Re: Checking existance of global variable in function?

[Etienne Grossmann]

  Hi Volker,

what about testing whether graphdir is a string, as in:

function [out] = plotinit (eps, file, gnuplotfile)
global graphdir
if (exist('graphdir') ~= 0)
  if ~ischar(graphdir), graphdir = ''; end
  graphdir=[graphdir '']

Hth,

  Etienne

PS: You are appending an empty string to graphdir?

On Sun, Jul 16, 2006 at 08:10:21PM +1200, Volker Kuhlmann wrote:
# I'm trying to check a global variable inside a function file. This
# construction:
# 
# function [out] = plotinit (eps, file, gnuplotfile)
# global graphdir
# if (exist('graphdir') ~= 0)
#     graphdir=[graphdir '']
# 
# produces
# warning: implicit conversion from matrix to string
# on the first access to graphdir. exist() always returns 1, caused by the
# global declaration in the function file. Obviously this global
# declaration can't be removed, but I don't see a way to test inside a
# function whether a global variable has been set, without causing a
# warning.
# 
# Is this a bug, meant to be impossible, or am I thick?
# 
# GNU Octave, version 2.1.72 (x86_64-suse-linux).
# 
# Thanks,
# 
# Volker
# 
# -- 
# Volker Kuhlmann                       is list0570 with the domain in header
# http://volker.dnsalias.net/   Please do not CC list postings to me.

-- 
Etienne Grossmann ------ http://www.cs.uky.edu/~etienne