Scalastyle proposed rules (Imports)

This page contains proposed rules for Scalastyle, category Imports.

Imports

RedundantImport

Checks for redundant import statements. An import statement is considered redundant if:

• It is a duplicate of another import. This is, when a class is imported more than once.
• The class imported is from the scala package, e.g. importing scala.String.
• The class imported is from the same package.

UnusedImports

Checks for unused import statements. Scalastyle uses a simple but very reliable algorithm to report on unused import statements. An import statement is considered unused if:

• It is not referenced in the file. The algorithm does not support wild-card imports like import scala.collection.mutable._;. Most IDE's provide very sophisticated checks for imports that handle wild-card imports.
• It is a duplicate of another import. This is when a class is imported more than once.
• The class imported is from the scala package. For example importing scala.String.
• The class imported is from the same package.
• [MJF Check this is the case for Scala] Optionally: it is referenced in Scaladoc comments. This check is off by default, as it is considered bad practice to introduce a compile time dependency for documentation purposes only. As an example, the import java.util.Date would be considered referenced with the Javadoc comment {@link Date}. The alternative to avoid introducing a compile time dependency would be to write the Javadoc comment as {@link java.util.Date}.

ImportOrder

Checks the ordering/grouping of imports. Features are:

• groups imports: ensures that groups of imports come in a specific order (e.g., scala. comes first, then everything else)
• adds a separation between groups : ensures that a blank line sit between each group
• sorts imports inside each group: ensures that imports within each group are in lexicographic order
• sorts according to case: ensures that the comparison between imports is case sensitive
• groups static imports: ensures the relative order between regular imports and static imports (see import orders)

Syntax

Checks syntax of imports. Features are:

• full imports: ensures that imports declare the full package (some exceptions should be possible when it is common, e.g. allow import scalaz._; import Scalaz._)