Debug Python code

Python Print

In a Python ran externally it is opened a DOS console, and then it is possible to use the Python function print to show values in this console

But running code inside GiD this console doesn’t exists, and then this command cannot be used, except in case that the IDLE shell is opened and then the output of print is showed there.

Python print to file

To debug Python code it is always possible (inside and outside GiD) to print data of variables to a file, with something like this:

f=open('C:/temp/my_debug.txt','a')
f.write('hello world\n')
f.close()

Python show text with the W GiD proc

If Python is running in GiD then can call the Tcl GiD procedure called W that show text in a window

e.g.

GiD_Python_Exec {
  import tohil
  tcl=tohil.import_tcl()
  a=5.2
  tcl.W(a)
  b=a*3
  tcl.W(b)
}

will show a GiD window with the value of the variables 'a' and 'b'

Note: tcl = tohil.import_tcl() is a tohil module command that uses Tcl’s introspection capabilities to create Python object methods for each Tcl proc and command, so that calling the Tcl procs looks very much like calling any Python function.

Warning: the Python methods created depends on the procs existing when tohil.import_tcl() is invoked. If a proc like W is already not defined in Tcl during this call, the Python method tcl.W('hello world') won’t exists, but tohil.call('W','hello world') will works.

Warning: It seems that tcl.W() cannot be called from the IDLE shell window or will crash

By now do not try something like this or GiD will crash:

In this case it is less interesting to be used, because can use print(). The most interesting case is to use to debug code of GiD_Python_Exec, or GiD_Python_Source