Re: Most awesome string metatable hack
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- Subject: Re: Most awesome string metatable hack
- From: Dirk Laurie <dirk.laurie@...>
- Date: 2014年1月31日 17:25:24 +0200
2014年01月31日 Andrew Starks <andrew.starks@trms.com>:
> [1] I wonder if discovering that there is a string metatable and that you
> can play with it is a common rite of passage amongst people who journey
> through lua...
I know of at least one more ...
About a year ago, John Hind and I were playing with an extended version
of the table library.
<https://github.com/dlaurie/xtable>
It contains a modified version of table.concat that applies tostring() to its
arguments instead of checking that they are numbers or strings.
Among the applications, we had:
Universal string concatenation
------------------------------
Define a metamethod for string concatenation as follows:
~~~
universal = function(a,b) return tostring(a)..tostring(b) end
getmetatable"".__concat = universal
~~~
This concatenates anything provided that the separator is a string.
A simple example is included in `test-xtable.lua`.
The universal concatenator is extremely powerful and it is a good
idea to detach it from string `__concat` when not in immediate use.
I was much more in love with this idea than John was, and eventually
`test-xtable.lua` did not make it to GitHub.