struct: changing meaning of obj.[fun ...] syntax.

Until now, the obj.[fun ...] syntax has uselessly denoted
exactly the same thing as [obj.fun ...]. This latter syntax
is what should be used for that meaning.

The new meaning of obj.[fun ...] will be that it performs
method dispatch, where obj is passed to obj.fun as
the leftmost argument: obj.[fun ...] is [obj.fun obj ...],
with obj evaluated once.

* share/txr/stdlib/struct.tl (qref): Expansion change done
here, with backward compat switch.

* share/txr/stdlib/termios.tl (termios (go-raw, go-cbreak)):
Some a.[b c] turned to [a.b c] here.

* tests/012/oop.tl (animal print): Likewise.

* tests/012/struct.tl: Likewise, and some expansion tests
updated to reflect the new expansion.

* txr.1: Documentation revised in multiple places and compat
note added.

5 files changed, 55 insertions, 25 deletions

diff --git a/share/txr/stdlib/struct.tl b/share/txr/stdlib/struct.tl
index 64cd2e76..2eecfbc7 100644
--- a/share/txr/stdlib/struct.tl
+++ b/share/txr/stdlib/struct.tl
@@ -223,11 +223,21 @@
              :))
          (((dw sym . args))
           (if (eq dw 'dwim)
-            ^[(slot ,obj ',(sys:check-slot form sym)) ,*args]
+            (let ((osym (gensym)))
+              (sys:check-slot form sym)
+              ^(slet ((,osym ,obj))
+                 ,(if (and (plusp sys:compat) (<= sys:compat 251))
+                    ^[(slot ,osym ',sym) ,*args]
+                    ^[(slot ,osym ',sym) ,osym ,*args])))
             :))
          (((dw sym . args) . more)
           (if (eq dw 'dwim)
-            ^(qref [(slot ,obj ',(sys:check-slot form sym)) ,*args] ,*more)
+            (let ((osym (gensym)))
+              (sys:check-slot form sym)
+              ^(qref (slet ((,osym ,obj))
+                       ,(if (and (plusp sys:compat) (<= sys:compat 251))
+                          ^[(slot ,osym ',sym) ,*args]
+                          ^[(slot ,osym ',sym) ,osym ,*args])) ,*more))
             :))
          (((sym . args))
           (let ((osym (gensym)))
diff --git a/share/txr/stdlib/termios.tl b/share/txr/stdlib/termios.tl
index 93fcc958..5d2423dc 100644
--- a/share/txr/stdlib/termios.tl
+++ b/share/txr/stdlib/termios.tl
@@ -56,15 +56,15 @@
   (if (boundp 'iexten)
     tio.(clear-lflags iexten))
   tio.(set-cflags cs8)
-  (set tio.[cc vmin] 1)
-  (set tio.[cc vtime] 0))
+  (set [tio.cc vmin] 1)
+  (set [tio.cc vtime] 0))
 
 (defmeth termios go-cbreak (tio)
   tio.(clear-iflags icrnl)
   tio.(clear-lflags icanon)
   tio.(set-lflags isig)
-  (set tio.[cc vmin] 1)
-  (set tio.[cc vtime] 0))
+  (set [tio.cc vmin] 1)
+  (set [tio.cc vtime] 0))
 
 (defmeth termios string-encode (tio)
   (let ((*print-base* 16))
diff --git a/tests/012/oop.tl b/tests/012/oop.tl
index 51dadbf3..ac93790f 100644
--- a/tests/012/oop.tl
+++ b/tests/012/oop.tl
@@ -2,7 +2,7 @@
 
 (defstruct animal nil
   (:function whoami () "n/a")
-  (:method print (self stream : pretty-p) (put-string self.[whoami] stream)))
+  (:method print (self stream : pretty-p) (put-string [self.whoami] stream)))
 
 (defstruct dog animal
   (:function whoami () "dog"))
diff --git a/tests/012/struct.tl b/tests/012/struct.tl
index 9de3f832..88f37e4d 100644
--- a/tests/012/struct.tl
+++ b/tests/012/struct.tl
@@ -31,9 +31,9 @@
 (test (expand 's.a)
       (slot s 'a))
 (test (expand 's.[a])
-      [(slot s 'a)])
+      [(slot s 'a) s])
 (test (expand 's.[a b c])
-      [(slot s 'a) b c])
+      [(slot s 'a) s b c])
 
