Redeclare function after plugin activation

Question

First question on Stack.

I made a wordpress theme for a school project and I have a problem that I can't resolve alone.

I made a theme that needs ACF (there are some call get_field() and the_field() inside. But when I activate my theme I got some errors if acf is not enable. So I decide to find a solution and made a condition inside my functions.php

    if (!function_exists('get_field')) {
    function get_field()
    {
        return;
    }
}

if (!function_exists('the_field')) {
    function the_field()
    {
        return;
    }
}

So I add http://tgmpluginactivation.com/ inside my theme too to tell users that ACF is required with the possibility to install from my theme.

All is right for installation but when I want to activate the plugin :

Fatal error: Cannot redeclare get_field() (previously declared....)

I know that I previously declared get_field() and the_field() in my functions. But now, is it possible to erase my previous declaration with new ACF functions ?

I check before on stack board but I didn't find anything :(

Thanks a lot !

Answer 1

Ok with helps it's working. So theme was ok in front of wordpress but wasn't able to load in the admin so we changed the previous condition by :

if (!function_exists('get_field') && !is_admin()) {
    function get_field()
    {
        return;
    }
    function the_field()
    {
        return;
    }
}

but same problem with activation in the admin and it was because I use acf in my functions.php too.

if (!empty(get_post(get_field('login', 'options')))) {

changed in :

if( get_option('login') ) {