[texhax] Two problems with \sidx

[Barbara Beeton]

On Tue, 10 May 2011, D. R. Evans wrote:

    I have two issues (using eplain TeX):

    1. If I have the following explicit inline text in my file, it gives no error:
      {\sc nop}\sidx{{\sc nop} gate
    This prints "NOP" in small caps and inserts the text "NOP gate" into the index.

    However, if I define \nop as:
      \def\nop{{\sc nop}\sidx{{\sc nop} gate}}
    Then when the compiler reaches "\nop" in the text, TeX throws an error:
      ! Incomplete \iffalse; all text was ignored after line 1415.

    I don't understand why this happens, nor how to fix it.

can't answer this one quickly; if no one
else answers, i'll try later.

    2. When I place the text inline:
      {\sc nop}\sidx{{\sc nop} gate
    then although the text "NOP gate" appears in the index, it does so *at the
    start* of the index.

this one's easy though ...

    If I look in the *.ind file, it begins:

    ----

    \begin{theindex}

      \item {\sc nop} gate, 21

      \indexspace

      \item BB84, 79

    ----

    So it looks like makeindex is putting the entry in completely the wrong place.

    The *.idx file has the following:
      \indexentry{{\sc nop} gate}{21}
    so my guess is that makeindex is sorting this entry according to either the
    second "{" or the "\", which I suppose makes sense, but I haven't been able
    think of a way around this: any sneakiness I've been able to think of
    begins with "\" and so sorts incorrectly.

makeindex does no real parsing of the lines
in the .idx file until after they're sorted.
it performs a straight ascii sort on the text
provided, so, yes, the sort is on the open
brace, so it goes at the beginning of the .ind
file.

    So how can I force the index entry to appear in the correct place in the
    index?

give it a sort key:

  \sidx{nop gate@{\sc nop} gate}

if you index this (or any multi-word term)
in more than one place, make sure that all
instances in the input are exactly the same;
spacing as well as spelling and tex commands
must be identical, or they'll sort separately,
even though they look the same when the index
is printed out.
						-- bb