From 53017aeaaf162f4668155001900cc24571595a43 Mon Sep 17 00:00:00 2001
From: Gianni Ceccarelli <gianni.ceccarelli@broadbean.com>
Date: Thu, 27 Jul 2023 15:00:18 +0100
Subject: untested start of attribute support

---
 bos-meta-class.sh | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

(limited to 'bos-meta-class.sh')

diff --git a/bos-meta-class.sh b/bos-meta-class.sh
index 1fedb45..4884d40 100644
--- a/bos-meta-class.sh
+++ b/bos-meta-class.sh
@@ -99,6 +99,55 @@ function bos/meta/class/find-method-into() {
     return 1
 }
 
+# get the attribute meta-object for the given attribute name, assuming
+# that the class that this metaclass describe, actuall has that
+# attribute
+function bos/meta/class/get-attribute-by-name-into() {
+    local -A bos_meta_class_attrs
+
+    # very manual method call, because I'm not sure I can make this
+    # work otherwise
+
+    local attribute_name='class-attributes'
+    local associated_class='bos/meta/class'
+
+    bos/meta/attribute/store-for-into bos_meta_class_attrs "$self"
+
+    return "${bos_meta_class_attrs[$1]}"
+}
+
+
+function bos/meta/class/find-attribute-into() {
+    local -n bos_meta_class_find_attribute_result="$1"
+    local class="$2"
+    local attribute_name="$4"
+
+    local mro_store; $self mro-for-into mro_store "$class"
+    local -n mro="$mro_store"
+
+    # minimal MRO: the class itself
+    if [[ "${#mro[@]}" -eq 0 ]]; then
+        mro=( "$class" )
+    fi
+
+    local bos_meta_class_for_class
+    local bos_class_from_mro
+
+    for bos_class_from_mro in "${mro[@]}"; do
+        bos-meta/metaclass-instance-for-class-into bos_meta_class_for_class "$bos_class_from_mro"
+
+        $bos_meta_class_for_class get-attribute-by-name-into bos_meta_class_find_attribute_result "$attribute_name"
+
+        if [[ -n "$bos_meta_class_find_attribute_result" ]]; then
+            return 0
+        fi
+    done
+
+    # TODO: better error / failure
+    >&2 echo "attribute $attribute_name not found via class $class"
+    return 1
+}
+
 # the method dispatcher
 function bos/meta/class/invoke() {
     local class="$1";shift
-- 
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