Access one variable directly when more than one are returned

totebo

When a function returns more than one variable:

function getVars() return var_a, var_b end

Is it possible to get only var_b directly when calling the function? Something like:

print( getVars()[2] )

To avoid:

local var_1, var_2 = getVars() print( var_2 )

Nic

totebo

Rewrote this question since it's more of a straight-up Lua question rather than Box2D specifically.

keszegh

local _, var_2 = getVars()

should work, see here:
http://stackoverflow.com/questions/3165845/how-can-i-ignore-first-results-from-a-function-in-lua

totebo

Thanks @keszegh.

To me it seems like the cleanest solution is to add a method that returns just one specific value;

function getVarB() return var_b end

My use case is getting the Y position of a Body in Box2D directly. I'm now extending the Body class with Body:getY().

Happy days.

tkhnoman

function getVars() return {var_a, var_b} end   print( getVars()[2] )   local var_1, var_2 = unpack( getVars() )

hgy29

What about something like that:

print(table.pack(getVars())[2])

Not that this is probably not efficient at all, but seems pretty much what you were looking for...

totebo

Hey @hgy29, that would do it! You're right, doesn't feel like the "right" way of doing it.

@tkhnoman, that also works, but not without changing the Box2D interface unfortunately.