Utilities

All functions can be imported directly from the eth_utils module

Alternatively, you can get the curried version of the functions by importing them through the curried module like so:

>>> from eth_utils.curried import hexstr_if_str

ABI Utils

event_abi_to_log_topic(event_abi) -> bytes

Returns the 32 byte log topic for the given event abi.

>>> from eth_utils import event_abi_to_log_topic
>>> event_abi_to_log_topic({'type': 'event', 'anonymous': False, 'name': 'MyEvent', 'inputs': []})
b'M\xbf\xb6\x8bC\xdd\xdf\xa1+Q\xeb\xe9\x9a\xb8\xfd\xedb\x0f\x9a\n\xc21B\x87\x9aO\x19*\x1byR\xd2'

event_signature_to_log_topic(event_signature) -> bytes

Returns the 32 byte log topic for the given event signature.

>>> from eth_utils import event_signature_to_log_topic
>>> event_signature_to_log_topic('MyEvent()')
b'M\xbf\xb6\x8bC\xdd\xdf\xa1+Q\xeb\xe9\x9a\xb8\xfd\xedb\x0f\x9a\n\xc21B\x87\x9aO\x19*\x1byR\xd2'

function_abi_to_4byte_selector(function_abi) -> bytes

Returns the 4 byte function selector for the given function abi.

>>> from eth_utils import function_abi_to_4byte_selector
>>> function_abi_to_4byte_selector({'type': 'function', 'name': 'myFunction', 'inputs': [], 'outputs': []})
b'\xc3x\n:'

function_signature_to_4byte_selector(function_signature) -> bytes

Returns the 4 byte function selector for the given function signature.

>>> from eth_utils import function_signature_to_4byte_selector
>>> function_signature_to_4byte_selector('myFunction()')
b'\xc3x\n:'

Applicators

Applicators help you apply “formatters” in various ways, most notably:

  • apply formatters to values by key
  • apply formatters to lists by index
  • conditionally applying a formatter
  • conditionally applying one of several formatters.

Here we define a “formatter” as any callable that may be called with a single positional argument. It returns the “formatted” result. For example int() could be used as a formatter.

Defining your own formatter is easy:

def i_put_my_thing_down_flip_it_and_reverse_it(lyric):
    return ''.join(reversed(lyric))

These tools often work nicely when curried. Import them from the curried module to get that capability built in, like from eth_utils.curried import apply_formatter_if.

apply_formatter_if(condition, formatter, value) -> new_value

This function will apply the formatter only if bool(condition()) is True.

>>> from eth_utils.curried import apply_formatter_if, is_string

>>> bool_if_string = apply_formatter_if(is_string, bool)

>>> bool_if_string(1)
1
>>> bool_if_string('1')
True
>>> bool_if_string('')
False

apply_one_of_formatters(condition_formatter_pairs, value) -> new_value

This function will iterate through condition_formatter_pairs, and apply the first formatter which has a truthy condition. One of the formatters must match, or this function will raise a ValueError.

>>> from eth_utils.curried import apply_one_of_formatters, is_string, is_list_like

>>> multi_formatter = apply_one_of_formatters((
    (is_list_like, tuple),
    (is_string, i_put_my_thing_down_flip_it_and_reverse_it),
)
>>> multi_formatter('my thing')
'gniht ym'
>>> multi_formatter([1, 2])
(1, 2)
>>> multi_formatter(54)
ValueError("The provided value did not satisfy any of the formatter conditions")

apply_formatter_at_index(formatter, at_index, <list_like>) -> <new_list_like>

This function will apply the formatter to one element of list_like, at position at_index, and return a new iterable with that element replaced. The returned value will be the same type as the one passed into the third argument.

>>> from eth_utils.curried import apply_formatter_at_index

>>> targetted_formatter = apply_formatter_at_index(bool, 1)

>>> targetted_formatter((1, 2, 3))
(1, True, 3)

>>> targetted_formatter([1, 2, 3])
[1, True, 3]

apply_formatter_to_array(formatter, <list_like>) -> <new_list_like>

This function will apply the formatter to each element of list_like. It returns the same type as the list_like argument

>>> from eth_utils.curried import apply_formatter_to_array

>>> map_int = apply_formatter_to_array(int)

>>> map_int((1.2, 3.4, 5.6))
(1, 3, 5)

>>> map_int([1.2, 3.4, 5.6])
[1, 3, 5]

apply_formatters_to_sequence(formatters, <list_like>) -> <new_list_like>

This function will apply each formatter at to the list-like value, at the position it was supplied. It returns the same time as the list_like argument. For example:

>>> from eth_utils.curried import apply_formatters_to_sequence

>>> list_formatter = apply_formatters_to_sequence([bool, int, str])

>>> list_formatter([1.2, 3.4, 5.6])
[True, 3, '5.6']

>>> list_formatter((1.2, 3.4, 5.6))
(True, 3, '5.6')

