Lua: functions and user input?

Question

I am trying to do a simple program in lua that aims to return a string with certain values based on the user input, however I am having issues scripting this.

For example, if I compile

person1 = {
name = "bob" ,
age = 70 ,
hair = "black" ,
};
person2 = {
name = "dan",
age = 40 ,
hair = "blonde" , 
};
describe = function(parent)
print ( "hello " .. parent.name .. " your are " .. parent.age .. " years old
and your hair color is " .. parent.hair )
end
print ("who are you") ;
answer = io.read ();
describe (answer)

I would expect that if I wrote person1 as the input the script would return a string that reads:

hello bob you are 70 years old and your hair color is black

However it instead returns an error.

The question is, what can I do to fix this? What is the right way to use user input in Lua?

You should indent your code, it makes it easier to read for us. — pschulz
– pschulz, Commented Aug 7, 2016 at 8:35

Jakuje · Accepted Answer · 2016-08-07 06:23:12Z

1

You would have to pass the object to the function, not the name. Or search for the object in the global scope:

person1 = {
    name = "bob" ,
    age = 70 ,
    hair = "black" ,
};
person2 = {
    name = "dan",
    age = 40 ,
    hair = "blonde" , 
};
describe = function(parent)
    parent = _G[parent]
    print ( "hello " .. parent.name .. " your are " .. parent.age .. " years old and your hair color is " .. parent.hair )
end
print ("who are you") ;
answer = io.read ();
describe (answer)

Working example: http://ideone.com/UJxnpx

answered Aug 7, 2016 at 6:23

Jakuje

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4 Comments

Hecedu Over a year ago

sorry, but, what does _G do?

Jakuje Over a year ago

It is the global scope, where all the global variables are stored. Check the manual for basic functions.

FareakyGnome Over a year ago

Forget about _G[parent] crap. Use something like this: local data={bob={age=70,hair="black"},dan={age=40,hair="blonde"}; parent = data[parent] or {age=-1,hair=-1}. Access to global variables based on user input - its vulnerability.

Jakuje Over a year ago

Yes, this is more clean solution.

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