I not allowed to do this with events Pin
Keith Barrow9-Oct-20 4:19
professionalKeith Barrow9-Oct-20 4:19 
QuestionHow to read from serial port until timeout of no more data received? Pin
td17768-Oct-20 14:27
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AnswerRe: How to read from serial port until timeout of no more data received? Pin
Luc Pattyn8-Oct-20 15:27
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GeneralRe: How to read from serial port until timeout of no more data received? Pin
td17768-Oct-20 16:36
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GeneralRe: How to read from serial port until timeout of no more data received? Pin
Luc Pattyn9-Oct-20 2:25
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AnswerRe: How to read from serial port until timeout of no more data received? Pin
Gerry Schmitz8-Oct-20 19:27
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GeneralRe: How to read from serial port until timeout of no more data received? Pin
td17769-Oct-20 12:16
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GeneralRe: How to read from serial port until timeout of no more data received? Pin
Gerry Schmitz9-Oct-20 15:10
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AnswerRe: How to read from serial port until timeout of no more data received? Pin
Richard MacCutchan8-Oct-20 23:55
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AnswerMy (temporary?) solution Pin
td17769-Oct-20 12:25
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QuestionCOM exception loss Pin
Member 126326017-Oct-20 21:57
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AnswerRe: COM exception loss Pin
Richard MacCutchan7-Oct-20 22:35
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GeneralRe: COM exception loss Pin
Member 126326017-Oct-20 23:03
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GeneralRe: COM exception loss Pin
Richard MacCutchan7-Oct-20 23:25
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GeneralRe: COM exception loss Pin
Member 126326017-Oct-20 23:58
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GeneralRe: COM exception loss Pin
Richard MacCutchan8-Oct-20 0:24
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