A refactor-friendly configuration lib would help scala programmers to maintain config files without any pain, by using scala macro annotation.
Create a config-style trait as configuration definition, eg:
import com.wacai.config.annotation._
import scala.concurrent.duration._
@conf trait kafka {
val server = new {
val host = "wacai.com"
val port = 12306
}
val socket = new {
val timeout = 3 seconds
val buffer = 1024 * 64L
}
val client = "wacai"
}Use config by extending it,
class Consumer extends kafka {
val client = new SimpleConsumer(
server.host,
server.port,
socket.timeout,
socket.buffer,
client
)
...
}Compile, @conf will let scala compiler to insert codes to kafka.scala:
trait kafka {
val server = new {
val host = config.getString("kafka.server.host")
val port = config.getInt("kafka.server.port")
}
val socket = new {
val timeout = Duration(config.getDuration("kafka.socket.timeout", SECONDS))
val buffer = config.getBytes("kafka.socket.buffer")
}
val client = config.getString("kafka.client")
...
}After that, a config file named kafka.conf was generated at src/main/resources as blow:
kafka {
server {
host = wacai.com
port = 12306
}
socket {
timeout = 3s
buffer = 64K
}
client = wacai
}
Last but not least, a application.conf need to be created to include kafka.conf like:
include "kafka.conf"
Caution: only support scala 2.11.0+
Set up your project/build.properties to:
sbt.version = 0.13.5
sbt 0.13.6+ has NPE problem while compiling
Set up your build.sbt with:
addCompilerPlugin("org.scalamacros" % "paradise" % "2.0.1" cross CrossVersion.full)
libraryDependencies += "com.wacai" %% "config-annotation" % "0.3.4"| Scala type | Config getter | Value |
|---|---|---|
| Boolean | getBoolean | true/false |
| Int | getInt | number |
| Double | getDouble | float |
| String | getString | text |
| Long | getBytes | number with unit (B, K, M, G) |
| +Duration | getDuration | number with unit (ns, us, ms, s, m, h, d) |
import com.wacai.config.annotation._
@conf trait kafka extends Configurable { self: Actor =>
def config = context.system.settings.config
...
}Config files would be generated at src/main/resources as default.
It can be changed by appending macro setting to scalacOption in build.sbt:
scalacOptions += "-Xmacro-settings:conf.output.dir=/path/to/out"Please see config-annotation-example.
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