->pool (clj)

Given a (connection pooled datasource) class and a database spec, return a connection pool object built from that class and the database spec. Assumes the `clazz` has a `.setJdbcUrl` method (which HikariCP and c3p0 do). If you already have a JDBC URL and want to use this method, pass `:jdbcUrl` in the database spec (instead of `:dbtype`, `:dbname`, etc). Properties for the connection pool object can be passed as mixed case keywords that correspond to setter methods (just as `:jdbcUrl` maps to `.setJdbcUrl`). `clojure.java.data/to-java` is used to construct the object and call the setters. If you need to pass in connection URL parameters, it can be easier to use `next.jdbc.connection/jdbc-url` to construct URL, e.g., (->pool HikariDataSource {:jdbcUrl (jdbc-url {:dbtype .. :dbname .. :useSSL false}) :username .. :password ..}) Here we pass `:useSSL false` to `jdbc-url` so that it ends up in the connection string, but pass `:username` and `:password` for the pool itself. Note that the result is not type-hinted (because there's no common base class or interface that can be assumed). In particular, connection pooled datasource objects may need to be closed but they don't necessarily implement `java.io.Closeable` (HikariCP does, c3p0 does not).