Directory handling

[Marco Antoniotti]

Hi



> On Jun 11, 2019, at 11:33 , Mark Evenson <evenson at panix.com> wrote:
> 
> 
> 
>> On Jun 5, 2019, at 17:53, Marco Antoniotti <marco.antoniotti at unimib.it> wrote:
>> 
>> Dear all,
>> 
>> I have been looking at the ABCL manual and packages and I was not able (my fault!) to find functions like CURRENT-DIRECTORY and/or CHANGE-DIRECTORY (or CHDIR).
>> 
>> Could you tell me how to get to this functionality?
> 
> Unfortunately, the JVM doesn’t have a [standard interface to change the working directory][1] there is no direct method to setting the current working directory.  The JVM gets a copy of the system environment variables including the current working directory
> 
> [1]: https://stackoverflow.com/questions/840190/changing-the-current-working-directory-in-java

Ok.  Thanks.  Understood.  So this is a Java “feature”.

> It would help to know more specifically what you wish to do after changing the directory, but here’s a guess at what you may wish to do:
> 
> If you wish invoke purely Lisp-side functionality, then use the value of CL:*DEFAULT-PATHNAMES-DEFAULTS*, which is what UIOP/OS:GETCWD returns.  

That is what I fall back to.  I was just wondering if there was a “to-the-file-system” primitive.  *D-P-D* munging will do.

> If you wish to fork processes in another directory then the specify the relavant argument to  UIOP/RUN-PROGRAM:RUN-PROGRAM.  
> 
> In very pathlogical cases you may have to write a script that ensures the JVM hosting ABCL is started in the directory you wish to have as the current directory.  I had to do this in order to get a Minecraft server to run under ABCL.

Ok.  Nothing of the kind is really needed.





> 
>> Also, what is the set of features that ABCL uses to identify the platform?  On a Mac OSX I see (at a minimum):
>> 
>> :SWANK 
>> :X86-64 
>> :UNIX 
>> :DARWIN 
>> :ARMEDBEAR 
>> :ABCL 
>> :COMMON-LISP 
>> :ANSI-CL 
>> :CDR6 
>> :MOP 
>> :PACKAGE-LOCAL-NICKNAMES 
>> NIL
>> 
> 
> The code which sets platform features is the [best source of what keywords identify which plaform features][2].  Additionaly, there is (incomplete) support for identifying the JVM version by the use of the :java-1.6, :java-1.7, and :java—1.8 keywords.  Again, it would be helpful to know what sort of platform features you wish to detect. 
> 
> 
> [2]: https://abcl.org/trac/browser/trunk/abcl/src/org/armedbear/lisp/Lisp.java#L2362

Thanks.  I just wanted to know what set of features I can use to know that I am running on a Mac OS X or, say, a Windows 10.  It looks like that (and :UNIX :DARWIN) is what I need for Mac OS X and WINDOWS for all Windows.

Thanks

Marco

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