Hi pants team! I'm taking over this effort to upgrade our code base from python 3.6 to 3.7, but have gone through the process to upgrade pants first in hopes that newer versions (like 1.30) of pants provide some better support and ability to compile c++ code using cython. The same files that Zack had linked are still in use and haven't changed, however the error that pants throws is as follows:

21:15:57 [INFO] initializing pantsd...
21:15:57 [INFO] pantsd initialized.
21:15:58 [ERROR] 1 Exception encountered:

  UnrecognizedTargetTypeException: Target type 'compile_cython' is not registeredfor address submodules/obscura-plugins/plugins:compile-plugins.

All valid target types: ['_python_requirements_file', 'alias', 'annotation_processor', 'benchmark', 'credentials', 'ctypes_compatible_c_library', 'ctypes_compatible_cpp_library', 'external_native_library', 'files', 'jar_library', 'java_agent', 'java_library', 'java_protobuf_library', 'java_thrift_library', 'javac_plugin', 'junit_tests', 'jvm_app', 'jvm_binary', 'jvm_prep_command', 'managed_jar_dependencies', 'netrc_credentials', 'node_bundle', 'node_module', 'node_preinstalled_module', 'node_remote_module', 'node_test', 'packaged_native_library', 'page', 'prep_command', 'python_app', 'python_binary', 'python_dist', 'python_grpcio_library', 'python_library', 'python_requirement_library', 'python_tests', 'python_thrift_library', 'remote_sources', 'resources', 'scala_library', 'scalac_plugin', 'target', 'unpacked_jars', 'unpacked_whls']

(If 'compile_cython' is a custom target type, refer to <https://groups.google.com/forum/#!topic/pants-devel/WsRFODRLVZI> for instructions on writing a light-weight Target API binding.)

(Use --print-exception-stacktrace to see more error details.)

I've looked at the link and docs for adding a new custom target type as well as the solution posted in the thread to the previous slack conversation, however being new to pants, I'm not exactly sure how to go about adding the existing

compile_cython

code that we have as a valid target type so we can build the c++ code.

Hi, welcome! We are glad to help. Could you share what you have so far, including your original target definition for

compile_cython

?

It's still defined like this: http://ix.io/3PIi The compile cython code is also the same: http://ix.io/3PIj

That second link did not work It would help if you can please share the contents of

from cython.compile_cython

Ah ok. Let me generate a new link really quick, sorry about that

Yes 🙂 Great so this will be fairly simple: everything is the same as

python_library

other than rhe new

output

field. What is the type of that? Like are people typing strings, a list of strings

As far as I know the output from this part is a bunch of cythonized c++ code saved to disk so that tests/pex can use them.

OK cool, that is all we need to know that it is a string you will do this

class CythonOutputV2Field(StringField):
    alias = "output"
    help = "fill this in"

class CompileCythonV2Target(Target):
    alias = "compile_cython"
    help = "fill me in"
    core_fields = (CythonOutputV2Field, *PythonLibrary.core_fields)

then in `register.py`:

def target_types():
    return [CompileCythonV2Target]

In the registry file?

Oops I sent early. The first snippet can be wherever

Ah ok, That makes sense. I'll give that a shot, thanks!

Target

and

StringField

come from

pants.engine.target

. Note that there is a v1 version of

Target

and v2. You may want to do

from pants.engine.target import Target as TargetV2

I added the code as suggested but received this error when trying to list out the target types.

What does your register.py look like now? To be clear, you should not change the original target definition you had nor

build_file_aliases

in

register.py

. There should only be a new code. You are writing "bindings"

Yeah, I only added new code. register: https://www.codepile.net/pile/v9JYRVGl compile_cython: https://www.codepile.net/pile/rkA3qAY2

for the v1 definition, you need to still use

from pants.backend.python.targets.python_library import PythonLibrary

. You are using the V2 class. You will need to do the

from as

import thing

Ok, I was able to get the

compile_cython

to show up in the target types after I fixed that. I'll try running my tests now to see if pants does what I need it to do