Using the keyboard modifier variable in actions

#1

Folks,

I am wondering if any one can provide some guidance on the modifier variable in a collection of different usage forms. It will also through light on the issues with actions and when values are “evaluated” eg at button render or on click.

  • I suspect @EricShulman @pmario amongst others, already understand this deeply enough to answer easily.

I have used the modifier variable to detect keyboard modifier keys such as shift, alt and ctrl including normal a few times with success. Then all of a sudden, I started to find it fragile, basically not working for some reason that is not clear to me.

  • I started this Topic to create a Discourse wiki post once I have clarity on this, please help us understand this.
  • Somehow conceptually I though the modifier value was “plucked from the air” and the time the button is clicked. But this does not seem to be the case.

Consider the following

  • Imagine each list has some action widgets within it.
\define button-actions(content)
<$list filter="[<modifier>match[normal]]" variable=nul>

</$list>

<$list filter="[<modifier>match[ctrl]]" variable=nul>

</$list>

<$list filter="[<modifier>match[alt]]" variable=nul>

</$list>

<$list filter="[<modifier>match[shift]]" variable=nul>

</$list>
\end

Now there are a few ways we can call the button-actions from a button or other trigger, note the buttons are numbered for subsequent reference.

<$button actions=<<button-actions param>> >
button 1
</$button>

<$button actions="""<<button-actions param>>""">
button 2
</$button>

<$button>
<<button-body-actions>>
button 3
</$button>

<$button>
<$list filter="[<modifier>match[normal]]" variable=nul>

</$list>

<$list filter="[<modifier>match[ctrl]]" variable=nul>

</$list>

<$list filter="[<modifier>match[alt]]" variable=nul>

</$list>

<$list filter="[<modifier>match[shift]]" variable=nul>

</$list>
button 4
</$button>
  • There is another possibility and that is to embed the modifier conditional list inside the actions="""<$list...""" let us call this button 5

Your feedback greatly appreciated.

#2

That’s the only way you should do it:

<$button actions=<<button-actions>> >
button 1
</$button>

I think the above is best practice and the other examples shouldn’t be used.

Edit: I did remove the param element from the <<button-actions>> macro parameter. …

#3

I have to check but your nominated option is not working for me I belive in part because of the macro being set at button render time.

  • I now realise there are other issues even if the responce to the modifier variable is addressed
#4

Calling button actions with the “actions” parameter is the only way, where the actions are evaluated at click-time. …

If the actions are inside the button widget, you will get problems.

#5

If parameters for actions calls are needed, I think that’s the only option at the moment. … I personally never needed any parameters in button actions.

2 Likes
#6

@EricShulman gave a great explanation on this topic here:

1 Like
#7

I think even in erics post there is a little ambiguity in the difference between actions=<<macroname param>> and actions="""<<macroname param>>""".

Once clear I my mind I will edit and adapt this topic as a guide. As a result I am seaking a deep understanding of this problematic and oft fragile part of tiddlywiki.

I see a need to include the button messages in this as well.