Re: Shouldn't references be readonly?

in reply to Shouldn't LITERAL references be readonly? (updated)

My take on this: "Literal references" don't exist in Perl, at least they don't appear in perldata. A literal reference would be something like ARRAY(0x557782f0a4c8), but you can't feed this to Perl.

The constructs {...} and [...] are anonymous, but not literals.

I fail to see a point in clobbering anonymous variables, but then I also fail to see why Perl should prevent it.

Comment on Re: Shouldn't references be readonly?

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Re^2: Shouldn't references be readonly? by LanX (Saint) on Aug 05, 2020 at 11:41 UTC
`[1,2,3]` is called a literal array in many languages like for instance JavaScript. Since Perl has both an explicit $reference and a @list form of its data structures, it might be difficult to point out "the" literal form. > I also fail to see why Perl should prevent it. For the same reason why it's prevented with other readonly values like literal scalars ... to catch bugs with aliases. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l]
Re^3: Shouldn't references be readonly? by dave_the_m (Monsignor) on Aug 05, 2020 at 17:33 UTC
Perl doesn't have literal arrays. It has constructors which will create a reference to an anonymous array, where the elements of that array are initially assigned to by copying the values from a list which may or may not be literal. E.g. `$ar1 = [ 1,2,3 ]; $ar2 = [ 1,2,3,$four ];` [download] Should @$ar1 and @$ar2 be treated differently, and if so, why? Dave.	[reply] [d/l]
Re^4: Shouldn't references be readonly? by LanX (Saint) on Aug 05, 2020 at 17:56 UTC
> Should @$ar1 and @$ar2 be treated differently, No, but what's the point to allow overwriting an alias for references without throwing an error? Should they be treated differently than 42, undef and "str", and if so, why? Again, I'm talking about the container, not the mutable content. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply]
Re^5: Shouldn't references be readonly? by dave_the_m (Monsignor) on Aug 05, 2020 at 18:32 UTC
Re^6: Shouldn't references be readonly? by LanX (Saint) on Aug 05, 2020 at 18:44 UTC
Re^6: Shouldn't references be readonly? by LanX (Saint) on Aug 05, 2020 at 20:29 UTC
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Re^4: Shouldn't references be readonly? by LanX (Saint) on Aug 05, 2020 at 18:30 UTC
> 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 Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply]
Re^5: Shouldn't references be readonly? by dave_the_m (Monsignor) on Aug 05, 2020 at 18:38 UTC
Re^6: Shouldn't references be readonly? (updated) by LanX (Saint) on Aug 05, 2020 at 18:51 UTC
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Re^3: Shouldn't references be readonly? by haj (Vicar) on Aug 05, 2020 at 14:59 UTC
For the same reason why it's prevented with other readonly values like literal scalars ?? As you have demonstrated, anonymous references are not readonly, so Perl does not prevent them from being overwritten. I still don't see a compelling reason why they should be read-only. Can you provide an example for "catching bugs with aliases"?	[reply]
Re^4: Shouldn't references be readonly? by LanX (Saint) on Aug 05, 2020 at 15:54 UTC
> compelling reason why they should be read-only. Again, what is the compelling reason to throw an error with aliased 1 or "string" or undef??? The OP has an example. Same league, it's not more logical at all. Probably some implementation detail related to magic edge-cases like auto-vivification or so. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply]
Re^5: Shouldn't references be readonly? by haj (Vicar) on Aug 05, 2020 at 17:58 UTC
Re^6: Shouldn't references be readonly? by LanX (Saint) on Aug 05, 2020 at 18:03 UTC
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Re^5: Shouldn't references be readonly? by jo37 (Deacon) on Aug 05, 2020 at 18:11 UTC
Re^6: Shouldn't references be readonly? by LanX (Saint) on Aug 05, 2020 at 18:20 UTC
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