Inno Setup - Setting DefaultDir using wildcard registry entry?

Question

I\'ve recently started using Inno Setup to try and create a simple .exe installer for a game modification.

I\'ve got the installer working fine for the most part, bu

Answer 1

You can assign value of a DefaultDirName directive through the [Code] section. For instance, the following pseudo-script shows how to query two string values in registry and return the first found to the DefaultDirName directive. If none of the queried registry values is found, a default constant value is returned:

[Setup]
AppName=My Program
AppVersion=1.5
DefaultDirName={code:GetDirName}

[Code]
function GetDirName(Value: string): string;
var          
  InstallPath: string;
begin
  // initialize default path, which will be returned when the following registry
  // key queries fail due to missing keys or for some different reason
  Result := '{pf}\Default Dir Name';
  // query the first registry value; if this succeeds, return the obtained value
  if RegQueryStringValue(HKLM, 'Software\Vendor\Application', 'First Key', InstallPath) then
    Result := InstallPath
  // otherwise the first registry key query failed, so...
  else
  // query the second registry value; if it succeeds, return the obtained value
  if RegQueryStringValue(HKLM, 'Software\Vendor\Application', 'Second Key', InstallPath) then
    Result := InstallPath;
end;

Answer 2

In addition to using [Code] as answered elsewhere, you can also nest registry constants:

DefaultDirName={reg:HKLM,Software\Vendor1\Application,InstallPath|{reg:HKLM,Software\Vendor2\Application,InstallPath|{pf}\DefaultInstallPath}}

This will use Vendor1's path if it exists; failing that it will try Vendor2's path, and only if it cannot find either of those will it fall back to some default value.