but you should use myCollection ifEmpty: [ ... ] Phil
On Mon, Oct 31, 2016 at 3:25 PM, Sven Van Caekenberghe <s...@stfx.eu> wrote: > myCollection isEmpty ifTrue: [ self inform: 'The collection is empty' ]. > > First #isEmpty is sent to myCollection which results in either true or > false as value. > > Then #ifTrue: is sent to this value. > > Now, if the value was true (the sole instance of class True), the code in > True>>#ifTrue: is executed, which will evaluate the block by sending it > #value. If the value was false, the code in False>>#ifTrue: is executed, > and nil is returned and the block is not executed. > > Like others said, it is just polymorphism at work. > > (And yes, the compiler optimises some of this logic a bit, but the effect > is the same). > > > On 31 Oct 2016, at 14:58, CodeDmitry <dimamakh...@gmail.com> wrote: > > > > But still, how is the actual argument "alternativeBlock" passed to the > > True/False from a Boolean? > > > > The message does not cache the message inside itself before passing the > > message, and it does not pass the alternative block along with the > message. > > > > > > > > -- > > View this message in context: http://forum.world.st/How- > does-Boolean-ifTrue-work-tp4920873p4920886.html > > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. > > > > > >
