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Python one-liner to get the filename and line number of the caller of the current function

By Vasudev Ram

Just saw this:

An ActiveState Python recipe to get the filename and line number of the calling function.

I modified it and tried it out, while I happened to be at an Internet cafe, using Portable Python, which I had blogged about earlier.

Here is my modified code:

# caller_info.py

import sys

def foo():
 print "in foo"
 f1 = sys._getframe(1)
 f2 = sys._getframe(2)
 print "f1: filename, lineno:", f1.f_code.co_filename, f1.f_lineno
 print "f2: filename, lineno:", f2.f_code.co_filename, f2.f_lineno

def bar():
 print "in bar"
 print "calling foo"
 foo()

bar()

And here is the output of "running" (*) that file, caller_info.py, using Portable Python:

>>> import caller_info
in bar
calling foo
in foo
f1: filename, lineno: caller_info.py 16
f2: filename, lineno: caller_info.py 18
>>>

(*) I said "running" because, as you can see from the code, I had to use a roundabout method of running the caller_info.py file with PortablePython. The standard method, like "python caller_info.py", that normal Python supports, does not seem to work with PortablePython (at least on a quick check or two; there may be some other way that works, such as a command-line switch or whatever). So I resorted to importing the file and letting the code in it run as a side-effect. Anyway, it seems to show that the one-liner works, because in the output shown, the filename is right, and so are the line numbers of the calls to foo and bar - I checked in the editor that the numbers are 16 and 18.

Just for fun, I also tried the same code (not as a Python file, just typed in), in the
repl.it online pastebin that I blogged about earlier. It worked, sort of, the line number shown was 1 and the filename shown was stdin:

def foo(): 
..   print "in foo" 
..
 def bar(): 
..   print "in bar, calling foo" 
..   foo() 
..   f = sys._getframe(1) 
..   print f.f_code.co_filename 
..   print f.f_lineno 
..   
   bar()
in bar, calling foo
in foo
<stdin>
1

- Vasudev Ram - Dancing Bison Enterprises

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Portable Python, Python on a USB stick

Portable Python is a Python installation preconfigured to run from any USB storage device, like a USB stick.

You only have to download and extract it and then you can starting using Python to develop applications.

It is available for some versions of Python 2 and Python 3. It also comes with many other Python packages / tools. It is optional to install those during the Portable Python installation. Some of those packages are:

PyScripter v2.5.3
NymPy 1.6.2 (*)
SciPy 0.11.0
Matplotlib 1.1.1
PyWin32 218
Django 1.4.3
PIL 1.1.7
Py2Exe 0.6.9
wxPython 2.9.4.0
NetworkX 1.7
Lxml 2.3
PySerial 2.5
PyODBC 3.0.6
PyGame 1.9.1
PyGTK 2.24.2
PyQt 4.9.6-1

(*) Nympy is probably a typo, it must be Numpy.

The fact that it includes Django, wxPython, PyGTK, PyQt, SciPy, Matplotlib, etc., makes it more useful out of the box.

I am trying out Portable Python and will report on my experience with it after a while. If it works well I think it could be a useful tool for people who sometimes need to program with Python on the go, at any place where they may not have a regular installation of Python available, e.g. if you are somewhere without a desktop PC or a laptop, maybe at an Internet cafe, it could be useful there.

The Portable Python About page gives some info about its background and goals.

Vasudev Ram - Dancing Bison Enterprises