# Module erl_tidy

- Function index
- Exported functions

## Description

Tidies Erlang source code, removing unused functions, updating obsolete constructs and function calls, etc.

Caveats: It is possible that in some intricate uses of macros, the automatic addition or removal of parentheses around uses or arguments could cause the resulting program to be rejected by the compiler; however, we have found no such case in existing code. Programs defining strange macros can usually not be read by this program, and in those cases, no changes will be made.

If you really, really want to, you may call it "Inga".

Disclaimer: The author accepts no responsibility for errors introduced in code that has been processed by the program. It has been reasonably well tested, but the possibility of errors remains. Keep backups of your original code safely stored, until you feel confident that the new, modified code can be trusted.

## Function Index

Exported Functions
dir/0 | See `dir/1`.
dir/1 | See `dir/2`.
dir/2 | Tidies Erlang source files in a directory and its subdirectories.
file/1 | See `file/2`.
file/2 | Tidies an Erlang source code file.
module/1 | See `module/2`.
module/2 | Tidies a syntax tree representation of a module definition.

## Exported Functions

### dir/0

`dir() -> ok`

Equivalent to `dir("")`.

### dir/1

`dir(Dir) -> ok`

Equivalent to `dir(Dir, [])`.

### dir/2

`dir(Directory::filename(), Options::[term()]) -> ok`

- filename() = file:filename()

Tidies Erlang source files in a directory and its subdirectories.

Available options:

{follow_links, bool()}
  If the value is `true`, symbolic directory links will be followed. The default value is `false`.
{recursive, bool()}
  If the value is `true`, subdirectories will be visited recursively. The default value is `true`.
{regexp, string()}
  The value denotes a regular expression (see module `regexp`). Tidying will only be applied to those regular files whose names match this pattern. The default value is `".*\\.erl$"`, which matches normal Erlang source file names.
{test, bool()}
  If the value is `true`, no files will be modified. The default value is `false`.
{verbose, bool()}
  If the value is `true`, progress messages will be output while the program is running, unless the `quiet` option is `true`. The default value when calling `dir/2` is `true`.

See the function `file/2` for further options.

See also: `regexp`, `file/2`.

### file/1

`file(Name) -> ok`

Equivalent to `file(Name, [])`.

### file/2

`file(Name::filename(), Options::[term()]) -> ok`

Tidies an Erlang source code file.

Available options are:

{backup_suffix, string()}
  Specifies the file name suffix to be used when a backup file is created; the default value is `".bak"` (cf. the `backups` option).
{backups, bool()}
  If the value is `true`, existing files will be renamed before new files are opened for writing. The new names are formed by appending the string given by the `backup_suffix` option to the original name. The default value is `true`.
{dir, filename()}
  Specifies the name of the directory in which the output file is to be written. By default, the current directory is used. If the value is an empty string, the current directory is used.
{outfile, filename()}
  Specifies the name of the file (without suffix) to which the resulting source code is to be written. If this option is not specified, the `Name` argument is used.
{printer, Function}
  - Function = (syntaxTree()) -> string()

  Specifies a function for prettyprinting Erlang syntax trees. This is used for outputting the resulting module definition, as well as for creating stub files. The function is assumed to return formatted text for the passed syntax tree, and should raise an exception if an error occurs. The default formatting function calls `erl_prettypr:format/2`.

{test, bool()}
  If the value is `true`, no files will be modified; this is typically most useful if the `verbose` flag is enabled, to generate reports about the program files without affecting them. The default value is `false`.

See the function `module/2` for further options.

See also: `module/2`, `erl_prettypr:format/2`.

### module/1

`module(Forms) -> syntaxTree()`

Equivalent to `module(Forms, [])`.

### module/2

`module(Forms, Options::[term()]) -> syntaxTree()`

- Forms = syntaxTree() | [syntaxTree()]
- syntaxTree() = erl_syntax:syntaxTree()

Tidies a syntax tree representation of a module definition. The given `Forms` may be either a single syntax tree of type `form_list`, or a list of syntax trees representing "program forms". In either case, `Forms` must represents a single complete module definition. The returned syntax tree has type `form_list` and represents a tidied-up version of the same source code.

Available options are:

{auto_export_vars, bool()}
  If the value is `true`, all matches "`{V1, ..., Vn} = E`" where `E` is a case-, if- or receive-expression whose branches all return n-tuples (or explicitly throw exceptions) will be rewritten to bind and export the variables `V1`, ..., `Vn` directly. The default value is `false`.

  For example:

                       {X, Y} = case ... of
                                    ... -> {17, foo()};
                                    ... -> {42, bar()}
                                end

  will be rewritten to:

                       case ... of
                           ... -> X = 17, Y = foo(), {X, Y};
                           ... -> X = 42, Y = bar(), {X, Y}
                       end

{file, string()}
  Specifies the name of the file from which the source code was taken. This is only used for generation of error reports. The default value is the empty string.
{keep_unused, bool()}
  If the value is `true`, unused functions will not be removed from the code. The default value is `false`.
{no_imports, bool()}
  If the value is `true`, all import statements will be removed and calls to imported functions will be expanded to explicit remote calls. The default value is `false`.
{old_guard_tests, bool()}
  If the value is `true`, guard tests will use the old names instead of the new ones, e.g. "`integer(X)`" instead of "`is_integer(X)`". The default value is `false`.
{quiet, bool()}
  If the value is `true`, all information messages and warning messages will be suppressed. The default value is `false`.
{rename, [{{atom(), atom(), integer()}, {atom(), atom()}}]}
  The value is a list of pairs, associating tuples `{Module, Name, Arity}` with tuples `{NewModule, NewName}`, specifying renamings of calls to remote functions. By default, the value is the empty list.

  The renaming affects only remote calls (also when disguised by import declarations); local calls within a module are not affected, and no function definitions are renamed. Since the arity cannot change, the new name is represented by `{NewModule, NewName}` only. Only calls matching the specified arity will match; multiple entries are necessary for renaming calls to functions that have the same module and function name, but different arities.

  This option can also be used to override the default renaming of calls which use obsolete function names.

{verbose, bool()}
  If the value is `true`, progress messages will be output while the program is running, unless the `quiet` option is `true`. The default value is `false`.