[Python-ideas] Suggestions: dict.flow_update and dict.__add__

Christopher Barker pythonchb at gmail.com
Tue Mar 5 11:11:06 EST 2019

On Tue, Mar 5, 2019 at 12:53 AM Jonathan Fine <jfine2358 at gmail.com> wrote:

> Instead of using dict + dict, perhaps use dict.flow_update. Here,
> flow_update is just like update, except that it returns self.

That violates an important convention in Python: mutating methods do not
return self. We really want to preserve that convention.

On the other hand, as seen in other recent threads, there is a desire for
chaining operations of many sorts, so a .flow_update() that returned a new
dict would provide that feature.

Though I would only recommend that if it was decided that we wanted to
generally support that approach for all mutable containers — which would
mean adding quite a few methods.

And we could then use the same naming convention for them all.

I’m not sure I like “flow_” though, it’s not very commonly known jargon.


Christopher Barker, PhD

Python Language Consulting
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