On 27/03/19 5:56 PM, Oleg Ovcharuk wrote:
I’ve checked this solution. It doesn’t work as well in Python 2.7 - dumped yaml includes this ugly parts "!!python/object/apply:collections.OrderedDict».
It looks like you accidentally used yaml.dump() instead of yaml.safe_dump(), after adding the representer to only the SafeDumper class.
Yes, it could be fixed by including another hundred lines of code, but it still smells like we just copy and paste existing solution.
I've implemented this myself a couple of times and it is exactly 5 lines of code: https://github.com/openstack/tripleo-heat-templates/blob/master/network/endp... https://github.com/openstack/heat/blob/master/heat/common/template_format.py... Loading is more complicated though because you have to reimplement construct_mapping for maximum efficiency. The simplest version I can come up with is 9 lines: class OrderedLoader(yaml.SafeLoader): def construct_yaml_map_ordered(self, node): data = collections.OrderedDict() yield data value = self.construct_mapping(node) keys = (self.construct_object(kn) for kn, vn in node.value) data.update((k, value[k]) for k in keys) OrderedLoader.add_constructor(u'tag:yaml.org,2002:map', OrderedLoader.construct_yaml_map_ordered) but it obviously has the disadvantage of having to call construct_object() twice on each key. cheers, Zane.
15 февр. 2019 г., в 8:28, Renat Akhmerov <renat.akhmerov@gmail.com <mailto:renat.akhmerov@gmail.com>> написал(а):
This looks like a solution, yes. Thanks.
@Oleg, please take a look. Maybe we really decided to add a new yaml lib too early.
Renat On 15 Feb 2019, 00:16 +0700, Ben Nemec <openstack@nemebean.com <mailto:openstack@nemebean.com>>, wrote:
On 2/14/19 10:46 AM, Oleg Ovcharuk wrote:
Matthew, we use not only load, but also dump. We can't use custom constructor and default representer - the output will be terrible. This custom constructor contains about 50 lines of code, representer would have a similar count. Also, we should think about compatibility with Python 2.7, 3.x and about it's performance. Summary, we would have about 150 lines of code, which is just copy-paste from `yamlloader` library. IMHO, it is better to use existing solutions.
You don't need a complex representer to dump OrderedDicts. It can be done in about three lines: https://github.com/cybertron/tripleo-scripts/blob/105381d4f080394e68a40327c3...
That's the code I used when I wanted to dump dicts in a particular order. Once you add the representer OrderedDicts are handled as you would expect.
чт, 14 февр. 2019 г. в 19:14, Matthew Thode <mthode@mthode.org <mailto:mthode@mthode.org> <mailto:mthode@mthode.org>>:
On 19-02-14 16:58:49, Oleg Ovcharuk wrote:
Hi! Can you please add yamlloader library to global requirements? https://pypi.org/project/yamlloader/
It provides ability to preserve key order in dicts, it supports either python 2.7 and python 3.x, it provides better performance than built-in functions. Thank you.
I'd like to know a little more about why we need this, yaml as a spec itself doesn't guarantee order so order should be stored somewhere else.
If all you need is ordereddict support something like this may be better then adding yet another lib.
https://gist.github.com/enaeseth/844388
-- Matthew Thode