seeking deeper (language theory) reason behind Python design choice

[Python]

On Sun, May 13, 2018 at 11:05:48AM +0000, Steven D'Aprano wrote:
> On Sat, 12 May 2018 21:42:13 -0500, Python wrote:
> 
> > Responding to this further would essentially just require me to
> > reiterate what I already wrote--I won't do that.  I'll simply maintain
> > that in my rather lenghty experience, this mistake has actually been
> > rather rare and has to my knowledge *never* caused a support issue
> > requiring a bug fix to production code in projects I've been associated
> > with.  It's a useful construction whose detriment has, IMO, been
> > completely overblown.
> 
> I already linked to the attempt to install a backdoor in the Linux kernel 
> with this, but even for accidental errors, thirty seconds on the CVE 
> database finds at least one real-world example:
> 
> https://www.cvedetails.com/cve/CVE-2009-4633/
> 
> I expect that these days it will be rare, since most C compilers would 
> default to warning about it if you run with warnings enabled.

A couple of anecdotes is a very far way off from making the case.
Either the code was not reviewed or the reviewer was careless.  And
I'm not saying it never happens, I'm saying it's not any worse than
any other possible bug, and far less common in practice than plenty of
other classes of bugs.  I'm also not saying that you couldn't use a
different operator that's less likely to cause confusion.  I *am*
saying this is a useful feature that I find myself wanting very often.
Obviously since there's a PEP about a way to provide exactly this
feature, plenty of people consider it a worthwhile feature to have.

Yes, bugs happen.  Eliminating useful constructs from the language is
not a good way of dealing with that problem.