buflist optimization: create variables before updating an item

[pascalpoitras]

Feature description

There is a lot of evaluation in my buflist that gives the same result no matter the buffer. I wonder if it would be a great idea to save the result of theses expressions in variables before updating a buflist item. Then we could use these variables in the buflist.format.* options.

For example, we could use an option with the same format as a regex option for triggers

/set buflist.preformat "/.*/${if:${plugins.var.something}!=?${plugins.var.something}:${if:${plugins.var.something_else}!=?${plugins.var.something_else}:white}}/my_fg_color"

then we could use ${my_fg_color} in place of this more complex evaluation (evaluating just one variable instead of four). This is of course an example, My expression are a lot more complex and would benefit a lot from that

So when a buflist is refresh

1. evaluate buflist.preformat (in lack of a better name)
2. update the item

[pascalpoitras]

not needed anymore, I have created a modifier and pass it the redundant part and it works perfectly and make the buflist faster