toboolean function

[Schwender.exe]

edit #4
- made it easier to add more 'true' strings
- made it actually work this time
(thanks to grumpy and zorg for help fixing it, and hi reddit!)

Code: Select all

local tobool_True = {"1","true","t","yes","y"}
function tobool(str)
  if type(str) ~= "string" then str = tostring(str) end
  str = string.lower(str)
  for i=1,#tobool_True do
    if str == string.lower(tobool_True[i]) then
      return true
    end
  end
  return false
end

[zorg]

On the other hand, lua treats everything except false and nil as logically true, so a simple

Code: Select all

if x then
-- true
else
-- false
end

[grump]

Extremely robust... toboolean(true) returns nil though, which means true is false.

And are you sure that toboolean(1) should equal true, although toboolean("1") equals false? What about toboolean("broken code")?

[Schwender.exe]

Extremely robust... toboolean(true) returns nil though, which means true is false.

And are you sure that toboolean(1) should equal true, although toboolean("1") equals false? What about toboolean("broken code")?

going to re-write it, mb

[Schwender.exe]

On the other hand, lua treats everything except false and nil as logically true, so a simple

Code: Select all

if x then
-- true
else
-- false
end

yea, I re-wrote it, sorry!

[grump]

Code: Select all

function toboolean(str)
  str = tostring(str)
  if str == "1" or "true" or "t" then
    return true
  else
    return false
  end
end

Now it's even more broken. This code always returns true.

You probably want this:

Code: Select all

function tobool(val)
    if type(val) == "string" then
        return val == "true" or val == "t" or val == "1" -- return true for these values, false for all other strings
    end
    return val -- not a string, use default behavior
end

[Azhukar]

Code: Select all

boolean = not not myvariable

[grump]

Code: Select all

boolean = not not myvariable

That returns true for all strings. Not what OP wants.

[Azhukar]

That returns true for all strings. Not what OP wants.

The solution to that is to change what the OP wants since OP is wrong. If you're going to redefine what boolean means in the language you're using, you'll end up spending a lot more effort on nothing.

[grump]

The solution to that is to change what the OP wants since OP is wrong. If you're going to redefine what boolean means in the language you're using, you'll end up spending a lot more effort on nothing.

You need to enhance your calm. OP just wants to parse a string and convert some values to boolean. There is nothing inherently wrong with that. Maybe he wants to write a config file parser, who knows.