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| author | Sean Whitton <spwhitton@spwhitton.name> | 2021-02-27 16:30:40 -0700 |
|---|---|---|
| committer | Sean Whitton <spwhitton@spwhitton.name> | 2021-02-27 16:30:40 -0700 |
| commit | 9b33466662cb1a8d1cd4c3fcb4803f7844eb7461 (patch) | |
| tree | 26cf39f9fb16ac0c86d80b8ec691b06703aa3441 | |
| parent | cb136f7ac479f9d398d731590caae03ed1f49c78 (diff) | |
| download | consfigurator-9b33466662cb1a8d1cd4c3fcb4803f7844eb7461.tar.gz | |
plan for handling nested propspecs
Signed-off-by: Sean Whitton <spwhitton@spwhitton.name>
| -rw-r--r-- | doc/properties.rst | 6 | ||||
| -rw-r--r-- | doc/propspecs.rst | 34 |
2 files changed, 40 insertions, 0 deletions
diff --git a/doc/properties.rst b/doc/properties.rst index 771ef77..7a1c299 100644 --- a/doc/properties.rst +++ b/doc/properties.rst @@ -1,6 +1,12 @@ Properties ========== +Names +----- + +The names of properties may not end in the character ``.``, because that has a +special meaning in unevaluated property application specifications. + Property subroutines -------------------- diff --git a/doc/propspecs.rst b/doc/propspecs.rst index 7143f37..a3f8900 100644 --- a/doc/propspecs.rst +++ b/doc/propspecs.rst @@ -6,3 +6,37 @@ Combinators Currently supported: ``(unapply (foo 1 2 3))``, ``((foo 1 2 3) on-change (bar 4 5 6) on-change (baz 7 8 9))`` and combinations thereof. + +Unevaluated property application specifications +----------------------------------------------- + +In an atomic property application within an unevaluated property application +specification, if the symbol naming the property ends with the character +``.``, then the following special evaluation rules apply: + +1. The property to be applied is the property named by the symbol in the same + package and with the same name as the first element of the atomic property + application, but with the trailing period removed from the name. + +2. The first argument is not evaluated if it is a list whose first element is + a keyword, or a if it is a list of lists where the first element of the + first list is a keyword. + +3. The last argument is treated as an unevaluated property application + specification and is converted into a property application specification + according to the usual evaluation rules. + +This is intended to make applications of properties like DEPLOYS, +DEPLOYS-THESE and CHROOT:DEBOOTSTRAPPED, which take property application +specifications as arguments, easier to read and write in the most common +cases. For example, you can write:: + + (deploys. (:ssh (:sudo :as "spwhitton@athena.example.com")) athena.example.com + ((additional-property val1) + (a-further-property val2))) + +instead of:: + + (deploys '(:ssh (:sudo :as "spwhitton@athena.example.com")) athena.example.com + `((additional-property ,val1) + (a-further-property ,val2))) |