LuaFix2 - Example - elseifs
Go back to Luafix2
Consider the following code:
local n = math.random()
if n > .25 and n < .5 then
print(n - .25)
print("in middle")
elseif n >= .5 and n < .75 then
print(n + .25)
print("in middle")
end
The print("in middle") is the same in two places; if I wanted to
change it, I would have to change it in several places. If I was replacing it
with a loop, then I would have a loop twice.
This means we should pull this code to after the if so that the
same one is used by both. A simple if has to be added to make it
only happen when one of the previous branches happened. It is easy to
do this in this case:
local n = math.random()
if n > .25 and n < .5 then
print(n - .25)
elseif n >= .5 and n < .75 then
print(n + .25)
end
if n > .25 and n < .75 then
print("in middle")
end
Let's say we're making a simple game and there are several materials: Stone,
Grass, Glass, and Dirt — there are no other materials. Thus the following
does not require an else clause.
if material == "Stone" then
getStone();
wait(1)
print("You got Stone")
elseif material == "Grass" then
getGrass();
wait(1)
print("You got Grass")
elseif material == "Glass" then
getGlass();
wait(1)
print("You got Glass")
elseif material == "Dirt" then
getDirt();
wait(1)
print("You got Dirt")
end
In this case, we know we are always going to get that message printed.
The last statement is a little different each time. Let's change it a little.
The following does the same thing:
if material == "Stone" then
getStone()
wait(1)
print("You got " .. material) -- Stone
elseif material == "Grass" then
getGrass()
wait(1)
print("You got " .. material) -- Grass
elseif material == "Glass" then
getGlass()
wait(1)
print("You got " .. material) -- Glass
elseif material == "Dirt" then
getDirt()
wait(1)
print("You got " .. material) -- Dirt
end
Now each line ends with the same thing. We know that at least one
will happen, so we can just move the
print("You got " .. material) after the if:
if material == "Stone" then
getStone()
elseif material == "Grass" then
getGrass()
elseif material == "Glass" then
getGlass()
elseif material == "Dirt" then
getDirt()
end
wait(1)
print("You got " .. material) -- Whatever
You could probably take this further and reduce the likely reuse between the
getStone(), getGrass(), etc.