Executes a function in a protected mode.

Syntax

bStatus, result = pcall(f, arg1, ....)

Arguments

Name

Description

f

A function.

arg

A variable passed as an argument to the function 'f', equivalent to f(arg1).

Outputs

Name

Description

bStatus

A Boolean (true if the call succeeds, false if there is an error).

result

The result of the call.  If bStatus is false, a string with the error message.

Example

Syntax

function foo(a,b)

  return a + b

end

// executes foo function with 3 and 4 as input argument

s1, r1 = pcall(foo, 3, 4)

print(s1);

print(r1);

// executes foo function with 'a' and [3 4] as input argument

// foo generates an error in this case catched by pcall

s2, r2 = pcall(foo, 'a', [3 4])

print(s2);

print(r2);

// example to execute a string if it is possible

b1, m1 = pcall(Eval,'aa = 3')

print(b1);

print(exist('aa'))

print(m1);

// zi does not exist. an error will be created and catched by pcall

b2, m2 = pcall(Eval,'aaa = zi + 3')

print(b2);

print(exist('aaa'))

print(m2);

Comments

The 'pcall' function can be used with 'Eval' to execute a string and detect an error.

See Also:

Eval