rspec/rules/S5755/python/rule.adoc

== Why is this an issue?

Accessing a non-existing member on an object will raise in most case an ``++AttributeError++`` exception.


This rule raises an issue when a non-existing member is accessed on a class instance and nothing indicates that this was expected.


=== Noncompliant code example

[source,python]
----
def access_attribute():
    x = 42
    return x.isnumeric()  # Noncompliant
----


=== Compliant solution

[source,python]
----
def access_attribute():
    x = "42"
    return x.isnumeric()
----


=== Exceptions

No issue will be raised:

* in ``++try ... except++`` blocks when ``++AttributeError++`` is caught.
* in ``++if hasattr(...)++`` blocks.
* when the accessed object has methods ``++__getattribute__++`` or ``++__getattr__++``. These methods will override the default attribute access behavior.
* when a class or its parent classes use ``++setattr++``. This can be used to add dynamically members to the class, even if it is not recommended.

You can also disable any issue for a given class by adding it to this rule's ignoredClassesForMemberValidation property.


== Resources

* https://youtu.be/NiSqG6s8skA[The Magic of Attribute Access - by Petr Viktorin - EuroPython Conference 2014]


ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Fix this access to a non-existing member "XXX"


=== Parameters

.ignoredClassesForMemberValidation
****

Comma-separated list of classes whose members will not be validated.
****


=== Highlighting

Primary: the member access

Secondary: the code giving us a clue on the type of the object whose member we try to access. Example: the assignment, the "if x is None" check...


endif::env-github,rspecator-view[]