Globals

Objects, functions and modules registered in the global environment.

Members

all
analysis_test_transition
any
aspect
bind
bool
configuration_field
depset
dict
dir
enumerate
exec_group
fail
float
getattr
hasattr
hash
int
len
list
max
min
print
provider
range
register_execution_platforms
register_toolchains
repository_rule
repr
reversed
rule
select
sorted
str
tuple
type
workspace
zip

all

bool all(elements)

Returns true if all elements evaluate to True or if the collection is empty. Elements are converted to boolean using the bool function.

all(["hello", 3, True]) == True
all([-1, 0, 1]) == False

Parameters

Parameter	Description
`elements`	; required A string or a collection of elements.

analysis_test_transition

transition analysis_test_transition(settings)

Creates a configuration transition to be applied on an analysis-test rule's dependencies. This transition may only be applied on attributes of rules with analysis_test = True. Such rules are restricted in capabilities (for example, the size of their dependency tree is limited), so transitions created using this function are limited in potential scope as compared to transitions created using transition.

This function is primarily designed to facilitate the Analysis Test Framework core library. See its documentation (or its implementation) for best practices.

Parameters

Parameter	Description
`settings`	; required A dictionary containing information about configuration settings which should be set by this configuration transition. Keys are build setting labels and values are their new post-transition values. All other settings are unchanged. Use this to declare specific configuration settings that an analysis test requires to be set in order to pass.

any

bool any(elements)

Returns true if at least one element evaluates to True. Elements are converted to boolean using the bool function.

any([-1, 0, 1]) == True
any([False, 0, ""]) == False

Parameters

Parameter	Description
`elements`	; required A string or a collection of elements.

aspect

Aspect aspect(implementation, attr_aspects=[], attrs=None, required_aspect_providers=[], provides=[], fragments=[], host_fragments=[], toolchains=[], incompatible_use_toolchain_transition=False, doc='', *, apply_to_generating_rules=False)

Creates a new aspect. The result of this function must be stored in a global value. Please see the introduction to Aspects for more details.

Parameters

Parameter	Description
`implementation`	; required A Starlark function that implements this aspect, with exactly two parameters: Target (the target to which the aspect is applied) and ctx (the rule context which the targetis created from). Attributes of the target are available via the `ctx.rule` field. This function is evaluated during the analysis phase for each application of an aspect to a target.
`attr_aspects`	`sequence of strings`; default = [] List of attribute names. The aspect propagates along dependencies specified in the attributes of a target with these names. Common values here include `deps` and `exports`. The list can also contain a single string `"*"` to propagate along all dependencies of a target.
`attrs`	`dict; or None`; default = None A dictionary declaring all the attributes of the aspect. It maps from an attribute name to an attribute object, like `attr.label` or `attr.string` (see attr module). Aspect attributes are available to implementation function as fields of `ctx` parameter. Implicit attributes starting with `_` must have default values, and have type `label` or `label_list`. Explicit attributes must have type `string`, and must use the `values` restriction. Explicit attributes restrict the aspect to only be used with rules that have attributes of the same name, type, and valid values according to the restriction.
`required_aspect_providers`	; default = [] This attribute allows this aspect to inspect other aspects. The value must be a list of providers, or a list of lists of providers. For example, `[FooInfo, BarInfo, [BazInfo, QuxInfo]]` is a valid value. A single list of providers will automatically be converted to a list containing one list of providers. That is, `[FooInfo, BarInfo]` will automatically be converted to `[[FooInfo, BarInfo]]`. To make another aspect (e.g. `other_aspect`) visible to this aspect, `other_aspect` must provide all providers from at least one of the lists. In the example of `[FooInfo, BarInfo, [BazInfo, QuxInfo]]`, this aspect can only see `other_aspect` if and only if `other_aspect` provides `FooInfo` or `BarInfo` or both `BazInfo` and `QuxInfo`.
`provides`	; default = [] A list of providers that the implementation function must return. It is an error if the implementation function omits any of the types of providers listed here from its return value. However, the implementation function may return additional providers not listed here. Each element of the list is an `*Info` object returned by `provider()`, except that a legacy provider is represented by its string name instead.
`fragments`	`sequence of strings`; default = [] List of names of configuration fragments that the aspect requires in target configuration.
`host_fragments`	`sequence of strings`; default = [] List of names of configuration fragments that the aspect requires in host configuration.
`toolchains`	`sequence of strings`; default = [] If set, the set of toolchains this rule requires. Toolchains will be found by checking the current platform, and provided to the rule implementation via `ctx.toolchain`.
`incompatible_use_toolchain_transition`	; default = False If set, this aspect will use the toolchain transition for toolchain dependencies. This is ignored if the --incompatible_use_toolchain_transition flag is set.
`doc`	; default = '' A description of the aspect that can be extracted by documentation generating tools.
`apply_to_generating_rules`	; default = False If true, the aspect will, when applied to an output file, instead apply to the output file's generating rule. For example, suppose an aspect propagates transitively through attribute `deps` and it is applied to target `alpha`. Suppose `alpha` has `deps = [':beta_output']`, where `beta_output` is a declared output of a target `beta`. Suppose `beta` has a target `charlie` as one of its `deps`. If `apply_to_generating_rules=True` for the aspect, then the aspect will propagate through `alpha`, `beta`, and `charlie`. If False, then the aspect will propagate only to `alpha`. False by default.

