View template filter efficiency

[andrewg_oz]

I’ve been reviewing an older wiki that I recently updated to 5.3.8. It is using several view templates all starting with something like (different tag criteria in each):

<$list filter="[is[current]tag[taggymctagface]]">

I was wondering if that is still best practice? I was thinking that I should change it to something like:

<%if [<currentTiddler>tag[taggymctagface]] %>

I’ve noticed that <currentTiddler> appears to work the same as is[current] and all[current]. Is there a reason to pick one over the others?

[EricShulman]

<currentTiddler> directly retrieves the variable value, while is[current] and all[current] both need to parse the [current] param value before retrieving the variable value. Thus, <currentTiddler> is very slightly more efficient, but not in any way that you will notice for your view template usage.

I prefer using <currentTiddler> since I feel it is semantically much clearer as to what it is doing.

-e

[TW_Tones]

Perhaps the only place you could gain efficiency, is if you move the current enhancements of the viewTemplate into the viewTemplate cascade mechanisms. This is so very dependant on what your existing enhancements do.

• There is a strong argument not to bother unless you face performance problems because the gains may be minimal yet take a lot of effort to implement.

[EricShulman]

The ViewTemplateBody cascade (see $:/ControlPanel > Info > Advanced > Cascades > ViewTemplateBody) is the way to go when you want to completely replace the default tiddler body with alternative content.

However, if your objective is to add extra content to the default tiddler body, then using $:/tags/ViewTemplate with conditional logic (either $list or %if) is significantly easier to understand and implement.

-e

[andrewg_oz]

@EricShulman

I prefer using <currentTiddler> since I feel it is semantically much clearer as to what it is doing.

I agree, that was the feeling I was getting.

@TW_Tones

There is a strong argument not to bother

There doesn’t seem to be opinion of <$list> vs <%if%>, but the latter is clearer. It seems my original thinking was on the right track.

Thanks for the feedback. When working with TiddlyWiki there is so much functionality I’m always wondering if there is some hidden trick or something I’m missing!

[TW_Tones]

@andrewg_oz

I’m always wondering if there is some hidden trick or something I’m missing!

There usually is, but it is not necessary

[Springer]

@andrewg_oz

There doesn’t seem to be opinion of <$list> vs <%if%>, but the latter is clearer. It seems my original thinking was on the right track.

Many of us had our <$list … > habits in place long before the conditional shortcut syntax <% if … %> came into being. And since it ain’t broke, we may not be fixing it until/unless prior work needs refactoring.

For new work, I do prefer <% if %> — especially for the ease of following up with an <% else %>. The <$list> version can lead to awkward surprises if you haven’t usually needed to add limit[1] to the end of the filter… but suddenly a solution that worked fine somewhere else ends up displaying your conditional content once for every tiddler in your wiki.

[EricShulman]

For some more discussion use of older syntax for backward compatibility, see

Some thoughts on backward compatibility

An interesting side note about backward compatibility… The syntax I used in the TiddlyTools/PrintTiddler toolbar button includes \procedure and “substituted attribute values”, which were introduced in v5.3.0 (1st July 2023), and also “conditional shortcut syntax” (<%if ...>), which was introduced in v5.3.2 (13th December 2023). I decided to test TiddlyTools/PrintTiddler by importing it into the various “Beautiful Wikis” posted in the Cafe section. It was then that I noticed that some of these…

[TW_Tones]

@Springer

Many of us had our <$list … > habits in place long before the conditional shortcut syntax <% if … %> came into being. And since it ain’t broke, we may not be fixing it until/unless prior work needs refactoring.

Also I would add to this we tended to use list primarily for listing, but before we had “If conditionals” at most we had the reveal widget, which is unnecessarily complex for many cases, we ALSO used list for conditional display.

Now conditional display can be well served by the if statement, it does not reduce the power of the $list widget, it simply allows it to be used for its primary purpose of listing.

If I were giving advice to someone learning TiddlyWiki I would suggest both are important to the operation of TiddlyWiki and they both deserve your attention.