Python：将脚本从过程式转换为面向对象风格

Question

我写了一个简单的Munin插件，用来绘制平均风扇转速的图表。现在我想把它重做成面向对象编程（OOP）的风格，这主要是为了学习。不过我不知道从哪里开始。有没有人愿意给我一些指导，或者给我一个完成后这个脚本应该是什么样子的例子？我还打算用这种风格重做其他一些脚本，也是为了学习。

import sys
import subprocess

CMD = "/usr/sbin/omreport chassis fans".split()

# Munin populates sys.argv[1] with "" (an empty argument), lets remove it.
sys.argv = [x for x in sys.argv if x]

if len(sys.argv) > 1:
    if sys.argv[1].lower() == "autoconfig":
        print "autoconfig"
    elif sys.argv[1].lower() == "config":
        print "graph_title Average Fan Speed"
        print "graph_args --base 1000 -l 0"
        print "graph_vlabel speed (RPM)"
        print "graph_category Chassis"
        print "graph_info This graph shows the average speed of all fans"
        print "graph_period second"
        print "speed.label speed"
        print "speed.info Average fan speed for the five minutes."
else:
    try:
        data = subprocess.Popen(CMD,stdout=subprocess.PIPE).stdout.readlines()
    except OSError, e:
        print >> sys.stderr, "Error running '%s', %s" % (" ".join(cmd), e)
        sys.exit(1)

    count = total = 0
    for item in data:
        if "Reading" in item:
            # Extract variable length fan speed, without regex.
            total += int(item.split(":")[1].split()[0])
            count += 1
    # Sometimes omreport returns zero output if omsa services aren't started.
    if not count or not total:
        print >> sys.stderr, 'Error: "omreport chassis fans" returned 0 output.'
        print >> sys.stderr, 'OMSA running? Try: "srvadmin-services.sh status".'
        sys.exit(1)

    avg = (total / count)
    print "speed.value %s" % avg

Answer 1

你可以通过找出那些一起使用的代码和数据来用面向对象编程（OOP）重做它们。然后把这些代码和数据合并成“类”。

你上面提到的数据看起来像是一个过程的输出。代码是在对这些数据进行遍历。我想如果你想的话，可以把它做成一个类，但这样做有点儿傻。:)

所以，像这样（显然这段代码完全没有经过测试）：

import sys
import subprocess

class Fanspeed(object):

    def __init__(self, command):
        self.command = command.split()

    def average_fan_speed(self):
        data = subprocess.Popen(CMD,stdout=subprocess.PIPE).stdout.readlines()

        count = total = 0
        for item in data:
            if "Reading" in item:
                # Extract variable length fan speed, without regex.
                total += int(item.split(":")[1].split()[0])
                count += 1
        # Sometimes omreport returns zero output if omsa services aren't started.
        if not count or not total:
            raise ValueError("I found no fans. Is OMSA services started?"

        avg = (total / count)
        return % avg

if __main__ == '__main__':
    # Munin populates sys.argv[1] with "" (an empty argument), lets remove it.
    sys.argv = [x for x in sys.argv if x]

    if len(sys.argv) > 1:
        if sys.argv[1].lower() == "autoconfig":
            print "autoconfig"
        elif sys.argv[1].lower() == "config":
            print "graph_title Average Fan Speed"
            print "graph_args --base 1000 -l 0"
            print "graph_vlabel speed (RPM)"
            print "graph_category Chassis"
            print "graph_info This graph shows the average speed of all fans"
            print "graph_period second"
            print "speed.label speed"
            print "speed.info Average fan speed for the five minutes."
    else:
        try:
            cmd = "/usr/sbin/omreport chassis fans"
            fanspeed = Fanspeed(cmd)
            average = fanspeed.average_fan_speed()
        except OSError, e:
            print >> sys.stderr, "Error running '%s', %s" % (cmd, e)
            sys.exit(1)
        except ValueError, e:
            # Sometimes omreport returns zero output if omsa services aren't started.
            print >> sys.stderr, 'Error: "omreport chassis fans" returned 0 output.'
            print >> sys.stderr, 'OMSA running? Try: "srvadmin-services.sh status".'
            sys.exit(1)

不过，具体情况可能会有所不同。这或许会更清晰一些。