How to use the qface.helper.qtcpp.Filters.classPrefix function in qface

def enum_value_to_cppliteral(value, module_name):
    value = value.strip().rsplit('.', 1)[-1]
    return '{0}{1}Module::{2}'.format(Filters.classPrefix, upper_first(module_name), value)

def className(symbol):
        classPrefix = Filters.classPrefix
        return '{0}{1}'.format(classPrefix, symbol.name)

def return_type(symbol):
    """
    Return the type declaration for properties, handle camel case module name
    """
    prefix = Filters.classPrefix
    if symbol.type.is_enum or symbol.type.is_flag:
        return('{0}{1}Module::{2}'.format(prefix, upper_first(symbol.module.module_name), flag_type(symbol)))
    if symbol.type.is_void or symbol.type.is_primitive:
        if symbol.type.name == 'string':
            return 'QString'
        if symbol.type.name == 'var':
            return 'QVariant'
        if symbol.type.name == 'real':
            return 'qreal'
        return symbol.type.name
    elif symbol.type.is_list:
        nested = return_type(symbol.type.nested)
        return 'QVariantList'.format(nested)
    elif symbol.type.is_model:
        nested = symbol.type.nested
        if nested.is_primitive:

def parameter_type(symbol):
    """
    Return the parameter declaration for properties, handle camel case module name
    """
    prefix = Filters.classPrefix
    if symbol.type.is_enum or symbol.type.is_flag:
        return '{0}{1}Module::{2} {3}'.format(prefix, upper_first(symbol.module.module_name), flag_type(symbol), symbol)
    if symbol.type.is_void or symbol.type.is_primitive:
        if symbol.type.name == 'string':
            return 'const QString &{0}'.format(symbol)
        if symbol.type.name == 'var':
            return 'const QVariant &{0}'.format(symbol)
        if symbol.type.name == 'real':
            return 'qreal {0}'.format(symbol)
        return '{0} {1}'.format(symbol.type, symbol)
    elif symbol.type.is_list:
        nested = return_type(symbol.type.nested)
        return 'const QVariantList &{1}'.format(nested, symbol)
    elif symbol.type.is_model:
        nested = symbol.type.nested
        if nested.is_primitive:

from path import Path

from qface.generator import FileSystem, Generator
from qface.helper.qtcpp import Filters
from qface.watch import monitor
from qface.idl.domain import Module, Interface, Property, Parameter, Field, Struct
from qface.helper.generic import upper_first

from jinja2 import TemplateAssertionError
import inspect

here = Path(__file__).dirname()

log = logging.getLogger(__file__)

Filters.classPrefix = ''
currentQFaceSrcFile = ''

builtin_config = {}
IVI_DEFAULT_TEMPLATES = ['frontend', 'qmlplugin', 'backend_simulator', 'backend_qtro', 'server_qtro', 'server_qtro_simulator', 'test']

def jinjaTrace():
    """
    Collects all jinja template files and the line numbers from the current calltrace
    """
    frame = inspect.currentframe()
    infos = []
    while frame:
        template = frame.f_globals.get('__jinja_template__')
        if template is not None:
            infos.append((inspect.getsourcefile(frame), template.get_corresponding_lineno(frame.f_lineno)))
        frame = frame.f_back

def returnType(symbol):
        prefix = Filters.classPrefix
        t = symbol.type
        if t.is_enumeration:
            return '{0}::{0}Enum'.format(symbol.type)
        if symbol.type.is_void or symbol.type.is_primitive:
            if t.is_string:
                return 'QString'
            if t.is_var:
                return 'QVariant'
            if t.is_real:
                return 'qreal'
            if t.is_int:
                return 'int'
            if t.is_bool:
                return 'bool'
            if t.is_void:
                return 'void'