---
sidebar_label: Dependencies
---

# Dependencies

## Formats

The `[dependencies]` section supports three formats:

### String (registry)

```toml
[dependencies]
fmt = "10.1.1"
spdlog = "1.12"
catch2 = "3.4.0"
```

The version string is used as-is for registry lookup.

### Table (git)

```toml
[dependencies]
fmt = { git = "https://github.com/fmtlib/fmt", tag = "10.1.1" }
```

Fields: `git`, `branch`, `tag`, `rev`.

### Table (path)

```toml
[dependencies]
mylib = { path = "../mylib" }
```

## Registry

DCR uses a package registry for dependency lookup by name.

```toml
# ~/.dcr/config.toml
[[registry]]
name = "default"
url = "https://index.dcr.pm"
```

Registry priority: order in `config.toml`. The `DCR_INDEX_PATH` variable overrides the path to `index.json`.

## Git dependencies

DCR clones git repositories via `git2`:

- `branch` — switch to a branch
- `tag` — switch to a tag
- `rev` — switch to a specific commit
- `features` — feature flags (parsed, but does not affect build)

Cache path: `~/.dcr/git/<hash>/`.

## Path dependencies

Local paths. DCR automatically discovers include and lib directories from the neighbor's `dcr.toml`.

```toml
[dependencies]
mylib = { path = "/abs/path/to/lib" }
mylib = { path = "../relative/path" }
```

## dcr.lock

Dependency lock file. Contains package names and sources.

Created during `dcr build` when registry dependencies are present. Not updated during `dcr add` — only on the next `dcr build`.

## Resolution process

1. Load all dependencies (registry → git → path)
2. For path deps: recursively read their `dcr.toml`
3. For registry deps: search `index.json`
4. For git deps: clone to cache
5. Collect `include_dirs`, `lib_dirs`, `libs` for the compiler
