Author: wyoung
Date: Fri Dec 28 09:33:06 2007
New Revision: 2030
URL: http://svn.gna.org/viewcvs/mysqlpp?rev=2030&view=rev
Log:
sql_cmp(float, float) and sql_cmp(double, double), which make up part of
the implementation of less-than comparison for SSQLS no longer do exact
equality tests. They now offer a user-settable threshold, which if the
absolute value of the difference between the values is under this
threshold, causes the test to return "equal".
Modified:
trunk/ChangeLog
trunk/Wishlist
trunk/lib/custom.pl
Modified: trunk/ChangeLog
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/ChangeLog?rev=2030&r1=2029&r2=2030&view=diff
==============================================================================
--- trunk/ChangeLog (original)
+++ trunk/ChangeLog Fri Dec 28 09:33:06 2007
@@ -39,6 +39,17 @@
undocumented and unexemplified for a very long time now.
- You can now use 'bool' type in SSQLS.
+
+ - SSQLSes have always had a < operator defined for them for
+ various reasons, which compares the first N fields, where N
+ is the second parameter to sql_create_X. Earlier versions
+ of MySQL++ did comparisons using exact equality for all data
+ types including floating-point. Now there is a configurable
+ value at the top of lib/custom.pl that lets you set the
+ minimum threshold between two floating point values such
+ that they will be considered equal. It's also possible to
+ redefine this threshold on a per-module basis by #defining
+ MYSQLPP_FP_MIN_DELTA before #including custom.h.
o You can now use mysqlpp::null as a template query parameter to
get a SQL null.
Modified: trunk/Wishlist
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/Wishlist?rev=2030&r1=2029&r2=2030&view=diff
==============================================================================
--- trunk/Wishlist (original)
+++ trunk/Wishlist Fri Dec 28 09:33:06 2007
@@ -82,11 +82,6 @@
http://dev.mysql.com/doc/refman/5.0/en/identifiers.html
- o Define custom template for sql_double et al., with the comparison
- precision being the parameter:
-
- http://lists.mysql.com/plusplus/3984
-
o Define operator<< for Fields, Row, StoreQueryResult, etc. In other
words, there should be a way to get a user-readable version of
received data without a lot of code. CSV format by default, and
Modified: trunk/lib/custom.pl
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/lib/custom.pl?rev=2030&r1=2029&r2=2030&view=diff
==============================================================================
--- trunk/lib/custom.pl (original)
+++ trunk/lib/custom.pl Fri Dec 28 09:33:06 2007
@@ -35,6 +35,14 @@
# only if you must.
my $max_data_members = 25;
+# To make comparisons between floating point values, we subtract them,
+# take the absolute value, and test to see if that delta is under this
+# value. If it is, we call the two values "equal". Change this as fits
+# your need for precision. Note that we express it as a string because
+# we want the value copied literally into custom.h, not "preprocessed"
+# by Perl as a floating-point value.
+my $fp_min_delta = "0.00001";
+
# No user-serviceable parts below.
@@ -61,6 +69,18 @@
#include "sql_types.h"
#include <string>
+
+#include <math.h>
+
+// Smallest difference between two floating point numbers recognized
+// in making comparisons. If the absolute delta is under this
+// threshold, the two values are considered equal. You can either
+// override this permanently by changing custom.pl, or you can do it
+// on a case-by-case basis at compile time by defining this to another
+// value before #including this header.
+#if !defined(MYSQLPP_FP_MIN_DELTA)
+# define MYSQLPP_FP_MIN_DELTA $fp_min_delta
+#endif
namespace mysqlpp {
@@ -113,13 +133,26 @@
---
}
[EMAIL PROTECTED] = ("double", "float", "longlong", "ulonglong");
[EMAIL PROTECTED] = ("longlong", "ulonglong");
foreach my $type (@types) {
print OUT0 << "---";
inline int sql_cmp($type a, $type b)
{
if (a == b) return 0;
+ if (a < b) return -1;
+ return 1;
+}
+---
+}
+
[EMAIL PROTECTED] = ("double", "float");
+foreach my $type (@types) {
+ print OUT0 << "---";
+
+inline int sql_cmp($type a, $type b)
+{
+ if (fabs(a - b) < MYSQLPP_FP_MIN_DELTA) return 0;
if (a < b) return -1;
return 1;
}
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