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File Processor Example

A practical example demonstrating the new lazy parsing API for zargs.

Building

zig build examples

Running

Show help:

zig build run-file-processor -- --help

Basic usage with defaults:

zig build run-file-processor

With verbose output:

zig build run-file-processor -- -v

Full example with all options:

zig build run-file-processor -- \
  --input=data.csv \
  --output=result.json \
  --format=xml \
  --max-size=2048 \
  --tags=important,urgent,reviewed \
  --verbose

Short flags:

zig build run-file-processor -- -i data.csv -o result.json -f json -m 512 -t alpha,beta -v

Features Demonstrated

Boolean flags: --verbose / -v
String arguments: --input / -i, --output / -o
Integer arguments: --max-size / -m
Enum arguments: --format / -f (json, xml, csv)
String lists: --tags / -t (comma-separated)
Help text: --help / -h
Default values: All arguments have sensible defaults

Code Structure

const Config = struct {
    // Define your configuration fields
    input: []const u8 = "input.txt",
    verbose: bool = false,
    format: Format = .json,
    
    // Define metadata for help text and short flags
    pub const meta = .{
        .input = .{ .short = 'i', .help = "Input file path" },
        .verbose = .{ .short = 'v', .help = "Enable verbose output" },
        .format = .{ .short = 'f', .help = "Output format" },
    };
};

// Parse in one line!
const config = try parse.parse(Config, allocator, argv);

Memory Model

This example uses the arena allocator pattern where all parsed strings live until program exit. This is appropriate for command-line applications where:

Arguments are parsed once at startup
Values are used throughout the program lifetime
No need for complex lifetime management

Notes

The "memory address leaked" messages in GPA output are expected and safe
The arena allocator manages all string lifetimes automatically
Unknown arguments are silently ignored (multi-module friendly)

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