ChameleonBuilder - Revision history

JaroslavTulach: /* Drawbacks */

JaroslavTulach — Mon, 20 Jun 2016 07:13:36 GMT

Drawbacks

←Older revision		Revision as of 07:13, 20 June 2016
Line 99:		Line 99:
	Result of build() method cannot be assigned to src. Expecting {{truffle\|com/oracle/truffle/api/source\|Source}} got {{JDK\|java/lang\|Void}}		Result of build() method cannot be assigned to src. Expecting {{truffle\|com/oracle/truffle/api/source\|Source}} got {{JDK\|java/lang\|Void}}
	This is a perfect indication that something is wrong. However the fix (e.g. one has to call '''mimetype''' method first) isn't completely obvious from the error message. [[Good]] [[Javadoc]] on the [[builder]] [[factory]] method or the '''build()''' method itself can fix that - however this is not as [[clueless]] solution is we might want.		This is a perfect indication that something is wrong. However the fix (e.g. one has to call '''mimetype''' method first) isn't completely obvious from the error message. [[Good]] [[Javadoc]] on the [[builder]] [[factory]] method or the '''build()''' method itself can fix that - however this is not as [[clueless]] solution is we might want.
		+
		+	Check [[ResistingBuilder]] to see a possible way to improve the [[ChameleonBuilder]] pattern.

JaroslavTulach: /* Drawbacks */

JaroslavTulach — Mon, 20 Jun 2016 07:12:09 GMT

Drawbacks

←Older revision		Revision as of 07:12, 20 June 2016
Line 87:		Line 87:


-	Sometimes it makes sense to mix the [[~~BuilderUnfinished~~]] pattern with [[BuilderWithConditionalException]]. Then you end up with a [[builder]] with two generic types. That doesn't support [[cluelessness]] either - in general [[clueless]] programmers are scared by generics. On the other hand, in the typical usage, the generics aren't visible:	+	Sometimes it makes sense to mix the [[ChameleonBuilder]] pattern with [[BuilderWithConditionalException]]. Then you end up with a [[builder]] with two generic types. That doesn't support [[cluelessness]] either - in general [[clueless]] programmers are scared by generics. On the other hand, in the typical usage, the generics aren't visible:

	<source lang="java">		<source lang="java">

JaroslavTulach: BuilderUnfinished moved to ChameleonBuilder: Chameleon is more sexy than unfinished encounter

JaroslavTulach — Thu, 16 Jun 2016 09:36:24 GMT

BuilderUnfinished moved to ChameleonBuilder: Chameleon is more sexy than unfinished encounter

←Older revision

Revision as of 09:36, 16 June 2016

JaroslavTulach: /* Drawbacks */

JaroslavTulach — Thu, 16 Jun 2016 09:25:00 GMT

Drawbacks

←Older revision		Revision as of 09:25, 16 June 2016
Line 98:		Line 98:
	The other problem is error reporting. The classical error is:		The other problem is error reporting. The classical error is:
	Result of build() method cannot be assigned to src. Expecting {{truffle\|com/oracle/truffle/api/source\|Source}} got {{JDK\|java/lang\|Void}}		Result of build() method cannot be assigned to src. Expecting {{truffle\|com/oracle/truffle/api/source\|Source}} got {{JDK\|java/lang\|Void}}
-	This is a perfect indication that something is wrong. However the fix (e.g. one has to call '''mimetype''' method) first isn't completely obvious from the error message. [[Good]] [[Javadoc]] on the [[builder]] [[factory]] method or the '''build()''' method itself can fix that - however this is not as [[clueless]] solution is we might want.	+	This is a perfect indication that something is wrong. However the fix (e.g. one has to call '''mimetype''' method first) isn't completely obvious from the error message. [[Good]] [[Javadoc]] on the [[builder]] [[factory]] method or the '''build()''' method itself can fix that - however this is not as [[clueless]] solution is we might want.

JaroslavTulach: /* Drawbacks */

JaroslavTulach — Thu, 16 Jun 2016 09:24:26 GMT

Drawbacks

←Older revision		Revision as of 09:24, 16 June 2016
Line 97:		Line 97:

	The other problem is error reporting. The classical error is:		The other problem is error reporting. The classical error is:
-	Result of build() method cannot be assigned to src. Expecting ({{truffle\|com/oracle/truffle/api/source\|Source}} got {{JDK\|java/lang\|Void}}	+	Result of build() method cannot be assigned to src. Expecting {{truffle\|com/oracle/truffle/api/source\|Source}} got {{JDK\|java/lang\|Void}}
	This is a perfect indication that something is wrong. However the fix (e.g. one has to call '''mimetype''' method) first isn't completely obvious from the error message. [[Good]] [[Javadoc]] on the [[builder]] [[factory]] method or the '''build()''' method itself can fix that - however this is not as [[clueless]] solution is we might want.		This is a perfect indication that something is wrong. However the fix (e.g. one has to call '''mimetype''' method) first isn't completely obvious from the error message. [[Good]] [[Javadoc]] on the [[builder]] [[factory]] method or the '''build()''' method itself can fix that - however this is not as [[clueless]] solution is we might want.

JaroslavTulach: /* Drawbacks */

JaroslavTulach — Thu, 16 Jun 2016 09:23:28 GMT

Drawbacks

←Older revision		Revision as of 09:23, 16 June 2016
Line 84:		Line 84:
	=== Drawbacks ===		=== Drawbacks ===

-	There can be only a single return type in [[Java]]. As such this [[APIDesignPatterns\|API pattern]] only works for a single ''essential'' [[builder]] property. One starts in the {{JDK\|java/lang\|Void}}-state and once it is set one changes the return type to the real one ({{truffle\|com/oracle/truffle/api/source\|Source}} in the previous case). This trick cannot be repeated more than once.	+	There can be only a single return type in [[Java]]. As such this [[APIDesignPatterns\|API pattern]] only works for a single ''essential'' [[builder]] property. One starts in the {{JDK\|java/lang\|Void}}-state and once any important attribute is set one changes the return type to the real one ({{truffle\|com/oracle/truffle/api/source\|Source}} in the previous case). This trick cannot be repeated more than once.

JaroslavTulach: /* Drawbacks */

JaroslavTulach — Thu, 16 Jun 2016 09:22:16 GMT

Drawbacks

←Older revision		Revision as of 09:22, 16 June 2016
Line 89:		Line 89:
	Sometimes it makes sense to mix the [[BuilderUnfinished]] pattern with [[BuilderWithConditionalException]]. Then you end up with a [[builder]] with two generic types. That doesn't support [[cluelessness]] either - in general [[clueless]] programmers are scared by generics. On the other hand, in the typical usage, the generics aren't visible:		Sometimes it makes sense to mix the [[BuilderUnfinished]] pattern with [[BuilderWithConditionalException]]. Then you end up with a [[builder]] with two generic types. That doesn't support [[cluelessness]] either - in general [[clueless]] programmers are scared by generics. On the other hand, in the typical usage, the generics aren't visible:

-	<source lang="~~lang~~">	+	<source lang="java">
	Source src = Builder.newFromText("function hello() { print 'Hello'; }").		Source src = Builder.newFromText("function hello() { print 'Hello'; }").
	name("hello.js").		name("hello.js").

JaroslavTulach: /* Initially Initialized */

JaroslavTulach — Thu, 16 Jun 2016 09:21:13 GMT

Initially Initialized

←Older revision		Revision as of 09:21, 16 June 2016
Line 73:		Line 73:

	<source lang="java">		<source lang="java">
		+	// define as
	public static Builder<Source> fromFile({{JDK\|java/io\|File}} file) { /* ... */ }		public static Builder<Source> fromFile({{JDK\|java/io\|File}} file) { /* ... */ }

JaroslavTulach: /* Initially Initialized */

JaroslavTulach — Thu, 16 Jun 2016 09:20:47 GMT

Initially Initialized

←Older revision		Revision as of 09:20, 16 June 2016
Line 73:		Line 73:

	<source lang="java">		<source lang="java">
-	public static Builder<Source> fromFile({{JDK\|java/io\|File}} file) { /* ... */ }	+	public static Builder<Source> fromFile({{JDK\|java/io\|File}} file) { /* ... */ }

