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 <peter@pbkresearch.co.uk> wrote:
Thanks Ben â itâs all clear now. Thanks also to Esteban, who spared my blushes by answering direct!
Peter Kenny
*From:* Pharo-users <pharo-users-bounces@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 <peter@pbkresearch.co.uk> wrote:
Hi All
This is an idiot question, I should know the answer, but I have looked around and canât find relevant documentation. Iâm 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 doesnât 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