How to? return values from @python

[Stefano Piccardi]

What techniques are available to return values from %@python[] to TCC ?
I have been exploring some straightforward ways, but I can't see how to get something out of @python except for console output. Note that I am not using the supported ActivePython but another distribution, so my issue could be all there. Anyways, this is what I tried:

1. Capture standard output: set x=%@python[print 1+1] >out
   This sets x=0 (python's exit code?), creates an empty out file and prints 2 to the console.
2. Set a TCC variable from python: how can I do that?
   Incidentally I discovered that the persistent python interpreter gets its own frozen environment block, so setting environment variables, like $PATH, from python is pointless because changes aren't reflected in TCC's environment block.
3. Write to a file from python. Here is a working example, but I would like to find a memory based solution as well, like #2.

set tmpf=%@unique["%[TEMP]"]
echo>nul %@python[with open(r'%[tmpf]','w') as tmpf: print >>tmpf, 1+1]
type "%[tmpf]"
del "%[tmpf]"

 

[Steve Pitts]

I can't speak for the Python support Stefano, but the equivalent @REXX simply allows you to return a numeric value valid as an exit code (REXX has both EXIT and RETURN 'statements' that can be used to achieve that). Any attempt to return a value that cannot be interpreted as a number (and this might differ for python, REXX has no data typing so all data are effectively strings) causes the TCC instance to crash.

 

[Stefano Piccardi]

Thanks Steve. I read in an older thread of this forum that performing an exit(n) in python closes the TCC session as well because the python interpreter is persistent.

 

[jpavel]

Just to resurrect this old thread, I found that at least with TCC v25, one can successfully set environment variables in Python and read them in the same TCC session:

> set r=%@python[from os import environ as env]
> set r=%@python[env['pyfoo'] = str(2**16)]
> echo %pyfoo
65536

 

[jpavel]

With this function, I've made Python very easy to integrate into my TCC scripts:

:: User-defined variable function
PyEval=%@IF[%@python["import os; os.environ['PyEval_Output'] = str(%$)"] == 0,%PyEval_Output,]

And so one can do things like

> set nums=%@PyEval["-".join(str(i) for i in range(1,11))]
> echo %nums
1-2-3-4-5-6-7-8-9-10

Jesse