如何防止python解释器查看和导入未安装的模块； 不属于系统？

Question

Short version of the question:

How do I prevent python interpreter to see and import modules that are not installed; do not belong to the system I am using; and are not required if I choose to run the code under System X instead of System Y?

From a C perspective I would do something on those lines:

#if defined(__SerialCOM__)
// Do stuff, import stuff
#elif defined(__SPI_Over_Raspberry__)
// Do stuff, import stuff
#elif defined(__SPI_Over_BeagleBone__)
// Do stuff, import stuff
#endif

I would like to avoid creating different projects for different boards. This I know how to do.

---

Long Version

I am trying to implement in my project an interface to communicate to an ADC IC from texas. The end goal is to be able to read from it with several different devices:

ADC <---SPIbus (With C code)---> ArduinoDue <-----Serial (With Python)----> LinuxPC
ADC <---SPIbus (With Python)---> Raspberry Pi3
ADC <---SPIbus (With Python)---> BeagleBone Black
ADC <---SPIbus (With Python)---> Intel Edson

For such, I created an interface, that receives a reader object, this reader object inherits from an abstract reader class.

I would like to avoid creating different projects for different boards. This I know how to do.

readerhandler.py

from readers import SerialReader,PiSPIreader


class ReaderHandler:
    def __init__(self, readertype="PiSPI"):
        self.reader = self.getreader(readertype)

    def getreader(self, readertype):
        aReader = []
        if readertype == "PiSPI":
            aReader = PiSPIreader()
        elif readertype == "Serial":
            aReader = SerialReader()
        elif readertype == "BBSPI":
            aReader = BBSPIreader()
        else:
            print("reader type invalid")
        return aReader
    # Do other stuff

readers.py

from abc import ABCMeta, abstractmethod
import serial  # For Serial Reader object (Should only be interpreted in a pc device)
import piSPI  # For piSPI Reader object (Should only be interpreted in a RasberryPi device)
import bbSPI  # For bbSPI Reader object (Should only be interpreted in a BeagleBone Black device)


class Reader(object): # My abstract class
    __metaclass__ = ABCMeta

    @abstractmethod
    def initialization(self):
    """Acquisitions setup"""

    @abstractmethod
    def _run(self):
        """function that acquires sample from device port on the bakcground"""

    @abstractmethod
    def readdata(self, nofsamples=100):
    """Read X buffered samples"""

class SerialReader(Reader): # (Should only be interpreted in a PC device)
    def __init__(self, portname='/dev/ttyACM2', baudrate=115200, magic0=0x42, magic1=0x41):
        super(SerialReader, self).__init__()
        self.ser = serial.Serial(portname, baudrate=baudrate, bytesize=serial.EIGHTBITS, parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, timeout=None)

    # Implements other abstract methods and **uses Serial object***


class PiSPIreader(Reader): # (Should only be interpreted in a Rasberry device)
    def __init__(self):
        super(PiSPIreader, self).__init__()
        self.piSPI = piSPI.SPI()

    # Implements other abstract methods and **uses piSPI object***


class BBSPIreader(Reader): # (Should only be interpreted in a BeagleBone Black device)
    def __init__(self):
        super(BBSPIreader, self).__init__()
        self.bbSPI = bbSPI.SPI()

    # Implements other abstract methods and **uses bbSPI object***

Answer 1

Use try/except .

try:
    import serial
except ImportError:
    pass    # couldn't import serial, so do nothing
else:       # we successfully imported serial, so define the class that uses it

    class SerialReader(Reader): # (Should only be interpreted in a PC device)
        def __init__(self, portname='/dev/ttyACM2', baudrate=115200, magic0=0x42, magic1=0x41):
            super(SerialReader, self).__init__()
            self.ser = serial.Serial(portname, baudrate=baudrate, bytesize=serial.EIGHTBITS, parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, timeout=None)

        # Implements other abstract methods and **uses Serial object***

Answer 2

How to check if a python module exists without importing it

you may also use os.name, for detecting the device kind.