note adrianh <blockquote><em>I've studiously avoided the term "flyweight objects" as I have only ever seen it here and didn't really understand its meaning. I'll stick to "Inside-out" which only has meaning in perl terms as far as I am aware.</em></blockquote> <p>Fair enough, but [id://219525|other] [id://219561|people] [id://219968|have] - which makes me suspect it means something different in the perl and design pattern worlds.</p> <p>Which would be annoying. One of the main advantages of the design pattern movement for me is the development of a common vocabularly (finally, everybody knows what a singleton is :-). If it means something different in the perl world it would be useful to know.</p> <blockquote><em>With regard to the example you describe, that may have made some sense in the world of 8-bit chars as you only need a pool of 256 object, but in the world of UCS, it becomes excessive I think...</em></blockquote> <p>I don't really want to repeat everything in the chapter from the book, but basically...</p> <ul> <li>The context is a word processor, so "character" doesn't just mean the code, it might support methods like draw(), intersects(), etc. We're talking WYSIWYG layout support.</li> <li>I didn't mean to imply you had to create the whole pool of characters at once, you would create them as needed for a document and add them to the pool.</li> </ul> <p>As for practicality, the example was in the book was adapted from the Doc editor, produced using InterViews 3.0. Take a look at: <ul> <li>Paul R. Calder and Mark A Linton. Glyphs: Flyweight bjects for user interfaces. In ACM User Interface Software Technologies Conference, pages 92-101, Snowbird, UT, October 1990.</li> <li>Paul R. Calder and Mark A Linton. The object-oriented implementation of a document editor. In Object-Oriented Programming Systems, Languages and Applications Conference Proceedings, pages 154-165m Vancouver, British Columbia, Canada, October 1992. ACM Press.</li> </ul> <p>To quote from the [isbn://0-201-63361-2|Design Patterns] chapter on flyweights:</p> <blockquote> Doc uses glyph objects to represent each character in the document. The editor builds one Glyph instance for each character in a particular style (which defines its graphical attributes); hence a character's intrinsic state consists of the character code and its style information (an index into a style table). This means only position is extrinsic making Doc fast. </blockquote> <p>If you're interested in the details I'd recommend picking up a copy of [isbn://0-201-63361-2|Design Patterns] and giving the flyweight chapter a read.</p> 219924 220010