#697: Add "cabal install --only-dependencies" flag ---------------------------------+------------------------------------------ Reporter: igloo | Owner: Type: enhancement | Status: new Priority: normal | Milestone: Component: cabal-install tool | Version: HEAD Severity: major | Keywords: Difficulty: unknown | Ghcversion: Platform: | ---------------------------------+------------------------------------------ Comment(by duncan): It should not be too hard to add a flag to cabal install that builds just the dependencies of the given packages. I was thinking about it the other day. It ought to be relatively straightforward. It would involve modifying the install plan before running it. The only question is what behavior we want when one target depends directly or indirectly on another. The use case is presumably to install all dependencies so that local versions can be configured and built. Here are two scenarios: {{{ packageA -> packageB -> packageC cabal install --only-dependencies packageA packageB cabal install --only-dependencies packageA packageC }}} In the first scenario it is clear that we should just install `packageC`. The user can then configure and install the other two. However in the second case we have an intermediate dependency `packageB`. We would normally want to install this, but that would require that we also install `packageC` which is one of the ones we do not want to install, since the user wants to do that themselves. So one option is to fail in this case, the other is to install `packageB` and `packageC`. Is it obvious which we should do? Do people need both behaviours in different circumstances? -- Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/697#comment:1> Hackage <http://haskell.org/cabal/> Hackage: Cabal and related projects

#697: Add "cabal install --only-dependencies" flag ---------------------------------+------------------------------------------ Reporter: igloo | Owner: Type: enhancement | Status: new Priority: normal | Milestone: Component: cabal-install tool | Version: HEAD Severity: major | Keywords: Difficulty: unknown | Ghcversion: Platform: | ---------------------------------+------------------------------------------ Comment(by j3h): Please excuse the accidental double form submission, the two attached files are identical. The patch implements an `--only-dependencies` flag for the `install` command. My resolution for the case that Duncan described above, where a user requests dependencies only and then specifies a necessary dependency on the command line, installation fails with an error message. In addition to the options that Duncan mentioned for this case, there is a third option, which is to install only the dependencies that can be satisfied ''without'' installing any explicitly mentioned package. The behavior in this case is not very important to me, because I expect only to use this flag when actively developing a package, so the only excluded package would be the root of the dependency DAG, which can always be safely removed. It occurs to me as well that another sensible interface to this functionality (especially for development purposes) would be {{{ cabal configure --install-missing-dependencies }}} -- Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/697#comment:3> Hackage <http://haskell.org/cabal/> Hackage: Cabal and related projects

#697: Add "cabal install --only-dependencies" flag ---------------------------------+------------------------------------------ Reporter: igloo | Owner: Type: enhancement | Status: new Priority: normal | Milestone: Component: cabal-install tool | Version: HEAD Severity: major | Keywords: Difficulty: unknown | Ghcversion: Platform: | ---------------------------------+------------------------------------------ Changes (by basvandijk): * cc: v.dijk.bas@… (added) Comment: Just added myself to the CC list to indicate my support for this ticket and the patch by j3h. BTW note that the Gentoo Linux `emerge` command also has a similar flag: {{{ --onlydeps (-o) Only merge (or pretend to merge) the dependencies of the packages specified, not the packages themselves. }}} -- Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/697#comment:5> Hackage <http://haskell.org/cabal/> Hackage: Cabal and related projects

#697: Add "cabal install --only-dependencies" flag ---------------------------------+------------------------------------------ Reporter: igloo | Owner: Type: enhancement | Status: closed Priority: normal | Milestone: cabal-install-0.10 Component: cabal-install tool | Version: HEAD Severity: major | Resolution: fixed Keywords: | Difficulty: unknown Ghcversion: | Platform: ---------------------------------+------------------------------------------ Comment(by elga): * [http://www.releve-identite-operateur.fr/rio-bouygues.html rio bouygues] -- Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/697#comment:7> Hackage <http://haskell.org/cabal/> Hackage: Cabal and related projects