Get custom attributes for each VRayRenderElement class type using vray "getAHint" similar to how V-Ray MEL procedure 'vrayAddRenderElementImpl' does it.

get_vray_render_element_attributes.py

from maya import cmds
import itertools

def get_render_element_attributes(name):
    """Get attributes for VRayRenderElement based on class type"""
        
    attrs = []
    for i in itertools.count():
        buffer = cmds.vray("getAHint", 
                           "RenderElement", 
                           name, 
                           "attribute_%s" % i)
        if not buffer:
            break
        attr = buffer[0]
        attrs.append(attr)
    return attrs
    
def get_render_element_attr_parameter(attr):
    return cmds.vray("getAHint",
                    "RenderElementAttribute",
                    attr,
                    "vray_parameter")

# Example usage
for attr in get_render_element_attributes("ExtraTexElement"):
    parameter = get_render_element_attr_parameter(attr)
    print("{0: <45} - {1}".format(attr, parameter))

Usage:

for attr in get_render_element_attributes("ExtraTexElement"):
    parameter = get_render_element_attr_parameter(attr)
    print("{0: <45} - {1}".format(attr, parameter))

Example output:

vray_name_extratex                            - [u'name']
vray_type_extratex                            - [u'type']
vray_texture_extratex                         - [u'texmap']
vray_float_texture_extratex                   - [u'texmap_float']
vray_int_texture_extratex                     - [u'texmap_int']
vray_considerforaa_extratex                   - [u'consider_for_aa']
vray_filtering_extratex                       - [u'filtering']
vray_affectmattes_extratex                    - [u'affect_matte_objects']
vray_explicit_name_extratex                   - None
vray_exclude_list_extratex                    - [u'exclude_list']
vray_exclude_list_as_inclusive_extratex       - [u'exclude_list_as_inclusive_set']
vray_force_32_bit_output                      - [u'force_32_bit_output']
vray_denoise_extratex                         - [u'denoise']
vray_force_lossless_compression               - [u'force_lossless_compression']

---

To do the same for all V-Ray Render Elements class types:

from maya import mel

for class_type in mel.eval("vrayRenderElements"):
    print("Class Type: %s" % class_type)
    for attr in get_render_element_attributes(class_type):
        parameter = get_render_element_attr_parameter(attr)
        print("\t{0: <45} - {1}".format(attr, parameter))