Scala: Difference between revisions
Jump to navigation
Jump to search
Hoppinglife (talk | contribs) |
Hoppinglife (talk | contribs) |
||
| (4 intermediate revisions by the same user not shown) | |||
| Line 8: | Line 8: | ||
A trait with a self type cannot be used without mixed in that trait first. | A trait with a self type cannot be used without mixed in that trait first. | ||
< | |||
<syntaxhighlight lang="scala"> | |||
trait User { | trait User { | ||
def username: String | def username: String | ||
| Line 17: | Line 18: | ||
def tweet(tweetText: String) = println(s"$username: $tweetText") | def tweet(tweetText: String) = println(s"$username: $tweetText") | ||
} | } | ||
</ | </syntaxhighlight> | ||
A question is how it is different from trait subclasses. | A question is how it is different from trait subclasses. | ||
=== Context Bound === | |||
See [https://docs.scala-lang.org/tour/self-types.html Official tour], [http://jonasboner.com/real-world-scala-dependency-injection-di/ a discussion on the cake pattern] and [https://stackoverflow.com/questions/1990948/what-is-the-difference-between-self-types-and-trait-subclasses a StackOverflow question] about this. | See [https://docs.scala-lang.org/tour/self-types.html Official tour], [http://jonasboner.com/real-world-scala-dependency-injection-di/ a discussion on the cake pattern] and [https://stackoverflow.com/questions/1990948/what-is-the-difference-between-self-types-and-trait-subclasses a StackOverflow question] about this. | ||
=== RAII and Resource Handling === | |||
Java and Scala do not have deterministic destructors due to automatic garbage collection. Java has a | |||
<code>finalize()</code> method in <code>Object</code>, but introduced [https://stackoverflow.com/questions/56139760/why-is-the-finalize-method-deprecated-in-java-9 problems] and were deprecated. Java classes holding non-heap resources should provide a close method, as well as lean on [https://docs.oracle.com/javase/9/docs/api/java/lang/ref/Cleaner.html Cleaner] and [https://docs.oracle.com/javase/8/docs/api/java/lang/AutoCloseable.html Autoclosable] to implement safe resource release. | |||
For Scala, the best resource-management mechanism seems to be a library [https://github.com/jsuereth/scala-arm scala-arm]. | |||