[Baypiggies] os.path.join unexpected behavior on windows

[Chris Clark]

Please excuse my top post.

I've had this issue too, I never worked out why, I just stick an 
os.path.abspath() around everything I want to display (using it as-is 
with the Python libs is fine, display is the only place it matters). E.g.

     >>> import os
     >>> os.path.abspath('m:/billdeeg.scons1\\build')
    'm:\\billdeeg.scons1\\build'
     >>>

and pretend it doesn't happen :-)

HTH

Chris

On 8/26/2008 5:02 PM, William Deegan wrote:
> Greetings,
>
> I have the following (simplified) code:
> import os.path
>
> z='/build'
> x='m:/billdeeg.scons1'
> print  "X=>%-20s z=>%-10s Joined path is=>%s"%(x,z,os.path.join(x,z))
>
> x='m:/billdeeg.scons1/'
> print  "X=>%-20s z=>%-10s Joined path is=>%s"%(x,z,os.path.join(x,z))
>
> x='m:/billdeeg.scons1'
> print  "X=>%-20s z=>%-10s Joined path is=>%s"%(x,z,os.path.join(x,z))
>
> z='build'
> print  "X=>%-20s z=>%-10s Joined path is=>%s"%(x,z,os.path.join(x,z))
>
> z='/build'
> x='n:'
> print  "X=>%-20s z=>%-10s Joined path is=>%s"%(x,z,os.path.join(x,z))
>
> x='n:/'
> print  "X=>%-20s z=>%-10s Joined path is=>%s"%(x,z,os.path.join(x,z))
>
> x='m:/billdeeg.scons1'
> print  "X=>%-20s z=>%-10s Joined path is=>%s"%(x,z,os.path.join(x,z))
>
>
>
> When I run it I get the following output:
> C:\cygwin\home\billdeeg\tmp>python try_ospathjoin.py
> X=>m:/billdeeg.scons1   z=>/build     Joined path is=>/build
> X=>m:/billdeeg.scons1/  z=>/build     Joined path is=>/build
> X=>m:/billdeeg.scons1   z=>/build     Joined path is=>/build
> X=>m:/billdeeg.scons1   z=>build      Joined path is=>m:/billdeeg.scons1\build
> X=>n:                   z=>/build     Joined path is=>n:/build
> X=>n:/                  z=>/build     Joined path is=>n:/build
> X=>m:/billdeeg.scons1   z=>/build     Joined path is=>/build
>
>
> I would expect in all cases that I would get :
> n:/build or m:/billdeeg.scons1/build
> But as you can see in some cases that's not what I get.
>
> Here's the docs about os.path.join:
> join( path1[, path2[, ...]])
>
> Join one or more path components intelligently. If any component is an
> absolute path, all previous components (on Windows, including the
> previous drive letter, if there was one) are thrown away, and joining
> continues. The return value is the concatenation of path1, and
> optionally path2, etc., with exactly one directory separator (os.sep)
> inserted between components, unless path2 is empty. Note that on
> Windows, since there is a current directory for each drive,
> os.path.join("c:", "foo") represents a path relative to the current
> directory on drive C: (c:foo), not c:\\foo.
>
> I'm guessing I get : /build in because of the clause above about "if
> any component is an absolute path...", is that correct?
>
> So to get what I expect, looks like I need to insure that none of the
> [1:] arguments start with a '/' or '\' ?
>
> Thanks,
> Bill
> _______________________________________________
> Baypiggies mailing list
> Baypiggies at python.org
> To change your subscription options or unsubscribe:
> http://mail.python.org/mailman/listinfo/baypiggies
>