My opinion: for scripting ok, for the general language not yet convinced.
`notNil and: []` + `isNil or: []` are only slightly longer and somehow
easier to read for me. Remain the block arguments; I also find myself
avoiding temporaries sometimes, but Levente is right that they are the
idiomatic way to to this, not in:-like constructs: (xyz := ...) notNil and:
[xyz ...]

Maybe one should rather refactor the candidate senders to use less nils? Or
guard against nil at the top if possible?

Have you had a look at Java 8's Optional class? Nil can receive messages in
Smalltalk, which Java null can't. Is nil therefore a good empty Optional or
should these concepts be separate?

Thiede, Christoph <Christoph.Thiede at student.hpi.uni-potsdam.de> schrieb am
Mo., 16. März 2020, 19:58:

> Hi all,
>
>
> after the release has been managed successfully, I would like to
> kindly push this proposal. In the latest months, I found myself to really
> often desiring #isNilOr: or #notNilAnd:. How would you think about these
> convenience selectors? :-)
>
>
> Best,
>
> Christoph
> ------------------------------
> *Von:* Thiede, Christoph
> *Gesendet:* Mittwoch, 11. Dezember 2019 11:01:44
> *An:* Squeak Dev
> *Betreff:* #isNilOr:, #notNilAnd:
>
>
> Hi all, just another idea for a hypothetic extension to ProtoObject:
>
>
> ProtoObject >> #isNilOr: aBlock
>
> ^ aBlock cull: self
>
> UndefinedObject >> #isNilOr: aBlock
>
> ^ true
>
> ProtoObject >> #notNilAnd: aBlock
>
> ^ aBlock cull: self
>
> UndefinedObject >> #notNilAnd: aBlock
>
> ^ false
>
>
> Examples:
>
> parentObject notNilAnd: #canBrowseSubtopic.
>
> helpClass notNilAnd: [:hC| hC usesCodeStyling].
>
> self selectionIndex isNilOr: [:index | index > 2].
>
> anObject isNilOr: #isZero.
>
> foo isNilOr: #isNotEmpty.
>
> Just a bit syntactic sugar for idiomatic problems such as below. In
> particular, I found several possible applications for #notNilAnd: in my
> image.
>
>
> Go ahead and tell me why it would be a bad idea :)
>
>
> Best,
>
> Christoph
>
> ------------------------------
> *Von:* Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im
> Auftrag von Thiede, Christoph
> *Gesendet:* Freitag, 25. Oktober 2019 19:21 Uhr
> *An:* gettimothy via Squeak-dev
> *Betreff:* Re: [squeak-dev] The Inbox: HelpSystem-Core-ct.123.mcz
>
>
> If you're needing a decision, I'd vote for option 3.
>
> ------------------------------
> *Von:* Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im
> Auftrag von Taeumel, Marcel
> *Gesendet:* Mittwoch, 16. Oktober 2019 11:14:15
> *An:* gettimothy via Squeak-dev
> *Betreff:* Re: [squeak-dev] The Inbox: HelpSystem-Core-ct.123.mcz
>
> Quick suggestion on the formatting. This one:
>
> ^ self canBrowseTopic or: [
>   parentTopic ifNotNil: #canBrowseSubtopic ifNil: [false]]
>
> could become:
>
> ^ self canBrowseTopic or: [
>   parentTopic
> ifNil: [false]
> ifNotNil: [:topic | topic canBrowseSubtopic]]
>
> or:
>
> ^ self canBrowseTopic
>       or: [parentTopic notNil and: [parentTopic canBrowseSubtopic]]
>
> Hmmm... what are other opinions on this? There is no need for
> #ifNil/ifNotNil in such a boolean expression?
>
> Best,
> Marcel
>
>
> Am 13.10.2019 21:04:19 schrieb commits at source.squeak.org <
> commits at source.squeak.org>:
> A new version of HelpSystem-Core was added to project The Inbox:
> http://source.squeak.org/inbox/HelpSystem-Core-ct.123.mcz
>
> ==================== Summary ====================
>
> Name: HelpSystem-Core-ct.123
> Author: ct
> Time: 13 October 2019, 9:04:08.373932 pm
> UUID: dec7ceca-320f-d945-8d2a-c2f6a5e49a52
> Ancestors: HelpSystem-Core-ct.120
>
> Refactors HelpBrowser menu: Move menu stuff from HelpBrowser into
> HelpTopic hierarchy in favor of a better object design
>
> Thanks again, Marcel :-)
>
> =============== Diff against HelpSystem-Core-ct.120 ===============
>
> Item was added:
> + ----- Method: AbstractHelpTopic>>browseTopicFromParent: (in category
> 'tools') -----
> + browseTopicFromParent: parentTopic
> +
> + self canBrowseTopic
> + ifTrue: [^ self browseTopic].
> + parentTopic canBrowseSubtopic
> + ifTrue: [^ parentTopic browseSubtopic: self].
> + !
>
> Item was added:
> + ----- Method: AbstractHelpTopic>>canBrowseSubtopic (in category
