Re: PATCH: (provisional) underscores in constants in numeric evaluation

[Peter Stephenson <Peter.Stephenson@xxxxxxx>]

Here are some documentation and tests.

Index: Doc/Zsh/arith.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/arith.yo,v
retrieving revision 1.14
diff -p -u -r1.14 arith.yo
--- Doc/Zsh/arith.yo	19 Jun 2008 12:54:37 -0000	1.14
+++ Doc/Zsh/arith.yo	3 Sep 2012 11:34:20 -0000
@@ -48,6 +48,12 @@ The var(base)tt(#) may also be omitted, 
 base 10 is used.  For backwards compatibility the form
 `tt([)var(base)tt(])var(n)' is also accepted.
 
+An integer expression or a base given in the form
+`var(base)tt(#)var(n)', may contain underscores (`tt(_)') after the
+leading digit for visual guidance; these are ignored in computation.
+Examples are tt(1_000_000) or tt(0xffff_ffff) which are equivalent to
+tt(1000000) and tt(0xffffffff) respectively.
+
 It is also possible to specify a base to be used for output in the form
 `tt([#)var(base)tt(])', for example `tt([#16])'.  This is used when
 outputting arithmetical substitutions or when assigning to scalar
@@ -87,7 +93,9 @@ output is valid syntax for input.  If th
 Floating point constants are recognized by the presence of a decimal point
 or an exponent.  The decimal point may be the first character of the
 constant, but the exponent character tt(e) or tt(E) may not, as it will be
-taken for a parameter name.
+taken for a parameter name.  All numeric parts (before and after the
+decimal point and in the exponent) may contain underscores after the
+leading digit for visual guidance; these are ignored in computation.
 
 cindex(arithmetic operators)
 cindex(operators, arithmetic)
Index: Test/C01arith.ztst
===================================================================
RCS file: /cvsroot/zsh/zsh/Test/C01arith.ztst,v
retrieving revision 1.18
diff -p -u -r1.18 C01arith.ztst
--- Test/C01arith.ztst	20 Jan 2010 17:18:30 -0000	1.18
+++ Test/C01arith.ztst	3 Sep 2012 11:34:20 -0000
@@ -210,3 +210,26 @@
   print $x
 0:double increment for repeated expression
 >2
+
+  # Floating point.  Default precision should take care of rounding errors.
+  print $(( 1_0.000_000e0_1 ))
+  # Integer.
+  print $(( 0x_ff_ff_ ))
+  # _ are parts of variable names that don't start with a digit
+  __myvar__=42
+  print $(( __myvar__ + $__myvar__ ))
+  # _ is not part of variable name that does start with a digit
+  # (which are substituted before math eval)
+  set -- 6
+  print $(( $1_000_000 ))
+  # Underscores in expressions with no whitespace
+  print $(( 3_000_+4_000_/2 ))
+  # Underscores may appear in the base descriptor, for what it's worth...
+  print $(( 1_6_#f_f_ ))
+0:underscores in math constants
+>100.
+>65535
+>84
+>6000000
+>5000
+>255

-- 
Peter Stephenson <pws@xxxxxxx>            Software Engineer
Tel: +44 (0)1223 692070                   Cambridge Silicon Radio Limited
Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, UK


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