Make default margin values depend on paper size.

Make default margin values depend on paper size.

[Carl, 2009-09-07 16:37:48]

I like what you've done.

I've put a couple of comments in.  They are not mandatory, but just for your
consideration.

Carl

http://codereview.appspot.com/115065/diff/1001/1003
File scm/paper.scm (right):

http://codereview.appspot.com/115065/diff/1001/1003#newcode220
Line 220: (scaleable-values (list
I think it would be better to use symbols, rather than strings, here.  I don't
have a strong preference for this; obviously these strings are only used locally
to define symbols later on.

But the things they stand for are symbols elsewhere in the code, so I'd prefer
using symbols here.

http://codereview.appspot.com/115065/diff/1001/1003#newcode221
Line 221: (cons "left-margin" w)
I think you could alternatively do (either with symbols or strings):

(scaleable-values `((left-margin . ,w)
                                    (right-margin . ,w)
                                    (top-margin . ,h)
                                    ...
                                    (short-indent . ,w))

http://codereview.appspot.com/115065/diff/1001/1003#newcode232
Line 232: ((value-symbol (string->symbol (string-append (car value)
"-default")))
I you were using symbols, you'd have

(value-symbol 
  (string->symbol (string-append
                       (symbol->string (car value))
                       "-default")))

http://codereview.appspot.com/115065/diff/1001/1003#newcode244
Line 244: (module-define! m 'left-margin-default-scaled (cdr (assoc
"left-margin" scaled-values)))
This is a potential error waiting to cause problems for  a user.  assoc can
return #f, and (cdr #f) is an error. 

If you use assoc-get, you can supply a default value, e.g.
(module-define! m 'left-margin-default-scaled (assoc-get 'left-margin
scaled-values default-value))

where default-value is whatever the reasonable default value would be if things
somehow got broken.

I realize that you have just built the list here, so you're in control and it
can be argued that this is not necessary.  I'm not demanding this change, just
asking you to consider it.