Unified approach to string formatting.

• Version: 3.15.0
• Python: 2.7/3.4/3.5

What was wrong?

We need a well though through string handling solution for bytesXX, bytes and string types being passed into functions as arguments.

Currently, users expect to be able to provide hex encoded strings to some of these methods which either fails due to these methods expecting bytestrings, or it appears to succeed when in fact it has sent the provided hex-string as-is.

How can it be fixed?

For web3.sha3 and web3.eth.sign we have a workable solution. See https://github.com/pipermerriam/web3.py/issues/289

For bytesXX we should be able to be smart and detect hex encoded values.

• If the value is a byte string, validate len(v) == XX where XX is the bytesXX length.
• If the value is a text string, assume hex encoding. validate len(v_without_0x_prefix) == 2 * XX where XX is the bytesXX length.

For bytes types.

• If the value is a byte string, pass it through unmodified.
• If the value is a text string, validate that it is a valid hexidecimal encoded value.

For string types.

• If the value is a byte string, pass it through unmodified.
• If the value is a text string, decode it as utf8 into it’s bytes representation.

[pipermerriam]

I’ve updated the initial issue description to reflect this change.

[pipermerriam]

@veox I believe what we are trying to support is both of the following:

• demo.transact().setString("0xtentacle"); # that must be a unicode string (so in python2 u"0xtent...")
• demo.transact().setString(b"\x30\x78\x74\x65\x6e\x74\x61\x63\x6c\x65");