Re: [PATCH] pretty: Add %(trailer:X) to display single trailer

[Anders Waldenborg <anders@0x63.nu>]

Jeff King writes:

> On the other hand, if the rule were not "this affects the next
> placeholder" but had a true ending mark, then we could make a real
> parse-tree out of it, and format chunks of placeholders. E.g.:
>
>   %(format:lpad=30,filename)%(subject) %(authordate)%(end)
>
> would pad and format the whole string with two placeholders. I know that
> going down this road eventually involves reinventing XML, but I think
> having an actual tree structure may not be an unreasonable thing to
> shoot for.

Yes. I'm thinking that with [] for formatting specifiers and () for
placeholders, {} would be available for nesting. E.g:

   %[lpad=30,mangle]{%(subject) %ad%}


> My main concern for now is to avoid introducing new
> syntax that we'll be stuck with forever, even though it may later become
> redundant (or worse, create parsing ambiguities).

Agreed.

I'm planning to work on the initial "trailer:key=" part later this
week. Maybe I can play around with different formatting options and see
how it affects the parser.