bind

None bind(name, actual=None)

Warning: use of bind() is not recommended. See Consider removing bind for a long discussion if its issues and alternatives.

Gives a target an alias in the //external package.

Parameters

Parameter	Description
`name`	; required The label under '//external' to serve as the alias name
`actual`	`string; or None`; default = None The real label to be aliased

bool

bool bool(x=False)

Constructor for the bool type. It returns False if the object is None, False, an empty string (""), the number 0, or an empty collection (e.g. (), []). Otherwise, it returns True.

Parameters

Parameter	Description
`x`	; default = False The variable to convert.

configuration_field

LateBoundDefault configuration_field(fragment, name)

References a late-bound default value for an attribute of type label. A value is 'late-bound' if it requires the configuration to be built before determining the value. Any attribute using this as a value must be private.

Example usage:

Defining a rule attribute:

'_foo': attr.label(default=configuration_field(fragment='java', name='toolchain'))

Accessing in rule implementation:

  def _rule_impl(ctx):
    foo_info = ctx.attr._foo
    ...

Parameters

Parameter	Description
`fragment`	; required The name of a configuration fragment which contains the late-bound value.
`name`	; required The name of the value to obtain from the configuration fragment.

depset

depset depset(x=None, order="default", *, direct=None, transitive=None, items=[])

Creates a depset. The direct parameter is a list of direct elements of the depset, and transitive parameter is a list of depsets whose elements become indirect elements of the created depset. The order in which elements are returned when the depset is converted to a list is specified by the order parameter. See the Depsets overview for more information.

All elements (direct and indirect) of a depset must be of the same type, as obtained by the expression type(x).

Because a hash-based set is used to eliminate duplicates during iteration, all elements of a depset should be hashable. However, this invariant is not currently checked consistently in all constructors. Use the --incompatible_always_check_depset_elements flag to enable consistent checking; this will be the default behavior in future releases; see Issue 10313.

In addition, elements must currently be immutable, though this restriction will be relaxed in future.

The order of the created depset should be compatible with the order of its transitive depsets. "default" order is compatible with any other order, all other orders are only compatible with themselves.

Note on backward/forward compatibility. This function currently accepts a positional items parameter. It is deprecated and will be removed in the future, and after its removal direct will become a sole positional parameter of the depset function. Thus, both of the following calls are equivalent and future-proof:

depset(['a', 'b'], transitive = [...])
depset(direct = ['a', 'b'], transitive = [...])

Parameters

Parameter	Description
`x`	; default = None A positional parameter distinct from other parameters for legacy support. If `--incompatible_disable_depset_items` is false, this parameter serves as the value of `items`. If `--incompatible_disable_depset_items` is true, this parameter serves as the value of `direct`. See the documentation for these parameters for more details.
`order`	; default = "default" The traversal strategy for the new depset. See here for the possible values.
`direct`	; default = None A list of direct elements of a depset.
`transitive`	`sequence of depsets; or None`; default = None A list of depsets whose elements will become indirect elements of the depset.
`items`	; default = [] Deprecated. This parameter is deprecated and will be removed soon. Please do not depend on it. It is disabled with `---incompatible_disable_depset_items`. Use this flag to verify your code is compatible with its imminent removal. Deprecated: Either an iterable whose items become the direct elements of the new depset, in left-to-right order, or else a depset that becomes a transitive element of the new depset. In the latter case, `transitive` cannot be specified.

dict

dict dict(pairs=[], **kwargs)

Creates a dictionary from an optional positional argument and an optional set of keyword arguments. In the case where the same key is given multiple times, the last value will be used. Entries supplied via keyword arguments are considered to come after entries supplied via the positional argument.

