how to set gas price and gas limit for a trade ?

[tanpv]

hi, using uniswap-python lib, Could I set the gas price and gas limit for the trade ?
seem I do not find this from readme document, please help

also have same question with slip page setting.
Do we support this in near future ?

[ErikBjare]

Duplicate of #23.

You need to pass in a custom Web3 instance to the constructor, with the gas strategy that you want. See the Web3 docs for how to do that: https://web3py.readthedocs.io/en/stable/gas_price.html

also have same question with slippage setting.

There's a constructor parameter for that as well: https://github.com/shanefontaine/uniswap-python/blob/672ce87c9f330a20bb5f17742d65eafbaf484e80/uniswap/uniswap.py#L132

[tanpv]

many thanks @ErikBjare

[stamatelou]

@ErikBjare were you able to pass the instance to the constructor? And if yes, in which part of the uniswap.py script you added the instance from web3 ?

[alb2001]

@ErikBjare Could you please provide an example on this
I've been taking a look at the uniswap.py class, but I cannot seem to figure out how you would pass that w3 parameter in the constructor and what you would need to put there.

something like this doesn't work
uniswap_wrapper = Uniswap(address=eth_address, private_key=eth_priv_key, provider=eth_infura_node, web3=web3.gas_strategies.time_based.fast_gas_price_strategy)

[ErikBjare]

You need to pass a Web3 object, not a gas strategy object. Read the Web3py docs:

• https://web3py.readthedocs.io/en/stable/quickstart.html
• https://web3py.readthedocs.io/en/stable/providers.html

The provider and web3 parameters are mutually exclusive. The former is essentially just a shorthand for the latter.

For specifics on the behavior, see the first few lines of Uniswap.__init__:
https://github.com/shanefontaine/uniswap-python/blob/5ec7a1c5c6d861f90d935ab5faf680d2ab3aa112/uniswap/uniswap.py#L143-L150

[alb2001]

Hello @ErikBjare

Thanks a lot. Correct. WHat I did was creating a w3 instance like this:

w3 = Web3(Web3.HTTPProvider(eth_infura_node, request_kwargs={"timeout": 60})) w3.eth.setGasPriceStrategy(fast_gas_price_strategy)

Then pass it through the w3 argument of the Uniswap constructor class. Seems it worked. But would you add this as a parameter on the class where we can specify the gwei directly? I think it's much easier.

[ErikBjare]

But would you add this as a parameter on the class where we can specify the gwei directly? I think it's much easier.

That would not be appropriate. It might make your code slightly shorter, but it unnecessarily complicates the code for uniswap-python to handle all the complexities of Web3 initialization and gas pricing strategies.

As the Zen of Python states: "there should be one, and preferably only one, obvious way to do it"

[alb2001]

Thank you

[Marsh-James]

I'm happy to make a PR for overwriting the default gas limit if you have a preference for how it should be passed in. Such as in the constructor or with each individual make_trade call or by some other means.

@Weizilla Makes an interesting point, any thoughts @ErikBjare? Was there a particular rationale behind this?

[troublesprouter]

Was a simple and quick way to make the transaction very fast found? I'm finding that using a custom web3 makes the process much slower, defeating the process of making the transaction faster.