Re: [NTG-context] metapost code fails to work in mkiv

3 Dec 2008

      On Wed, Dec 3, 2008 at 4:25 PM, Hans Hagen  wrote:
...
Mojca Miklavec wrote:
...
Hello,
A while back I wrote this dirty code (read as: hack) in attachment
that allows multiple optional parameters in metapost functions, for
example:
draw_text("text");
draw_text(angle(30),"text");
draw_text(angle(30),align(right),"text");
draw_text(align(center),"text");
The code compiles fine with mkii, but not with mkiv. I would be
grateful for any hints about how to fix this.
I get the error:
mplib | mp terminal: ! Missing `,' has been inserted.
<to be read again>
                   ,
textext->...etextext(SUFFIX2)(rawtextext((EXPR3)),
                                                  origin)else:thetextext(SUF...
dummy->begingroup(TEXT2)
                        endgroup
gp_put_text->...tt)=tt.enddef;pict:=dummy((TEXT1))
                                                  ;let,=@;endgroup;draw(gp_t...
<*> ...m, 1cm), angle(30), textext.drt("rotated"))
                                                  ; ;
! An expression can't begin with `;'.
<inserted text>
                0
<to be read again>
                   ,
textext->...etextext(SUFFIX2)(rawtextext((EXPR3)),
                                                  origin)else:thetextext(SUF...
Thanks a lot,
    Mojca
(The code is taken out of
http://dl.contextgarden.net/modules/t-gnuplot/metapost/context/third/gnuplot...
and I'm slowly plucking up my courage to port the code to mkiv.)
\startMPcode
    def fuzzy(expr a, b, c) =
        draw image(
            draw textext(c) ;
            currentpicture := currentpicture rotatedaround(center
currentpicture,b) shifted a ;
        ) ;
    enddef ;
fuzzy((1cm,1cm), 30, "rotated") ;
\stopMPcode
But what if I wanted the angle to be an optional parameter? (More in
the sense that if I decide to add some more parameters later, the old
code would still work.)

Is there any special reason why the old code doesn't work on mkiv?
I have found one possible explanation, though I'm not sure about that:

This works:

picture a; a := \sometxt{rotated};
gp_put_text((1cm, 1cm), angle(30), a);

but this doesn't:

gp_put_text((1cm, 1cm), angle(30), \sometxt{rotated});

What does metapost see in mkiv when one puts \sometxt there? Maybe
that explains the problem.

Mojca