Import selfmade Sage modules and functions into Sage script?
Update Jan 2020: E.M. Bray suggests a more elegant solution in the comments, see: https://ask.sagemath.org/question/7867/importingsagefiles/?answer=48947#postid48947

Let’s say that I have created a bunch of Sage code  Sage functions etc.  that I wish to reuse by importing into various Sage scripts. In straight Python, one would put these functions into their own separate file and import them using the usual from foo import funcname as localfuncname
type procedure. It is unclear to me what the proper procedure for doing the same in Sage is  one can’t use the same syntax for a .sage
file, and for example attach('functions.sage')
and only works in interactive Sage and stomps local variables.
However after some Googling and experimentation, I have found one method that behaves in the way that I need: namely that local variables aren’t stomped, and Sagestyle syntax, like expressing a rational as a fraction, is preserved. I don’t know if this is the best way to do it, but it seems to be working, so I thought I’d share it.
First write functions.sage
as though it were a module file.
Then for the script where we want to use it (myscript.sage
), we preparse the Sage functions file into a Python file and copy it to a name that can be handled before importing it.
When run, myscript.sage
produces the following.
From the commandline
From an interactive session:
The script produces functions.py
, which looks like this:
It has been working out for me so far, but it seems a strange way to go about things. I’d welcome any commenters who know of a nicer way.
 Refs: Ask Sagemath.org