07 Feb Ethereum: How do I import a package in vyper version 0.4.0^?

Importing Packages in Vyper 0.4.0

Vyper, a statically typed and compiled programming language for Solidity-based smart contracts on the Ethereum blockchain, supports importing external libraries and modules using the import directive.

In this article, we will show you how to import the snekmate package in Vyper version 0.4.0, focusing specifically on importing from the snekmate.tokens module.

The import directive

In Vyper, you can use the import directive to bring an external library or module into the scope of your contract. Here’s how you can do it:

from snekmate.tokens import ERC20 as base_token









Importing a function from the library
def get_snakemate_from_tokens():
return base_tokenERC20()

In this example, we define a function get_snekmate_from_tokens() that imports the ERC20 contract from the snakmate.tokens module and returns an instance of it.

Importing multiple libraries

To import multiple libraries or modules, you can use the following syntax:

from snekmate.tokens import ERC20 as base_token1
from snekmate.tokens import ERC20 as base_token2

Importing different functions from the library
def get_snakemate_from_tokens_1():
return base_token1ERC20()
def get_snakemate_from_tokens_2():
return base_token2ERC20()

Importing modules

To import a module, it must be in the lib directory of your project. In Vyper 0.4.0, lib is the default location for modules. You can use the following syntax:

from snekmate.tokens import ERC20 as base_token

Import a module from the library
from snekmate.tokens import ERC20, ERC7

Import all functions and variables from the module
for item in [ERC20, ERC721]:
exec(f"import {item}")

In this example, we assume there is a snakemate package with two modules: tokens and utils. We import both modules using the syntax above.

Include packages in contracts

To include packages in your contracts, you can simply add their directory to your lib list in Vyper’s build_config.py file. For example:

build_config
lib = [
'lib/snakemate',
]

This will tell Vyper to include the lib/snekmate package when compiling your contracts.

Conclusion

In this article, we showed how to import external libraries and modules in Vyper 0.4.0 using the import statement and multiple imports. We also showed how to include packages in your contracts by adding their directory to the lib list in build_config.py.