123 lines
3.8 KiB
Markdown
123 lines
3.8 KiB
Markdown
# Skylib
|
|
|
|
[](https://buildkite.com/bazel/bazel-skylib)
|
|
|
|
Skylib is a standard library that provides functions useful for manipulating
|
|
collections, file paths, and other features that are useful when writing custom
|
|
build rules in Bazel.
|
|
|
|
> This library is currently under early development. Be aware that the APIs
|
|
> in these modules may change during this time.
|
|
|
|
Each of the `.bzl` files in the `lib` directory defines a "module"—a
|
|
`struct` that contains a set of related functions and/or other symbols that can
|
|
be loaded as a single unit, for convenience.
|
|
|
|
Skylib also provides build rules under the `rules` directory.
|
|
|
|
## Getting Started
|
|
|
|
### `WORKSPACE` file
|
|
|
|
Add the following to your `WORKSPACE` file to import the Skylib repository into
|
|
your workspace. Replace the version number in the `tag` attribute with the
|
|
version you wish to depend on:
|
|
|
|
```python
|
|
# bazel-skylb 0.8.0 released 2019.03.20 (https://github.com/bazelbuild/bazel-skylib/releases/tag/0.8.0)
|
|
skylib_version = "0.8.0"
|
|
http_archive(
|
|
name = "bazel_skylib",
|
|
type = "tar.gz",
|
|
url = "https://github.com/bazelbuild/bazel-skylib/releases/download/{}/bazel-skylib.{}.tar.gz".format (skylib_version, skylib_version),
|
|
sha256 = "2ef429f5d7ce7111263289644d233707dba35e39696377ebab8b0bc701f7818e",
|
|
)
|
|
```
|
|
|
|
If you want to use `lib/unittest.bzl` from Skylib versions released in or after
|
|
December 2018, then you also should add to the `WORKSPACE` file:
|
|
|
|
```python
|
|
load("@bazel_skylib//:workspace.bzl", "bazel_skylib_workspace")
|
|
|
|
bazel_skylib_workspace()
|
|
```
|
|
|
|
### `BUILD` and `*.bzl` files
|
|
|
|
Then, in the `BUILD` and/or `*.bzl` files in your own workspace, you can load
|
|
the modules (listed [below](#list-of-modules)) and access the symbols by
|
|
dotting into those structs:
|
|
|
|
```python
|
|
load("@bazel_skylib//lib:paths.bzl", "paths")
|
|
load("@bazel_skylib//lib:shell.bzl", "shell")
|
|
|
|
p = paths.basename("foo.bar")
|
|
s = shell.quote(p)
|
|
```
|
|
|
|
## List of modules (in lib/)
|
|
|
|
* [collections](docs/collections_doc.md)
|
|
* [dicts](docs/dicts_doc.md)
|
|
* [partial](docs/partial_doc.md)
|
|
* [paths](docs/paths_doc.md)
|
|
* [selects](docs/selects_doc.md)
|
|
* [sets](lib/sets.bzl) - _deprecated_, use `new_sets`
|
|
* [new_sets](docs/new_sets_doc.md)
|
|
* [shell](docs/shell_doc.md)
|
|
* [structs](docs/structs_doc.md)
|
|
* [types](docs/types_doc.md)
|
|
* [unittest](docs/unittest_doc.md)
|
|
* [versions](docs/versions_doc.md)
|
|
|
|
## List of rules (in rules/)
|
|
|
|
* [analysis_test](docs/analysis_test_doc.md)
|
|
* [build_test](docs/build_test_doc.md)
|
|
* [`cmd_maprule` and `bash_maprule`](docs/maprule_doc.md)
|
|
|
|
## Writing a new module
|
|
|
|
Steps to add a module to Skylib:
|
|
|
|
1. Create a new `.bzl` file in the `lib` directory.
|
|
|
|
1. Write the functions or other symbols (such as constants) in that file,
|
|
defining them privately (prefixed by an underscore).
|
|
|
|
1. Create the exported module struct, mapping the public names of the symbols
|
|
to their implementations. For example, if your module was named `things` and
|
|
had a function named `manipulate`, your `things.bzl` file would look like
|
|
this:
|
|
|
|
```python
|
|
def _manipulate():
|
|
...
|
|
|
|
things = struct(
|
|
manipulate=_manipulate,
|
|
)
|
|
```
|
|
|
|
1. Add unit tests for your module in the `tests` directory.
|
|
|
|
## `bzl_library`
|
|
|
|
The `bzl_library.bzl` rule can be used to aggregate a set of
|
|
Starlark files and its dependencies for use in test targets and
|
|
documentation generation.
|
|
|
|
## Troubleshooting
|
|
|
|
If you try to use `unittest` and you get the following error:
|
|
|
|
```
|
|
ERROR: While resolving toolchains for target //foo:bar: no matching toolchains found for types @bazel_skylib//toolchains:toolchain_type
|
|
ERROR: Analysis of target '//foo:bar' failed; build aborted: no matching toolchains found for types @bazel_skylib//toolchains:toolchain_type
|
|
```
|
|
|
|
then you probably forgot to load and call `bazel_skylib_workspace()` in your
|
|
`WORKSPACE` file.
|