[metapost] documentation of length operator

Larry Siebenmann laurent at math.toronto.edu
Wed Mar 7 02:05:50 CET 2007

Hi all,

Stephan Hennig wrote (Sun, 04 Mar 2007 16:13:55 +0100):

 > Hi,
 > although I didn't find anything about that in mpman
 > and mpgraph the length operator is perfectly happy
 > operating on strings:
 > beginfig(1);
 > string s;
 >   s := "MetaPost";
 >   show length(s);
 > endfig;
 > end
 > If this feature is officially supported, it is missing
 > from mpman, that only discusses "length <path
 > primary>".  Mpgraph adds to that only "length <picture
 > primary>".

Thanks for the heads-up Stephan.

The chapter "A Reference Manual" on  
pages 63-- of "mpman.pdf" warns:

A few features are not explained elsewhere and have 
no page number listed. These features exist primarily 
for compatibility with METAFONT and are intended to 
be self-explanatory. Certain other features from 
METAFONT are omitted entirely because they are of 
limited interest to the MetaPost users and/or would 
require long explanations. All of these are 
documented in The METAFONT book [4] as explained in 
Appendix B.

Does anyone here maintain that the above disclaimer
justifies the omission of length of strings from the
above reference manual?  I don't. I believe the
listing for "length" in Table 7 for Operators should
be augmented by addition of "string" and "picture" as
right argument types.

This list is a sign that metapost is alive and
aims to be autonomous. 

Incidentally, it is time that the core language 
features of metapost that were new with "mpgraph.pdf" 
finally appear in the reference manual tables 
mentioned above.  Stephan, perhaps you could 
accellerate the improvement of metapost by preparing 
such reference manual additions. Karl Berry made some 
additions to the documentation not too long ago.  
Include relevant cross-references to the mpgraph 
manual "mpgraph.pdf".


Laurent S.

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