> 'testing') -----
> + canBrowseSubtopic
> +
> + ^ false!
>
> Item was added:
> + ----- Method: AbstractHelpTopic>>canBrowseTopic (in category 'testing')
> -----
> + canBrowseTopic
> +
> + ^ false!
>
> Item was added:
> + ----- Method: AbstractHelpTopic>>canBrowseTopicFromParent: (in category
> 'testing') -----
> + canBrowseTopicFromParent: parentTopic
> +
> + ^ self canBrowseTopic or: [
> + parentTopic ifNotNil: #canBrowseSubtopic ifNil: [false]]!
>
> Item was added:
> + ----- Method: AbstractHelpTopic>>topicMenu:parentTopic: (in category
> 'menus') -----
> + topicMenu: aMenu parentTopic: parentTopic
> +
> + aMenu
> + add: 'Inspect (i)' translated target: self action: #inspect;
> + add: 'Explore (I)' translated target: self action: #explore.
> + (self canBrowseTopicFromParent: parentTopic)
> + ifTrue: [
> + aMenu add: 'Browse (b)' translated
> + target: self
> + selector: #browseTopicFromParent:
> + argumentList: {parentTopic} ].
> +
> + ^ aMenu!
>
> Item was added:
> + ----- Method: AbstractHelpTopic>>topicMenuKey:fromParent: (in category
> 'menus') -----
> + topicMenuKey: aChar fromParent: parentTopic
> +
> + aChar
> + caseOf: {
> + [$b] -> [(self canBrowseTopicFromParent: parentTopic)
> + ifTrue: [ self browseTopicFromParent: parentTopic ]].
> + [$i] -> [self inspect].
> + [$I] -> [self explore] }
> + otherwise: [^ false].
> + ^ true!
>
> Item was added:
> + ----- Method: ClassAPIHelpTopic>>canBrowseTopic (in category 'testing')
> -----
> + canBrowseTopic
> +
> + ^ true!
>
> Item was added:
> + ----- Method: ClassBasedHelpTopic>>canBrowseSubtopic (in category
> 'testing') -----
> + canBrowseSubtopic
> +
> + ^ true!
>
> Item was added:
> + ----- Method: ClassBasedHelpTopic>>canBrowseTopic (in category
> 'testing') -----
> + canBrowseTopic
> +
> + ^ true!
>
> Item was added:
> + ----- Method: DirectoryBasedHelpTopic>>canBrowseTopic (in category
> 'testing') -----
> + canBrowseTopic
> +
> + ^ true!
>
> Item was added:
> + ----- Method: FileBasedHelpTopic>>canBrowseTopic (in category 'testing')
> -----
> + canBrowseTopic
> +
> + ^ true!
>
> Item was removed:
> - ----- Method: HelpBrowser>>browseTopic (in category 'actions') -----
> - browseTopic
> -
> - ^ (self currentTopic respondsTo: #browseTopic)
> - ifTrue: [self currentTopic browseTopic]
> - ifFalse: [self currentParentTopic browseSubtopic: self currentTopic]!
>
> Item was removed:
> - ----- Method: HelpBrowser>>canBrowseTopic (in category 'testing') -----
> - canBrowseTopic
> -
> - ^ (self currentTopic respondsTo: #browseTopic)
> - or: [self currentParentTopic respondsTo: #browseSubtopic:]!
>
> Item was removed:
> - ----- Method: HelpBrowser>>exploreTopic (in category 'actions') -----
> - exploreTopic
> -
> - ^ self currentTopic explore!
>
> Item was removed:
> - ----- Method: HelpBrowser>>inspectTopic (in category 'actions') -----
> - inspectTopic
> -
> - ^ self currentTopic inspect!
>
> Item was changed:
> ----- Method: HelpBrowser>>treeKey:from:event: (in category 'menus') -----
> treeKey: aChar from: aView event: anEvent
>
> anEvent anyModifierKeyPressed ifFalse: [^ false].
> + ^ (self currentTopic topicMenuKey: aChar fromParent: self
> currentParentTopic)!
> - aChar
> - caseOf: {
> - [$b] -> [self browseTopic].
> - [$i] -> [self inspectTopic].
> - [$I] -> [self exploreTopic]. }
> - otherwise: [^ false].
> - ^ true!
>
> Item was changed:
> ----- Method: HelpBrowser>>treeListMenu: (in category 'menus') -----
> treeListMenu: aMenu
>
>
> + ^ self currentTopic
> + ifNil: [aMenu]
> + ifNotNil: [:topic | topic
> + topicMenu: aMenu
> + parentTopic: self currentParentTopic]!
> - self currentTopic ifNil: [^ aMenu].
> -
> - aMenu
> - add: 'Inspect (i)' action: #inspectTopic;
> - add: 'Explore (I)' action: #exploreTopic.
> -
> - self canBrowseTopic ifTrue: [
> - aMenu
> - addLine;
> - add: 'Browse (b)' action: #browseTopic].
> -
> - ^ aMenu!
>
> Item was added:
> + ----- Method: MethodListHelpTopic>>canBrowseTopic (in category
> 'testing') -----
> + canBrowseTopic
> +
> + ^ true!
>
> Item was added:
> + ----- Method: PackageAPIHelpTopic>>canBrowseTopic (in category
> 'testing') -----
> + canBrowseTopic
> +
> + ^ true!
>
>
>
>
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