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Use enums for constants #1743

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Merged
janiversen merged 11 commits into from
Aug 29, 2023
Merged

Use enums for constants #1743

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28de82e
use proper enums
Booplicate Aug 21, 2023
52117d3
rm dummy tests
Booplicate Aug 21, 2023
7283f3c
rm useless pylint suppression
Booplicate Aug 21, 2023
8e30301
Revert "rm dummy tests"
Booplicate Aug 23, 2023
6958071
force int/str representation
Booplicate Aug 23, 2023
391bcc5
pep8 style constants
Booplicate Aug 23, 2023
3fcdc81
add docstrings
Booplicate Aug 23, 2023
44cf07e
fix broken indents
Booplicate Aug 23, 2023
d1889b1
pep8 spacing
Booplicate Aug 23, 2023
be28670
Merge branch 'dev' into enums
Booplicate Aug 29, 2023
9e9e953
doc changes
Booplicate Aug 29, 2023
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31 changes: 6 additions & 25 deletions pymodbus/constants.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,11 +3,12 @@
This is the single location for storing default
values for the servers and clients.
"""
import enum

INTERNAL_ERROR = "Pymodbus internal error"


class ModbusStatus: # pylint: disable=too-few-public-methods
class ModbusStatus(int, enum.Enum):
"""These represent various status codes in the modbus protocol.

.. attribute:: Waiting
Expand Down Expand Up @@ -44,12 +45,8 @@ class ModbusStatus: # pylint: disable=too-few-public-methods
SlaveOn = 0xFF
SlaveOff = 0x00

def __init__(self):
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@janiversen janiversen Aug 24, 2023

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Why should we permit objects ? I do not see the need in contrary.

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@Booplicate Booplicate Aug 25, 2023

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Enum members are singletons by default, we don't need any special logic to guard them, Python handles that for us.

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@janiversen janiversen Aug 25, 2023 •
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It does not prohibit that I can assign the class to a variable and make changes, with unexpected results.

And as far as I know, if you instanciate the class you get a new set of class variables (elements of enum).

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@Booplicate Booplicate Aug 25, 2023 •
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And as far as I know, if you instanciate the class you get a new set of class variables (elements of enum).

Actually, I believe no, class variables are static. You can change them, but restricting __init__ won't prevent that anyway.

I think I should clarify, __init__ is used to initialise enum members, not the enum itself.

Enums are using metaclasses underneath. Say, if somebody does ModbusStatus(0xFFFF), they will get ModbusStatus.WAITING, because enum members are singletons.

"""Prohibit objects."""
raise RuntimeError(INTERNAL_ERROR)


class Endian: # pylint: disable=too-few-public-methods
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@janiversen janiversen Aug 22, 2023

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This should be replaced by the system constant.

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@Booplicate Booplicate Aug 23, 2023

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Not sure I understood, do you mean sys.byteorder?

class Endian(str, enum.Enum):
"""An enumeration representing the various byte endianness.

.. attribute:: Auto
Expand All @@ -73,12 +70,8 @@ class Endian: # pylint: disable=too-few-public-methods
Big = ">"
Little = "<"

def __init__(self):
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@janiversen janiversen Aug 24, 2023

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We should not permit to instantiate any constant class.

"""Prohibit objects."""
raise RuntimeError(INTERNAL_ERROR)


class ModbusPlusOperation: # pylint: disable=too-few-public-methods
class ModbusPlusOperation(int, enum.Enum):
"""Represents the type of modbus plus request.

.. attribute:: GetStatistics
Expand All @@ -95,12 +88,8 @@ class ModbusPlusOperation: # pylint: disable=too-few-public-methods
GetStatistics = 0x0003
ClearStatistics = 0x0004

def __init__(self):
"""Prohibit objects."""
raise RuntimeError(INTERNAL_ERROR)


class DeviceInformation: # pylint: disable=too-few-public-methods
class DeviceInformation(int, enum.Enum):
"""Represents what type of device information to read.

.. attribute:: Basic
Expand Down Expand Up @@ -132,12 +121,8 @@ class DeviceInformation: # pylint: disable=too-few-public-methods
Extended = 0x03
Specific = 0x04

def __init__(self):
"""Prohibit objects."""
raise RuntimeError(INTERNAL_ERROR)


class MoreData: # pylint: disable=too-few-public-methods
class MoreData(int, enum.Enum):
"""Represents the more follows condition.

.. attribute:: Nothing
Expand All @@ -151,7 +136,3 @@ class MoreData: # pylint: disable=too-few-public-methods

Nothing = 0x00
KeepReading = 0xFF

def __init__(self):
"""Prohibit objects."""
raise RuntimeError(INTERNAL_ERROR)
2 changes: 0 additions & 2 deletions test/sub_messages/test_mei_messages.py
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Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,6 @@ def test_read_device_information_encode(self):
)
result = handle.encode()
assert result == message
assert str(handle) == "ReadDeviceInformationResponse(1)"

dataset = {
0x00: "Company",
Expand Down Expand Up @@ -133,7 +132,6 @@ def test_read_device_information_encode_long(self):
)
result = handle.encode()
assert result == message
assert str(handle) == "ReadDeviceInformationResponse(1)"

def test_read_device_information_decode(self):
"""Test that the read device information response can decode"""
Expand Down