easy_install.py 文件源码

def save(self):
        """Write changed .pth file back to disk"""
        if not self.dirty:
            return

        data = '\n'.join(map(self.make_relative,self.paths))
        if data:
            log.debug("Saving %s", self.filename)
            data = (
                "import sys; sys.__plen = len(sys.path)\n"
                "%s\n"
                "import sys; new=sys.path[sys.__plen:];"
                " del sys.path[sys.__plen:];"
                " p=getattr(sys,'__egginsert',0); sys.path[p:p]=new;"
                " sys.__egginsert = p+len(new)\n"
            ) % data

            if os.path.islink(self.filename):
                os.unlink(self.filename)
            f = open(self.filename,'wt')
            f.write(data); f.close()

        elif os.path.exists(self.filename):
            log.debug("Deleting empty %s", self.filename)
            os.unlink(self.filename)

        self.dirty = False