Parameters

Parameter	Description
`pairs`	; default = [] A dict, or an iterable whose elements are each of length 2 (key, value).
`kwargs`	; required Dictionary of additional entries.

dir

list dir(x)

Returns a list of strings: the names of the attributes and methods of the parameter object.

Parameters

Parameter	Description
`x`	; required The object to check.

enumerate

list enumerate(list, start=0)

Returns a list of pairs (two-element tuples), with the index (int) and the item from the input sequence.

enumerate([24, 21, 84]) == [(0, 24), (1, 21), (2, 84)]

Parameters

Parameter	Description
`list`	; required input sequence.
`start`	; default = 0 start index.

exec_group

exec_group exec_group(toolchains=[], exec_compatible_with=[], copy_from_rule=False)

experimental Creates an execution group which can be used to create actions for a specific execution platform during rule implementation.

Parameters

Parameter	Description
`toolchains`	`sequence of strings`; default = [] Experimental The set of toolchains this execution group requires.
`exec_compatible_with`	`sequence of strings`; default = [] Experimental A list of constraints on the execution platform.
`copy_from_rule`	; default = False Experimental If set to true, this exec group inherits the toolchains and constraints of the rule to which this group is attached. If set to any other string this will throw an error.

fail

None fail(msg=None, attr=None, *args)

Causes execution to fail with an error.

Parameters

Parameter	Description
`msg`	; default = None Deprecated: use positional arguments instead. This argument acts like an implicit leading positional argument.
`attr`	`string; or None`; default = None Deprecated. Causes an optional prefix containing this string to be added to the error message.
`args`	; required A list of values, formatted with str and joined with spaces, that appear in the error message.

float

float float(x=unbound)

Returns x as a float value.

If x is already a float, float returns it unchanged.
If x is a bool, float returns 1.0 for True and 0.0 for False.
If x is an int, float returns the nearest finite floating-point value to x, or an error if the magnitude is too large.
If x is a string, it must be a valid floating-point literal, or be equal (ignoring case) to NaN, Inf, or Infinity, optionally preceded by a + or - sign.

Any other value causes an error. With no argument, float() returns 0.0.

Parameters

Parameter	Description
`x`	; default = unbound The value to convert.

getattr

unknown getattr(x, name, default=unbound)

Returns the struct's field of the given name if it exists. If not, it either returns default (if specified) or raises an error. getattr(x, "foobar") is equivalent to x.foobar.

getattr(ctx.attr, "myattr")
getattr(ctx.attr, "myattr", "mydefault")

Parameters

Parameter	Description
`x`	; required The struct whose attribute is accessed.
`name`	; required The name of the struct attribute.
`default`	; default = unbound The default value to return in case the struct doesn't have an attribute of the given name.

hasattr

bool hasattr(x, name)

Returns True if the object x has an attribute or method of the given name, otherwise False. Example:

hasattr(ctx.attr, "myattr")

Parameters

Parameter	Description
`x`	; required The object to check.
`name`	; required The name of the attribute.

hash

int hash(value)

Return a hash value for a string. This is computed deterministically using the same algorithm as Java's String.hashCode(), namely:

s[0] * (31^(n-1)) + s[1] * (31^(n-2)) + ... + s[n-1]

Hashing of values besides strings is not currently supported.

Parameters

Parameter	Description
`value`	; required String value to hash.

int

int int(x, base=unbound)

Returns x as an int value.

