GD0103: The exported member is read-only
========================================

====================================  ======================================
                                      Value
====================================  ======================================
**Rule ID**                           GD0103
**Category**                          Usage
**Fix is breaking or non-breaking**   Non-breaking
**Enabled by default**                Yes
====================================  ======================================

Cause
-----

A read-only member is annotated with the ``[Export]`` attribute. Read-only members
can't be exported.

Rule description
----------------

Godot doesn't allow exporting read-only members.

.. code-block:: csharp

    // Read-only fields can't be exported.
    [Export]
    public readonly int invalidField;

    // This field can be exported because it's not declared 'readonly'.
    [Export]
    public int validField;

    // Read-only properties can't be exported.
    [Export]
    public int InvalidProperty { get; }

    // This property can be exported because it has both a getter and a setter.
    [Export]
    public int ValidProperty { get; set; }

How to fix violations
---------------------

To fix a violation of this rule for fields, remove the ``readonly`` keyword or
remove the ``[Export]`` attribute.

To fix a violation of this rule for properties, make sure the property declares
both a getter and a setter, or remove the ``[Export]`` attribute.

When to suppress warnings
-------------------------

Do not suppress a warning from this rule. Read-only members can't be exported so
they will be ignored by Godot, resulting in runtime errors.