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in Technique[技术] by (71.8m points)

delphi - Loosen "Local procedure/function assigned to procedure variable" restriction gracefully

Consider the following test-case:

{ CompilerVersion = 21 }
procedure Global();

  procedure Local();
  begin
  end;

type
  TProcedure = procedure ();
var
  Proc: TProcedure;
begin
  Proc := Local;  { E2094 Local procedure/function 'Local' assigned to procedure variable }
end;

At line 13 compiler emits message with ERROR level, prohibiting all of the cases of such local procedures usage. "Official" resolution is to promote Local symbol to the outer scope (ie: make it a sibling of Global) which would have negative impact on code "structuredness".


I'm seeking the way to circumvent it in most graceful manner, preferably causing compiler to emit WARNING level message.

See Question&Answers more detail:os

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by (71.8m points)

Your best bet is to declare it as reference to procedure using the new anonymous methods feature and then you can keep everything nicely encapsulated.

type
  TProc = reference to procedure;

procedure Outer;
var
  Local: TProc;
begin
  Local := procedure
    begin
      DoStuff;
    end;
  Local;
end;

This gets around the issues that Mason describes by capturing any variables local to the anonymous function.


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