allow mut

[jvenant]

Maybe it could be a good idea to add

#[allow(unused_mut)]

at the begining of the file To prevent some warnings on collections ?

[lerouxrgd]

Do you happen to have an example where this would help ?

[jvenant]

Yes sure : I have an avro containing a field like :

    {
      "name": "labels",
      "type": {
        "type": "map",
        "values": "string"
      },
      "default": {}
    }

which is generated as :

            labels: { let mut m = ::std::collections::HashMap::new();  m },

and produce this warning at complile :

   |
51 |             labels: { let mut m = ::std::collections::HashMap::new();  m },
   |                           ----^
   |                           |
   |                           help: remove this `mut`
   |

because I don't edit the hasmap. I just replace it with code similar to :

labels: job.labels.into()

Saying that, I realized that removing the default from the avro changed the generated code to

labels: ::std::collections::HashMap::new()

and of course, this one don't generate any warning.

But that's not exactly what I want. I need a default to an empty map I totally understand why the no default version is immutable and the default version mutable. But for me this mutable behavior is semantically closer to the concept of an init value than a default value. In my mind :

• init is mutable an can be edited later
• default is immutable can be replaced by a non default value.

And also maybe, a map with no default should be an Option initialized to None ?

To summarize, I thing that having :

• default:{} converted to a mutable HashMap with unused_mut allowed
• no default converted to a None Option

Would be a good compromise and better fit my understanding of what default means

But it's an open discussion. Your library works very well already ! Thank you very much for your work and your contribution !

[lerouxrgd]

Thank you for the example, it is fixed in 0.9.2.

no default converted to a None Option

Actually None is only for union type where first value is null, this is the standard in Avro. So no default is converted to an empty HashMap.

[jvenant]

You're absolutely right for None. Thank you very much !

[lerouxrgd]

Closing this as the issue should be solved.