Question about build dependencies

[Ryan Schmidt]

On May 28, 2008, at 22:38, Tabitha McNerney wrote:

> I have what might seem to be a dumb question. I noticed today that  
> the MacPort named "libiconv" version 1.12 has a build dependency on  
> another port named gperf, specifically:
>
> $ port deps libiconv
> libiconv has build dependencies on:
> 	gperf
>
> What I find very interesting about this situation, however, is that  
> on my MacPorts system I have not consciously built / installed the  
> gperf port. But I have successfully built and installed the  
> libiconv port. Therefore, I am wondering, how is it possible that  
> the libiconv port was able to build and install without the gperf  
> port dependency having first been built?

Apparently libiconv requires gperf. I don't know anything about this;  
that's the way the port was when I inherited it.

The dependency is declared like this:

depends_build \
         bin:gperf:gperf

That means if a binary (the "bin" part) called "gperf" (the first  
"gperf" part) does not exist on the computer, then install the gperf  
port (the 2nd "gperf" part).

On my Tiger system, a gperf binary is provided by Mac OS X in /usr/ 
bin/gperf so the gperf port does not need to be installed.

Usually ports depend on other ports only. In this case, the previous  
maintainer of libiconv must've thought the gperf provided by Mac OS X  
was sufficient. I don't even know what gperf does.