代表的Vala语法？

Question

首先，来自/usr/share/vala/vapi/libarchive.vapi的一些定义

[CCode (cprefix="ARCHIVE_", lower_case_cprefix="archive_", cheader_filename = "archive.h")]
namespace Archive {...
[CCode (instance_pos = 1.9, cname="archive_open_callback")]
    public delegate int OpenCallback (Archive archive);
    ...
    [CCode (cname = "struct archive", free_function="archive_write_finish")]
    public class Write : Archive {...
            public Result open (
                    [CCode (delegate_target_pos = 0.9)] OpenCallback ocb,
                    [CCode (delegate_target_pos = 0.9)] WriteCallback rcb,
                    [CCode (delegate_target_pos = 0.9)] CloseCallback ccb
            );
    }
}

然后是我的代码

int mOpenCallback (Write archive)
{
    return Result.OK;
}

void foo(){...
Write archive = new Write();
archive.open(mOpenCallback,mWriteCallback,mCloseCallback);
...}

结果：错误：作业：无法转换mOpenCallback' to Archive.OpenCallback'

它出了什么问题？

然后我尝试了这个

namespace Archive {
int OpenCallback (Write archive)
{
    return Result.OK;
}
}

void foo(){...
Write archive = new Write();
archive.open(OpenCallback,mWriteCallback,mCloseCallback);
...}

但输出：Archive' already contains a definition for OpenCallback'

void foo(){...
Write archive = new Write();
Archive.OpenCallback t = mOpenCallback;
archive.open(t,mWriteCallback,mCloseCallback);
...}

输出错误：分配：无法转换foo.mOpenCallback' to Archive.OpenCallback'

Answer 1

mOpenCallback的参数类型为Write，而不是Archive，因此它与代理OpenCallback的类型不同。如果您期望Write，则应该从Archive执行投射以在您的回电中写入。