I cannot evaluate this statement...
Steven D'Aprano
steve at REMOVE-THIS-cybersource.com.au
Fri Mar 7 16:25:48 EST 2008
On Fri, 07 Mar 2008 12:38:11 -0800, waltbrad wrote:
> The script comes from Mark Lutz's Programming Python. It is the second
> line of a script that will launch a python program on any platform.
>
> import os, sys
> pyfile = (sys.platform[:3] == 'win' and 'python.exe') or 'python'
>
> Okay, run on a win32 machine, pyfile evaluates to python.exe
>
> That makes sense. Because the first condition is true and 'python.exe'
> is true. So the next comparison is 'python.exe' or 'python' Well,
> python.exe is true. So that value is returned to pyfile.
>
> Now. Run this on linux. The first condition evaluates sys.platform[:3]
> == 'win' as false. So, the next comparison should be 'False' or
> 'python' -- This is because 'and' returns the first false value. But,
> again, on linux pyfile evaluates to python.exe
Not on my Linux box.
>>> import os, sys
>>> sys.platform
'linux2'
>>> (sys.platform[:3] == 'win' and 'python.exe') or 'python'
'python'
> Where am I going wrong. And when will this statment make pyfile
> evaluate to 'python' ?
When the first three letters of sys.platform aren't 'win'.
--
Steven
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