Thread-Topic: Passing a dictionary to, for example,  the TOC entry formatter
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Date:         Tue, 24 Nov 2009 13:58:09 +0000
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From: "J.Fine" <J.Fine@OPEN.AC.UK>
Subject: Re: Passing a dictionary to, for example,  the TOC entry formatter
To: LATEX-L@LISTSERV.UNI-HEIDELBERG.DE
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Status: R

Joseph write:

> > Frank:  I don't understand what you mean by 'the overhead of
> processing'.)
>
> I assume Frank was thinking that we wouldn't want to do everything in a
> dictionary manner as some arguments are always needed, and so something
> like:
>
> \def\foo@bar#1#2{%
>   Title:   #1\\%
>   Name:    \DictionaryLookup{#2}{name}\\%
>   Address: \DictionaryLookup{#2}{address}\\%
> }
>
> will be faster for the explicitly passed #1 than the dictionary items,
> independent of how the dictionary is implemented. (I'd assume that a
> dictionary would be a single data structure: I'd probably do it as an
> expl3 properly list, and then recovering data would certainly add some
> processing overhead. However, even a csname expansion as you outline is
> an additional overhead compared to an explicitly passed value.)

The overhead you point to is slight, and there are worse offenders (such as the LaTeX3 programming language itself).

I also suspect that if you do the tests I think you'll find
  \expandafter\def\csname aa.bb\endcsname{A longish piece of text}
  \def\mymacro #1{\csname #1.bb\endcsname
  \mymacro{aa}
will be quicker than
  \mymacro{A longish piece of text}
because of the reduced churning of tokens.  But I could be wrong.

Your revision of my
    #1{name}
to
    \DictionaryLookup{#2}{name}
I strongly disagree with.  You've taken something simple that works, and changed it to something that is broken (because it assumes that all maps will be dictionaries).

Jonathan


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