Question

Is there a similar mechanism in Python, to the effect set -x has on bash?

Here’s some example output from bash in this mode:

+ for src in cpfs.c log.c popcnt.c ssse3_popcount.c blkcache.c context.c types.c device.c
++ my_mktemp blkcache.c.o
+++ mktemp -t blkcache.c.o.2160.XXX
++ p=/tmp/blkcache.c.o.2160.IKA
++ test 0 -eq 0
++ echo /tmp/blkcache.c.o.2160.IKA
+ obj=/tmp/blkcache.c.o.2160.IKA

I’m aware of the Python trace module, however its output seems to be extremely verbose, and not high level like that of bash.

Answer 1

Perhaps use sys.settrace:

Use traceit() to turn on tracing, use traceit(False) to turn off tracing.

import sys
import linecache

def _traceit(frame, event, arg):
    '''
    http://www.dalkescientific.com/writings/diary/archive/2005/04/20/tracing_python_code.html
    '''
    if event == "line":
        lineno = frame.f_lineno
        filename = frame.f_globals["__file__"]
        if (filename.endswith(".pyc") or
            filename.endswith(".pyo")):
            filename = filename[:-1]
        name = frame.f_globals["__name__"]
        line = linecache.getline(filename, lineno)
        print "%s  # %s:%s" % (line.rstrip(), name, lineno,)
    return _traceit

def _passit(frame, event, arg):
    return _passit

def traceit(on=True):
    if on: sys.settrace(_traceit)
    else: sys.settrace(_passit)

def mktemp(src):
    pass

def my_mktemp(src):
    mktemp(src)
    p=src

traceit()
for src in ('cpfs.c','log.c',):
    my_mktemp(src)
traceit(False)

yields

mktemp(src)  # __main__:33
pass  # __main__:30
p=src  # __main__:34
mktemp(src)  # __main__:33
pass  # __main__:30
p=src  # __main__:34
if on: sys.settrace(_traceit)  # __main__:26
else: sys.settrace(_passit)  # __main__:27