处理兼容问题
听说你为方法添加了新参数、更改了返回类型、更改了参数的类型或默认值，而现在自动测试却在抱怨兼容性问题？
我们应该避免破坏兼容性，但如果必须破坏，也有相应的系统来处理这种情况，使过渡尽可能顺畅。
实际案例
这些修改取自拉取请求 #88047，为 AStarGrid2D 等 AStar 类添加了新的路径选项。其中包含了对 core/math/a_star_grid_2d.h 中的这些方法的修改：
Vector<Vector2> get_point_path(const Vector2i &p_from, const Vector2i &p_to);
TypedArray<Vector2i> get_id_path(const Vector2i &p_from, const Vector2i &p_to);
修改后：
Vector<Vector2> get_point_path(const Vector2i &p_from, const Vector2i &p_to, bool p_allow_partial_path = false);
TypedArray<Vector2i> get_id_path(const Vector2i &p_from, const Vector2i &p_to, bool p_allow_partial_path = false);
这段代码的作用是在文件中添加兼容方法的绑定，应该放在代码的 protected 部分，通常放在 _bind_methods() 旁边即可：
#ifndef DISABLE_DEPRECATED
TypedArray<Vector2i> _get_id_path_bind_compat_88047(const Vector2i &p_from, const Vector2i &p_to);
Vector<Vector2> _get_point_path_bind_compat_88047(const Vector2i &p_from, const Vector2i &p_to);
static void _bind_compatibility_methods();
#endif
They should start with an _ to indicate that they are internal, and end with _bind_compat_ followed by the PR number
that introduced the change (88047 in this example). These compatibility methods need to be implemented in a dedicated file,
like core/math/a_star_grid_2d.compat.inc in this case:
/**************************************************************************/
/* a_star_grid_2d.compat.inc */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/**************************************************************************/
#ifndef DISABLE_DEPRECATED
#include "core/variant/typed_array.h"
TypedArray<Vector2i> AStarGrid2D::_get_id_path_bind_compat_88047(const Vector2i &p_from_id, const Vector2i &p_to_id) {
return get_id_path(p_from_id, p_to_id, false);
}
Vector<Vector2> AStarGrid2D::_get_point_path_bind_compat_88047(const Vector2i &p_from_id, const Vector2i &p_to_id) {
return get_point_path(p_from_id, p_to_id, false);
}
void AStarGrid2D::_bind_compatibility_methods() {
ClassDB::bind_compatibility_method(D_METHOD("get_id_path", "from_id", "to_id"), &AStarGrid2D::_get_id_path_bind_compat_88047);
ClassDB::bind_compatibility_method(D_METHOD("get_point_path", "from_id", "to_id"), &AStarGrid2D::_get_point_path_bind_compat_88047);
}
#endif // DISABLE_DEPRECATED
Unless the change in compatibility is complex, the compatibility method should call the modified method directly,
instead of duplicating that method. Make sure to match the default arguments for that method (in the example above this would be false).
该文件应当放置在原始文件旁，以 .compat.inc 结尾而不是 .cpp 和 .h。接下来，应当将该文件包含进需要添加兼容性方法的 .cpp 文件中，这样 core/math/a_star_grid_2d.cpp 就变成了这样：
#include "a_star_grid_2d.h"
#include "a_star_grid_2d.compat.inc"
#include "core/variant/typed_array.h"
Finally, the GDExtension API changes need to be recorded. To do this, first compile Godot on the master branch, and
then run it with the --dump-extension-api flag:
git switch master
scons
godot --dump-extension-api
This will create a file named extension_api.json in your current directory. Switch to your feature branch, recompile Godot,
and then run it with the --validate-extension-api flag followed by the path to the extension_api.json file you just generated:
git switch my-feature-branch
scons
godot --validate-extension-api /path/to/extension_api.json
This will generate some lines starting with Validate extension JSON like so:
Validate extension JSON: Error: Field 'classes/AStar2D/methods/get_id_path/arguments': size changed value in new API, from 2 to 3.
Validate extension JSON: Error: Field 'classes/AStar2D/methods/get_point_path/arguments': size changed value in new API, from 2 to 3.
Validate extension JSON: Error: Field 'classes/AStar3D/methods/get_id_path/arguments': size changed value in new API, from 2 to 3.
Validate extension JSON: Error: Field 'classes/AStar3D/methods/get_point_path/arguments': size changed value in new API, from 2 to 3.
Validate extension JSON: Error: Field 'classes/AStarGrid2D/methods/get_id_path/arguments': size changed value in new API, from 2 to 3.
Validate extension JSON: Error: Field 'classes/AStarGrid2D/methods/get_point_path/arguments': size changed value in new API, from 2 to 3.
注意
If you get a Hash changed error for a method, it means that the compatibility binding is missing or incorrect.
Such lines shouldn't be added to the validation file, but fixed by binding the proper compatibility method.
Make sure to double-check the following:
For the compatibility method (the one whose name ends with the PR number), the argument types, names, and default values must be identical to the version of the method from before your changes.
In
_bind_compatibility_methods(), argument names provided to theD_METHOD()macro inClassDB::bind_compatibility_method()must be identical to those from theClassDB::bind_method()call for the original method.
Add these lines, followed by a comment explaining what the API change was and the actions taken to prevent breakage, to a validation file named after the GitHub pull request ID and placed in the folder of the Godot version it would have broken compatibility for.
Since this example was for PR #88047, its file name would be GH-88047.txt, and because this was done during
the development of 4.3 (thus changing from 4.2), the file would be in the misc/extension_api_validation/4.2-stable/ folder.
See below for a complete example of such a file for this PR:
GH-88047
--------
Validate extension JSON: Error: Field 'classes/AStar2D/methods/get_id_path/arguments': size changed value in new API, from 2 to 3.
Validate extension JSON: Error: Field 'classes/AStar2D/methods/get_point_path/arguments': size changed value in new API, from 2 to 3.
Validate extension JSON: Error: Field 'classes/AStar3D/methods/get_id_path/arguments': size changed value in new API, from 2 to 3.
Validate extension JSON: Error: Field 'classes/AStar3D/methods/get_point_path/arguments': size changed value in new API, from 2 to 3.
Validate extension JSON: Error: Field 'classes/AStarGrid2D/methods/get_id_path/arguments': size changed value in new API, from 2 to 3.
Validate extension JSON: Error: Field 'classes/AStarGrid2D/methods/get_point_path/arguments': size changed value in new API, from 2 to 3.
Added optional "allow_partial_path" argument to get_id_path and get_point_path methods in AStar classes.
Compatibility methods registered.
And that's it! You might run into a bit more complicated cases, like rearranging arguments, changing return types, etc., but this covers the basics on how to use this system.
详情见拉取请求 #76446。