Python2.7: Initialize constructor variable as byte array

Question

I know this C# code:

public class ClassA
{
    public byte var1;
}

can be converted to this Python code:

class ClassA(object):
    def __init__(self):
        self.var1 = bytes() # or b''

but what if var1 were instead a byte array as follows:

public byte[] var1;

Normally, I would do:

[bytes(i) for i in myList]

but no such variable like myList exists in this case to fill that position, leaving me with [bytes(i) for i in ] which is obviously syntactically invalid.

Related to Mimic C# classes in Python

user2357112 · Accepted Answer · 2018-09-18 17:22:37Z

2

bytes() is not the equivalent of a C# byte. There is no direct equivalent of a C# byte in Python; the closest would be an ordinary int. I would consider the most direct translation of that C# class to be

class ClassA(object):
    def __init__(self):
        self.var1 = 0

bytes objects are immutable sequences of bytes. If you want a mutable sequence of bytes, either a bytearray or an ordinary list would be appropriate, or an array.array array. I'd probably go with the list unless I had specific reason to do otherwise, really:

class ClassA(object):
    def __init__(self):
        self.var1 = []

Note that bytearray and bytes represent sequences of unsigned bytes; their elements go from 0 to 255, not from -128 to 127. An array.array('b') would be a sequence of signed bytes.

answered Sep 18, 2018 at 17:22

user2357112

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5 Comments

Ctrl S Over a year ago

What makes 0 more concise than bytes() or b''? I am less familiar with this topic.

user2357112 Over a year ago

@CtrlS: It's not about what's more concise; it's about writing code that actually means the right thing. (0 is more concise, being 1 character instead of 7 or 3, but that doesn't matter.)

Ctrl S Over a year ago

Maybe concise was the wrong word...what I'm really asking I guess then is how do bytes() and 0 differ?

user2357112 Over a year ago

@CtrlS: bytes() is an immutable sequence of 0 bytes. 0 is the integer 0.

Ctrl S Over a year ago

So the difference is that bytes() implies multiple bytes, whereas 0 is obviously a single value. Okay, thanks.

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