Reference Manual
Release Notes
PDF
Top

Kernel
Reference Manual
Version 2.13.5

Expand All
Contract All

Table of Contents

# error_handler

### MODULE

error_handler

### MODULE SUMMARY

Default System Error Handler

### DESCRIPTION

The error handler module defines what happens when certain types of errors occur.

### EXPORTS

undefined_function(Module, Function, Args) -> term()

Types:

Module = Function = atom()
Args = [term()]
A (possibly empty) list of arguments Arg1,..,ArgN

This function is evaluated if a call is made to Module:Function(Arg1,.., ArgN) and Module:Function/N is undefined. Note that undefined_function/3 is evaluated inside the process making the original call.

If Module is interpreted, the interpreter is invoked and the return value of the interpreted Function(Arg1,.., ArgN) call is returned.

Otherwise, it returns, if possible, the value of apply(Module, Function, Args) after an attempt has been made to autoload Module. If this is not possible, the call to Module:Function(Arg1,.., ArgN) fails with exit reason undef.

undefined_lambda(Module, Fun, Args) -> term()

Types:

Module = Function = atom()
Args = [term()]
A (possibly empty) list of arguments Arg1,..,ArgN

This function is evaluated if a call is made to Fun(Arg1,.., ArgN) when the module defining the fun is not loaded. The function is evaluated inside the process making the original call.

If Module is interpreted, the interpreter is invoked and the return value of the interpreted Fun(Arg1,.., ArgN) call is returned.

Otherwise, it returns, if possible, the value of apply(Fun, Args) after an attempt has been made to autoload Module. If this is not possible, the call fails with exit reason undef.

### Notes

The code in error_handler is complex and should not be changed without fully understanding the interaction between the error handler, the init process of the code server, and the I/O mechanism of the code.

Changes in the code which may seem small can cause a deadlock as unforeseen consequences may occur. The use of input is dangerous in this type of code.