Re: lhs and rhs in table.sort

[iain morland <iain@...>]

Thank you Oliver; you are quite right about the function requiring an array.

I read the description of table.sort in PiL but am still unsure over “lhs" and “rhs". I couldn’t see those mentioned anywhere (in the whole book - unless Robert can please correct me!). How would a person know to use myArray[lhs] < myArray[rhs] in the first place? Are there other terms that might be used in place of “lhs” and “rhs” to do other things with the array? I feel that I am missing a crucial piece of understanding about this.

Regards
iain


> 
> Hi,
> 
> table.sort is described in chapter 20.2 of Programming in Lua. The 
> optional function argument is being called with two elements of the 
> table to be sorted and has to return true if the first of its arguments 
> shall come first in the sorted table.
> 
> Note that the function is actually only defined for an array, which is a 
> table with subsequent numbers as indices.
> 
> --
> Oliver
> 
> Am 24.08.2015 um 16:54 schrieb iain morland:
>> Greetings all,
>> 
>> I am researching the different compare functions that are available for use with the table.sort function.
>> 
>> After some searching online, I was able to use the following as the second argument in table.sort:
>> 
>> function(lhs,rhs) return myTable[lhs] < myTable[rhs] end
>> 
>> In turn, I used this to sort another table of the same size like so:
>> 
>> table.sort(otherTable,function(lhs,rhs) return myTable[lhs] < myTable[rhs] end)
>> 
>> However I couldn’t find reference to the use of "lhs" or “rhs" in the Lua documentation, and feel frustrated that I don’t fully understand what’s happening in the above code.
>> 
>> So I have two questions:
>> 
>> 1. Could anyone explain (or direct me to an explanation of) the different compare functions that can be used with table.sort?
>> 
>> 2. Are there any documented examples of how these functions work when sorting one table by the result of sorting another table?
>> 
>> Thanks in advance
>> iain
>