cargo-wop - cargo without project

How arguments are interpreted | Configuration | Development tasks | VS Code build commands | Related projects

Rust source files as self-contained projects. cargo-wop allows cargoto work with rust source file as if thy were full projects. This project is heavily inspired by cargo-script, cargo-eval. In contrast to these projects, cargo-wop is designed to be as close as possible to cargo and support all sensible subcommands.

Run a file as a script:

cargo wop my-script.rs

# equivalent call:
cargo wop run my-script.rs

Build artifacts defined in the script:

cargo wop build my-script.rs

Run tests defined in the script:

cargo wop test my-script.rs

How arguments are interpreted

For most commands cargo-wop rewrites the command line as follows:

# Original command-line
cargo wop [cargo-command] [script] [args...]

# Rewritten command line
cargo [cargo-command] --manifest-path [generated_manifest] [args...]

The manifest path points to a Cargo.toml file written to the project director in "~/.cargo/wop-cache/". The project directory will also contain the target folder.

At the moment the following cargo commands are supported: bench, build, check, clean, clippy, fmt, install, locate-project, metadata, pkgid, run, tree, test, verify-project.

Some commands use additional rules:

• new: create a new source file based on templates. Run cargo wop new to get a list of all available templates. Run cargo wop new TEMPLATE SOURCE.rs to create the file. For example use cargo wop new --lib SOURCE.rs to create a shared library
• run: all arguments are passed per default to the script, not to cargo. To pass arguments to cargo place them before a --. For example: cargo wop run my-script.rs --verbose -- ...
• build: is executed twice. Once to build the package and a second time to determine the generated build artifacts and copy them into the local folder
• build and run default to release builds. To disable this behavior, use the build-debug and run-debug commands
• install: no manifest path is added, but the --path argument to the manifest directory

Custom commands:

• manifest: print out the generated manifest
• write-manifest: write the manifest into the current working directory

If no command is specified, the default command is executed, run without additional configuration.

Configuration

Specifying dependencies | Building libraries | Default actions | File filters | Build scripts

Specifying dependencies

Dependencies are described in a cargo manifest embedded in the top-level comment. Importantly, the file must start with the comment for the manifest to be recognized. For example:

//! ```cargo
//! [dependencies]
//! serde = "1.0"
//! ```

Dependencies can also be local paths relative to the script file by using the standard cargo syntax:

//! ```cargo
//! [dependencies]
//! local_dep = { path = "./local_dep" }
//! ```

Building libraries

The embedded manifest can contain any keys recognized by cargo. cargo-wop normalizes this manifest and makes sure the source file is correctly included. It also normalizes any paths used to specify dependencies. To show the generated manifest use:

cargo wop manifest my-script.rs

For example, simply specify a [lib] target with the correct flags set to build a static C library:

//! My script
//!
//! ```cargo
//! [lib]
//! crate-type = ["cdylib"]
//!
//! [dependencies]
//! ```

This script can be built into a library via:

cargo wop build my-script.rs

Default actions

The default action can be configured by setting the "default-action" array in the embedded manifest file:

//! ```cargo
//! [cargo-wop]
//! default-action = [COMMAND, ..ARGS]
//! ```

It is interpreted as COMMAND FILE ..ARGS ..CLI_ARGS, where CLI_ARGS are the arguments passed via the command line. Without configuration, it corresponds to default-action = ["run"]. For example, to build the given file as a wasm32 library configure it as

//! ```cargo
//! [cargo-wop]
//! default-action = ["build", "--target", "wasm32-unknown--unknown"]
//! ```

File filters

For some applications it is helpful to rename the generated files. For example PyO3 extensions need to be stripped of their "lib" prefix on Linux systems. Cargo wop supports renaming files by specifying a filter dictionary

//! [cargo-wop]
//! filter = {  "libexample.so" = "example.so" }
//! ```

To not copy files into the current directory, map them to an empty string. For example, to not copy the debug information on Windows, use

//! [cargo-wop]
//! filter = {  "example.pdb" = "" }
//! ```

The files that are specified in the mapping do not need to be part of the build. Therefore, it is safe to include platform specific renames even in cross-platform files.

Build scripts

Build scripts can be configured by setting the package.build key to a script relative to the source file. For example:

//! [package]
//! build = "example_build.rs"

Note, that cargo executes the build script in the generated project directory in which the manifest is found, not the directory containing the script. One option, to use paths relative to the build script, is to change the directory at the start of the build script. Using the standard file!() macro:

fn main() {
    let self_path = std::path::PathBuf::from(file!());
    std::env::set_current_dir(self_path.parent().unwrap()).unwrap();

    // ...
}

VS Code build commands

To setup cargo wop as build command in VS Code, that can be accessed via "Ctrl-Shift-B", create the file .vscode/tasks.json with the following contents:

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "cargo wop",
            "type": "process",
            "command": "cargo",
            "args": ["wop", "${file}"],
            "group": "build",
            "options": {"cwd": "${fileDirname}"},
            "problemMatcher": ["$rustc"],
            "presentation": {"focus": true}
        },
        {
            "label": "cargo wop [task]",
            "type": "process",
            "command": "cargo",
            "args": ["wop", "${input:task}", "${file}"],
            "group": "build",
            "options": {"cwd": "${fileDirname}"},
            "problemMatcher": ["$rustc"],
            "presentation": {"focus": true}
        }
    ],
    "inputs": [
        {
          "type": "pickString",
          "id": "task",
          "description": "What task to run?",
          "options": [
            "build",
            "clippy",
            "clean",
            "fmt",
            "install",
            "test",
            "run"
          ],
          "default": "fmt"
        }
      ]
}

The task.json is documented here. Now pressing "Ctrl-Shift-B" and selecting cargo wop will execute the currently opened file using cargo wop.

Development tasks

Common tasks are bundled in the make.rs script. It can be used with cargo-wop itself. First install cargo-wop. Then run the make.rs script:

cargo install --path .
cargo wop make.rs precommit

Run cargo wop make.rs help to a see a list of available commands.

Related projects

• cargo-script and forks of it cargo-scripter, cargo-eval
• cargo-play
• cargo-temp