Split code into multiple modules

Development
1

The following question has been asked on Telegram:

Hi, is it possible to split contracts into multiple modules and import them? I could keep them in single module but would like to split them and currently having issues with imports. I couldn’t find any examoles, only imports of utils module. Thanks in advance

2

Yes it is!

You can import modules within your file using the python import instruction.
For example, if your module a is in a file named module_a.py you can do

from module_a import a

In your test you need to add provide the full module list to the test scenario.

sc = sp.test_scenario([a, b, ...])

The list must be ordered based on the usage. For example, if module a is then used inside module b you provide [a, b].

You can then access the modules elements with module_name.element.

Here is a complete example with all modules in the same file. The only change if they are in multiple files is the import instruction.

import smartpy as sp

@sp.module
def a():
    t: type = sp.nat

    class Parent(sp.Contract):
        def __init__(self):
            pass

@sp.module
def b():
    class MyContract(a.Parent):
        def __init__(self, x):
            a.Parent.__init__(self)
            sp.cast(x, a.t)
            self.data.x = x

        @sp.entrypoint
        def ep(self):
            pass

if "main" in __name__:
    @sp.add_test(name="MyContract")
    def test():
        sc = sp.test_scenario([a, b])
        c1 = b.MyContract(5)
        sc += c1
        c1.ep()
3

Thanks for your reply Jordan.

I was trying that before and currently recreated your example and still having some issues with it. I have a folder named contracts. In this folder I have defined two files module_a.py and module_b.py.

module_a.py

import smartpy as sp

@sp.module
def a():
    t: type = sp.nat

    class Parent(sp.Contract):
        def __init__(self):
            pass

module_b.py

import smartpy as sp
from module_a import a

@sp.module
def b():
    class MyContract(a.Parent):
        def __init__(self, x):
            a.Parent.__init__(self)
            sp.cast(x, a.t)
            self.data.x = x

        @sp.entrypoint
        def ep(self):
            pass

if "main" in __name__:
    @sp.add_test(name="MyContract")
    def test():
        sc = sp.test_scenario([a, b])
        c1 = b.MyContract(5)
        sc += c1
        c1.ep()

When I try to test module_b.py using ./smartpy test contracts/module_b.py output I get an error ModuleNotFoundError: No module named 'module_a'. Am I missing something?

4

I’m able to replicate the error.
I’ll back to you when I have a fix.