documentation of pextlib1.0 commands

[Rainer Müller]

Ryan Schmidt wrote:
> On Jun 11, 2008, at 03:45, Caspar Florian Ebeling wrote:
> 
>> Is there documentation of the mp-specific commands
>> somewhere, that I overlooked? Things like "system"?
>> I found the definition in macports/base/src/pextlib1.0/Pextlib.c,
>> eventually, but it is still a bit uncomfortable. In this case e.g.
>> I wanted to see if it returns output from stdout and
>> exit code.

I think this should be documented in this section in the guide, but it 
is not.
<http://guide.macports.org/#reference.tcl-extensions>

What is missing besides 'system'?

> I'm not aware of documentation. I generally just look at other ports  
> or parts of base that do what I want and copy it.

Looking at other Portfiles is always possible, but it is not a 
replacement for documentation.

> If you want to get output from the command, use exec. For example,  
> see the nspr port which does:
> 
>          set mylibs [exec ${destroot}${prefix}/bin/nspr-config --libs]
> 
> To catch errors you can use catch, like src/port1.0/portutil.tcl does  
> in MacPorts base:
> 
>          if {[catch {exec cp $tmpfile $file} error]} {
>              global errorInfo
>              ui_debug "$errorInfo"
>              ui_error "reinplace: $error"
>              file delete "$tmpfile"
>              return -code error "reinplace copy failed"
>          }

But exec and catch are usual Tcl stuff, which are documented in 'man n 
exec' and 'man n catch'.

MacPorts adds its own commands for use in Portfiles with Pextlib and 
they should be documented.

Rainer