environment.py 文件源码

def fail_for_missing_callable(string, name):
    msg = string % name
    if isinstance(name, Undefined):
        try:
            name._fail_with_undefined_error()
        except Exception as e:
            msg = '%s (%s; did you forget to quote the callable name?)' % (msg, e)
    raise TemplateRuntimeError(msg)