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Python package management.

Charles Sasaki-Skopp11-18-2021 20:22

Is there a best practice way to version python packages between production and testing UniData accounts ...

Mike Rajkowski11-19-2021 13:44

Dealing with the Python Path The Question comes up from time to time on how can a U2 developer have ...

1. Python package management.

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Charles Sasaki-Skopp
Posted 11-18-2021 20:22

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Is there a best practice way to version python packages between production and testing UniData accounts on the same server? The .pth files load in the same order regardless of which account a user is in (which makes sense), and relative paths + environmental variables don't seem to be supported in .pth. Was hoping to be able to make and test changes to a package in a directory under the testing account and move to the production account only when ready, possibly updating a production package. Separate servers, while desirable, in not possible right now.

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Charles Sasaki-Skopp
IT Coordinator/Developer
VSI
Albany OR US
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2. RE: Python package management.

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Mike Rajkowski
Posted 11-19-2021 13:44
Edited by Mike Rajkowski 11-19-2021 13:58

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Dealing with the Python Path

The Question comes up from time to time on how can a U2 developer have multiple versions of a Python module on the same system.

IMHO: This is not a good idea and should be avoided

There are a lot of situations where you can run into issues with this type of Python implementation, and I would recommend having a different system for development, and not doing anything on the production server.

How Python determine what is version of a package/module is imported

Python has its own path variable, and uses it to determine where it looks when you import a package.

In [1]:

import pprint import sys pprint.pprint(sys.path)

['C:\\U2\\ud82\\XDEMO\\JUPYTER', 'c:\\u2\\ud82\\python\\python39.zip', 'c:\\u2\\ud82\\python\\DLLs', 'c:\\u2\\ud82\\python\\lib', 'c:\\u2\\ud82\\python', '', 'C:\\Users\\mrajkowski\\AppData\\Roaming\\Python\\Python39\\site-packages', 'C:\\Users\\mrajkowski\\AppData\\Roaming\\Python\\Python39\\site-packages\\win32', 'C:\\Users\\mrajkowski\\AppData\\Roaming\\Python\\Python39\\site-packages\\win32\\lib', 'C:\\Users\\mrajkowski\\AppData\\Roaming\\Python\\Python39\\site-packages\\Pythonwin', 'C:\\U2\\ud82\\bin', 'C:\\U2\\ud82\\XDEMO\\PP', 'c:\\u2\\ud82\\python\\lib\\site-packages', 'C:\\Users\\mrajkowski\\AppData\\Roaming\\Python\\Python39\\site-packages\\IPython\\extensions', 'C:\\Users\\mrajkowski\\.ipython']

Note that in the above you see the C:\U2\ud82\bin and C:\U2\ud82\XDEMO\PP these are from my u2.pth file that is in my UDTHOME account.

If a package/module is in multiple locations, the first one found would be used. So, if something I wanted was in the current directory as well as being in C:\U2\ud82\XDEMO\PP, the version in the current directory would be loaded since it was found first.

It is possible to modify the sys.path

In [2]:

sys.path.remove('C:\\U2\\ud82\\XDEMO\\PP') sys.path.insert(0, 'C:\\U2\\ud82\\XDEMO\\PP') pprint.pprint(sys.path)

['C:\\U2\\ud82\\XDEMO\\PP', 'C:\\U2\\ud82\\XDEMO\\JUPYTER', 'c:\\u2\\ud82\\python\\python39.zip', 'c:\\u2\\ud82\\python\\DLLs', 'c:\\u2\\ud82\\python\\lib', 'c:\\u2\\ud82\\python', '', 'C:\\Users\\mrajkowski\\AppData\\Roaming\\Python\\Python39\\site-packages', 'C:\\Users\\mrajkowski\\AppData\\Roaming\\Python\\Python39\\site-packages\\win32', 'C:\\Users\\mrajkowski\\AppData\\Roaming\\Python\\Python39\\site-packages\\win32\\lib', 'C:\\Users\\mrajkowski\\AppData\\Roaming\\Python\\Python39\\site-packages\\Pythonwin', 'C:\\U2\\ud82\\bin', 'c:\\u2\\ud82\\python\\lib\\site-packages', 'C:\\Users\\mrajkowski\\AppData\\Roaming\\Python\\Python39\\site-packages\\IPython\\extensions', 'C:\\Users\\mrajkowski\\.ipython']

Note that while this seems like it may do what you want, you run the risk of having issues once you have loaded a package/module.

In [4]:

print("first time you import, the code is executed") import Greeting print("if you import something that was previously imported it does not re-import") import Greeting

first time you import, the code is executed Type your name: mike Hello mike if you import something that was previously imported it does not re-import

This can cause confusion on wether or not your changes are being used. The best practice is to stop the running Python process and start a new one.

How to reload a Python module

Yet, if you are on a test box at the REPL prompt, you might want to reload the module. Look at using the importlib module to help you with this.

In [5]:

import importlib reloaded = importlib.reload(Greeting) print() # as an added bonus, the reload function returns the path to what was importd print("Reloaded: " + str(reloaded)) # you can also see the by looking at the __file__ property of the module object print("Greeting.__file__ = " + Greeting.__file__)

Type your name: mike Hello mike Reloaded: <module 'Greeting' from 'C:\\U2\\ud82\\XDEMO\\PP\\Greeting.py'> Greeting.__file__ = C:\U2\ud82\XDEMO\PP\Greeting.py

Looking at the path of the module is a good way to determine what you just imported.

Note there are also ways to unload modules so you can reload them, but once again, I do not recommend doing this since you run the risk of loading the wrong module and/or pointing to the wrong data.

IMHO: This is not a good idea and should be avoided

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Mike Rajkowski
support
Rocket Internal - All Brands
DENVER CO US
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Original Message

Rocket U2 | UniVerse & UniData

Python package management.

Charles Sasaki-Skopp11-18-2021 20:22

Mike Rajkowski11-19-2021 13:44

1. Python package management.

2. RE: Python package management.

Dealing with the Python Path

IMHO: This is not a good idea and should be avoided

How Python determine what is version of a package/module is imported

It is possible to modify the sys.path

How to reload a Python module

Note there are also ways to unload modules so you can reload them, but once again, I do not recommend doing this since you run the risk of loading the wrong module and/or pointing to the wrong data.

IMHO: This is not a good idea and should be avoided

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