Modular, context-aware and aspect-oriented dendritic Nix configurations.
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Update custom-classes.mdx
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# included at users who can fix things with nix.
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den.aspects.tux.includes = [ nix-allowed ];
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```
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#### Example: An impermanence class
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The following example, creates a forwarding class that is propagated only
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when `environment.persistance` option is available in the host (the impermanence module was imported in host)
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One cool thing about these custom classes is that aspects can simply define
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settings at the new class, without having to worry if the options they depend or
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some capability is enabled.
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The froward-guard itself is reponsible checking in only one place, instead of having `mkIf` in a lot of places.
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```nix
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# Custom `persys` forwards config into nixos.environment.persistance."/nix/persist/system"
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# only if environment.persistance option is present.
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persys = { class, aspect-chain }: den._.forward {
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each = lib.singleton true;
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fromClass = _: "persys";
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intoClass = _: class;
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intoPath = _: [ "environment" "persistance" "/nix/persist/system" ];
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fromAspect = _: lib.head aspect-chain;
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guard = { options, ... }@osArgs: options ? environment.persistance;
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};
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den.hosts.my-laptop.includes = [ persys ];
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# becomes nixos.environment.persistance."/nix/persist/system".hideMounts = true;
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den.aspects.my-laptop.persys.hideMounts = true;
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```