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Groups > comp.lang.python > #59663

inconsistency in converting from/to hex

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We can convert from hex str to bytes with bytes.fromhex class method:

 >>> b = bytes.fromhex("ff")

But we cannot convert from hex binary:

 >>> b = bytes.fromhex(b"ff")
Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
TypeError: must be str, not bytes

We don't have bytes_instance.tohex() instance method.
But we have binascii.hexlify. But binascii.hexlify does not return an 
str. It returns a bytes instance instead.

 >>> import binascii
 >>> binascii.hexlify(b)
b'ff'

Its reverse function binascii.unhexlify can be used on str and bytes too:

 >>> binascii.unhexlify(b'ff')
b'\xff'
 >>> binascii.unhexlify('ff')
b'\xff'

Questions:

* if we have bytes.fromhex() then why don't we have bytes_instance.tohex() ?
* if the purpose of binascii.unhexlify and bytes.fromhex is the same, 
then why allow binary arguments for the former, and not for the later?
* in this case, should there be "one obvious way to do it" or not?


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inconsistency in converting from/to hex Laszlo Nagy <gandalf@shopzeus.com> - 2013-11-16 23:16 +0100
  Re: inconsistency in converting from/to hex Ned Batchelder <ned@nedbatchelder.com> - 2013-11-16 15:35 -0800
  Re: inconsistency in converting from/to hex Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-17 06:31 +0000
    Re: inconsistency in converting from/to hex Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-11-17 12:38 +0000
    Re: inconsistency in converting from/to hex Serhiy Storchaka <storchaka@gmail.com> - 2013-11-17 18:22 +0200

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