用于在磁盘上加载字符串和文件的函数？

发布于 2024-12-10 13:48:43 字数 427 浏览 0 评论 0原文

我有一个设计问题。我有一个用于加载图像文件的函数 loadImage() 。现在它接受一个文件路径字符串。但我也希望能够加载不在物理磁盘上的文件，例如。按程序生成。我可以让它接受一个字符串，但是它怎么知道该字符串不是文件路径而是文件数据？我可以添加一个额外的布尔参数来指定这一点，但这听起来不太干净。有什么想法吗？现在是这样的：

def loadImage(filepath):
    file = open(filepath, 'rb')
    data = file.read()
    # do stuff with data

另一个版本是

def loadImage(data):
    # do stuff with data

如何让这个函数接受“文件路径”或“数据”并猜猜它是什么？

原文

I have a design question. I have a function loadImage() for loading an image file. Now it accepts a string which is a file path. But I also want to be able to load files which are not on physical disk, eg. generated procedurally. I could have it accept a string, but then how could it know the string is not a file path but file data? I could add an extra boolean argument to specify that, but that doesn't sound very clean. Any ideas?
It's something like this now:

def loadImage(filepath):
    file = open(filepath, 'rb')
    data = file.read()
    # do stuff with data

The other version would be

def loadImage(data):
    # do stuff with data

How to have this function accept both 'filepath' or 'data' and guess what it is?

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浅忆 2024-12-17 13:48:43

您可以更改您的 loadImage 函数以期望打开的类似文件的对象，例如：

def load_image(f):
    data = file.read()

...然后从两个函数调用该函数，其中一个函数期望路径，另一个函数期望包含以下内容的字符串：数据：

from StringIO import StringIO

def load_image_from_path(path):
    with open(path, 'rb') as f:
        load_image(f)

def load_image_from_string(s):
    sio = StringIO(s)
    try:
        load_image(sio)
    finally:
        sio.close()

You can change your loadImage function to expect an opened file-like object, such as:

def load_image(f):
    data = file.read()

... and then have that called from two functions, one of which expects a path and the other a string that contains the data:

from StringIO import StringIO

def load_image_from_path(path):
    with open(path, 'rb') as f:
        load_image(f)

def load_image_from_string(s):
    sio = StringIO(s)
    try:
        load_image(sio)
    finally:
        sio.close()

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私野 2024-12-17 13:48:43

只创建两个函数，loadImageFromString 和 loadImageFromFile 怎么样？

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笑看君怀她人 2024-12-17 13:48:43

这是Python，您可以轻松地区分文件名和数据字符串。我会做这样的事情：

import os.path as P
from StringIO import StringIO
def load_image(im):
    fin = None
    if P.isfile(im):
        fin = open(im, 'rb')
    else:
        fin = StringIO(im)

    # Read from fin like you would from any open file object

其他方法是使用 try 块而不是使用 os.path，但该方法的本质保持不变。

This being Python, you can easily distinguish between a filename and a data string. I would do something like this:

import os.path as P
from StringIO import StringIO
def load_image(im):
    fin = None
    if P.isfile(im):
        fin = open(im, 'rb')
    else:
        fin = StringIO(im)

    # Read from fin like you would from any open file object

Other ways to do it would be a try block instead of using os.path, but the essence of the approach remains the same.

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