# Formatters and list-like value must be the same length

>>> list_formatter((1.2, 3.4, 5.6, 7.8))
Traceback (most recent call last):
IndexError: Too few formatters for sequence: 3 formatters for (1.2, 3.4, 5.6, 7.8)

>>> list_formatter((1.2, 3.4))
Traceback (most recent call last):
IndexError: Too many formatters for sequence: 3 formatters for (1.2, 3.4)

combine_argument_formatters(*formatters) -> lambda <list_like>: <new_list_like>

DEPRECATED

You can replace all current versions of:

>>> from eth_utils import combine_argument_formatters

>>> list_formatter = combine_argument_formatters(bool, int, str)

With the newer, preferred:

>>> from eth_utils.curried import apply_formatters_to_sequence

>>> list_formatter = apply_formatters_to_sequence((bool, int, str))

The old usage works like:

Combine several formatters to be applied to a list-like value, each formatter at the position it was supplied. The new formatter will return the same type as it was supplied. For example:

>>> from eth_utils import combine_argument_formatters

>>> list_formatter = combine_argument_formatters(bool, int, str)

>>> list_formatter([1.2, 3.4, 5.6])
[True, 3, '5.6']

>>> list_formatter((1.2, 3.4, 5.6))
(True, 3, '5.6')

# it will pass through items longer than the number of formatters supplied
>>> list_formatter((1.2, 3.4, 5.6, 7.8))
(True, 3, '5.6', 7.8)

apply_formatters_to_dict(formatter_dict, <dict_like>) -> dict

This function will apply the formatter to the element with the matching key in dict_like, passing through values with keys that have no matching formatter.

>>> from eth_utils.curried import apply_formatters_to_dict

>>> dict_formatter = apply_formatters_to_dict({
...    'should_be_int': int,
...    'should_be_bool': bool,
... })

>>> result = dict_formatter({
...    'should_be_int': 1.2,
...    'should_be_bool': 3.4,
...    'pass_through': 5.6,
... })
>>> result == {'should_be_int': 1, 'should_be_bool': True, 'pass_through': 5.6}
True

apply_key_map(formatter_dict, <dict_like>) -> dict

This function will rename keys from using the lookups provided in formatter_dict. It will pass through any unspecified keys.

>>> from eth_utils.curried import apply_key_map

>>> dict_key_map = apply_key_map({
...    'black': 'orange',
...    'Internet': 'Ethereum',
... })

>>> result = dict_key_map({
...    'black': 1.2,
...    'Internet': 3.4,
...    'pass_through': 5.6,
... })
>>> result == {'orange': 1.2, 'Ethereum': 3.4, 'pass_through': 5.6}
True

Address Utils

is_address(value) -> bool

Returns True if the value is one of the following accepted address formats.

  • 20 byte hexadecimal, upper/lower/mixed case, with or without 0x prefix:
    • 'd3cda913deb6f67967b99d67acdfa1712c293601'
    • '0xd3cda913deb6f67967b99d67acdfa1712c293601'
    • '0xD3CDA913DEB6F67967B99D67ACDFA1712C293601'
    • '0xd3CdA913deB6f67967B99D67aCDFa1712C293601'
  • 20 byte hexadecimal padded to 32 bytes with null bytes, upper/lower/mixed case, with or without 0x prefix:
    • '000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601'
    • '000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601'
    • '0x000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601'
    • '0x000000000000000000000000D3CDA913DEB6F67967B99D67ACDFA1712C293601'
    • '0x000000000000000000000000d3CdA913deB6f67967B99D67aCDFa1712C293601'
  • 20 text or bytes string:
    • '\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01'

This function has two special cases when it will return False:

  • a 20-byte hex string that has mixed case, with an invalid checksum
  • a 32-byte value that is all null bytes
>>> from eth_utils import is_address
>>> is_address('d3cda913deb6f67967b99d67acdfa1712c293601')
True
>>> is_address('0xd3cda913deb6f67967b99d67acdfa1712c293601')
True
>>> is_address('0xD3CDA913DEB6F67967B99D67ACDFA1712C293601')
True
>>> is_address('0xd3CdA913deB6f67967B99D67aCDFa1712C293601')
True
>>> is_address('000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_address('000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_address('0x000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_address('0x000000000000000000000000D3CDA913DEB6F67967B99D67ACDFA1712C293601')
False
>>> is_address('0x000000000000000000000000d3CdA913deB6f67967B99D67aCDFa1712C293601')
False
>>> is_address(b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01')
True
>>> is_address('\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01')
False
>>> is_address('0x0000000000000000000000000000000000000000000000000000000000000000')
False
>>> is_address('\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
False

is_hex_address(value) -> bool

Return True if the value is a 20 byte hexadecimal encoded string in any of upper/lower/mixed casing, with or without the 0x prefix. Otherwise return False