If x is already an int, int returns it unchanged.
If x is a bool, int returns 1 for True and 0 for False.
If x is a string, it must have the format <sign><prefix><digits>. <sign> is either "+", "-", or empty (interpreted as positive). <digits> are a sequence of digits from 0 up to base - 1, where the letters a-z (or equivalently, A-Z) are used as digits for 10-35. In the case where base is 2/8/16, <prefix> is optional and may be 0b/0o/0x (or equivalently, 0B/0O/0X) respectively; if the base is any other value besides these bases or the special value 0, the prefix must be empty. In the case where base is 0, the string is interpreted as an integer literal, in the sense that one of the bases 2/8/10/16 is chosen depending on which prefix if any is used. If base is 0, no prefix is used, and there is more than one digit, the leading digit cannot be 0; this is to avoid confusion between octal and decimal. The magnitude of the number represented by the string must be within the allowed range for the int type.
If x is a float, int returns the integer value of the float, rounding towards zero. It is an error if x is non-finite (NaN or infinity).

This function fails if x is any other type, or if the value is a string not satisfying the above format. Unlike Python's int function, this function does not allow zero arguments, and does not allow extraneous whitespace for string arguments.

Examples:

int("123") == 123
int("-123") == -123
int("+123") == 123
int("FF", 16) == 255
int("0xFF", 16) == 255
int("10", 0) == 10
int("-0x10", 0) == -16
int("-0x10", 0) == -16
int("123.456") == 123

Parameters

Parameter	Description
`x`	; required The string to convert.
`base`	; default = unbound The base used to interpret a string value; defaults to 10. Must be between 2 and 36 (inclusive), or 0 to detect the base as if `x` were an integer literal. This parameter must not be supplied if the value is not a string.

len

int len(x)

Returns the length of a string, sequence (such as a list or tuple), dict, or other iterable.

Parameters

Parameter	Description
`x`	; required The value whose length to report.

list

list list(x=[])

Returns a new list with the same elements as the given iterable value.

list([1, 2]) == [1, 2]
list((2, 3, 2)) == [2, 3, 2]
list({5: "a", 2: "b", 4: "c"}) == [5, 2, 4]

Parameters

Parameter	Description
`x`	; default = [] The object to convert.

max

unknown max(*args)

Returns the largest one of all given arguments. If only one argument is provided, it must be a non-empty iterable.It is an error if elements are not comparable (for example int with string), or if no arguments are given.

max(2, 5, 4) == 5
max([5, 6, 3]) == 6

Parameters

Parameter	Description
`args`	; required The elements to be checked.

min

unknown min(*args)

Returns the smallest one of all given arguments. If only one argument is provided, it must be a non-empty iterable. It is an error if elements are not comparable (for example int with string), or if no arguments are given.

min(2, 5, 4) == 2
min([5, 6, 3]) == 3

Parameters

Parameter	Description
`args`	; required The elements to be checked.

print

None print(sep=" ", *args)

Prints args as debug output. It will be prefixed with the string "DEBUG" and the location (file and line number) of this call. The exact way in which the arguments are converted to strings is unspecified and may change at any time. In particular, it may be different from (and more detailed than) the formatting done by str() and repr().

Using print in production code is discouraged due to the spam it creates for users. For deprecations, prefer a hard error using fail() whenever possible.

Parameters

Parameter	Description
`sep`	; default = " " The separator string between the objects, default is space (" ").
`args`	; required The objects to print.

provider

Provider provider(doc='', *, fields=None)

Creates a declared provider 'constructor'. The return value of this function can be used to create "struct-like" values. Example:

data = provider()
d = data(x = 2, y = 3)
print(d.x + d.y) # prints 5

See Rules (Providers) for a comprehensive guide on how to use providers.

Parameters

Parameter	Description
`doc`	; default = '' A description of the provider that can be extracted by documentation generating tools.
`fields`	`sequence of strings; or dict; or None`; default = None If specified, restricts the set of allowed fields. Possible values are: list of fields: provider(fields = ['a', 'b']) dictionary field name -> documentation: provider( fields = { 'a' : 'Documentation for a', 'b' : 'Documentation for b' }) All fields are optional.

range

sequence range(start_or_stop, stop_or_none=None, step=1)

Creates a list where items go from start to stop, using a step increment. If a single argument is provided, items will range from 0 to that element.

range(4) == [0, 1, 2, 3]
range(3, 9, 2) == [3, 5, 7]
range(3, 0, -1) == [3, 2, 1]

Parameters

Parameter	Description
`start_or_stop`	; required Value of the start element if stop is provided, otherwise value of stop and the actual start is 0
`stop_or_none`	`int; or None`; default = None optional index of the first item not to be included in the resulting list; generation of the list stops before `stop` is reached.
`step`	; default = 1 The increment (default is 1). It may be negative.

register_execution_platforms

None register_execution_platforms(*platform_labels)

Parameters

Parameter	Description
`platform_labels`	`sequence of strings`; required The labels of the platforms to register.

register_toolchains

None register_toolchains(*toolchain_labels)

Register an already-defined toolchain so that Bazel can use it during toolchain resolution. See examples of defining and registering toolchains.

