Re: Parallel text on two pages

[Valeriy E. Ushakov]

Well, I just thought it's a good example to show @NotRevealed in
action because of the regular and straightforward pattern this example
exhibits.

On Tue, Aug 21, 2001 at 06:36:52 +0400, Valeriy E. Ushakov wrote:

>     def @Bilingual
>     {
>       3i @Wide @EnPlace ||1i 3i @Wide @DePlace @NotRevealed
>       // @Bilingual
>     }

Let's consider this definition but with @NotRevealed omitted.
What happens when Lout encounters:

    @Bilingual
    
    // @En { ... }
    // @De { ... }

When Lout encounters @Bilingual it just lazily leaves it unexpanded.
Then when it hits @En it starts a search for @EnPlace and it expands
@Bilingual one time to get (omitting gaps etc):

       @EnPlace || @DePlace
    // @Bilingual  # <- @DePlace is visible

Now when Lout hits @De it will search for @DePlace and it will find it
in the yet unexpanded @Bilingual!  So the result will look like


        en en en en en en
        en en en en en en 
                            de de de de de de
                            de de de de de de

That's where @NotRevealed comes to rescue.  With @NotRevealed in place

       @EnPlace || @DePlace
    // @Bilingual  # <- @DePlace is not wisible

the @DePlace in the unexpanded @Bilingual is, well, not revealed - so
when Lout searches for a preceding @DePlace for @De it won't consider
the unexpanded @Bilingual and @De will be sent to the first @DePlace
producing the desired result.

SY, Uwe
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