Usage of eval, exec, and ast.literal_eval

Are there practical usages of eval, exec, and ast.literal_eval? The only times that I have seen them in actual usage is if something like a python object is saved into a file and isn't pickled or anything else.

What would be some actual non-trivial use cases of using these functions? The only example I was able to find in the docs was:

>>> x = 1
>>> eval('x+1')
2

Solution

eval and exec are for dynamically executing simple Python expressions or more complex statements (respectively).

So, one practical example from the standard library, collections.namedtuple uses exec to dynamically define a __new__ method for the tuple subclass being returned:

# Create all the named tuple methods to be added to the class namespace

s = f'def __new__(_cls, {arg_list}): return _tuple_new(_cls, ({arg_list}))'
namespace = {'_tuple_new': tuple_new, '__name__': f'namedtuple_{typename}'}
# Note: exec() has the side-effect of interning the field names
exec(s, namespace)
__new__ = namespace['__new__']
__new__.__doc__ = f'Create new instance of {typename}({arg_list})'
if defaults is not None:
    __new__.__defaults__ = defaults

This sometimes makes sense, however, this is often abused by inexperience programmers to write unnecessarily dynamic code, e.g. dynamically creating a bunch of variables, when they should have used a list or a dict (or some other container) instead.