dnsco opened a new issue, #3644:
URL: https://github.com/apache/arrow-rs/issues/3644
I'm generating an arrow schema, and because there is not a macro, when it's
time set the values I need to invoke a macro like this:
```rust
macro_rules! set_value {
($builder:expr,$i:expr,$typ:ty,$getter:ident,$value:expr) => {{
let b: &mut $typ = $builder.field_builder::<$typ>($i).unwrap();
match $value {
Some(cow) => {
let v = cow.$getter().unwrap();
b.append_value(v)
}
None => b.append_null(),
}
}};
}
```
```rust
fn append_value(
f: &Field,
builder: &mut StructBuilder,
i: usize,
value: Option<Cow<Value>>,
) -> Result<()> {
match f.data_type() {
DataType::Float64 => set_value!(builder, i, Float64Builder, as_f64,
value),
DataType::Float32 => set_value!(builder, i, Float32Builder, as_f32,
value),
DataType::Int64 => set_value!(builder, i, Int64Builder, as_i64,
value),
DataType::Int32 => set_value!(builder, i, Int32Builder, as_i32,
value),
DataType::UInt64 => set_value!(builder, i, UInt64Builder, as_u64,
value),
DataType::UInt32 => set_value!(builder, i, UInt32Builder, as_u32,
value),
DataType::Utf8 => set_value!(builder, i, StringBuilder, as_str,
value),
DataType::LargeUtf8 => set_value!(builder, i, LargeStringBuilder,
as_str, value),
DataType::Binary => set_value!(builder, i, BinaryBuilder, as_bytes,
value),
DataType::LargeBinary => set_value!(builder, i, LargeBinaryBuilder,
as_bytes, value),
DataType::Boolean => set_value!(builder, i, BooleanBuilder, as_bool,
value),
...
}
```
If there was a trait that contained append_value and append_null this macro
could be replaced with a generic function, which would be a much better
developer experience.
Thanks for the library!
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