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Diffstat (limited to 'doc/properties.rst')
| -rw-r--r-- | doc/properties.rst | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/doc/properties.rst b/doc/properties.rst index 7a1c299..ddae56b 100644 --- a/doc/properties.rst +++ b/doc/properties.rst @@ -10,8 +10,19 @@ special meaning in unevaluated property application specifications. Property subroutines -------------------- -A property is composed of four subroutines, which all take the same -arguments. At least one of ``:hostattrs`` or ``:apply`` must be present. +A property is composed of up to five subroutines, which all have the same +lambda list (take the same arguments). At least one of ``:hostattrs``, +``:apply`` or ``:unapply`` must be present. + +``:preprocess`` subroutines +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Executed in the root Lisp to modify the arguments that will be passed to the +other subroutines; should return a fresh list of the new arguments. This +subroutine is called on each atomic property application within a property +application specification before the effects of property combinators have been +applied. That is, it is effectively executed on atomic property applications +in isolation from the property application specifications in which they occur. ``:hostattrs`` subroutines ~~~~~~~~~~~~~~~~~~~~~~~~~~ |