Trait ColumnSource 

#[doc(hidden)]
pub trait ColumnSource {
    // Required method
    fn into_column_list(self) -> List;

    // Provided methods
    unsafe fn into_named_columns(
        self,
        scope: &ProtectScope,
    ) -> Vec<(String, SEXP)>
       where Self: Sized { ... }
    fn into_dataframe(self) -> Result<DataFrame, DataFrameError>
       where Self: Sized { ... }
}

Internal engine that turns a value into a data.frame-shaped List.

This was the historical public convert::IntoDataFrame (-> List). It is now an internal engine: the public IntoDataFrame (-> Result<BuiltDataFrame, _>) and the enum-flatten codegen both delegate to it. Not part of the public verb surface.

Required Methods

fn into_column_list(self) -> List

Convert into a data.frame-shaped List (named columns, data.frame class, row.names).

Provided Methods

unsafe fn into_named_columns(self, scope: &ProtectScope) -> Vec<(String, SEXP)>

where Self: Sized,

Extract named column SEXPs from this value.

Returns (name, raw SEXP) per column. The assembled column list is protected in scope before anything is read from it, so every returned SEXP stays reachable (as an element of that list) for as long as scope lives, across any number of later allocations (#1748).

Safety

Must run on the R main thread, and scope must be the innermost live ProtectScope: its Drop unprotects from the top of R’s protect stack.

fn into_dataframe(self) -> Result<DataFrame, DataFrameError>

where Self: Sized,

Assemble this source into a validated DataFrame.

The column engine always sets the data.frame class (even for an empty frame); the one exception is the unnamed-row degradation, which returns a bare unclassed empty list — the old panic!("unnamed list elements") case, now a clean Err(UnnamedColumns).

This is the bridge from the internal column-assembly engine to the public DataFrame. We deliberately do not offer a blanket impl<T: ColumnSource> IntoDataFrame for T: #[derive(DataFrameRow)] emits a concrete impl IntoDataFrame for Vec<Row> per row type (and serde uses the SerdeRows<T> newtype), so a generic for T blanket would coherence-conflict with every one of those (the compiler treats Vec<Row>: ColumnSource as possibly-true). The derive’s into_dataframe glue calls this method instead.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors