is the only difference between the 2.7.0

python_library

and the 2.8.0

python_sources

just the name? it /feels/ like everything works differently

It does work differently since the implementation of file targets has been generalized into “target generators.” This is mostly visible only to plugin authors. In 2.7.x and earlier versions,

python_library

represented multiple source files and there were “subtargets” addressable on the command-line via file specs (i.e., the name of the file). These file subtargets were a special case in the engine. In 2.8.x, per-file subtargets have been generalized into “target generators” where a target can dynamically create other targets.

python_sources

is a target generator that generates

python_source

targets (which represent each Python file). One of the motivations for the feature was for the Go backend. The

go_mod

target is a target generator which generates targets for the packages in third-party dependencies. This allows those packages to be part of the build graph so that Pants knows the dependencies among them. This is an example of a target generator that does not generate per-file targets (since the “unit of build” in Go programs is the package).

but in terms of how they operate,

python_library

and

python_sources

should be identical.

Hi! Yeah, indeed, there should be few practical changes other than the rename. These things are now possible, but not necessary to use: • you can directly create a

python_source

and

python_test

target • you can set `overrides`:

python_tests(
   name="tests",
   overrides={
      "foo_test.py": {"timeout": 120},
      ("bar_test.py", "baz_test.py"): {"timeout": 200},
   },
)

The other changes are: •

./pants peek

will have different

target_type

for some targets. Whereas

./pants peek path/to/f_test.py

used to say

python_tests

, now it's

python_test

•

./pants filter --target-type

differentiates between

python_source

vs.

python_sources

• The globs

./pants $goal dir:

now matches "generated targets" with goals like

list

and

peek

when using

dir:

and

dir::

, whereas we used to leave them off What changes are you seeing?