basic class question..

[Pyrot]

On 11월15일, 오후10시15분, Tim Chase <python.l... at tim.thechases.com> wrote:
> Pyrot wrote:
> > class rawDNA:
> >    import string
> >    trans = string.maketrans("GATC","CTAG")
>
> >    def __init__(self, template = "GATTACA"):
> >            self.template = template  //shouldn't this make "template"
> > accessible within the scope of "rawDNA"??
>
> No.  Python's scope resolution consists only of "local, global,
> or explicit".  There is no "try to find this in the instance or
> class" scope-resolution guessing.  Your code makes "template"
> accessible within the scope of "self", not in a global
> unqualified scope.
>
> So this:
>
> >    def noncoding(self):
> >            print template.translate(trans)  //
>
> tries to reference "template" first in the local scope (within
> noncoding(), but it doesn't exist there), then in the global
> scope (it also doesn't exist there), and stops.
>
> It should be as you have it here:
>
> > class rawDNA:
> >    import string
> >    trans = string.maketrans("GATC","CTAG")
> >    def __init__(self, template = "GATTACA"):
> >            self.template = template
> >    def noncoding(self):
> >            print self.template.translate(trans)
>
> Here, you start with "self" which *is* in the local scope, which
> *does* contain "template" and so it successfully finds it and all
> is [qualifiedly] good.  However, you'll also find that "trans"
> isn't found because it's neither in the local nor global scope:
>
>    >>> class RawDNA:
>    ...     import string
>    ...     trans = string.maketrans("GATC", "CTAG")
>    ...     def __init__(self, template="GATTACA"):
>    ...             self.template = template
>    ...     def noncoding(self):
>    ...             print self.template.translate(trans)
>    ...
>    >>> r = RawDNA()
>    >>> r.noncoding()
>    Traceback (most recent call last):
>      File "<stdin>", line 1, in <module>
>      File "<stdin>", line 7, in noncoding
>    NameError: global name 'trans' is not defined
>
> so you need to fully qualify it as "RawDNA.trans" for Python to
> find it.  (I also shifted to using the PEP-8 naming convention
> "RawDNA" instead of "rawDNA").
>
> Which you indeed discovered:
>
> > this works as intended.
>
> Being explicit is part of "Python Zen"  (from the python
> command-prompt, type "import this" to see the whole list)
>
> -tkc

thanks!

one last question, is "self.template.translate(trans)" the right way
to go(pythonic?)?
I found it to be cumbersome(and a mouthful) and thought I might have
been doing it wrong :-)