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From Zaxebo Yaxebo <>
Subject Re: chdir() implementation requested in groovy, just like jruby
Date Mon, 06 Jul 2015 00:47:11 GMT
Thanks for the feedback.

Those users like me, who want to use groovy for scripting for Operating
system domain, and replace shellscript/ruby/python scripts with the one
"groovy" language script there. We obviously need changeDirectory(chdir())
function. This is the case of missing of "only one very core filesystem
manipulation function (chdir) from groovy-gdk".

As you said, why - "it will depend upon env. framework and alot of
variables that need to be set by a developer creating a required config
over convention functionality".???
if JNA method for chdir() is finalised, then it only requires almost the
following code:

import com.sun.jna.NativeLibrary;

import com.sun.jna.Platform;


   - Call native low level Posix functions.
   public class Posix
   private static final int MAX_PATH = 1024;
   private NativeLibrary cLib = null;
   public void chdir(String dirName)
   Unknown macro: { int error =
   getCLib().getFunction(getOsDependentFuntionName("chdir")).invokeInt( new
   Object[] { dirName }); if (error != 0) throw new Error("Could not change
   working directory to}

   private NativeLibrary getCLib()
   { if (cLib == null) cLib = NativeLibrary.getInstance(null); // Will load or msvcrt.dll return cLib; }

   public String getcwd()
   Unknown macro: { String cwd =
   new Object[] { new String(new byte[MAX_PATH]), MAX_PATH }, false); return
   cwd; }

   private String getOsDependentFuntionName(String fname)
   { if (Platform.isWindows()) return "_" + fname; return fname; }


In single threaded environments like shell scripting, it is really very
stable and rocks solid.

alternative proposal:
Though i would pray that this feature of chdir() is implemented.
But, Just in case, this chdir() function is not implemented , i would still
suggest/request* that atleast JNA or JNR .jar to be bundled with groovy*,
so that user can access large native functionality without writing JNI
code. The entire JNA/JNR end-user's source code will always be in
java/groovy. It will replace lot of C/C++ coding of JNI. Say,It will enable
user to access extended file system attributes (say for XFS,/proc type file
systems) directly from native functions, for those file systems for which
java driver is not there. It will let us access other Posix API or native
Win32 API functions etc , directly from java/groovy code without writing
glue C/C++ JNI code.
This native accessing  functionality without writing glue C/C++ code, will
let groovy core  reach extend to lots of native functionality.

Probably, those who are into Web development etc may not need it. But those
like us who want to communicate to other native accessing functionality
without compiling any .so on their own,  we want to use groovy for
scripting these cases also. Groovy can atleast provide JNA/JNR
functionality out of the box, to enable large native functionality access
out of the box, for which there is no inbuilt functionality in jdk.


On Mon, Jul 6, 2015 at 2:28 AM, Owen Rubel <> wrote:

> Well... The only thing really competing with JRuby is Ruby.
> Groovy isn't a bridge for another language which is why it's approx 4x
> faster than JRuby.
> It's purpose isn't to mock every other language but to implement
> convention over config concepts, provide a scripting language for Java,
>  simplified functions.
> The chdir() function really really depends on env, framework and alot of
> variables that need to be set by a developer creating a required config
> over convention functionality. You CAN automate it but you lose speed when
> running over simplicity.
> I think thats why it won't be implemented IMHO.
> Owen Rubel
> 415-971-0976
> On Sun, Jul 5, 2015 at 11:26 AM, Zaxebo Yaxebo <> wrote:
>> jvm has no chdir() function to change current working directory.
>> As groovy positions itself as competitor to jruby and other scripting
>> language, and jruby implements chdir() using JNR (not using JNI)
>> jython also implements chdir() on its own, but its implementation has
>> some limtation. And jruby's implementation of chdir() function is best and
>> stable.
>> I have filed an enhancement request of adding a chdir() function to
>> groovy using JNA or JNR.
>> I have given sample code to achieve this using JNA.
>> please give your feedback at
>> for this enhancement feature request.
>> zaxebo1

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