[lmi-commits] [lmi] master ad23b9e 2/2: Rework the commit just reverted

[Greg Chicares]

branch: master
commit ad23b9eef1f4421ec4453a69ccedd92a9cb3b056
Author: Gregory W. Chicares <address@hidden>
Commit: Gregory W. Chicares <address@hidden>

    Rework the commit just reverted
    
    See the four immediately preceding commits.
    
    Upon reflection, this part of the penultimate commit message:
    |     ,rows_per_group_ {0 < rows_per_group ? rows_per_group : throw 0;}
    |   which is less readable than this commit.
    seems incorrect: "less" should have been "more". Accordingly, used that
    technique in this commit, on the only argument for which a value of
    zero could cause a division-by-zero fault. See:
      https://lists.nongnu.org/archive/html/lmi/2018-09/msg00001.html
    
    Now that the ctor arguments are less obviously equivalent to their
    corresponding data members, restated the precondition assertions in
    terms of the arguments themselves.
---
 report_table.cpp      | 15 +++++++++++----
 report_table_test.cpp |  6 ++----
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/report_table.cpp b/report_table.cpp
index 5a55979..1eaf9c4 100644
--- a/report_table.cpp
+++ b/report_table.cpp
@@ -31,6 +31,7 @@
 #include <algorithm>                    // min()
 #include <numeric>                      // accumulate()
 #include <queue>
+#include <stdexcept>
 #include <utility>                      // pair
 
 /// Apportion "seats" to "states" by their respective total "votes".
@@ -175,11 +176,17 @@ std::vector<int> set_column_widths
     return w;
 }
 
+namespace
+{
+// An assertion to this effect is emulated in the ctor-initializer.
+std::runtime_error yikes("Rows per group must be positive.");
+} // Unnamed namespace.
+
 /// Preconditions: 0 <= total_rows && 0 < rows_per_group <= max_lines_per_page
 
 paginator::paginator(int total_rows, int rows_per_group, int 
max_lines_per_page)
     :total_rows_         {total_rows}
-    ,rows_per_group_     {rows_per_group}
+    ,rows_per_group_     {0 < rows_per_group ? rows_per_group : throw yikes}
     ,max_lines_per_page_ {max_lines_per_page}
     // "+ 1": blank-line separator after each group.
     ,lines_per_group_    {rows_per_group_ + 1}
@@ -188,9 +195,9 @@ paginator::paginator(int total_rows, int rows_per_group, 
int max_lines_per_page)
     ,rows_per_page_      {rows_per_group_ * groups_per_page_}
     ,page_count_         {1}
 {
-    LMI_ASSERT(0 <= total_rows_);
-    LMI_ASSERT(0 <  rows_per_group_                       );
-    LMI_ASSERT(     rows_per_group_ <= max_lines_per_page_);
+    LMI_ASSERT(0 <= total_rows);
+    LMI_ASSERT(0 <  rows_per_group                      );
+    LMI_ASSERT(     rows_per_group <= max_lines_per_page);
 
     // If there are zero rows of data, then one empty page is wanted.
     if(0 == total_rows_)
diff --git a/report_table_test.cpp b/report_table_test.cpp
index 68f7e7e..d07ce70 100644
--- a/report_table_test.cpp
+++ b/report_table_test.cpp
@@ -436,17 +436,15 @@ void report_table_test::test_paginator()
     BOOST_TEST_THROW
         (paginator(1, 0, 1)
         ,std::runtime_error
-        ,lmi_test::what_regex("^Assertion.*failed")
+        ,"Rows per group must be positive."
         );
 
     // Negative number of rows per group.
-#if 0
     BOOST_TEST_THROW
         (paginator(1, -1, 1)
         ,std::runtime_error
-        ,lmi_test::what_regex("^Assertion.*failed")
+        ,"Rows per group must be positive."
         );
-#endif // 0
 
     // Insufficient room to print even one group.
     BOOST_TEST_THROW