parseopts

Basic command-line options parser written in D. Unlike std.getopt, instead of passing information about flags as arguments to getopt, information is stored within a struct or class. This type is inspected by the function parseOpts, and parsing code is generated as necessary.

Example usage:

import parseopts;

struct MyConfig
{
    @shortFlag('v') int verbosity;
    @shortFlag('l') @longFlag("should-log") bool log;
    string filename;
    @ignore string importantSecrets;
}

void main(string[] args)
{
    MyConfig cfg = args.parseOpts!MyConfig;
    //...
}
//Used like: ./myprogram -v 7 --should-log --filename "prog.log"

By default, the flag for any given symbol is --symbol. So, to set the member filename, one would give the command line argument --filename "/dev/null". The default long flag can be overridden with the longFlag attribute. Using this sets the long flag of the member to any given non-empty alphanumeric string. By default, no short flags are generated. They may be set by annotating the member with the shortFlag attribute. These may be used like -v 7. For boolean types, simply -l. If the struct contains a member that should not be settable via command line arguments, the attribute ignore may be annotated.

There are various runtime options which can be passed to the function parseOpts which affects its behaviour.

• Bundling: Short flags can be packed together into a single argument, e.g. -abc is equivalent to -a -b -c.
• Passthrough: Unknown flags are ignored.
• Stop-on-non-option: If a value is parsed and it does not look like a flag, then an exception is raised.
• Consume: Arguments are replaced with null as they are parsed.

Help text may also be programmatically generated based on annotations. The type may be annotated with help to specify the general help text for the program, and member may be annotated with help to specify meaning of each flag.

Example usage:

@help("A simple webserver which echos all requests back to the user")
struct ServerConfig
{
    @help("The path where logfiles will be stored")
    string path;
    
    @help("Specify how much information the server should log")
    int verbosity;
    
    //...
}

Todo:

• Implement the required attribute
• Implement help text generation
• Add invariants to members to control the values they can take
• Ensure that parsing adheres to the POSIX syntax