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Re: Fixes boolean/SCM confusions, part 1. (issue 4875054)

From: dak
Subject: Re: Fixes boolean/SCM confusions, part 1. (issue 4875054)
Date: Thu, 18 Aug 2011 21:04:25 +0000

On 2011/08/18 18:01:36, Carl wrote:
On 2011/08/18 15:46:43, dak wrote:

> lily/ if (scm_is_true (tr->get_property
> ("ignoreBarChecks")))
> As I already explained: you can't replace to_boolean with
scm_is_true, since
> to_boolean( '() ) -> 0, whereas scm_is_true ( '() ) -> 1 (I
apologize for the
> mixture of X and Scheme syntax), and '() is _definitely_ one value
that needs
> be interpreted as false in the context of boolean properties.

It depends.  If you want to have unset properties default to #t, then
scm_is_true is correct.

If you want to have them default to #f, then to_boolean is clearly the
way to go.

If you want to have a different default, depending on the property,
then we
should have a robust_scm2bool that should be used in these cases.

Well, if we have properties that should default to #t (do we really have
any of those?) then we should likely use something like to_boolean_or_t
and to_boolean_or_f instead of scm_is_true and to_boolean.  Using the
latter is far too obscure and does not make the programmer's intention

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