Function: frame-id
frame-id is a function defined in frame.c.
Signature
(frame-id &optional FRAME)
Documentation
Return FRAME's id.
If FRAME is nil, use the selected frame. Return nil if the id has not been set.
Probably introduced at or before Emacs version 31.1.
Source Code
// Defined in /usr/src/emacs/src/frame.c
{
struct frame *f = decode_live_frame (frame);
if (f->id == 0)
return Qnil;
else
return make_fixnum (f->id);
}