make r2d2 as a feature

Author: jaredzhou

Cargo.toml

@@ -28,6 +28,7 @@ modern-full = [
     "chrono",
     "serde_json",
     "url",
+    "r2d2",
 ]
 
 [dependencies]
@@ -48,7 +49,7 @@ cast = { version = "0.3", features = ["std"] }
 arrow = { version = "6.5.0", default-features = false, features = ["prettyprint"] }
 rust_decimal = "1.14"
 strum = { version = "0.23", features = ["derive"] }
-r2d2 = "0.8.9"
+r2d2 = { version = "0.8.9", optional = true }
 
 [dev-dependencies]
 doc-comment = "0.3"

src/lib.rs

@@ -78,6 +78,7 @@ pub use crate::config::{AccessMode, Config, DefaultNullOrder, DefaultOrder};
 pub use crate::error::Error;
 pub use crate::ffi::ErrorCode;
 pub use crate::params::{params_from_iter, Params, ParamsFromIter};
+#[cfg(feature = "r2d2")]
 pub use crate::r2d2::DuckdbConnectionManager;
 pub use crate::row::{AndThenRows, Map, MappedRows, Row, RowIndex, Rows};
 pub use crate::statement::Statement;
@@ -94,6 +95,7 @@ mod config;
 mod inner_connection;
 mod params;
 mod pragma;
+#[cfg(feature = "r2d2")]
 mod r2d2;
 mod raw_statement;
 mod row;