Re: Most awesome string metatable hack
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- Subject: Re: Most awesome string metatable hack
- From: steve donovan <steve.j.donovan@...>
- Date: Sat, 1 Feb 2014 09:41:17 +0200
On Fri, Jan 31, 2014 at 7:34 PM, Rena <hyperhacker@gmail.com> wrote:
> Functions also have metatables, which can be interesting:
I think Andrew is right - everyone who dives deeply enough in Lua goes
through a phase of fascination with overriding global metatables.
E.g. this function composition (plus using ^ for partial application)
appeared in an early version of Microlight.
In Penlight there's an option to overload behaviour of functions so
they have iterator methods:
http://stevedonovan.github.io/Penlight/api/topics/07-functional.md.html#Sequences
> seq.import()
> ('one two three'):gfind('%a+'):printall(',')
one,two,three,
(_Sequence_ of course is a word which now has a defined meaning in Lua
(basically, arrays) so pl.seq needs a terminological update.)
TFM observes that such tricks tend to lead to rather confusing errors:
"But there is a price to pay for this convenience. Every function is
affected, so that any function can be used, appropriate or not:
> math.sin:printall()
..seq.lua:287: bad argument #1 to '(for generator)' (number expected, got nil)
"