Re-using TCL code from python over network

[Karim]

On 29/03/2016 07:20, sharad1087 at gmail.com wrote:
> Hi
>
> We've a test automation framework written in TCL (including the automated test cases). We are evaluating shifting to Python and have a test framework in Python (including the automated test cases). Python provides a lot more 3rd party libraries that we'd like to make use of.
>
> We use a pretty old version of TCL (8.4.5, 32 bit). It's on FreeBSD and we've compiled it in-house. Compiling it to 64 bit or moving to a newer version is a massive task (since we've a lot of libraries - written in C and compiled as well as pure tcl).
>
> Also, we are evaluating having this Python infrastructure on Linux (CentOS).
>
> I've explored Python's Tkinter but it won't suit our case as it points to system installed TCL. I've also explored Python's subprocess (launch an interactive TCL shell remotely) and pexpect but none of them worked well for me to allow me to use TCL code interactively from Python.
>
> I'd like to gather any ideas/experience around this. If anyone has tried a similar stuff before and can share his/her experience, I'd appreciate it.
>
> Regards
> Sharad

You can find below a partial example where I launch a python process 
from a tcl program to get data from python
which reads a database. You just have to get and compile tclpython 
(google is your best friend) which is a C interface
bridging python and tcl and allow to launch at most 5 python interpreter 
processes if I remember correctly. I used it during 4
years but I now I migrated all the TCL code to python one indeed I don't 
need it anymore. But it is useful to do the transition.

#!/usr/bin/env tclsh8.4

lappend auto_path $env(TCLPYTHON_PKG_PATH)
package require tclpython 4.1

namespace eval ops {
   namespace export initPython
   namespace export exitPython
...
   namespace export getDeviceDescription

....
}

proc ops::initPython {} {
# ----------------------------
# @goal: Create the interpreter process and import python needed modules.
# @arg:  <none>
# @return: <none>
# ----------------------------
   variable interpreter
   set interpreter [python::interp new]
   $interpreter exec {from ops.tcl.pythontcl         import to_string, 
to_list, to_dict, to_bool}
   ....
   $interpreter exec "opsdb = None"
   $interpreter exec "input_structure = dict()"
}

proc ops::exitPython {} {
# ----------------------------
# @goal: Close the interpreter process.
# @arg:  <none>
# @return: <none>
# ----------------------------
   variable interpreter
   python::interp delete $interpreter
}

proc ops::getDeviceDescription { libName deviceName } {
# ----------------------------
# @goal: get
# @arg:  <none>
# @return:
# ----------------------------
   variable interpreter
   $interpreter exec "d_s = to_string(getDeviceDescription(opsdb, 
'$libName', '$deviceName'))"

   eval "set value [$interpreter eval {d_s}]"
   return $value
}

Karim