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Lars Fosdal

Pitfalls of Anonymous methods and capture

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5 hours ago, Lars Fosdal said:

Close, its a Self-Contained Compilable Example, sometimes also called a SSCCE, i.e. a Short SCCE. 


I'll rewrite the article for better readability. 


Hmmm... I knew I had read something like it before, but couldn't find it anywhere (in a meaning that made sense). The missing S did it.

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On 2/8/2019 at 2:19 PM, Lars Fosdal said:

Code that looks correct, and appear to compile alright, but which doesn't execute well.
Can you spot the error? See my blog post for a link to a SCCE.

  Handler: THandlerClass;
  hType: THandlers;
  for hType in [foo, bar]
  do begin
    case hType of
      foo: Handler := TFoo.Create;
      bar: Handler := TBar.Create;


FWIW, this is similar to the call-by-name problem (Jensen's device) in Algol 60.


And similar problems can happen if people do:

for I := 1 to 10 do
  MyRecord.Int := I;

The entire plain TList is now filled with pointers to the same record, and that contains the value 10. <g>

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