[jira] [Updated] (CASSANDRA-4090) cqlsh can't handle python being a python3

["paul cannon (Updated) (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-4090?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

paul cannon updated CASSANDRA-4090:
-----------------------------------

    Attachment: 4090.patch.txt

I would argue that Archlinux is the broken one, in this respect: nearly everything executable in the Python ecosystem still expects an unqualified "python" to be python2.

But oh well. This is an easy improvement to make. The logic in the original patch is backward; you want sys.exit to exit with False when the version is good (since False becomes 0, which shell treats as success). Adjusted a little for brevity and inverted logic.
                
> cqlsh can't handle python being a python3
> -----------------------------------------
>
>                 Key: CASSANDRA-4090
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4090
>             Project: Cassandra
>          Issue Type: Bug
>    Affects Versions: 1.0.8
>         Environment: On Archlinux, where Python3 installations are default (most distros currently use Python2 as default now)
> {code}
> $ ls -l `which python` 
> lrwxrwxrwx 1 root root 7 Nov 21 09:05 /usr/bin/python -> python3
> {code}
>            Reporter: Andrew Ash
>            Assignee: Andrew Ash
>         Attachments: 4090.patch.txt, python3-fix.patch
>
>
> cqlsh fails to run when {{python}} is a Python 3, with this error message:
> {code}
> andrew@spite:~/src/cassandra-trunk/bin $ ./cqlsh 
>   File "./cqlsh", line 97
>     except ImportError, e:
>                       ^
> SyntaxError: invalid syntax
> andrew@spite:~/src/cassandra-trunk/bin $ 
> {code}
> The error occurs because the cqlsh script checks for a default installation of python that is older than a certain version, but not one newer that is incompatible (e.g. Python3).  To fix this, I update the logic to only run {{python}} if it's a version at least 2.5 but before 3.0  If this version of python is in that range then role with it, otherwise try python2.6, python2.7, then python2.5 (no change from before).
> This is working on my installation, where {{python}} executes python 3.2.2 and doesn't break backwards compatibility to distributions that haven't made the jump to Python3 as default yet.

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