topic Re: Why 'del mxd' in Python Questions

Why 'del mxd'

AnthonyFarndon — Thu, 12 May 2011 18:55:23 GMT

Hi

could anyone advise on the significance/requirement to delete the mxd variable after use, all example code ends with 'del mxd'?

I have some arcpy.mapping code wrapped up in a class, so wonder why, if at all, I need to do this. Should I call this in the class __del__ deconstructor perhaps, call del on the class/object itself after use or add in a custom deconstructor function after I have finished with the object to call del mxd on all the mxd's used in the class?

Thanks

Re: Why 'del mxd'

DanPatterson_Retired — Thu, 12 May 2011 19:14:14 GMT

It just deletes the reference to the *.mxd...called clean-up. Not necessary unless you are running many processes, but is generally good practice (think teenagers and their rooms ... clean-up is good)

Re: Why 'del mxd'

JakeSkinner — Thu, 12 May 2011 19:16:00 GMT

The 'mxd' variable will place a lock on the MXD. Without deleting this variable, the lock will remain.

For example, you run a python script that makes some change to an MXD and you don't delete the 'mxd' variable. Then you open this MXD in ArcMap, make another change and then try saving. You will receive an error that it is in use.

Re: Why 'del mxd'

AnthonyFarndon — Thu, 12 May 2011 20:17:47 GMT

thank you, makes sense now

Re: Why 'del mxd'

MikeMacRae — Thu, 09 Jun 2011 16:13:13 GMT

This also clears space in memory, which helps if your program is memory intensive.