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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for December 23rd, 2020

PlasticSCM memories

Posted by jpluimers on 2020/12/23

Spending most of your career as an independent contractor, you bump into a lot of toolchains.

Part of those toolchains usually involved (and by now surely should involve) version control for both development and infrastructure configuration management.

I remember PlasticSCM quite well.

The really good part is the branch overview (called Branch Explorer) in the PlasticSCM UI, as it is:

They also have frequent updates, which however are hard to discover because there is no built-in update mechanism that notifies you of them.

Those updates are badly needed, because I kept bumping into bugs. Which is odd, because I bumped into far less issues when using UI layers for SVN, TFS, Mercurial and git (SourceTree being a major exception, but they seem to have recovered from a long period of bad versions a few years back).

So here are some of my gripes, that might have been fixed by now.

Read the rest of this entry »

Posted in Delphi, Development, PlasticSCM, Software Development, Source Code Management, Versioning | Leave a Comment »

Some links on MS UIA: UI Automation

Posted by jpluimers on 2020/12/23

For my link archive:

A Delphi implementation:

–jeroen

Posted in accessibility (a11y), Development, Software Development | Leave a Comment »

How to debug Delphi JSON export stack-overflows: watch the fields and their circular references

Posted by jpluimers on 2020/12/23

Unlike Delphi RTL XML support which is property based, the JSON support is field based.

By default, JSON uses all fields (no matter their protection level, so anything from strict private to published  is taken into account).

When there are cycles, they are not detected: it will just stack-overflow with a high set of entries like this:

REST.JsonReflect.{REST.JsonReflect}TTypeMarshaller.MarshalSimpleField($788BFB40,$78AB0150)
REST.JsonReflect.{REST.JsonReflect}TTypeMarshaller.MarshalData($78AB0150)
REST.JsonReflect.{REST.JsonReflect}TTypeMarshaller.MarshalValue((($A9B7E8, Pointer($AFE168) as IValueData, 80, 336, 2024472912, $78AB0150, TClass($78AB0150), 80, 336, 2024472912, 2,77471682335019e+34, 1,00022251675539e-314, 0,00000000737961e-4933, 2024472912, 202447,2912, 2024472912, 2024472912, ($78AB0150, nil), $78AB0150)),???)
REST.JsonReflect.{REST.JsonReflect}TTypeMarshaller.MarshalSimpleField($78A921D0,$78AA69C0)
REST.JsonReflect.{REST.JsonReflect}TTypeMarshaller.MarshalData($78AA69C0)
REST.JsonReflect.{REST.JsonReflect}TTypeMarshaller.Marshal(???)

The easiest way to debug this is to:

  1. Set breakpoints in procedure TTypeMarshaller<TSerial>.MarshalData(Data: TObject);
    1. First breakpoint on the for rttiField loop
      • Watch or log these values (the first two usually are the same, the last two too):
        1. ComposeTypeName(Data) which gives you the fully qualified name (including unit and class) of the type exposing the fields
        2. Data.ClassName as a sanity check
        3. rttiType.Name which should be the same as Data.ClassName
    2. Second breakpoint inside the for rttiField loop on the if not ShouldMarshalstatement
      • Watch or log these values:
        1. rttiType.Name inside the loop, it changes value to match rttiField.Name, because of a debugger bug not showing it as E2171 Variable 'rttiType' inaccessible here due to optimization.
        2. rttiField.Name the actual field name

Tricks to circumvent circular references:

  • remember that fields with a reference to function value are not marshaled, so they are an excellent way of shoehorning in a dependency in (the reference value will be a capture which includes the instance data of the function to be called)
  • applying a [JsonMarshalled(False)] attribute (be sure to use unit REST.Json.Types!) only works when used inside non-generic types:
    • a class like TMySoapHeaderValue<T: IInterface> = class will not expose these attributes
    • a class like TMySoapHeaderValue = class will expose these attributes

You can check the JsonMarshalled problem by setting a breakpoint inside function LazyLoadAttributes(var P: PByte): TFunc<TArray<TCustomAttribute>>; on the line Exit(nil); and watch the value for Handle^.

Posted in Conference Topics, Conferences, Delphi, Development, Event, Software Development | Leave a Comment »