Re^4: Shouldn't references be readonly?

[LanX]

> Perl doesn't have literal arrays ... a reference to an anonymous array,

Perlglossary

literal

A token in a programming language, such as a number or string, that gives you an actual value instead of merely representing possible values as a variable does.

anonymous

Used to describe a referent that is not directly accessible through a named variable. Such a referent must be indirectly accessible through at least one hard reference. When the last hard reference goes away, the anonymous referent is destroyed without pity

[dave_the_m]

Which of the following do you regard as a literal array:

[]
[1,2,3]
[1,2,$x]

I regard none of them as literal. [] {} are constructors; they are just syntactic sugar for a function which takes a list and returns a reference to an anonymous aggregate, e.g.

[1,2,3]
# is the same as
anon_array(1,2,3);
sub anon_array { my @a = @_; \@a }

Dave.

[LanX]

They are all literal reference constructors the content is mutable.

Please compare the analogue situation in JS where [] and {} explicitly documented as "literal".°

See also Readonly which makes the explicit distinction about overwriting a variable holding an array and protecting the deep content.

UPDATE

°)

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Array

Arrays can be created using the literal notation:

let fruits = ['Apple', 'Banana'];

console.log(fruits.length); // 2
console.log(fruits[0]);     // "Apple"

[dave_the_m]

All I can say is that I personally strongly disagree with your use of term "literal" in this context, and I think that any attempt to draw an analogy between 1 and 1 is specious. The former is a literal value appearing in the source code and used as a compile-time constant. The latter is a run-time list constructor.

But regardless of that, there is still the question of whether the reference returned by [] and {} should be marked readonly. I suppose it could be but Larry never thought to do so, and there doesn't seem any point in changing it now.

Dave.