On Tue, 2006-11-28 at 18:28 +0000, Ross Paterson wrote: > On Tue, Nov 28, 2006 at 12:28:56AM +0000, Duncan Coutts wrote: > > It's not clear to me that we need to have an extra field. I had > > originally envisaged that cabal-setup would just find the right compiler > > to build Setup.(l)hs and if there was none that it'd use defaultMain > > (possibly without needing to compile any setup binary). > > If there was a Setup.[l]hs, it wouldn't be correct to use defaultMain, > would it?
Indeed, it would not. If there's a Setup.[l]hs then we use that. If there isn't then we use Distribution.Simple.defaultMain (either directly or indirectly via a simple Setup.hs). > > So do we really need a 'build-type:' field? Arn't there just two values > > for it, 'Simple' and 'Custom' (since all others are just different > > implementations of 'Custom')? > > In that sense, there's only one value (Custom), but defaultMain is > common, and a reasonable number of packages use > > main = defaultMainWithHooks defaultUserHooks which (bizarrely) is not the same as defaultMainWithHooks defaultUserHooks, though it really should be. > I had a value for Distribution.Make.defaultMain too (but I don't know > if anyone uses that). > > > Can't the Simple/Custom distinction be simply if the Setup.(l)hs is > > present or not? > > If you have a field, cabal-setup can avoid compiling Setup.[l]hs in the > common cases. Oh you mean that since people would want to be backwards compatible that they would include a simple Setup.hs and then we loose the advantage of not having to compile Setup.hs and thus having an extra field to say to use simple even if there is a Setup.hs present is a benefit? Yes, it is a benefit but it seems rather marginal to me. Remember that we can't always avoid building a trivial Setup.hs anyway, since in the case that cabal-setup was built with Cabal-x.y and the .cabal requests cabal version x.y+1 then cabal-setup needs to build Setup.hs with the later version of the Cabal lib and use that. Duncan _______________________________________________ cabal-devel mailing list cabal-devel@haskell.org http://www.haskell.org/mailman/listinfo/cabal-devel
