Re^9: converting binary to decimal

[tybalt89]

Er, Umm, no.

$ perl -le 'print(0 . $_ | 1 . 1) for qw/0 2 4 6 8/'
11
13
15
17
19

Most probable reason you are seeing what you saw -> you did "use feature 'bitwise'" earlier in your debugging session. 'bitwise' forces plain | to numeric.

voodoo89 tybalt89 looks around for more chickens...

[LanX]

> Most probable reason you are seeing what you saw -> you did "use feature 'bitwise'" earlier in your debugging session. bitwise forces plain | to numeric.

There was no "use feature 'bitwise'" inside the debugger.

:~$ perl -de0

Loading DB routines from perl5db.pl version 1.77
...
  DB<1> say (0 . "$_" | 1 . "1") for qw/0 2 4 6 8/
11
11
15
15
11

  DB<2>

but the interactive debugger seems to automatically run under -E

E commandline
behaves just like -e, except that it implicitly enables all optional features and builtin functions (in the main compilation unit). See feature and builtin.

[tybalt89]

Good catch!

Quick test: if say 1 |. 2 does NOT give an error, you're running with use feature 'bitwise';

[LanX]

These are the features automatically activated in the debugger

    use feature 'current_sub', 'bitwise', 'evalbytes', 'fc', 'isa', 'p
+ostderef_qq', 'say', 'signatures', 'state', 'unicode_strings', 'unico
+de_eval';

Tested for 5.036000.

[harangzsolt33]

Wait. Are you saying that if someone has "use feature 'bitwise' in their header, then this code fails? How do I make sure it doesnt? Can I write "no feature 'bitwise';" inside binary2decimal() to make sure it doesn't misbehave? Or is that unnecessary?

[LanX]

> Wait. Are you saying that if someone has "use feature bitwise in their header, then this code fails?

If it's in the same scope, yes.

Not sure what header means for you.

> Can I write "no feature 'bitwise';" inside binary2decimal() to make sure it doesn't misbehave?

Theoretically yes, try it out.

Better use feature bitwise and change the operator to |. ... But this wouldn't work in older Perl.

So in case backwards compatibility is an issue, maybe no combined with if Version >...

In general, if someone was copying that code into his scope, you shouldn't be bothered about their fate. It's their responsibility.

The right approach of sharing code is to use modules, not boilerplating.