How to initialize embedded messages in Python?

[Jens Troeger]

Hello,

Following up on the documentation on Singular Message Fields (link) and its examples, I’m unclear on passing messages to the initializer. Building on the existing example:

message Foo { optional Bar bar = 1; } message Bar { optional int32 i = 1; }

I am not supposed to use

foo = Foo() foo.bar = Bar() # WRONG!

but what about

foo = Foo(bar=Bar(i=5))

In this case, will the generated initializer use e.g. CopyFrom() (docs) correctly? Or is the recommendation to use:

foo = Foo() bar = Bar()foo.bar.CopyFrom(bar)

The suggestion to write directly to fields of Bar can become tedious, particulalry if Bar is more complex and I’d like to compose messages form other messages.

Much thanks!

Jens

[Nathaniel Manista]

On Wed, Nov 8, 2023 at 7:42 AM Jens Troeger <jens.t...@gmail.com> wrote:

but what about

foo = Foo(bar=Bar(i=5))

This is the preferred form. Please consider adding your 👍 to issue 2782 about boosting the clarity of this preference in the documentation.

-N