Crate 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 on the struct itself. For a more detailed description and examples, check out the Builder or click on the attribute.

Builder Configuration

Attributes that affect the generated struct and other items

Attribute	Description	Usage
kind	Set the sub-pattern 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
visibility	Change the visibility of the created builder (defaults to the same visibility as the struct)	visibility = pub(crate)
crate	Override the name of the crate when expanding macros (defaults to bauer)	crate = bauer_renamed
error	Set details about the generated error enum (attributes, doc, rename, force)	error(...)
build_fn	Set details about the build function (attributes, doc, rename, map)	build_fn(...)
builder_fn	Set details about the builder function added to the struct (attributes, doc, rename)	builder_fn(...)
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>)

Field Configuration

Attributes affect all functions generated the fields in this struct

Attribute	Description	Usage
prefix/suffix	Add a prefix/suffix to all field functions created for this builder	prefix = "set_" or suffix = "_field"
on	Apply field attributes to fields that match a specific type pattern	on(<type> => <attributes ...>)

Field Attributes

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

Special Field Treatment

Attributes that affect how a field is treated by the builder

Attribute	Description	Usage
associated	Mark this field as associated data with the builder. Associated fields are specified by the builder_fn.	associated
skip	Skip this field in the builder and construct its value using the other fields (or default value)	skip or skip = <value>

Field Configuration

Attributes that affect how fields are presented to the user

Attribute	Description	Usage
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
visibility	Change visibility of the generated function (defaults to the same visibility as the builder)	visibility = pub(crate)
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>)

Type Configuration

Configure how the field’s type is constructed or specified by the user

Attribute	Description	Usage
adapter	Fully customise how functions take arguments and convert them into the field value	adapter = |<arg>: <ty>| <expr>
default	Specify a default value or use Default	default or default = <value>
required	Make an Option field required to be specified as Some(value) or None	required
flag	Mark a boolean field as a flag, meaning that the if the function is called, the field will be marked true	flag
into	Make functions accept impl Into<Field>	into
tuple	Make functions accept tuple items as separate arguments	tuple or tuple(x, y)
repeat	Allow repeating call to add items to a structure	repeat or repeat = <type>
repeat_n	Control 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>

Modules

stateDeprecated

Derive Macros

Builder

The main macro