fprettify && multi-line help message

README.md

@@ -5,7 +5,7 @@ Modern Fortran command line parser, implemented with OOP.
 ## Example
 ```fortran
 program test
- use iso_fortran_env, only : stdout=>output_unit
+ use iso_fortran_env, only: stdout => output_unit
  use argparse
  implicit none
  character(len=10), parameter :: program_name = "qcalc"
@@ -16,17 +16,17 @@ program test
  call args%add_sc_option("-v", "--version", "show version info", show_version_info)
  call args%add_option_logical("-o", "--openmp", "use openmp or not") ! logical option has no default
  call args%add_option_logical("-m", "--mpi", "use mpi or not")
- call args%add_option_integer("-t", "--thread", "thread number, valid if openmp is set", 1)
- call args%add_option_integer("-p", "--process", "process number, valid if mpi is set", 1)
+ call args%add_option_integer("-t", "--thread", "thread number,\nit is valid only if openmp is set", 1)
+ call args%add_option_integer("-p", "--process", "process number,\nit is valid only if mpi is set", 1)
  call args%add_option_string("", "--chemical", "chemical formula", "H2O") ! short name can be empty
  call args%add_named_argument_string("input", "initialize file")
  call args%add_named_argument_string("output", "output file")
  call args%parse()
 
- if(args%has_option("--openmp")) then
+ if (args%has_option("--openmp")) then
  print '(A,I2,A)', "openmp is used, and we use ", args%get_option_integer("-t"), " threads"
  end if
- if(args%has_option("--mpi")) then
+ if (args%has_option("--mpi")) then
  print '(A,I2,A)', "mpi is used, and we use ", args%get_option_integer("-p"), " processes"
  end if
  print '(A,A)', "the calculated chemical is ", trim(args%get_option_string("--chemical"))
@@ -36,7 +36,7 @@ program test
  ! you can also print the cached `args` into INI file
  ! print '(/,A)', "All of the options and arguments are shown below"
  ! call args%print_as_ini(stdout, .true.)
- contains
+contains
  subroutine show_version_info
  print "(A)", trim(program_name)//" version 0.1.0"
  end subroutine show_version_info
@@ -50,17 +50,19 @@ usage: qcalc [options] [=input] [=output]
 A quantum physics calculation program.
 
 Options:
- -?, --help show this help message
- -v, --version show version info
- -o, --openmp use openmp or not
- -m, --mpi use mpi or not
- -t, --thread (integer) thread number, valid if openmp is set
- -p, --process (integer) process number, valid if mpi is set
- --chemical (string) chemical formula
+ -?, --help show this help message
+ -v, --version show version info
+ -o, --openmp use openmp or not
+ -m, --mpi use mpi or not
+ -t, --thread (integer) thread number,
+ it is valid only if openmp is set
+ -p, --process (integer) process number,
+ it is valid only if mpi is set
+ --chemical (string) chemical formula
 
 Named arguments:
- input (string) initialize file
- output (string) output file
+ input  (string) initialize file
+ output  (string) output file
 > qclac -o -t 4 input=input.txt output=out.bin
 openmp is used, and we use 4 threads
 the calculated chemical is H2O
@@ -178,13 +180,19 @@ subroutine print_help
 end subroutine
 ```
 
+### multi-line help message
+Some times, help message may be very long. You can use `\n` to as newline split mark. Of course, Fortran does not have escape characters. I just use some character split technique to realize this feature.
+
 ### print argparser
 
 You can print the argparser into INI file format. If the second dummy argument is set to `.true.`, then print help message as comments.
 ```fortran
 call args%print_as_ini(stdout, .true.)
 ```
 
+### `print_uasge` && `set_program_name`
+If you give none command line argument, the program will call `print_usage` and exit. It is just the first line of `print_help`. `set_program_name` only affects program name in `print_usage`, if you does not set it, it will use `argv[0]`.
+
 ## Reference
 
 This package works like my c++ package [argparse](https://github.com/0382/util/tree/main/cpp/argparse). They are imspired by c++ package [cmdline](https://github.com/tanakh/cmdline) and python's standard library package [argparse](https://docs.python.org/3/library/argparse.html).