Clone & Merge Example

Independent copies and default value merging.

Source Code

const std = @import("std");
const Io = std.Io;
const envMod = @import("env");

pub fn main(init: std.process.Init) !void {
    const io = init.io;
    const allocator = init.gpa;

    var env = envMod.Env.init(allocator, .{});
    defer env.deinit();

    try env.set("APP_NAME", "MyApp");
    try env.set("PORT", "8080");
    try env.set("DEBUG", "true");

    var stdoutBuffer: [0x100]u8 = undefined;
    var stdoutWriter = Io.File.stdout().writer(io, &stdoutBuffer);
    const stdout = &stdoutWriter.interface;

    try stdout.print("=== Clone & Merge Example ===\n\n", .{});

    try stdout.print("Original env:\n", .{});
    for (env.keys()) |key| {
        try stdout.print("  {s} = {s}\n", .{ key, env.get(key).? });
    }

    var cloned = try env.clone();
    defer cloned.deinit();

    try stdout.print("\nCloned env (independent copy):\n", .{});
    for (cloned.keys()) |key| {
        try stdout.print("  {s} = {s}\n", .{ key, cloned.get(key).? });
    }

    try cloned.set("PORT", "9090");
    try cloned.set("NEW_KEY", "new_value");

    try stdout.print("\nAfter modifying clone:\n", .{});
    try stdout.print("  Original PORT = {s}\n", .{env.get("PORT").?});
    try stdout.print("  Cloned PORT = {s}\n", .{cloned.get("PORT").?});
    try stdout.print("  Original has NEW_KEY = {}\n", .{env.contains("NEW_KEY")});
    try stdout.print("  Cloned has NEW_KEY = {}\n", .{cloned.contains("NEW_KEY")});

    var defaults = envMod.Env.init(allocator, .{});
    defer defaults.deinit();

    try defaults.set("PORT", "3000");
    try defaults.set("LOG_LEVEL", "info");
    try defaults.set("TIMEOUT", "30");

    try stdout.print("\nDefaults env:\n", .{});
    for (defaults.keys()) |key| {
        try stdout.print("  {s} = {s}\n", .{ key, defaults.get(key).? });
    }

    try env.merge(&defaults);

    try stdout.print("\nAfter merging defaults into env:\n", .{});
    for (env.keys()) |key| {
        try stdout.print("  {s} = {s}\n", .{ key, env.get(key).? });
    }
    try stdout.flush();
}

Running

zig-out/bin/clone_merge_example

Example Output

=== Clone & Merge Example ===

Original env:
  APP_NAME = MyApp
  PORT = 8080
  DEBUG = true

Cloned env (independent copy):
  APP_NAME = MyApp
  PORT = 8080
  DEBUG = true

After modifying clone:
  Original PORT = 8080
  Cloned PORT = 9090
  Original has NEW_KEY = false
  Cloned has NEW_KEY = true

Defaults env:
  PORT = 3000
  LOG_LEVEL = info
  TIMEOUT = 30

After merging defaults into env:
  APP_NAME = MyApp
  PORT = 3000
  DEBUG = true
  LOG_LEVEL = info
  TIMEOUT = 30

Before / After

Before merging defaults:

APP_NAME=MyApp
PORT=8080
DEBUG=true

Defaults store:

PORT=3000
LOG_LEVEL=info
TIMEOUT=30

After merge(&defaults) (other wins):

APP_NAME=MyApp
PORT=3000
DEBUG=true
LOG_LEVEL=info
TIMEOUT=30

See Also

• Clone & Merge Guide for usage details
• API Reference for the full API