'Check' function is executing multiple times in Inno Setup

Question

I am new to Inno Setup scripting and I am trying to install .NET framework 3.5 using below code as a prerequisite. The Check function is executing multiple times. C

Answer 1

Quoting Check parameter documentation:

Setup might call each check function several times, even if there's only one entry that uses the check function. If your function performs a lengthy piece of code, you can optimize it by performing the code only once and 'caching' the result in a global variable.

So the behavior is as designed.

And as your code is quite simple, I do not even think it needs any optimization. It's perfectly ok, if it runs few times.

---

Were it not, you can optimize it like this:

var
  Framework35IsNotInstalledCalled: Boolean; 
  Framework35IsNotInstalledResult: Boolean;

function Framework35IsNotInstalled: Boolean;
begin
  if not Framework35IsNotInstalledCalled then
  begin
    Framework35IsNotInstalledResult := IsDotNetDetected('v3.5', 1);
    Framework35IsNotInstalledCalled := True;
  end;

  Result := Framework35IsNotInstalledResult;
end;