Static typo checker - Speaker Deck

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4 U B U J D U Z Q P D I F D L F S

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!ZVLJ $PNNJUFS .BJOUBJOFSPGUIFkaminariHFN $SFBUPSPGUIFdid_you_meanHFN : 6 , * / * 4 ) * + * . "

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8 I B U E P F T U I F E J E @ Z P V @ N F B O H F N E P

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"Yuki".starts_with?("Y") # => NoMethodError: undefined method `starts_with?’ for …

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"Yuki".starts_with?("Y") # => NoMethodError: undefined method `starts_with?’ for … # Did you mean? start_with? >= 2.3

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3 F D F O U D I B O H F T J O U I F d i d _ y o u _ m e a n H F N

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%: . ❤ 3 V C Z w %:.BMQIBDPNQBUJCMFXJUIEFW w %:.DPNQBUJCMFXJUIBOEMBUFS w %:.DPNQBUJCMFXJUIBOEMBUFS w %:.GPSBOZFBSMJFSWFSTJPOTPG3VCZ

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4 V H H F T U J P O T P O / B N F & S S P S G S P N S t r u c t # [ ] Struct.new(:name).new[:naem] # => NameError: no member 'naem' in struct # Did you mean? name Struct.new(:name).new[:naem] # => NameError: no member 'naem' in struct Ruby 2.4 and did_you_mean 1.1.2: Ruby 2.3 and did_you_mean 1.0.0:

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$ B M M F E O B N F J T F Y D M V E F E G S P N T V H H F T U J P O T name; name = 1 # => NameError: undefined local variable or method `name' for … # Did you mean? name name; name = 1 # => NameError: undefined local variable or method `name' for … Ruby 2.4 and did_you_mean 1.1.2: Ruby 2.3 and did_you_mean 1.0.0:

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- F T T T V H H F T U J P O T P O / P . F U I P E & S S P S G S P N n i l @users.map {|user| ... } # => NameError: undefined method `map' for nil:NilClass # Did you mean? tap @users.map {|user| ... } # => NameError: undefined method `map' for nil:NilClass Ruby 2.4 and did_you_mean 1.1.2: Ruby 2.3 and did_you_mean 1.0.0:

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1 S J W B U F N F U I P E T B S F O P M P O H F S T V H H F T U F E X I F O O P U D B M M B C M F File.raed 'path/to/file.csv' # => NoMethodError: undefined method `raed' for File:Class # Did you mean? read # rand File.raed 'path/to/file.csv' # => NoMethodError: undefined method `raed' for File:Class # Did you mean? read Ruby 2.4 and did_you_mean 1.1.2: Ruby 2.3 and did_you_mean 1.0.0:

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& Y Q F S J N F O U B M G F B U V S F T

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$ gem i did_you_mean -v=1.1.2 require 'did_you_mean/experimental'

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@full_name = "Yuki Nishijima" @full_anme.split(" ") # => NoMethodError: undefined method `split' for nil:NilClass 5ZQP

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require 'did_you_mean/experimental' @full_name = "Yuki Nishijima" @full_anme.split(" ") # => NoMethodError: undefined method `split' for nil:NilClass # Did you mean? @full_name

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hash = {"name" => "Yuki"} hash.fetch("anme") # KeyError: key not found: "anme" 5ZQP

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require 'did_you_mean/experimental' hash = {"name" => "Yuki"} hash.fetch("anme") # KeyError: key not found: "anme" # Did you mean? "name"

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class User def iniialize(name, ...) ... end end User.new("Yuki Nishijima", ...) # => ArgumentError: wrong number of arguments … 5ZQP

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require 'did_you_mean/experimental' class User def iniialize(name, ...) ... end end # => warning: iniialize might be misspelled, perhaps you meant initialize? User.new("Yuki Nishijima", ...) # => ArgumentError: wrong number of arguments …

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4 Q F M M D I F D L F S B T B Q V C M J D " 1 * checker = DidYouMean::SpellChecker.new(dictionary: methods) checker.correct(‘sedn') # => [‘send']

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+ 3 V C Z T V Q Q P S U $ irb > RUBY_ENGINE # => "jruby" > RUBY_DESCRIPTION # => "jruby 9.1.3.0 (2.3.1) 2016-08-29 a2a3b29 Java HotSpot(TM) 64-Bit Server VM 25.121-b13 on 1.8.0_121-b13 +jit [darwin-x86_64]” > "Yuki".starts_with?("Y") # => NoMethodError: undefined method `starts_with?' for … Did you mean? start_with?

