bauer

Bauer is a crate for automatically generating Builder-patterns for your structs!

Not sure what kind of builder you want? Bauer supports a variety of sub-patterns: Owned, Borrowed, and even Type-State!

Examples

#[derive(Builder)]
#[builder(kind = "type-state")]
pub struct Foo {
    required_field: u32,
    #[builder(default)]
    default_field: u32,
    #[builder(into)]
    converting_field: String,
    #[builder(repeat)]
    repeating_field: Vec<u32>,
    #[builder(repeat, repeat_n = 1..=3)]
    limited_repeating_field: Vec<u32>,
}

let foo: Foo = Foo::builder()
    .required_field(42)
    // .default_field(69) // defaults to 0
    .converting_field("hello world") // calls `.into()` to convert from &str -> String
    .repeating_field(420)
    .repeating_field(1337)
    .limited_repeating_field(0) // If not called 1..=3 times, this will fail
    .build();

Check out the repository for more examples!

Configuration

Kinds

Bauer supports generating 3 kinds of builders:

Owned (default) / Borrowed

"owned" builders are passed around by value and "borrowed" builders are passed by mutable reference.

Type-State

"type-state" builders use the type-state pattern and generate builds that are validated at compile-time using the type system.

Builder kinds can be switched between trivially using #[builder(kind = <kind>)] on the struct.

Builder Attributes

All of the attributes that may be applied to the builder are listed below. These go inside of a #[builder(..)] attribute. For a more detailed description and examples, check out the Builder or click on the attribute.

Attribute	Description	Usage
kind	Set the sub-patten to use for this builder	kind = "borrowed" or kind = "type-state"
const	Make this builder work at compile-time -- some limitations are added, but most features continue working	const
prefix/suffix	Add a prefix/suffix to all field functions created for this builder	prefix = "set_" or suffix = "_field"
visibility	Change the visibility of the created builder (defaults to the same visibility as the struct)	prefix = "set_" or suffix = "_field"
crate	Override the name of the crate when expanding macros (defaults to bauer)	prefix = "set_" or suffix = "_field"
attribute/attributes	Set attribute(s) on the generated builder struct	attribute(#[foo])
doc/docs	Set documentation items on the generated builder struct	doc(<doc strings>)
build_fn	Set details about the build function (attributes, doc, rename)	build_fn(...)
builder_fn	Set details about the builder function added to the struct (attributes, doc, rename)	builder_fn(...)
error	Set details about the generated error enum (attributes, doc, rename, force)	error(...)

Field Attributes

All of the attributes that may be applied to fields are listed below. These go inside of a #[builder(..)] attribute. For a more detailed description and examples, check out the Builder or click on the attribute.

Attribute	Description	Usage
skip	Skip this field in the builder. No other attributes may be specified when this is used.	skip or skip = <value>
default	Specify a default value or use Default	default or default = <value>
repeat	Allow repating call to add items to a structure	repeat or repeat = <type>
repeat_n	Contorl the number times a repeat field is allowed to be set. This controls the length of the final data	repeat_n = 1.. or repeat_n = 4
collector	Use a custom collector for converting into the target data structure (default: [FromIterator::from_iter])	collector = <function>
into	Make functions accept impl Into<Field>	into
tuple	Make functions accept tuple items as separate arguments	tuple or tuple(x, y)
adapter	Fully cusotmise how functions take arguments and convert them into the field value	adapter = |<arg>: <ty>| <expr>
rename	Rename the function that is generated for the field	rename = <name>
skip_prefix/skip_suffix	Skip using the prefix/suffix from the builder attribute	skip_prefix or skip_suffix
attribute/attributes	Set attribute(s) on the function generated for this field	attribute(#[foo])
doc/docs	Set documentation items on the function generated for this field	doc(<doc strings>)