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0 pointsbigtunacan11y ago0 comments

Symbols are not a syntactic issue. They are an optimization issue. They do not have the creation overhead of objects and they exist across the application in memory without the lookup overhead of a constant (PHP's closest cousin to a symbol).

Lisp, Erlang, and Prolog (sure some other languages I've missed) have direct equivalents to Ruby symbols; they are sometimes referred to as symbols other times as atoms.

Saying they are a trivial syntactic issue just means you don't understand what symbols are.

0 comments

lmz11y ago

It's a bit silly to worry about the overhead of strings over symbols when the PHP environment itself is not persistent across requests.

bigtunacanOP11y ago

That seems to be missing the whole point of symbols/atoms. They are uniquely identified with an O(1) lookup time and persist in memory after the initial creation. Symbols persist across multiple requests; this is a big part of why they are so beneficial.

girvo11y ago

I'm not disagreeing with you, but

> Symbols persist across multiple requests; this is a big part of why they are so beneficial.

That is still not really useful, PHP throws the entire execution context away after the request has finished. There is no sharing nor anything to persist unless you're doing so with an external data-store.

2 more replies

pestaa11y ago

It adds up. One request may produce millions of such strings. Ruby and especially RoR without cheap symbol lookups would be as fast as a dead fish.

coldtea11y ago

You're not supposed to have "millions of symbols" in Ruby (or LISP for that matter) either.

I mean, you technically could, but it's not what they are used for.

nikic11y ago

Ruby only needs symbols because it made the questionable choice of using mutable strings with by-object semantics. PHP does not have this problem. It will automatically intern literal strings, thus giving you the performance and memory usage benefits of symbols, but without the crutch of requiring a special syntax for them.

Daishiman11y ago

I think that special symbol syntax is nice, since it has additional semantic meaning in the form of "this data type here is used to represent a flag, not a piece of text".

Granted, Ruby's use of symbols is not as pretty as other languages...

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