Sigh, welcome to asynchronous programming and state changing beneath you.
if the pointer to the doc was freed in the meantime, DOC_VALID() usage would lead to memory access over invalid pointer.
Document objects are never freed, so you will never get an invalid pointer, so thats one less worry. So no need to check if its in the document array, it will be.
But since closed document objects are reused for a different file you are correct that simply testing `doc->valid` is not sufficient to ensure its the same document, that is what `doc->id` is for, it is unique for each opened file and `document_find_by_id()` should be used, then valid can be checked.
See [plugin API docs](https://www.geany.org/manual/reference/structGeanyData.html#a933a5623cf6d093...).
The exact semantics of this changed at one point (vague memory, it was a while ago) and I bet lots of plugins didn't get updated, and new plugin writers didn't RTF above documentation. :grin:
Using `document_get_current()` is fine, so long as the callback never assumes its the same document as last time it was called.
Also its not guaranteed that Geany callbacks "do the right thing" either, `document_find_by_id()` is only used twice in Geany. In particular when dialogs are run state may change, but I think most of Geany assumes it doesn't. On Gnome and clones its probably safe because it honours modality which prevents users from modifying state (eg closing a document with the dialog open) but other window managers (eg KDE) do not honour modality, search the issues if interested.