Epicycles

Post #156,776 by tablizer 5/24/04 10:51:41 PM Reply	Epicycles The final leap of logic is that you are then free to distribute that class with its IF statements to ONE customer But what if other customers need the same IF? Copy-and-paste? That is what we were trying to avoid to begin with. This is one of the central tenets of OOP: "separate the things that change from the things that stay the same. Task-ness tends to stay the same more than noun taxonomies or noun-based grouping. By the way, rather than say "if customer==b then..." better indirection is "if customer.hasFeatureX then...". However, one should wait until about 3 customers use that feature before making it a column. ________________ oop.ismad.com
Post #156,787 by admin 5/25/04 12:05:15 AM Reply	Re: Epicycles By the way, rather than say "if customer==b then..." better indirection is "if customer.hasFeatureX then...". However, one should wait until about 3 customers use that feature before making it a column. Better is a relative term. By adding a new feature (or when changing it to a column from an IF) you've just made a branchable change in a monolithic file. Have A Nice Day, the build manager will be around to see you later today. Whereas adding a new decryption algorithm/parser/whatever in my setup only affects that bit and that bit only. Regards, -scott anderson "Welcome to Rivendell, Mr. Anderson..."
Post #156,844 by FuManChu 5/25/04 11:13:30 AM Reply	Once more with feeling I wrote: > The final leap of logic is that you are then free to > distribute that class with its IF statements to ONE customer and you replied: > But what if other customers need the same IF? Then, again, you are free (not forced) to distribute to them. Under your scheme, there is no freedom--you force it upon all, since there is no separation between what changes and what stays the same. > Copy-and-paste? I think you're still thinking: customer = get_customer()\nif customer!id == 'a':\n [big block of code]\nelse if customer!id =='b':\n [same big block of code]\nelse if customer!id =='c':\n [another big block of code]\n... That's not composition. Composition says: customer = get_customer()\ncustomer.handler.do() The only "copy-and-paste" might be in a config file: one atom which reads `"handler = customHandler"` instead of `"handler = default"` (or even better, no line at all for the default). Verstehen wir uns? "There's a set of rules that anything that was in the world when you were born is normal and natural. Anything invented between when you were 15 and 35 is new and revolutionary and exciting, and you'll probably get a career in it. Anything invented after you're 35 is against the natural order of things." Douglas Adams

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