(--> https://metacpan.org/pod/ReadonlyX#ReadonlyX-vs.-Readonly)

And this aliasing of namespaces happens in his module

BEGIN { *ReadonlyX:: = *Readonly:: }
package          # hide from PAUSE
    Readonly;    # I wish...
[download]

that's unfortunate to word it mildly.

Especially since the author explicitly admits incompatibilities. (quote: "break 16 years of code out there in Darkpan.")

When another module loads the original Readonly, different implementations and prototypes will collide.

This "collides" with my understanding of a "drop-in-replacement".

If you want to use ReadonlyX, force it to use it's own namespace.

If there is no option for that, file a feature request.°

Regarding the strong wording of the PC-Policy - which I also dislike for its style- I doubt it originates in PBP.

And it seems to me this module is also far newer (2016) than Damian's book (2005), so please stop referencing it as justification.

°) I could also come up with a wrapper module which is fixing that by unaliasing the namespaces, but let's wait what the author says.

> that's unfortunate to word it mildly.

In hindsight, this is because Readonly is recommending fully qualified subs,

Readonly::Scalar   $sca => $initial_value;
Readonly::Array    @arr => @values;
Readonly::Hash     %has => (key => value, key => value, ...);
[download]

Any "drop-in replacement" supporting this must meddle with the namespace ... ugly!

Cheers Rolf
_{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)
Wikisyntax for the Monastery}