| --- |
| layout: documentation |
| title: Variable x is read only |
| --- |
| |
| # Error: Variable x is read only |
| |
| A global variable cannot be reassigned. It will always point to the same object. |
| However, its content might change, if the value is mutable (for example, the |
| content of a list). Local variables don't have this restriction. |
| |
| ```python |
| a = [1, 2] |
| |
| a[1] = 3 |
| |
| b = 3 |
| |
| b = 4 # forbidden |
| ``` |
| |
| `ERROR: /path/ext.bzl:7:1: Variable b is read only` |
| |
| You will get a similar error if you try to redefine a function (function |
| overloading is not supported), for example: |
| |
| ```python |
| def foo(x): return x + 1 |
| |
| def foo(x, y): return x + y # forbidden |
| ``` |
