{"id":32460,"date":"2021-05-12T17:07:56","date_gmt":"2021-05-12T21:07:56","guid":{"rendered":"https:\/\/mjtsai.com\/blog\/?p=32460"},"modified":"2021-06-18T15:52:12","modified_gmt":"2021-06-18T19:52:12","slug":"fixing-swifts-if-let-syntax","status":"publish","type":"post","link":"https:\/\/mjtsai.com\/blog\/2021\/05\/12\/fixing-swifts-if-let-syntax\/","title":{"rendered":"Fixing Swift’s “if let” Syntax"},"content":{"rendered":"

Craig Hockenberry<\/a> (tweet<\/a>):<\/p>\n

The if-let syntax discourages long variable names because there’s no autocomplete for optional variables that are in scope. It’s not uncommon to see things like this because programmers are notoriously lazy:<\/p>

if let favc = fooAutomationViewController { … }<\/pre>
Any code within that block that references favc won’t be very readable.<\/p>
This maintenance issue is exacerbated by name refactoring. Say you want to change fooAutomationViewController to a barAutomatedViewController. The refactored code will then become:<\/p>
if let favc = barAutomatedViewController { … }<\/pre><\/blockquote>\n
The if let fooAutomationViewController = fooAutomationViewController<\/code> repetition is one of the more annoying things about writing and reading Swift. Allowing this to be written as just if let fooAutomationViewController<\/code> seems like the obvious solution. For those arguing that this is confusing or hard to learn, I don’t see how it’s any less clear than what it would be replacing. That said, I wouldn’t be opposed to something like unwrap<\/a>.<\/p>\n\n
Update (2021-06-18): Marcel Weiher<\/a>:<\/p>\n
When I added ifNotNil:<\/code> some time ago, I used the same logic, but it turns out the object\nis now actually potentially interesting.  So ifNotNil:<\/code> now passes the now-known-to-be-non-nil\nvalue to the block and can be used as follows[…]<\/p>\n
[…]<\/p>
This doesn’t eliminate the duplication, but does avoid the issue of having the newly introduced variable name precede the original variable.  Well, that and the whole\nweird if let<\/code> in the first place.<\/p><\/blockquote>\n
You can do this in Swift by calling map(_:)<\/code> on the optional. It’s useful in some cases, but, since it relies on a closure like forEach(_:)<\/code>, it’s often not a good fit because it doesn’t compose well with other language features (additional optionals to be unwrapped, continue<\/code>, return<\/code>, etc.).<\/p>","protected":false},"excerpt":{"rendered":"
Craig Hockenberry (tweet): The if-let syntax discourages long variable names because there’s no autocomplete for optional variables that are in scope. It’s not uncommon to see things like this because programmers are notoriously lazy:if let favc = fooAutomationViewController { … }Any code within that block that references favc won’t be very readable.This maintenance issue is […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"apple_news_api_created_at":"2021-05-12T21:07:59Z","apple_news_api_id":"04c21a01-44b5-4daf-bf53-f642d39bf230","apple_news_api_modified_at":"2021-06-18T19:52:16Z","apple_news_api_revision":"AAAAAAAAAAAAAAAAAAAAAQ==","apple_news_api_share_url":"https:\/\/apple.news\/ABMIaAUS1Ta-_U_ZC05vyMA","apple_news_coverimage":0,"apple_news_coverimage_caption":"","apple_news_is_hidden":false,"apple_news_is_paid":false,"apple_news_is_preview":false,"apple_news_is_sponsored":false,"apple_news_maturity_rating":"","apple_news_metadata":"\"\"","apple_news_pullquote":"","apple_news_pullquote_position":"","apple_news_slug":"","apple_news_sections":"\"\"","apple_news_suppress_video_url":false,"apple_news_use_image_component":false,"footnotes":""},"categories":[4],"tags":[46,71,901,226],"class_list":["post-32460","post","type-post","status-publish","format-standard","hentry","category-programming-category","tag-languagedesign","tag-programming","tag-swift-programming-language","tag-xcode"],"apple_news_notices":[],"_links":{"self":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/32460","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/comments?post=32460"}],"version-history":[{"count":3,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/32460\/revisions"}],"predecessor-version":[{"id":32898,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/32460\/revisions\/32898"}],"wp:attachment":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/media?parent=32460"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/categories?post=32460"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/tags?post=32460"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}