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Posted to users@groovy.apache.org by Dinko Srkoč <di...@gmail.com> on 2016/03/08 19:19:36 UTC
Re: Failing to change the value of a Java variable from wihtin a
Groovy script (potential issue?)
On 8 March 2016 at 18:11, Thierry Hanser
<Th...@lhasalimited.org> wrote:
>
> Thank you Jason, you were indeed right, without CompileStatic or using TypeChecked works.
Well, it works, but probably not the way you think it works. Here's
what you can do to get more insight into what's going on:
* print the script's variable bindings - add to `scriptSource`:
`println binding.variables`
* access the field `x` directly - to `JavaScriptDemo` add a method like this:
public String myX() { return x; }
then print that as well: `println myX()`
* run the script with and without `CompileStatic` and compare the results
After running the experiment you'll probably notice that the field `x`
is never really changed. When you try to add the value 'two' to `x`
you're actually creating a new binding variable. The difference with
CompileStatic is in accessing the field or the binding if binding
exists.
Cheers,
Dinko
>
> This is concerning as I would prefer static compilation (type checking being a must).
>
>
>
> I can work around the issue in my context but it impacts the elegance of the underlying DSL.
>
> However from the Groovy script engine perspective it is more concerning.
>
>
>
> Maybe Cedric or Guy know if there are any known issues and planned fixes related to that problem?
>
>
>
> Thanks again Jason.
>
>
>
> Thierry
>
>
>
> ---
>
> PS: There was a couple of typos in the source code (never post-edit in outlook ;-) ). Apologies for any inconveniences.
>
> Here is the correct adjusted and working code:
>
>
>
> import org.codehaus.groovy.control.CompilerConfiguration;
>
> import org.codehaus.groovy.control.customizers.ASTTransformationCustomizer;
>
>
>
> import groovy.lang.Binding;
>
> import groovy.lang.GroovyShell;
>
> import groovy.lang.Script;
>
> import groovy.transform.CompileStatic;;
>
>
>
> public abstract class JavaScriptDemo extends Script
>
> {
>
> public String x;
>
>
>
> public JavaScriptDemo()
>
> {
>
> x="one";
>
> System.out.println("init x: " + x);
>
> }
>
>
>
> /**
>
> * Demo main
>
> * @param args
>
> * @throws Throwable
>
> */
>
> public static void main(String...args) throws Throwable
>
> {
>
> ////
>
> // Compilation configuration
>
> CompilerConfiguration configuration = new CompilerConfiguration();
>
> configuration.addCompilationCustomizers(new ASTTransformationCustomizer(CompileStatic.class));
>
> configuration.setScriptBaseClass(JavaScriptDemo.class.getName());
>
> GroovyShell shell = new GroovyShell(JavaScriptDemo.class.getClassLoader(), new Binding(), configuration);
>
>
>
> // source code
>
> String scriptSource= "println '1 = ' + x; x = 'two'; println '2 = ' + x\n";
>
>
>
> // compile the source code and run the compiled script
>
> JavaScriptDemo compiledScript = (JavaScriptDemo)shell.parse(scriptSource);
>
> compiledScript.run();
>
> }
>
> }
>
>
>
> From: Winnebeck, Jason [mailto:Jason.Winnebeck@windstream.com]
> Sent: 08 March 2016 16:46
> To: users@groovy.apache.org
> Subject: RE: Failing to change the value of a Java variable from wihtin a Groovy script (potential issue?)
>
>
>
> Unfortunately static compile can be pretty flaky at times and I run into bugs often with it and have to redesign code. For small scripts I would advise against it (if you need type checking, use TypeChecked). I’m wondering if the script is getting compiled to get field x from the base class but favors setting binding.x = ‘two’ in the script.
>
>
>
> I would try without static compilation and see if it works. If it does work without static compilation, upgrade to the very latest Groovy (2.4.6) as bugs are fixed in static compiler all the time. If that doesn’t fix the problem, then change the Java field to private and create a getX() and setX(String). If that doesn’t work and you still need static compile, try an explicit setX(‘two’) or this.x = ‘two’ in the script. Historically the static compiler has been more reliable when you are more explicit.
>
>
>
> Jason
>
>
>
> From: Thierry Hanser [mailto:Thierry.Hanser@lhasalimited.org]
> Sent: Tuesday, March 08, 2016 11:32 AM
> To: 'users@groovy.apache.org' <us...@groovy.apache.org>
> Subject: Failing to change the value of a Java variable from wihtin a Groovy script (potential issue?)
>
>
>
> Hi,
>
>
>
> The following very simple code is behaving really strangely.
>
> Could anyone please tell me if this is an issue in Groovy or something I am not doing properly (I would like to vote for the latter, yet...).
>
>
>
> In Java
>
>
>
> x='one';
>
> System.out.println("init x: " + x);
>
>
>
> In Groovy
>
>
>
> println '1 = ' + x
>
> x = 'two'
>
> println '2 = ' + x
>
>
>
> Output:
>
>
>
> init x: one <- initial value assignement OK
>
>
>
> 1 = one <- successfully accessing ‘x’ from within the compiled script OK
>
> the Groovy script has picked up the value of the Java variable;
>
> the implicit getX() has been called
>
>
>
> 2 = one <- should be ‘two’ as per Groovy code (second line)
>
> but is unchanged ???
>
>
>
> It seems that the Groovy script can’t change the value of ‘x’ (can’t access setX()). However there is no compilation error (‘x’ is not read-only)
>
> When implementing getX/setX methods, only the getter is called (in both print statements, line 1,3) but during the assignment instruction (line 2), the setter is silently ignored (the value of ‘x’ remains ‘one’ instead of ‘two’.
