define_options.cc File Reference

Example program showing how to define and use GOptions : . More...

#include "goptions.h"
#include <iostream>

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Functions
GOptions	defineOptions ()
	Builds and returns a set of example options (definitions only).
int	main (int argc, char *argv[])
	Example entry point: parse inputs and read back resolved values.

Detailed Description

This example demonstrates an end-to-end pattern commonly used in GEMC-style modules:

1. Build a definition-only GOptions : instance (no parsing yet).
2. Construct a parsing GOptions : instance in main() using: GOptions(argc, argv, user_defined_options) .
3. Retrieve resolved values with typed getters such as getScalarInt() .

It also shows:

• Defining a boolean switch with defineSwitch() .
• Defining scalar options with defineOption() .
• Defining a structured option schema (sequence of maps) and providing a usable command-line example.

Definition in file define_options.cc.

Function Documentation

defineOptions()

GOptions defineOptions

(

)

This function intentionally does not parse any inputs. Instead, it returns a GOptions : populated with registrations:

• switches (presence-based booleans),
• scalar options,
• structured option schemas.

The returned object is then passed into the parsing constructor:

auto gopts = std::make_shared<GOptions>(argc, argv, defineOptions());

This pattern allows multiple components (modules/plugins) to contribute their own option definitions and then combine them before parsing.

What this example defines:

• Switch log: dummy switch that can be toggled by -log.
• Scalar runno: an integer option set via -runno=<value>.
• Scalar nthreads: an integer option controlling thread usage, with 0 meaning "use all cores".
• Structured gparticle: a schema representing generator particles as a sequence of maps, including mandatory keys flagged using goptions::NODFLT.

Returns

A GOptions : object populated with example switches and options.

Definition at line 55 of file define_options.cc.

main()

int main	(	int	argc,
		char *	argv[] )

This main() illustrates the common consumption flow:

1. Construct a parsing GOptions : instance using argc/argv and the definitions provided by defineOptions().
2. Query values from the resolved configuration.

Example invocations:

• Scalar option from command line:

  define_options -nthreads=8

• Dot-notation (if supported by the target option; shown here for illustration):

  define_options -verbosity.general=1

• Structured option payload (quoted so the shell does not split YAML-like characters):

  define_options -gparticle="[{name: e-, p: 2300, theta: 23.0}]"

Parameters

argc	Number of command-line arguments.
argv	Array of command-line argument strings.

Returns

Process exit code (EXIT_SUCCESS on success).

Definition at line 116 of file define_options.cc.