protect function to be not overridden in ZSH - zsh

Question

I have a file where my ZSH functions are defined, and I source it from my zshrc.
There are the set of helper functions which used only in other functions from that file.
My question is how can I keep readable names for those helpers (such as 'ask', etc.) and be sure that they will not be overridden later in other sourced files.
So, for example I have two functions:
helper() {
# do something
}
function-i-want-to-use-in-shell() {
helper # call helper, I want to be sure that it is 'my' helper
# do something more
}
I want to protect helper for functions declared within that file.
It would be nice if I could wrap those functions in, for example, subshell () and then export function-i-want-to-use-in-shell to parent (I know this is impossible);
So I am looking for a convenient way to create something like their own scope for those functions, and make some of them global and some local.
[EDIT]
I think another example will give better explanation of the behaviour I want to achieve:
So, for second example I have two files: file1.sh and file2.sh.
file1.sh the same as example above, in file2.sh another function helper defined. I want you to understand that helper from file1.sh it's just function for local usage (within that file), just snippet of code. Later in shell I want only use function-i-want-to-use-in-shell from file1.sh and helper from file2.sh. I do not want helper readonly, I just want it for local usage only. Maybe I can do something like "namespace" for functions in file1.sh, or somehow achieve javascript-like scoping lookup behaviour in that file. The only way I see to do it now is to refuse the condition to keep good, readable, self-explaining names of my helper functions, and
give them names that are hardly to be invented by someone else, or use prefix for those functions. Oh, I just wanted to write something like if ask "question"; then but not if my-local-ask "question"; then in other my functions, and be sure that if someone (or I myself) will define later another function ask nothing will be broken

Answer 1

It's a little heavy-handed, but you can use an autoloaded function to, if not prevent overriding a function, "reset" it easily before calling. For example.
# Assumes that $func_dir is a directory in your fpath;
% echo 'print bar' > $func_dir/helper
% helper () { print 9; }
% helper
9
% unset -f helper
% autoload helper
% helper
bar