-	// use it as	+	// use it as
-	Source src = Builder.fromFile(new File("c:\\x.js")).build();	+	Source src = Builder.fromFile(new File("c:\\x.js")).build();
	</source>		</source>

JaroslavTulach at 09:20, 16 June 2016

JaroslavTulach — Thu, 16 Jun 2016 09:20:16 GMT

←Older revision		Revision as of 09:20, 16 June 2016
Line 67:		Line 67:

	The type information is really compile time only information - e.g. it gets [[erasure\|erased]] during execution. Thus the performance of this [[APIDesignPatterns\|API Design Pattern]] is the same of plain builder - but rather on relying on runtime [[exception]]s saying something is missing - it co-operates with [[Javac]] to give the users early edit time/compile time error indications.		The type information is really compile time only information - e.g. it gets [[erasure\|erased]] during execution. Thus the performance of this [[APIDesignPatterns\|API Design Pattern]] is the same of plain builder - but rather on relying on runtime [[exception]]s saying something is missing - it co-operates with [[Javac]] to give the users early edit time/compile time error indications.
		+
		+	=== Initially Initialized ===
		+
		+	Of course, there can be other factory methods that can create the [[builder]] in a state that is already initialized. For example, if we create a {{truffle\|com/oracle/truffle/api/source\|Source}} from a real file on disk, we can ask the [[OS]] to guess the MIME type for us:
		+
		+	<source lang="java">
		+	public static Builder<Source> fromFile({{JDK\|java/io\|File}} file) { /* ... */ }
		+
		+	// use it as
		+	Source src = Builder.fromFile(new File("c:\\x.js")).build();
		+	</source>
		+
		+	There can be a mixture of such ''finished'' or ''unfinished'' [[builder]] factory methods in the same class.

	=== Drawbacks ===		=== Drawbacks ===

	There can be only a single return type in [[Java]]. As such this [[APIDesignPatterns\|API pattern]] only works for a single ''essential'' [[builder]] property. One starts in the {{JDK\|java/lang\|Void}}-state and once it is set one changes the return type to the real one ({{truffle\|com/oracle/truffle/api/source\|Source}} in the previous case). This trick cannot be repeated more than once.		There can be only a single return type in [[Java]]. As such this [[APIDesignPatterns\|API pattern]] only works for a single ''essential'' [[builder]] property. One starts in the {{JDK\|java/lang\|Void}}-state and once it is set one changes the return type to the real one ({{truffle\|com/oracle/truffle/api/source\|Source}} in the previous case). This trick cannot be repeated more than once.
		+
		+
		+	Sometimes it makes sense to mix the [[BuilderUnfinished]] pattern with [[BuilderWithConditionalException]]. Then you end up with a [[builder]] with two generic types. That doesn't support [[cluelessness]] either - in general [[clueless]] programmers are scared by generics. On the other hand, in the typical usage, the generics aren't visible:
		+
		+	<source lang="lang">
		+	Source src = Builder.newFromText("function hello() { print 'Hello'; }").
		+	name("hello.js").
		+	mimeType("text/javascript").
		+	build();
		+	</source>

	The other problem is error reporting. The classical error is:		The other problem is error reporting. The classical error is:
	Result of build() method cannot be assigned to src. Expecting ({{truffle\|com/oracle/truffle/api/source\|Source}} got {{JDK\|java/lang\|Void}}		Result of build() method cannot be assigned to src. Expecting ({{truffle\|com/oracle/truffle/api/source\|Source}} got {{JDK\|java/lang\|Void}}
	This is a perfect indication that something is wrong. However the fix (e.g. one has to call '''mimetype''' method) first isn't completely obvious from the error message. [[Good]] [[Javadoc]] on the [[builder]] [[factory]] method or the '''build()''' method itself can fix that - however this is not as [[clueless]] solution is we might want.		This is a perfect indication that something is wrong. However the fix (e.g. one has to call '''mimetype''' method) first isn't completely obvious from the error message. [[Good]] [[Javadoc]] on the [[builder]] [[factory]] method or the '''build()''' method itself can fix that - however this is not as [[clueless]] solution is we might want.
-
-