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copied!<p>This is really just a matter of convention, exception handling in python is designed to be used heavily (beg forgiveness rather than ask permission). And given that you're working in a different language space, you want to follow those conventions - ie/ you really do want to let developers know where the site of the exception was. But if your really do need to do this ...</p> <p><strong>Using the Inspect Module</strong></p> <p>The <a href="http://docs.python.org/library/inspect.html" rel="nofollow noreferrer">inspect module</a> will do pretty much everything you need to reconstruct a nice version of carp, that works without having to worry about decorators (see below). As per the <a href="https://stackoverflow.com/questions/1095543/get-name-of-calling-functions-module-in-python">comments in this answer</a>, it may be that this approach will break on pythons other than cpython </p> <pre><code># revised carp.py import sys import inspect def carp( msg ): # grab the current call stack, and remove the stuff we don't want stack = inspect.stack() stack = stack[1:] caller_func = stack[0][1] caller_line = stack[0][2] sys.stderr.write('%s at %s line %d\n' % (msg, caller_func, caller_line)) for idx, frame in enumerate(stack[1:]): # The frame, one up from `frame` upframe = stack[idx] upframe_record = upframe[0] upframe_func = upframe[3] upframe_module = inspect.getmodule(upframe_record).__name__ # The stuff we need from the current frame frame_file = frame[1] frame_line = frame[2] sys.stderr.write( '\t%s.%s ' % (upframe_module, upframe_func) ) sys.stderr.write( 'called at %s line %d\n' % (frame_file, frame_line) ) # Exit, circumventing (most) exception handling sys.exit(1) </code></pre> <p>Which for the following example:</p> <pre><code> 1 import carp 2 3 def f(): 4 carp.carp( 'carpmsg' ) 5 6 def g(): 7 f() 8 9 g() </code></pre> <p>Produces the output:</p> <pre><code>msg at main.py line 4 __main__.f called at main.py line 7 __main__.g called at main.py line 9 </code></pre> <p><strong>Using Traceback</strong></p> <p><em>This was the original approach proposed.</em></p> <p>An equivalent to carp could also be written in python by manipulating traceback objects, see the documentation in the <a href="http://docs.python.org/library/traceback.html" rel="nofollow noreferrer">traceback module</a>. The main challenge in doing this turns out to be injecting the exception and traceback print code. It is worth noting that the code in this section is very fragile.</p> <pre><code># carp.py import sys import traceback ''' carp.py - partial emulation of the concept of perls Carp::carp ''' class CarpError(Exception): def __init__(self, value): self.value = value def __str__(self): return repr(self.value) def carpmain( fun ): def impl(): try: fun() except CarpError as ex: _, _, tb = sys.exc_info() items = traceback.extract_tb(tb)[:-1] filename, lineno, funcname, line = items[-1] print '%s at %s line %d' % (ex.value, filename, lineno) for item in items[1:]: filename, lineno, funcname, line = item print '\t%s called at %s line %d' % (funcname, filename, lineno) return impl def carp( value ): raise CarpError( value ) </code></pre> <p>Which can be called using the following basic process:</p> <pre><code>import carp def g(): carp.carp( 'pmsg' ) def f(): g() @carp.carpmain def main(): f() main() </code></pre> <p>The output of which is:</p> <pre><code>msg at foo.py line 4 main called at foo.py line 12 f called at foo.py line 7 g called at foo.py line 4 </code></pre> <p><strong>Perl Reference Example</strong></p> <p>For completeness, both solutions proposed in this answer were debugged by comparing results to this equivalent perl example:</p> <pre><code> 1 use strict; 2 use warnings; 3 use Carp; 4 5 sub f { 6 Carp::carp("msg"); 7 } 8 9 sub g { 10 f(); 11 } 12 13 g(); </code></pre> <p>Which has the output:</p> <pre><code>msg at foo.pl line 6 main::f() called at foo.pl line 10 main::g() called at foo.pl line 13 </code></pre>

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