[Jmol-developers] Hash key test

[Rolf H. <rh...@fl...>]

Hi Bob and others,

as far as I know there is currently no fully reliable test available 
that could tell if a specific hash key is already used.

The 'type' function returns "string" if a hash key is not used.
But it also returns "string" if it is used and the value is a string 
value. The problem is that you can't distinguish  between a defined key 
with an empty string value and an undefined key.

It's clear that a change in the behaviour of the type function could 
break existing scripts. So this shouldn't be done.
But maybe an option could be added for testing hash keys (and maybe also 
other array elements). And with this option 'type' would return either 
"undef" or the actual type of the value if it is defined.

Regards,
Rolf
-- 

Rolf Huehne
Postdoc

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