  • 'd3cda913deb6f67967b99d67acdfa1712c293601'
  • '0xd3cda913deb6f67967b99d67acdfa1712c293601'
  • '0xD3CDA913DEB6F67967B99D67ACDFA1712C293601'
  • '0xd3CdA913deB6f67967B99D67aCDFa1712C293601'
>>> from eth_utils import is_hex_address
>>> is_hex_address('d3cda913deb6f67967b99d67acdfa1712c293601')
True
>>> is_hex_address('0xd3cda913deb6f67967b99d67acdfa1712c293601')
True
>>> is_hex_address('0xD3CDA913DEB6F67967B99D67ACDFA1712C293601')
True
>>> is_hex_address('0xd3CdA913deB6f67967B99D67aCDFa1712C293601')
True
>>> is_hex_address('000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_hex_address('000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_hex_address('0x000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_hex_address('0x000000000000000000000000D3CDA913DEB6F67967B99D67ACDFA1712C293601')
False
>>> is_hex_address('0x000000000000000000000000d3CdA913deB6f67967B99D67aCDFa1712C293601')
False
>>> is_hex_address('\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01')
False
>>> is_hex_address('\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01')
False
>>> is_hex_address('0x0000000000000000000000000000000000000000000000000000000000000000')
False
>>> is_hex_address('\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
False

is_binary_address(value) -> bool

Return True if the value is a 20 byte string.

>>> from eth_utils import is_binary_address
>>> is_binary_address('d3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_binary_address('0xd3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_binary_address('0xD3CDA913DEB6F67967B99D67ACDFA1712C293601')
False
>>> is_binary_address('0xd3CdA913deB6f67967B99D67aCDFa1712C293601')
False
>>> is_binary_address('000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_binary_address('000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_binary_address('0x000000000000000000000000d3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_binary_address('0x000000000000000000000000D3CDA913DEB6F67967B99D67ACDFA1712C293601')
False
>>> is_binary_address('0x000000000000000000000000d3CdA913deB6f67967B99D67aCDFa1712C293601')
False
>>> is_binary_address(b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01')
True
>>> is_binary_address('\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01')
False
>>> is_binary_address('0x0000000000000000000000000000000000000000000000000000000000000000')
False
>>> is_binary_address('\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
False

is_canonical_address(value) -> bool

Returns True if the value is an address in its canonical form.

The canonical representation of an address according to eth_utils is a 20 byte long string of bytes, eg: b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01'

>>> from eth_utils import is_canonical_address
>>> is_canonical_address('0xd3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_canonical_address(b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01')
True
>>> is_canonical_address('\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01xd')
False

is_checksum_address(value) -> bool

Returns True if the value is a checksummed address as specified by ERC55

>>> from eth_utils import is_checksum_address
>>> is_checksum_address('0xd3CdA913deB6f67967B99D67aCDFa1712C293601')
True
>>> is_checksum_address('0xd3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_checksum_address('0xD3CDA913DEB6F67967B99D67ACDFA1712C293601')
False
>>> is_checksum_address('0x52908400098527886E0F7030069857D2E4169EE7')
True
>>> is_checksum_address('0xde709f2102306220921060314715629080e2fb77')
True

is_checksum_formatted_address(value) -> bool

Returns True if the value is formatted as an ERC55 checksum address.

>>> from eth_utils import is_checksum_formatted_address
>>> is_checksum_formatted_address('0xd3CdA913deB6f67967B99D67aCDFa1712C293601')
True
>>> is_checksum_formatted_address('0xd3cda913deb6f67967b99d67acdfa1712c293601')
False
>>> is_checksum_formatted_address('0xD3CDA913DEB6F67967B99D67ACDFA1712C293601')
False
>>> is_checksum_formatted_address('0x52908400098527886E0F7030069857D2E4169EE7')
False
>>> is_checksum_formatted_address('0xde709f2102306220921060314715629080e2fb77')
False

is_normalized_address(value) -> bool

Returns True if the value is an address in its normalized form.

The normalized representation of an address is the lowercased 20 byte hexadecimal format.

>>> from eth_utils import is_normalized_address
>>> is_normalized_address('0xd3CdA913deB6f67967B99D67aCDFa1712C293601')
False
>>> is_normalized_address('0xd3cda913deb6f67967b99d67acdfa1712c293601')
True
>>> is_normalized_address('0xD3CDA913DEB6F67967B99D67ACDFA1712C293601')
False
>>> is_normalized_address('0x52908400098527886E0F7030069857D2E4169EE7')
False
>>> is_normalized_address('0xde709f2102306220921060314715629080e2fb77')
True

is_same_address(a, b) -> bool

Returns True if both a and b are valid addresses according to the is_address function and that they are both representations of the same address.

>>> from eth_utils import is_same_address
>>> is_same_address('0xd3cda913deb6f67967b99d67acdfa1712c293601', '0xD3CDA913DEB6F67967B99D67ACDFA1712C293601')
True
>>> is_same_address('0xd3cda913deb6f67967b99d67acdfa1712c293601', '0xd3CdA913deB6f67967B99D67aCDFa1712C293601')
True
>>> is_same_address('0xd3cda913deb6f67967b99d67acdfa1712c293601', b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01')
True

to_canonical_address(value) -> bytes

Given any valid representation of an address return its canonical form.

