Python

Python is an open-source scripting and general programming language, often used for rapid application development.

Attributes

current versions

contact: g u i d o at C N R I dot R e s t o n dot V A dot U S (Guido van Rossum)

contact: f r e d r i k dot l u n d h at i m a g e dot c o m b i t e c h dot s e (Fredrik Lundh)

Tools

critlib's Typcl: an extension to use Tcl *from* Python. It doesn't really require CriTcl and could have been done in standard C.

Elmer: Elmer allows developers to write code in Python and execute it in Tcl. The resulting Tcl interface to the Python code generated by Elmer is transparent to the Tcl user... Python calls appear as Tcl calls ( "foo( 1, "a" )" in Python appears as "foo 1 a" in Tcl, for example) and Python and Tcl data types are automatically mapped (Tcl lists are converted to Python lists, Python dictionaries are returned as Tcl associative arrays, etc.). Elmer also supports Python's "freeze" module, allowing a Python developer to deliver a single library consisting of several Python files "frozen" in to the Tcl application... no need to set PYTHONPATH or have Python source files accompanying the Tcl application.

libtclpy: a Tcl extension to call Python from inside Tcl. The intention is to take the good parts of Elmer and tclpython and combine them to let you get going as fast as possible.

Description

Python includes a standard facility for object-oriented programming.

Tcl is bundled into Python in order to make Tk available as the Python module, Tkinter. Beginning at version v1.5.2, includes IDLE, an integrated development environment for Python that requires Tkinter. Python 2.4 not only supports Tk on Unix, but Tk on Windows and Macintosh platforms as well.

An example of converting a Tcl list to a Python tuple:

#! /bin/env python

import Tkinter
tcl = Tkinter.Tcl()
result = tcl.call('lrange' ,'''one {two and} three''' ,0 ,'end')

To evaluate a Tcl script:

#! /bin/env python

import Tkinter
tcl = Tkinter.Tcl()
result = tcl.eval('some Tcl script here')

ActiveState provides Active Python binary downloads for Linux, Solaris and Windows.

Python, Enthought Edition , now Enthought Canopy , provides Python+packages bundle.

Misc

AMG: Does anyone have Tcl code to read Python pickle [L2 ] data? Tcl pickle, heh. Maybe someday I might develop it, if no one else has already done so.

"a Python script can be expected to work for two to three years, but not for five or more. Older scripts will either crash, which is a nuisance, or produce different results, which is much worse because the problem may well go unnoticed." [L3 ]

The Art of dividing two numbers in Python:

% Python 2.7
>>> 5 / 2
2

% Python 3.x
>>> 5 / 2
2.5

% Python 2.7
>>> from __future__ import division
...
>>> 5 / 2
2.5

% Python 2.7/3.x
>>> 5 // 2
2
>>> 1 / 0.2
5
>>> 1 // 0.2
4

arjen - 2019-08-30 07:43:20

What exactly is the difference between / and // in Python? I could imagine what is going on in the first few examples, but "1//0.2" resulting in "4" really makes me wonder ...

In theory (see PEP 238 ) the operator // realizes a flooring division and a // b could be equivalent to math.floor(a / b). But it seems there are hairy corners behind the scenes and this is not equivalent (Python 3.4.1):

>>> import math
>>> math.floor(1 / 0.2)
5
>>> 1 // 0.2
4
>>> math.floor(44 / 4.4)
10
>>> 44 // 4.4
9.0

However after the division operator was "improved" people seem to have great fun to figure out how division actually behaves for their packages and Python version. Tcl...

% expr 5 / 2
2
% expr 5 / 2.0
2.5
% expr 1 / 0.2
5.0
% expr floor(1 / 0.2)
5.0

another example divison in python

"Any language that can’t process valid filenames has serious bugs – and Python is littered with these bugs."

"At this point, I am extremely unlikely to use Python for any new project due to these issues."

-- The Incredible Disaster of Python 3

"Python is not a great programming language. It's great for beginners. Then it turns into a mess." [L4 ]

Category Language

Category Object Orientation

Python

Attributes

See Also

Tools

Description

Misc