How do you determine if an object has be constructed in Inno Setup Pascal Script?

问题

How do I check that my checkbox has been created / constructed and can be used to check if checked?

[Code]

var
  MyCheckBoxThatMayExistOrNot: TNewCheckBox;

procedure Whatever();
begin
  { Check if MyCheckBoxThatMayExistOrNot exists and checked }
  if ????? and MyCheckBoxThatMayExistOrNot.Checked then
  begin
    ...
  end;
end;

TIA!!

回答1:

Compare the variable value against nil:

if (MyCheckBoxThatMayExistOrNot <> nil) and MyCheckBoxThatMayExistOrNot.Checked then

An equivalent is use of Assigned function:

if Assigned(MyCheckBoxThatMayExistOrNot) and MyCheckBoxThatMayExistOrNot.Checked then

---

You might want to explicitly initialize the variable to nil in InitializeSetup or InitializeWizard, but it should not be necessary: Are global variables in Pascal Script zero-initialized?

来源：https://stackoverflow.com/questions/62708973/how-do-you-determine-if-an-object-has-be-constructed-in-inno-setup-pascal-script