>>> from eth_utils import to_canonical_address
>>> to_canonical_address('0xd3cda913deb6f67967b99d67acdfa1712c293601')
b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01'
>>> to_canonical_address('0xD3CDA913DEB6F67967B99D67ACDFA1712C293601')
b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01'
>>> to_canonical_address('0xd3CdA913deB6f67967B99D67aCDFa1712C293601')
b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01'
>>> to_canonical_address(b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01')
b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01'

to_checksum_address(value) -> text

Given any valid representation of an address return the checksummed representation.

>>> from eth_utils import to_checksum_address
>>> to_checksum_address('0xd3cda913deb6f67967b99d67acdfa1712c293601')
'0xd3CdA913deB6f67967B99D67aCDFa1712C293601'
>>> to_checksum_address('0xD3CDA913DEB6F67967B99D67ACDFA1712C293601')
'0xd3CdA913deB6f67967B99D67aCDFa1712C293601'
>>> to_checksum_address('0xd3CdA913deB6f67967B99D67aCDFa1712C293601')
'0xd3CdA913deB6f67967B99D67aCDFa1712C293601'
>>> to_checksum_address(b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01')
'0xd3CdA913deB6f67967B99D67aCDFa1712C293601'

to_normalized_address(value) -> text

Given any valid representation of an address return the normalized representation.

>>> from eth_utils import to_normalized_address
>>> to_normalized_address(b'\xd3\xcd\xa9\x13\xde\xb6\xf6yg\xb9\x9dg\xac\xdf\xa1q,)6\x01')  # raw bytes
'0xd3cda913deb6f67967b99d67acdfa1712c293601'
>>> to_normalized_address('c6d9d2cd449a754c494264e1809c50e34d64562b')  # hex encoded
'0xc6d9d2cd449a754c494264e1809c50e34d64562b'
>>> to_normalized_address('0xc6d9d2cd449a754c494264e1809c50e34d64562b')  # hex encoded
'0xc6d9d2cd449a754c494264e1809c50e34d64562b'
>>> to_normalized_address('0XC6D9D2CD449A754C494264E1809C50E34D64562B')  # cap-cased
'0xc6d9d2cd449a754c494264e1809c50e34d64562b'

Conversion Utils

These methods convert values using standard practices in the Ethereum ecosystem. For example, strings are encoded to binary using UTF-8.

Because there is no reliable way to distinguish between text and a hex-encoded bytestring, you must explicitly specify which of the two is being supplied when passing in a str.

Only supply one of the arguments:

to_bytes(<bytes/int/bool>, text=<str>, hexstr=<str>) -> bytes

Takes a variety of inputs and returns its bytes equivalent. Text gets encoded as UTF-8.

>>> from eth_utils import to_bytes
>>> to_bytes(0)
b'\x00'
>>> to_bytes(0x000F)
b'\x0f'
>>> to_bytes(b'')
b''
>>> to_bytes(b'\x00\x0F')
b'\x00\x0f'
>>> to_bytes(False)
b'\x00'
>>> to_bytes(True)
b'\x01'
>>> to_bytes(hexstr='0x000F')
b'\x00\x0f'
>>> to_bytes(hexstr='000F')
b'\x00\x0f'
>>> to_bytes(text='')
b''
>>> to_bytes(text='cowmö')
b'cowm\xc3\xb6'

to_hex(<bytes/int/bool>, text=<str>, hexstr=<str>) -> str

Takes a variety of inputs and returns it in its hexadecimal representation. It follows the rules for converting to hex in the JSON-RPC spec. Roughly, it leaves leading 0s on bytes input, and trims leading zeros on int input.

>>> from eth_utils import to_hex
>>> to_hex(0)
'0x0'
>>> to_hex(1)
'0x1'
>>> to_hex(0x0)
'0x0'
>>> to_hex(0x000F)
'0xf'
>>> to_hex(b'')
'0x'
>>> to_hex(b'\x00\x0F')
'0x000f'
>>> to_hex(False)
'0x0'
>>> to_hex(True)
'0x1'
>>> to_hex(hexstr='0x000F')
'0x000f'
>>> to_hex(hexstr='000F')
'0x000f'
>>> to_hex(text='')
'0x'
>>> to_hex(text='cowmö')
'0x636f776dc3b6'

to_int(<bytes/int/bool>, text=<str>, hexstr=<str>) -> int

Takes a variety of inputs and returns its integer equivalent.

>>> from eth_utils import to_int
>>> to_int(0)
0
>>> to_int(0x000F)
15
>>> to_int(b'\x00\x0F')
15
>>> to_int(False)
0
>>> to_int(True)
1
>>> to_int(hexstr='0x000F')
15
>>> to_int(hexstr='000F')
15

to_text(<bytes/int/bool>, text=<str>, hexstr=<str>) -> str

Takes a variety of inputs and returns its string equivalent. Text gets decoded as UTF-8.

