Hi Dmitry, You've just bumped into one of Smalltalk's paradigms that
may change the way you *think* about programming ;). For me it was
certainly an eye-opener. It intrigued me there could even exist
another way to *think* about booleans.
On Mon, Oct 31, 2016 at 10:06 PM, jtuc...@objektfabrik.de
<jtuc...@objektfabrik.de> wrote:
> When I teach Smalltalk, this is one of the most beautiful exercises for
> students.
> Those who get it will love Smalltalk, those who don't often leave the
> project soon ;-)
Interesting insight.
On Mon, Oct 31, 2016 at 10:32 PM, CodeDmitry <dimamakh...@gmail.com> wrote:
> Boolean seems to indeed just be a "Dynamic Interface"; since Smalltalk does
> not have "Java Interfaces"(nor want them for the same reason JavaScript
> doesn't), the developers wanted to still have True and False be subclasses
> of Booleans.
>
> In all honesty Boolean seems to be there purely for the "common sense" of
> it, rather than need. Smalltalk is duck typed and has no need for
> interfaces. If it's a Boolean, you know it has those methods so Boolean is
> not actually useful for anything; True and False may as well just be
> subclasses of Object.
Not quite. Yes most of Boolean's own methods are mostly
subclassResponsibilitys, but you can see Boolean provides a place for
extensions by *Fuel, *Reflectivity, *ston-core and *UnifiedFFI
packages to hang methods common to both True and False.
The best way to properly understand this is to observe it in action
yourself, by debugging through it.
Except you can't debug it since #ifTrue:#iFalse is inlined for performance.
Instead try defining...
True>>myifTrue: trueAlternativeBlock ifFalse: falseAlternativeBlock
^trueAlternativeBlock value
False>>myifTrue: trueAlternativeBlock ifFalse: falseAlternativeBlock
^falseAlternativeBlock value
then from Playground, debug...
true myifTrue: [self inform: 'true'] ifFalse: [self inform: 'false'].
false myifTrue: [self inform: 'true'] ifFalse: [self inform: 'false'].
and just continue stepping <Into>,
(except step <Over> the #inform: when you get there)
cheers -ben
