Incorrect installation when R installation is cancelled

[trybik]

Hi again,

if you cancel R installation then installer by default proceeds further and fails to launch the app, even if you do have R already installed (in a different, compatible version). In the latter case the paths are not set correctly. There is no "cancel" nor "back" button in the step following the R installer, nor an automatic rollback/cancellation.

Best possibly would be to attempt to detect another, newer version of R (as a step torwards #24 ), and only if not found auto-rollback/cancel the installer. Independently, a "cancel" button in each step would make sense.

Best, Mik

[Dripdrop12]

I completely agree. We can probably tackle this and #24 in the same hotfix.

[Dripdrop12]

Did we address this in your most recent pull request?

[trybik]

No, the late "Cancel" plus rollback part is not there AFAIK. When working on #73, before I've discovered the Abort function, I actually had some hacks implemented that could be useful here (from the ".iss" file):

// Exit current process
procedure ExitProcess(exitCode:integer);
  external '[email protected] stdcall';

// Get uninstallation command string
function GetUninstallString(): String;
var
  sUnInstPath: String;
  sUnInstallString: String;
begin
  sUnInstPath := ExpandConstant('Software\Microsoft\Windows\CurrentVersion\Uninstall\{#emit SetupSetting("AppId")}_is1');
  sUnInstallString := '';
  if not RegQueryStringValue(HKLM, sUnInstPath, 'UninstallString', sUnInstallString) then
    RegQueryStringValue(HKCU, sUnInstPath, 'UninstallString', sUnInstallString);
  Result := sUnInstallString;
end;

// Trigger explicit uninstallation
procedure Uninstall();
var
  sUnInstallString: String;
  iResultCode: Integer;
begin
  sUnInstallString := GetUninstallString();
  if sUnInstallString <> '' then
  begin
    sUnInstallString := RemoveQuotes(sUnInstallString);
    Exec(sUnInstallString, '/SILENT /NORESTART /SUPPRESSMSGBOXES','', SW_HIDE, ewWaitUntilTerminated, iResultCode)
  end;
end;

// Is R installed?
function RDetected(break: boolean): boolean;
var
    v: Integer;
    success: boolean;
begin
  ...
  if (not success and break) then
  begin
    SuppressibleMsgBox(Format('Error: R >= %s not found',[RVersions[RVersions.Count - 1]]), mbError, MB_OK, MB_OK);
    Uninstall();
    ExitProcess(1);
  end;
  Result := success;
end;

// If R is not detected, it is needed
function RNeeded(): boolean;
begin
  Result := not RDetected(false);
end;

// Save installation paths
procedure SaveInstallationPaths();
var
  RPath, ChromePath, IEPath, FFPath, PandocPath: string;
begin
    ...
    if Length(RRegKey) = 0 then
      RDetected(true);
    ...
end

Feel free to use that if it helps. An explicit "Cancel" button could also use the "Uninstall(); ExitProcess(1)" sequence, +/- uninstalling R, Pandoc or Chrome if they were also installed.