How to parse a Portfile?

[Joshua Root]

On 1/12/2023 11:27, Frank Stock wrote:
> Section 6.4.1 has an interesting bullet…
> "Ports API - API for Portfile parsing and execution”
> 
> I would like to extract information from a Portfile such as, version, license, add_users, startupitem, post-destroot, etc. for analysis/processing in a Node.js app.
> Thought I might be able to use a Tcl Interpreter such as npm tcl or npm tcl-js to load from base/src/port1.0/ and obtain what I want using mportinfo.
> 
> But I confess, being a newbie to Tcl as well as MacPorts internals, after a day of “grep”, I still haven’t figured out how (or even if its possible) to load the API into an interpreter outside MacPorts?
> 
> Are there better ways to accomplish my goal of extracting Portfile info?
> Wish I could just use “port info acme”, but add_users and post-destroot are some of the required pieces of info I need.

Portfiles can contain arbitrary Tcl code and rely heavily on the code in 
MacPorts base, so no, there's not really any way to correctly evaluate 
them without using the macports API. There are quite a few examples in 
the macports-contrib repo. Basic usage goes like this:

package require macports
mportinit

set portname python311
# Look up the port name in the PortIndex
lassign [mportlookup $portname] - infolist
array set portinfo $infolist

# Use the porturl and subport from the index to open the Portfile
set mport [mportopen $portinfo(porturl) [list subport $portinfo(name)] ""]

# Update the portinfo array with information that is not in the index
array set portinfo [mportinfo $mport]


At this point you have a portinfo array containing all the public 
information about the port. For internals like add_users you would have 
to use a private API like _mportkey:

_mportkey $mport add_users

That can get you the values of Portfile variables, but note that 
post-destroot is not a variable, it's a procedure.

It is possible to get at the Portfile interpreter and run arbitrary code 
in it, but needless to say at that point it's totally unsupported and 
subject to change without notice, you're on your own, etc.

set workername [ditem_key $mport workername]
$workername eval [list info procs]

- Josh