>
>
>
> The Java/Groovy binding is operational since the ‘one’ value of ‘x’ in the Java base class is successfully retrieved. So could anyone please tell me where the issue is?
>
> The confusing part is that even within in the Groovy context alone, the assignment ‘x=’two’ is not honoured (and yet there are no compilation/runtime error)
>
>
>
> Note that I tried all combinations of setters/getters/visibility and can at the best read but never modify the variable ‘x’. The same behaviour occurs with using the GroovyScriptEngine or GroovyClassLoader
>
>
>
> Thank you very much in advance for your help.
>
>
>
> Thierry
>
> -
>
>
>
> PS: (I am not sure if my previous message went through as I was still in the mailing list registration process, apologies if it is a duplicate)
>
>
>
> Full code:
>
>
>
> import org.codehaus.groovy.control.CompilerConfiguration;
>
> import org.codehaus.groovy.control.customizers.ASTTransformationCustomizer;
>
>
>
> import groovy.lang.Binding;
>
> import groovy.lang.Closure
>
> import groovy.lang.GroovyClassLoader;
>
> import groovy.lang.GroovyShell;
>
> import groovy.transform.CompileStatic;;
>
>
>
> abstract class GroovyDemoScript extends Script
>
> {
>
> public String x;
>
>
>
> public GroovyDemoScript()
>
> {
>
> x='one';
>
> System.out.println("init x: " + x);
>
> }
>
>
>
> public static void main(String...args) throws Throwable
>
> {
>
> ////
>
> // Compilation configuration
>
> CompilerConfiguration configuration = new CompilerConfiguration();
>
> configuration.addCompilationCustomizers(new ASTTransformationCustomizer(CompileStatic.class));
>
>
>
> // make sure we use the Java base class where ‘x’ is defined
>
> configuration.setScriptBaseClass(GroovyDemoScript.class.name);
>
>
>
> GroovyShell shell = new GroovyShell(this.getClass().getClassLoader(), new Binding(), configuration);
>
>
>
> // source code
>
> String scriptSource= "println '1 = ' + x; x = 'two'; println '2 = ' + x\n";
>
>
>
> // compile the source code and run the compiled script
>
> GroovyDemoScript compiledScript = shell.parse(scriptSource);
>
> compiledScript.run();
>
> }
>
> }
>
>
>
> ________________________________
>
> Switchboard: +44 (0)113 394 6020
>
> Technical Support: +44 (0)113 394 6030
>
> ________________________________
>
> Lhasa Limited, a not-for-profit organisation, promotes scientific knowledge & understanding through the development of computer-aided reasoning & information systems in chemistry & the life sciences. Registered Charity Number 290866. Registered Office: Granary Wharf House, 2 Canal Wharf, Leeds, LS11 5PS. Company Registration Number 01765239. Registered in England and Wales.
>
> This communication, including any associated attachments, is intended for the use of the addressee only and may contain confidential, privileged or copyright material. If you are not the intended recipient, you must not copy this message or attachment or disclose the contents to any other person. If you have received this transmission in error, please notify the sender immediately and delete the message and any attachment from your system. Except where specifically stated, any views expressed in this message are those of the individual sender and do not represent the views of Lhasa Limited. Lhasa Limited cannot accept liability for any statements made which are the sender's own. Lhasa Limited does not guarantee that electronic communications, including any attachments, are free of viruses. Virus scanning is recommended and is the responsibility of the recipient.
>
> ________________________________
>
> This email message and any attachments are for the sole use of the intended recipient(s). Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message and any attachments.
RE: Failing to change the value of a Java variable from wihtin a
Groovy script (potential issue?)
Posted by Thierry Hanser <Th...@lhasalimited.org>.
Apologies, I meant the binding variables are empty at start (x is not explicitly bound) yet the value of x is retrieved (as part of the base script class) and you are right Dinko, the assignment statement subsequently binds explicitly the variable [x:two] and by doing so somehow disconnects it from the original base script class which is the issues observed.
Interestingly when wrapping the code in a closure the assignment works properly (still creates a binding and keeps the link to the base class 'x' variable). Then if I create explicit getter/setter we fall back to the wrong behaviour, even within a closure.
Adding in the base script class:
public Object process(Closure code)
{
System.out.println("Processing with x : " + x);
return code.call();
}
And in Groovy:
Process
{
println '1 = ' + x
x = x + 'two'
println '2 = ' + x
}
Output:
init x: one
Processing with x : one
1 = one
2 = two
As expected
adding in the base class:
public void setX(String value)
{
x = value;
System.out.println("Setting x to : " + value + " => x = " + x);
}
public String getX()
{
System.out.println("Getting x : " + x);
return x;
}
will produce again:
init x: one
Processing with x : one
Getting x : one
1 = one
Getting x : one
2 = one
Note that the getter is always properly called but the setter is never called.
Finally removing the setter (to test the compile time analysis) produces:
Script1.groovy: 1: [Static type checking] - Cannot set read-only property: x
@ line 1, column 29.
process{println '1 = ' + x; x = 'two'; println '2 = ' + x
which is expected and demonstrate the acknowledgment of the setter setX() when present;
The issue is related to CompileChecked and can be summarised in that the setter is acknowledged at compile time but not called at runtime.
(again using just TypeChecked instead of CompileStatic removes the problem which
tells us that the problem lies in CompileStatic as pointed by Jason)
Cheers
Thierry
-----Original Message-----
From: Dinko Srkoč [mailto:dinko.srkoc@gmail.com]
Sent: 09 March 2016 11:36
To: users@groovy.apache.org
Subject: Re: Failing to change the value of a Java variable from wihtin a Groovy script (potential issue?)
