Geoprocessing Tool prevents printing in Python

Question

When using geoprocessing tools in a Python (2.5) script it appears to be preventing the script from outputting any further "print" command text to the screen. I am using various gp tools and they all appear to exhibit the same behavior. I use python "write" commands to write script processing progress into a text log, which is still working correctly. An example would be where I'm using the gp.FeatureClassToShapefile_conversion tool to export shapefiles from a geodatabase to a folder. If I comment out the gp tool the While loop proceeds perfectly and will print to the screen and write to the log. Here is a snippet of the code (it is properly indented, but won't display properly in this post):

# Sample Variables
New_Geo_GDB = "\\c:\test\ blahblah.gdb

try:
 print "Start exporting shapefiles from feature classes of " + New_Geo_GDB + " " + time.strftime("%H:%M:%S", time.localtime())
 writeLog.write('Start exporting shapefiles from feature classes of ' + New_Geo_GDB + ' ' + time.strftime("%H:%M:%S", time.localtime()) + ' 
')
 # SET WORKSPACE TO THE GEODATABASE
 gp.Workspace = New_Geo_GDB
 # CREATE OBJECT TO HOLD GEODATABASE OBJECTS
 desc = gp.Describe(New_Geo_GDB)
 # CREATE CHILDREN VARIABLE TO HOLD LIST OF FEATURE CLASS NAMES
 children = desc.Children
 # RESET THE LIST TO THE BEGINNING
 children.Reset()
 # MOVE TO THE FIRST OBJECT IN THE LIST
 child = children.Next()
 # LOOP THORUGH THE CHILD OBJECTS WHILE THEY EXIST
 while child:
  # CREATE VARIABLE TO STORE THE GEODATABASE AND THE FEATURE CLASS NAME TO EXPORT
  InGeo_Dataset = New_Geo_GDB + "\" + child.Name
  # PRINT AND WRITE TO THE LOG
  print "Exporting to shapefile folder: " + child.Name 
  writeLog.write('Exporting to shapefile folder: ' + child.Name + ' 
')
  # GEOPROCESSING OBJECT TO EXPORT FEATURE CLASS TO SHAPEFILE
  gp.FeatureClassToShapefile_conversion(InGeo_Dataset, shapeDir)
               # MOVE TO THE NEXT FEATURE CLASS
  child = children.Next()
 print "Finished exporting feature classes to shapefiles: " + time.strftime("%H:%M:%S", time.localtime())
 print " "
 writeLog.write('Finished exporting feature classes to shapefiles: ' + time.strftime("%H:%M:%S", time.localtime()) + ' 
')
 writeLog.write('  
')
except:
 print "! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! "
 print "Export shapefiles failed!"
 print gp.GetMessages(2)
 writeLog.write('! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !  
')
 writeLog.write('Export shapefiles failed! 
')
 writeLog.write(gp.GetMessages(2) + ' 
')

JasonScheirer · Answer

I second the use of the Python logging module for any large/long-running tool. It's fairly trivial to add logging handlers that post to gp.addMessage and gp.addError when the severity level of a logging message is high enough, and you can log less important messages to log files for later inspection, etc.

FrankPerks · Answer

Hi,

You can overload the sys streams after esri plays with them, to restore print functionality. So you can have a happy print.
import arcgisscripting
import sys

class GPPrint(object):
    """
        Use enable or disable print please =)
    """
    def __init__(self, gp, is_stderr = False):
        """
            Initializer
        """
        self.gp = gp
        self.is_stderr = is_stderr

def __del__(self):
        self.gp = None

def write(self, msg):
        if msg == '
':
            return
        if self.gp:
            if not self.is_stderr:
                self.gp.addmessage(msg)
            else:
                self.gp.adderror(msg)

def flush(self):
        pass

def writelines(self, msg):
        self.write('
'.join(msg))

def close(self):
        pass

gp = arcgisscripting.create()
sys.stderr = GPPrint(gp, True)
sys.stdout = GPPrint(gp, False)

print "Hi"
print "Hello normally this would not work but i am =) "

# Now lets say we want to restore the streams...

sys.stderr = sys.__stderr__
sys.stdout = sys.__stdout__

However i strongly suggest you look into the logging module for working with large projects.

JoeHeggenstaller · Answer

I noticed that also, but was trying to keep my example simple. Thanks.