On 2015-06-26 18:12, georgeryo...@gmail.com wrote:
[python 2.7, linux]
I have a python app. I cannot modify the file. But I can import it and mess
with it. I need to perform brief tasks before and after some of the member
functions.
I'd like to do this in as clear and maintainable way as possible (no third
party imports). Here's what I have now(which works):
from newvbr import * #get all the stuff from the newvbr app.
def perf_time(tag): # I do a little more than this, but you get the idea.
print >>sys.stderr, datetime.datetime.now().isoformat() + tag
def perf(tag):
def decorator(fn):
a def wrapper(*args):
perf_time('start %s' % tag)
ret = fn(*args)
perf_time('end %s' % tag)
return ret
return wrapper
return decorator
I use this on various members of various classes in the newvbr app:
old_database_snapshot = VerticaSession.database_snapshot
@perf('db_snap')
def new_database_snapshot(self, name):
old_database_snapshot(self, name)
VerticaSession.database_snapshot = new_database_snapshot
old_object_snapshot = VerticaSession.object_snapshot
@perf('obj_snap')
def new_object_snapshot(self, name):
old_object_snapshot(self, name)
VerticaSession.object_snapshot = new_object_snapshot
main() #do the usual stuff of the imported app, but with annotations.
This is still pretty laborious. How can I make something roughly like:
super_tagger(VerticaSession.database_snapshot)
that does all the above? I need to tag a bunch of function members like this.
I don't insist on using decorators, it just looked like that kind of problem.
You could do something like this:
def super_tagger(module, function_name, tag):
original_function = getattr(module, function_name)
@perf(tag)
def wrapper(*args, **kwargs):
return original_function(*args, **kwargs)
setattr(module, function_name, wrapper)
and then:
super_tagger(VerticaSession, 'database_snapshot', 'db'snap')
It might be cleaner to merge the functionality of 'perf' into it:
def super_tagger(module, function_name, tag):
original_function = getattr(module, function_name)
def wrapper(*args, **kwargs):
perf_time('start %s' % tag)
result = original_function(*args, **kwargs)
perf_time('end %s' % tag)
return result
setattr(module, function_name, wrapper)
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