refactor: Rewrite landscape handling PR

* Avoid possible race conditions
* Only set defaults once
* Handle landscape mode on custom paper sizes
* Avoid setting usused variables
* Add code comments for the benefit of other coders and future self

classes/base.lua

@@ -79,8 +79,12 @@ end
 
 function class:setOptions (options)
   options = options or {}
+  -- Classes that add options with dependencies should explicitly handle them, then exempt them from furthur processing.
+  -- The landscape option is handled explicitly before papersize, then the "rest" of options that are not interdependent.
   self.options.landscape = SU.boolean(options.landscape, false)
-  options.papersize = options.papersize or "a4"
+  options.landscape = nil
+  self.options.papersize = options.papersize or "a4"
+  options.papersize = nil
   for option, value in pairs(options) do
     self.options[option] = value
   end
@@ -103,9 +107,8 @@ function class:declareOptions ()
     return self._name
   end)
   self:declareOption("landscape", function(_, landscape)
-      if landscape then
-        self.landscape = SU.boolean(landscape, false)
-        SILE.documentState.landscape = self.landscape
+    if landscape then
+      self.landscape = landscape
     end
     return self.landscape
   end)

core/papersize.lua

@@ -64,18 +64,18 @@ local papersize = {
 
 setmetatable(papersize, {
     __call = function (self, size, landscape)
+      local geometry
       local _, _, x, y = string.find(size, "(.+)%s+x%s+(.+)")
       if x and y then
-        return { SILE.measurement(x):tonumber(), SILE.measurement(y):tonumber() }
+        geometry = { SILE.measurement(x):tonumber(), SILE.measurement(y):tonumber() }
       else
-        size = string.lower(size:gsub("[-%s]+", ""))
-        if self[size] then
-          if landscape then
-            self[size][1], self[size][2] = self[size][2], self[size][1]
-          end
-          return self[size]
-        end
+        local preset_name = string.lower(size:gsub("[-%s]+", ""))
+        geometry = self[preset_name]
       end
+      if SU.boolean(landscape) then
+        geometry[1], geometry[2] = geometry[2], geometry[1]
+      end
+      if geometry then return geometry end
       SU.error(string.format([[Unable to parse papersize '%s'.
   Custom sizes may be entered with 'papersize=<measurement> x <measurement>'.
   Predefined paper sizes include: %s]],