What is this expected to return?

time = {
    it()
}

Initially, my example was a bit bigger, as it was a "timing" closure:

time = {
def start = System.currentTimeMillis()
it()
println System.currentTimeMillis() - start
}

This closure is handy, because you can use it to measure the time something takes like so:

time { /* do something that takes some time */ }

But I reduced this example to its simplest expression with time = { it() }
When everything is on the same line, it just works, but when it's spanning three lines, it fails with the huge stacktrace above.

So, it's not so much that I expect this to return something, but I just wanted to put that closure in the variable binding, so that I can reuse this timing closure to measure some things that took time to execute.

In my last comment, I mentioned time = { it() } worked when everything was on the same line, but it's false, whether it's on a single line or spanning several lines, it throws a huge stacktrace.

And this does work as expected in the old shell na?

Yup, you can check it by resetting your NEWSHELL env variable to void.
It does work with the old shell, but not with the new.

The problem is that the generated groovysh_evaluate$_run_closure1 does not have a reasonable toString() so when we log the result it pukes this up. Looking into solutions...

Should be fixed now

I still get the issue after updating:

C:\oss\groovy-core>groovysh
Groovy Shell (1.1-rc-1-SNAPSHOT, JVM: 1.6.0_02-b06)
Type 'help' or '\h' for help.
-------------------------------------------------------------------------------------------------------------
groovy:000> time = { ===> null groovy:001> it() ===> null groovy:002> }