On 9 March 2016 at 11:56, Thierry Hanser <Th...@lhasalimited.org>> wrote:
> Thank you for the suggestion Dinko.
>
> I tried your experiment and the binding variables set remains actually
> empty ([:]) which is what I expected since there is no explicit
> binding involved (the variable 'x' is directly declared in the base
> script which is the point of the approach)
Interestingly this is different from what I'm getting. The statement `x = 'two'` adds the value 'two' to the newly added binding variable `x` (with binding being empty before that statement).
Cheers,
Dinko
>
> An interesting hint to the problem is that if I explicitly implement the getter and don't have a setter, there will be indeed an expected 'can't change a read-only value' compilation error which means that the getter/setter status is correctly analysed in the compilation decision tree and the setter must be present (or implicit) in order to allow the assignment in line 2 (x = 'two'); the problem is that it is not invoked at runtime; i.e. at compilation time Groovy's understanding is correct but the compiled code does not actually invoke the setter.
>
> This is disturbing and concerning as it leads to unpredictable behaviour.
>
> Thierry
>
>
> -----Original Message-----
> From: Dinko Srkoč [mailto:dinko.srkoc@gmail.com]
> Sent: 08 March 2016 18:20
> To: users@groovy.apache.org<ma...@groovy.apache.org>
> Subject: Re: Failing to change the value of a Java variable from
> wihtin a Groovy script (potential issue?)
>
> On 8 March 2016 at 18:11, Thierry Hanser <Th...@lhasalimited.org>> wrote:
>>
>> Thank you Jason, you were indeed right, without CompileStatic or using TypeChecked works.
>
> Well, it works, but probably not the way you think it works. Here's what you can do to get more insight into what's going on:
>
> * print the script's variable bindings - add to `scriptSource`:
> `println binding.variables`
> * access the field `x` directly - to `JavaScriptDemo` add a method like this:
>
> public String myX() { return x; }
>
> then print that as well: `println myX()`
> * run the script with and without `CompileStatic` and compare the
> results
>
> After running the experiment you'll probably notice that the field `x` is never really changed. When you try to add the value 'two' to `x` you're actually creating a new binding variable. The difference with CompileStatic is in accessing the field or the binding if binding exists.
>
> Cheers,
> Dinko
>
>>
>> This is concerning as I would prefer static compilation (type checking being a must).
>>
>>
>>
>> I can work around the issue in my context but it impacts the elegance of the underlying DSL.
>>
>> However from the Groovy script engine perspective it is more concerning.
>>
>>
>>
>> Maybe Cedric or Guy know if there are any known issues and planned fixes related to that problem?
>>
>>
>>
>> Thanks again Jason.
>>
>>
>>
>> Thierry
>>
>>
>>
>> ---
>>
>> PS: There was a couple of typos in the source code (never post-edit in outlook ;-) ). Apologies for any inconveniences.
>>
>> Here is the correct adjusted and working code:
>>
>>
>>
>> import org.codehaus.groovy.control.CompilerConfiguration;
>>
>> import
>> org.codehaus.groovy.control.customizers.ASTTransformationCustomizer;
>>
>>
>>
>> import groovy.lang.Binding;
>>
>> import groovy.lang.GroovyShell;
>>
>> import groovy.lang.Script;
>>
>> import groovy.transform.CompileStatic;;
>>
>>
>>
>> public abstract class JavaScriptDemo extends Script
>>
>> {
>>
>> public String x;
>>
>>
>>
>> public JavaScriptDemo()
>>
>> {
>>
>> x="one";
>>
>> System.out.println("init x: " + x);
>>
>> }
>>
>>
>>
>> /**
>>
>> * Demo main
>>
>> * @param args
>>
>> * @throws Throwable
>>
>> */
>>
>> public static void main(String...args) throws Throwable
>>
>> {
>>
>> ////
>>
>> // Compilation configuration
>>
>> CompilerConfiguration configuration = new
>> CompilerConfiguration();
>>
>> configuration.addCompilationCustomizers(new
>> ASTTransformationCustomizer(CompileStatic.class));
>>
>>
>> configuration.setScriptBaseClass(JavaScriptDemo.class.getName());
>>
>> GroovyShell shell = new
>> GroovyShell(JavaScriptDemo.class.getClassLoader(), new Binding(),
>> configuration);
>>
>>
>>
>> // source code
>>
>> String scriptSource= "println '1 = ' + x; x = 'two';
>> println '2 = ' + x\n";
>>
>>
>>
>> // compile the source code and run the compiled script
>>
>> JavaScriptDemo compiledScript =
>> (JavaScriptDemo)shell.parse(scriptSource);
>>
>> compiledScript.run();
>>
>> }
>>
>> }
>>
>>
>>
>> From: Winnebeck, Jason [mailto:Jason.Winnebeck@windstream.com]
>> Sent: 08 March 2016 16:46
>> To: users@groovy.apache.org<ma...@groovy.apache.org>
>> Subject: RE: Failing to change the value of a Java variable from
>> wihtin a Groovy script (potential issue?)
>>
>>
>>
>> Unfortunately static compile can be pretty flaky at times and I run into bugs often with it and have to redesign code. For small scripts I would advise against it (if you need type checking, use TypeChecked). I’m wondering if the script is getting compiled to get field x from the base class but favors setting binding.x = ‘two’ in the script.
