docs/versions/8.3.1/rules/lib/builtins/rule_attributes.mdx

---
title: 'rule\_attributes'
---

Information about attributes of a rule an aspect is applied to.

## Members

* [attr](#attr)
* [exec\_groups](#exec_groups)
* [executable](#executable)
* [file](#file)
* [files](#files)
* [kind](#kind)
* [toolchains](#toolchains)

## attr

```
struct rule_attributes.attr
```

A struct to access the values of the [attributes](https://bazel.build/versions/8.3.1/extending/rules#attributes). The values are provided by the user (if not, a default value is used). The attributes of the struct and the types of their values correspond to the keys and values of the [`attrs` dict](../globals/bzl#rule.attrs) provided to the [`rule` function](../globals/bzl#rule). [See example of use](https://github.com/bazelbuild/examples/blob/main/rules/attributes/printer.bzl).

## exec\_groups

```
ExecGroupCollection rule_attributes.exec_groups
```

A collection of the execution groups available for the rule the aspect is applied to, indexed by their names.

## executable

```
struct rule_attributes.executable
```

A `struct` containing executable files defined in [label type attributes](../toplevel/attr#label) marked as [`executable=True`](../toplevel/attr#label.executable). The struct fields correspond to the attribute names. Each value in the struct is either a [`File`](../builtins/File) or `None`. If an optional attribute is not specified in the rule then the corresponding struct value is `None`. If a label type is not marked as `executable=True`, no corresponding struct field is generated. [See example of use](https://github.com/bazelbuild/examples/blob/main/rules/actions_run/execute.bzl).

## file

```
struct rule_attributes.file
```

A `struct` containing files defined in [label type attributes](../toplevel/attr#label) marked as [`allow_single_file`](../toplevel/attr#label.allow_single_file). The struct fields correspond to the attribute names. The struct value is always a [`File`](../builtins/File) or `None`. If an optional attribute is not specified in the rule then the corresponding struct value is `None`. If a label type is not marked as `allow_single_file`, no corresponding struct field is generated. It is a shortcut for:

```
list(ctx.attr.<ATTR>.files)[0]
```

In other words, use `file` to access the (singular) [default output](https://bazel.build/versions/8.3.1/extending/rules#requesting_output_files) of a dependency. [See example of use](https://github.com/bazelbuild/examples/blob/main/rules/expand_template/hello.bzl).

## files

```
struct rule_attributes.files
```

A `struct` containing files defined in [label](../toplevel/attr#label) or [label list](../toplevel/attr#label_list) type attributes. The struct fields correspond to the attribute names. The struct values are `list` of [`File`](../builtins/File)s. It is a shortcut for:

```
[f for t in ctx.attr.<ATTR> for f in t.files]
```

In other words, use `files` to access the  [default outputs](https://bazel.build/versions/8.3.1/extending/rules#requesting_output_files) of a dependency. [See example of use](https://github.com/bazelbuild/examples/blob/main/rules/depsets/foo.bzl).

## kind

```
string rule_attributes.kind
```

The kind of a rule, such as 'cc\_library'

## toolchains

```
ToolchainContext rule_attributes.toolchains
```

Toolchains for the default exec group of the rule the aspect is applied to.