I'm not sure if you're seriously questioning, or if you're trying to win an argument. i'm going to go with the notion that you're genuinely curious. I worked

I'm not sure if you're seriously questioning, or if you're trying to win an argument. i'm going to go with the notion that you're genuinely curious. I worked on a project with grids, an editable table like an excel sheet. Each grid, row, column, and cell could be styled. Font as Arial, Comic Sans ...; Color as rgb; padding top, left...; background color as rgb; Alignment as left, right or justified; format as freeform string, integer, float money or regex; decimal separator as . or , ; thousands separator as . or ,; and a whole bunch more. The first cut just naively associated a style struct as part of each cell's data. Several customers complained that grids were very slow to start up, a few complained that they were running out of memory. They were using very large datasets for the grid, and the naive implementation wasted a lot of time on initialization, and a lot of memory on duplicate representation of style. In retrospect it was a stupid mistake to make. We'd only tested against small amounts of data on relatively fast machines. Customers were using millions of rows. The solution we went with was the aforementioned pattern. it saved a ton of memory and a ton of time avoiding all of that initialization. There were a few rounds dealing with smart lookup of style based on cell, row, column, and overall table. My c++ is rusty, but i'm a little baffled by your confusion. Iterating over data structures in a uniform was was kind of a big deal back in the day. IIRC, implementing preorder, inorder and postorder iterators for a binary tree was homework. Have iterators fallen out of fashion? I don't have a peer reviewed paper paper indicating flyweight is helpful. I don't have a peer reviewed paper saying multiplication is better than looping over adding m to itself n times. It's just better. Some of them are mostly stupid, ala singleton. Of course even stupid singleton is a nice place to stick environment variables, because they are globals. I never thought decorator was all that great. I really like composite, but i like tree representations that i can recurse over. If i had a scale, where you could place code on one side, and a design pattern on the other side, and it would balance if adding the design pattern was worth it, i would give it to you. To my knowledge, no such thing exists. If you have questions, i'll try to answer. here or jfoutz at gmail.