BUG: is_list_like returns True even if __iter__ raises an error

[mroeschke]

Pandas version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

In [1]: class MyClass:
   ...:     def __iter__(self):
   ...:         raise Exception("I'm not listlike")
   ...: 

In [2]: from pandas.core.dtypes import inference

In [3]: inference.is_list_like(MyClass())
Out[3]: True

Issue Description

c_is_list_like checks

        # equiv: `isinstance(obj, abc.Iterable)`
        getattr(obj, "__iter__", None) is not None and not isinstance(obj, type)

But an object can override __iter__ to raise and is_list_like will still report that the object is True

Expected Behavior

In [3]: inference.is_list_like(MyClass())
Out[3]: False

Installed Versions

Replace this line with the output of pd.show_versions()

[Shreesha3112]

Would like to work on this issue

[Shreesha3112]

A potential solution

_is_iter_allowed = getattr(obj, "__iter__", None)
if _is_iter_allowed :
    try:
        #invoke
         obj.__iter__()
        _is_iter_allowed = True
    except Exception:
        #keep it as None
        pass

#then update the return statement as
return (
        # equiv: `isinstance(obj, abc.Iterable)`
        _is_iter_allowed  is not None and not isinstance(obj, type) #change
        ............
        .........

    )

[twoertwein]

If the caller uses __iter__ = None instead of raising inside the method, it should work. Settings methods to None in child classes to indicate that the child class doesn't implement something seems to be common, e.g., __hash__ is set to None for list and np.ndarray

[jbrockmendel]

Handling bespoke types in is_list_like comes up a lot and runs up against attempts to optimize this often-used function. I wonder if the solution is to move away from it in favor of a handful of explicitly supported types e.g. isinstance(obj, (ndarray, EA, Index, Series, list))

[mroeschke]

For context, I ran into this while trying to make Series.str not iterable xref #54173. is_list_like (expectedly) checks that Series.str is not list like but defining __iter__ make it "list-like"

[ArchPh03nix]

take