>>> from eth_utils import to_text
>>> to_text(0x636f776dc3b6)
'cowmö'
>>> to_text(b'cowm\xc3\xb6')
'cowmö'
>>> to_text(hexstr='0x636f776dc3b6')
'cowmö'
>>> to_text(hexstr='636f776dc3b6')
'cowmö'
>>> to_text(text='cowmö')
'cowmö'

Crypto Utils

Because there is no reliable way to distinguish between text and a hex-encoded bytestring, you must explicitly specify which of the two is being supplied when passing in a str.

Only supply one of the arguments:

keccak(<bytes/int/bool>, text=<str>, hexstr=<str>) -> bytes

>>> from eth_utils import keccak
>>> keccak(text='')
b"\xc5\xd2F\x01\x86\xf7#<\x92~}\xb2\xdc\xc7\x03\xc0\xe5\x00\xb6S\xca\x82';{\xfa\xd8\x04]\x85\xa4p"

# A series of equivalent hash inputs:

>>> keccak(text='☢')
b'\x85\xe8\x07"\xeb\x93\r\xe9;\xcc\xa8{\xa5\xdf\xda\x89\n\xa12\x95\xae\xad.\xec\xc9\x0b\xb2\xd9z\x14\x93\x16'

>>> keccak(0xe298a2)
b'\x85\xe8\x07"\xeb\x93\r\xe9;\xcc\xa8{\xa5\xdf\xda\x89\n\xa12\x95\xae\xad.\xec\xc9\x0b\xb2\xd9z\x14\x93\x16'

>>> keccak(b'\xe2\x98\xa2')
b'\x85\xe8\x07"\xeb\x93\r\xe9;\xcc\xa8{\xa5\xdf\xda\x89\n\xa12\x95\xae\xad.\xec\xc9\x0b\xb2\xd9z\x14\x93\x16'

>>> keccak(hexstr='0xe298a2')
b'\x85\xe8\x07"\xeb\x93\r\xe9;\xcc\xa8{\xa5\xdf\xda\x89\n\xa12\x95\xae\xad.\xec\xc9\x0b\xb2\xd9z\x14\x93\x16'

Please Note - When using Python’s native hex literals, python converts the hex to an int, so leading 0 bytes are truncated. But all other formats maintain zeros on the left. Hex literals are only padded until a whole number of bytes are provided to keccak. For example:

>>> keccak(0xe298a2)
b'\x85\xe8\x07"\xeb\x93\r\xe9;\xcc\xa8{\xa5\xdf\xda\x89\n\xa12\x95\xae\xad.\xec\xc9\x0b\xb2\xd9z\x14\x93\x16'

>>> keccak(0x0e298a2)
b'\x85\xe8\x07"\xeb\x93\r\xe9;\xcc\xa8{\xa5\xdf\xda\x89\n\xa12\x95\xae\xad.\xec\xc9\x0b\xb2\xd9z\x14\x93\x16'

>>> keccak(0x00e298a2)
b'\x85\xe8\x07"\xeb\x93\r\xe9;\xcc\xa8{\xa5\xdf\xda\x89\n\xa12\x95\xae\xad.\xec\xc9\x0b\xb2\xd9z\x14\x93\x16'

>>> keccak(0x000e298a2)
b'\x85\xe8\x07"\xeb\x93\r\xe9;\xcc\xa8{\xa5\xdf\xda\x89\n\xa12\x95\xae\xad.\xec\xc9\x0b\xb2\xd9z\x14\x93\x16'

>>> keccak(hexstr='0x0e298a2')
b'i\x0f$\xbd\xbe\xf7c\xbb\xb9M\xd9\x12H"\x9f\x1f\x87\\E\xa36\xc2\xea,\x8f.\r\xf5\x95\xdc\x19\x9b'

>>> keccak(hexstr='0x00e298a2')
b'i\x0f$\xbd\xbe\xf7c\xbb\xb9M\xd9\x12H"\x9f\x1f\x87\\E\xa36\xc2\xea,\x8f.\r\xf5\x95\xdc\x19\x9b'

>>> keccak(hexstr='0x000e298a2')
b'!$Ezy\xdeU<\xec\x1f\xd1\x10\x05\xff\x11\xfc=J\xcf\xd5H\x0f\xb3c\xcc\xb5\xae\xb1\x1eA\x8b\xd3'

Currency Utils

denoms

Object with property access to all of the various denominations for ether. Available denominations are:

denomination amount in wei
wei 1
kwei 1000
babbage 1000
femtoether 1000
mwei 1000000
lovelace 1000000
picoether 1000000
gwei 1000000000
shannon 1000000000
nanoether 1000000000
nano 1000000000
szabo 1000000000000
microether 1000000000000
micro 1000000000000
finney 1000000000000000
milliether 1000000000000000
milli 1000000000000000
ether 1000000000000000000
kether 1000000000000000000000
grand 1000000000000000000000
mether 1000000000000000000000000
gether 1000000000000000000000000000
tether 1000000000000000000000000000000
>>> from eth_utils import denoms
>>> denoms.wei
1
>>> denoms.finney
1000000000000000
>>> denoms.ether
1000000000000000000

to_wei(value, denomination) -> integer

Converts value in the given denomination to its equivalent in the wei denomination.

