diff --git a/barrel/Utils/Table.cc b/barrel/Utils/Table.cc
index a4df863..c93f7b2 100644
--- a/barrel/Utils/Table.cc
+++ b/barrel/Utils/Table.cc
@@ -33,16 +33,38 @@ namespace barrel
     using namespace std;
 
 
+    struct Table::OutputInfo
+    {
+	OutputInfo(const Table& table);
+
+	void calculate_hidden(const Table& table, const Table::Row& row);
+	void calculate_widths(const Table& table, const Table::Row& row, unsigned indent);
+	size_t calculate_total_width(const Table& table) const;
+	void calculate_abbriviated_widths(const Table& table);
+
+	struct ColumnVars
+	{
+	    bool hidden = false;
+	    size_t width = 0;
+	};
+
+	vector<ColumnVars> column_vars;
+    };
+
+
     Table::OutputInfo::OutputInfo(const Table& table)
     {
-	// calculate hidden, default to false
+	if (table.column_params.size() != table.header.get_columns().size())
+	    throw runtime_error("column_params.size != header.size");
 
-	hidden.resize(table.header.get_columns().size());
+	column_vars.resize(table.header.get_columns().size());
 
-	for (size_t i = 0; i < table.visibilities.size(); ++i)
+	// calculate hidden, default to false
+
+	for (size_t idx = 0; idx < table.column_params.size(); ++idx)
 	{
-	    if (table.visibilities[i] == Visibility::AUTO || table.visibilities[i] == Visibility::OFF)
-		hidden[i] = true;
+	    if (table.column_params[idx].visibility == Visibility::AUTO || table.column_params[idx].visibility == Visibility::OFF)
+		column_vars[idx].hidden = true;
 	}
 
 	for (const Table::Row& row : table.rows)
@@ -50,7 +72,8 @@ namespace barrel
 
 	// calculate widths
 
-	widths = table.min_widths;
+	for (size_t idx = 0; idx < table.column_params.size(); ++idx)
+	    column_vars[idx].width = table.column_params[idx].min_width;
 
 	if (table.show_header)
 	    calculate_widths(table, table.header, 0);
@@ -67,10 +90,13 @@ namespace barrel
     {
 	const vector<string>& columns = row.get_columns();
 
-	for (size_t i = 0; i < min(columns.size(), table.visibilities.size()); ++i)
+	if (columns.size() > table.column_params.size())
+	    throw runtime_error("too many columns");
+
+	for (size_t idx = 0; idx < columns.size(); ++idx)
 	{
-	    if (table.visibilities[i] == Visibility::AUTO && !columns[i].empty())
-		hidden[i] = false;
+	    if (table.column_params[idx].visibility == Visibility::AUTO && !columns[idx].empty())
+		column_vars[idx].hidden = false;
 	}
 
 	for (const Table::Row& subrow : row.get_subrows())
@@ -83,20 +109,17 @@ namespace barrel
     {
 	const vector<string>& columns = row.get_columns();
 
-	if (columns.size() > widths.size())
-	    widths.resize(columns.size());
-
-	for (size_t i = 0; i < columns.size(); ++i)
+	for (size_t idx = 0; idx < columns.size(); ++idx)
 	{
-	    if (hidden[i])
+	    if (column_vars[idx].hidden)
 		continue;
 
-	    size_t width = mbs_width(columns[i]);
+	    size_t width = mbs_width(columns[idx]);
 
-	    if (i == table.tree_index)
+	    if (idx == table.tree_idx)
 		width += 2 * indent;
 
-	    widths[i] = max(widths[i], width);
+	    column_vars[idx].width = max(column_vars[idx].width, width);
 	}
 
 	for (const Table::Row& subrow : row.get_subrows())
@@ -114,9 +137,9 @@ namespace barrel
 
 	bool first = true;
 
-	for (size_t i = 0; i < widths.size(); ++i)
+	for (size_t idx = 0; idx < column_vars.size(); ++idx)
 	{
-	    if (hidden[i])
+	    if (column_vars[idx].hidden)
 		continue;
 
 	    if (first)
@@ -124,7 +147,7 @@ namespace barrel
 	    else
 		total_width += 2 + (table.show_grid ? 1 : 0);
 
