You've already forked macports-base
mirror of
https://github.com/macports/macports-base.git
synced 2026-07-12 18:18:43 -07:00
Christopher Chavez
57 lines
2.7 KiB
Plaintext
57 lines
2.7 KiB
Plaintext
MacPorts Internals:
|
|
|
|
The MacPorts system is composed of three TCL libraries:
|
|
macports - public API
|
|
port - portfile parsing and execution
|
|
pextlib - necessary C extensions to TCL
|
|
|
|
These three TCL libraries are grouped as TCL "packages". They allow
|
|
for complex versioning and have a provide/require model of use, making
|
|
them well suited for maintaining a backwards compatible ports system.
|
|
|
|
The "macports" TCL Library provides a public API into the MacPorts
|
|
system. Any external application wishing to manipulate a port can
|
|
load the "macports" TCL library. 'port', the included command line port
|
|
utility, uses only the exported "macports" API.
|
|
|
|
The "macports" API provides very simple primitives for dealing with
|
|
ports (ie, mportexec/mportopen/mportinit). Also, the API has very little
|
|
knowledge of the contents of a portfile; instead, it relies entirely upon
|
|
the "port" TCL library. By keeping the high level API simple and generic,
|
|
a revision of the underlying ports system will not necessarily require
|
|
a revision of the high level "macports" API.
|
|
|
|
TCL packages allow for complex versioning with a strong requires/provides
|
|
model; this means that a revision of the API at any level will not break
|
|
backwards compatibility.
|
|
|
|
When parsing a port, the "macports" library loads the Portfile into a
|
|
sub-interpreter. The "port" library and all port-specific code is run
|
|
entirely within this sub-interpreter, and thus can never pollute the TCL
|
|
space of other ports, the "macports" library, or the calling application.
|
|
|
|
The "macports" library is also responsible for loading user specified
|
|
options into the sub-interpreter to be evaluated by the "ports" library. In
|
|
that case it sets the variable name in the sub-interpreter and adds the
|
|
option to the sub-interpreter's global array user_options(). User options
|
|
are passed as part of the call to mportopen.
|
|
|
|
The "port" TCL package provides all the primitives required for a mac
|
|
portfile to be parsed, queried, and its actions executed. It also provides
|
|
a single procedure call that the "macports" TCL package uses to kick off
|
|
execution: "eval_targets".
|
|
|
|
The port TCL package is loaded by every Portfile with the following line
|
|
at the start of the Portfile:
|
|
PortSystem <version required>
|
|
The version should be set to the version of the port API required to build
|
|
your port. Currently the only version supplied is 1.0.
|
|
|
|
Because a port is not actually parsed, but in fact executed in the TCL
|
|
interpreter, every port option must be a TCL procedure. The ports library
|
|
supplies all these procedures, all of which are generated at run-time using
|
|
the "options" procedure in portutil.tcl.
|
|
|
|
The "pextlib" TCL library provides a variety of otherwise unavailable TCL
|
|
procedures, such as an interface to flock(2).
|