Re: When does '123' become the number 123.0?

You could consider the contents of a Perl scalar to be a quantum superposition of string and numeric states which are resolved when you look at them. :-)

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Comment on Re: When does '123' become the number 123.0?

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Re^2: When does '123' become the number 123.0? by quester (Vicar) on Jun 17, 2008 at 06:03 UTC
But unlike real quanta, reading a Perl variable doesn't force it to collapse into only one state. To make this more concrete, note that converting a number (either integer or floating point) to a string leaves both the numeric AND string values marked as valid: `$ perl -MDevel::Peek -wle '$x=12345; print Dump $x; print "$x"; print +Dump $x' SV = IV(0x1004f958) at 0x1004f958 REFCNT = 1 FLAGS = (IOK,pIOK) IV = 12345 12345 SV = PVIV(0x10023810) at 0x1004f958 REFCNT = 1 FLAGS = (IOK,POK,pIOK,pPOK) IV = 12345 PV = 0x10040c08 "12345"\0 CUR = 5 LEN = 8` [download] The same thing works for string to numeric conversions, so `$x="12345.67"; $y=$x+1;` [download] leaves $x with a floating point value and a string value which are both valid. Not only is the Perl implementation Doing What I Mean, by caching the results before it even occurs to me that it would be a good idea it's Doing What I Should Have Meant!	[reply] [d/l] [select]

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Re^2: When does '123' become the number 123.0?
by quester (Vicar) on Jun 17, 2008 at 06:03 UTC

But unlike real quanta, reading a Perl variable doesn't force it to collapse into only one state.

To make this more concrete, note that converting a number (either integer or floating point) to a string leaves both the numeric AND string values marked as valid:

$ perl -MDevel::Peek -wle '$x=12345; print Dump $x; print "$x"; print 
+Dump $x'
SV = IV(0x1004f958) at 0x1004f958
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 12345

12345
SV = PVIV(0x10023810) at 0x1004f958
  REFCNT = 1
  FLAGS = (IOK,POK,pIOK,pPOK)
  IV = 12345
  PV = 0x10040c08 "12345"\0
  CUR = 5
  LEN = 8
[download]

$x="12345.67"; $y=$x+1;
[download]

Not only is the Perl implementation Doing What I Mean, by caching the results before it even occurs to me that it would be a good idea it's Doing What I Should Have Meant!

[reply]
[d/l]
[select]