[metapost] test for empty text?
metapost at cfraizer.com
Tue May 28 16:28:46 CEST 2013
A great tip. Thanks, Daniel!
I had found a workaround for my immediate need using a mixture of delimited
and undelimited text params and some special delimiters, but this is a
better general solution.
From: Daniel H. Luecking [mailto:luecking at uark.edu]
Sent: Tuesday, May 28, 2013 9:55 AM
To: Colin Fraizer; metapost at tug.org
Subject: RE: [metapost] test for empty text?
Colin Fraizer [metapost at cfraizer.com] wrote:
> - Is there a way to test if the replacement text of a macro
>I have a macro which expands to a color or to empty (0 tokens),
>in which case I want to use "background".
I might make use of the fact that a for-loop ignores empty
items in a list. For example:
def getmycolor (text clr) =
for c = clr,background:
mycolor := c;
When the parameter clr is empty, one should get
mycolor := background
on the first (only) iteration of the loop, but when clr
is an actual color one should get
on the first iteration, and then immediately exit the
I did not test this, but I have done similar things before.
Daniel H. Luecking
Department of Mathematical Sciences
University of Arkansas
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