How to define the "=" equals sign as a Bash alias?

Question

I want to define the = equals sign as a Bash alias but Bash does not allow any of the following definitions:

alias =='echo foo'
alias \=='echo foo'
alias -- =='echo foo'
alias -- \=='echo foo'

Does someone know a notation that works?

Answer 1

This is one of the reserved special chars, used for assignment and test and you cannot use it for alias. More info: http://tldp.org/LDP/abs/html/varassignment.html#EQREF

Answer 2

Use a function:

=() { echo "foo"; }