Labelling layers with Python

Question

I need to turn labels on for previously used layer. Here is the code:

import arcpy
import sys
from arcpy import env

env.overwriteOutput = 1
gp = arcgisscripting.create(9.3)

fc_Mord = arcpy.GetParameterAsText(0)

mxd = arcpy.mapping.MapDocument("CURRENT")
layer = arcpy.mapping.ListLayers(mxd, "Mord")[0]
if layer.supports("LABELCLASSES"):
for lblClass in layer.labelClasses:
    lblClass.expression = "[ArcID]"
    layer.showLabels = True
arcpy.RefreshActiveView()
del mxd

I want to use variable fc_Mord instead of layer name Mord, because user can name the layer (in previous steps) as he/she wants.

I have tried this, but it doesn't label the layer

tempLayer = "tempLayer"
arcpy.MakeFeatureLayer_management(fc_Mord, "tempLayer")

mxd = arcpy.mapping.MapDocument("CURRENT")
layer = arcpy.mapping.ListLayers(mxd, tempLayer)[0]
if layer.supports("LABELCLASSES"):
for lblClass in layer.labelClasses:
    lblClass.expression = "[ArcID]"
    layer.showLabels = True
arcpy.RefreshActiveView()
del mxd

What am I doing wrong here?

Edited code

mxd = arcpy.mapping.MapDocument("CURRENT") #Map document reference
def label(fc_Mord, field):
   for lyr in arcpy.mapping.ListLayers(mxd):
       if lyr.name == fc_Mord:
           if lyr.supports("LABELCLASSES"):
               for lblClass in lyr.labelClasses:
                   lblClass.expression = "[ArcID]".format(field)
                   lyr.showLabels = True
arcpy.RefreshActiveView()
del mxd

Answer 1

Try using this function: i use it all the time it works great. Also you need to indent after your if layer.supports("LABELCLASSES"):

def label(layer):
    for lyr in arcpy.mapping.ListLayers(mxd):
        if lyr.name == layer:
            if lyr.supports("LABELCLASSES"):
                for lblClass in lyr.labelClasses:
                    lblClass.expression = "[ArcID]"
                    lyr.showLabels = True

you need to call the function after you initialize it

label(fc_Mord)

if you want "tempLayer" to be labeled then

label("tempLayer")

Answer 2

Try this:

import arcpy
import sys
from arcpy import env

env.overwriteOutput = 1
gp = arcgisscripting.create(9.3)
attr_name = 'Attribute Name'

fc_Mord = arcpy.GetParameterAsText(0)
mxd = arcpy.mapping.MapDocument("CURRENT") #Map document reference
def label(fc_Mord, field):
   for lyr in arcpy.mapping.ListLayers(mxd):
       if lyr.name == fc_Mord:
           if lyr.supports("LABELCLASSES"):
               for lblClass in lyr.labelClasses:
                   lblClass.expression = "[{}]".format(field)
                   lyr.showLabels = True
label(fc_Mord, attr_name)
arcpy.RefreshActiveView()
del mxd

Just specify attr_name variable.