audit all asserts

Each one should provide a message that will show up within LÖVE. Stop
relying on nearby prints to the terminal.

I also found some unnecessary ones.

There is some potential here for performance regressions: the format()
calls will trigger whether or not the assertion fails, and cause
allocations. So far Lua's GC seems good enough to manage the load even
with Moby Dick, even in some situations that caused issues in the past
like undo.

1 files changed, 7 insertions, 8 deletions

diff --git a/source_undo.lua b/source_undo.lua
index d3d5f0f..e5dea93 100644
--- a/source_undo.lua
+++ b/source_undo.lua
@@ -36,11 +36,11 @@ end
 -- Make copies of objects; the rest of the app may mutate them in place, but undo requires immutable histories.
 function snapshot(State, s,e)
   -- Snapshot everything by default, but subset if requested.
-  assert(s)
+  assert(s, 'failed to snapshot operation for undo history')
   if e == nil then
     e = s
   end
-  assert(#State.lines > 0)
+  assert(#State.lines > 0, 'failed to snapshot operation for undo history')
   if s < 1 then s = 1 end
   if s > #State.lines then s = #State.lines end
   if e < 1 then e = 1 end
@@ -65,8 +65,7 @@ function snapshot(State, s,e)
     elseif line.mode == 'drawing' then
       table.insert(event.lines, {mode='drawing', h=line.h, points=deepcopy(line.points), shapes=deepcopy(line.shapes), pending={}})
     else
-      print(line.mode)
-      assert(false)
+      assert(false, ('unknown line mode %s'):format(line.mode))
     end
   end
   return event
@@ -80,22 +79,22 @@ function patch(lines, from, to)
 --?     lines[from.start_line] = to.lines[1]
 --?     return
 --?   end
-  assert(from.start_line == to.start_line)
+  assert(from.start_line == to.start_line, 'failed to patch undo operation')
   for i=from.end_line,from.start_line,-1 do
     table.remove(lines, i)
   end
-  assert(#to.lines == to.end_line-to.start_line+1)
+  assert(#to.lines == to.end_line-to.start_line+1, 'failed to patch undo operation')
   for i=1,#to.lines do
     table.insert(lines, to.start_line+i-1, to.lines[i])
   end
 end
 
 function patch_placeholders(line_cache, from, to)
-  assert(from.start_line == to.start_line)
+  assert(from.start_line == to.start_line, 'failed to patch undo operation')
   for i=from.end_line,from.start_line,-1 do
     table.remove(line_cache, i)
   end
-  assert(#to.lines == to.end_line-to.start_line+1)
+  assert(#to.lines == to.end_line-to.start_line+1, 'failed to patch undo operation')
   for i=1,#to.lines do
     table.insert(line_cache, to.start_line+i-1, {})
   end