Ian Hobson a écrit :
Hi all you experts,
This has me beat. Has anyone any ideas about what might be going wrong?
This is code from within a windows service (hence no print statements -
no sys.stdout to print on!).
I am trying to trace through to find where the code is not working. No
stdout so I have to log to a file.
Then you'd be better using the logging module from the stdlib. And FWIW,
you should try to make you code testable in a non-service context...
I have the following code fragments.
def log(message):
f = open('d:\logfile.txt','a')
f.write(message + "\n")
f.close()
from DelNotePrinter import DelNotePrinter
<OT>
The convention is to use all_lower_names for modules - having modules
and classes with the same (case-sensitive) name can be very misleading.
</OT>
note the order of the above - log is defined before the import.
And ? Do you think it will affect the imported module in any way ? Like,
say, magically "inject" your log function in the DelNotePrinter module ?-)
Later in the source
Where ?
I have
log('disPrint is:'+disPrint)
log('count is:'+count)
Do yourself a favor and learn string formating...
log(repr(DelNotePrinter))
printer = DelNotePrinter(disPrint,int(count))
The DelNotePrinter.py file cannot us log even though it is declared
as global.
In Python, "global" means "module-level", and it's only necessary when
you want to rebind a module-level name from within a function or method.
The code is...
# coding=utf8
# DelNotePrinter = code to print delivery notes
assorted imports removed for space reasons
Some of these imports surely explain why you don't just get a NameError
when trying to call log() - wild guess : you have some "from xxx import
*" statement that does import another callable named 'log'.
class DelNotePrinter(object):
''' Print Delivery Note on A5 in portrait '''
def __init__(self,printer,copies):
''' create printer and painter '''
global font,sm,log
log('DelNotePrinter: starting')
self.printer = QPrinter(QPrinter.HighResolution)
If you want to access a name (function, class, whatever) defined in
another module, you have to explicitely import it.
The file the log writes contains..
disPrint is:HP Deskjet 6940 series
count is:1
<class 'DelNotePrinter.DelNotePrinter'>
The > is followed by a newline and end of file! Where is the
DelNotePrinter: starting message?
We can't tell - but you can get at least some hint, cf below
If I replace the opening of __init__ with
global font,sm,log
f = open('d:\logfile.txt','a')
f.write('DelNotePrinter: starting' + "\n")
f.close()
self.printer = QPrinter(QPrinter.HighResolution)
then the message IS written to the log file.
Obviously, yes. Now please add this to your code:
class DelNotePrinter(object):
''' Print Delivery Note on A5 in portrait '''
def __init__(self,printer,copies):
''' create printer and painter '''
global font,sm,log
f = open('d:\logfile.txt','a')
f.write('DelNotePrinter: starting' + "\n")
# check what "log" is bound to in the currrent namespace
f.write(
"DelNotePrinter : log is '%s' from '%s'" % (
log, log.__module__
))
f.close()
self.printer = QPrinter(QPrinter.HighResolution)
I have read http://docs.python.org/reference/simple_stmts.html#global
very carefully and I still don't understand.
The statement definition makes no sense if you don't understand
namespaces and bindings:
http://docs.python.org/reference/executionmodel.html#naming-and-binding
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