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1 S P C M F N T J O U I F d i d _ y o u _ m e a n H F N

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3 V O U J N F M P P L V Q

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- P B E J O H :P V S " Q Q M J D B U J P O w 3VCZDPSF .3* +3VCZ 3VCJOJVT FUD w 3VCZHFNT OPUHFNT w :PVSDPEF w %FQFOEFODJFT TUEMJC HFNT w :PVSBQQ`TDMBTTFTNPEVMFT w .FUBQSPHSBNNJOH #define_method #eval w 0UIFSXPSLJGOFDFTTBSZ FHMJTUFOJOHUPBQPSU

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3 V O O J O H :P V S " Q Q M J D B U J P O w 8FCTFSWFSSFDFJWFTBSFRVFTU w 3FRVFTUJTQBTTFEJOUPrack w 3FRVFTUHPFTUISPVHISBDLNJEEMFXBSF w 3FRVFTUIJUTUIF3BJMTDPOUSPMMFS w $POUSPMMFSHFOFSBUFTBSFTQPOTF w %# )551DBMMT DBDIJOH MPHHJOH )5.- FUD w 4FOEFWFSZUIJOHCBDLUPUIFDMJFOU

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w 8FCTFSWFSSFDFJWFTBSFRVFTU w 3FRVFTUJTQBTTFEJOUPrack w 3FRVFTUHPFTUISPVHIrack middleware w 3FRVFTUIJUTUIFRailsDPOUSPMMFS w $POUSPMMFSHFOFSBUFTBSFTQPOTF w %# )551DBMMT DBDIJOH MPHHJOH )5.- FUD w 4FOEFWFSZUIJOHCBDLUPUIFDMJFOU w 3VCZDPSF .3* +3VCZ 3VCJOJVT FUD w 3VCZHFNT OPUHFNT w :PVSDPEF w %FQFOEFODJFT TUEMJC HFNT w :PVSDMBTTFTNPEVMFT w .FUBQSPHSBNNJOH #define_method #eval w 0UIFSXPSLJGOFDFTTBSZ FHMJTUFOJOHUPBQPSU

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w 3VCZDPSF .3* +3VCZ 3VCJOJVT FUD w 3VCZHFNT OPUHFNT w :PVSDPEF w %FQFOEFODJFT TUEMJC HFNT w :PVSDMBTTFTNPEVMFT w .FUBQSPHSBNNJOH #define_method #eval w 0UIFSXPSLJGOFDFTTBSZ FHMJTUFOJOHUPBQPSU w 8FCTFSWFSSFDFJWFTBSFRVFTU w 3FRVFTUJTQBTTFEJOUPrack w 3FRVFTUHPFTUISPVHIrack middleware w 3FRVFTUIJUTUIFRailsDPOUSPMMFS w $POUSPMMFSHFOFSBUFTBSFTQPOTF w %# )551DBMMT DBDIJOH MPHHJOH )5.- FUD w NoMethodErrorPDDVST w did_you_meanTVHHFTUTBNFUIPEOBNF

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4 U B U J D B O B M Z T J T U P U I F S F T D V F

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d i d _ y o u _ m e a n / s t a t i c require 'did_you_mean/undefined_method_detector' PROJECT_DIR = Dir.pwd at_exit { UndefinedMethodDetector.new(PROJECT_DIR) .undefined_methods .each { |method| method.called_by.each { |caller| puts "`#{method.name}' seems undefined but is called at " \ "#{caller.source_location[0]}:#{method.lineno}" } } }

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require 'did_you_mean/undefined_method_detector' class Foo def bar i_do_not_exist end end UndefinedMethodDetector.new(Dir.pwd).undefined_methods.first.name # => ‘i_do_not_exist’

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1B S T F S

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1B S T F S w Ripper w UIFQBSTFSHFN w RubyVM::InstructionSequence CZUFDPEF

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w Ripper w UIFQBSTFSHFN w RubyVM::InstructionSequence CZUFDPEF 1B S T F S

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class Foo def bar i_do_not_exist end end

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require ‘pp' pp RubyVM::InstructionSequence.compile(<<-CODE).to_a[13] class Foo def bar i_do_not_exist end end CODE # => bytecode

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require ‘pp' pp RubyVM::InstructionSequence.compile(<<-CODE).to_a[13] class Foo def bar i_do_not_exist end end CODE # => bytecode [1, [:trace, 1], [:putspecialobject, 3], [:putnil], [:defineclass, :Foo, ["YARVInstructionSequence/SimpleDataFormat", 2, 3, 1, {:arg_size=>0, :local_size=>0, :stack_max=>3}, "", "", nil, 1, :class, [], {}, [], [1, [:trace, 2], 2, [:trace, 1], [:putspecialobject, 1], [:putobject, :bar], [:putiseq, ["YARVInstructionSequence/SimpleDataFormat", 2, 3, 1, {:arg_size=>0, :local_size=>0, :stack_max=>1}, "bar", "", nil, 2, :method, [], {}, [], [2, [:trace, 8], 3, [:trace, 1], [:putself], [:opt_send_without_block, {:mid=>:i_do_not_exist, :flag=>28, :orig_argc=>0}, false], 4, [:trace, 16], 3, [:leave]]]], [:opt_send_without_block, {:mid=>:"core#define_method", :flag=>16, :orig_argc=>2}, false], 5, [:trace, 4], 2, [:leave]]], 0], [:leave]]

