Re: [Pharo-users] Query on Pharo syntax
I learned something for sure from this exchange. Thanks Peter and Ben for this public conversation. Cheers, Offray On 9/10/18 7:56 PM, Ben Coman wrote: > 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 <mailto: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 <mailto:pharo-users-boun...@lists.pharo.org>> *On Behalf Of *Ben Coman > *Sent:* 10 September 2018 19:56 > *To:* Any question about pharo is welcome > mailto:pharo-users@lists.pharo.org>> > *Subject:* Re: [Pharo-users] Query on Pharo syntax > > > > > > On Tue, 11 Sep 2018 at 02:44, PBKResearch <mailto: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 >
Re: [Pharo-users] Query on Pharo syntax
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 wrote: > Thanks Ben – it’s all clear now. Thanks also to Esteban, who spared my > blushes by answering direct! > > Peter Kenny > > > > *From:* Pharo-users *On Behalf Of *Ben > Coman > *Sent:* 10 September 2018 19:56 > *To:* Any question about pharo is welcome > *Subject:* Re: [Pharo-users] Query on Pharo syntax > > > > > > On Tue, 11 Sep 2018 at 02:44, PBKResearch 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 >
Re: [Pharo-users] Query on Pharo syntax
Thanks Ben – it’s all clear now. Thanks also to Esteban, who spared my blushes by answering direct! Peter Kenny From: Pharo-users On Behalf Of Ben Coman Sent: 10 September 2018 19:56 To: Any question about pharo is welcome Subject: Re: [Pharo-users] Query on Pharo syntax On Tue, 11 Sep 2018 at 02:44, PBKResearch mailto: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
Re: [Pharo-users] Query on Pharo syntax
On Tue, 11 Sep 2018 at 02:44, PBKResearch 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
[Pharo-users] Query on Pharo syntax
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, 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
