---
name: mro
runtime: pp
source: src/native/mro/pp.rs
---
```{index} single: mro; Perl module (pp runtime)
```

# mro

MRO (Method Resolution Order) implementation

Provides DFS and C3 linearization of class hierarchies, matching
the behaviour of perl5's `mro` core module (mro.xs).

Public API:
- `get_linear_isa(class [, "dfs"|"c3"])` — recursive linearization
- `set_mro(class, "dfs"|"c3")` — per-class MRO preference
- `get_mro(class)` — return stored preference (default "dfs")
- `get_isarev(class)` — reverse @ISA index (computed on-the-fly)
- `get_pkg_gen(class)` — generation counter (per-package, real tracking)
- `is_universal(class)` — true only for "UNIVERSAL"
- `method_changed_in` / `invalidate_all_method_caches` — cache invalidation

Perl equivalent: mro (XS core module)

# Functions

## get_linear_isa
Returns the linearized @ISA for a class using DFS (default) or C3 algorithm.

    use mro;
    my $isa = mro::get_linear_isa('MyClass');        # DFS
    my $isa = mro::get_linear_isa('MyClass', 'c3');  # C3

## set_mro
Sets the MRO algorithm for a class. Valid values: `"dfs"`, `"c3"`.

    use mro;
    mro::set_mro('MyClass', 'c3');

## get_mro
Returns the stored MRO algorithm name for a class (defaults to `"dfs"`).

    use mro;
    my $type = mro::get_mro('MyClass');  # "dfs" or "c3"

## get_isarev
Returns an arrayref of classes that directly or indirectly inherit from
the given class (reverse @ISA index, computed on the fly).

    use mro;
    my $subclasses = mro::get_isarev('BaseClass');

## get_pkg_gen
Returns the per-package generation counter. Bumped on each `define_sub`
or `method_changed_in` call. Returns 0 for non-existent packages, 1 for
packages with no explicit counter yet.

    use mro;
    my $gen = mro::get_pkg_gen('MyClass');

## is_universal
Returns true only if the given class is `"UNIVERSAL"`.

    use mro;
    my $ok = mro::is_universal('UNIVERSAL');  # 1

## method_changed_in
Bumps the generation counter for the given class and invalidates all
CV caches. Call when method resolution may have changed.

    use mro;
    mro::method_changed_in('MyClass');

## invalidate_all_method_caches
Clears the entire CV cache without targeting a specific class.

    use mro;
    mro::invalidate_all_method_caches();

## import
Called implicitly by `use mro 'c3'`. Sets the MRO algorithm for the
calling package.

    use mro 'c3';  # sets C3 for current package