DynamicEnv 1.0.2-ci0006

DynamicEnv

.NET Standard 2.0 library that exposes environment variable interactions through a Dynamic object.

Getting Started

Install DynamicEnv from NuGet. E.g. from Visual Studio's Package Manager Console:

Install-Package DynamicEnv

Usage

You can then use the Env class to access environment variables succinctly via a dynamic object. You can use either dynamic member syntax or indexes (similar to a string dictionary, although this class does not currently implement any dictionary interface).

First you need an instance of Env:

using DynamicEnv;

//...

dynamic env = new Env();

//Or explicitly specify the environment target (the default when none is
//specified, like the line above, is EnvironmentVariableTarget.Process)
env = new Env(EnvironmentVariableTarget.Process)

//Or you can use one of the pre-initialized static instances:
env = Env.Machine; //Targets machine-level environment variables (Windows systems only)
env = Env.User;    //Targets user-level environment variables (Windows systems only)
env = Env.Process; //Targets process-level environment variables (this is the default)

Read an environment variable; note, their names may be case sensitive on some platforms (Linux/Mac):

string path;
path = env.PATH;
path = env["PATH"];

If the environment variable doesn't exist, then it'll return a null:

string empty;
empty = env.ThisVarDoesntExist;
empty = env["ThisVarDoesntExist"];
Assert.True(empty == null);

You can also set environment variables like this:

env.DataRoot = @"C:\Data";
env["DataRoot"] = @"C:\Data";

Deleting/clearing an environment variable is typically done by setting as null:

env.DataRoot = null;
env["DataRoot"] = null;

Enumerate environment variable names:

IEnumerable<string> varNames = env.GetDynamicMemberNames();
foreach (string name in varNames) {
    string val = env[name];
    Console.WriteLine($"{name}: {val}");
}

Errors

An unsupported value type (currently anything other than String) throws an ArgumentException:

env.Test = 454;

An unsupported index type (currently anything other than String) throws an IndexOutOfRangeException:

env[12] = "this won't work!";

And finally here's a gotcha that causes a RuntimeBinderException because .NET can't determine whether the null result is a string or a char[] parameter to the Console.WriteLine(...) method:

Console.WriteLine(env.ThisVarDoesntExist);

You can work around this by casting to string:

Console.WriteLine($"{env.ThisVarDoesntExist}");
Console.WriteLine((string)env.ThisVarDoesntExist);