[IDEA] add second optional reverse operand to sort, nsort and sortcs operators

[saqimtiaz]

While the sort[], nsort[] and sortcs[] operators support use of the ! prefix to reverse the sort order, this cannot be assigned from a variable and requires string concatenation to construct the filter.

It is proposed to introduce a second optional operand that is the equivalent of using the ! prefix. The following two filter expressions would be equivalent:

[all[tiddler]sort[modified],[reverse]]
[all[tiddlers]!sort[modified]]

[Jermolene]

Thanks @saqimtiaz that makes complete sense, but would prevent us from using multiple operands to support multiple sort fields – it sometimes seems like it would be handy to be able to things like [all[tiddlers]sort[type],[modified]]. Of course, the same problem would crop up: it wouldn't be possible to reverse the sort of individual fields in the list.

[Jermolene]

Perhaps a :sort[] filter run prefix would be helpful?

[pmario]

I think, there are even more "sort" operators, that would benefit. eg: sortby doesn't support ! atm, but imo it should.

• sortsub Operator
• sortcs Operator
• sortby Operator
• sortan Operator
• sort Operator
• nsortcs Operator
• nsort Operator

Should it be an optional second operator or should it be a flag: eg: [sort:reverse[modified]] ??

[saqimtiaz]

Perhaps a :sort[] filter run prefix would be helpful?

@Jermolene We do have a :sort filter run prefix, but it does not accommodate the use case of assigning the reverse argument from a variable or text reference. It can however with some creativity be used to sort by multiple fields.

Should it be an optional second operator or should it be a flag: eg: [sort:reverse[modified]]

@pmario that does not meet the need for specifying a reverse sort using a variable or text reference.

[Jermolene]

@Jermolene We do have a :sort filter run prefix, but it does not accommodate the use case of assigning the reverse argument from a variable or text reference. It can however with some creativity be used to sort by multiple fields.

Doh! Of course, thank you.

@pmario that does not meet the need for specifying a reverse sort using a variable or text reference.

As a strawman, we could extend parseFilterOperation() to recognise alternate forms of the prefix. Along with the existing !, we could support <!var> as a way to indicate that the prefix should be taken from the specified variable.

So, we'd have:

[<!myvar>sort[modified]]

Or:

[<!myvar>sort<anothervar>]

[saqimtiaz]

As a strawman, we could extend parseFilterOperation() to recognise alternate forms of the prefix. Along with the existing !, we could support <!var> as a way to indicate that the prefix should be taken from the specified variable.

That could be an option. I am also considering the viability of extending filter suffixes to support variables, though we need to consider whether that might get too confusing:

[all[tiddlers]sort:<sortvar>[modified]]

[saqimtiaz]

The advantage of an alternative form of ! that can be specified by a variable is that all operators that already support the prefix can take advantage of it. I wonder if we can find a more intuitive syntax though, <!var> could be confused with title<!var>.

[kookma]

[all[tiddlers]sort:<sortvar>[modified]]

This seems more native in comparison to other suggested forms!

[joshuafontany]

Would it make sense to extend the reverse[] Operator & call that out in the docs?

reverse<var>,<condition> or reverse{!!reverse-list},[yes]?

[Jermolene]

Would it make sense to extend the reverse[] Operator & call that out in the docs?

reverse<var>,<condition> or reverse{!!reverse-list},[yes]?

Hi @joshuafontany is the goal to be able to turn on or off reversing via a variable/transclusion?

[joshuafontany]

Would it make sense to extend the reverse[] Operator & call that out in the docs?
reverse<var>,<condition> or reverse{!!reverse-list},[yes]?

Hi @joshuafontany is the goal to be able to turn on or off reversing via a variable/transclusion?

By my reading of @saqimtiaz 's post, yes. It is desirable to control sort order reversal via a contextual reference (var, transclusion). It makes more sense to me to use the reverse operator (which currently has no parameters).

[saqimtiaz]

@joshuafontany that is a good idea and worth considering as another improvement.

However, having a way to trigger the ! prefix for a filter operator via a variable/transclusion is still desirable as well. Adding such a possibility to the filter syntax would mean that all operators that support the ! flag would be able to trigger it via variable/transclusion.

Consider also that in the case of sorting large lists, performance is better to sort in the correct order, as opposed to sorting and then reversing the list.