a calculator for zsh - zcalc and pcal conflict

[kwong@xxxxxxxxxxxxxxxxxxxx]

All,

Earlier I posted a calculator "pcal" written in perl as
a followup to Clifford's post of "zcalc" written in zsh.

Andy Spiegl noticed a problem and his email is attached
below.

After some discussion, we figured out that this is due to
a conflict between the way "zcalc" and "pcal" uses the
variable "ans".

When "zcalc" is called, it implicitly typeset the variable
"ans" to -E (float). Once that is done, it is irreversible
until you "unset ans".  And if you then use "pcal", it will
bomb if "ans" is set to a non-numerical value.

Some ways to work around it (none is ideal):

   * refrain from using "zcalc" and then "pcal".
   
   * "ans" for "zcalc" and "an" for "pcal" (you have to
     modify the definition of pcal.s2 to change all "ans" to
     "an".

mk

********************************************************************

Andy wrote:

> 
> Hi Kwong,
> 
> great stuff too!
> 
> > Let me know if you find any bugs.
> I'm not sure if it's a bug, but it's strange and I don't understand why.
> It seems to have to do with the calculator of Clifford, because this
> happens:
> 
>  condor:~>pcal h abc * d
>  ans = 8b8c
> 
>  condor:~>zcalc '4 * 4'
>  zcalc: bad math expression: operator expected at `b8c'
>  zsh: exit 1
> 
>  condor:~>unset ans
> 
>  condor:~>zcalc '4 * 4'
>  16
> 
>  condor:~>pcal h abc * d
>  pcal-ans:4: bad math expression: operator expected at `b8c'
>  zsh: exit 1
> 
> Can you see why the two interfere???  $ans only holds a number, right?
> Besides I'm not even using ans in this example.  Strange.
> 
> So I turned on debugging (see below) and get this:
>  condor:~>print $ans
>  3
> 
>  condor:~>pcal h abc * d
>  trace pcal-ans:2(if)> [[ -n h abc * d ]]
>  trace pcal-ans:4(then)> _x=trace pcal-ans:4(then cmdsubst)> echo h abc * d
>  trace pcal-ans:4(then)> _x=trace pcal-ans:4(then cmdsubst pipe)> sed s/ans/3/g
>  trace pcal-ans:4(then)> _x=h abc * d 
>  trace pcal-ans:5(then)> ans=trace pcal-ans:5(then cmdsubst)> pcal.pl h abc * d
>  trace pcal-ans:5(then)> ans=8b8c pcal-ans:5: bad math expression: operator expected at `b8c'
> 
> I don't get it, sorry.
> 
> Okay, I've saved your script as pcal.pl and put this into my .zsh/alias:
> 
>  pcal-ans() {
>  set -x
>    if [[ -n "$*" ]]
>    then
>      _x=`echo $* | sed "s/ans/$ans/g"`
>      ans=`noglob pcal.pl $_x` 
>      print ans = $ans
>      unset _x
>    else
>       pcal.pl
>    fi
>  set +x
>  }   
>  alias pcal='noglob pcal-ans'
> 
>  # ----------------------------------------------------------------------
>  # Here are some quick calculators that output in integer
>  # hexadecimal, decimal, and binary.
>  zcalc ()  { print $(( ans = ${@:-ans} )) }
>  zcalch () { print $(( [#16] ans = ${@:-ans} )) }   
>  zcalcd () { print $(( [#10] ans = ${@:-ans} )) }
>  zcalco () { print $(( [#8] ans = ${@:-ans} )) }
>  zcalcb () { print $(( [#2] ans = ${@:-ans} )) }
> 
>  # A key binding that will allow you to quickly get into zcalc
>  bindkey -s '\C-xd' "zcalc "
> 
>  # this last one lets you calculate the ascii value of a single character
>  zcalcasc () { print $(( [#16] ans = ##${@:-ans} )) }
>  # -------------------------------------------------------------------end
> 
> 
> Any help would be very much appreciated!
> Thanks,
>  Andy.
> 
> -- 
>            http://peru.spiegl.de  Our project
>       http://radiomaranon.org.pe  Radio Marañón, Jaén, Perú
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