[Tutor] Getting caller name without the help of "sys._getframe(1).f_code.co_name" ?

[patrice laporte]

2010/2/13 Luke Paireepinart <rabidpoobear at gmail.com>

>
>
> On Sat, Feb 13, 2010 at 9:56 AM, patrice laporte <zepangolin at gmail.com>wrote:
>
>>
>> Hi,
>>
>> Being in an exeption of my own, I want to print the name of the caller,
>> and I'm looking for a way to have it.
>>
>> Could you tell us exactly why you want to do this?  It seems sort of
> strange.  Also couldn't you pass the caller as an argument to your function?
>
>
Hi,

I don't know if it's strange, maybe, so tell me why. Or maybe it's me....
Maybe the fact I'm à pure C coder for a longtime prevent me from thinking in
Python, maybe my brain is only capable of thinking and viewing in C..... and
maybe there's an obvious way to solve my problem that I can't see yet... or
maybe it's because I'm French, genetically programed to live in the past ?
... so this mailing list is my starting point to improve my Python
understanding.

And now, something different : what I want to do, and why.

I got a class that takes a file name in its  __init__ method (it could be
elsewhere, but why not here ?). Then, somewhere in that class, a method will
do something with that file  name, such as "try to open that file".

If the file do esn't exist, bing ! I got an exception "I/O Error n°2 : file
doesn't exist".

That's nice, I of course catch this exception, but it's not enough for the
user : What file are we talking about ?  And how to tell the user  what is
that file, and make him understand  he tell the app to use a file that
doesn't exist ?
And this is not enough for developer : where that error happened ? what
class ? what method ?

There is many solution, and mine is :

- don't check for the existence of the file in __init__
- don't use a default value for the file name parameter in __init__ : coder
MUST provide it.
- try/catch open(this_file_name) and if I got an IOErro exception, I
re-raise my own exception with :
   - the name of the class where that IOError occured
   - the name of the method in that class that make that error occured
   - the name of the file the method tried to opened
   - some other info to help diagnostic

Then my exception object can :
   - log in a file dedicated to the team (so, just me for the moment)
   - and/or log in a file dedicated to the user

And then the app can popup a message box or something like that.

Currently, I'm thinking about "how to get that class/method name", easily,
and make something usefull with that.

I don't want to write the name of the method and the class each time I need
to use my exception class, and I don't want to modify that name each time
I'm doing a refactoring operation : I just want to do something like :

   except IOError, (errno, errmes):
            raise myexceptioniwanttobenice ("IO Error %d -> %s ('%s')" %
(errno, errmes, self.__csv) )

And then I print somewhere a message like :

          Error in csv2db.getColumnFromCsv : IO Error 2 -> No such file or
directory ('toto')

What I don't want is to write something like :

except IOError, (errno, errmes):
            raise myexceptioniwanttobenice ("cvs2db.getColumnFromCsv IO
Error %d -> %s ('%s')" % (errno, errmes, self.__csv) )

I don't want because it's to much to write, and if I change the class name,
I don't want to rewrite all my call to change that name.

So, I was looking for a way to retrieve :
The name of the class the object that throw the exception belongs to
The name of the method in that class

And I finally found those recipe with the sys._getframe call.

My first solution, currently, is (I didn't yet rewrite it with the solution
with the traceback module) :

class argError(Exception):
    def __init__(self, callerClass, errorMessage):
        self.__class   = callerClass.__class__.__name__
        self.__method  = sys._getframe(1).f_code.co_name
        self.__message = errorMessage

    def __str__(self):
        return "Error in %s.%s : %s" % (self.__class, self.__method,
self.__message)

And how I use it :

       try:
            f = open(self.__csv)
        except IOError, (errno, errmes):
            raise argError (self, "IO Error %d -> %s ('%s')" % (errno,
errmes, self.__csv) )

I now will :
- rewrite it with the solution with traceback module
- read about that module and find how to get rid of the need to pass "self"
as an argument in the call "raise argError (*self*, "IO Error %d -> %s
('%s')" % (errno, errmes, self.__csv) )". That call enable me to get the
name of the class.

All of that is a way to me to experiment Python, I try a lot of thing to
understand, and then I will make a choice.

But now, it's time to lunch. Did I gave you enough information about what I
want ?

Patrice
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