core-types.rst

Data Types

Brownie uses custom data types to simplify working with common represented values.

Wei

The Wei <brownie.convert.datatypes.Wei> class is used when a value is meant to represent an amount of Ether. It is a subclass of :pyint <int> capable of converting strings, scientific notation and hex strings into wei denominated integers:

>>> Wei("1 ether")
1000000000000000000
>>> Wei("12.49 gwei")
12490000000
>>> Wei("0.029 shannon")
29000000
>>> Wei(8.38e32)
838000000000000000000000000000000

It also converts other values to Wei <brownie.convert.datatypes.Wei> before performing comparisons, addition or subtraction:

>>> Wei(1e18) == "1 ether" True >>> Wei("1 ether") < "2 ether" True >>> Wei("1 ether") - "0.75 ether" 250000000000000000

Whenever a Brownie method takes an input referring to an amount of ether, the given value is converted to Wei <brownie.convert.datatypes.Wei>. Balances and uint/int values returned in contract calls and events are given in Wei <brownie.convert.datatypes.Wei>.

>>> accounts[0].balance()
100000000000000000000
>>> type(accounts[0].balance())
<class 'brownie.convert.Wei'>

Fixed

The Fixed <brownie.convert.datatypes.Fixed> class is used to handle Vyper decimal values. It is a subclass of :pydecimal.Decimal <decimal.Decimal> that allows comparisons, addition and subtraction against strings, integers and Wei <brownie.convert.datatypes.Wei>.

>>> Fixed(1)
Fixed('1')
>>> Fixed("3.1337")
Fixed('3.1337')
>>> Fixed("12.49 gwei")
Fixed('12490000000')
>>> Fixed("-1.23") == "-1.2300"
True

Attempting to assign, compare or perform arithmetic against a float raises a TypeError.

>>> Fixed(3.1337)
Traceback (most recent call last):
    File "<console>", line 1, in <module>
TypeError: Cannot convert float to decimal - use a string instead

>>> Fixed("-1.23") == -1.2300
Traceback (most recent call last):
    File "<console>", line 1, in <module>
TypeError: Cannot compare to floating point - use a string instead