I do not understand this error, help me !

This is my prog. :

print("Cash register 1")
print("Owner : leonekmi")
print("Scan your card")
reader = peripheral.wrap("right")
reader.setInsertCardLight(true)
local event, data = os.pullEvent()
if data == "0000leonekmi" then
print("Cash Register ready")
mon = peripheral.wrap("top")
read = peripheral.wrap("left")
reader.setInsertCardLight(false)
else
print("Invalid card")
reader.setInsertCardLight(false)
error("Invalid card")
end
local value = read() – My program crash at this line.+

Help me !
Thanks !

You redifined read:

read = peripheral.wrap("left")

You can't call a peripheral.

For future referance:
Post the full error
put your code between

 -thecode- 

(without the spaces)

I write in my prog.

value1 = read()

And my program crash

prog:1: attempt to call table

My prog has crashed to the same error

print("Cash register 1")
print("Owner : leonekmi")
print("Scan your card")
reader = peripheral.wrap("right")
reader.setInsertCardLight(true)
event, data = os.pullEvent()
if data == "0000leonekmi" then
  print("Cash Register ready")
  mon = peripheral.wrap("top")
  reader2 = peripheral.wrap("left")
  reader.setInsertCardLight(false)
  else
  print("Invalid card")
  reader.setInsertCardLight(false)
  error("Invalid card")
end

print("Amount :")
value = read()

And error is

program:22: attempt to call table

It is a good idea when requesting help on these forums to post your code so that we can assist you faster and easier.

The error you're getting means that you have a variable (more specifically a table) defined somewhere called read which is overriding ComputerCraft's read function. You cannot have multiple things named the same.

That program doesn't even have 22 lines, so it would be impossible for it to throw that error.

Merged threads, please stick to one thread per program/problem, it allows us to easier keep track of your problem and give you the best advice possible.

leonek68, on 21 August 2014 - 03:05 PM said:

My prog has crashed to the same error

print("Cash register 1")
print("Owner : leonekmi")
print("Scan your card")
reader = peripheral.wrap("right")
reader.setInsertCardLight(true)
event, data = os.pullEvent()
if data == "0000leonekmi" then
  print("Cash Register ready")
  mon = peripheral.wrap("top")
  reader2 = peripheral.wrap("left")
  reader.setInsertCardLight(false)
  else
  print("Invalid card")
  reader.setInsertCardLight(false)
  error("Invalid card")
end

print("Amount :")
value = read()

And error is

program:22: attempt to call table

I bet you need to restart the computer. Since you used global variables (not a good idea), the global "read" function was overwritten when you ran your first code. Either shutdown the computer you are testing on or make a new one.

KingofGamesYami, on 21 August 2014 - 03:49 PM said:

leonek68, on 21 August 2014 - 03:05 PM said:

My prog has crashed to the same error

…

And error is

program:22: attempt to call table

I bet you need to restart the computer. Since you used global variables (not a good idea), the global "read" function was overwritten when you ran your first code. Either shutdown the computer you are testing on or make a new one.

KingofGamesYami makes a good point - you *should* localize your varaibles. However, I don't see where 'read' is being overwritten in the posted code (it was being overwritten in the original code). I see 'reader' as a variable, but I don't see 'read' being referenced anywhere. Also, that code is only 19 lines long so, as Lyqyd said, getting the error you reported on that code is impossible. Please post the entire code.

Dog, on 21 August 2014 - 07:34 PM said:

KingofGamesYami makes a good point - you *should* localize your varaibles. However, I don't see where 'read' is being overwritten in the posted code (it was being overwritten in the original code). I see 'reader' as a variable, but I don't see 'read' being referenced anywhere. Also, that code is only 19 lines long so, as Lyqyd said, getting the error you reported on that code is impossible. Please post the entire code.

Dog, the original code was running on the same computer, on the same LuaVM, with the same global space. It can be polluted once and affect all the programs you are trying to run. That's why "os.pullEvent = os.pullEventRaw" trick affects the whole computer. After restart CraftOS brings all of the functions back.

0099, on 22 August 2014 - 01:45 PM said:

Dog, on 21 August 2014 - 07:34 PM said:

KingofGamesYami makes a good point - you *should* localize your varaibles. However, I don't see where 'read' is being overwritten in the posted code (it was being overwritten in the original code). I see 'reader' as a variable, but I don't see 'read' being referenced anywhere. Also, that code is only 19 lines long so, as Lyqyd said, getting the error you reported on that code is impossible. Please post the entire code.

Dog, the original code was running on the same computer, on the same LuaVM, with the same global space. It can be polluted once and affect all the programs you are trying to run. That's why "os.pullEvent = os.pullEventRaw" trick affects the whole computer. After restart CraftOS brings all of the functions back.

0099 - thanks for the explanation, but I'm clear on the difference between local and global space. What I missed was the use of 'read' in the original post - now I see where things went awry.