How to Call TCL Procedure using Python

Question

Using below code i can able to call all procedure in the Proc.tcl file ,but i want to call individually the procs like sum or sub ,Please let me know any other possibility to call it

My proc file program,

 puts "hello"
    proc sum {a b} {

     set c [expr $a + $b]
     puts "Addition: $c "
    }




  proc sub {a b} {

     set c [expr $a - $b]
     puts "Substraction: $c "
    }

My Main file program,

 import Tkinter
    import os
    r=Tkinter.Tk()
    r.tk.eval('source proc.tcl')

Answer 1

Just carry on as you are:

>>> import Tkinter
>>> r = Tkinter.Tk()
>>> r.tk.eval('proc sum {a b} {set c [expr {$a + $b}]; puts "Sum $c"; return $c}')
''
>>> r.tk.eval('sum 2 5')
Sum 7
'7'

So in your case, having sourced the tcl file you can just do r.tk.eval("sum 5 5") to call that procedure.

Note: always brace expr expressions in tcl. As in my example above.

Answer 2

I do not know tcl, but this looks logical:

import tkinter
r=tkinter.Tk()
r.tk.eval('source proc.tcl')
r.tk.eval('sum 1 2')
r.tk.eval('sub 1 2')

>>> hello
>>> Addition: 3 
>>> Substraction: -1

Answer 3

If you don't need the power of Tkinter, you can restructure proc.tcl a little and call the proc via subprocess:

proc.tcl:

proc sum {a b} {
    set c [expr $a + $b]
    puts "Addition: $c "
}

proc sub {a b} {
    set c [expr $a - $b]
    puts "Substraction: $c "
}

eval $argv; # NOTE 1

caller.py:

import subprocess
import shlex

def tcl(command):
    command_line = shlex.split(command)
    output = subprocess.check_output(command_line)
    return output

print tcl('tclsh proc.tcl sum 5 8')
print tcl('tclsh proc.tcl sub 19 8')

Output of caller.py:

Addition: 13

Substraction: 11

Discussion

• Note 1: In the Tcl script, the line eval $argv takes what on the command line and execute it. It does not provide error checking at all, so potentially is dangerous. You will want to check the command line for malicious intention before executing it. What I have here is good for demonstration purpose.

• The function tcl in caller.py takes a command line, split it, and call proc.tcl to do the work. It collects the output and return it to the caller. Again, for demonstration purpose, I did not include any error checking at all.