Refresh shell associations in Inno Setup conditionally (only if a function is checked)

Question

As the title says how can I make that Inno Setup use the:

[Setup]
ChangesAssociations=yes 

Only when a certain function is checked:

function installation: Boolean;
begin
  Result := install.Checked; { only if this is checked }
end;

function portable: Boolean;
begin
  Result := porta.Checked;
end;

I need that association doesnt get called when I simply extract the portable version of my software.

Answer 1

Instead of using ChangesAssociations directive, call SHChangeNotify WinAPI function conditionally from CurStepChanged(ssPostInstall):

[Code]

const
  SHCNE_ASSOCCHANGED = $08000000;
  SHCNF_IDLIST = $00000000;

procedure SHChangeNotify(wEventID: Integer; uFlags: Cardinal; dwItem1, dwItem2: Cardinal);
  external 'SHChangeNotify@shell32.dll stdcall';

procedure CurStepChanged(CurStep: TSetupStep);
begin
  if CurStep = ssPostInstall then
  begin
    if installation then
    begin
      SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_IDLIST, 0, 0);
    end;
  end;
end;

This is what ChangesAssociations=yes internally does.

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Partially based on: Inno Setup refresh desktop.