>>> from eth_utils import to_wei
>>> to_wei(1, 'ether')
1000000000000000000

from_wei(value, denomination) -> decimal.Decimal

Converts the value in the wei denomination to its equivalent in the given denomination. Return value is a decimal.Decimal with the appropriate precision to be a lossless conversion.

>>> from eth_utils import from_wei
>>> from_wei(1000000000000000000, 'ether')
Decimal('1')
>>> from_wei(123456789, 'ether')
Decimal('1.23456789E-10')

Debug Utils

Generate environment info

At the shell:

$ python -m eth_utils

Python version:
3.5.3 (default, Nov 23 2017, 11:34:05)
[GCC 6.3.0 20170406]

Operating System: Linux-4.10.0-42-generic-x86_64-with-Ubuntu-17.04-zesty

pip freeze result:
bumpversion==0.5.3
cytoolz==0.9.0
flake8==3.4.1
ipython==6.2.1
pytest==3.3.2
virtualenv==15.1.0
... etc

Decorators

@combomethod

Decorates methods in a class that can be called as both an instance method or a @classmethod.

Use the decorator like so:

>>> from eth_utils import combomethod

>>> class Storage:
...    val = 1
...
...    @combomethod
...    def get(combo):
...        if isinstance(combo, type):
...            print("classmethod call")
...        elif isinstance(combo, Storage):
...            print("instance method call")
...        else:
...            raise TypeError("Unreachable, unless you really monkey around")
...        return combo.val
...

As usual, instances create their own copy on assignment.

>>> store = Storage()
>>> store.val = 2

>>> store.get()
instance method call
2

>>> Storage.get()
classmethod call
1

Encoding Utils

big_endian_to_int(value) -> integer

Returns value converted to an integer (from a big endian representation).

>>> from eth_utils import big_endian_to_int
>>> big_endian_to_int(b'\x00')
0
>>> big_endian_to_int(b'\x01')
1
>>> big_endian_to_int(b'\x01\x00')
256

int_to_big_endian(value) -> bytes

Returns value converted to the big endian representation.

>>> from eth_utils import int_to_big_endian
>>> int_to_big_endian(0)
b'\x00'
>>> int_to_big_endian(1)
b'\x01'
>>> int_to_big_endian(256)
b'\x01\x00'

Functional Utils

compose(*callables) -> callable

DEPRECATED in 0.3.0.

Returns a single function which is the composition of the given callables.

>>> def f(v):
...     return v * 3
...
>>> def g(v):
...     return v + 2
...
>>> def h(v):
...     return v % 5
...
>>> compose(f, g, h)(1)
0
>>> h(g(f(1)))
0
>>> compose(f, g, h)(2)
3
>>> h(g(f(1)))
3
>>> compose(f, g, h)(3)
1
>>> h(g(f(1)))
1
>>> compose(f, g, h)(4)
4
>>> h(g(f(1)))
4

flatten_return(callable) -> callable() -> tuple

Decorator which performs a non-recursive flattening of the return value from the given callable.

>>> flatten_return(lambda: [[1, 2, 3], [4, 5], [6]])
(1, 2, 3, 4, 5, 6)

sort_return(callable) => callable() -> tuple

Decorator which sorts the return value from the given callable.

>>> flatten_return(lambda: [[1, 2, 3], [4, 5], [6]])
(1, 2, 3, 4, 5, 6)

reversed_return(callable) => callable() -> tuple

Decorator which reverses the return value from the given callable.

>>> reversed_return(lambda: [1, 5, 2, 4, 3])
(3, 4, 2, 5, 1)

to_dict(callable) => callable() -> dict

Decorator which casts the return value from the given callable to a dictionary.

>>> from eth_utils import to_dict
>>> @to_dict
... def build_thing():
...     yield 'a', 1
...     yield 'b', 2
...     yield 'c', 3
...
>>> build_thing() == {'a': 1, 'b': 2, 'c': 3}
True

to_list(callable) => callable() -> list

Decorator which casts the return value from the given callable to a list.

>>> from eth_utils import to_list
>>> @to_list
... def build_thing():
...     yield 'a'
...     yield 'b'
...     yield 'c'
...
>>> build_thing()
['a', 'b', 'c']

to_ordered_dict(callable) => callable() -> collections.OrderedDict

Decorator which casts the return value from the given callable to an ordered dictionary of type collections.OrderedDict.

