This method is deprecated or moved on the latest stable version.
The last existing version (v1_9_3_392) is shown here.
format()
public
Lazy accessor for the installer’s Gem::Format instance.
# File lib/rubygems/installer.rb, line 117
def format
begin
@format ||= Gem::Format.from_file_by_path gem, @security_policy
rescue Gem::Package::FormatError
raise Gem::InstallError, "invalid gem format for #{gem}"
end
end