[IDEA] Add macro operator

[Leilei332]

The current implementation of using macros in filters isn't good enough:

<$list filter="[<mymacro param:'value'>]">
...
</$list>

It isn't able to use variables or textreference as a parameter of the macro. I think we had better introduce a macro operator so that variables and textreference can be used as parameter (like the function operator). For example

<$list filter="[macro[mymacro],[value]]">
...
</$list>

<$let template="DDth MMM YYYY">
<!-- variables and textreference are allowed -->
{{{ [macro[now],<template>] }}}
{{{ [macro[now],{$:/config/NewJournal/Title}] }}}
</$let>

[pmario]

It would be sensible to name it procedure or proc and allow \procedure definitions and may be \defines too.

The most generic way would be transclude[variable],[param1] and so on. But we already have a transcludes operator so this will be very error prone.

[Leilei332]

As is described in docs:

Procedure calls can be used in filters. The text is not wikified which again means that the parameters will be ignored.

So it isn't encouraged to use procedure with parameters in filters. IMO the operator should not support macros or procedures defined in tiddlers, it only makes sense to support javascript macros in filters.

[Jermolene]

Hi @Leilei332 might another possibility be to update the existing function operator to be able to work with JS macros? At the moment, [function[now]] is broken.

[Leilei332]

If we decided to extend the function operator to support javascript macros, we need to deal with the conflict of functions defined in tiddlers and javascript macros:

1. Disallow functions which has the same name as a core javascript macro
2. Allow overriding javascript macros

[Jermolene]

Hi @Leilei332 I guess we already have the same conflict between functions and JS macros when using the <<name>> syntax, so perhaps we can make things consistent.

[Leilei332]

I think we may add some documention on overriding core javascript macros. (Perhaps the name Javascript macros can be changed to Javascript functions)

[Jermolene]

Hi @Leilei332 thank you, that is an excellent idea