Hans Hagen via ntg-context schrieb am 02.08.2021 um 17:17:
On 8/2/2021 4:43 PM, Aditya Mahajan via ntg-context wrote:
On Mon, 2 Aug 2021, Benjamin Buchmuller via ntg-context wrote:
Hi,
How can I check if a buffer or block has content (or is empty)
before a \useblocks or \getbuffer statement?
I would like to typeset a headline only if the buffer/block has been
used in a particular section and want to avoid headlines with empty
sections.
There may be more efficient ways to do it (since buffers are stored
at the lua end), but you can always do \doiftextelse(\getbuffer[...]}
to test it buffer creates any output.
indeed you know there is a way ...
\starttext
\startbuffer[test]
test
\stopbuffer
\doifelsebuffer{test} {YES} {NOP}
\permanent\protected\def\doifelsebuffercontent#1%
{\doifelse{\luaexpr{(string.strip(buffers.getcontent("#1")) ~= ""
and "yes")}}{yes}}
\startbuffer[test]
\stopbuffer
\doifelsebuffercontent{test} {YES} {NOP}
\startbuffer[test]
\stopbuffer
\doifelsebuffercontent{test} {YES} {NOP}
\stoptext
if we can agree on a proper name then i can add a (more efficient)
\doifelse...
To follow the existing commands we can use
\doifelsebufferempty
\doifelsebuffersomething
\doifelsebuffernothing
or (we already have \xmldoif... and \btxdoif...)
\bufferdoifelseempty
\bufferdoifelsesomething
\bufferdoifelsenothing
Wolfgang
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