Class: FFI::AutoPointer

Inherits:
Pointer
  • Object
show all
Defined in:
lib/ffi/autopointer.rb,
ext/ffi_c/AutoPointer.c

Defined Under Namespace

Classes: CallableReleaser, DefaultReleaser, Releaser

Constant Summary

Constants inherited from Pointer

Pointer::NULL, Pointer::SIZE

Instance Method Summary collapse

Methods inherited from Pointer

#+, #==, #address, #inspect, #null?, #read_array_of_int, #read_array_of_long, #read_array_of_pointer, #read_array_of_type, #read_float, #read_int, #read_long, #read_long_long, #read_pointer, #read_string, #read_string_length, #read_string_to_null, size, #slice, #write_array_of_int, #write_array_of_long, #write_array_of_pointer, #write_array_of_type, #write_float, #write_int, #write_long, #write_long_long, #write_pointer, #write_string, #write_string_length

Constructor Details

#initialize(ptr, proc = nil, &block) ⇒ AutoPointer

call-seq:

AutoPointer.new(pointer, method)     => the passed Method will be invoked at GC time
AutoPointer.new(pointer, proc)       => the passed Proc will be invoked at GC time (SEE WARNING BELOW!)
AutoPointer.new(pointer) { |p| ... } => the passed block will be invoked at GC time (SEE WARNING BELOW!)
AutoPointer.new(pointer)             => the pointer's release() class method will be invoked at GC time

WARNING: passing a proc may cause your pointer to never be GC’d, unless you’re careful to avoid trapping a reference to the pointer in the proc. See the test specs for examples. WARNING: passing a block will cause your pointer to never be GC’d. This is bad.

Please note that the safest, and therefore preferred, calling idiom is to pass a Method as the second parameter. Example usage:

class PointerHelper
  def self.release(pointer)
    ...
  end
end

p = AutoPointer.new(other_pointer, PointerHelper.method(:release))

The above code will cause PointerHelper#release to be invoked at GC time.

The last calling idiom (only one parameter) is generally only going to be useful if you subclass AutoPointer, and override release(), which by default does nothing.

Raises:

  • (TypeError) 


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# File 'lib/ffi/autopointer.rb', line 59

def initialize(ptr, proc=nil, &block)
  raise TypeError, "Invalid pointer" if ptr.nil? || !ptr.kind_of?(Pointer) \
    || ptr.kind_of?(MemoryPointer) || ptr.kind_of?(AutoPointer)

  @releaser = if proc
                raise RuntimeError.new("proc must be callable") unless proc.respond_to?(:call)
                CallableReleaser.new(ptr, proc)

              else
                raise RuntimeError.new("no release method defined") unless self.class.respond_to?(:release)
                DefaultReleaser.new(ptr, self.class)
              end

  self.parent = ptr
  ObjectSpace.define_finalizer(self, @releaser)
  self
end

Instance Method Details

#autorelease=(autorelease) ⇒ Object 



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# File 'lib/ffi/autopointer.rb', line 81

def autorelease=(autorelease)
  @releaser.autorelease=(autorelease)
end

#free ⇒ Object 



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# File 'lib/ffi/autopointer.rb', line 77

def free
  @releaser.free
end