Hello David, Yes, the new subfilter operator can check if a macro/variable is defined (exist) or not! It works in TW5.1.20pr.
Example \define VAR_NAME() This is a test macro <$list filter="[[VAR_NAME]] +[is[variable]addsuffix[ is a variable]] ~[[Undefined variable or macro 'VAR_NAME']]"> <<currentTiddler>> </$list> <$list filter="[[VAR_NAME2]] +[is[variable]addsuffix[ is a variable]] ~[[Undefined variable or macro 'VAR_NAME2']]"> <<currentTiddler>> </$list> Results: VAR_NAME is a variable Undefined variable or macro 'VAR_NAME2' So, it works. Note that, VAR_NAME2 is not existed! --Mohammad On Tuesday, February 26, 2019 at 10:19:06 PM UTC+3:30, David Nebauer wrote: > > I'm glad my question has led to something useful for others. > Unfortunately, my original question has not been answered. Is there any way > to use Jeremy's new subfilter to display an error message if a specified > macro is undefined? (Thanks, Mal, for your efforts.) > > Alternately, if it is still not possible, even with the new subfilter, I'd > appreciate having that confirmed. > > David. > > On Wed, 27 Feb 2019 at 00:31, Mohammad <mohammad...@gmail.com > <javascript:>> wrote: > >> Thanks for clarification! >> >> --Mohammad >> >> On Tuesday, February 26, 2019 at 3:38:07 PM UTC+3:30, Jeremy Ruston wrote: >>> >>> Hi Mohammad >>> >>> The reason that we don’t use the “[<macro>]” formulation here is because >>> we don’t want to retrieve the value of the macro, we want to get its name >>> as a string. >>> >>> Best wishes >>> >>> Jeremy >>> >>> On 26 Feb 2019, at 11:57, Mohammad <mohammad...@gmail.com> wrote: >>> >>> Hello again Jeremy, >>> >>> Look at below code >>> >>> \define macro(VAR_NAME) >>> test >>> \end >>> >>> <$list filter="[[macro]] +[is[variable]addsuffix[ is a variable]] >>> ~[[Undefined variable or macro 'VAR_NAME']]"> >>> <<currentTiddler>> >>> </$list> >>> >>> >>> Why the syntax needs variable like Tiddler title, I expect to have macro >>> or variable as below >>> >>> >>> <$list filter="[<macro>] +[is[variable]addsuffix[ is a variable]] >>> ~[[Undefined variable or macro 'VAR_NAME']]"> >>> <<currentTiddler>> >>> </$list> >>> >>> I mean, using angle bracket. >>> >>> --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/#$:/AdvancedSearch> >>>> >>>> Best wishes >>>> >>>> Jeremy. >>>> >>>> On 25 Feb 2019, at 20:49, David Nebauer <davidn...@gmail.com> wrote: >>>> >>>> Thanks, Jeremy. For future reference, would you mind showing how that >>>> subfilter could be used to test for the existence of a particular variable >>>> or macro, say 'VAR_NAME', and display the text "Undefined variable or >>>> macro >>>> 'VAR_NAME'" if it is not found. >>>> >>>> -David >>>> >>>> On Monday, 25 February 2019 22:39:23 UTC+9:30, Jeremy Ruston wrote: >>>>> >>>>> Hi David >>>>> >>>>> I think you’re right: there is no way to test for the existence of a >>>>> variable whose value is blank. I’ve added an [is[variable]] subfilter >>>>> operator for v5.1.20 to address this: >>>>> >>>>> >>>>> https://github.com/Jermolene/TiddlyWiki5/commit/36e76429b1a1d4638374d513430393db5693b932 >>>>> >>>>> Best wishes >>>>> >>>>> Jeremy. >>>>> >>>>> >>>>> On 25 Feb 2019, at 12:34, David Nebauer <davidn...@gmail.com> wrote: >>>>> >>>>> As I understand it, if you attempt to call an undefined macro the call >>>>> fails silently, with nothing displaying in the tiddler to alert users. >>>>> This >>>>> occurs regardless of the calling method, i.e., >>>>> >>>>> <<not-a-real-macro>> >>>>> or >>>>> <$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. >>>>> Visit this group at 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. >>>>> >>>>> >>>>> >>>> -- >>>> 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. >>>> To post to this group, send email to tiddl...@googlegroups.com. >>>> Visit this group at 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. >>>> >>>> >>>> >>> -- >>> 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. >>> To post to this group, send email to tiddl...@googlegroups.com. >>> Visit this group at https://groups.google.com/group/tiddlywiki. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/tiddlywiki/6c5462a8-99ad-4133-86f3-199b3ac66737%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/tiddlywiki/6c5462a8-99ad-4133-86f3-199b3ac66737%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> For more options, visit https://groups.google.com/d/optout. >>> >>> >>> -- >> You received this message because you are subscribed to a topic in the >> Google Groups "TiddlyWiki" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/tiddlywiki/4rEuAWc4EpM/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> tiddlywiki+...@googlegroups.com <javascript:>. >> To post to this group, send email to tiddl...@googlegroups.com >> <javascript:>. >> Visit this group at https://groups.google.com/group/tiddlywiki. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/tiddlywiki/4580fe7a-9855-428b-8246-2ea56bcc2fae%40googlegroups.com >> >> <https://groups.google.com/d/msgid/tiddlywiki/4580fe7a-9855-428b-8246-2ea56bcc2fae%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > -- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. 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