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authorPeter Stephenson <pws@zsh.org>2015-01-15 15:07:26 +0000
committerPeter Stephenson <pws@zsh.org>2015-01-15 15:07:26 +0000
commit2b8b1a49d5c16aebe4276370d973ec79304df6a7 (patch)
tree8f19209fb929b52e689400942c06e922f2e8de6d /README
parent3a99ef322dafcd2cf833b2a0668436ac120df1b3 (diff)
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34290: note FORCE_FLOAT option change
Diffstat (limited to 'README')
-rw-r--r--README49
1 files changed, 45 insertions, 4 deletions
diff --git a/README b/README
index 4d2b6c17e..94df2a561 100644
--- a/README
+++ b/README
@@ -38,10 +38,12 @@ details, see the documentation.
Incompatibilites between 5.0.7 and 5.0.8
----------------------------------------
-A couple of arithmetic operations have changed: the new behaviour
-is intended to be more consistent, but is not compatible with the old.
+Various arithmetic operations have changed, in particular with respect
+to the choice of integer or floating point operations. The new
+behaviour is intended to be more consistent, but is not compatible with
+the old.
-Previously, the modulus operation, `%', implicitly converted the
+1) Previously, the modulus operation, `%', implicitly converted the
operation to integer and output an integer result, even if one
or both of the arguments were floating point. Now, the C math
library fmod() operator is used to implement the operation where
@@ -57,7 +59,8 @@ New behaviour:
% print $(( 5.5 % 2 ))
1.5
-Previously, assignments to variables assigned the correct type to
+
+2) Previously, assignments to variables assigned the correct type to
variables declared as floating point or integer, but this type was
not propagated to the value of the expression, as a C programmer
would naturally expect. Now, the type of the variable is propagated
@@ -81,6 +84,44 @@ New behaviour:
% print $var
2
+
+3) Previously, the FORCE_FLOAT option only forced the use of floating
+point in arithmetic expressions for integer constants, i.e. numbers
+typed directly into the expression, but not for variables. Hence
+an operation involving only integer variables (or string variables
+containing integers) was not forced to be performed with floating point
+arithmetic. Now, operations involving variables are also forced to
+floating point. For example:
+
+Old behaviour:
+
+% unsetopt FORCE_FLOAT
+% print $(( 1 / 2 ))
+0
+% integer i=1 j=2
+% print $(( i / j ))
+0
+% setopt FORCE_FLOAT
+% print $(( 1 / 2 ))
+0.5
+% print $(( i / j ))
+0
+
+New behaviour:
+
+% unsetopt FORCE_FLOAT
+% print $(( 1 / 2 ))
+0
+% integer i=1 j=2
+% print $(( i / j ))
+0
+% setopt FORCE_FLOAT
+% print $(( 1 / 2 ))
+0.5
+% print $(( i / j ))
+0.5
+
+
Incompatibilities between 5.0.2 and 5.0.5
-----------------------------------------