Hi Mohammad, > Is it possible to use this operator for checking if the parameter has been > passed to a macro or not!
Sadly not. One might hope this would work: \define macro(param) I'm a macro. Param is <$list filter="[[__param__]!is[variable]]">not</$list> provided \end <<macro param:provided>> <<macro>> But in fact, the “__param__” variable is defined whether or not a parameter value is provided. It may be possible to tweak things so that this trick works, I’ll give it some more thought. Best wishes Jeremy > > --Mohammad > > On Tuesday, February 26, 2019 at 12:25:58 AM UTC+3:30, Jeremy Ruston wrote: > Hi David > > Try: > > [[VAR_NAME]] +[is[variable]addsuffix[ is a variable]] ~[[Undefined variable > or macro 'VAR_NAME']] > > [[currentTiddler]] +[is[variable]addsuffix[ is a variable]] ~[[Undefined > variable or macro ‘currentTiddler']] > > You can try out these examples in the “filter” tab of advanced search in the > prerelease: > > https://tiddlywiki.com/prerelease/#%24%3A%2FAdvancedSearch > <https://tiddlywiki.com/prerelease/#$:/AdvancedSearch> > > Best wishes > > Jeremy. > >> On 25 Feb 2019, at 20:49, David Nebauer <davidn...@ <>gmail.com >> <http://gmail.com/>> wrote: >> >> Thanks, Jeremy. For future reference, would you mind showing how that >> subfilter could be used to test for the existence of a particular variable >> or macro, say 'VAR_NAME', and display the text "Undefined variable or macro >> 'VAR_NAME'" if it is not found. >> >> -David >> >> On Monday, 25 February 2019 22:39:23 UTC+9:30, Jeremy Ruston wrote: >> Hi David >> >> I think you’re right: there is no way to test for the existence of a >> variable whose value is blank. I’ve added an [is[variable]] subfilter >> operator for v5.1.20 to address this: >> >> https://github.com/Jermolene/TiddlyWiki5/commit/36e76429b1a1d4638374d513430393db5693b932 >> >> <https://github.com/Jermolene/TiddlyWiki5/commit/36e76429b1a1d4638374d513430393db5693b932> >> >> Best wishes >> >> Jeremy. >> >> >>> On 25 Feb 2019, at 12:34, David Nebauer <davidn...@ <>gmail.com >>> <http://gmail.com/>> wrote: >>> >>> As I understand it, if you attempt to call an undefined macro the call >>> fails silently, with nothing displaying in the tiddler to alert users. This >>> occurs regardless of the calling method, i.e., >>> >>> <<not-a-real-macro>> >>> or >>> <$macrocall $name="not-a-real-macro"/> >>> >>> Is there a technique for checking whether a macro is defined, and >>> displaying a message in the tiddler if the macro is not defined? >>> >>> Ideally, the test would not just check for output from the macro, since >>> there might be valid circumstances where a macro produces no output. >>> >>> -David >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "TiddlyWiki" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to tiddlywiki+...@ <>googlegroups. <http://googlegroups.com/>com >>> <http://googlegroups.com/>. >>> To post to this group, send email to tiddl...@ <>googlegroups.com >>> <http://googlegroups.com/>. >>> Visit this group at https://groups.google.com/group/tiddlywiki >>> <https://groups.google.com/group/tiddlywiki>. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/tiddlywiki/1ecc0c93-5932-41bb-9634-3eca9daf26c1%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/tiddlywiki/1ecc0c93-5932-41bb-9634-3eca9daf26c1%40googlegroups.com?utm_medium=email&utm_source=footer>. >>> For more options, visit https://groups.google.com/d/optout >>> <https://groups.google.com/d/optout>. >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "TiddlyWiki" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to tiddlywiki+...@ <>googlegroups.com <http://googlegroups.com/>. >> To post to this group, send email to tiddl...@ <>googlegroups.com >> <http://googlegroups.com/>. >> Visit this group at https://groups.google.com/group/tiddlywiki >> <https://groups.google.com/group/tiddlywiki>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/tiddlywiki/49d883c4-f2f7-434b-aaf7-5b1f0d21a29b%40googlegroups.com >> >> <https://groups.google.com/d/msgid/tiddlywiki/49d883c4-f2f7-434b-aaf7-5b1f0d21a29b%40googlegroups.com?utm_medium=email&utm_source=footer>. >> For more options, visit https://groups.google.com/d/optout >> <https://groups.google.com/d/optout>. > > > -- > You received this message because you are subscribed to the Google Groups > "TiddlyWiki" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to tiddlywiki+unsubscr...@googlegroups.com > <mailto:tiddlywiki+unsubscr...@googlegroups.com>. > To post to this group, send email to tiddlywiki@googlegroups.com > <mailto:tiddlywiki@googlegroups.com>. > Visit this group at https://groups.google.com/group/tiddlywiki > <https://groups.google.com/group/tiddlywiki>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/tiddlywiki/19918c87-0d56-4ecf-b057-4aff3147a724%40googlegroups.com > > <https://groups.google.com/d/msgid/tiddlywiki/19918c87-0d56-4ecf-b057-4aff3147a724%40googlegroups.com?utm_medium=email&utm_source=footer>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. 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