Deep vs. shallow copy?

Steven D'Aprano steve+comp.lang.python at
Thu Mar 13 00:07:53 CET 2014

On Wed, 12 Mar 2014 15:29:59 +0000, Alex van der Spek wrote:

> Having been taught programming in Algol60 Python still defeats me at
> times! Particularly since Algol60 wasn't very long lived and what came
> thereafter (FORTRAN) much worse.

Fortran came first. Fortran was the first high-level language which 
allowed the programmer to write things that looked rather like the sorts 
of mathematical expressions they were used to.

There were a few higher-level assembly languages that came before 
Fortran, such as SpeedCoding, Fortran's predecessor, but Fortran was the 
first truly high-level programming language, and even in 1957 it came 
with an optimizing compiler.

I'm not really familiar with Algol, but I do know Pascal, and you should 
think of the append method to be like a Pascal procedure. Because Python 
doesn't have true procedures, it follows the convention that returning 
the special object None signals the intention to return nothing at all. 
Hence your example below:

>>>> c = a.append(b)
>>>> print c
> None

Steven D'Aprano

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