[Therion] scaling a line thickness in Metapost

[Tarquin Wilton-Jones]

> Apparently you can use "save"
> within a begingroup section to make variables local, so I am playing
> with that right now to see if I can work out how to use it.


Easy enough:

def l_u_foo
  begingroup; %allow local variables to work
    save scale, bar, baz; %declare local variables
    string scale;
    if known ATTR_scale:
      scale:=ATTR_scale;
    else:
      scale:="m";
    fi;
    ...
  endgroup;
enddef;

I tried using vardef instead, but couldn't get it to work.

"save" actually temporarily saves the existing (global) value of a
variable, then restores is after the endgroup. But it has the effect of
creating a local variable.