Crate app_path

app-path

Create portable applications that keep files together with the executable.

Quick Start

use app_path::app_path;

// Files relative to your executable - not current directory!
let config = app_path!("config.toml");     // → /path/to/exe_dir/config.toml
let database = app_path!("data/users.db"); // → /path/to/exe_dir/data/users.db

// Environment overrides for deployment
let logs = app_path!("logs/app.log", env = "LOG_PATH");
// → Uses LOG_PATH if set, otherwise /path/to/exe_dir/logs/app.log

// Works like standard paths - all Path methods available
if config.exists() {
    let content = std::fs::read_to_string(&config)?;
}

// Directory creation
logs.create_parents()?;            // Creates logs/ directory for the file
app_path!("cache").create_dir()?;  // Creates cache/ directory itself

Key Features

• Portable: Relative paths resolve to executable directory
• System integration: Absolute paths work as-is
• Zero dependencies: Only standard library
• High performance: Static caching, minimal allocations
• Thread-safe: Concurrent access safe
• Zero-cost: All Path methods available via Deref (e.g., exists(), is_file(), extension())

API Design

Constructors

• AppPath::new() - Application base directory: Returns the directory containing the executable
• AppPath::with() - Primary API: Create paths relative to application base directory
• AppPath::try_new() - Libraries: Fallible version for getting application base directory
• AppPath::try_with() - Libraries: Fallible version for creating relative paths
• AppPath::with_override() - Deployment: Environment-configurable paths
• AppPath::try_with_override() - Deployment (Fallible): Fallible environment-configurable paths
• AppPath::with_override_fn() - Advanced: Function-based override logic
• AppPath::try_with_override_fn() - Advanced (Fallible): Fallible function-based override logic

Directory Creation

• AppPath::create_parents() - Files: Creates parent directories for files
• AppPath::create_dir() - Directories: Creates directories (and parents)

Path Operations & Traits

• All Path methods: Available directly via Deref<Target=Path> (e.g., exists(), is_file(), file_name(), extension())
• AppPath::into_path_buf() - Conversion: Extract owned PathBuf from wrapper
• AppPath::into_inner() - Conversion: Alias for into_path_buf() following Rust patterns
• AppPath::to_bytes() - Ecosystem: Raw bytes for specialized libraries
• AppPath::into_bytes() - Ecosystem: Owned bytes for specialized libraries

Convenience Macros

• app_path! - Macro: Convenient syntax with optional environment overrides
• try_app_path! - Macro (Fallible): Returns Result for explicit error handling

Constructor Variants

This crate provides both panicking and fallible variants for most operations:

Panicking (Recommended)	Fallible (Libraries)	Use Case
AppPath::new()	AppPath::try_new()	Get application base directory
AppPath::with()	AppPath::try_with()	Create relative paths
AppPath::with_override()	AppPath::try_with_override()	Environment-configurable paths
AppPath::with_override_fn()	AppPath::try_with_override_fn()	Function-based override logic
app_path!	try_app_path!	Convenient macros

Macro Syntax Variants

Both app_path! and try_app_path! macros support four syntax forms for maximum flexibility:

// 1. Direct value
let config = app_path!("config.toml");
// → /path/to/exe_dir/config.toml

// 2. With environment override
let config = app_path!("config.toml", env = "CONFIG_PATH");
// → Uses CONFIG_PATH if set, otherwise /path/to/exe_dir/config.toml

// 3. With optional override value
let config = app_path!("config.toml", override = std::env::var("CONFIG_PATH").ok());
// → Uses CONFIG_PATH if available, otherwise /path/to/exe_dir/config.toml

// 4. With function-based override
let config = app_path!("config.toml", fn = || {
    std::env::var("CONFIG_PATH").ok()
});
// → Uses function result if Some, otherwise /path/to/exe_dir/config.toml

Variable Capturing in Macros

Both macros support variable capturing in complex expressions:

let version = "1.0";
let cache = app_path!(format!("cache-{version}"));

let user_ids = vec![123, 456];
let logs: Vec<_> = user_ids.iter()
    .map(|id| app_path!(format!("logs/user-{id}.log")))
    .collect();

Ecosystem Integration

AppPath works seamlessly with ecosystem crates through Deref<Target=Path>:

Serde Integration

use app_path::app_path;
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct Config {
    db_path: String,
}

let config = Config {
    db_path: app_path!("data/app.db").display().to_string(),
};

UTF-8 Path Serialization (camino)

use app_path::app_path;
use camino::Utf8PathBuf;

let static_dir = app_path!("web/static");
let utf8_static = Utf8PathBuf::from_path_buf(static_dir.into_path_buf())
    .map_err(|_| "Invalid UTF-8 path")?;

Cross-Platform Path Types (typed-path)

use app_path::app_path;
use typed_path::{WindowsPath, UnixPath};

let dist_dir = app_path!("dist");
let win_path = WindowsPath::new(&dist_dir.to_bytes());
let unix_path = UnixPath::new(&dist_dir.to_bytes());

Panic Conditions

AppPath::new() panics only if executable location cannot be determined:

• std::env::current_exe() fails (extremely rare system failure)
• Executable path is empty (indicates system corruption)

These represent unrecoverable system failures that occur at application startup. After the first successful call, the executable directory is cached and subsequent calls never panic.

For libraries or applications requiring graceful error handling, use the fallible variant AppPath::try_new() instead.

Macros

app_path

Convenience macro for creating AppPath instances with optional environment variable overrides.

try_app_path

Fallible version of app_path! that returns a Result instead of panicking.

Structs

AppPath

Creates paths relative to the executable location for portable applications.

Enums

AppPathError

Error type for AppPath operations.