private static TOptions InternalParse <TOptions>(string[] args, int offsetInArray, ArgumentGroupInfo arguments, ParserOptions parseOptions)
where TOptions : new()
{
TOptions options = new TOptions();
int currentLogicalPosition = 0;
// let's match them to actual required args, in positional
if (arguments.RequiredArguments.Count > 0)
{
ParseRequiredParameters(args, offsetInArray, arguments, options, ref currentLogicalPosition);
}
// we are going to keep track of any properties that have not been specified so that we can set their default value.
var unmatchedOptionalProperties = ParseOptionalParameters(args, offsetInArray, arguments, options, ref currentLogicalPosition);
// for all the remaining optional properties, set their default value.
foreach (var property in unmatchedOptionalProperties)
{
//get the default value..
var value = property.GetCustomAttribute <OptionalArgumentAttribute>();
object defaultValue = value.DefaultValue;
// If we want to read values from the environment, try to get the value
if (parseOptions.ReadFromEnvironment && !value.IsCollection && parseOptions.VariableNamePrefix != null)
{
var envVar = Environment.GetEnvironmentVariable($"{parseOptions.VariableNamePrefix}{value.Name}");
if (!string.IsNullOrEmpty(envVar))
{
defaultValue = PropertyHelpers.GetValueForProperty(envVar, property);
}
}
property.SetValue(options, Convert.ChangeType(defaultValue, property.PropertyType));
}
return(options);
}