[SOLVED] Can a function be extended in Bash?

Issue

If I define a function in a file, say test1.sh:

#!/bin/bash

foo() {
    echo "foo"
}

And in a second, test2.sh, I try to redefine foo:

#!/bin/bash

source /path/to/test1.sh    
...
foo() {
    ...
    echo "bar"
}
foo

Is there a way to change test2.sh to produce:

foo
bar

I know it is possible to do with Bash built-ins using command, but I want to know if it is possible to extend a user function?

Solution

I'm not sure I see the need to do something like this. You can use functions inside of functions, so why reuse the name when you can just call the original sourced function in a newly created function like this:

AirBoxOmega:stack d$ cat source.file
#!/usr/local/bin/bash

foo() {
    echo "foo"
}
AirBoxOmega:stack d$ cat subfoo.sh
#!/usr/local/bin/bash


source /Users/d/stack/source.file
sub_foo() {
  foo
  echo "bar"
}

sub_foo
AirBoxOmega:stack d$ ./subfoo.sh
foo
bar

Of course if you REALLY have your heart set on modifying, you could source your function inside the new function, call it, and then do something esle after, like this:

AirBoxOmega:stack d$ cat source.file
#!/usr/local/bin/bash

foo() {
    echo "foo"
}
AirBoxOmega:stack d$ cat modify.sh
#!/usr/local/bin/bash


foo() {
  source /Users/d/stack/source.file
  foo
  echo "bar"
}

foo
AirBoxOmega:stack d$ ./modify.sh
foo
bar

Answered By - drldcsta

Answer Checked By - Willingham (WPSolving Volunteer)