Parameters

Parameter	Description
`toolchain_labels`	`sequence of strings`; required The labels of the toolchains to register.

repository_rule

callable repository_rule(implementation, *, attrs=None, local=False, environ=[], configure=False, remotable=False, doc='')

Creates a new repository rule. Store it in a global value, so that it can be loaded and called from the WORKSPACE file.

Parameters

Parameter	Description
`implementation`	; required the function that implements this rule. Must have a single parameter, `repository_ctx`. The function is called during the loading phase for each instance of the rule.
`attrs`	`dict; or None`; default = None dictionary to declare all the attributes of the rule. It maps from an attribute name to an attribute object (see attr module). Attributes starting with `_` are private, and can be used to add an implicit dependency on a label to a file (a repository rule cannot depend on a generated artifact). The attribute `name` is implicitly added and must not be specified.
`local`	; default = False Indicate that this rule fetches everything from the local system and should be reevaluated at every fetch.
`environ`	`sequence of strings`; default = [] Provides a list of environment variable that this repository rule depends on. If an environment variable in that list change, the repository will be refetched.
`configure`	; default = False Indicate that the repository inspects the system for configuration purpose
`remotable`	; default = False Experimental. This parameter is experimental and may change at any time. Please do not depend on it. It may be enabled on an experimental basis by setting `---experimental_repo_remote_exec` Compatible with remote execution
`doc`	; default = '' A description of the repository rule that can be extracted by documentation generating tools.

repr

string repr(x)

Converts any object to a string representation. This is useful for debugging.

repr("ab") == '"ab"'

Parameters

Parameter	Description
`x`	; required The object to convert.

reversed

list reversed(sequence)

Returns a new, unfrozen list that contains the elements of the original iterable sequence in reversed order.

reversed([3, 5, 4]) == [4, 5, 3]

Parameters

Parameter	Description
`sequence`	; required The iterable sequence (e.g. list) to be reversed.

rule

callable rule(implementation, test=False, attrs=None, outputs=None, executable=False, output_to_genfiles=False, fragments=[], host_fragments=[], _skylark_testable=False, toolchains=[], incompatible_use_toolchain_transition=False, doc='', *, provides=[], exec_compatible_with=[], analysis_test=False, build_setting=None, cfg=None, exec_groups=None)

Creates a new rule, which can be called from a BUILD file or a macro to create targets.

Rules must be assigned to global variables in a .bzl file; the name of the global variable is the rule's name.

Test rules are required to have a name ending in _test, while all other rules must not have this suffix. (This restriction applies only to rules, not to their targets.)