>>
>>
>>
>> I would try without static compilation and see if it works. If it does work without static compilation, upgrade to the very latest Groovy (2.4.6) as bugs are fixed in static compiler all the time. If that doesn’t fix the problem, then change the Java field to private and create a getX() and setX(String). If that doesn’t work and you still need static compile, try an explicit setX(‘two’) or this.x = ‘two’ in the script. Historically the static compiler has been more reliable when you are more explicit.
>>
>>
>>
>> Jason
>>
>>
>>
>> From: Thierry Hanser [mailto:Thierry.Hanser@lhasalimited.org]
>> Sent: Tuesday, March 08, 2016 11:32 AM
>> To: 'users@groovy.apache.org' <us...@groovy.apache.org>>
>> Subject: Failing to change the value of a Java variable from wihtin a
>> Groovy script (potential issue?)
>>
>>
>>
>> Hi,
>>
>>
>>
>> The following very simple code is behaving really strangely.
>>
>> Could anyone please tell me if this is an issue in Groovy or something I am not doing properly (I would like to vote for the latter, yet...).
>>
>>
>>
>> In Java
>>
>>
>>
>> x='one';
>>
>> System.out.println("init x: " + x);
>>
>>
>>
>> In Groovy
>>
>>
>>
>> println '1 = ' + x
>>
>> x = 'two'
>>
>> println '2 = ' + x
>>
>>
>>
>> Output:
>>
>>
>>
>> init x: one <- initial value assignement OK
>>
>>
>>
>> 1 = one <- successfully accessing ‘x’ from within the compiled script OK
>>
>> the Groovy script has picked up the value of the Java
>> variable;
>>
>> the implicit getX() has been called
>>
>>
>>
>> 2 = one <- should be ‘two’ as per Groovy code (second line)
>>
>> but is unchanged ???
>>
>>
>>
>> It seems that the Groovy script can’t change the value of ‘x’ (can’t
>> access setX()). However there is no compilation error (‘x’ is not
>> read-only)
>>
>> When implementing getX/setX methods, only the getter is called (in both print statements, line 1,3) but during the assignment instruction (line 2), the setter is silently ignored (the value of ‘x’ remains ‘one’ instead of ‘two’.
>>
>>
>>
>> The Java/Groovy binding is operational since the ‘one’ value of ‘x’ in the Java base class is successfully retrieved. So could anyone please tell me where the issue is?
>>
>> The confusing part is that even within in the Groovy context alone,
>> the assignment ‘x=’two’ is not honoured (and yet there are no
>> compilation/runtime error)
>>
>>
>>
>> Note that I tried all combinations of setters/getters/visibility and
>> can at the best read but never modify the variable ‘x’. The same
>> behaviour occurs with using the GroovyScriptEngine or
>> GroovyClassLoader
>>
>>
>>
>> Thank you very much in advance for your help.
>>
>>
>>
>> Thierry
>>
>> -
>>
>>
>>
>> PS: (I am not sure if my previous message went through as I was still
>> in the mailing list registration process, apologies if it is a
>> duplicate)
>>
>>
>>
>> Full code:
>>
>>
>>
>> import org.codehaus.groovy.control.CompilerConfiguration;
>>
>> import
>> org.codehaus.groovy.control.customizers.ASTTransformationCustomizer;
>>
>>
>>
>> import groovy.lang.Binding;
>>
>> import groovy.lang.Closure
>>
>> import groovy.lang.GroovyClassLoader;
>>
>> import groovy.lang.GroovyShell;
>>
>> import groovy.transform.CompileStatic;;
>>
>>
>>
>> abstract class GroovyDemoScript extends Script
>>
>> {
>>
>> public String x;
>>
>>
>>
>> public GroovyDemoScript()
>>
>> {
>>
>> x='one';
>>
>> System.out.println("init x: " + x);
>>
>> }
>>
>>
>>
>> public static void main(String...args) throws Throwable
>>
>> {
>>
>> ////
>>
>> // Compilation configuration
>>
>> CompilerConfiguration configuration = new
>> CompilerConfiguration();
>>
>> configuration.addCompilationCustomizers(new
>> ASTTransformationCustomizer(CompileStatic.class));
>>
>>
>>
>> // make sure we use the Java base
>> class where ‘x’ is defined
>>
>>
>> configuration.setScriptBaseClass(GroovyDemoScript.class.name);
>>
>>
>>
>> GroovyShell shell = new
>> GroovyShell(this.getClass().getClassLoader(), new Binding(),
>> configuration);
>>
>>
>>
>> // source code
>>
>> String scriptSource= "println '1 = ' + x; x = 'two';
>> println '2 = ' + x\n";
>>
>>
>>
>> // compile the source code and run the compiled script
>>
>> GroovyDemoScript compiledScript =
>> shell.parse(scriptSource);
>>
>> compiledScript.run();
>>
>> }
>>
>> }
>>
>>
>>
>> ________________________________
>>
>> Switchboard: +44 (0)113 394 6020
>>
>> Technical Support: +44 (0)113 394 6030
>>
>> ________________________________
>>
>> Lhasa Limited, a not-for-profit organisation, promotes scientific knowledge & understanding through the development of computer-aided reasoning & information systems in chemistry & the life sciences. Registered Charity Number 290866. Registered Office: Granary Wharf House, 2 Canal Wharf, Leeds, LS11 5PS. Company Registration Number 01765239. Registered in England and Wales.
