Target Addresses

Every Pants target has an address, which is a combination of the BUILD file path and target name. Addresses are used in two main contexts:

  • To reference targets as dependencies in BUILD files,
  • From the command-line, to specify what targets to act on.

The following target addresses all specify the same single target.

  • The fully qualified target address is // plus the BUILD file's directory path plus target name:

    $ ./pants list //src/python/myproject/example/hello/main:main
    src/python/myproject/example/hello/main:main
    
  • The starting double-slash is optional if the target isn't in the build root directory:

    $ ./pants list src/python/myproject/example/hello/main:main
    src/python/myproject/example/hello/main:main
    

    It's idiomatic to omit the double-slash when possible. However it's required when referencing targets in the build root, so that the command-line parser can distinguish such targets from goal names: ./pants foo bar baz is ambiguous; ./pants foo //:bar //:baz is not. That said, it's not necessary, or even common, to have targets at the build root, and this practice is best avoided anyway.

  • The target name is optional if it is the same as the parent directory name:

    $ ./pants list src/python/myproject/example/hello/main
    src/python/myproject/example/hello/main:main
    

    It's idiomatic to omit the repetition of the target name in this case.

  • Relative paths and trailing forward slashes are ignored on the command-line to accommodate tab completion:

    $ ./pants list ./src/python/myproject/example/hello/
    src/python/myproject/example/hello:app
    

    Absolute paths are also allowed on the command-line, to support flexibility in scripting:

    $ pants list $REPO_ROOT/src/python/myproject/example/hello
    src/python/myproject/example/hello:app
    

These last two forms are not allowed in target addresses in BUILD files. They are just for command-line convenience.

You can reference another target in the same BUILD file by starting with a colon :targetname instead of specifying the whole path:

java_library(
  name='application',
  ...,
 )

java_library(
  name='mybird',
  dependencies=[
    ':application',
  ],
)

Note that, apart from this shorthand, addresses in BUILD files are always relative to the buildroot, not to the referencing BUILD file.

Pants supports two globbing target selectors, as a convenience on the command-line. These forms are not allowed in BUILD files.

A trailing single colon specifies a glob of targets at the specified location:

$ ./pants list src/python/pants/util:
src/python/pants/util:argutil
src/python/pants/util:collections
src/python/pants/util:contextutil
src/python/pants/util:desktop
...

A trailing double colon specifies a recursive glob of targets at the specified location:

$ ./pants list src/python/pants/backend/project_info::
src/python/pants/backend/project_info/tasks:all
src/python/pants/backend/project_info/tasks:dependencies
src/python/pants/backend/project_info/tasks:depmap
...
src/python/pants/backend/project_info/rules:rules
src/python/pants/backend/project_info/rules:tests
src/python/pants/backend/project_info:plugin

Alternative: File args

Instead of specifying the address, you may instead simply specify the file you want Pants to operate on. Pants will find all owner(s) and operate over those owning targets.

$ ./pants list src/python/myproject/example.py
src/python/myproject:lib

You may pass multiple files and even use globs, with the same syntax as the sources field in BUILD files (see Use globs to group files):

# This will format every `.py` file under `src/python/myproject`, except for `ignore.py`
$ ./pants fmt 'src/python/myproject/**/*.py' '!src/python/myproject/ignore.py'

You may use the --spec-file option to pass a text file with a list of all the files you'd like Pants to operate on (with a newline separating each file):

$ echo 'src/python/myproject/f1.py
  src/python/myproject/f2.py
  src/python/myproject/example/*.py' > to_be_formatted.txt
$ ./pants --spec-file=to_be_formatted.txt fmt
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