>>> from eth_utils import to_ordered_dict
>>> @to_ordered_dict
... def build_thing():
...     yield 'd', 4
...     yield 'a', 1
...     yield 'b', 2
...     yield 'c', 3
...
>>> build_thing()
OrderedDict([('d', 4), ('a', 1), ('b', 2), ('c', 3)])

to_tuple(callable) => callable() -> tuple

Decorator which casts the return value from the given callable to a tuple.

>>> from eth_utils import to_tuple
>>> @to_tuple
... def build_thing():
...     yield 'a'
...     yield 'b'
...     yield 'c'
...
>>> build_thing()
('a', 'b', 'c')

to_set(callable) => callable() -> set

Decorator which casts the return value from the given callable to a set.

>>> from eth_utils import to_set
>>> @to_set
... def build_thing():
...     yield 'a'
...     yield 'b'
...     yield 'a'  # duplicate
...     yield 'c'
...
>>> build_thing() == {'c', 'b', 'a'}
True

apply_to_return_value(callable) => decorator_fn

This function takes a single callable and returns a decorator. The returned decorator, when applied to a function, will incercept the function’s return value, pass it to the callable, and return the value returned by the callable.

>>> from eth_utils import apply_to_return_value
>>> double = apply_to_return_value(lambda v: v * 2)
>>> @double
... def f(v):
...     return v
...
>>> f(2)
4
>>> f(3)
6

Hexidecimal Utils

add_0x_prefix(value) -> string

Returns value with a 0x prefix. If the value is already prefixed it is returned as-is. Value must be a string literal.

>>> from eth_utils import add_0x_prefix
>>> add_0x_prefix('12345')
'0x12345'
>>> add_0x_prefix('0x12345')
'0x12345'

decode_hex(value) -> bytes

Returns value decoded into a byte string. Accepts any string with or without the 0x prefix.

>>> from eth_utils import decode_hex
>>> decode_hex('0x123456')
b'\x124V'
>>> decode_hex('123456')
b'\x124V'

encode_hex(value) -> string

Returns value encoded into a hexadecimal representation with a 0x prefix

>>> from eth_utils import encode_hex
>>> encode_hex(b'\x01\x02\x03')
'0x010203'

is_0x_prefixed(value) -> bool

Returns True if value has a 0x prefix. Value must be a string literal.

>>> from eth_utils import is_0x_prefixed
>>> is_0x_prefixed('12345')
False
>>> is_0x_prefixed('0x12345')
True

is_hex(value) -> bool

Returns True if value is a hexadecimal encoded string of text type.

>>> from eth_utils import is_hex
>>> is_hex('')
False
>>> is_hex('0x')
True
>>> is_hex('0X')
True
>>> is_hex('1234567890abcdef')
True
>>> is_hex('0x1234567890abcdef')
True
>>> is_hex('0x1234567890ABCDEF')
True
>>> is_hex('0x1234567890AbCdEf')
True
>>> is_hex('12345')  # odd length is ok
True
>>> is_hex('0x12345')  # odd length is ok
True
>>> is_hex('123456__abcdef')  # non hex characters
False

# invalid, will raise TypeError:
>>> is_hex(b'')
Traceback (most recent call last):
TypeError: is_hex requires text typed arguments.
>>> is_hex(b'0x')
Traceback (most recent call last):
TypeError: is_hex requires text typed arguments.
>>> is_hex(b'0X')
Traceback (most recent call last):
TypeError: is_hex requires text typed arguments.

remove_0x_prefix(value) -> string

Returns value with the 0x prefix stripped. If the value does not have a 0x prefix it is returned as-is. Value must be string literal.

>>> from eth_utils import remove_0x_prefix
>>> remove_0x_prefix('12345')
'12345'
>>> remove_0x_prefix('0x12345')
'12345'

Humanize Utils

humanize_seconds(seconds) -> string

Returns the provide number of seconds as a shorthand string.

>>> from eth_utils import humanize_seconds
>>> humanize_seconds(0)
'0s'
>>> humanize_seconds(1)
'1s'
>>> humanize_seconds(60)
'1m'
>>> humanize_seconds(61)
'1m1s'

humanize_hash(bytes) -> string

Returns the provided byte string, hex encoded (without a 0x prefix) with the middle segment replaced by an ellipsis, only showing the first and last four hexidecimal digits.

>>> from eth_utils import humanize_hash
>>> humanize_hash(bytes(range(32)))
 '0001..1e1f'

humanize_ipfs_uri(string) -> string

Returns the provided IPFS uri, with the middle segment of the hash replaced by an ellipsis, only showing the first and last four characters of the hash.