>>
>> This communication, including any associated attachments, is intended for the use of the addressee only and may contain confidential, privileged or copyright material. If you are not the intended recipient, you must not copy this message or attachment or disclose the contents to any other person. If you have received this transmission in error, please notify the sender immediately and delete the message and any attachment from your system. Except where specifically stated, any views expressed in this message are those of the individual sender and do not represent the views of Lhasa Limited. Lhasa Limited cannot accept liability for any statements made which are the sender's own. Lhasa Limited does not guarantee that electronic communications, including any attachments, are free of viruses. Virus scanning is recommended and is the responsibility of the recipient.
>>
>> ________________________________
>>
>> This email message and any attachments are for the sole use of the intended recipient(s). Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message and any attachments.
Re: Failing to change the value of a Java variable from wihtin a
Groovy script (potential issue?)
Posted by Dinko Srkoč <di...@gmail.com>.
On 9 March 2016 at 11:56, Thierry Hanser
<Th...@lhasalimited.org> wrote:
> Thank you for the suggestion Dinko.
>
> I tried your experiment and the binding variables set remains actually empty ([:]) which is what I expected since there is no explicit binding involved (the variable 'x' is directly declared in the base script which is the point of the approach)
Interestingly this is different from what I'm getting. The statement
`x = 'two'` adds the value 'two' to the newly added binding variable
`x` (with binding being empty before that statement).
Cheers,
Dinko
>
> An interesting hint to the problem is that if I explicitly implement the getter and don't have a setter, there will be indeed an expected 'can't change a read-only value' compilation error which means that the getter/setter status is correctly analysed in the compilation decision tree and the setter must be present (or implicit) in order to allow the assignment in line 2 (x = 'two'); the problem is that it is not invoked at runtime; i.e. at compilation time Groovy's understanding is correct but the compiled code does not actually invoke the setter.
>
> This is disturbing and concerning as it leads to unpredictable behaviour.
>
> Thierry
>
>
> -----Original Message-----
> From: Dinko Srkoč [mailto:dinko.srkoc@gmail.com]
> Sent: 08 March 2016 18:20
> To: users@groovy.apache.org
> Subject: Re: Failing to change the value of a Java variable from wihtin a Groovy script (potential issue?)
>
> On 8 March 2016 at 18:11, Thierry Hanser <Th...@lhasalimited.org> wrote:
>>
>> Thank you Jason, you were indeed right, without CompileStatic or using TypeChecked works.
>
> Well, it works, but probably not the way you think it works. Here's what you can do to get more insight into what's going on:
>
> * print the script's variable bindings - add to `scriptSource`:
> `println binding.variables`
> * access the field `x` directly - to `JavaScriptDemo` add a method like this:
>
> public String myX() { return x; }
>
> then print that as well: `println myX()`
> * run the script with and without `CompileStatic` and compare the results
>
> After running the experiment you'll probably notice that the field `x` is never really changed. When you try to add the value 'two' to `x` you're actually creating a new binding variable. The difference with CompileStatic is in accessing the field or the binding if binding exists.
>
> Cheers,
> Dinko
>
>>
>> This is concerning as I would prefer static compilation (type checking being a must).
>>
>>
>>
>> I can work around the issue in my context but it impacts the elegance of the underlying DSL.
>>
>> However from the Groovy script engine perspective it is more concerning.
>>
>>
>>
>> Maybe Cedric or Guy know if there are any known issues and planned fixes related to that problem?
>>
>>
>>
>> Thanks again Jason.
>>
>>
>>
>> Thierry
>>
>>
>>
>> ---
>>
>> PS: There was a couple of typos in the source code (never post-edit in outlook ;-) ). Apologies for any inconveniences.
>>
>> Here is the correct adjusted and working code:
>>
>>
>>
>> import org.codehaus.groovy.control.CompilerConfiguration;
>>
>> import
>> org.codehaus.groovy.control.customizers.ASTTransformationCustomizer;
>>
>>
>>
>> import groovy.lang.Binding;
>>
>> import groovy.lang.GroovyShell;
>>
>> import groovy.lang.Script;
>>
>> import groovy.transform.CompileStatic;;
>>
>>
>>
>> public abstract class JavaScriptDemo extends Script
>>
>> {
>>
>> public String x;
>>
>>
>>
>> public JavaScriptDemo()
>>
>> {
>>
>> x="one";
>>
>> System.out.println("init x: " + x);
>>
>> }
>>
>>
>>
>> /**
>>
>> * Demo main
>>
>> * @param args
>>
>> * @throws Throwable
>>
>> */
>>
>> public static void main(String...args) throws Throwable
>>
>> {
>>
>> ////
>>
>> // Compilation configuration
>>
>> CompilerConfiguration configuration = new
>> CompilerConfiguration();
>>
>> configuration.addCompilationCustomizers(new
>> ASTTransformationCustomizer(CompileStatic.class));
>>
>>
>> configuration.setScriptBaseClass(JavaScriptDemo.class.getName());
>>
>> GroovyShell shell = new
>> GroovyShell(JavaScriptDemo.class.getClassLoader(), new Binding(),
>> configuration);
>>
>>
>>
>> // source code
>>
>> String scriptSource= "println '1 = ' + x; x = 'two';
>> println '2 = ' + x\n";
>>
>>
>>
>> // compile the source code and run the compiled script
>>
>> JavaScriptDemo compiledScript =
>> (JavaScriptDemo)shell.parse(scriptSource);
>>
>> compiledScript.run();
>>
>> }
>>
>> }
>>
>>
>>
>> From: Winnebeck, Jason [mailto:Jason.Winnebeck@windstream.com]
>> Sent: 08 March 2016 16:46
>> To: users@groovy.apache.org
>> Subject: RE: Failing to change the value of a Java variable from
>> wihtin a Groovy script (potential issue?)
