Hi.
On 11.12.2013. 9:23, Johannes Schneider wrote:
can somebody explain me the difference between accessing attributes via
obj.attribute and getattr(obj, "attribute")?
Is there a special reason or advantage when using getattr?
You can not use obj.attribute if you have the word 'attribute' as a
string, e.g. if you read it from a configuration file.
Also, you can not test whether an object has an attribute when using
the object.attribute access method without raising/catching an exception
and then it can be hard to make sure no other code caused the exception.
But I suppose in most real-life cases both of the suggested access
methods are equivalent, since most of the time you really do not have
names of your attributes as strings and are free to simply assume the
attribute exists.
One example problem I had recently where I think you have to use
getattr(): list the names of all global references in the __builtins__
module and, a the type of object each of those references points to.
[Ran into this one by accident as a part of demonstrating to a new
Python student what names Python recognizes in some module, and what
names require additional imports.]
Hope this helps.
Best regards,
Jurko Gospodnetić
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