How to put the same logic of different pug files into one place?

I have three pug files: a.pug, b.pug and c.pug:

a.pug:

block header
  style
    .
      body {...}
    if (option.a == 'yes')
      include a.css
    if (option.b == 'yes')
      include b.css
  #main-a
    p This is page A ....

b.pug:

block header
  style
    .
      body {...}
    if (option.a == 'yes')
      include a.css
    if (option.b == 'yes')
      include b.css
  #main-b
    p This is page B ....

c.pug:

block header
  style
    .
      body {...}
    if (option.a == 'yes')
      include a.css
    if (option.b == 'yes')
      include b.css
  #main-c
    p This is page C ....

They share the same logic under the style block:

    if (option.a == 'yes')
      include a.css
    if (option.b == 'yes')
      include b.css

Is there any way to make the logic in a specific file so I can include it from my three pug files later? Otherwise, if I need to modify the logic, like adding a new line like:

    if (option.c == 'yes')
      include c.css

I have to make changes to all three pug files.

Thanks for any tips.

Solution

You can put the logic in an external file. The variables can be processed from there as well.

a.pug, b.pug, c.pug, ...

block header
  include styles.pug
  #main-a
    p This is page ....

styles.pug

style.
  body {...}
  if (option.a == 'yes')
    include a.css
  if (option.b == 'yes')
    include b.css