Scala - Revision history

Hoppinglife: /* RAII and Resource Handling */

2020-06-14T19:31:22Z

RAII and Resource Handling

← Older revision		Revision as of 19:31, 14 June 2020
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	<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.		<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 [~~http~~://~~jsuereth~~.com/scala-arm~~/index.html~~ scala-arm].		For Scala, the best resource-management mechanism seems to be a library [https://github.com/jsuereth/scala-arm scala-arm].

Hoppinglife: /* RAII and Resource Handling */

2020-06-14T16:42:14Z

RAII and Resource Handling

← Older revision		Revision as of 16:42, 14 June 2020
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	=== RAII and Resource Handling ===		=== 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 [http://jsuereth.com/scala-arm/index.html scala-arm].

Hoppinglife at 16:19, 14 June 2020

2020-06-14T16:19:31Z

← Older revision		Revision as of 16:19, 14 June 2020
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	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 ===

Hoppinglife at 02:00, 27 May 2020

2020-05-27T02:00:42Z

← Older revision		Revision as of 02:00, 27 May 2020
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	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.

Hoppinglife: /* Self Type */

2020-05-26T23:27:48Z

Self Type

← Older revision		Revision as of 23:27, 26 May 2020
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	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.
	<~~pre class~~="~~hljs~~ scala">
			<syntaxhighlight lang="scala">
	trait User {		trait User {
	def username: String		def username: String
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	def tweet(tweetText: String) = println(s"$username: $tweetText")		def tweet(tweetText: String) = println(s"$username: $tweetText")
	}		}
	</~~pre~~>		</syntaxhighlight>

	A question is how it is different from trait subclasses.		A question is how it is different from trait subclasses.

	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.

Hoppinglife: /* Type bounds */

2020-05-26T22:58:07Z

Type bounds

← Older revision		Revision as of 22:58, 26 May 2020
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	The official tour has a pretty good explanation: [https://docs.scala-lang.org/tour/upper-type-bounds.html Upper bounds] and [https://docs.scala-lang.org/tour/lower-type-bounds.html Lower bounds]		The official tour has a pretty good explanation: [https://docs.scala-lang.org/tour/upper-type-bounds.html Upper bounds] and [https://docs.scala-lang.org/tour/lower-type-bounds.html Lower bounds]

			=== Self Type ===

			A trait with a self type cannot be used without mixed in that trait first.
			<pre class="hljs scala">
			trait User {
			def username: String
			}

			trait Tweeter {
			this: User => // reassign this
			def tweet(tweetText: String) = println(s"$username: $tweetText")
			}
			</pre>

			A question is how it is different from trait subclasses.

			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.

Hoppinglife: Created page with "=== Type bounds === `B <: U` imposes a ''upper bound'' on type `U`, while `B >: L` imposes a ''lower bound''. This is useful for generic meth..."

2020-05-26T22:33:39Z

Created page with "=== Type bounds === <code>B <: U</code> imposes a ''upper bound'' on type <code>U</code>, while <code>B >: L</code> imposes a ''lower bound''. This is useful for generic meth..."

New page

=== Type bounds ===

<code>B <: U</code> imposes a ''upper bound'' on type <code>U</code>, while <code>B >: L</code> imposes a ''lower bound''. This is useful for generic methods that takes only classes on a particular inheritance tree as its type parameters.

The official tour has a pretty good explanation: [https://docs.scala-lang.org/tour/upper-type-bounds.html Upper bounds] and [https://docs.scala-lang.org/tour/lower-type-bounds.html Lower bounds]

Scala - Revision history

Hoppinglife: /* RAII and Resource Handling */

Hoppinglife: /* RAII and Resource Handling */

Hoppinglife at 16:19, 14 June 2020

Hoppinglife at 02:00, 27 May 2020

Hoppinglife: /* Self Type */

Hoppinglife: /* Type bounds */

Hoppinglife: Created page with "=== Type bounds === B <: U imposes a ''upper bound'' on type U, while B >: L imposes a ''lower bound''. This is useful for generic meth..."

Hoppinglife: Created page with "=== Type bounds === `B <: U` imposes a ''upper bound'' on type `U`, while `B >: L` imposes a ''lower bound''. This is useful for generic meth..."