Forbid complex grammar in slice #3427
Description
Rule request
Allow only a name, constant, and attribute in slice args.
Thesis
Correct:
array[3:7]
array[start_index:end_index]
array[index.start:index.end]
Wrong:
array[my_dict["start_index"]:my_list[-1]]
array[start_index():index.end()]
Should be:
start_index = my_dict["start_index"]
end_index = my_list[-1]
new_array = array[start_index:end_index]
start_index = start_index()
end_index = index.end()
new_array = array[start_index:end_index]
Reasoning
Complex grammar are difficult to read and should be stored in separate vars.
It's really difficult to review such many dependent constructions:
new_array = array[my_dict[":"]::get_step()]
It might also be worth forbidding an attribute, but I don't think it's a complex grammar.
class Slice:
class MyArray:
start = 1
end = 1
new_array = array[Slice.MyArray.start:]
But not
new_array = array[Slice(arg_1).MyArray(arg_2, arg_3).start:]