Parameters

Parameter	Description
`implementation`	; required the Starlark function implementing this rule, must have exactly one parameter: ctx. The function is called during the analysis phase for each instance of the rule. It can access the attributes provided by the user. It must create actions to generate all the declared outputs.
`test`	; default = False Whether this rule is a test rule, that is, whether it may be the subject of a `bazel test` command. All test rules are automatically considered executable; it is unnecessary (and discouraged) to explicitly set `executable = True` for a test rule. See the Rules page for more information.
`attrs`	`dict; or None`; default = None dictionary to declare all the attributes of the rule. It maps from an attribute name to an attribute object (see attr module). Attributes starting with `_` are private, and can be used to add an implicit dependency on a label. The attribute `name` is implicitly added and must not be specified. Attributes `visibility`, `deprecation`, `tags`, `testonly`, and `features` are implicitly added and cannot be overridden. Most rules need only a handful of attributes. To limit memory usage, the rule function imposes a cap on the size of attrs.
`outputs`	`dict; or None; or function`; default = None Deprecated. This parameter is deprecated and will be removed soon. Please do not depend on it. It is disabled with `---incompatible_no_rule_outputs_param`. Use this flag to verify your code is compatible with its imminent removal. This parameter has been deprecated. Migrate rules to use `OutputGroupInfo` or `attr.output` instead. A schema for defining predeclared outputs. Unlike `output` and `output_list` attributes, the user does not specify the labels for these files. See the Rules page for more on predeclared outputs. The value of this argument is either a dictionary or a callback function that produces a dictionary. The callback works similar to computed dependency attributes: The function's parameter names are matched against the rule's attributes, so for example if you pass `outputs = _my_func` with the definition `def _my_func(srcs, deps): ...`, the function has access to the attributes `srcs` and `deps`. Whether the dictionary is specified directly or via a function, it is interpreted as follows. Each entry in the dictionary creates a predeclared output where the key is an identifier and the value is a string template that determines the output's label. In the rule's implementation function, the identifier becomes the field name used to access the output's `File` in `ctx.outputs`. The output's label has the same package as the rule, and the part after the package is produced by substituting each placeholder of the form `"%{ATTR}"` with a string formed from the value of the attribute `ATTR`: String-typed attributes are substituted verbatim. Label-typed attributes become the part of the label after the package, minus the file extension. For example, the label `"//pkg:a/b.c"` becomes `"a/b"`. Output-typed attributes become the part of the label after the package, including the file extension (for the above example, `"a/b.c"`). All list-typed attributes (for example, `attr.label_list`) used in placeholders are required to have exactly one element. Their conversion is the same as their non-list version (`attr.label`). Other attribute types may not appear in placeholders. The special non-attribute placeholders `%{dirname}` and `%{basename}` expand to those parts of the rule's label, excluding its package. For example, in `"//pkg:a/b.c"`, the dirname is `a` and the basename is `b.c`. In practice, the most common substitution placeholder is `"%{name}"`. For example, for a target named "foo", the outputs dict `{"bin": "%{name}.exe"}` predeclares an output named `foo.exe` that is accessible in the implementation function as `ctx.outputs.bin`.
`executable`	; default = False Whether this rule is considered executable, that is, whether it may be the subject of a `bazel run` command. See the Rules page for more information.
`output_to_genfiles`	; default = False If true, the files will be generated in the genfiles directory instead of the bin directory. Unless you need it for compatibility with existing rules (e.g. when generating header files for C++), do not set this flag.
`fragments`	`sequence of strings`; default = [] List of names of configuration fragments that the rule requires in target configuration.
`host_fragments`	`sequence of strings`; default = [] List of names of configuration fragments that the rule requires in host configuration.
`_skylark_testable`	; default = False (Experimental) If true, this rule will expose its actions for inspection by rules that depend on it via an Actions provider. The provider is also available to the rule itself by calling ctx.created_actions(). This should only be used for testing the analysis-time behavior of Starlark rules. This flag may be removed in the future.
`toolchains`	`sequence of strings`; default = [] If set, the set of toolchains this rule requires. Toolchains will be found by checking the current platform, and provided to the rule implementation via `ctx.toolchain`.
`incompatible_use_toolchain_transition`	; default = False If set, this rule will use the toolchain transition for toolchain dependencies. This is ignored if the --incompatible_use_toolchain_transition flag is set.
`doc`	; default = '' A description of the rule that can be extracted by documentation generating tools.
`provides`	; default = [] A list of providers that the implementation function must return. It is an error if the implementation function omits any of the types of providers listed here from its return value. However, the implementation function may return additional providers not listed here. Each element of the list is an `*Info` object returned by `provider()`, except that a legacy provider is represented by its string name instead.
`exec_compatible_with`	`sequence of strings`; default = [] A list of constraints on the execution platform that apply to all targets of this rule type.
`analysis_test`	; default = False If true, then this rule is treated as an analysis test. Note: Analysis test rules are primarily defined using infrastructure provided in core Starlark libraries. See Testing for guidance. If a rule is defined as an analysis test rule, it becomes allowed to use configuration transitions defined using analysis_test_transition on its attributes, but opts into some restrictions: Targets of this rule are limited in the number of transitive dependencies they may have. The rule is considered a test rule (as if `test=True` were set). This supercedes the value of `test` The rule implementation function may not register actions. Instead, it must register a pass/fail result via providing AnalysisTestResultInfo.
`build_setting`	`BuildSetting; or None`; default = None If set, describes what kind of `build setting` this rule is. See the `config` module. If this is set, a mandatory attribute named "build_setting_default" is automatically added to this rule, with a type corresponding to the value passed in here.
`cfg`	; default = None If set, points to the configuration transition the rule will apply to its own configuration before analysis.
`exec_groups`	`dict; or None`; default = None Experimental. This parameter is experimental and may change at any time. Please do not depend on it. It may be enabled on an experimental basis by setting `---experimental_exec_groups` Dict of execution group name (string) to `exec_group`s. If set, allows rules to run actions on multiple execution platforms within a single target. See execution groups documentation for more info.

