lib: add usage docs

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David Arnold 2021-03-01 14:37:43 -05:00
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- [Cachix](./cachix/README.md)
- [Extern](./extern/README.md)
- [Hosts](./hosts/README.md)
- [Lib](./lib/README.md)
- [Modules](./modules/README.md)
- [Overlays](./overlays/README.md)
- [Overrides](./overrides/README.md)

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lib/README.md Normal file
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# Lib
The lib directory mirrors the upstream concepts of [`nixpkgs:./lib`][nixpkgs-lib],
[`nixpkgs:./nixos/lib`][nixpkgs-nixos-lib] and [`nixpkgs:./pkgs/pkgs-lib`][nixpkgs-pkgs-lib],
but also occasionally [`nixpkgs:./pkgs/build-support`][nixpkgs-pkgs-build-support].
It comes with functions necesary to declutter `devos` itself, but you are
welcome to extend it to your needs.
For example:
- you want to add a library function that depends on some packages
and use it throughout your devos environment: place it into `./lib`
as if you would place it into [`nixpkgs:./pkgs/pkgs-lib`][nixpkgs-pkgs-lib].
- you want to add library functions that don't depend on `pkgs`: place
them into `./lib` as if you would place them into [`nixpkgs:./lib`][nixpkgs-lib].
- need to try out a newish custom build support: place it here before
upstreaming into [`nixpkgs:./pkgs/build-support`][nixpkgs-pkgs-build-support].
- you want to reutilize certain module configuration functions or helpers:
place them into `./lib` as if you would place them into [`nixpkgs:./nixos/lib`][nixpkgs-nixos-lib].
Once your library grows, we recoomend you start organizing them into subfolders
analogous `nixpkgs`:
| `nixpkgs` | `devos` |
| ---------------------- | ------------------ |
| `./lib` | `./lib` |
| `./pkgs/pkgs-lib` | `./lib/pkgs-lib` |
| `./nixos/lib` | `./lib/nixos-lib` |
| `./pkgs/build-support` | `./lib/pkgs-build` |
## Example
lib/nixos-lib/mkCustomI3BindSym/default.nix:
```nix
{ pkgs, writers, ... }:
{ name, cmd, workspace, baseKey }:
let
isWorkspaceEmpty = writers.writePython3 "is-workspace-empty" {
libraries = [ pkgs.python3Packages.i3ipc ];
} (builtins.readFile ./is-workspace-empty.py);
ws = builtins.toString workspace;
in
''
# ${name}
#bindsym ${baseKey}+${ws} workspace ${ws}; exec ${cmd}
bindsym ${baseKey}+${ws} workspace ${ws}; exec bash -c "${isWorkspaceEmpty} && ${cmd}"
''
```
lib/nixos-lib/mkCustomI3BindSym/is-workspace-empty.py:
```python
# returns 0/1 if current workspace is empty/non-empty
import i3ipc
i3 = i3ipc.Connection()
tree = i3.get_tree()
def current_workspace():
return tree.find_focused().workspace()
if current_workspace().leaves():
print("Error current workspace is not empty")
exit(1)
exit(0)
```
lib/default.nix:
```nix
{ nixos, pkgs, ... }:
# ...
{
# ...
mkCustomI3BindSym = pkgs.callPackage ./nixos-lib/mkCustomI3BindSym { };
}
```
[nixpkgs-lib]: https://github.com/NixOS/nixpkgs/tree/master/lib
[nixpkgs-pkgs-lib]: https://github.com/NixOS/nixpkgs/tree/master/pkgs/pkgs-lib
[nixpkgs-pkgs-build-support]: https://github.com/NixOS/nixpkgs/tree/master/pkgs/build-support
[nixpkgs-nixos-lib]: https://github.com/NixOS/nixpkgs/tree/master/nixos/lib