Set variable name and value through Function - php

Question

Hallo I am trying to create a function with two arguments.
Argument ONE should set a variable name and Argument TWO sets the name of the custom field which is the value of the variable.
I need a function for this, because the variable should get its value from a custom field of different pages depending on
- if { it's parent has the ID 77, get its own field }
- else { if it's parent doesn't have the ID 77, get its parent field }
This is what I tried, but does not work yet:
function variable_is_field($variable, $field) {
global $post;
if($post->post_parent == 77) // if page parent ID=77
$variable = get_field($field);
else
$variable = get_field($field, $post->post_parent;);
}
variable_is_field("$my-variable1", "my-custom-field1");
echo $my-variable1;
Any idea what's wrong with the code?

Answer 1

i can propose 2 solutions
if you need it only on this scope and one time like comment suggested so the code will be:
function variable_is_field($field) {
global $post;
$variable = null;
if($post && $post->post_parent == 77) // if page parent ID=77
$variable = get_field($field);
else
$variable = get_field($field, $post->post_parent;);
return $variable ;
}
$my-variable1 = variable_is_field("my-custom-field1");
echo $my-variable1;
else if you need it globally you can try somenthing like dis
global $my-variable1;
function variable_is_field($field) {
global $post;
global $my-variable1;
if($post && $post->post_parent == 77) // if page parent ID=77
$my-variable1= get_field($field);
else
$my-variable1 = get_field($field, $post->post_parent;);
}
variable_is_field("my-custom-field1");
echo $my-variable1;
Hope that this can help.