On 2014-03-05 03:24, Hans Hagen wrote:
> On 3/5/2014 5:45 AM, Rik Kabel wrote:
>> I am trying to strip all leading and trailing whitespace from a string.
>> I have tried two methods, neither of which is satisfactory.
>>
>> The first method uses \ignorespaces and \removeunwantedspaces. This
>> fails to strip leading and trailing newlines.
>>
>> The second method uses the Lua string.strip function. The wiki 
>> description:
>>
>>     Yields string with leading and trailing whitespace (spaces,
>>     horizontal and vertical tabs, newlines) removed
>>
>> suggests that this should do what I want, but I find that it removes
>> internal whitespace as well as the leading and trailing whitespace.
>>
>> Can somebody suggest a better way of doing this?
>>
>> The following code demonstrates the problem:
>>
>>     % macros=mkvi
>>     \starttexdefinition StringStrip #STRING
>>        \startluacode
>>          context(string.strip([==[#STRING]==]))
>>        \stopluacode
>>     \stoptexdefinition
>>     \long\def\test{
>>
>>     This is a test. \quad
>>
>>     And it has an unexpected result.
>>
>>     With \tex{ignorespaces} and \tex{removeunwantedspaces}, the
>>     newlines remain.
>>
>>     With Lua {\tt string.strip}, the \tex{quad} at the end of a
>>     paragraph is preserved,    but the other internal whitespace
>>     (including newlines) is gone!
>>
>>     }
>>     \starttext
>>     \subject{ignorespaces and removeunwantedspaces}
>>     ¦\ignorespaces\test\removeunwantedspaces¦
>>
>>     \subject{Lua string.strip}
>>     ¦\StringStrip{\test}¦
>>     \stoptext
>
> striplong
>

It would be nice if striplong worked, but the example fails when 
string.striplong is used in place of string.strip. The log says:

    ! LuaTeX error [string "\directlua "]:1: attempt to call field
    'striplong' (a nil value)
    stack traceback:
         [string "\directlua "]:1: in main chunk.

Is the format of the call different than shown in the wiki, or is a 
different mechanism required to quote a potentially long string?

-- 
Rik