ae2aaaa436 Add `script_pubkey_lens` method (Martin Habovstiak)
cf068d16b0 Implement transaction weight prediction (Martin Habovstiak)
Pull request description:
When creating a transaction one must know the the fee beforehand to set
appropriate amounts for outputs and to know the fee, weight is required.
So far we only had a method on an already-constructed transaction. This
method clearly wasn't helpful when constructing the transaction except
for hacks like temporarily adding an all-zeroes signature.
This change adds a function that can compute the transaction weight
without knowing individual bytes of the scripts, witnesses and other
elements. It only needs to know their sizes.
To make the API less error-prone a special, trivial, type is also added
for computing the lengths of witnesses.
Based on #1627
ACKs for top commit:
apoelstra:
ACK ae2aaaa436
tcharding:
ACK ae2aaaa436
Tree-SHA512: 55376601c2c2826bb0909cc25ff5b65816f0b1a2d57fb2cd8831f3db5382de0f4a364d518b312f0528bb5f44c30f3f74f8d254145eed2bfd65e2332b7c4d7c8b
f00b6362a0