seeking deeper (language theory) reason behind Python design choice

[Peter J. Holzer]

On 2018-05-16 01:26:38 +0100, bartc wrote:
> On 15/05/2018 21:21, Peter J. Holzer wrote:
> > I have been programming in C since the mid-80's and in Perl since the
> > mid-90's (both languages allow assignment expressions). I accumulated my
> > fair share of bugs in that time, but AFAIR I made this particular error
> > very rarely (I cannot confidently claim that I never made it). Clearly
> > it is not “a total bug magnet” in my experience. There are much bigger
> > problems in C and Perl (and Python, too). But of course my experience is
> 
> All those languages use = for assignment and == for equality.
> 
> If like me you normally use a language where = means equality (and := is
> used for assignment), then you're going to get it wrong more frequently when
> using C or Python (I don't use Perl).

Absolutely. These days I program mostly in Python and Perl and find that
I often omit semicolons in Perl. If I was programming in Pascal and C I
probably would mix up “:=”, “=” and “==”. But I don't. All the programming
languages I have used regularly (C, Perl, Java, JavaScript, Python) use
the same operators for assignment and comparison. So my fingers know what
to type.

(I wonder whether the notion that “=” and “==” are easy to mix up stems
from the early days of C when C was an outlier (most other languages at
the time used “=” for equality). Now C is mainstream and it's those other
languages that seem odd.)

> You might get it wrong anyway because = is used for equality in the real
> world too.

Not after a few years of programming. Probably not even after a few
weeks of programming. You develop muscle memory quite quickly. 

        hp

-- 
   _  | Peter J. Holzer    | we build much bigger, better disasters now
|_|_) |                    | because we have much more sophisticated
| |   | hjp at hjp.at         | management tools.
__/   | http://www.hjp.at/ | -- Ross Anderson <https://www.edge.org/>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: not available
URL: <http://mail.python.org/pipermail/python-list/attachments/20180519/a8d5acc4/attachment.sig>