[Python-ideas] Hooking between lexer and parser

Nick Coghlan ncoghlan at gmail.com
Mon Jun 8 06:18:15 CEST 2015

On 8 June 2015 at 13:10, Robert Collins <robertc at robertcollins.net> wrote:
> In this particular case, given Nick's comments about why we change the
> guts here, I'd say that 'worth doing eventually' is not in consensus,
> and I personally think that anything that is 'in the indefinite
> future' is almost never more important than problems affecting people
> today, because its a possible future benefit vs a current cost.
> There's probably an economics theorem to describe that, but I'm not an
> economist :)

I don't know about economics, but for anyone that hasn't encountered
it before, the phrase YAGNI is a good one to know: You Ain't Gonna
Need It. ( http://c2.com/cgi/wiki?YouArentGonnaNeedIt )

The way YAGNI applies when deciding *to* do something is when you're
faced with the following choice:

* Making a particular change solves an immediate problem, but would
make another possible change more complex in the future
* Not making a change preserves the simplicity of the possible future
change, but also doesn't solve the immediate problem

Sometimes you'll get lucky and someone will figure out a third path
that both addresses the immediate concern *and* leaves your future
options open for other changes. More often though, you'll have to
decide between these options, and in those cases "YAGNI" argues in
favour of heavily discounting the potential increase in difficulty for
a change you may never make anyway.


P.S. This tension between considering the long term implications of
changes without allowing that consideration to block near term
progress is what I personally see in the following two lines of the
Zen of Python:

    Now is better than never.
    Although never is often better than *right* now.

Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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