Ideal way to separate GUI and logic?

Chris Angelico rosuav at
Tue Jul 16 05:18:56 CEST 2013

On Tue, Jul 16, 2013 at 10:25 AM,  <fronagzen at> wrote:
> Again, thanks for all the responses. I'm curious, though, what exactly is the rationale for making functions so small? (I've heard that the function calling of Python has relatively high overhead?)

A function should be as long as it needs to be - neither longer nor
shorter. If you can name a function appropriately, and it's doing
exactly what its name suggests, it's the right length. This generally
produces short functions rather than long ones, but if the right
length for a function exceeds some arbitrary limit, let the function
be longer. For instance, I have a single function that's a bit over a
page in length, because it's one big switch block (this isn't in
Python, obviously), doing one thing fairly cleanly. Larger than that
would have to be called code smell, but there's certainly nothing
wrong with having the odd function here or there that's over Steven's
dozen-line estimate. There'll also be plenty of really short functions
- even one-liners.

The largest single function in any of my code, I think, is a gigantic
double-nested switch block in PHP .In any decent language, that would
be divided up not just into functions but into files, but PHP has some
stupid restrictions on its include directive that make that
impractical. So syntactically it's one massive function, but logically
it's about seven or eight separate sub-blocks, and the code is laid
out in those blocks. It's just that the technical nesting level never
actually hits zero in between them :) Have to confess, though, I've
had some fairly large functions in C++ (not as big as the
aforementioned, but still fairly large - what's the next one down from
gigantic, megantic? [1] would suggest so), which in some cases could
be split if I felt like putting in the time to do it.



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