Python detection code for InnoSetup

[Robert Olson]

Sending this off for future reference since it doesn't belong in the .iss 
I'm working on at the moment.

--bob
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[Code]
var
  PythonPaths, PythonNames : TArrayOfString;
  PythonPathVals: TArrayOfString;
  HavePy22, HavePy23, MultiplePythonInstalls: Boolean;

function InitializeSetup(): Boolean;
var
	py22path, py22name, py23path, py23name: String;

begin
  if RegQueryStringValue(HKLM, 'Software\Python\PythonCore\2.2\InstallPath', '', py22path) then begin
	HavePy22 := true;
    RegQueryStringValue(HKLM, 'Software\Python\PythonCore\2.2\InstallPath\InstallGroup', '', py22name)
  end else begin
    HavePy22 := false
  end;

  if RegQueryStringValue(HKLM, 'Software\Python\PythonCore\2.3\InstallPath', '', py23path) then begin
	HavePy23 := true;
    RegQueryStringValue(HKLM, 'Software\Python\PythonCore\2.3\InstallPath\InstallGroup', '', py23name)
  end else begin
    HavePy23 := false
  end;

  if HavePy22 and HavePy23 then begin
	SetArrayLength(PythonPaths, 2);
	SetArrayLength(PythonNames, 2);
	SetArrayLength(PythonPathVals, 2);

    PythonPaths[0] := py22path
	PythonPaths[1] := py23path
	PythonNames[0] := py22name
	PythonNames[1] := py23name

	{ Default to the latest one. }
	PythonPathVals[1] := '1';

	MultiplePythonInstalls := true;
   end else begin
	   MultiplePythonInstalls := false;
	end;

  Result := true;

end;


function ScriptDlgPages(CurPage: Integer; BackClicked: Boolean): Boolean;
var
  I, CurSubPage: Integer;
  Nextt, NextOk: Boolean;
  pythonPath: String;
begin
    if (not BackClicked and (CurPage = wpSelectDir)) or (BackClicked and (CurPage = wpSelectProgramGroup)) then begin
		{ Insert a custom wizard page between two non custom pages }
		{ First open the custom wizard page }
		ScriptDlgPageOpen();
		{ Set some captions }
		ScriptDlgPageSetCaption('Choose python version.');
		ScriptDlgPageSetSubCaption1('Multiple versions of Python are installed on this system.');
		ScriptDlgPageSetSubCaption2('Select the version you wish to use for the Access Grid Toolkit, and click Next.');


		Nextt := InputOptionArray(PythonNames, PythonPathVals, True, False);

		for i := 0 to GetArrayLength(PythonPathVals) - 1 do begin
			if (PythonPathVals[i] = '1') then begin
				pythonPath := PythonPaths[i];
				break
			end;
		end;

		MsgBox(pythonPath, mbInformation, MB_OK);

		if not BackClicked then
			Result := Nextt
		else
			Result := not Nextt;
		ScriptDlgPageClose(not Result);
    end	else begin
		Result := true
	end;
end;

function NextButtonClick(CurPage: Integer): Boolean;
begin
  if MultiplePythonInstalls then
	  Result := ScriptDlgPages(CurPage, False)
  else
	Result := True
end;

function BackButtonClick(CurPage: Integer): Boolean;
begin
  if MultiplePythonInstalls then
	  Result := ScriptDlgPages(CurPage, True)
  else
	Result := True
end;