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There are multiple issues wiht YAML loading.
1. Jinja2 renders None values as a string 'None'. This is not valid YAML
we need to render None values to '~' or 'null' which is the native YAML
None value.
2. Jinja2 renders dict and lists that contain unicode with
u'foo' values. This is not value YAML syntax.
Because we are serializing dict and lists into YAML, we
need to encode them as valid YAML. We can override Jinja2 finalize to
use yaml.dump to dump inline YAML.
We use yaml.safe_dump(elem, default_flow_style=True).replace('\n', '')
to generate valid single-line YAML dict and list values.
But this problem highlights the general difficulties with templating and
loading files.
We could avoid this Python->Jinja2->YAML->Python issue by directly
injecting the list or dict after the YAML is loaded.
I'm not sure of the real utility of these templates.
3. On Python 2 YAML loader is rendering all strings
as unicode. This does not work for Trex because Trex is broken
and badly coded. Trex does type checking against str() which
is different for Python 2 and Python 3.
The default YAML loader will return native string types, str() or unicode()
for Python 2 and Python 3 respectively.
The bad Trex codes is in convert_val:
https://github.com/cisco-system-traffic-generator/trex-core/blob/master/scripts/automation/trex_control_plane/stl/trex_stl_lib/trex_stl_packet_builder_scapy.py#L674
def convert_val (val):
if is_integer(val):
return val
if type(val) == str:
return ipv4_str_to_num (is_valid_ipv4(val))
raise CTRexPacketBuildException(-11,("init val invalid %s ") % val );
This code is doing type(val) == str. This is bad and broken.
We can't fix Trex, so we have to render a |