Yashotantra Academy logo
← Vyper theorytheory 0/50 · 0%
level 1
Curious · 0 XP
streak
0d
perfect
0
badges
0

100 XP to Apprentice

Web3 integration · medium

22. Sending ETH: send, raw_call and default

Moving value out of a contract safely.

1 min read3 questionsup to 50 XPtopic 22/50

Read in another language

AI translates the explanation and quiz text while preserving code and answer scoring.

`send(to, amount)` forwards a small fixed gas stipend and reverts on failure — good for simple payouts. For calling arbitrary contracts with data or more gas, use `raw_call(to, data, value=amount)`.

@external
def withdraw():
    amount: uint256 = self.balances[msg.sender]
    self.balances[msg.sender] = 0
    send(msg.sender, amount)

@external
@payable
def __default__():
    pass

`__default__` is Vyper's fallback function — it runs when a call doesn't match any function selector, similar to Solidity's `fallback`/`receive`.

How to study this topic

  1. 1. Read the explanation once end to end, skipping the code.
  2. 2. Re-read the code snippets and say out loud what each line does.
  3. 3. Answer the quiz without scrolling back — that is the real check.
  4. 4. Read every explanation, even for the answers you got right.

Scoring

  • · Up to 30 XP from quiz accuracy.
  • · +15 XP for a perfect first attempt.
  • · +5 XP while a 3-day streak is running.
  • · 75% or higher marks the topic complete.

Check your understanding

  1. 1. What does `send(to, amount)` do on failure?

  2. 2. Which builtin lets you forward custom data and gas to another contract?

  3. 3. What is `__default__` equivalent to in Solidity?

Badges

First light
Pass your first topic
Sharp shooter
3 perfect first-try quizzes
On a roll
Study 3 days in a row
Week warrior
Study 7 days in a row
Grinder
Earn 500 XP
Deep diver
Earn 1500 XP