select

unknown select(x, no_match_error='')

select() is the helper function that makes a rule attribute configurable. See build encyclopedia for details.

Parameters

Parameter	Description
`x`	; required A dict that maps configuration conditions to values. Each key is a label string that identifies a config_setting instance.
`no_match_error`	; default = '' Optional custom error to report if no condition matches.

sorted

list sorted(iterable, *, key=None, reverse=False)

Returns a new sorted list containing all the elements of the supplied iterable sequence. An error may occur if any pair of elements x, y may not be compared using x < y. The elements are sorted into ascending order, unless the reverse argument is True, in which case the order is descending. Sorting is stable: elements that compare equal retain their original relative order.

sorted([3, 5, 4]) == [3, 4, 5]

Parameters

Parameter	Description
`iterable`	; required The iterable sequence to sort.
`key`	; default = None An optional function applied to each element before comparison.
`reverse`	; default = False Return results in descending order.

str

string str(x)

Converts any object to string. This is useful for debugging.

str("ab") == "ab"
str(8) == "8"

Parameters

Parameter	Description
`x`	; required The object to convert.

tuple

tuple tuple(x=())

Returns a tuple with the same elements as the given iterable value.

tuple([1, 2]) == (1, 2)
tuple((2, 3, 2)) == (2, 3, 2)
tuple({5: "a", 2: "b", 4: "c"}) == (5, 2, 4)

Parameters

Parameter	Description
`x`	; default = () The object to convert.

type

string type(x)

Returns the type name of its argument. This is useful for debugging and type-checking. Examples:

type(2) == "int"
type([1]) == "list"
type(struct(a = 2)) == "struct"

This function might change in the future. To write Python-compatible code and be future-proof, use it only to compare return values:

if type(x) == type([]):  # if x is a list

Parameters

Parameter	Description
`x`	; required The object to check type of.

workspace

None workspace(name, managed_directories={})

This function can only be used in a WORKSPACE file and must be declared before all other functions in the WORKSPACE file. Each WORKSPACE file should have a workspace function.

Sets the name for this workspace. Workspace names should be a Java-package-style description of the project, using underscores as separators, e.g., github.com/bazelbuild/bazel should use com_github_bazelbuild_bazel.

This name is used for the directory that the repository's runfiles are stored in. For example, if there is a runfile foo/bar in the local repository and the WORKSPACE file contains workspace(name = 'baz'), then the runfile will be available under mytarget.runfiles/baz/foo/bar. If no workspace name is specified, then the runfile will be symlinked to bar.runfiles/foo/bar.

Remote repository rule names must be valid workspace names. For example, you could have maven_jar(name = 'foo'), but not maven_jar(name = 'foo.bar'), as Bazel would attempt to write a WORKSPACE file for the maven_jar containing workspace(name = 'foo.bar').

Parameters

Parameter	Description
`name`	; required the name of the workspace. Names must start with a letter and can only contain letters, numbers, and underscores.
`managed_directories`	; default = {} Dict (strings to list of strings) for defining the mappings between external repositories and relative (to the workspace root) paths to directories they incrementally update. Managed directories must be excluded from the source tree by listing them (or their parent directories) in the .bazelignore file.

zip

list zip(*args)

Returns a list of tuples, where the i-th tuple contains the i-th element from each of the argument sequences or iterables. The list has the size of the shortest input. With a single iterable argument, it returns a list of 1-tuples. With no arguments, it returns an empty list. Examples:

zip()  # == []
zip([1, 2])  # == [(1,), (2,)]
zip([1, 2], [3, 4])  # == [(1, 3), (2, 4)]
zip([1, 2], [3, 4, 5])  # == [(1, 3), (2, 4)]

Parameters

Parameter	Description
`args`	; required lists to zip.