Find parent directory of file

[cormullion]

Given a file coming in through the command line:

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(set 'f (main-args 2))

How can I find out what the directory of it is so that I can set the current directory to it?

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(change-dir ... f)

The only thing I can see to do is to parse the filename, which seems like the non-newLISP way...

[Lutz]

you could use real-path to get the full path and then isolate the path chopping off the filename from the end:

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(join (chop (parse (real-path (main-args 2)) "/")) "/")


Lutz

[cormullion]

Thanks, Lutz! I was trying things like parse and even stuff like:

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(reverse (member "/" (reverse (real-path f) )))

Yours looks more sensible.



I can imagine a more elegant solution one day - like if change-dir accepted a filename and found the containing directory ...

[Sammo]

Following Lutz's lead, in Windows I can define:

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(define (.. f)
  (join (chop (parse (real-path f) "\") 2) "\") )

(define (. f)
  (join (chop (parse (real-path f) "\") 1) "\") )

Then execute:

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(change-dir (.. "c:\path1\path2\path3\filename.txt"))

to change the directory focus to c:/path1/path2, or:

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(change-dir (. "c:\path1\path2\path3\filename.txt"))

to change the directory focus to c:/path1/path2/path3.



Something along these lines might be the ticket.

[cormullion]

Hi Sammo - nice to see you round here! I hadn't thought about the Windows backslash. Doesn't Windows now accept forward slashes? (Sorry I rarely use it at the moment.) So a generic function would be harder.



I like the idea of defining '..' and '.' as functions...