-	    total_width += widths[i];
+	    total_width += column_vars[idx].width;
 	}
 
 	return total_width;
@@ -144,11 +167,11 @@ namespace barrel
 
 	size_t too_much = total_width - table.screen_width;
 
-	for (size_t i = 0; i < table.abbreviates.size(); ++i)
+	for (size_t idx = 0; idx < table.column_params.size(); ++idx)
 	{
-	    if (table.abbreviates[i])
+	    if (table.column_params[idx].abbreviate)
 	    {
-		widths[i] = max(widths[i] - too_much, (size_t) 5);
+		column_vars[idx].width = max(column_vars[idx].width - too_much, (size_t) 5);
 		break;
 	    }
 	}
@@ -156,23 +179,23 @@ namespace barrel
 
 
     void
-    Table::output(std::ostream& s, const Table::Row& row, const OutputInfo& output_info, const vector<bool>& lasts) const
+    Table::output(std::ostream& s, const OutputInfo& output_info, const Table::Row& row, const vector<bool>& lasts) const
     {
 	s << string(global_indent, ' ');
 
 	const vector<string>& columns = row.get_columns();
 
-	for (size_t i = 0; i < output_info.widths.size(); ++i)
+	for (size_t idx = 0; idx < output_info.column_vars.size(); ++idx)
 	{
-	    if (output_info.hidden[i])
+	    if (output_info.column_vars[idx].hidden)
 		continue;
 
-	    string column = i < columns.size() ? columns[i] : "";
+	    string column = idx < columns.size() ? columns[idx] : "";
 
-	    bool first = i == 0;
-	    bool last = i == output_info.widths.size() - 1;
+	    bool first = idx == 0;
+	    bool last = idx == output_info.column_vars.size() - 1;
 
-	    size_t extra = (i == tree_index) ? 2 * lasts.size() : 0;
+	    size_t extra = (idx == tree_idx) ? 2 * lasts.size() : 0;
 
 	    if (last && column.empty())
 		break;
@@ -180,7 +203,7 @@ namespace barrel
 	    if (!first)
 		s << " ";
 
-	    if (i == tree_index)
+	    if (idx == tree_idx)
 	    {
 		for (size_t tl = 0; tl < lasts.size(); ++tl)
 		{
@@ -193,10 +216,10 @@ namespace barrel
 
 	    size_t width = mbs_width(column);
 
-	    if (aligns[i] == Align::RIGHT)
+	    if (column_params[idx].align == Align::RIGHT)
 	    {
-		if (width < output_info.widths[i] - extra)
-		    s << string(output_info.widths[i] - width - extra, ' ');
+		if (width < output_info.column_vars[idx].width - extra)
+		    s << string(output_info.column_vars[idx].width - width - extra, ' ');
 	    }
 
 	    s << column;
@@ -204,10 +227,10 @@ namespace barrel
 	    if (last)
 		break;
 
-	    if (aligns[i] == Align::LEFT)
+	    if (column_params[idx].align == Align::LEFT)
 	    {
-		if (width < output_info.widths[i] - extra)
-		    s << string(output_info.widths[i] - width - extra, ' ');
+		if (width < output_info.column_vars[idx].width - extra)
+		    s << string(output_info.column_vars[idx].width - width - extra, ' ');
 	    }
 
 	    s << " ";
@@ -223,7 +246,7 @@ namespace barrel
 	{
 	    vector<bool> sub_lasts = lasts;
 	    sub_lasts.push_back(i == subrows.size() - 1);
-	    output(s, subrows[i], output_info, sub_lasts);
+	    output(s, output_info, subrows[i], sub_lasts);
 	}
     }
 
@@ -236,15 +259,15 @@ namespace barrel
     {
 	s << string(global_indent, ' ');
 
-	for (size_t i = 0; i < output_info.widths.size(); ++i)
+	for (size_t idx = 0; idx < output_info.column_vars.size(); ++idx)
 	{
-	    if (output_info.hidden[i])
+	    if (output_info.column_vars[idx].hidden)
 		continue;
 
-	    for (size_t j = 0; j < output_info.widths[i]; ++j)
+	    for (size_t j = 0; j < output_info.column_vars[idx].width; ++j)
 		s << glyph(1);
 
-	    if (i == output_info.widths.size() - 1)
+	    if (idx == output_info.column_vars.size() - 1)
 		break;
 
 	    s << glyph(1) << glyph(2) << glyph(1);
@@ -254,12 +277,23 @@ namespace barrel
     }
 