>>
>>
>>
>> Unfortunately static compile can be pretty flaky at times and I run into bugs often with it and have to redesign code. For small scripts I would advise against it (if you need type checking, use TypeChecked). I’m wondering if the script is getting compiled to get field x from the base class but favors setting binding.x = ‘two’ in the script.
>>
>>
>>
>> I would try without static compilation and see if it works. If it does work without static compilation, upgrade to the very latest Groovy (2.4.6) as bugs are fixed in static compiler all the time. If that doesn’t fix the problem, then change the Java field to private and create a getX() and setX(String). If that doesn’t work and you still need static compile, try an explicit setX(‘two’) or this.x = ‘two’ in the script. Historically the static compiler has been more reliable when you are more explicit.
>>
>>
>>
>> Jason
>>
>>
>>
>> From: Thierry Hanser [mailto:Thierry.Hanser@lhasalimited.org]
>> Sent: Tuesday, March 08, 2016 11:32 AM
>> To: 'users@groovy.apache.org' <us...@groovy.apache.org>
>> Subject: Failing to change the value of a Java variable from wihtin a
>> Groovy script (potential issue?)
>>
>>
>>
>> Hi,
>>
>>
>>
>> The following very simple code is behaving really strangely.
>>
>> Could anyone please tell me if this is an issue in Groovy or something I am not doing properly (I would like to vote for the latter, yet...).
>>
>>
>>
>> In Java
>>
>>
>>
>> x='one';
>>
>> System.out.println("init x: " + x);
>>
>>
>>
>> In Groovy
>>
>>
>>
>> println '1 = ' + x
>>
>> x = 'two'
>>
>> println '2 = ' + x
>>
>>
>>
>> Output:
>>
>>
>>
>> init x: one <- initial value assignement OK
>>
>>
>>
>> 1 = one <- successfully accessing ‘x’ from within the compiled script OK
>>
>> the Groovy script has picked up the value of the Java
>> variable;
>>
>> the implicit getX() has been called
>>
>>
>>
>> 2 = one <- should be ‘two’ as per Groovy code (second line)
>>
>> but is unchanged ???
>>
>>
>>
>> It seems that the Groovy script can’t change the value of ‘x’ (can’t
>> access setX()). However there is no compilation error (‘x’ is not
>> read-only)
>>
>> When implementing getX/setX methods, only the getter is called (in both print statements, line 1,3) but during the assignment instruction (line 2), the setter is silently ignored (the value of ‘x’ remains ‘one’ instead of ‘two’.
>>
>>
>>
>> The Java/Groovy binding is operational since the ‘one’ value of ‘x’ in the Java base class is successfully retrieved. So could anyone please tell me where the issue is?
>>
>> The confusing part is that even within in the Groovy context alone,
>> the assignment ‘x=’two’ is not honoured (and yet there are no
>> compilation/runtime error)
>>
>>
>>
>> Note that I tried all combinations of setters/getters/visibility and
>> can at the best read but never modify the variable ‘x’. The same
>> behaviour occurs with using the GroovyScriptEngine or
>> GroovyClassLoader
>>
>>
>>
>> Thank you very much in advance for your help.
>>
>>
>>
>> Thierry
>>
>> -
>>
>>
>>
>> PS: (I am not sure if my previous message went through as I was still
>> in the mailing list registration process, apologies if it is a
>> duplicate)
>>
>>
>>
>> Full code:
>>
>>
>>
>> import org.codehaus.groovy.control.CompilerConfiguration;
>>
>> import
>> org.codehaus.groovy.control.customizers.ASTTransformationCustomizer;
>>
>>
>>
>> import groovy.lang.Binding;
>>
>> import groovy.lang.Closure
>>
>> import groovy.lang.GroovyClassLoader;
>>
>> import groovy.lang.GroovyShell;
>>
>> import groovy.transform.CompileStatic;;
>>
>>
>>
>> abstract class GroovyDemoScript extends Script
>>
>> {
>>
>> public String x;
>>
>>
>>
>> public GroovyDemoScript()
>>
>> {
>>
>> x='one';
>>
>> System.out.println("init x: " + x);
>>
>> }
>>
>>
>>
>> public static void main(String...args) throws Throwable
>>
>> {
>>
>> ////
>>
>> // Compilation configuration
>>
>> CompilerConfiguration configuration = new
>> CompilerConfiguration();
>>
>> configuration.addCompilationCustomizers(new
>> ASTTransformationCustomizer(CompileStatic.class));
>>
>>
>>
>> // make sure we use the Java base
>> class where ‘x’ is defined
>>
>>
>> configuration.setScriptBaseClass(GroovyDemoScript.class.name);
>>
>>
>>
>> GroovyShell shell = new
>> GroovyShell(this.getClass().getClassLoader(), new Binding(),
>> configuration);
>>
>>
>>
>> // source code
>>
>> String scriptSource= "println '1 = ' + x; x = 'two';
>> println '2 = ' + x\n";
>>
>>
>>
>> // compile the source code and run the compiled script
>>
>> GroovyDemoScript compiledScript =
>> shell.parse(scriptSource);
>>
>> compiledScript.run();
>>
>> }
>>
>> }
>>
>>
>>
>> ________________________________
>>
>> Switchboard: +44 (0)113 394 6020
>>
>> Technical Support: +44 (0)113 394 6030
>>
>> ________________________________
>>
>> Lhasa Limited, a not-for-profit organisation, promotes scientific knowledge & understanding through the development of computer-aided reasoning & information systems in chemistry & the life sciences. Registered Charity Number 290866. Registered Office: Granary Wharf House, 2 Canal Wharf, Leeds, LS11 5PS. Company Registration Number 01765239. Registered in England and Wales.
