class YARD::Tags::MacroDirective
Defines a block of text to be expanded whenever the macro is called by name in subsequent docstrings. The macro data can be any arbitrary text data, be it regular documentation, meta-data tags or directives.
Defining a Macro¶ ↑
A macro must first be defined in order to be used. Note that a macro is also expanded upon definition if it defined on an object (the docstring of a method, class, module or constant object as opposed to a free standing comment). To define a macro, use the “new” or “attach” identifier in the types specifier list. A macro will also automatically be created if an indented macro data block is given, so the keywords are not strictly needed.
Anonymous Macros¶ ↑
In addition to standard named macros, macros can be defined anonymously if no name is given. In this case, they can not be re-used in future docstrings, but they will expand in the first definition. This is useful when needing to take advantage of the macro expansion variables (described below).
Using a Macro¶ ↑
To re-use a macro in another docstring after it is defined, simply use @!macro the_name
with no indented block of macro data. The resulting data will be expanded in place.
Attaching a Macro to a DSL Method¶ ↑
Macros can be defined to auto-expand on DSL-style class method calls. To define a macro to be auto expanded in this way, use the “attach” keyword in the type specifier list (“new” is implied).
Attached macros can also be attached directly on the class method declaration that provides the DSL method to its subclasses. The syntax in either case is the same.
Macro Expansion Variables¶ ↑
In the case of using macros on DSL-style method calls, a number of expansion variables can be used for interpolation inside of the macro data. The variables, similar in syntax to Ruby's global variables, are as follows:
-
$0 - the method name being called
-
$1, $2, $3, … - the Nth argument in the method call
-
$& - the full source line
The following example shows what the expansion variables might hold for a given DSL method call:
property :foo, :a, :b, :c, String # $0 => "property" # $1 => "foo" # $2 => "a" # $& => "property :foo, :a, :b, :c, String"
Ranges¶ ↑
Ranges are also acceptable with the syntax ${N-M}
. Negative values on either N or M are valid, and refer to indexes from the end of the list. Consider a DSL method that creates a method using the first argument with argument names following, ending with the return type of the method. This could be documented as:
# @!macro dsl_method # @!method $1(${2--2}) # @return [${-1}] the return value of $0 create_method_with_args :foo, :a, :b, :c, String
As described, the method is using the signature foo(a, b, c)
and the return type from the last argument, String
. When using ranges, tokens are joined with commas. Note that this includes using $0:
!!!plain $0-1 # => Interpolates to "create_method_with_args, foo"
If you want to separate them with spaces, use $1 $2 $3 $4 ...
. Note that if the token cannot be expanded, it will return the empty string (not an error), so it would be safe to list $1 $2 ... $10
, for example.
Escaping Interpolation¶ ↑
Interpolation can be escaped by prefixing the +$+ with +\+, like so:
# @!macro foo # I have \$2.00 USD.
@example Defining a simple macro
# @!macro [new] returnself # @return [self] returns itself
@example Using a simple macro in multiple docstrings
# Documentation for map # ... # @macro returnself def map; end # Documentation for filter # ... # @macro returnself def filter; end
@example Attaching a macro to a class method (for DSL usage)
class Resource # Defines a new property # @param [String] name the property name # @param [Class] type the property's type # @!macro [attach] property # @return [$2] the $1 property def self.property(name, type) end end class Post < Resource property :title, String property :view_count, Integer end
@example Attaching a macro directly to a DSL method
class Post < Resource # @!macro [attach] property # @return [$2] the $1 property property :title, String # Macro will expand on this definition too property :view_count, Integer end
@since 0.7.0
Public Instance Methods
# File lib/yard/tags/directives.rb, line 252 def call raise TagFormatError if tag.name.nil? && tag.text.to_s.empty? macro_data = find_or_create unless macro_data warn return end self.expanded_text = expand(macro_data) end
Private Instance Methods
# File lib/yard/tags/directives.rb, line 281 def anonymous? tag.name.nil? || tag.name.empty? end
# File lib/yard/tags/directives.rb, line 270 def attach? new? && # must have data or there is nothing to attach class_method? || # always attach to class methods (tag.types && tag.types.include?('attach')) end
# File lib/yard/tags/directives.rb, line 276 def class_method? object && object.is_a?(CodeObjects::MethodObject) && object.scope == :class end
# File lib/yard/tags/directives.rb, line 285 def expand(macro_data) return if attach? && class_method? return if !anonymous? && new? && (!handler || handler.statement.source.empty?) call_params = [] caller_method = nil full_source = '' if handler call_params = handler.call_params caller_method = handler.caller_method full_source = handler.statement.source end all_params = ([caller_method] + call_params).compact CodeObjects::MacroObject.expand(macro_data, all_params, full_source) end
# File lib/yard/tags/directives.rb, line 301 def find_or_create if new? || attach? if handler && attach? if object && object.is_a?(CodeObjects::NamespaceObject) log.warn "Attaching macros to non-methods is unsupported, ignoring: " \ "#{object.path} (#{handler.parser.file}:#{handler.statement.line})" obj = nil else obj = object ? object : P("#{handler.namespace}.#{handler.caller_method}") end else obj = nil end return tag.text || "" if anonymous? # anonymous macro macro = CodeObjects::MacroObject.create(tag.name, tag.text, obj) else macro = CodeObjects::MacroObject.find(tag.name) end macro ? macro.macro_data : nil end
# File lib/yard/tags/directives.rb, line 265 def new? (tag.types && tag.types.include?('new')) || (tag.text && !tag.text.strip.empty?) end
# File lib/yard/tags/directives.rb, line 325 def warn if object && handler log.warn "Invalid/missing macro name for " \ "#{object.path} (#{handler.parser.file}:#{handler.statement.line})" end end