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PerlMonks calc - A Perl Shell

by ruoso (Curate)
on May 31, 2006 at 18:05 UTC ( #552887=CUFP: print w/replies, xml ) Need Help??

Using a trick by fglock, and with the help of the guys at (at, here is the calc, which I now use in place of bc...

Obviously, you'll see it's just a Perl Shell that have some calculator shortcuts, so, you can do whatever you want with it...

#!/usr/bin/perl use strict; use warnings; use Term::ReadLine; my $name = ' calc'; print $name.$/; my $term = Term::ReadLine->new($name); $term->Features()->{'autohistory'} = 1; my $prompt = "> "; my $OUT = $term->OUT || \*STDOUT; my $___eval_str___; my $M = 0; my $scale = 2; sub ler { my $a = $term->readline($prompt); unless (defined $a) { print $/; exit(0); } return $a; } sub substituir { my $a = shift; $a =~ s/^(.+)(\*\*)$/\$M $2 $1/; $a =~ s/^(.+)(\+|\-|\*|\/)$/\$M $2 $1/; $a =~ s/\;\s*$//; if ($a =~ /^\s*do {\s*$/) { my $block = ''; my $count = 1; while (defined($_=$term->readline(' '.('.'x$count).' ' +))) { while ($_ =~ m/\{/g) { $count++; } while ($_ =~ m/\}/g) { $count--; } last if $count < 1; $block .= $_; } $a = 'do {'.$block.'}'; } return $a; } sub falar { my $a = shift; if ($@) { print "! ".$@; } else { if (defined $a && $a =~ /^[\d\.]$/) { $M=sprintf("%.".$scale."f",$a); } elsif ($a) { $M=$a; } print $OUT "= ".$M.$/ if defined $M; } } sub doit { $___eval_str___ = ' eval(" falar(".substituir(ler())."); $___eval_str___; "); if($@){ print "! ".$@; eval($___eval_str___) } '; eval $___eval_str___; } doit();

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Re: calc - A Perl Shell
by AltBlue (Chaplain) on Jun 01, 2006 at 07:56 UTC
    Perl, computing... hmm ;-) Compare these:
    $ echo 'x=y=1.2; x+=1.1; x-=1.1; x; y; x==y' |bc |xargs echo 1.2 1.2 1
    $ perl -wle '$x=$y=1.2; $x+=1.1; $x-=1.1; $,=$"; print $x, $y, $x == $ +y' 1.2 1.2
    don't you love perl? ;-)

      As a quick calculator (especially with vector/matrix ops) I like the J programming language. It's not quite good as a real programming language IMO, but it's ideal for doing some quick numeric computations. GNU octave is good for the same purpose as well.

Re: calc - A Perl Shell
by Scott7477 (Chaplain) on May 31, 2006 at 19:42 UTC
    I ran this on Windows XP SP2 using ActiveState 5.8.7 and got this error message:
    SetConsoleMode failed, LastError=|6| at c:/Perl/site/lib/Term/ line 265.

      try without the $term->Features() line... If that still doesn't work, file a bug report against Term::ReadLine, or Term::ReadKey, or ActiveState...

      BTW... you still can try changing the $term->readline() for <STDIN>, i think.

Re: calc - A Perl Shell
by Discipulus (Monsignor) on Jun 01, 2006 at 07:28 UTC
    run fine on w2k SP4 perl, v5.8.6 built for MSWin32-x86-multi-thread ActiveState. ty

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[ambrus]: (b) a good presentation system that lets the presenter quickly interactively edit the slides live during a presentation, to combine the advantages of blackboard and overhead slide styles in modern tech
[Corion]: Heh - in university, I cheated on (a) by doing blackboard presentations using chalk. But those were 2 hour presentations, not quick/essential/ reduced presentations where you want to show something quick
[ambrus]: (either on just one screen or two screens). this is necessary because
[ambrus]: overhead slide plus blackboard is inconvenient because the lighting conditions are different and they require separate areas you can't quickly repartition, and typing on keyboard is faster and more convenient than writing on a blackboard
[Corion]: (b) would be cool. I've thought about this doing Pod editing, and even simply regenerating/live updating the browser makes things much more interactive
[ambrus]: modern computers have way enough processing power to allow this, at least for geeks who are willing to spend a few weeks to learn a tricky new user interface like vim
[Corion]: ambrus: Well, for mathematical notation, I find blackboard much more convenient than a computer. But when inserting text or moving text around, the computer wins obviously
[ambrus]: But either of these is a big problem in practice, so I'd need to spend like thirty years of my life to solve (a) and five more years to solve (b)
[ambrus]: Corion: yes, CURRENTLY the blackboard is more convenient
[ambrus]: and it's not like I want to ban blackboards anyway

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