Thanks Ben ��� it���s all clear now. Thanks also to Esteban, who spared my blushes by answering direct!

Peter Kenny

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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

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On Tue, 11 Sep 2018 at 02:44, PBKResearch <peter@pbkresearch.co.uk> wrote:

Hi All

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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.

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I have seen from examples in this forum that an expression like the following:

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paras collect: [para| para prettyPrinted]

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can be written more concisely as:

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paras collect: #prettyPrinted

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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,

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Its not special notation.�� Just a normal object (a Symbol) passed via a normal message.

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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?

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Any help gratefully received.

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Peter Kenny

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Full answer ;)

Its a combination of the following two methods...

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Collection >> collect: aBlock��

���������������������������� | newCollection |

���������������������������� newCollection := self species new.

���������������������������� self do: [:each | newCollection add: (aBlock value: each)].

���������������������������� ^ newCollection��

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Symbol value: anObject��

���������������������������� ^anObject perform: self.

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When /aBlock/ is a symbol, that symbol is performed on /each/ element.

And looking at�� #select:�� , yes it works the same...��

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Collection >> select: aBlock��

���������������������������� | newCollection |

���������������������������� newCollection := self copyEmpty.

���������������������������� self do: [ :each |��

���������������������������������������������������������� (aBlock value: each)��

���������������������������������������������������������������������������������������� ifTrue: [ newCollection add: each ]].

���������������������������� ^newCollection

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cheers -ben