 (set *gensym-counter* 0)
 (stest (ignwarn (expand 's.(a)))
@@ -44,9 +44,9 @@
        "(call (slot s 'a)\n                     \
        \      s b c)")
 (test (expand 's.[a].d)
-      (slot [(slot s 'a)] 'd))
+      (slot [(slot s 'a) s] 'd))
 (test (expand 's.[a b c].d)
-      (slot [(slot s 'a) b c] 'd))
+      (slot [(slot s 'a) s b c] 'd))
 (set *gensym-counter* 0)
 (stest (ignwarn (expand 's.(a).d))
        "(slot (call (slot s 'a)\n               \
@@ -104,7 +104,7 @@
 (stest bz
        "#S(baz array #(1 2 3) increment #<interpreted fun: lambda (self which delta)>)")
 
-(test bz.[array 2] 3)
+(test [bz.array 2] 3)
 (test bz.(increment 0 42) 43)
 (test bz.array #(43 2 3))
 (test [(meth bz increment) 1 5] 7)
diff --git a/txr.1 b/txr.1
index 84cde4e5..4b14fca9 100644
--- a/txr.1
+++ b/txr.1
@@ -26727,9 +26727,9 @@ is visible. Consequently,
 may be used to terminate the execution of the function
 and return a value.
 Such functions are called using the
-.code "instance.[name arg ...]"
-syntax which doesn't insert the instance into
-the argument list.
+.code "(call instance.name arg ...)"
+or else the DWIM brackets syntax
+.codn "[instance.name arg ...]" .
 
 The remarks about inheritance and overriding
 in the description of
@@ -27422,13 +27422,18 @@ is evaluated only once:
   (qref o (n arg ...)) <--> (call (slot o 'n) o arg ...)
 .brev
 
-A DWIM designator indicates that the named slot is a function or an
-indexable or callable object. The following equivalence applies:
+A DWIM designator similarly indicates that the named slot is a function,
+and arguments are to be applied to it. The following equivalence applies:
 
 .verb
-  (qref obj [name arg ...])  <-->  [(slot obj 'name) arg ...]
+  (qref obj [name arg ...])  <-->  [(slot obj 'name) o arg ...]
 .brev
 
+Therefore, under this equivalence, this syntax provides the usual Lisp-1-style
+evaluation rule via the
+.code dwim
+operator.
+
 If the
 .meta object-form
 has the syntax
@@ -27468,7 +27473,7 @@ is the slot not accessed, but the argument expressions are not evaluated.
   (defvarl s (new foo))
 
   ;; access third element of s.array:
-  s.[array 2]  -->  3
+  [s.array 2]  -->  3
 
   ;; increment first element of array by 42
   s.(increment 0 42)  -->  43
@@ -29120,11 +29125,12 @@ which may be used to invoke them, such as:
 .mets << object .(function-name < arg << ... )
 .brev
 
-However, those introduced as "Function" do not operate on an instance. For
-brevity, their syntax is nevertheless exemplified as
+However, those introduced as "Function" do not operate on an instance.
+Their syntax is likewise indicated using the notation that may be used
+to invoke them:
 
 .verb
-.mets << object .'['function-name < arg << ... ']'
+.mets <> '[' object .function-name < arg << ... ']'
 .brev
 
 If such a invocation is actually used, the
@@ -29133,7 +29139,7 @@ instance only serves for identifying the struct type whose static slot
 .code function-name
 provides the function;
 .meta object
-doesn't participate in the call. An object is not required since
+doesn't participate in the call. An object is not strictly required since
 the function can be called using
 
 .verb
@@ -29543,7 +29549,7 @@ is invoked.
 
 .coNP Function @ from-list
 .synb
-.mets << object .'['from-list << list ']'
+.mets <> '[' object .from-list << list ']'
 .syne
 .desc
 If a
@@ -29574,7 +29580,7 @@ will always return a plain list of items.
 
 .coNP Function @ derived
 .synb
-.mets << object .'['derived < supertype << subtype ']'
+.mets <> '[' object .derived < supertype << subtype ']'
 .syne
 .desc
 If a structure type supports a function called
@@ -77530,6 +77536,20 @@ 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 251
+Until \*(TX 251, the syntax
+.code "obj.[fun arg]"
+was equivalent to
+.codn "[obj.fun arg]" ,
+providing little utility.
+A compatibility value of 251 or lower restores that behavior. The new
+behavior is that
+.code "obj.[fun arg]"
+is equivalent to
+.codn "obj.[fun obj arg]" ,
+with
+.code obj
+evaluated only once, performing method dispatch.
 .IP 248
 Until \*(TX 248, the
 .code hash-revget