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PeterBelow

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PeterBelow last won the day on July 7

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  1. PeterBelow

    Delphi not responding to errors..

    You can tell the debugger to ignore certain types of exceptions, this is offered as a button on the exception dialog you get when the IDE debugger catches an exception. Perhaps you did this by accident. Call up the Tools --> Options dialog,on the left scroll down to the end of the list. There you find a "debugger options" node with two subnodes for language and OS exceptions. The associated pages list the exception types to ignore; you can reactivate them there as well. see the attached dcreenshot, unfortunately from a german IDE.
  2. PeterBelow

    Cannot login to Quality Central - who to contact?

    Can you get to members.embarcadero.com and log in there with your EDN account?
  3. PeterBelow

    Best practices for system migration?

    You only need the licence key, which you can copy from the Licence manager via clipboard.
  4. PeterBelow

    Bad build a mystery

    Did you check the dpr file for bad line ends (only cr or only lf)? What happend to me some time ago was that the IDE inserted a new form unit name in the DPR file smack in the middle of an existing one, which of course did not build anymore and resulted in some weird error messages (no IDE crash, though). I found out that the file had become corrupted, with mix of linebreak styles. I never found out how that happended...
  5. PeterBelow

    Database connection as parameter in class creation

    For 1: If you like to set up the connection at design-time in a datamodule the approach is OK, and you do not need to pass the connection object as a Var parameter. Objects are reference types, so you pass a reference to the connection object, and that can even be done as const, since you can work with the object's properties or pass the reference on this way as well. Just do not free the connection object in the "record class", it belongs to the datamodule and will be freed by it when the datamodule is destroyed. For 2: "Best" is hard to define in this context. For a complete separation of the UI from the data it works with you need a bit more than just keeping connection and query/table objects out of the forms/frames and business logic code out of event handlers there. But writing a model-view-presenter framework or a full-blown object-relational mapper (ORM) framework from scratch is a lot of work. For smaller projects it may not pay to go to these length, especially if you only aim for one platform with a desktop client.
  6. Using threads to do thing in parallel obviously only works efficiently if the "things" do not depend on each other. As soon as a thread has to wait on the results of another the processing slows down and the chance of deadlocks goes up. Also, using more threads than the hardware has cores/cpus quickly gets you to a point of diminishing returns, since the OS has some administrative overhead to manage the threads. So, don't overdo it, especially in a scenario like a parallel for loop, where the code can only continue after the loop has finished completely it may be more efficient to split the loop into several and run each in its own thread. If the loop does not have that many iterations and executes each round fairly quickly setting up the individual tasks in a parallel for may consume more time than you gain by doing stuff in parallel. There is no substitute for thorough testing and timing in such a scenario.
  7. No, you can operate on several canvases (of offline bitmaps or metafiles) in parallel, its is just a little bit less efficient since each canvas has to create its own font, pen, brush instead of using an existing one from the VCL sharing pool.
  8. If you work with a TCanvas in background threads always wrap your code in canvas.lock; try ...operate on canvas here finally canvas.unlock; end; The VCL has a build-in mechanism to optimize use of GDI objects, which is shared between all TCanvases used, and his mechanism is not thread-safe. Locking the canvas makes sure it does not use this mechanism while it is locked.
  9. PeterBelow

    multi forms with thread in each

    If you want to use a database that requires COM (e.g. via dbGo) inside a thread you have to call CoInitialize at the start of the execute method and CoUninitialize at the end. You are not doing that, your InitializeDatabase method calls CoUnInitialize, so any subsequent use of the database connection may not work as intended. You thread Execute method does not contain a loop, after one pass through the code the thread will exit. Also keep in mind that database connections are usually bound to the thread that created them, so using a dataset bound to the connection created by the thread in another thread (e.g. in the main thread through a Synchronize call) may either not work or involve some internal thread synchronization done by the framework you are using (COM objects using appartment threading are such a case) that may block until the code returns to the message loop. Something else that may foul your design: Creating a datamodule inside a thread is not a problem per se, but if you have design-time links of components on forms, frames, other datamodules to stuff on this datamodule (or vice versa) the way the VCL streaming mechanism resolves them may torpedo your intent. This mechanism is not thread-safe, and it resolves the links using the Name of the component linked to, and it looks for the container (form etc.) in a global list, where it will only find the first created instance of the container, even if you have created several.
  10. PeterBelow

    RIO: Start Debug Session changes source

    Thanks for sharing the solution.
  11. PeterBelow

    RIO: Start Debug Session changes source

    This is not normal behaviour, i have never encountered that myself with Rio. Do you also get that if you do a build before starting the debug session?
  12. PeterBelow

    Why control methods (OnClick) can't be defined in Form Private section?

    The form streaming process relies on run-time type information (the old styele), and that is only generated for published members of a class.
  13. PeterBelow

    Importing Excel2016 Type library into Delphi

    If you execute the import component dialog and select "import type library" you should get a list of the installed type libraries on the next page of the wizard. Don't you see a "Microsoft Excel xx.x Object Library" in that list?
  14. PeterBelow

    Funny Code in System.Types

    The point is that the code is plain wrong, the last else in both if trees needs to cast value.x and value.y, respectively, not result.x/y, which has not been set at those points!
  15. PeterBelow

    redefined anonymous method - bug or my mistake?

    Well, TRunner.TCallback is closer in scope, so I would expect the compiler to use it instead of the global TCallback, so that does look like a bug. Should be easy enough to work around, though, just specify TRunner.TCallback as type for the property and its field. Of course it's a bit problematic to have this kind of nameing conflict in the first place, not (only) for the compiler but also for a programmer trying to make sense of the code 😉. Delphi 10.3 Version 26.0.33219.4899 still shows this behaviour, by the way.
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