Its a very interesting and elegant aspect of Pharo and I'm sure there are others at different parts of their journey learning Pharo who learnt something new from your question.
cheers -ben On Tue, 11 Sep 2018 at 03:13, PBKResearch <pe...@pbkresearch.co.uk> wrote: > Thanks Ben – it’s all clear now. Thanks also to Esteban, who spared my > blushes by answering direct! > > Peter Kenny > > > > *From:* Pharo-users <pharo-users-boun...@lists.pharo.org> *On Behalf Of *Ben > Coman > *Sent:* 10 September 2018 19:56 > *To:* Any question about pharo is welcome <pharo-users@lists.pharo.org> > *Subject:* Re: [Pharo-users] Query on Pharo syntax > > > > > > On Tue, 11 Sep 2018 at 02:44, PBKResearch <pe...@pbkresearch.co.uk> wrote: > > Hi All > > > > This is an idiot question, I should know the answer, but I have looked > around and can’t find relevant documentation. I’m not asking for a full > answer, just a pointer as to where to start looking. > > > > I have seen from examples in this forum that an expression like the > following: > > > > paras collect: [para| para prettyPrinted] > > > > can be written more concisely as: > > > > paras collect: #prettyPrinted > > > > which obviously works when I try it. It doesn’t seem to fit in with the > definition of #collect:, which requires a block as argument. Where can I > find the relevant definition, either in method comments or in some general > manual? Can the notation be extended, > > > > Its not special notation. Just a normal object (a Symbol) passed via a > normal message. > > > > for example to #select: - obviously with an argument which returns a > Boolean? Can it be used with a method which requires an argument, e.g. as > myArray collect: (#myMethod: arg)? Are there any other extensions? > > > > Any help gratefully received. > > > > Peter Kenny > > > > Full answer ;) > > Its a combination of the following two methods... > > > > Collection >> collect: aBlock > > | newCollection | > > newCollection := self species new. > > self do: [:each | newCollection add: (aBlock value: each)]. > > ^ newCollection > > > > Symbol value: anObject > > ^anObject perform: self. > > > > When /aBlock/ is a symbol, that symbol is performed on /each/ element. > > And looking at #select: , yes it works the same... > > > > Collection >> select: aBlock > > | newCollection | > > newCollection := self copyEmpty. > > self do: [ :each | > > (aBlock value: each) > > ifTrue: [ newCollection add: > each ]]. > > ^newCollection > > > > cheers -ben >
