Hi Brian, One instance where (1) would be useful is, when trying to implement a PostScript interpreter. The Postscript "eq" operator has to test whether two PostScript arrays share the same storage, rather than whether they contain the same values [*]. If you can do (1), you can use Go slices to implement PostScript arrays in a straightforward way.
[*] see page 580 of the PLRM: https://www.adobe.com/jp/print/postscript/pdfs/PLRM.pdf#page=594 All the best, Jochen On Sunday 11 August 2024 at 13:34:33 UTC+1 Brian Candler wrote: > Are there many instances where interpretation (1) is useful? > > I would also observe: if Go implemented case (2) for "==", this doesn't > prevent the user from implementing case (1) using a separate function, as > today. > > Supplementary question: does the Go standard library even expose a > function for case (1), or would you have to do it yourself using e.g. > unsafe.SliceData? Clearly case (2) is supported via bytes.Equal, > slices.Equal etc. > > On Sunday 11 August 2024 at 05:08:26 UTC+6 Ian Lance Taylor wrote: > >> On Fri, Aug 9, 2024 at 9:03 PM 'Brian Candler' via golang-nuts >> <golan...@googlegroups.com> wrote: >> > >> > I would agree, except there is no == operator defined on slices, and >> I'm not really sure why that is. The semantics I would expect are >> straightforward: i.e. length is the same, and the first 'len' slice >> elements compare as equal, recursively if necessary. (*) >> >> There is no == operator on slice types because there are two possible >> meanings: >> 1) Two slices are equal if they have the same length and refer to the >> same underlying array. >> 2) Two slices are equal if they have the same length and each >> individual element is itself equal. >> >> Because it's not clear which definition of equality people might mean, >> the language doesn't define ==, and forces people to choose which >> definition they want in any given situation. >> >> Ian >> > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/d3d24537-a48a-41d5-84d5-9bb170eaaae6n%40googlegroups.com.
