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https://issues.apache.org/jira/browse/GROOVY-7896?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15403957#comment-15403957
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Ted Naleid commented on GROOVY-7896:
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[~paulk] The workaround is that in old versions of RxJava (like the 1.1.2
version that Ratpack 1.3.3 is on), there are no methods to allow resetting the
{{rx.Observable.hook}} field as it's a {{static final}} field. In the latest
version, 1.1.8, this plugin system has been refactored to [delegate
hooks|https://github.com/ReactiveX/RxJava/blob/v1.1.8/src/main/java/rx/Observable.java#L98]
to a new
[{{RxJavaHooks}}|https://github.com/ReactiveX/RxJava/blob/v1.1.8/src/main/java/rx/plugins/RxJavaHooks.java#L246]
class that allows the app to {{clear}}, {{reset}}, and {{lockdown}} the hooks.
> Grape `@Grab` annotation calls zero-arg methods when installing jar with
> extension module
> -----------------------------------------------------------------------------------------
>
> Key: GROOVY-7896
> URL: https://issues.apache.org/jira/browse/GROOVY-7896
> Project: Groovy
> Issue Type: Bug
> Components: Grape
> Affects Versions: 2.4.7
> Reporter: Ted Naleid
>
> When using {{@Grab}} annotation and loading a jar file that extends classes
> via extension modules, it appears that it is silently calling zero-arg
> methods on the extension class.
> I've created a test project that shows this issue:
> https://github.com/tednaleid/groovybug-ext
> Here's the detail. If I have a class that extends {{String}} and also has a
> zero-arg {{initialize()}} method that's meant to be called by the user:
> {code:title=com/naleid/groovybug/StringExtensions.java}
> package com.naleid.groovybug;
> public abstract class StringExtensions {
> private static String append = null;
> private StringExtensions() { }
> public static void initialize() {
> System.out.println("initialized");
> if (append != null) {
> throw new RuntimeException("Already initialized");
> }
> append = "foo";
> }
> public static String appendFoo(String self) {
> return self + append;
> }
> }
> {code}
> and this in resources so it's registered:
> {code:title=META-INF/services/org.codehaus.groovy.runtime.ExtensionModule}
> moduleName=string-ext
> moduleVersion=
> extensionClasses=com.naleid.groovybug.StringExtensions
> {code}
> If I create a jar out of it, install it in my .m2 directory (linked gradle
> script does this with {{./gradlew install}} and then run this script:
> {code:title=demoBug.groovy}
> @Grab('groovybug:groovybug-ext:1.0')
> import com.naleid.groovybug.StringExtensions
> assert "bar ".appendFoo() == "bar null"
> StringExtensions.initialize()
> assert "bar ".appendFoo() == "bar foo"
> println "success!"
> {code}
> it fails with
> {code}
> Caught: Assertion failed:
> assert "bar ".appendFoo() == "bar null"
> | |
> bar foo false
> Assertion failed:
> assert "bar ".appendFoo() == "bar null"
> | |
> bar foo false
> at demoBug.run(demoBug.groovy:12)
> {code}
> If I remove the {{@Grab}} annotation and instead refer to the jar file via
> the classpath, it works fine:
> {code}
> groovy -classpath
> ~/.m2/repository/groovybug/groovybug-ext/1.0/groovybug-ext-1.0.jar
> demoWorking.groovy
> initialized
> success!
> {code}
> The linked project demos the issue. Where I hit it in "real life" was using
> {{@Grab}} on a Ratpack application that has a {{RxRatpack.initialize()}}
> method. This method was already called and it was confusing to have this
> ratpack script fail:
> {code:title=ratpackTest.groovy}
> @Grab('io.ratpack:ratpack-rx:1.3.3')
> import ratpack.rx.RxRatpack
> RxRatpack.initialize()
> {code}
> The {{initialize()}} blows up if it has already been called.
> {code}
> java.lang.IllegalStateException: Cannot install RxJava integration because
> another execution hook (class
> rx.plugins.RxJavaObservableExecutionHookDefault) is already installed
> at ratpack.rx.RxRatpack.initialize(RxRatpack.java:102)
> at ratpack.rx.RxRatpack$initialize.call(Unknown Source)
> at ConsoleScript0.run(ConsoleScript0:5)
> {code}
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