On Thursday, June 16, 2016 at 5:48:48 PM UTC+12, Rustom Mody wrote: > On Thursday, June 16, 2016 at 8:25:10 AM UTC+5:30, Lawrence D’Oliveiro wrote: > So here is the formal definition I remember from decades ago: > > A structured flow-graph is one that has a single point of entry and exit. > And is recursively made from smaller structured flow graphs > With a finite set of 'graph combinators' > > A structured program is one who's flow graph is structured > > As I said I dont find this definition very useful since > break is unstructured as is return, yield and much else.
On the contrary, it fits in nicely. Imagine trying to represent your code as a Nassi-Shneiderman diagram. This consists (recursively) of nested and/or concatenated sub-diagrams. Each piece has one entry point at the top, and one exit point at the bottom. In particular, it is *not possible* to express a goto that jumps from one arbitrary point to another--everything must strictly nest. For example, a loop is entered at the top, and exited at the bottom. A “break” in the loop can cut it short, but it cannot violate this rule. Even my C code follows this nesting principle, because it is goto-free. -- https://mail.python.org/mailman/listinfo/python-list
