chezray Ray Mendonsa's info droppings

Sample: Customizing Spring.NET configuration variable resolution

While I was playing around with Spring.Objects.Factory.Config.VariablePlaceholderConfigurer I came across a scenario that led me to look into implementing my own IVariableSource . Essentially I was using CommandLineArgsVariableSource as the preferred source, trying EnvironmentVariableSource next, and then finally defaulting to a config file. In this case, I wanted the environment variable name to be more specific (qualified with an application identifier) than the command line arg names (keep them short). This is really a generic strategy rewrite the variable name and delegate to an existing implementation.

public class PrefixedEnvironmentVariableSource : IVariableSource
    {
        // EnvironmentVariableSource to be wrapped by this instance
        private EnvironmentVariableSource environmentVariableSource;

        /// Prefix to be prepended to config variable names when searching for values in environment.
        public string Prefix { get; set; }

        public PrefixedEnvironmentVariableSource()
        {
            environmentVariableSource = new EnvironmentVariableSource();
            Prefix = String.Empty;
        }

        #region IVariableSource Members

        public string ResolveVariable(string name)
        {
            return environmentVariableSource.ResolveVariable(Prefix + name);
        }

        #endregion
    }

Posted at 09:18PM Sep 25, 2009 by raydoo in Software  |  Comments[0]