[Closed] MXS – How to split script in multiple files?

There are several approaches, including include(), filein() and simply splitting the source into a startup folder.
The include() command is a COMPILE-TIME statement which simply puts the sources together. It is almost equivalent to Copy&Paste source code from one file into another at compile time. So it is designed to do exactly what you want, but has one drawback – since it is used by the compiler and not at run time, you cannot use variables as names or any other computed file names. This can be a problem if you want to SWITCH which file will be loaded depending on some condition like what OS or Max build is running (32/64) or what version of Max etc.

The fileIn() does not have this limitation – it is a run time function and performs the same as MAXScript>Load Script menu item – it opens and evaluates the code. It also has a drawback – that code is ALWAYS evaluated in GLOBAL scope, whereas include() can concatenate files at any place and the included source becomes part of whatever scope it is placed in. Thus, if you have some global functions or a global struct of functions the rest of the script is using, you could split them into a separate files and load them all via fileIn().

The last approach would be to save the multiple files into startup folders (e.g. the global function definitions in Stdplugs\Stdscript and the UI code in UI\usermacros or \Scripts\Startup and let Max load them as it boots up. The drawback here is that you have less control over what is loaded when. The \Stdscripts and its subfolders will be loaded first, but you cannot tell which file will be loaded first within that folder, so predeclaring variables might be necessary.

Plase read the MAXScript Help on filein() and include() to see which one works for you…