Re^2: Code clarification - use of map and $$_

[Anonymous Monk]

Thanks for that. Why exactly would dereferencing be used here? Why not direct access to the variable?

[davido]

Because the list returned by @{$r{$k}} is a list of array references. On each iteration of the map loop one element is passed in from the array, @{$r{$k}}, to $_. That element is a reference to an array. Thus, to act upon its contents, you dereference it.

[LanX]

> Why exactly would dereferencing be used here? Why not direct access to the variable?

without digging too deep into this code ...

map can only iterate over scalars.

I.e. like a list of $array_refs, if you want to address different arrays ...

> Why not direct access to the variable?

if you mean something like @array as the "direct" variable, you CAN'T do something like

map { $_[0]++ } (@a,@b,@c)

to increment the first element of each array.

The real problem with that code is the laziness of the author to use a clear style.

[Corion]

I don't know. Maybe ask the original author of the script.