Fix poorly chosen :postinit order.

* struct.c (call_postinitfun_chain): call base
handlers before derived ones, except in backward
compatibility mode.

* txr.1: Updated documentation of :postinit,
and added compatibility note.

2 files changed, 29 insertions, 14 deletions

diff --git a/struct.c b/struct.c
index 77e57c2e..7e022ed9 100644
--- a/struct.c
+++ b/struct.c
@@ -366,10 +366,14 @@ static void call_initfun_chain(struct struct_type *st, val strct)
 static void call_postinitfun_chain(struct struct_type *st, val strct)
 {
   if (st) {
-    if (st->postinitfun)
+    int derived_first = (opt_compat && opt_compat <= 148);
+
+    if (derived_first && st->postinitfun)
       funcall1(st->postinitfun, strct);
     if (st->super)
       call_postinitfun_chain(st->super_handle, strct);
+    if (!derived_first && st->postinitfun)
+      funcall1(st->postinitfun, strct);
   }
 }
 
diff --git a/txr.1 b/txr.1
index 10e6fde4..eeb8cf56 100644
--- a/txr.1
+++ b/txr.1
@@ -19897,29 +19897,30 @@ The
 .code :postinit
 specifier is very similar to
 .codn :init .
-There are two differences. The first difference
-is that
+Both specify forms which are evaluated during object instantiation.
+The difference is that the
 .codn body-form -s
+of a
+.code :postinit
 are evaluated after other initializations have taken
-place. The argument material from the
+place, including the
+.code :init
+initializations, as a second pass. By the time
+.code :postinit
+initialization runs, the argument material from the
 .codn make-struct ,
 .code new
 or
 .code lnew
 invocation has already been processed and stored
 into slots.
-The second difference is that
-.code :postinit
-actions registered at different levels of the type's
-inheritance hierarchy are invoked in the opposite
-order compared to
+Like
 .code :init
-action. The
+actions,
 .code :postinit
-specific to a derived struct type is called before
-the
-.code :postinit
-of its base type.
+actions registered at different levels of the type's
+inheritance hierarchy are invoked in the base-to-derived
+order.
 .meIP (:fini <> ( param ) << body-form *)
 The
 .code :fini
@@ -43747,6 +43748,16 @@ of these version values, the described behaviors are provided if
 is given an argument which is equal or lower. For instance
 .code "-C 103"
 selects the behaviors described below for version 105, but not those for 102.
+.IP 148
+Up until version 148, the
+.code :postinit
+handlers specified in a
+.code defstruct
+were executed in derived-to-base order, opposite to the
+order of execution of
+.code :init
+handlers. Specifying 148 or earlier compatibility provides this
+old behavior.
 .IP 145
 In versions 144 and 145, \*(TX opened files in text mode on Cygwin,
 enabling conversion between CR-LF line endings and abstract newline