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Methods available in all Bazel files, including .bzl files, BUILD, MODULE.bazel, and WORKSPACE.

Members

abs

unknown abs(x)

Returns the absolute value of a number (a non-negative number with the same magnitude).
abs(-2.3) == 2.3

Parameters

Parameter Description
x int; or float; required
A number (int or float)

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.

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.

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 is False
The variable to convert.

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 is []
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 is 0
start index.

fail

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

Causes execution to fail with an error.

Parameters

Parameter Description
msg default is None
Deprecated: use positional arguments instead. This argument acts like an implicit leading positional argument.
attr string; or None; default is None
Deprecated. Causes an optional prefix containing this string to be added to the error message.
args required
A list of values, formatted with debugPrint (which is equivalent to str by default) 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 is 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 is 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 is 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 is []
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 is " "
The separator string between the objects, default is space (" ").
args required
The objects to print.

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 is 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 is 1
The increment (default is 1). It may be negative.

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.

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 is None
An optional function applied to each element before comparison.
reverse default is 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 is ()
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.

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.