Adding with-resources macro.

* share/txr/stdlib/with-resources.tl: New file.

* lisplib.c (with_resource_set_entries, with_resources_instantiate):
New static functions.
(lisplib_init): Register new functions under dlt_register.

* txr.1: Document with-resources.

1 files changed, 17 insertions, 0 deletions

diff --git a/share/txr/stdlib/with-resources.tl b/share/txr/stdlib/with-resources.tl
new file mode 100644
index 00000000..2a8c6791
--- /dev/null
+++ b/share/txr/stdlib/with-resources.tl
@@ -0,0 +1,17 @@
+(defmacro with-resources (res-bindings . body)
+  (tree-case res-bindings
+    (((var init cleanup) . rest)
+     ^(let ((,var ,init))
+        (when ,var
+          (unwind-protect
+            (with-resources ,rest ,*body)
+            ,cleanup))))
+    (((var init) . rest)
+     ^(let ((,var ,init))
+        (with-resources ,rest ,*body)))
+    ((var . rest)
+     ^(let (,var)
+        (with-resources ,rest ,*body)))
+    (nil
+      ^(progn ,*body))
+    (other (error "with-resources: bad syntax"))))