001> time = { 002> it() 003> }

ERROR groovy.lang.MissingMethodException: No signature of method: java.io.StringWriter.doCall() is applicable
for argument types: () values: {}
at groovy.lang.MetaClassImpl.invokeMissingMethod (MetaClassImpl.java:562)
at groovy.lang.MetaClassImpl.invokeMissingMethod (MetaClassImpl.java:538)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:775)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:602)
at org.codehaus.groovy.runtime.Invoker.invokePojoMethod (Invoker.java:87)
at org.codehaus.groovy.runtime.Invoker.invokeMethod (Invoker.java:75)
at org.codehaus.groovy.runtime.InvokerHelper.invokeMethod (InvokerHelper.java:74)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodN (ScriptBytecodeAdapter.java:158)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeClosure (ScriptBytecodeAdapter.java:612)
at groovysh_evaluate$_run_closure1.doCall (groovysh_evaluate:2)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke (Method.java:597)
at org.codehaus.groovy.reflection.CachedMethod.invokeByReflection (CachedMethod.java:107)
at org.codehaus.groovy.runtime.metaclass.ReflectionMetaMethod.invoke (ReflectionMetaMethod.java:58)
at org.codehaus.groovy.runtime.MetaClassHelper.doMethodInvoke (MetaClassHelper.java:537)
at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod (ClosureMetaClass.java:219)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:602)
at groovy.lang.Closure.call (Closure.java:293)
at groovy.lang.GString.writeTo (GString.java:155)
at groovy.lang.GString.toString (GString.java:133)
at org.codehaus.groovy.reflection.CachedClass.coerceGString (CachedClass.java:183)
at org.codehaus.groovy.reflection.ParameterTypes.coerceArgumentsToClasses (ParameterTypes.java:107)
at org.codehaus.groovy.runtime.MetaClassHelper.doMethodInvoke (MetaClassHelper.java:535)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:760)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:602)
at org.codehaus.groovy.runtime.Invoker.invokePojoMethod (Invoker.java:87)
at org.codehaus.groovy.runtime.Invoker.invokeMethod (Invoker.java:75)
at org.codehaus.groovy.runtime.InvokerHelper.invokeMethod (InvokerHelper.java:74)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodN (ScriptBytecodeAdapter.java:158)
at org.codehaus.groovy.tools.shell.Groovysh.setLastResult (Groovysh.groovy:93)
at org.codehaus.groovy.tools.shell.Groovysh.this$3$setLastResult (Groovysh.groovy)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke (Method.java:597)
at org.codehaus.groovy.reflection.CachedMethod.invokeByReflection (CachedMethod.java:107)
at org.codehaus.groovy.runtime.metaclass.ReflectionMetaMethod.invoke (ReflectionMetaMethod.java:58)
at org.codehaus.groovy.runtime.MetaClassHelper.doMethodInvoke (MetaClassHelper.java:537)
at groovy.lang.MetaClassImpl.setProperty (MetaClassImpl.java:1763)
at groovy.lang.MetaClassImpl.setProperty (MetaClassImpl.java:2428)
at sun.reflect.GeneratedMethodAccessor11.invoke (Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke (Method.java:597)
at org.codehaus.groovy.reflection.CachedMethod.invokeByReflection (CachedMethod.java:107)
at org.codehaus.groovy.reflection.CachedMethod.invoke (CachedMethod.java:127)
at org.codehaus.groovy.runtime.metaclass.StdMetaMethod.invoke (StdMetaMethod.java:18)
at org.codehaus.groovy.runtime.MetaClassHelper.doMethodInvoke (MetaClassHelper.java:537)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:760)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:602)
at org.codehaus.groovy.runtime.Invoker.invokePojoMethod (Invoker.java:87)
at org.codehaus.groovy.runtime.Invoker.invokeMethod (Invoker.java:75)
at org.codehaus.groovy.runtime.InvokerHelper.invokeMethod (InvokerHelper.java:74)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodN (ScriptBytecodeAdapter.java:158)
at org.codehaus.groovy.tools.shell.Shell.setProperty (Shell.groovy)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.setGroovyObjectProperty (ScriptBytecodeAdapter.ja
va:571)
at org.codehaus.groovy.tools.shell.Groovysh.execute (Groovysh.groovy:183)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke (Method.java:597)
at org.codehaus.groovy.reflection.CachedMethod.invokeByReflection (CachedMethod.java:107)
at org.codehaus.groovy.reflection.CachedMethod.invoke (CachedMethod.java:127)
at org.codehaus.groovy.runtime.metaclass.StdMetaMethod.invoke (StdMetaMethod.java:18)
at org.codehaus.groovy.runtime.MetaClassHelper.doMethodInvoke (MetaClassHelper.java:537)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:760)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnCurrentN (ScriptBytecodeAdapter.jav
a:66)
at org.codehaus.groovy.tools.shell.Shell.leftShift (Shell.groovy:121)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke (Method.java:597)
at org.codehaus.groovy.reflection.CachedMethod.invokeByReflection (CachedMethod.java:107)
at org.codehaus.groovy.reflection.CachedMethod.invoke (CachedMethod.java:127)
at org.codehaus.groovy.runtime.metaclass.StdMetaMethod.invoke (StdMetaMethod.java:18)
at org.codehaus.groovy.runtime.MetaClassHelper.doMethodInvoke (MetaClassHelper.java:537)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:760)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:602)
