Compare commits

...

3 Commits

Author SHA1 Message Date
Sebastian Zumbrunn
04f68e935a fix after review 2024-11-13 14:53:00 +01:00
Sebastian Zumbrunn
1a20440092 write initial version of S7156 2024-11-12 15:18:52 +01:00
Seppli11
cbd6564edd Create rule S7156 2024-11-12 11:02:20 +00:00
3 changed files with 110 additions and 0 deletions

View File

@ -0,0 +1,2 @@
{
}

View File

@ -0,0 +1,23 @@
{
"title": "\"copy.replace\" should not be invoked with an unsupported argument",
"type": "CODE_SMELL",
"status": "ready",
"remediation": {
"func": "Constant/Issue",
"constantCost": "5min"
},
"tags": [],
"defaultSeverity": "Major",
"ruleSpecification": "RSPEC-7156",
"sqKey": "S7156",
"scope": "All",
"defaultQualityProfiles": ["Sonar way"],
"quickfix": "unknown",
"code": {
"impacts": {
"MAINTAINABILITY": "HIGH",
"RELIABILITY": "MEDIUM"
},
"attribute": "CONVENTIONAL"
}
}

View File

@ -0,0 +1,85 @@
:object_replacement_protocol: https://docs.python.org/3/library/copy.html#object.__replace__
This rule raises an issue when ``++copy.replace++`` is used on an incorrect type.
== Why is this an issue?
Python 3.13 introduced the function ``++copy.replace(obj, /, **changes)++`` which creates a new duplicate of the same type as ``++obj++`` then updating the values of the fields provided in ``++changes++``.
However, calling ``++copy.replace(...)++`` with an argument of an unsupported type will raise an ``++TypeError++``.
In order for a type to be supported by ``++copy.replace(...)++``, the {object_replacement_protocol}[replace protocol] must be implemented.
The following built-in types implement the {object_replacement_protocol}[replace protocol] and are thus supported by ``++copy.replace(...)++``
* ``++datetime.datetime++``, ``++datetime.date++``, ``++datetime.time++``
* ``++inspect.Signature++``, ``++inspect.Parameter++``
* ``++types.SimpleNamespace++``
* https://docs.python.org/3/library/typing.html#typing.NamedTuple[typed named tuples], ``++collections.namedtuple()++``
* https://docs.python.org/3/library/dataclasses.html[data classes]
* https://docs.python.org/3/reference/datamodel.html#code-objects[code objects]
=== Exceptions
This issue is only raised for Python 3.13 and above, since the respective method isn't available in previous versions of Python.
== How to fix it
If the argument passed to ``++copy.replace(...)++`` is a class defined in this project then, to fix the issue, implement the {object_replacement_protocol}[replace protocol] by defining the ``++__replace__++`` method in the class.
[source,python,diff-id=1,diff-type=compliant]
----
class SomeClass:
def __init__(self, name):
self.name = name
def __replace__(self, /, **changes):
return SomeClass(changes.get("name", self.name))
----
=== Code examples
==== Noncompliant code example
[source,python,diff-id=2,diff-type=noncompliant]
----
import copy
class AClass:
...
a = AClass()
b = copy.replace(a) # Noncompliant: AClass does not implement __replace__(...)
----
==== Compliant solution
[source,python,diff-id=2,diff-type=compliant]
----
import copy
class AClass:
...
def __replace__(self, /, **changes):
...
a = AClass()
b = copy.replace(a) # Compliant
@dataclass
class ADataClass:
...
c = ADataClass()
d = copy.replace(c) # Compliant
----
=== Pitfalls
Ensure that if the ``++__replace__++`` is implemented that the implementation creates a new object instead of updating the old one.
== Resources
=== Documentation
* Python Documentation - https://docs.python.org/3/library/copy.html#copy.replace[copy — Shallow and deep copy operations — copy.replace]
* Python Documentation - {object_replacement_protocol}[copy — Shallow and deep copy operations — object.\\__replace__]
* Python Documentation - https://docs.python.org/3/whatsnew/3.13.html#copy[What's New in Python 3.13]