After many years of intending to do it, I finally downloaded the ISTool set of add-ons for Inno Setup. The objective is to take advantage of the ISPP (Inno Setup Preprocessor) to automate the assignment of version info and numbering to setup files and setup GUI messages. The docs are a bit sparse for ISPP, but I eventually figured it all out, and I'm now able to do this:

• Extract complete version info from the program executable.
• Use that info to create all relevant GUI messages and numbering for the installer.
• Specify file paths once, in the header of the file, and have the rest of the script automatically populated with the right paths.
• Also get company name, publisher, app URL etc. directly from the executable.

The main value of learning how to do this is that it will make updating the installer much quicker and simpler in future; once the executable has been rebuilt with a new version number, and as long as the version info in the file is complete, the installer will use it automatically and we'll be able to build a new installer for a new release without changing the Inno Setup script at all.

A further possible benefit for the future is that there is a download dll available for ISTool, which can be called from an installer to get files directly from the Internet. This provides the promise of releasing installers which only download files which are required or have changed, reducing server load. How practical this might be for the type and scale of applications we release remains to be seen.