Question

I set environment variable in the registry using InnoSetup:

[Registry]
Root: HKLM; Subkey: "SYSTEM\CurrentControlSet\Control\Session Manager\Environment"; ValueType: string; ValueName: "MY_PROGRAM_HOME_DIR"; ValueData: "{app}"

But system cannot see this variable until I call SendMessage.

[Code]
procedure DeinitializeSetup();
begin
  // HWND_BROADCAST = $FFFF 
  // WM_SETTINGCHANGE = $001A
  SendMessage($FFFF, $001A, 0, Longint(PChar('Environment')));
end;

InnoSetup says:

… Column 60: Type mismatch

How do I correctly typecast PChar into Longint in InnoSetup script?

Answer 1

Use the ChangesEnvironment directive instead of doing the same from your script code. From the reference:

When set to yes, at the end of the installation Setup will notify
other running applications (notably Windows Explorer) that they should
reload their environment variables from the registry.

In InnoSetup, when you use the above directive, the following code is called inside:

SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, 0,
  LPARAM(PChar('Environment')), SMTO_ABORTIFHUNG, 5000, MsgResult);