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Search found 3 results on 1 pages for 'mghie'.

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• Can Delphi dragging be "promoted" to docking?

  - by mghie

  I have a TPageControl whose pages are all various forms that are attached using ManualDock(). The user should be able to rearrange the tabs by dragging them, which works already. It should however also be possible to undock the docked forms. For now I have the following code: procedure TMainForm.PageControlMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); begin if (Button = mbLeft) and (Shift * [ssShift, ssCtrl] = []) and PageControl.DockSite then begin PageControl.BeginDrag(False, 32); end; end; If either the Shift or the Ctrl key are held down, then a docking operation will be started, otherwise the tabs can be rearranged by dragging them. Using the keys as modifiers is awkward though. Is there any way to cancel the active drag operation when the mouse cursor is outside of the tab area of the page control, and start docking the child form? This is with Delphi 2009.

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• How can I have a Foo* iterator to a vector of Foo?

  - by mghie

  If I have a class that contains a std::list<Foo>, how can I implement iterators to a Foo* collection, preferably without using boost? I'd rather not maintain a parallel collection of pointers. For now I have std::list<Foo>, mostly so that removing or inserting an element does not invalidate all other iterators, but would it be possible to implement other iterators too, so that the collection type used in the implementation is opaque to the user of the class?

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• Achieving Thread-Safety

  - by Smasher

  Question How can I make sure my application is thread-safe? Are their any common practices, testing methods, things to avoid, things to look for? Background I'm currently developing a server application that performs a number of background tasks in different threads and communicates with clients using Indy (using another bunch of automatically generated threads for the communication). Since the application should be highly availabe, a program crash is a very bad thing and I want to make sure that the application is thread-safe. No matter what, from time to time I discover a piece of code that throws an exception that never occured before and in most cases I realize that it is some kind of synchronization bug, where I forgot to synchronize my objects properly. Hence my question concerning best practices, testing of thread-safety and things like that. mghie: Thanks for the answer! I should perhaps be a little bit more precise. Just to be clear, I know about the principles of multithreading, I use synchronization (monitors) throughout my program and I know how to differentiate threading problems from other implementation problems. But nevertheless, I keep forgetting to add proper synchronization from time to time. Just to give an example, I used the RTL sort function in my code. Looked something like FKeyList.Sort (CompareKeysFunc); Turns out, that I had to synchronize FKeyList while sorting. It just don't came to my mind when initially writing that simple line of code. It's these thins I wanna talk about. What are the places where one easily forgets to add synchronization code? How do YOU make sure that you added sync code in all important places?

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