at org.codehaus.groovy.runtime.Invoker.invokePogoMethod (Invoker.java:98)
at org.codehaus.groovy.runtime.Invoker.invokeMethod (Invoker.java:79)
at org.codehaus.groovy.runtime.InvokerHelper.invokeMethod (InvokerHelper.java:74)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodN (ScriptBytecodeAdapter.java:158)
at org.codehaus.groovy.tools.shell.ShellRunner.work (ShellRunner.groovy:88)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke (Method.java:597)
at org.codehaus.groovy.reflection.CachedMethod.invokeByReflection (CachedMethod.java:107)
at org.codehaus.groovy.runtime.metaclass.ReflectionMetaMethod.invoke (ReflectionMetaMethod.java:58)
at org.codehaus.groovy.runtime.MetaClassHelper.doMethodInvoke (MetaClassHelper.java:537)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:760)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnCurrentN (ScriptBytecodeAdapter.jav
a:66)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnCurrent0 (ScriptBytecodeAdapter.jav
a:99)
at org.codehaus.groovy.tools.shell.ShellRunner.run (ShellRunner.groovy:57)
at org.codehaus.groovy.tools.shell.InteractiveShellRunner.super$2$run (InteractiveShellRunner.groovy)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke (Method.java:597)
at org.codehaus.groovy.reflection.CachedMethod.invokeByReflection (CachedMethod.java:107)
at org.codehaus.groovy.runtime.metaclass.ReflectionMetaMethod.invoke (ReflectionMetaMethod.java:58)
at org.codehaus.groovy.runtime.MetaClassHelper.doMethodInvoke (MetaClassHelper.java:537)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:760)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN (ScriptBytecodeAdapter.java:
118)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuper0 (ScriptBytecodeAdapter.java:
142)
at org.codehaus.groovy.tools.shell.InteractiveShellRunner.run (InteractiveShellRunner.groovy:64)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke (Method.java:597)
at org.codehaus.groovy.reflection.CachedMethod.invokeByReflection (CachedMethod.java:107)
at org.codehaus.groovy.reflection.CachedMethod.invoke (CachedMethod.java:127)
at org.codehaus.groovy.runtime.metaclass.StdMetaMethod.invoke (StdMetaMethod.java:18)
at org.codehaus.groovy.runtime.MetaClassHelper.doMethodInvoke (MetaClassHelper.java:537)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:760)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:602)
at org.codehaus.groovy.runtime.Invoker.invokePogoMethod (Invoker.java:98)
at org.codehaus.groovy.runtime.Invoker.invokeMethod (Invoker.java:79)
at org.codehaus.groovy.runtime.InvokerHelper.invokeMethod (InvokerHelper.java:74)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodN (ScriptBytecodeAdapter.java:158)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethod0 (ScriptBytecodeAdapter.java:201)
at org.codehaus.groovy.tools.shell.Groovysh.run (Groovysh.groovy:461)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke (Method.java:597)
at org.codehaus.groovy.reflection.CachedMethod.invokeByReflection (CachedMethod.java:107)
at org.codehaus.groovy.reflection.CachedMethod.invoke (CachedMethod.java:127)
at org.codehaus.groovy.runtime.metaclass.StdMetaMethod.invoke (StdMetaMethod.java:18)
at org.codehaus.groovy.runtime.MetaClassHelper.doMethodInvoke (MetaClassHelper.java:537)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:760)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnCurrentN (ScriptBytecodeAdapter.jav
a:66)
at org.codehaus.groovy.tools.shell.Groovysh.run (Groovysh.groovy:402)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke (Method.java:597)
at org.codehaus.groovy.reflection.CachedMethod.invokeByReflection (CachedMethod.java:107)
at org.codehaus.groovy.reflection.CachedMethod.invoke (CachedMethod.java:127)
at org.codehaus.groovy.runtime.metaclass.StdMetaMethod.invoke (StdMetaMethod.java:18)
at org.codehaus.groovy.runtime.MetaClassHelper.doMethodInvoke (MetaClassHelper.java:537)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:760)
at groovy.lang.MetaClassImpl.invokeMethod (MetaClassImpl.java:602)
at org.codehaus.groovy.runtime.Invoker.invokePogoMethod (Invoker.java:98)
at org.codehaus.groovy.runtime.Invoker.invokeMethod (Invoker.java:79)
at org.codehaus.groovy.runtime.InvokerHelper.invokeMethod (InvokerHelper.java:74)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodN (ScriptBytecodeAdapter.java:158)
at org.codehaus.groovy.tools.shell.Groovysh.main (Groovysh.groovy:561)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke (Method.java:597)
at org.codehaus.groovy.tools.GroovyStarter.rootLoader (GroovyStarter.java:101)
at org.codehaus.groovy.tools.GroovyStarter.main (GroovyStarter.java:130)
groovy:000>

Looks like there are a few more places where a gstring is used to output the result, which causes this to barf. I'm digging thme up... and using String.valueOf() instead which resolves this problem.

I've found a few other places where this might pop up... but you an still make this happen with:

time = { it() }
println "$time"

Though this works fine:

time = { it() }
println time

My guess is there is another deeper bug in here... but ATM I'm not sure what the fix is.