isdef

checks variable existence

Calling Sequence

isdef(name [,where])

Arguments

:name a character string : :where an optional character string with default value ‘all’ :

Description

isdef(name) returns %T if the variable named name exists and %F otherwise.

Caveats: a function which uses isdef may return a result which depends on the environment!

isdef(name,’local’) returns %T if the variable named name exists in the local environment of the current function and %F otherwise.

isdef(name,’nolocal’) returns %T if the variable named name exists in the full calling environment (including the global level) of the current function and %F otherwise.

Examples

A=1;
isdef('A')
clear A
isdef('A')

function level1()
  function level2()
    `disp`_(isdef("a","all"));
    `disp`_(isdef("a","local"));
    `disp`_(isdef("a","nolocal"));
  endfunction
  level2()
endfunction
function go()
  a=1;
  level1()
endfunction
go()

See Also

• exists checks variable existence
• isglobal check if a variable is global
• whereis name of library containing a function
• type Returns the type of a variable
• typeof object type
• clear kills variables