Mamushi

Mamushi is a fork of the popular Black formatter adapted to the Vyper programming language. Mamushi reformats your Vyper contracts in a readable and consistent way.

Installation

pip install mamushi

Usage

Search all *.vy files and overwrite them after formatting:

mamushi

Specify a list of *.vy files or directories and output to console after formatting:

mamushi [SRC]

Output the result to console instead of overwriting:

mamushi --in-place False

pre-commit

Add to your .pre-commit-config.yaml:

repos:
  - repo: https://github.com/benber86/mamushi
    rev: main
    hooks:
      - id: mamushi
        args: [ --line-length=100 ]

Notes

Line length

The default line length is 80. Line length can be adjusted by using the --line-length option.

AST Safety

By default, mamushi will compare the AST of your reformatted code with that of the original to ensure that the changes applied remain strictly formal. The option can be disabled with --safe False to speed things up.

Trailing commas

When handling expressions split by commas, mamushi follows Black's default behavior.

Mamushi also uses Black's magic trailing comma to give user the option to collapse a comma-separated expression into one line if possible. If a trailing comma is added, mamushi will always explode the expression. This can have important consequences for the commenting of your code. Consider the following two examples:

This code snippet:

self.b(0, # amount to send
       msg.sender, # sender
       True, # refund ?
        )

formats to the following with a trailing comma after the last argument (True):

self.b(
    0,  # amount to send
    msg.sender,  # sender
    True,  # refund ?
)

Disabling formatting

Mamushi supports # fmt: off and # fmt: on tags to disable formatting for specific regions of code:

x: uint256 = 1

# fmt: off
y:    uint256     =     2    # preserve this spacing
z:uint256=3
# fmt: on

a: uint256 = 4  # this will be formatted normally

The code between # fmt: off and # fmt: on will be preserved exactly as written, including all spacing and line breaks. These tags can be nested, and unclosed # fmt: off regions will extend to the end of the file.

You can also use # nosplit on individual lines to prevent line splitting while still applying spacing normalization:

assert not self.user[receiver][msg.sender], "Error message"  # nosplit

Note: # fmt: skip is not currently supported.

but if the trailing comma is removed, the line will be collapsed to:

self.b(0, msg.sender, True)  # amount to send  # sender  # refund ?

Future developments

• Multiprocessing when processing multiple files
• Configuration files
• Improve Windows compatibility
• Handle versioning of Vyper/lark grammar
• Refactoring comment handling in the parser
• Add .gitignore / exclude / include support