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Diffstat (limited to 'Documentation/technical/api-parse-options.txt')
| -rw-r--r-- | Documentation/technical/api-parse-options.txt | 146 |
1 files changed, 110 insertions, 36 deletions
diff --git a/Documentation/technical/api-parse-options.txt b/Documentation/technical/api-parse-options.txt index 539863b1f9..1f2db31312 100644 --- a/Documentation/technical/api-parse-options.txt +++ b/Documentation/technical/api-parse-options.txt @@ -1,7 +1,7 @@ parse-options API ================= -The parse-options API is used to parse and massage options in git +The parse-options API is used to parse and massage options in Git and to provide a usage help with consistent look. Basics @@ -21,7 +21,7 @@ that allow to change the behavior of a command. * There are basically two forms of options: 'Short options' consist of one dash (`-`) and one alphanumeric character. - 'Long options' begin with two dashes (`\--`) and some + 'Long options' begin with two dashes (`--`) and some alphanumeric characters. * Options are case-sensitive. @@ -29,9 +29,9 @@ that allow to change the behavior of a command. The parse-options API allows: -* 'sticked' and 'separate form' of options with arguments. - `-oArg` is sticked, `-o Arg` is separate form. - `\--option=Arg` is sticked, `\--option Arg` is separate form. +* 'stuck' and 'separate form' of options with arguments. + `-oArg` is stuck, `-o Arg` is separate form. + `--option=Arg` is stuck, `--option Arg` is separate form. * Long options may be 'abbreviated', as long as the abbreviation is unambiguous. @@ -39,11 +39,14 @@ The parse-options API allows: * Short options may be bundled, e.g. `-a -b` can be specified as `-ab`. * Boolean long options can be 'negated' (or 'unset') by prepending - `no-`, e.g. `\--no-abbrev` instead of `\--abbrev`. + `no-`, e.g. `--no-abbrev` instead of `--abbrev`. Conversely, + options that begin with `no-` can be 'negated' by removing it. + Other long options can be unset (e.g., set string to NULL, set + integer to 0) by prepending `no-`. -* Options and non-option arguments can clearly be separated using the `\--` - option, e.g. `-a -b \--option \-- \--this-is-a-file` indicates that - `\--this-is-a-file` must not be processed as an option. +* Options and non-option arguments can clearly be separated using the `--` + option, e.g. `-a -b --option -- --this-is-a-file` indicates that + `--this-is-a-file` must not be processed as an option. Steps to parse options ---------------------- @@ -60,16 +63,22 @@ Steps to parse options . in `cmd_foo(int argc, const char **argv, const char *prefix)` call - argc = parse_options(argc, argv, builtin_foo_options, builtin_foo_usage, flags); + argc = parse_options(argc, argv, prefix, builtin_foo_options, builtin_foo_usage, flags); + `parse_options()` will filter out the processed options of `argv[]` and leave the non-option arguments in `argv[]`. `argc` is updated appropriately because of the assignment. + +You can also pass NULL instead of a usage array as the fifth parameter of +parse_options(), to avoid displaying a help screen with usage info and +option list. This should only be done if necessary, e.g. to implement +a limited parser for only a subset of the options that needs to be run +before the full parser, which in turn shows the full help message. ++ Flags are the bitwise-or of: `PARSE_OPT_KEEP_DASHDASH`:: - Keep the `\--` that usually separates options from + Keep the `--` that usually separates options from non-option arguments. `PARSE_OPT_STOP_AT_NON_OPTION`:: @@ -77,6 +86,28 @@ Flags are the bitwise-or of: Using this flag, processing is stopped at the first non-option argument. +`PARSE_OPT_KEEP_ARGV0`:: + Keep the first argument, which contains the program name. It's + removed from argv[] by default. + +`PARSE_OPT_KEEP_UNKNOWN`:: + Keep unknown arguments instead of erroring out. This doesn't + work for all combinations of arguments as users might expect + it to do. E.g. if the first argument in `--unknown --known` + takes a value (which we can't know), the second one is + mistakenly interpreted as a known option. Similarly, if + `PARSE_OPT_STOP_AT_NON_OPTION` is set, the second argument in + `--unknown value` will be mistakenly interpreted as a + non-option, not as a value belonging to the unknown option, + the parser early. That's why parse_options() errors out if + both options are set. + +`PARSE_OPT_NO_INTERNAL_HELP`:: + By default, parse_options() handles `-h`, `--help` and + `--help-all` internally, by showing a help screen. This option + turns it off and allows one to add custom handlers