>>> from eth_utils import humanize_ipfs_uri
>>> humanize_ipfs_uri('ipfs://QmTKB75Y73zhNbD3Y73xeXGjYrZHmaXXNxoZqGCagu7r8u')
 'ipfs://QmTK..7r8u'

Logging Utils

class HasLogger

Classes which inherit from this class will have an instance of a logger available on the attribute logger

>>> from eth_utils import HasLogger
>>> class MyClass(HasLogger):
...     pass
...
>>> MyClass.logger.debug("This works")
>>> instance = MyClass()
>>> instance.logger.debug("This also works")

The name of the logger instance is derived from the __qualname__ for the class.

Warning

This class will not behave nicely with the standard library typing.Generic. If you need to create a Generic class then you’ll need to assign your logging instances manually.

class ExtendedDebugLogger

A subclass of logging.Logger which exposes a debug2 function which can be used to log a message at the DEBUG2 log level.

Note

This class works fine on its own but will produce cleaner logs if you make sure to call eth_utils.setup_DEBUG2_logging at least once before issuing any debug2 level logs.

class HasExtendedDebugLogger

Same as the HasLogger class except the logger it exposes is an instance of ExtendedDebugLogger

setup_DEBUG2_logging() -> None

Installs the DEBUG2 level to the standard library logging module which uses the numeric level of 8. This includes adding it to the known levels as well as providing a logging.DEBUG2 convenience property on the logging module.

This function is purely for convenience. You can use ExtendedDebugLogger without this, though your logs will be printed with the label 'Level 8'.

>>> from eth_utils import setup_DEBUG2_logging
>>> import logging
>>> logging.getLevelName(8)
'Level 8'
>>> setup_DEBUG2_logging()
>>> logging.getLevelName(8)
'DEBUG2'
>>> logging.DEBUG2
8

Note

This function is idempotent

class HasLoggerMeta

This is the metaclass which is responsible for adding the logger instance to the class. It exposes two additional APIs.

  • HasLoggerMeta.replace_logger_class(cls: logging.Logger)

    Returns a new metaclass which will use the provided logger class.

  • HasLoggerMeta.meta_compat(other: type)

    Returns a new metaclass that derives from both metaclasses. This is useful when working in conjunction with abc.ABC or typing.Generic.

Numeric Utils

clamp(lower_bound, upper_bound, value) -> result

Returns value clamped within the inclusive range defined by [lower_bound, upper_bound]. The value can be any number type that supports < and > comparisons against the provided bounds.

>>> from eth_utils import clamp
>>> clamp(5, 7, 4)
5
>>> clamp(5, 7, 5)
5
>>> clamp(5, 7, 6)
6
>>> clamp(5, 7, 7)
7
>>> clamp(5, 7, 8)
7

Type Utils

is_boolean(value) -> bool

Returns True if value is of type bool

>>> from eth_utils import is_boolean
>>> is_boolean(True)
True
>>> is_boolean(False)
True
>>> is_boolean(1)
False

is_bytes(value) -> bool

Returns True if value is a byte string or a byte array.

>>> from eth_utils import is_bytes
>>> is_bytes('abcd')
False
>>> is_bytes(b'abcd')
True
>>> is_bytes(bytearray((1, 2, 3)))
True

is_dict(value) -> bool

Returns True if value is a mapping type.

>>> from eth_utils import is_dict
>>> is_dict({'a': 1})
True
>>> is_dict([1, 2, 3])
False

is_integer(value) -> bool

Returns True if value is an integer

>>> from eth_utils import is_integer
>>> is_integer(0)
True
>>> is_integer(1)
True
>>> is_integer('1')
False
>>> is_integer(1.1)
False

is_list_like(value) -> bool

Returns True if value is a non-string sequence such as a sequence (such as a list or tuple).

>>> from eth_utils import is_list_like
>>> is_list_like('abcd')
False
>>> is_list_like([])
True
>>> is_list_like(tuple())
True

is_list(value) -> bool

Returns True if value is a non-string sequence such as a list.

>>> from eth_utils import is_list
>>> is_list('abcd')
False
>>> is_list([])
True
>>> is_list(tuple())
False

is_tuple(value) -> bool

Returns True if value is a non-string sequence such as a tuple.

>>> from eth_utils import is_tuple
>>> is_tuple('abcd')
False
>>> is_tuple([])
False
>>> is_tuple(tuple())
True

is_null(value) -> bool

Returns True if value is None

>>> from eth_utils import is_null
>>> is_null(None)
True
>>> is_null(False)
False

is_number(value) -> bool

Returns True if value is numeric

>>> from eth_utils import is_number
>>> is_number(1)
True
>>> is_number(1.1)
True
>>> is_number('1')
False
>>> from decimal import Decimal
>>> is_number(Decimal('1'))
True

is_string(value) -> bool

Returns True if value is of any string type.

>>> from eth_utils import is_string
>>> is_string('abcd')
True
>>> is_string(b'abcd')
True
>>> is_string(bytearray((1, 2, 3)))
True

is_text(value) -> bool

Returns True if value is a text string.

>>> from eth_utils import is_text
>>> is_text(u'abcd')
True
>>> is_text(b'abcd')
False
>>> is_text(bytearray((1, 2, 3)))
False