 
+    bool
+    Table::has_id(Id id) const
+    {
+	for (size_t idx = 0; idx < column_params.size(); ++idx)
+	    if (column_params[idx].id == id)
+		return true;
+
+	return false;
+    }
+
+
     size_t
-    Table::id_to_index(Id id) const
+    Table::id_to_idx(Id id) const
     {
-	for (size_t i = 0; i < ids.size(); ++i)
-	    if (ids[i] == id)
-		return i;
+	for (size_t idx = 0; idx < column_params.size(); ++idx)
+	    if (column_params[idx].id == id)
+		return idx;
 
 	throw runtime_error("id not found");
     }
@@ -268,12 +302,12 @@ namespace barrel
     string&
     Table::Row::operator[](Id id)
     {
-	size_t i = table.id_to_index(id);
+	size_t idx = table.id_to_idx(id);
 
-	if (columns.size() < i + 1)
-	    columns.resize(i + 1);
+	if (columns.size() < idx + 1)
+	    columns.resize(idx + 1);
 
-	return columns[i];
+	return columns[idx];
     }
 
 
@@ -296,8 +330,7 @@ namespace barrel
 	for (const Cell& cell : init)
 	{
 	    header.add(cell.name);
-	    ids.push_back(cell.id);
-	    aligns.push_back(cell.align);
+	    column_params.emplace_back(cell.id, cell.align);
 	}
     }
 
@@ -308,8 +341,7 @@ namespace barrel
 	for (const Cell& cell : init)
 	{
 	    header.add(cell.name);
-	    ids.push_back(cell.id);
-	    aligns.push_back(cell.align);
+	    column_params.emplace_back(cell.id, cell.align);
 	}
     }
 
@@ -317,43 +349,31 @@ namespace barrel
     void
     Table::set_min_width(Id id, size_t min_width)
     {
-	size_t i = id_to_index(id);
-
-	if (min_widths.size() < i + 1)
-	    min_widths.resize(i + 1);
-
-	min_widths[i] = min_width;
+	size_t idx = id_to_idx(id);
+	column_params[idx].min_width = min_width;
     }
 
 
     void
     Table::set_visibility(Id id, Visibility visibility)
     {
-	size_t i = id_to_index(id);
-
-	if (visibilities.size() < i + 1)
-	    visibilities.resize(i + 1);
-
-	visibilities[i] = visibility;
+	size_t idx = id_to_idx(id);
+	column_params[idx].visibility = visibility;
     }
 
 
     void
     Table::set_abbreviate(Id id, bool abbreviate)
     {
-	size_t i = id_to_index(id);
-
-	if (abbreviates.size() < i + 1)
-	    abbreviates.resize(i + 1);
-
-	abbreviates[i] = abbreviate;
+	size_t idx = id_to_idx(id);
+	column_params[idx].abbreviate = abbreviate;
     }
 
 
     void
     Table::set_tree_id(Id id)
     {
-	tree_index = id_to_index(id);
+	tree_idx = id_to_idx(id);
     }
 
 
@@ -367,13 +387,13 @@ namespace barrel
 	// output header and rows
 
 	if (table.show_header)
-	    table.output(s, table.header, output_info, {});
+	    table.output(s, output_info, table.header, {});
 
 	if (table.show_header && table.show_grid)
 	    table.output(s, output_info);
 
 	for (const Table::Row& row : table.rows)
-	    table.output(s, row, output_info, {});
+	    table.output(s, output_info, row, {});
 
 	return s;
     }
diff --git a/barrel/Utils/Table.h b/barrel/Utils/Table.h
index 67ec5b5..356ff2b 100644
--- a/barrel/Utils/Table.h
+++ b/barrel/Utils/Table.h
@@ -142,6 +142,8 @@ namespace barrel
 
 	const vector<Row> get_rows() const { return rows; }
 
+	bool has_id(Id id) const;
+
 	void set_show_header(bool show_header) { Table::show_header = show_header; }
 	void set_show_grid(bool show_grid) { Table::show_grid = show_grid; }
 	void set_style(Style style) { Table::style = style; }
@@ -166,30 +168,26 @@ namespace barrel
 	Style style = Style::ASCII;
 	size_t global_indent = 0;
 	size_t screen_width = -1;
+	size_t tree_idx = 0;
 
