Python variable substitution

Question

I have a script that calls a list of linux guests I am trying to tidy up. Here is the code:

#!/usr/bin/python


guests = ['guest1','guest2','guest3','guest*']
def serverCheck(guestList)
    for g in guestList:
        server = AdminControl.completeObjectName('cell=tstenvironment,node=guest1,name=uatenvironment,type=Server,*')
        try:
            status = AdminControl.getAttribute(server, 'state')
            print g + status
        except:
            print "Error %s is down." % g
serverCheck(guests)

The problem lies in this line:

server = AdminControl.completeObjectName('cell=Afcutst,node=%s,name=afcuuat1,type=Server,*') % g

How do I use my list to populate the node variable while still being able to pass the info within the parentheses to the AdminControl function?

chepner · Accepted Answer · 2016-03-17 21:10:36Z

1

The argument string itself is the argument to the % operator, not the return value of the function call.

server = AdminControl.completeObjectName(
    'cell=Afcutst,node=%s,name=afcuuat1,type=Server,*' % (g,)
)

Peeking into the crystal ball, Python 3.6 will allow you to write

server = AdminControl.completeObjectName(
    f'cell=Afcutst,node={g},name=afcuuat1,type=Server,*'
)

embedding the variable directly into a special format string literal.

edited Mar 17, 2016 at 21:10

answered Mar 17, 2016 at 20:45

chepner

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Comments

krishna rachur · Accepted Answer · 2016-03-17 21:03:13Z

0

can you try like this

AdminControl.completeObjectName('cell=tstenvironment,node=%s,name=uatenvironment,type=Server,*'%g)

answered Mar 17, 2016 at 21:03

krishna rachur

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DevLounge · Accepted Answer · 2016-03-17 21:23:47Z

0

For more readability I would suggest this and also using the same way to format strings from variables (here I chose str.format)

guests = ['guest1','guest2','guest3','guest*']

def serverCheck(guestList)
    name_tpl = 'cell=tstenvironment,node={},name=uatenvironment,type=Server,*'

    for g in guestList:
        obj_name = name_tpl.format(g)
        server = AdminControl.completeObjectName(obj_name)
        try:
            status = AdminControl.getAttribute(server, 'state')
            print '{}: {}'.format(g, status)
        except:
            print 'Error {} is down'.format(g)

serverCheck(guests)

edited Mar 17, 2016 at 21:23

answered Mar 17, 2016 at 21:11

DevLounge

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