# Module Unit_info

    module Unit_info: sig .. end

This module centralize the handling of compilation files and their metadata.

Maybe more importantly, this module provides functions for deriving module names from strings or filenames.

## Module name convention and computation

    type intf_or_impl =

`|` | `Intf`
`|` | `Impl`

    type modname = string

    type filename = string

    type file_prefix = string

    type error =

`|` | `Invalid_encoding of `filename``

    exception Error of error

    val modulize : string -> modname

`modulize s` capitalizes the first letter of `s`.

    val normalize : string -> string

`normalize s` uncapitalizes the first letter of `s`.

    val lax_modname_from_source : filename -> modname

`lax_modname_from_source filename` is `modulize stem` where `stem` is the basename of the filename `filename` stripped from all its extensions. For instance, `lax_modname_from_source "/pa.th/x.ml.pp"` is `"X"`.

    val strict_modname_from_source : filename -> modname

Same as `Unit_info.lax_modname_from_source` but raises an `Unit_info.error.Invalid_encoding` error on filename with invalid utf8 encoding.

### Module name validation function

    val is_unit_name : modname -> bool

`is_unit_name name` is true only if `name` can be used as a valid module name.

## Metadata for compilation unit

    type t

Metadata for a compilation unit:

- the module name associated to the unit
- the filename prefix (dirname + basename with all extensions stripped) for compilation artifacts
- the input source file For instance, when calling `ocamlopt dir/x.mli -o target/y.cmi`,
- the input source file is `dir/x.mli`
- the module name is `Y`
- the prefix is `target/y`

    val source_file : t -> filename

`source_file u` is the source file of `u`.

    val prefix : t -> file_prefix

`prefix u` is the filename prefix of the unit.

    val modname : t -> modname

`modname u` or `artifact_modname a` is the module name of the unit or compilation artifact.

    val kind : t -> intf_or_impl

`kind u` is the kind (interface or implementation) of the unit.

    val check_unit_name : t -> unit

`check_unit_name u` prints a warning if the derived module name `modname u` should not be used as a module name as specified by `Unit_info.is_unit_name``~strict:true`.

    val make : ?check_modname:bool ->
           source_file:filename ->
           intf_or_impl -> file_prefix -> t

`make ~check ~source_file kind prefix` associates both the `source_file` and the module name `Unit_info.lax_modname_from_source` `target_prefix` to the prefix filesystem path `prefix`.

If `check_modname=true`, this function emits a warning if the derived module name is not valid according to `Unit_info.check_unit_name`.

    module Artifact: sig .. end

Build artifacts

## Derived build artifact metadata

    val cmi : t -> Artifact.t

Those functions derive a specific `artifact` metadata from an `unit` metadata.

    val cmo : t -> Artifact.t

    val cmx : t -> Artifact.t

    val obj : t -> Artifact.t

    val cmt : t -> Artifact.t

    val cmti : t -> Artifact.t

    val annot : t -> Artifact.t

    val companion_obj : Artifact.t -> Artifact.t

The functions below change the type of an artifact by updating the extension of its filename. Those functions purposefully do not cover all artifact kinds because we want to track which artifacts are assumed to be bundled together.

    val companion_cmt : Artifact.t -> Artifact.t

    val companion_cmi : Artifact.t -> Artifact.t

Beware that `companion_cmi a` strips all extensions from the filename of `a` before adding the `".cmi"` suffix contrarily to the other functions which only remove the rightmost extension. In other words, the companion cmi of a file `something.d.cmo` is `something.cmi` and not `something.d.cmi`.

## Mli and cmi derived from implementation files

The compilation of module implementation changes in presence of mli and cmi files, the function belows help to handle this.

    val mli_from_source : t -> filename

`mli_from_source u` is the interface source filename associated to the unit `u`. The actual suffix depends on `Config.interface_suffix`.

    val mli_from_artifact : Artifact.t -> filename

`mli_from_artifact t` is the name of the interface source file derived from the artifact `t`. This variant is necessary when handling artifacts derived from an unknown source files (e.g. packed modules).

    val is_cmi : Artifact.t -> bool

Check if the artifact is a cmi

    val find_normalized_cmi : t -> Artifact.t

`find_normalized_cmi u` finds in the load_path a file matching the module name `modname u`.

- Raises `Not_found` if no such cmi exists