YAML's No in Perl

dgaramond2 has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: YAML's No in Perl by audreyt (Hermit) on Mar 13, 2006 at 19:12 UTC
`use YAML::Syck; $YAML::Syck::ImplicitTyping = 1; Load("No"); # undef` [download] I had ImplicitTyping on, but Ingy told me it should be off by default to save time and reduce confusion and improve compatibility. So... Blame him. :-)	[reply] [d/l]
Re^2: YAML's No in Perl by dgaramond2 (Monk) on Mar 14, 2006 at 01:27 UTC
Hi audrey. Save time? Execution time? Please explain... I think YAML::Syck is fast enough for all of my needs. Improve compatibility with what, older Perl modules (all of which are 'alpha' or 'beta' and should not guarantee API/backwards compatibility anyway)? I would vote for better interoperability with the other YAML-using languages, as it is one of YAML's biggest strength. Reduce confusion? Hm, that's not what I experienced. Implicit typing is also one of YAML's basic features. So, turn it and keep it on please :)	[reply]
Re^3: YAML's No in Perl by audreyt (Hermit) on Mar 14, 2006 at 12:45 UTC
Okay, I did add a prominient notice to YAML::Syck 0.38 and credited you for it in the ChangeLog. Thanks!	[reply]
Re^4: YAML's No in Perl by dgaramond2 (Monk) on Mar 15, 2006 at 03:02 UTC
Re^2: YAML's No in Perl by bsb (Priest) on Jul 23, 2006 at 23:49 UTC
I think Ingy's right, implicit typing should be off by default. It caused all kinds of bugs including turning an md5 hash string that happened to match /^\d+e\d+$/ into NaN. Implicit typing should only be enabled if it doesn't interfere with round-tripping, Perl's polymorphic scalars seem to me to make this impossible. ImplicitTyping--	[reply]
Re: YAML's No in Perl by adrianh (Chancellor) on Mar 13, 2006 at 12:06 UTC
Strangely, all of them but Perl have had no problem with No being false, but interestingly in Perl we are confused every now and then and load No as the string 'No'. What's going on here? :-) Bugs from the sound of it. I'm sure the developers would love a nicely wrapped up test case and an RT bug report :-)	[reply]
Re: YAML's No in Perl by wazoox (Prior) on Mar 13, 2006 at 12:11 UTC
Perl evaluates 0, `undef` and '' (empty string) as false in scalar context. It evaluates () (empty list) as false in list context. Any other string evaluates as true. I don't see what's wrong with that; if "No" evaluates false, what about "NO", "no", "N" ? What about "Non", "Niet", "Nein" and "La'" ?	[reply] [d/l]
Re^2: YAML's No in Perl by adrianh (Chancellor) on Mar 13, 2006 at 12:22 UTC
I don't see what's wrong with that; if "No" evaluates false, what about "NO", "no", "N" ? What about "Non", "Niet", "Nein" and "La'" ? In YAML it can be a representation of a boolean value - see Boolean Language-Independent Type for YAML™ Version 1.1 for details. So it can make sense for a YAML parser to translate this to a false value in Perl land.	[reply]
Re^3: YAML's No in Perl by wazoox (Prior) on Mar 13, 2006 at 16:17 UTC
I see. It could be then a nice feature to add to the YAML module. After all, it's only an alpha release : latest is 0.58.	[reply]
Re^4: YAML's No in Perl by diotalevi (Canon) on Mar 13, 2006 at 19:12 UTC