Debug support in fiddle?

先从主 README 和 issue 中描述的 Fiddle::Pointer 行为开始，然后将 Fiddle 调用可用的调试信息与 Ruby 的 caller 和堆栈跟踪进行比较。确定可执行的结果是改进诊断，还是记录调试指南；完成的标准是明确指定其中一条路径，并由测试或 README 更改提供支持。

kojix2 provides the fiddle-bindings for libui here:

https://github.com/kojix2/LibUI

Libui is very easy to use; I ported many of my ruby-gtk3 widgets already,
even though libui is quite limited compared to ruby-gtk3. Anyway, in my own
project i modify Fiddle::Pointer to fake-"simulate" OOP.

My biggest problem with fiddle so far is the debug-support. Due to doing
tons of mistakes I get lots of segfaults, and while it is fun to find out why,
in the long run I'd love to be able to more easily and quickly find the error
I did. But when things segfault, I don't seem to get good quality information.

If segfaults happen in ruby, then I often get the exact name, stack tracke
and call stack; and I can use caller(). With fiddle I do not seem to get the
same information or at the least not as much as I think may be useful.

Would it be possible to improve the debug support in fiddle in general?
Perhaps a better stack trace showing where errors happened, a bit
like how ruby does. Or perhaps I just don't know how to debug this,
in which case it would be nice if the main README could provide a
few helpful pointers. Please feel free to close this issue at any moment
in time - I understand that this may not be a trivial change but if anyone
finds some time in the future, keeping better debug-support would be
super-useful. Right now I seem to do random changes and hope for
the best. :D (See also kojix2' comment in regards to having to assign
to variables to avoid the GC terminate the program. Would be nice
if this could all become more transparent when working via ruby.)