Any form of IO is a side-effect, regardless of where you do it.

In an imperative language, 'functions' (procdures that return values if you prefer) are the major mechanism of code structuring. When I do IO to a database, I call a function (or method (same difference). When I read or write to a file, I call a function. When I read or write to a socket udp/tcp/http/ftp/telnet/et al, it is all done with functions and all of those functions that do IO have side-effects. f(a) + g(b) * h(c)

f(a) retrieves the range from the radar.

g(b) retrieves a correction factor from the wind speed indicator.

h(c) gets a scalar from a lookup table in memory. keyed upon the type of shell (HE, tracer, AP) that will load next from the belt.

The final result is used to adjust the elevation of the barrel in real time.

How do you avoid the side effects?

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
Lingua non convalesco, consenesco et abolesco.
Rule 1 has a caveat! -- Who broke the cabal?

In reply to Re^35: Side-effects are bad form [was: Why is the execution order...] by BrowserUk
in thread Why is the execution order of subexpressions undefined? by BrowserUk

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