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  1. #1
    Super Member Bill Tillman's Avatar
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    Oct 2008
    Miami, FL

    Default What's With QUOTE in the Array

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    Some other developers here are sending some variables with values into the project I'm working on from C#.NET code. It looks simple but something I did not expect is happening.

    (setq the_array '('(1 "R" 0 1) '(1 "L" 0 1) '(0 "L" 0 1) '(0 "R" 0 1) '(1 "R" 1 1) '(1 "L" 1 1)))
    If I examine the value of this variable called the_array it will show this:
    ((QUOTE (1 "R" 0 1)) (QUOTE (1 "L" 0 1)) (QUOTE (0 "L" 0 1)) (QUOTE (0 "R" 0 1)) (QUOTE (1 "R" 1 1)) (QUOTE (1 "L" 1 1)))
    I wasn't expecting the word "QUOTE" to show up in the array. I'm going to parse this text to do some drawing tasks so just deleting this text from the string I think I can handle. I'd like to know why it shows up in the first place. I think this guy's attempt to form a list of lists is not quite right.

    By removing the leading apostrophes I able to get the "QUOTE" text out of the value, but I have to admit I wasn't expecting this to happen. Nor were the other developers. And to be honest, I don't really need the " " around the text items in this either. So I'm going to change their input slightly to make it easier to parse this list of lists.
    It's deja vu, all over again.

  2. #2
    Quantum Mechanic Lee Mac's Avatar
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    AutoCAD 2018
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    Aug 2008
    London, England


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    The apostrophe or single quote is a shorthand equivalent for the AutoLISP quote function, therefore, by quoting a list which contains single quotes, you will see the AutoLISP quote function appear as the quoted list is a literal expression and hence is not evaluated. This is no different to quoting a list containing any other AutoLISP function or symbol. Since the entire list is already quoted as a literal expression, the quotes within the list are redundant - see here for more information.
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