On Thu, 08 May 2014 10:35:46 +1000, Ben Finney wrote:
> Marko Rauhamaa <ma...@pacujo.net> writes:
>
>> Ben Finney <b...@benfinney.id.au>:
>>
>> > That's why I always try to say “Python doesn't have variables the way
>> > you might know from many other languages”,
>>
>> Please elaborate. To me, Python variables are like variables in all
>> programming languages I know.
>
> Many established and still-popular languages have the following
> behaviour::
>
> # pseudocode
> foo = [1, 2, 3]
> bar = foo # bar gets the value [1, 2, 3]
> assert foo == bar # succeeds
> foo[1] = "spam" # foo is now == [1, "spam", 3]
> assert foo == bar # FAILS, ‘bar’ == [1, 2, 3]
Pascal and Fortran are examples of this.
Any more recent examples? Any examples of languages with dynamic typing
but this behaviour?
I note also that one may still have a name-binding model with copy-on-
assign semantics. For example, one might add syntactic sugar to a Python-
like language such that:
spam = eggs
is a name binding, and
spam := eggs
makes a copy of eggs before binding.
--
Steven D'Aprano
http://import-that.dreamwidth.org/
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