Support casks in brew cat.

Library/Homebrew/cli/named_args.rb

@@ -117,7 +117,7 @@ module Homebrew
       private :to_objects
 
       def to_formulae_paths
-        to_paths(only: :formulae)
+        to_paths(only: :formula)
       end
 
       # Keep existing paths and try to convert others to tap, formula or cask paths.
@@ -128,11 +128,11 @@ module Homebrew
         @to_paths[only] ||= downcased_unique_named.flat_map do |name|
           if File.exist?(name)
             Pathname(name)
-          elsif name.count("/") == 1
+          elsif name.count("/") == 1 && !name.start_with?("./", "/")
             Tap.fetch(name).path
           else
-            next Formulary.path(name) if only == :formulae
-            next Cask::CaskLoader.path(name) if only == :casks
+            next Formulary.path(name) if only == :formula
+            next Cask::CaskLoader.path(name) if only == :cask
 
             formula_path = Formulary.path(name)
             cask_path = Cask::CaskLoader.path(name)

Library/Homebrew/dev-cmd/cat.rb

@@ -12,18 +12,27 @@ module Homebrew
   def cat_args
     Homebrew::CLI::Parser.new do
       usage_banner <<~EOS
-        `cat` <formula>
+        `cat` <formula>|<cask>
 
-        Display the source of <formula>.
+        Display the source of a <formula> or <cask>.
       EOS
 
-      named :formula
+      switch "--formula", "--formulae",
+             description: "Treat all named arguments as formulae."
+      switch "--cask", "--casks",
+             description: "Treat all named arguments as casks."
+      conflicts "--formula", "--cask"
+
+      named :formula_or_cask
     end
   end
 
   def cat
     args = cat_args.parse
 
+    only = :formula if args.formula? && !args.cask?
+    only = :cask if args.cask? && !args.formula?
+
     cd HOMEBREW_REPOSITORY
     pager = if Homebrew::EnvConfig.bat?
       ENV["BAT_CONFIG_PATH"] = Homebrew::EnvConfig.bat_config_path
@@ -31,6 +40,7 @@ module Homebrew
     else
       "cat"
     end
-    safe_system pager, args.named.to_formulae_paths.first
+
+    safe_system pager, args.named.to_paths(only: only).first
   end
 end

Library/Homebrew/test/cli/named_args_spec.rb

@@ -150,16 +150,16 @@ describe Homebrew::CLI::NamedArgs do
       expect(described_class.new("foo", "baz").to_paths).to eq [formula_path, cask_path]
     end
 
-    it "returns only formulae when `only: :formulae` is specified" do
+    it "returns only formulae when `only: :formula` is specified" do
       expect(Formulary).to receive(:path).with("foo").and_return(formula_path)
 
-      expect(described_class.new("foo", "baz").to_paths(only: :formulae)).to eq [formula_path, Formulary.path("baz")]
+      expect(described_class.new("foo", "baz").to_paths(only: :formula)).to eq [formula_path, Formulary.path("baz")]
     end
 
-    it "returns only casks when `only: :casks` is specified" do
+    it "returns only casks when `only: :cask` is specified" do
       expect(Cask::CaskLoader).to receive(:path).with("foo").and_return(cask_path)
 
-      expect(described_class.new("foo", "baz").to_paths(only: :casks)).to eq [cask_path, Cask::CaskLoader.path("baz")]
+      expect(described_class.new("foo", "baz").to_paths(only: :cask)).to eq [cask_path, Cask::CaskLoader.path("baz")]
     end
   end
 end

docs/Manpage.md

@@ -915,9 +915,14 @@ present, "revision 1" will be added.
 * `--message`:
   Append *`message`* to the default commit message.
 
-### `cat` *`formula`*
+### `cat` *`formula`*|*`cask`*
 
-Display the source of *`formula`*.
+Display the source of a *`formula`* or *`cask`*.
+
+* `--formula`:
+  Treat all named arguments as formulae.
+* `--cask`:
+  Treat all named arguments as casks.
 
 ### `command` *`cmd`*
 

manpages/brew.1

@@ -1274,8 +1274,16 @@ Print what would be done rather than doing it\.
 \fB\-\-message\fR
 Append \fImessage\fR to the default commit message\.
 .
-.SS "\fBcat\fR \fIformula\fR"
-Display the source of \fIformula\fR\.
+.SS "\fBcat\fR \fIformula\fR|\fIcask\fR"
+Display the source of a \fIformula\fR or \fIcask\fR\.
+.
+.TP
+\fB\-\-formula\fR
+Treat all named arguments as formulae\.
+.
+.TP
+\fB\-\-cask\fR
+Treat all named arguments as casks\.
 .
 .SS "\fBcommand\fR \fIcmd\fR"
 Display the path to the file being used when invoking \fBbrew\fR \fIcmd\fR\.