Re: override and +=

[Greg Chicares]

On 2008-02-20 00:58Z, Michael Morrell wrote:
> I'm using gmake 3.81.  I read the manual about override and +=, but I
> guess
> I didn't understand it.  With the following Makefile:
> 
> =============================
> override F := "a b c"
> F += d
> 
> all:
>         @echo $F
> ==============================
> 
> I expected the "override" to have no effect unless I defined F on the
> command line.  Here's what I see:

This line
  override F := "a b c"
prevails     *even if* you set F on the command line,
rather than  *only if* you set F on the command line.

> % make
> a b c
> % make F="hello"
> a b c
> 
> In neither case, is the += doing anything.  Can someone explain this?

Write 'override' again:
  override F += d