I'm still not convinced, but this PEP has been WIP for too long. I think it should be marked Accepted.
On Aug 17, 2017 9:51 PM, "Nick Coghlan" <ncogh...@gmail.com> wrote: > On 18 August 2017 at 02:05, 12345 67890 <xov...@gmail.com> wrote: > > After reviewing the PEP, I personally feel that it relies too much on the > > backend Doing The Right Thing. As it currently stands, it is my > > understanding that the build backend is called in the source directory > and > > is then responsible for handling the entire process to build a compliant > > wheel. In a PEP 517 world, the build backends may be poorly written > > initially and may not fully comply with the PEP’s goal to produce the > same > > wheel that would be produced from an sdist. > > > > Current process: > > > > Frontend calls backend in source directory build-wheel > > The PEP *allows* this, but it doesn't *require* it. > > > Proposed process: > > > > Frontend copies source tree to temporary directory > > Frontend invokes build-sdist to build an sdist > > Frontend extracts sdist to new temporary directory > > Frontend reloads backend from sdist directory and invokes build-wheel > > A particularly paranoid front-end remains free to work this way if it > wants to. > > From the PEP's point of view, it's just four distinct operations: > > Step 0: make a copy of the original source tree > Step 1: build an sdist from the copied source tree > Step 2: unpack the sdist > Step 3: build a wheel from the unpacked sdist > > > The proposed process is more computationally intensive, but moves > compliance > > logic out of the build backend. In addition, we can make some > modifications > > based on this proposed process: > > > > * Remove parameter for build_dir in build_wheel since it is always the > current > > directory > > We've had that discussion - build_dir models something different from > what you propose (specifically, it's designed to invoke the backend's > native out-of-tree build support, when that's what the frontend > actually wants to invoke. If a frontend doesn't want that, don't use > the setting) > > > Optimization: add new parameter to build_sdist called copy_extra, that > when > > set to false, only includes files in sdist needed to build a wheel. > > No, this is the operation we decided makes no sense (and hence removed > from the latest iteration of the PEP), because no build system we > could find actually provides it natively. > > That means it would necessarily be a Python-specific capability > anyway, and that further means that any backend which could be trusted > to implement this feature correctly can instead be trusted to > implement building an sdist or wheel directly from a source tree > correctly. > > It's also not a major concern if early backend iterations *don't* do > things correctly - those errors will be reported as bugs, fixed > versions of the backends will be released, and future builds will > start doing the right thing. > > > Specify that build_wheel should fail if PKG-INFO is not present so that > it > > is always invoked in an sdist > > No, we don't want to make that a mandatory requirement, since > frontends are already free to enforce that rule if they want to (by > checking for PKG-INFO before they call build_wheel), and particular > backends are also free to enforce it for the packages they manage (by > raising NotImplemented when they don't find PKG-INFO). > > Cheers, > Nick. > > -- > Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia >
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