-	vector<Align> aligns;
-	vector<Id> ids;
-	vector<size_t> min_widths;
-	vector<Visibility> visibilities;
-	vector<bool> abbreviates;
-	size_t tree_index = 0;
+	struct ColumnParams
+	{
+	    ColumnParams(Id id, Align align) : id(id), align(align) {}
 
-	size_t id_to_index(Id id) const;
+	    Id id = Id::NONE;
+	    Align align = Align::LEFT;
+	    size_t min_width = 0;
+	    Visibility visibility = Visibility::ON;
+	    bool abbreviate = false;
+	};
 
-	struct OutputInfo
-	{
-	    OutputInfo(const Table& table);
+	vector<ColumnParams> column_params;
 
-	    void calculate_hidden(const Table& table, const Table::Row& row);
-	    void calculate_widths(const Table& table, const Table::Row& row, unsigned indent);
-	    size_t calculate_total_width(const Table& table) const;
-	    void calculate_abbriviated_widths(const Table& table);
+	size_t id_to_idx(Id id) const;
 
-	    vector<bool> hidden;
-	    vector<size_t> widths;
-	};
+	struct OutputInfo;
 
-	void output(std::ostream& s, const Table::Row& row, const OutputInfo& output_info,
+	void output(std::ostream& s, const OutputInfo& output_info, const Table::Row& row,
 		    const vector<bool>& lasts) const;
 
 	void output(std::ostream& s, const OutputInfo& output_info) const;
diff --git a/testsuite/table.cc b/testsuite/table.cc
index 399e4d6..20ce689 100644
--- a/testsuite/table.cc
+++ b/testsuite/table.cc
@@ -10,6 +10,44 @@ using namespace barrel;
 
 
 BOOST_AUTO_TEST_CASE(test1)
+{
+    Table table({ "A", "B" });
+
+    table.set_style(Style::LIGHT);
+
+    Table::Row row1(table, { "a" });
+    table.add(row1);
+
+    Table::Row row2(table, { "a", "b" });
+    table.add(row2);
+
+    ostringstream o;
+    o << table;
+
+    string s =
+	"A │ B\n"
+	"──┼──\n"
+	"a │\n"
+	"a │ b\n";
+
+    BOOST_CHECK_EQUAL(o.str(), s);
+}
+
+
+BOOST_AUTO_TEST_CASE(test2)
+{
+    Table table({ "A", "B" });
+
+    Table::Row row1(table, { "a", "b", "c" });
+    table.add(row1);
+
+    BOOST_CHECK_EXCEPTION({ ostringstream tmp; tmp << table; }, runtime_error, [](const exception& e) {
+        return strcmp(e.what(), "too many columns") == 0;
+    });
+}
+
+
+BOOST_AUTO_TEST_CASE(test3)
 {
     Table table({ "Name", Cell("Size", Id::SIZE, Align::RIGHT), "Usage" });
     table.set_style(Style::LIGHT);
@@ -38,7 +76,7 @@ BOOST_AUTO_TEST_CASE(test1)
 }
 
 
-BOOST_AUTO_TEST_CASE(test2)
+BOOST_AUTO_TEST_CASE(test4)
 {
     Table table({ "Name", Cell("Size", Id::SIZE, Align::RIGHT) });
     table.set_style(Style::LIGHT);
@@ -85,7 +123,7 @@ BOOST_AUTO_TEST_CASE(test2)
 }
 
 
-BOOST_AUTO_TEST_CASE(test3)
+BOOST_AUTO_TEST_CASE(test5)
 {
     Table table({ "Name", "Level" });
     table.set_style(Style::LIGHT);
@@ -127,7 +165,7 @@ BOOST_AUTO_TEST_CASE(test3)
 }
 
 
-BOOST_AUTO_TEST_CASE(test4)
+BOOST_AUTO_TEST_CASE(test6)
 {
     Table table({ "Level", Cell("Name", Id::NAME) });
     table.set_style(Style::LIGHT);
@@ -151,7 +189,7 @@ BOOST_AUTO_TEST_CASE(test4)
 }
 
 
-BOOST_AUTO_TEST_CASE(test5)
+BOOST_AUTO_TEST_CASE(test7)
 {
     Table table({ "Level", Cell("Name", Id::NAME) });
     table.set_style(Style::ASCII);