Added unique error messages when indexing into a sequence.

errors.lua

@@ -96,6 +96,34 @@ local function correct_error (self, module_suffix, format_msg, gotten_string, po
     return error(('[%s%s]: '..format_msg):format(self.module_name, module_suffix, gotten_string, list_string), 3)
 end
 
+----
+
+local function handle_index_error (err_hdl, t, key)
+    --
+    assert(type(err_hdl) == 'table')
+    assert(type(t)       == 'table')
+    -- Find keys
+    local keys = {}
+    for k in pairs(t) do  keys[#keys+1] = k  end
+    -- Is empty table?
+    if #keys == 0 then
+        external_error(err_hdl, '', 'Attempting to index unknown key %s in an empty table.', key)
+    end
+    -- Is sequence?
+    if #keys == #t then
+        if type(key) ~= 'number' then
+            external_error(err_hdl, '', 'Attempting to index %s key %s, for sequence with length %i.', type(key), key, #t)
+        elseif key == math.floor(key) then -- Integer
+            external_error(err_hdl, '', 'Attempting to index position %i, for sequence with length %i.', key, #t)
+        end
+    end
+    -- Is map?
+    for i = 1, #keys do  keys[i] = tostring(keys[i])  end
+    correct_error(err_hdl, '', 'Attempting to index unknown key %s, maybe you meant %s?', tostring(key), keys)
+end
+
+----
+
 
 local ErrorHandler_mt = {__call = function (self, ...) internal_error(self, '', ...)  end}
 
@@ -144,13 +172,12 @@ return function (module_name)
         if args[1] == err_hdl then  table.remove(args, 1)  end
         return setmetatable(args[1] or {}, {
             __index = function (t, k)
-                local keys = {}
+                return handle_index_error(err_hdl, t, k)
-                for k in pairs(t) do  keys[#keys+1] = tostring(k)  end
-                if #keys == 0 then  external_error(err_hdl, '', 'Attempting to index unknown key %s in an empty table.', k)  end
-                correct_error(err_hdl, '', 'Attempting to index unknown key %s, maybe you meant %s?', k, keys)
             end
         })
     end
 
+    err_hdl.register(format_probable_strings, internal_error, external_error, correct_error, handle_index_error, err_hdl.internal, err_hdl.external, err_hdl.correct, err_hdl.register, err_hdl.strict_table)
+
     return err_hdl
 end

test/test_errors.lua

@@ -111,13 +111,13 @@ end)
 
 SUITE:addTest('Strict tables throw errors on unknown indices', function()
 	local t   =  error.strict_table { a = 1, b = 2, c = 3 }
-	print(bad_call(function() return t.hello end))
+	bad_call(function() return t.hello end)
 end)
 
 SUITE:addTest('Strict tables throw errors on unknown indices, even if table contains number keys', function()
-	local t   =  error.strict_table { 'hi', 'hello', 'world' }
+	local t   =  error.strict_table { 'hi', 'hello', 'world', aa = 1, ab = 2, ac = 3 }
-	local msg = bad_call(function() return t.hello end)
+	local msg = bad_call(function() return t.a end)
-	assert_equal('[test_errors]: Attempting to index unknown key hello, maybe you meant 1, 2 or 3?', msg)
+	assert_equal('[test_errors]: Attempting to index unknown key a, maybe you meant ac, aa or ab?', msg)
 end)
 
 SUITE:addTest('Strict tables throw specific error on empty table', function()
@@ -125,6 +125,24 @@ SUITE:addTest('Strict tables throw specific error on empty table', function()
 	bad_call(function() return t.hello end)
 end)
 
+SUITE:addTest('Strict tables throws errors on indexing strings in sequence', function()
+	local t   =  error.strict_table { 'turing', 'church', 'ada', 'hopper' }
+	local msg = bad_call(function() return t.hello end)
+	assert_equal('./test/test_errors.lua:'..curline(-1)..': [test_errors]: Attempting to index string key hello, for sequence with length 4.', msg)
+end)
+
+SUITE:addTest('Strict tables throws errors on sequence under-access', function()
+	local t   =  error.strict_table { 'turing', 'church', 'ada', 'hopper' }
+	local msg = bad_call(function() return t[0] end)
+	assert_equal('./test/test_errors.lua:'..curline(-1)..': [test_errors]: Attempting to index position 0, for sequence with length 4.', msg)
+end)
+
+SUITE:addTest('Strict tables throws errors on sequence over-access', function()
+	local t   =  error.strict_table { 'turing', 'church', 'ada', 'hopper' }
+	local msg = bad_call(function() return t[7] end)
+	assert_equal('./test/test_errors.lua:'..curline(-1)..': [test_errors]: Attempting to index position 7, for sequence with length 4.', msg)
+end)
+
 
 
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