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Re^5: ref to read-only alias ... why? (notabug)

by LanX (Chancellor)
on Jan 06, 2012 at 17:49 UTC ( #946638=note: print w/replies, xml ) Need Help??


in reply to Re^4: ref to read-only alias ... why? (notabug)
in thread ref to read-only alias ... why?

Thats what I expected.

> I wonder why.

IMHO legacy code would break if you die here.

But a warning would be great.

Cheers Rolf

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Re^6: ref to read-only alias ... why? (notabug)
by dk (Chaplain) on Jan 06, 2012 at 18:08 UTC
    I agree on a warning, it would be a practical thing, after all. And after that, a real fix with 'die' a couple versions later should help the legacy code.

    Well anyway, I found the code suggested by ikegami, so would you guys review the patch please?

    --- pp.c.0 2012-01-06 01:07:34.511988700 +0100 +++ pp.c 2012-01-06 19:04:06.311428300 +0100 @@ -515,9 +515,11 @@ SvTEMP_off(sv); SvREFCNT_inc_void_NN(sv); } - else if (SvPADTMP(sv) && !IS_PADGV(sv)) + else if (SvPADTMP(sv) && !IS_PADGV(sv)) { + Perl_ck_warner(aTHX_ packWARN(WARN_MISC), + "Implicit copy of a read-only scalar due to aliasing"); sv = newSVsv(sv); - else { + } else { SvTEMP_off(sv); SvREFCNT_inc_void_NN(sv); }
        Could you please clarify which the "working case" is in your opinion?

        I agree with tye that there are good arguments for both perspectives.

        Cheers Rolf

        Well, I give up then.

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[james28909]: i forgot how to link my scratch pad
[Lady_Aleena]: [pad://]
[james28909]: my scratchpad
[james28909]: and like i say, is just an example, not working code, but hopefully you understand what i mean. :)
[james28909]: and like i say, it would be alot of work to get around renaming 3 subs haha
[Lady_Aleena]: Well, you would have to add the file munging and a lot more.
[james28909]: yeah but it would rename those subs xD
[Lady_Aleena]: I'd say, go back to my scratchpad, and really look at what the 3 subs are doing, then play. Meanwhile, I am going afk for about an hour +/- a few minutes.

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