Re: [PATCH 4/5] gdb/python: rework how the disassembler API reads the result object

[Eli Zaretskii <eliz@gnu.org>]

> Cc: Andrew Burgess <aburgess@redhat.com>
> Date: Tue,  4 Apr 2023 09:21:06 +0100
> From: Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org>
> 
> This commit is a refactor ahead of the next change which will make
> disassembler styling available through the Python API.
> 
> Unfortunately, in order to make the styling support available, I think
> the easiest solution is to make a very small change to the existing
> API.
> 
> The current API relies on returning a DisassemblerResult object to
> represent each disassembled instruction.  Currently GDB allows the
> DisassemblerResult class to be sub-classed, which could mean that a
> user tries to override the various attributes that exist on the
> DisassemblerResult object.
> 
> This commit removes this ability, effectively making the
> DisassemblerResult class final.
> 
> Though this is a change to the existing API, I'm hoping this isn't
> going to cause too many issues:
> 
>   - The Python disassembler API was only added in the previous release
>     of GDB, so I don't expect it to be widely used yet, and
> 
>   - It's not clear to me why a user would need to sub-class the
>     DisassemblerResult type, I allowed it in the original patch
>     because at the time I couldn't see any reason to NOT allow it.
> 
> Having prevented sub-classing I can now rework the tail end of the
> gdbpy_print_insn function; instead of pulling the results out of the
> DisassemblerResult object by calling back into Python, I now cast the
> Python object back to its C++ type (disasm_result_object), and access
> the fields directly from there.  In later commits I will be reworking
> the disasm_result_object type in order to hold information about the
> styled disassembler output.
> 
> The tests that dealt with sub-classing DisassemblerResult have been
> removed, and a new test that confirms that DisassemblerResult can't be
> sub-classed has been added.
> ---
>  gdb/NEWS                               |  3 ++
>  gdb/doc/python.texi                    |  2 +
>  gdb/python/py-disasm.c                 | 54 +++++++-------------------
>  gdb/testsuite/gdb.python/py-disasm.exp | 15 +++++--
>  gdb/testsuite/gdb.python/py-disasm.py  | 37 ------------------
>  5 files changed, 31 insertions(+), 80 deletions(-)

OK for the documentation parts.  Thanks.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>