tclpython

This package allows the execution of Python code from a Tcl interpreter, as in:

package require tclpython 3 set interpreter [python::interp new] $interpreter exec {print("Hello World")} puts [$interpreter eval 3/2.0] python::interp delete $interpreter

which outputs:

Hello World 1.5

It works by creating one or more embedded Python interpreters and sending them strings to evaluate or execute. Modules can be loaded in the Python interpreter as if it were the real Python program.

The commands created by the package are very simple:

• python::interp new
• python::interp delete interpreter
• interpreter eval script
• interpreter exec script

As expected, eval returns the Python interpreter result or reports an error at the Tcl level when the Python interpreter itself fails in executing the code string, while exec simply lets the Python interpreter execute the code and returns nothing or eventually report an error.

You can create several Python interpreters, if the tclpython package was linked against a Python library compiled with threads support, otherwise only 1 Python interpreter can exist at a time.

Notes:

• for Python 2.2 and above, the automatic import site on a new thread is suppressed because it otherwise makes the program hang (you can still use import site in your code, as described at the top of the Lib/site.py file).
• on a Redhat system, use the tclpython rpm on my homepage.
• tclpython is used by the moodss system monitoring software (information on my homepage) to allow its modules to be written in Python as well as Tcl and Perl.

Upgrading from tclpython version 2

In tclpython version 2, only the eval command was available to an interpreter. Some such invocations, generally that return nothing, need to be converted to the exec command, as the following examples show:

• $interpreter eval {print("Hello World")} ;# version 2 $interpreter exec {print("Hello World")} ;# version 3

• $interpreter eval {def initialize(): pass} ;# version 2 $interpreter exec {def initialize(): pass} ;# version 3

• # version 2: set exists [$interpreter eval "try: type(initialize) == FunctionType\nexcept: 0"] # version 3: $interpreter exec "try: result = (type(initialize) == FunctionType)\nexcept: result = 0" set exists [$interpreter eval result]

Send your comments, complaints, ... to jfontain@free.fr.
My homepage is at http://jfontain.free.fr/.