Overriding Context for bpy.ops.transform.shrink_fatten

Question

I can't seem to get sufficient context for calling bpy.ops.transform.shrink_flatten() without this error:

RuntimeError: Operator bpy.ops.transform.shrink_fatten.poll() failed, context is incorrect

I've attempted to specify the active object and some area parameters (via this answer),

# attempt to set obj-to-be-resized as active obj
bpy.context.scene.objects.active = obj_to_resize

context = bpy.context
override = context.copy()

for area in context.screen.areas:
    if area.type == 'VIEW_3D':
        override["area"] = area
        override["space_data"] = area.spaces.active
        override["region"] = area.regions[-1] # rule of thumb r.type == 'WINDOW'
        break

bpy.ops.transform.shrink_fatten(override, value=0.02)

but this isn't enough to avoid the error. I'm not sure which context parameters I'm still missing. Inspecting the source (line 947) gave me its polling function (line 373), ED_operator_editmesh, which checks the edit_object.

However, attempting to override this parameter by supplying override["edit_object"] = obj_to_resize produces a seg fault:

# backtrace
blender(BLI_system_backtrace+0x34) [0x561503952f54]
blender(+0xb7b882) [0x561502ede882]
/usr/lib/libc.so.6(+0x37e00) [0x7f060029ce00]
blender(BLI_addtail+0xc) [0x56150391cfac]
blender(ED_region_draw_cb_activate+0x39) [0x561502f04739]
blender(initTransform+0x8d3) [0x561503040e73]
blender(+0xcfd54c) [0x56150306054c]
blender(+0xcfd5ff) [0x5615030605ff]
blender(+0xb836ba) [0x561502ee66ba]
blender(WM_operator_call_py+0x6d) [0x561502ee6fed]
blender(+0xfab340) [0x56150330e340]
/usr/lib/libpython3.7m.so.1.0(_PyMethodDef_RawFastCallKeywords+0x148) [0x7f0605df31c8]
/usr/lib/libpython3.7m.so.1.0(_PyCFunction_FastCallKeywords+0x21) [0x7f0605df3461]
/usr/lib/libpython3.7m.so.1.0(_PyEval_EvalFrameDefault+0x4a75) [0x7f0605e62a75]
/usr/lib/libpython3.7m.so.1.0(_PyEval_EvalCodeWithName+0x2e9) [0x7f0605dac879]
/usr/lib/libpython3.7m.so.1.0(_PyFunction_FastCallDict+0x2fc) [0x7f0605dadadc]
/usr/lib/libpython3.7m.so.1.0(_PyObject_Call_Prepend+0x68) [0x7f0605dbd028]
/usr/lib/libpython3.7m.so.1.0(+0x16d3ef) [0x7f0605e0b3ef]
/usr/lib/libpython3.7m.so.1.0(_PyObject_FastCallKeywords+0x3ac) [0x7f0605e1f2fc]
/usr/lib/libpython3.7m.so.1.0(_PyEval_EvalFrameDefault+0x5d35) [0x7f0605e63d35]
/usr/lib/libpython3.7m.so.1.0(_PyFunction_FastCallKeywords+0x10b) [0x7f0605df2a3b]
/usr/lib/libpython3.7m.so.1.0(_PyEval_EvalFrameDefault+0x76d) [0x7f0605e5e76d]
/usr/lib/libpython3.7m.so.1.0(_PyEval_EvalCodeWithName+0x2e9) [0x7f0605dac879]
/usr/lib/libpython3.7m.so.1.0(PyEval_EvalCodeEx+0x44) [0x7f0605dad7a4]
/usr/lib/libpython3.7m.so.1.0(PyEval_EvalCode+0x1c) [0x7f0605dad7cc]
/usr/lib/libpython3.7m.so.1.0(+0x2381e4) [0x7f0605ed61e4]
/usr/lib/libpython3.7m.so.1.0(PyRun_FileExFlags+0x9e) [0x7f0605ed76ee]
blender(+0xf95b38) [0x5615032f8b38]
blender(+0xb79be5) [0x561502edcbe5]
blender(BLI_argsParse+0xd7) [0x561503908347]
blender(main+0x2e9) [0x561502ec5a39]
/usr/lib/libc.so.6(__libc_start_main+0xf3) [0x7f0600289223]
blender(_start+0x2e) [0x561502edb33e]

What context am I missing? And why does attempting to override edit_object cause a seg fault?

Answer 1

@batFINGER's comment is helpful: you (probably) can't override context for edit mode. I ended up just replacing the shrink_fatten operator with the equivalent function, per this:

def execute(self, context):

    ob = bpy.context.object
    me = ob.data
    bm = bmesh.from_edit_mesh(me)

    for v in bm.verts:
        if v.select:
            v.co += v.normal * self.factor

    bmesh.update_edit_mesh(me, True, False)
    return {'FINISHED'}

which was an order of magnitude easier and could be, in general, potentially the best way to replace relatively simple edit operations instead of overriding their context.