the annoying, verbose self

Paul Boddie paul at boddie.org.uk
Sat Nov 24 21:36:54 CET 2007


On 24 Nov, 20:10, "Patrick Mullen" <saluk64... at gmail.com> wrote:
>
> Yes, that's no good.  So you would write it like so:
>
> def meth(self,*args):
>     tmp = int(raw_input('Enter age:'))
>     using self:
>         age = tmp
>
> Still an unnecessary lookup on tmp though :)

Indeed. As has been mentioned, it's all about resolving names and how
much of that work gets done at run-time (and whether the magic
confuses the human reader further).

>                                               And it would be useless
> to use it for one assignment, the idea is to eliminate all the typing
> with this:
>
> self.var1 = 5
> self.var2 = "a value"
> self.var3 = stuff
> self.var4 = [2,54,7,7]
> self.var5 = "dingaling"
> self.var6 = 6.4
> self.var7 = 1
> self.var8 = False
> self.var9 = True
>
> Of course that "self.var3 = stuff" under the using would result in a
> bad lookup for "stuff", but the programmer who wanted to use this
> would have to realize this and try to avoid it.

I think the remedy is worse than the ailment, especially since the
Pascal "with" construct can make use of declared information about
structure attributes, while the absence of such declarations leaves
more work to be done in Python (and more detective work for future
maintainers of code). Of course, for cases like the above, assuming
that one doesn't feel that lists or dictionaries are acceptable
alternatives to large numbers of instance attributes (which might not
have such regular naming), one might suggest a useful extension of the
attribute access syntax. Taking part of the above example and
rewriting...

self.(var1, var2, var3, var4) = 5, "a value", stuff, [2,54,7,7]

I'm sure Mr Schluehr can provide a working demonstration of this with
very little effort. ;-)

Paul

P.S. There were some proposals for generalisations of the attribute
access mechanisms using not completely different syntax, but I don't
recall them addressing the issue of accessing multiple attributes at
the same time, and the use of arbitrary expressions in place of the
attribute name (where a tuple is used above) gave a distinct feeling
of writing something similar to a combination of the worst aspects of
some shell language with some of the nastier parts of microcomputer
assembly language. Let us, therefore, not get too enthusiastic about
such ideas!



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