Almost all Python classes implement __repr__ incorrectly, preventing normal use of help or printing of nested structures.

[exalate-issue-sync]

Python {{repr}} function should not print anything to the console, it should just return an internal representation of the instance, that can ideally be processed.
[https://docs.python.org/3/reference/datamodel.html#object.repr|https://docs.python.org/3/reference/datamodel.html#object.repr]

In the same way, {{str}} should not call {{print}} either, just return the string that's is going to be printed when user calls {{print}} on the object!
[https://docs.python.org/3/reference/datamodel.html#object.str|https://docs.python.org/3/reference/datamodel.html#object.str]

Many objects in h2o, also implement {{show}}: this methods is used to print complex objects.
Although, it seems to serve the same goal as {{print(obj)}}.
We can keep it for backwards compatibility but the printable string of an instance should be the result of {{str}} implementation, so that:

{code:python}def show(self):
print(self){code}

Among the side effects of this:

• in IPython/Jupyter instance details are printed when inspecting method using {{inst.method?}}, {{inst.method??}}.
• for debugging, for example when printing request results, we don't have the choice between printing {{repr()}} or {{str()}} (default), so that it prints some of its nested values BEFORE its keys... making this unreadable, non-parsable...

As a default implementation for {{repr}} in H2O classes, I would suggest something like:

{noformat}def repr(self):
r = dict(class='.'.join([self.class.module, self.class.name])
r.update(self.dict)
return repr(r){noformat}

[h2o-ops]

JIRA Issue Migration Info

Jira Issue: PUBDEV-7098
Assignee: Sebastien Poirier
Reporter: Sebastien Poirier
State: Resolved
Fix Version: 3.38.0.1
Attachments: N/A
Development PRs: Available

Linked PRs from JIRA

#6199
https://github.com/h2oai/h2oai-serving/pull/1079