Aw: Re: Remembering imports between script invocations

[Jochen Theodorou]

let us assume we add a setConfig method to GroovyScriptEngineImpl... how would you call it?

 

ScriptEngineManager factory = new ScriptEngineManager();
ScriptEngine engine = factory.getEngineByName("groovy");
GroovyScriptEngineImpl groovyEngine = (GroovyScriptEngineImpl) engine;
groovyEngine.setConfig(myConfig);

which means you will require Groovy specific code to do this. And in that case there is always the question why you are not using the Groovy classes directly then.

 

But frankly... how about instead writing a small wrapper for GroovyShell or GroovyScriptEngine, that does implement ScriptEngine and register a factory? If you do not need support for ScriptContext, then this would be easy.

 

And then there would be also the option to do it similar to #jsr223.groovy.engine.keep.globals and make a special attribute in the engine context for GroovyScriptEngineImpl to let it set the additional imports.

 

bye Jochen

 

Gesendet: Donnerstag, 01. November 2018 um 16:19 Uhr
Von: "Keith Suderman" <suder...@cs.vassar.edu>
An: dev@groovy.apache.org
Betreff: Re: Remembering imports between script invocations

Hi David,

 

I am not a Groovy committer and I am not that familiar with the Groovy code base so _I_ can't revise the JSR-223 implementation.  I did take a quick look at the code, and other than having "GroovyScriptEngine" in their names the two classes (GroovyScriptEngine and GroovyScriptEngineImpl) have nothing in common and parse/load Groovy code in completely different ways.  I suspect adding a feature like you want would be a non-trivial undertaking.  Maybe one of the active committers (Paul, Daniel, et al)  can comment.

 

However, I suspect that the GroovyScriptEngineImpl class is "crippled" by JSR-223 itself as it caters to the lowest common denominator

 

- Keith

 

On Oct 31, 2018, at 12:12 PM, David Ekholm <da...@jalbum.net> wrote:

 

Hi Keith,

 

I'm "resurrecting" this old thread in an attept to see if we can use Groovy as the next scritpting language in jAlbum. What I'd really want to achive is to supply a number of default star imports. This is expecially important as Groovy sadly doesn't remember imports between script invocations.

 

I looked at your code suggetion below and tried to fit it to JSR-223 (javax.script API) but it fails as the GroovyScriptEngineImpl class I get from that API doesn't extend the GroovyScriptEngine class. It's only the GroovyScriptEngine class that supplies the important setConfig method.

 

Could you revise the JSR-223 implementation so it isn't unnecessary crippled compared to the GroovyShell API, at very least add the setConfig method to the GroovyScriptEngineImpl class? If we're to use the GroovyShell API, then we need to introduce our own abstraction layer in order to continue supporting multiple scripting languages in jAlbum.

 

Regards

/David, jAlbum founder

 

On 10 Feb 2018, at 21:25, Keith Suderman <suder...@anc.org> wrote:

 

Import statements are really just shortcuts to tell the compiler how to resolve class names so there is nothing to "remember" between invocations, that is, nothing gets added to the Binding.

 

I am not familiar with the javax.script API, but I suspect that you will have to provide your own ScriptEngine implementation as you will need to modify the CompilerConfiguration object the GroovyShell is using to compile the Groovy code.  For example:

 

        CompilerConfiguration configuration = new CompilerConfiguration()

        GroovyShell compiler = new GroovyShell(configuration)

        println compiler.evaluate('json=\'{"foo":"bar"}\'')

        println compiler.evaluate("groovy.json.JsonOutput.prettyPrint(json)")

 

        /* Fails: MissingPropertyException */

        /* println compiler.evaluate("JsonOutput.prettyPrint(json)") */

 

        ImportCustomizer imports = new ImportCustomizer()

        imports.addStarImports("groovy.json")

        configuration.addCompilationCustomizers(imports)

// Works, the compiler can now resolve groovy.json.JsonOutput

        println compiler.evaluate("JsonOutput.prettyPrint(json)")

 

The difficult part will be "hooking" into the compiler to know when an import statement is used so you can update your CompilerConfiguration object.  I am sure the really clever programmers here could come up with some sort of AST transform that would do this.  However, depending on what you are allowed to do one option would be to tell your users that you have a "Groovy DSL" and then implement an "include" method that users would use to "import" Java packages.

 

        println eval('json=\'{"foo":"bar"}\'')

        println eval('include "groovy.json"')

        println eval('JsonOutput.prettyPrint(json)')

 

    Object eval(String code) {

        Script script = compiler.parse(code)

        ExpandoMetaClass metaClass = new ExpandoMetaClass(script.class, false)

        metaClass.include = { String name ->

            ImportCustomizer includes = new ImportCustomizer()

            includes.addStarImports(name)

            configuration.addCompilationCustomizers(includes)

            "Imported $name"

        }

        metaClass.initialize()

        script.metaClass = metaClass

        script.run()

    }

 

Hopefully that gives you some ideas.

 

Cheers,

Keith

 

On Feb 8, 2018, at 3:47 PM, David Ekholm <da...@jalbum.net> wrote:

 

How do I do that via the javax.script API?

 

Even if this is possible via the javax.script API, chances are that a user wishes to ad-hoc add another import, but as they are forgotten between script invocations, it makes it hard to use Groovy to interactively create, say a Swing or JavaFX UI one line at a time. With BeanShell, the user can add the needed imports, execute that "script" and then continue to refer to the imported classes in the following script invocations. Making Groovy remember imports would make it behave in as nice fashion as the new JShell tool in Java 9. JShell unfortunately cannot run embedded via the javax.script API :-(

 

Regards

/David

 

On 8 Feb 2018, at 21:34, eric.mil...@thomsonreuters.com wrote:

 

You can add all the imports you want to your compiler configuration and they will be consistently available for all scripts.

 

From: David Ekholm [mailto:da...@jalbum.net] 
Sent: Thursday, February 08, 2018 2:12 PM
To: dev@groovy.apache.org
Subject: Remembering imports between script invocations 

 

We're considering supporting Groovy as an additional scripting language to our web gallery software jAlbum (http://jalbum.net), but one aspect bugs me: It doesn't seem like import statements are remembered between script invocations. This makes it far harder to use Groovy to prototype UIs within jAlbum's scripting console than for instance BeanShell (using the javax.script API). We currently support the slow BeanShell scripting language and _javascript_. BeanShell behaves well in this regard, remembering earlier imported packages between script invocations. Can this be added to Groovy or is there some API flag we can set?

 

Regards

/David, jAlbum founder and client lead developer.

 

----------------------

Keith Suderman

Research Associate

Department of Computer Science

Vassar College, Poughkeepsie NY

suder...@cs.vassar.edu

 

 

----------------------

Keith Suderman

Research Associate

Department of Computer Science

Vassar College, Poughkeepsie NY

suder...@cs.vassar.edu