Allow fmt and escj to be used to calculate attributes.

* who.tl (attr-warning-macrolet): Do not warn when
fmt and escj are used on attributes. Instead, give
them a useful definition so they do what the
programmer wants: return a string.

* test/simple.tl: Trim it
to just the tags that should warn now. Also
fix a bug that rendered this case invalid:
unquote occurred with no backquote, and this
produced an undefined variable warning on
sym, which was treated by the test case's handler
as a false positive that made it pass.
New test case 45 testing fmt and escj in
attributes.

* README.md: Added to notes on differences between
TL-WHO and CL-WHO.

3 files changed, 24 insertions, 7 deletions

diff --git a/README.md b/README.md
index 12bb321..3ef41c6 100644
--- a/README.md
+++ b/README.md
@@ -195,6 +195,12 @@ Here are the differences to be aware of:
 *   TL-WHO's `esc` accepts arguments which are not strings. They
     are turned to a string using `tostringp`, and HTML-escaped.
 
+*   TL-WHO allows `fmt` as well as `escj` to be used to calculate attributes.
+    These local macros have alternative definitions when used in attributes.
+    The remaining local macros don't make sense in attributes, and make
+    a mess of the output if used; unlike CL-WHO, TL-WHO warns when they
+    are used in attributes.
+
 Additionally, users (of CL-WHO and TL-WHO alike) are advised to watch for the
 following issue: the CL-WHO documentation is not accurately maintained and
 makes some references to material that no longer exists in CL-WHO, such as the
diff --git a/test/simple.tl b/test/simple.tl
index 3ed4685..4dc5b88 100644
--- a/test/simple.tl
+++ b/test/simple.tl
@@ -453,9 +453,9 @@
 ;;; 41
 ;;; Test that warning is produced when any of the WHO local macros are used in
 ;;; an Lisp expression that calculates an attribute
-(each ((sym '(htm noesc-fmt fmt esc escq escj str)))
+(each ((sym '(htm noesc-fmt esc escq str)))
   (test (catch
-          (eval '(progn
+          (eval ^(progn
                    (with-html-output-to-string (out)
                      (:foo :attr (,sym "abc")))
                    nil))
@@ -480,3 +480,10 @@
 (test (with-html-output-to-string (out)
         (:p (esc 5) (escq 6) (escj 7)))
       "<p>567</p>")
+
+;;; 45
+;;; Test that we can use fmt and escj on attributes
+(test (with-html-output-to-string (out)
+        (:div :span (fmt "~a&" 42)
+              :color (escj "</script>")))
+      "<div span='42&amp;' color='&lt;\\/script&gt;'></div>")
diff --git a/who.tl b/who.tl
index 8ac2ebc..3817e43 100644
--- a/who.tl
+++ b/who.tl
@@ -88,11 +88,15 @@
 (defun attr-warning-macrolet (form)
   (with-gensyms (warn)
     ^(macrolet ((,warn (f . rest)
-                  ^(compile-warning ,f
-                                    "not recommended in attribute expr")))
-       (macrolet ,(collect-each ((sym '(htm noesc-fmt fmt esc escq escj str)))
-                    ^(,sym (:form f . rest) (,warn f) f))
-       ,form))))
+                   ^(compile-warning ,f
+                                     "not recommended in attribute expr")))
+       (macrolet ((fmt (. args)
+                    ^(usr:fmt ,*args))
+                  (escj (thing)
+                    ^[(tojson (tostringp ,thing)) 1..-1])
+                  ,*(collect-each ((sym '(htm noesc-fmt esc escq str)))
+                      ^(,sym (:form f . rest) (,warn f) f)))
+         ,form))))
 
 ;; Helper function for convert-tag-to-string-list which converts the
 ;; alist attr-list of attributes into a list of strings and/or Lisp