Without this patch, it imports everything available in the scope.
```scala
scala> val a = 10l
val a = 10l
a: Long = 10
scala> import a._
import a._
import a._
scala> case class A(a: Int) // show
case class A(a: Int) // show
class $read extends Serializable {
def <init>() = {
super.<init>;
()
};
class $iwC extends Serializable {
def <init>() = {
super.<init>;
()
};
class $iwC extends Serializable {
def <init>() = {
super.<init>;
()
};
import org.apache.spark.SparkContext._;
class $iwC extends Serializable {
def <init>() = {
super.<init>;
()
};
val $VAL5 = $line5.$read.INSTANCE;
import $VAL5.$iw.$iw.$iw.$iw.a;
class $iwC extends Serializable {
def <init>() = {
super.<init>;
()
};
import a._;
class $iwC extends Serializable {
def <init>() = {
super.<init>;
()
};
class $iwC extends Serializable {
def <init>() = {
super.<init>;
()
};
case class A extends scala.Product with scala.Serializable {
<caseaccessor> <paramaccessor> val a: Int = _;
def <init>(a: Int) = {
super.<init>;
()
}
}
};
val $iw = new $iwC.<init>
};
val $iw = new $iwC.<init>
};
val $iw = new $iwC.<init>
};
val $iw = new $iwC.<init>
};
val $iw = new $iwC.<init>
};
val $iw = new $iwC.<init>
}
object $read extends scala.AnyRef {
def <init>() = {
super.<init>;
()
};
val INSTANCE = new $read.<init>
}
defined class A
```
With this patch, it just imports only the necessary.
```scala
scala> val a = 10l
val a = 10l
a: Long = 10
scala> import a._
import a._
import a._
scala> case class A(a: Int) // show
case class A(a: Int) // show
class $read extends Serializable {
def <init>() = {
super.<init>;
()
};
class $iwC extends Serializable {
def <init>() = {
super.<init>;
()
};
class $iwC extends Serializable {
def <init>() = {
super.<init>;
()
};
case class A extends scala.Product with scala.Serializable {
<caseaccessor> <paramaccessor> val a: Int = _;
def <init>(a: Int) = {
super.<init>;
()
}
}
};
val $iw = new $iwC.<init>
};
val $iw = new $iwC.<init>
}
object $read extends scala.AnyRef {
def <init>() = {
super.<init>;
()
};
val INSTANCE = new $read.<init>
}
defined class A
scala>
```
This patch also adds a `:fallback` mode on being enabled it will restore the spark-shell's 1.0.0 behaviour.
Author: Prashant Sharma <scrapcodes@gmail.com>
Author: Yin Huai <huai@cse.ohio-state.edu>
Author: Prashant Sharma <prashant.s@imaginea.com>
Closes#1635 from ScrapCodes/repl-fix-necessary-imports and squashes the following commits:
b1968d2 [Prashant Sharma] Added toschemaRDD to test case.
0b712bb [Yin Huai] Add a REPL test to test importing a method.
02ad8ff [Yin Huai] Add a REPL test for importing SQLContext.createSchemaRDD.
ed6d0c7 [Prashant Sharma] Added a fallback mode, incase users run into issues while using repl.
b63d3b2 [Prashant Sharma] SPARK-2632, SPARK-2576. Fixed by only importing what is necessary during class definition.
1499101113