for these + options, or to just leave them unknown. + Data Structure -------------- @@ -85,37 +116,49 @@ say `static struct option builtin_add_options[]`. There are some macros to easily define options: `OPT__ABBREV(&int_var)`:: - Add `\--abbrev[=<n>]`. + Add `--abbrev[=<n>]`. + +`OPT__COLOR(&int_var, description)`:: + Add `--color[=<when>]` and `--no-color`. + +`OPT__DRY_RUN(&int_var, description)`:: + Add `-n, --dry-run`. -`OPT__DRY_RUN(&int_var)`:: - Add `-n, \--dry-run`. +`OPT__FORCE(&int_var, description)`:: + Add `-f, --force`. -`OPT__QUIET(&int_var)`:: - Add `-q, \--quiet`. +`OPT__QUIET(&int_var, description)`:: + Add `-q, --quiet`. -`OPT__VERBOSE(&int_var)`:: - Add `-v, \--verbose`. +`OPT__VERBOSE(&int_var, description)`:: + Add `-v, --verbose`. `OPT_GROUP(description)`:: Start an option group. `description` is a short string that describes the group or an empty string. Start the description with an upper-case letter. -`OPT_BOOLEAN(short, long, &int_var, description)`:: - Introduce a boolean option. - `int_var` is incremented on each use. +`OPT_BOOL(short, long, &int_var, description)`:: + Introduce a boolean option. `int_var` is set to one with + `--option` and set to zero with `--no-option`. + +`OPT_COUNTUP(short, long, &int_var, description)`:: + Introduce a count-up option. + `int_var` is incremented on each use of `--option`, and + reset to zero with `--no-option`. `OPT_BIT(short, long, &int_var, description, mask)`:: Introduce a boolean option. If used, `int_var` is bitwise-ored with `mask`. -`OPT_SET_INT(short, long, &int_var, description, integer)`:: +`OPT_NEGBIT(short, long, &int_var, description, mask)`:: Introduce a boolean option. - If used, set `int_var` to `integer`. + If used, `int_var` is bitwise-anded with the inverted `mask`. -`OPT_SET_PTR(short, long, &ptr_var, description, ptr)`:: - Introduce a boolean option. - If used, set `ptr_var` to `ptr`. +`OPT_SET_INT(short, long, &int_var, description, integer)`:: + Introduce an integer option. + `int_var` is set to `integer` with `--option`, and + reset to zero with `--no-option`. `OPT_STRING(short, long, &str_var, arg_str, description)`:: Introduce an option with string argument. @@ -129,25 +172,56 @@ There are some macros to easily define options: Introduce an option with date argument, see `approxidate()`. The timestamp is put into `int_var`. +`OPT_EXPIRY_DATE(short, long, &int_var, description)`:: + Introduce an option with expiry date argument, see `parse_expiry_date()`. + The timestamp is put into `int_var`. + `OPT_CALLBACK(short, long, &var, arg_str, description, func_ptr)`:: Introduce an option with argument. The argument will be fed into the function given by `func_ptr` and the result will be put into `var`. See 'Option Callbacks' below for a more elaborate description. +`OPT_FILENAME(short, long, &var, description)`:: + Introduce an option with a filename argument. + The filename will be prefixed by passing the filename along with + the prefix argument of `parse_options()` to `prefix_filename()`. + `OPT_ARGUMENT(long, description)`:: Introduce a long-option argument that will be kept in `argv[]`. +`OPT_NUMBER_CALLBACK(&var, description, func_ptr)`:: + Recognize numerical options like -123 and feed the integer as + if it was an argument to the function given by `func_ptr`. + The result will be put into `var`. There can be only one such + option definition. It cannot be negated and it takes no + 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. + +`OPT_NOOP_NOARG(short, long)`:: + Introduce an option that has no effect and takes no arguments. + Use it to hide deprecated options that are still to be recognized + and ignored silently. + 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. `'e'` for `-e`, use `0` to omit), * `long` is a string for the long option - (e.g. `"example"` for `\--example`, use `NULL` to omit), + (e.g. `"example"` for `--example`, use `NULL` to omit), * `int_var` is an integer variable, @@ -170,9 +244,9 @@ The function must be defined in this form: The callback mechanism is as follows: -* Inside `funct`, the only interesting member of the structure +* 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 + `*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 into an `unsigned long` variable. @@ -197,10 +271,10 @@ Examples -------- See `test-parse-options.c` and -`builtin-add.c`, -`builtin-clone.c`, -`builtin-commit.c`, -`builtin-fetch.c`, -`builtin-fsck.c`, -`builtin-rm.c` +`builtin/add.c`, +`builtin/clone.c`, +`builtin/commit.c`, +`builtin/fetch.c`, +`builtin/fsck.c`, +`builtin/rm.c` for real-world examples. |