Module: FFI::DRY::StructHelper::ClassMethods

Defined in:
lib/ffi/dry.rb

Overview

Contains dsl_layout and some support methods that an ‘includee’ of DryStructHelper will have available as class methods.

Instance Method Summary collapse

Instance Method Details

#_class_meths_from_dsl_metadata(meta) ⇒ Object 



208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
 
# File 'lib/ffi/dry.rb', line 208

def _class_meths_from_dsl_metadata(meta)
  (@dsl_metadata = meta).each do |spec|
    name = spec[:name]
    ftype = spec[:type]
    if p=spec[:p_struct] and p.kind_of?(Class)
      define_field_accessor(:"#{name}") do
        p.new(self[name]) unless self[name].null?
      end
    else
      define_field_accessor(:"#{name}") { self[name] }
    end

    define_field_accessor(:"#{name}=") {|val| self[name]=val }
  end
end

#define_field_accessor(name, &block) ⇒ Object 



178
179
180
181
182
183
184
185
 
# File 'lib/ffi/dry.rb', line 178

def define_field_accessor name, &block
  if instance_methods.include?("#{name}")
    warn "WARNING: The name '#{name}' is in use for class #{self} "+
         "Skipping automatic method creation in dsl_layout block."
  else
    define_method name, &block
  end
end

#dsl_layout(&block) ⇒ Object

This passes a block to an instance of DSLStructLayoutBuilder, allowing for a more declarative syntax with additional metadata to be included.

dsl_layout() a replacement to layout() and stores the dsl_metadata gathered about structure members locally and automatically creates accessor methods for each field in the structure.

NOTE if a structure field name conflicts with another instance method already defined in the class, the relevant accessor method is not created and a warning is issued. This does not apply to methods defined after the dsl_layout block is called. In other words this does not affect the overriding of accessor methods in any way.



199
200
201
202
203
204
205
206
 
# File 'lib/ffi/dry.rb', line 199

def dsl_layout &block
  builder = DSLStructLayoutBuilder.new(self)
  builder.instance_eval(&block)
  @layout = self.layout(*(builder.__layout_args))
  @size = @layout.size
  _class_meths_from_dsl_metadata( builder.__metadata )
  return @layout
end

#dsl_metadata ⇒ Object

returns the structure metadata for this class based on the dsl_layout definitions



174
175
176
 
# File 'lib/ffi/dry.rb', line 174

def dsl_metadata
  @dsl_metadata
end