[Tutor] Equivalent to perl -e

[Chris Lasher]

Points well taken. In fact, the example he demonstrated to me as a
one-liner was a regular expression as a line filter in
Emacs--essentially just a grep. There's no Pythonic equivalent to
this. Right tool for the right job, as you said. He was half-joking
about not learning Python if it lacked the option to execute snippets.

His lab maintains a significant amount of Perl code; he was intrigued
by my zealous enthusiasm for Python and my assertion that, personally,
I experienced greater long-term readability with my scripts written in
Python over those written in Perl. I think once he begins to
experience Python he will come to understand why it's not suited for
one-liners, and why that's a Good Thing.

Excellent reply!

Chris


On 10/15/06, Tim Peters <tim.peters at gmail.com> wrote:
> [Chris Lasher]
> > My professor and advisor has been "inspired" by me to give Python a
> > try. He's an avid Perl user, and challenged me with the following:
> >
> > What is the Python equivalent to perl -e '<some oneliner>'?
>
> The initally attractive but unsatisfying answer is:
>
>     python -c '<some oneliner>'
>
> The reason it's "unsatisfying" is that Python isn't concerned with making:
>
>     <some oneliner>
>
> pleasant, or even sanely possible, for many tasks.  Perl excels at
> one-liners; Python doesn't much care about them.
>
> > Embarassingly, I had no answer, but I figure, someone on the list will
> > know. His use of Python is at stake; he threatened that, since he's
> > dependant enough on using perl -e within Emacs enough, if it can't be
> > done in Python, he won't take the language seriously. Help me, Python
> > Tutor, you're his only hope!
>
> Like many Python (very) old-timers, I used Perl heavily at the time
> Python came out.  As was also true for many of them, as time went on
> the size of a new program I was willing to write in Perl instead of in
> Python got smaller and smaller, eventually reaching "almost 0".  I
> still use Perl some 15 years later, but now /only/ for "perl -e"-style
> 1-liners at an interactive shell.  If it takes more than a line, I
> stick it in a module (and maybe a class) for reuse later.
>
> Python's strengths are more in readability, helpful uniformity, easy
> use of classes and rich data structures, and maintainability.  Cryptic
> one-liners are in general (but not always) opposed to all of those.
>
> So, ya, "python -c" exists, but your professor won't be happy with it.
>  That's fine!  If one-liners are all he cares about, Perl is usually
> the best tool for the job.
>