[Tutor] declare a variable inside a class

[richard kappler]

Thanks for the reply Martin, and in this instance I cannot post the actual
code (company rules). What I can do is say that with the xslt variable
defined within the formatter method, everything works, but when I pull it
out and put it in the upper level of the class, it gives me a traceback
that says the global variable xslt is not defined. Does that help?

regards, Richard

On Thu, Feb 11, 2016 at 3:43 PM, Martin A. Brown <martin at linux-ip.net>
wrote:

>
> Hi there again Richard,
>
> [snipped a bit of stuff]
>
> >The method that actually formats the messages opens the xslt file,
> >then uses it to format the message. Clever boy that I am, I figured
> >it would be better to open the xslt file once, rather than once per
> >message, so I moved the line
> >
> >xslt = ('path/to/xslt.file')
>
> Yes, this is a good idea.
>
> >out of the method it was in and up to the top level of the class, to wit:
> >
> >class MyClass():
> >
> >    xslt = ('path/to/xslt.file')
> >
> >   def a_bunch-of-methods():
>
> An impossible method name.  That would be a syntax error.
>
> >and so on.
> >
> >Obviously this didn't work,
>
> Why is it obvious?  What was obvious to me is the syntax error, but
> that does not appear to be what you are asking.
>
> What was the error message?
>
> >when the formatting method was called, it through an exception that
> >the variable xslt wasn't defined. This is my first not-a-toy try at
> >OOP, I could use a clue.
>
> So, before addressing your question, could I gently recommend that
> you post your actual code (clean up any variables or data that you
> don't want the public to see), whether it is running or not, along
> with any error messages (pasted, please).
>
> This is just a reminder, that this reduces the guesswork on the part
> of the members of the list.
>
> I think your problem is simply not knowing the name of the variable
> you called 'xslt'.  Perhaps the below example helps?
>
> -Martin
>
> #! /usr/bin/python3
>
> class MyClass(object):
>
>     xslt = '/usr/share/nmap/nmap.xsl'
>
>     def find_xslt(self):
>         print(xslt)
>
>     def oh_there_it_is(self):
>         print(self.xslt)
>
>     def redefine_in_instance(self):
>         self.xslt = '/usr/share/sgml/X11/xorg.xsl'
>
> if __name__ == '__main__':
>
>     # -- instantiate the class
>     c = MyClass()
>
>     # -- this is what I think you were doing
>     try:
>         c.where_is_xslt()
>     except AttributeError:
>         pass
>
>     # -- but, try locating the class attribute through self
>     c.oh_there_it_is()
>
>     # -- class attribute can be overridden in instances....
>     c.redefine_in_instance()
>     c.oh_there_it_is()
>
>     # -- newly defined instances will get the default class attribute
>     d = MyClass()
>     d.oh_there_it_is()
>
> --
> Martin A. Brown
> http://linux-ip.net/
>



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