Command Line Parms: Function Return Type As Array? - arrays

Question

Here's the current problem:
Executing an uninstall string with command line parameters following this solution:
Here's what we have in the form of non-functioning code:
const MAX_PATH = 260;
function GetUninstallString(): TArrayOfString;
var
sUnInstPath: String;
sUnInstallString: String;
sUnInstallStringPrm: String;
begin
sUnInstPath := ExpandConstant('Software\Microsoft\Windows\CurrentVersion\Uninstall\{#MyAppName}');
sUnInstallString := '';
if not RegQueryStringValue(HKLM, sUnInstPath, 'UninstallString', sUnInstallString) then
RegQueryStringValue(HKCU, sUnInstPath, 'UninstallString', sUnInstallString);
if sUnInstallString = '' Then
Begin
sUnInstPath := ExpandConstant('Software\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{#MyAppName}');
RegQueryStringValue(HKLM, sUnInstPath, 'UninstallString', sUnInstallString);
End;
if sUnInstallString <> '' Then
Begin
sUnInstallStringPrm:= copy(sUnInstallString, pos(' ', sUnInstallString) + 1, MAX_PATH);
MsgBox(sUnInstallStringPrm, mbInformation, MB_OK);
Delete(sUnInstallString, pos(' ', sUnInstallString), MAX_PATH);
End;
Result := [sUnInstallString, UnInstallStringPrm];
end;
/////////////////////////////////////////////////////////////////////
function IsUpgrade(): Boolean;
begin
Result := (GetUninstallString() <> '');
end;
/////////////////////////////////////////////////////////////////////
function UnInstallOldVersion(): Integer;
var
sUnInstallString: String;
iResultCode: Integer;
begin
// Return Values:
// 1 - uninstall string is empty
// 2 - error executing the UnInstallString
// 3 - successfully executed the UnInstallString
// default return value
Result := 0;
// get the uninstall string of the old app
sUnInstallString := GetUninstallString();
if sUnInstallString <> '' then begin
sUnInstallString := RemoveQuotes(sUnInstallString);
if ShellExec('open', sUnInstallString, '','', SW_SHOW, ewWaitUntilTerminated, iResultCode) then
Result := 3
else
Result := 2;
end else
Result := 1;
end;
/////////////////////////////////////////////////////////////////////
procedure CurStepChanged(CurStep: TSetupStep);
begin
if (CurStep=ssInstall) then
begin
if (IsUpgrade()) then
begin
UnInstallOldVersion();
end;
end;
end;
There is very little info on how to use GetUninstallString in this context. Possible at all?
Not sure if, as an alternative, the string array containing sUnInstallString... can be passed as a parameter within the above fixture, albeit the return type as array appears to fit a little better.

Answer 1

The GetUninstallString is used twice in the code.
In IsUpgrade
and in UnInstallOldVersion.
In IsUpgrade it's only tested for non-empty value.
In UnInstallOldVersion it is executed.
So make the function return whole UninstallString as a simple string.
For IsUpgrade it is enough.
And do the actual parsing to program path and its arguments in the UnInstallOldVersion only.
Also you should:
Handle a situation where there's no space in the string (no parameters)
The path to the uninstaller can contain spaces too (and it typically will as the uninstallers tend to be in Program Files).