Module struct_enum_dispatch 

Dispatch #[miniextendr] on structs and enums to the appropriate derive helpers.

This module handles #[miniextendr] when applied to structs or enums (not functions, impl blocks, or traits). It dispatches to the correct derive helper based on:

• Field count (1-field → ALTREP by default, multi-field → ExternalPtr by default)
• Explicit mode attributes (list, dataframe, externalptr, match_arg, factor)
• Preference markers (prefer = "...")

Disambiguation table

Syntax	Result
#[miniextendr] on 1-field struct	ALTREP (backwards compat)
#[miniextendr(externalptr)] on 1-field struct	ExternalPtr
#[miniextendr(list)] on 1-field struct	List conversion
#[miniextendr(class = "...", base = "...")] on 1-field struct	ALTREP (explicit)
#[miniextendr] on multi-field struct	ExternalPtr
#[miniextendr(list)] on multi-field struct	IntoList + TryFromList + PreferList
#[miniextendr(dataframe)] on multi-field struct	DataFrameRow + PreferDataFrame
#[miniextendr(prefer = "...")] on struct	Prefer* marker
#[miniextendr] on fieldless enum	RFactor
#[miniextendr(match_arg)] on fieldless enum	MatchArg

Structs

StructEnumAttrs 🔒

Parsed attributes for #[miniextendr] on structs/enums.

Functions

expand_enum 🔒

Dispatches #[miniextendr] on a fieldless enum to the correct derive path.

expand_struct 🔒

Dispatches #[miniextendr] on a struct to the correct derive path.

expand_struct_or_enum

Main dispatch entry point for #[miniextendr] on a struct or enum.

field_count 🔒

Returns the number of fields on a struct (named, unnamed, or unit).

is_fieldless_enum 🔒

Returns true if every variant of the enum is a unit variant (no fields).

parse_attrs 🔒

Parses the attribute arguments of #[miniextendr(...)] when applied to a struct or enum.

strip_miniextendr_attrs 🔒

Strip #[miniextendr(...)] attributes from a DeriveInput.