It is possible to bind arguments to a variable storing their value, as an
alternative to explicitly calling ``program.get<T>(arg_name)`` or ``program[arg_name]``
This is currently implementeted for variables of type ``bool`` (this also
implicitly calls ``flag()``), ``int``, ``double``, ``std::string`` and
``std::vector<std::string>``. If the argument is not specified in the command
line, the default value (if set) is set into the variable.
```cpp
bool flagvar = false;
program.add_argument("--flagvar").store_into(flagvar);
int intvar = 0;
program.add_argument("--intvar").store_into(intvar);
double doublevar = 0;
program.add_argument("--doublevar").store_into(doublevar);
std::string strvar;
program.add_argument("--strvar").store_into(strvar);
std::vector<std::string> strvar_repeated;
program.add_argument("--strvar-repeated").append().store_into(strvar_repeated);
std::vector<std::string> strvar_multi_valued;
program.add_argument("--strvar-multi-valued").nargs(2).store_into(strvar_multi_valued);
```
It is sometimes desirable to offer an alias for an argument, but without it
appearing it in the usage. For example, to phase out a deprecated wording of
an argument while not breaking backwards compatible. This can be done with
the ``ArgumentParser::add_hidden_alias_for()` method.
```cpp
argparse::ArgumentParser program("test");
auto &arg = program.add_argument("--suppress").flag();
program.add_hidden_alias_for(arg, "--supress"); // old misspelled alias
```
Only those places in the README where an error is explicitly found in the
main function have been updated. Other uses of exit are left untouched as
there is not enough context to know if return will work in that location.
Signed-off-by: Sean Robinson <sean.robinson@scottsdalecc.edu>
Allows users to opt-out of std::exit call in default arguments without
needing to replace with new --help and --version arguments.
Signed-off-by: Sean Robinson <sean.robinson@scottsdalecc.edu>
This replaces the verbiage copied from the Python argparse documentation
and makes the code sample more concrete. This illustrates how to avoid the
multiple help output problem reported in #165.
Closes#165
Signed-off-by: Sean Robinson <sean.robinson@scottsdalecc.edu>
This allows updating attached object properties without holding external
references to the various Argument and ArgumentParser objects.
Closes#227
Signed-off-by: Sean Robinson <sean.robinson@scottsdalecc.edu>
This allows checking whether user input was processed into the parser
or any attached subparsers.
Closes#212
Signed-off-by: Sean Robinson <sean.robinson@scottsdalecc.edu>
FetchContent_MakeAvailable was added in CMake v3.14. Also includes
end-of-line whitespace clean-ups.
Signed-off-by: Sean Robinson <sean.robinson@scottsdalecc.edu>
