`OPT__ABBREV(&int_var)`::
Add `\--abbrev[=<n>]`.
+`OPT__COLOR(&int_var, description)`::
+ Add `\--color[=<when>]` and `--no-color`.
+
`OPT__DRY_RUN(&int_var)`::
Add `-n, \--dry-run`.
arguments. Short options that happen to be digits take
precedence over it.
+`OPT_COLOR_FLAG(short, long, &int_var, description)`::
+ Introduce an option that takes an optional argument that can
+ have one of three values: "always", "never", or "auto". If the
+ argument is not given, it defaults to "always". The `--no-` form
+ works like `--long=never`; it cannot take an argument. If
+ "always", set `int_var` to 1; if "never", set `int_var` to 0; if
+ "auto", set `int_var` to 1 if stdout is a tty or a pager,
+ 0 otherwise.
+
The last element of the array must be `OPT_END()`.
If not stated otherwise, interpret the arguments as follows:
* `short` is a character for the short option
- (e.g. `\'e\'` for `-e`, use `0` to omit),
+ (e.g. `{apostrophe}e{apostrophe}` for `-e`, use `0` to omit),
* `long` is a string for the long option
(e.g. `"example"` for `\--example`, use `NULL` to omit),
The callback mechanism is as follows:
* Inside `func`, the only interesting member of the structure
- given by `opt` is the void pointer `opt->value`.
- `\*opt->value` will be the value that is saved into `var`, if you
+ given by `opt` is the void pointer `opt\->value`.
+ `\*opt\->value` will be the value that is saved into `var`, if you
use `OPT_CALLBACK()`.
- For example, do `*(unsigned long *)opt->value = 42;` to get 42
+ For example, do `*(unsigned long *)opt\->value = 42;` to get 42
into an `unsigned long` variable.
* Return value `0` indicates success and non-zero return