Star imports¶
You're probably on this page because you just saw an error like this one:
marimo raises this error you attempt to use import *.
In this example, x was already defined, and the subsequent cell raised an
error when we tried to run it. In your case, perhaps your variable is a loop
variable (i), a dataframe (df), or a plot (fig, ax).
Why can't I use * imports?¶
Star imports are incompatible with marimo's git-friendly file format and reproducible reactive execution:
- marimo's Python file format stores code in functions, so notebooks can be imported as regular Python modules without executing all their code. But Python disallows
import *everywhere except at the top-level of a module. - Star imports would also silently add names to globals, which would be incompatible with reactive execution.
Even Python's official style guide discourages the use of import *, writing:
Wildcard imports (from
import *) should be avoided, as they make it unclear which names are present in the namespace, confusing both readers and many automated tools.
What do I get in return? By accepting this constraint on imports, marimo makes your notebooks:
- reproducible, with a well-defined execution order, no hidden state, and no hidden bugs;
- executable as a script;
- interactive with UI elements that work without callbacks;
- shareable as a web app, with far better performance that streamlit.
As a bonus, you'll find that you end up with cleaner, reusable code.
How do I fix this error?¶
Fixing this error is simple: just import the module, and use . notation
to access its members.
instead of