>>
>> This communication, including any associated attachments, is intended for the use of the addressee only and may contain confidential, privileged or copyright material. If you are not the intended recipient, you must not copy this message or attachment or disclose the contents to any other person. If you have received this transmission in error, please notify the sender immediately and delete the message and any attachment from your system. Except where specifically stated, any views expressed in this message are those of the individual sender and do not represent the views of Lhasa Limited. Lhasa Limited cannot accept liability for any statements made which are the sender's own. Lhasa Limited does not guarantee that electronic communications, including any attachments, are free of viruses. Virus scanning is recommended and is the responsibility of the recipient.
>>
>> ________________________________
>>
>> This email message and any attachments are for the sole use of the intended recipient(s). Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message and any attachments.
RE: Failing to change the value of a Java variable from wihtin a
Groovy script (potential issue?)
Posted by Thierry Hanser <Th...@lhasalimited.org>.
Thank you for the suggestion Dinko.
I tried your experiment and the binding variables set remains actually empty ([:]) which is what I expected since there is no explicit binding involved (the variable 'x' is directly declared in the base script which is the point of the approach)
An interesting hint to the problem is that if I explicitly implement the getter and don't have a setter, there will be indeed an expected 'can't change a read-only value' compilation error which means that the getter/setter status is correctly analysed in the compilation decision tree and the setter must be present (or implicit) in order to allow the assignment in line 2 (x = 'two'); the problem is that it is not invoked at runtime; i.e. at compilation time Groovy's understanding is correct but the compiled code does not actually invoke the setter.
This is disturbing and concerning as it leads to unpredictable behaviour.
Thierry
-----Original Message-----
From: Dinko Srkoč [mailto:dinko.srkoc@gmail.com]
Sent: 08 March 2016 18:20
To: users@groovy.apache.org
Subject: Re: Failing to change the value of a Java variable from wihtin a Groovy script (potential issue?)
On 8 March 2016 at 18:11, Thierry Hanser <Th...@lhasalimited.org> wrote:
>
> Thank you Jason, you were indeed right, without CompileStatic or using TypeChecked works.
Well, it works, but probably not the way you think it works. Here's what you can do to get more insight into what's going on:
* print the script's variable bindings - add to `scriptSource`:
`println binding.variables`
* access the field `x` directly - to `JavaScriptDemo` add a method like this:
public String myX() { return x; }
then print that as well: `println myX()`
* run the script with and without `CompileStatic` and compare the results
After running the experiment you'll probably notice that the field `x` is never really changed. When you try to add the value 'two' to `x` you're actually creating a new binding variable. The difference with CompileStatic is in accessing the field or the binding if binding exists.
Cheers,
Dinko
>
> This is concerning as I would prefer static compilation (type checking being a must).
>
>
>
> I can work around the issue in my context but it impacts the elegance of the underlying DSL.
>
> However from the Groovy script engine perspective it is more concerning.
>
>
>
> Maybe Cedric or Guy know if there are any known issues and planned fixes related to that problem?
>
>
>
> Thanks again Jason.
>
>
>
> Thierry
>
>
>
> ---
>
> PS: There was a couple of typos in the source code (never post-edit in outlook ;-) ). Apologies for any inconveniences.
>
> Here is the correct adjusted and working code:
>
>
>
> import org.codehaus.groovy.control.CompilerConfiguration;
>
> import
> org.codehaus.groovy.control.customizers.ASTTransformationCustomizer;
>
>
>
> import groovy.lang.Binding;
>
> import groovy.lang.GroovyShell;
>
> import groovy.lang.Script;
>
> import groovy.transform.CompileStatic;;
>
>
>
> public abstract class JavaScriptDemo extends Script
>
> {
>
> public String x;
>
>
>
> public JavaScriptDemo()
>
> {
>
> x="one";
>
> System.out.println("init x: " + x);
>
> }
>
>
>
> /**
>
> * Demo main
>
> * @param args
>
> * @throws Throwable
>
> */
>
> public static void main(String...args) throws Throwable
>
> {
>
> ////
>
> // Compilation configuration
>
> CompilerConfiguration configuration = new
> CompilerConfiguration();
>
> configuration.addCompilationCustomizers(new
> ASTTransformationCustomizer(CompileStatic.class));
>
>
> configuration.setScriptBaseClass(JavaScriptDemo.class.getName());
>
> GroovyShell shell = new
> GroovyShell(JavaScriptDemo.class.getClassLoader(), new Binding(),
> configuration);
>
>
>
> // source code
>
> String scriptSource= "println '1 = ' + x; x = 'two';
> println '2 = ' + x\n";
>
>
>
> // compile the source code and run the compiled script
>
> JavaScriptDemo compiledScript =
> (JavaScriptDemo)shell.parse(scriptSource);
>
> compiledScript.run();
>
> }
>
> }
>
>
>
> From: Winnebeck, Jason [mailto:Jason.Winnebeck@windstream.com]
> Sent: 08 March 2016 16:46
> To: users@groovy.apache.org
> Subject: RE: Failing to change the value of a Java variable from
> wihtin a Groovy script (potential issue?)
>
>
>
> Unfortunately static compile can be pretty flaky at times and I run into bugs often with it and have to redesign code. For small scripts I would advise against it (if you need type checking, use TypeChecked). I’m wondering if the script is getting compiled to get field x from the base class but favors setting binding.x = ‘two’ in the script.
