On 21 okt. 2011, at 17:13, Peter Rolf wrote:
Am 21.10.2011 15:05, schrieb Hans van der Meer:
I cannot find the answer to the following question in Knuth's Metafont book. The following definition with a trailing text argument:
def mydef (expr a, b, c) text modifier = if
: Have you already tried
if modifier = "" :
else: fi enddef;
I tried it now, but it doesn't work. Something like if(TEXT4) ="":;fi in the error log. No, Metapost is not happy with this construct.
How can I do the switch on an empty or nonempty modifier argument? It is not a string because calling its length fails with an error. I must do the switch, because "fill modifier" with an empty "modifier" gives horrible results.
Usage would be calls like: mydef(1,2,3) withcolor green; % with modifier text mydef(1,2,3); % without modifier text
Thanks in advance. Hans van der Meer