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class Foo def bar i_do_not_exist end end [:defineclass, :Foo, […,

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class Foo def bar i_do_not_exist end end [:defineclass, :Foo, […, […, [:putobject, :bar], […,

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class Foo def bar i_do_not_exist end end [:defineclass, :Foo, […, […, [:putobject, :bar], […, …, …, [:opt_send_without_block, {:mid=>:i_do_not_exist, :flag=>28, :orig_argc=>0}, false], …,]]]]

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$ B M M B C M F N F U I P E T • Foo.instance_methods • Foo.private_instance_methods

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$ B M M B C M F N F U I P E T • Foo.instance_methods • Foo.private_instance_methods l*TO`UUIBU3VCZDPEF z"

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require 'did_you_mean/undefined_method_detector' class Foo def bar i_do_not_exist end end UndefinedMethodDetector.new(Dir.pwd).undefined_methods.first.name # => ‘i_do_not_exist’

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require 'did_you_mean/undefined_method_detector' class Foo def bar i_do_not_exist end end UndefinedMethodDetector.new(Dir.pwd).undefined_methods.first.name # => ‘i_do_not_exist’ # won’t be executed

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1 S P C M F N T w /PUFOUJSFMZTUBUJD w 0OMZTLJQTFYFDVUJOHJOTUBODFNFUIPET w $MBTTFTBOENPEVMFTOFFEUPCFMPBEFE w ,FSOFMNFUIPETDBOCFDBMMBCMF #eval #exit FUD

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& E J U P S J O U F H S B U J P O

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VSCode fires a command on file save (JavaScript) returns JSON through stdout

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" D U J W B U F 7 4 $ P E F Q M V H J O export function activate(context: ExtensionContext) { … const window = vscode.window const subscription = window.onDidChangeActiveTextEditor(executeSpellChecking) context.subscriptions.push(subscription) }

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function executeSpellChecking( editor: vscode.TextEditor | vscode.TextDocumentChangeEvent) { if (!editor || editor.document.isDirty) return const projectDir = vscode.workspace.rootPath const fileToCheck = editor.document.uri.path … cp.exec( `ruby -rdid_you_mean/static -Ilib ${fileToCheck}`, { cwd: projectDir }, (err, stdout, stderr) => { const result = JSON.parse(stdout) // => result from DYM // Annotate undefined methods using VSCode API }) }

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{ "ruby_engine": "ruby", "ruby_version": "2.5.0", "ruby_description": "ruby 2.5.0dev (2017-06-28 trunk 59186) …”, "did_you_mean_version": "1.2.0-alpha", "undefined_names": { "9": [ { "undefined_name": "raiae", "symbol_type": "method", "path": "/did_you_mean/test/spell_checking/method_name_test.rb", "lineno": 9, "suggestions": [ "raise" ] } ], … }

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require 'did_you_mean/undefined_method_detector' PROJECT_DIR = Dir.pwd at_exit { UndefinedMethodDetector.new(PROJECT_DIR) .undefined_methods .each { |method| method.called_by.each { |caller| puts "`#{method.name}' seems undefined but is called at " \ "#{caller.source_location[0]}:#{method.lineno}" } } }

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$ V S S F O U T U B U F w /PUFOUJSFMZTUBUJD w 5PPNBOZGBMTFQPTJUJWFT w /PUGBTUFOPVHIGPSMBSHFQSPKFDUT w 3BJMT

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4 X J U D I J O H U P T U B U J D B O B M Z T J T w 5FDIOJDBMMZQPTTJCMF w NBZNBLFJUJOBDDVSBUF

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8 I Z N B O Z G B M T F Q P T J U J W F T w %ZOBNJDBMMZEFpOFENFUIPET w $BMMTIBOEMFECZ#method_missing w %VDLUZQJOH

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Not defined within the gem Found in the doc

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Static typo checker YARD filter Editor filters out method names found in RDoc

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8 I Z T M P X w 5PPNBOZEFQFOEFODJFTUPMPBE w 'JOEJOHTVHHFTUJPOTJTTMPX

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3BJMT needs significant amount of work aside from the rest of the work

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$ P O D M V T J P O w 4UJMMJOFBSMZTUBHF CVUXPSLTXFMMGPSTNBMMQSPKFDUT w 5ZQFTZTUFNXJMMIFMQ CVUTFFNTUPPBNCJUJPVTBUUIJT QPJOU w 4UBUJDBOBMZTJT PS"45 JTFYUSFNFMZQPXFSGVM

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5IBOLZPV