>
>
>
> I would try without static compilation and see if it works. If it does work without static compilation, upgrade to the very latest Groovy (2.4.6) as bugs are fixed in static compiler all the time. If that doesn’t fix the problem, then change the Java field to private and create a getX() and setX(String). If that doesn’t work and you still need static compile, try an explicit setX(‘two’) or this.x = ‘two’ in the script. Historically the static compiler has been more reliable when you are more explicit.
>
>
>
> Jason
>
>
>
> From: Thierry Hanser [mailto:Thierry.Hanser@lhasalimited.org]
> Sent: Tuesday, March 08, 2016 11:32 AM
> To: 'users@groovy.apache.org' <us...@groovy.apache.org>
> Subject: Failing to change the value of a Java variable from wihtin a
> Groovy script (potential issue?)
>
>
>
> Hi,
>
>
>
> The following very simple code is behaving really strangely.
>
> Could anyone please tell me if this is an issue in Groovy or something I am not doing properly (I would like to vote for the latter, yet...).
>
>
>
> In Java
>
>
>
> x='one';
>
> System.out.println("init x: " + x);
>
>
>
> In Groovy
>
>
>
> println '1 = ' + x
>
> x = 'two'
>
> println '2 = ' + x
>
>
>
> Output:
>
>
>
> init x: one <- initial value assignement OK
>
>
>
> 1 = one <- successfully accessing ‘x’ from within the compiled script OK
>
> the Groovy script has picked up the value of the Java
> variable;
>
> the implicit getX() has been called
>
>
>
> 2 = one <- should be ‘two’ as per Groovy code (second line)
>
> but is unchanged ???
>
>
>
> It seems that the Groovy script can’t change the value of ‘x’ (can’t
> access setX()). However there is no compilation error (‘x’ is not
> read-only)
>
> When implementing getX/setX methods, only the getter is called (in both print statements, line 1,3) but during the assignment instruction (line 2), the setter is silently ignored (the value of ‘x’ remains ‘one’ instead of ‘two’.
>
>
>
> The Java/Groovy binding is operational since the ‘one’ value of ‘x’ in the Java base class is successfully retrieved. So could anyone please tell me where the issue is?
>
> The confusing part is that even within in the Groovy context alone,
> the assignment ‘x=’two’ is not honoured (and yet there are no
> compilation/runtime error)
>
>
>
> Note that I tried all combinations of setters/getters/visibility and
> can at the best read but never modify the variable ‘x’. The same
> behaviour occurs with using the GroovyScriptEngine or
> GroovyClassLoader
>
>
>
> Thank you very much in advance for your help.
>
>
>
> Thierry
>
> -
>
>
>
> PS: (I am not sure if my previous message went through as I was still
> in the mailing list registration process, apologies if it is a
> duplicate)
>
>
>
> Full code:
>
>
>
> import org.codehaus.groovy.control.CompilerConfiguration;
>
> import
> org.codehaus.groovy.control.customizers.ASTTransformationCustomizer;
>
>
>
> import groovy.lang.Binding;
>
> import groovy.lang.Closure
>
> import groovy.lang.GroovyClassLoader;
>
> import groovy.lang.GroovyShell;
>
> import groovy.transform.CompileStatic;;
>
>
>
> abstract class GroovyDemoScript extends Script
>
> {
>
> public String x;
>
>
>
> public GroovyDemoScript()
>
> {
>
> x='one';
>
> System.out.println("init x: " + x);
>
> }
>
>
>
> public static void main(String...args) throws Throwable
>
> {
>
> ////
>
> // Compilation configuration
>
> CompilerConfiguration configuration = new
> CompilerConfiguration();
>
> configuration.addCompilationCustomizers(new
> ASTTransformationCustomizer(CompileStatic.class));
>
>
>
> // make sure we use the Java base
> class where ‘x’ is defined
>
>
> configuration.setScriptBaseClass(GroovyDemoScript.class.name);
>
>
>
> GroovyShell shell = new
> GroovyShell(this.getClass().getClassLoader(), new Binding(),
> configuration);
>
>
>
> // source code
>
> String scriptSource= "println '1 = ' + x; x = 'two';
> println '2 = ' + x\n";
>
>
>
> // compile the source code and run the compiled script
>
> GroovyDemoScript compiledScript =
> shell.parse(scriptSource);
>
> compiledScript.run();
>
> }
>
> }
>
>
>
> ________________________________
>
> Switchboard: +44 (0)113 394 6020
>
> Technical Support: +44 (0)113 394 6030
>
> ________________________________
>
> Lhasa Limited, a not-for-profit organisation, promotes scientific knowledge & understanding through the development of computer-aided reasoning & information systems in chemistry & the life sciences. Registered Charity Number 290866. Registered Office: Granary Wharf House, 2 Canal Wharf, Leeds, LS11 5PS. Company Registration Number 01765239. Registered in England and Wales.
>
> This communication, including any associated attachments, is intended for the use of the addressee only and may contain confidential, privileged or copyright material. If you are not the intended recipient, you must not copy this message or attachment or disclose the contents to any other person. If you have received this transmission in error, please notify the sender immediately and delete the message and any attachment from your system. Except where specifically stated, any views expressed in this message are those of the individual sender and do not represent the views of Lhasa Limited. Lhasa Limited cannot accept liability for any statements made which are the sender's own. Lhasa Limited does not guarantee that electronic communications, including any attachments, are free of viruses. Virus scanning is recommended and is the responsibility of the recipient.
>
> ________________________________
>
> This email message and any attachments are for the sole use of the intended recipient(s). Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message and any attachments.