Inno Setup Preprocessor
Inno Setup Preprocessor (ISPP) is an preprocessor add-on for Inno Setup. ISPP does not depend on any particular version of these products. The only requirement is that version must be 1.3 or higher.
Inno Setup Preprocessor works at compile-time. It has nothing to do with the behaviour of setups.
The main purpose of ISPP is to automate some pre or post compilation tasks and decrease the probability of typos in your scripts. For example, you can declare ISPP variable (compile-time variable) – your application name, for instance – and then use its value in several places of your script. If for some reason you need to change the name of your application, you'll have to change it only once in your script. Without ISPP, you would probably need to change all occurences of your application name throughout the script (AppName, AppVerName, DefaultGroupName etc. [Setup] section directives).
Another example of using ISPP would be gathering version information from your application by reading the version info of an EXE file, and using it in AppVerName [Setup] section directive or anywhere else (for example, in [Code] section). Without ISPP, you would have to modify your script each time version of your application changes.
Conditional compilation (inclusion of parts of the script) is possible with ISPP, therefore, you can maintain only one script for different versions/levels of your installation packages (trial and fully functional, lite and enterpise, etc.).
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