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updates to gas section

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small modifications for clarity

updates to delegatecall

Update introduction-to-smart-contracts.rst

modifying "write" to "transactions"

updates to gas section

small modifications for clarity

Update introduction-to-smart-contracts.rst

modifying "write" to "transactions"

updates to gas section

small modifications for clarity

updates to delegatecall
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andreb0x 2022-03-07 08:31:33 -05:00 committed by nishant-sachdeva
parent 31b5485779
commit 39f3175a37
1 changed files with 21 additions and 8 deletions
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docs/introduction-to-smart-contracts.rst
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@ -396,14 +396,15 @@ returns that code when executed.
Gas
===
Upon creation, each transaction is charged with a certain amount of **gas**,
whose purpose is to limit the amount of work that is needed to execute
the transaction and to pay for this execution at the same time. While the EVM executes the
Upon creation, each transaction is charged with a certain amount of **gas**.
Imposing a cost on operations that write to the blockchain serves to secure the network:
it deincentivizes bad actors from spamming, and pays validators (i.e. miners and stakers)
for the work that is required to validate new blocks. While the EVM executes the
transaction, the gas is gradually depleted according to specific rules.
The **gas price** is a value set by the creator of the transaction, who
The **gas price** is a value set by the creator of the transaction (see `msg.sender), who
has to pay ``gas_price * gas`` up front from the sending account.
If some gas is left after the execution, it is refunded to the creator in the same way.
If some gas is left after execution, it is refunded to the transaction originator.
If the gas is used up at any point (i.e. it would be negative),
an out-of-gas exception is triggered, which reverts all modifications
@ -415,8 +416,7 @@ Storage, Memory and the Stack
=============================
The Ethereum Virtual Machine has three areas where it can store data-
storage, memory and the stack, which are explained in the following
paragraphs.
storage, memory and the stack.
Each account has a data area called **storage**, which is persistent between function calls
and transactions.
@ -505,12 +505,25 @@ Delegatecall / Callcode and Libraries
There exists a special variant of a message call, named **delegatecall**
which is identical to a message call apart from the fact that
the code at the target address is executed in the context of the calling
contract and ``msg.sender`` and ``msg.value`` do not change their values.
<<<<<<< HEAD
contract. In practice this means ``msg.sender`` and ``msg.value`` retain
the values that were passed to the delegator, while executing code that
lives in the delegated contract.
=======
contract. In practice this means ``msg.sender`` and ``msg.value`` retain
the values that were passed to the delegator, while executing code that
lives in the delegated contract.
>>>>>>> updates to delegatecall
This means that a contract can dynamically load code from a different
address at runtime. Storage, current address and balance still
refer to the calling contract, only the code is taken from the called address.
For example, say Alice calls a method in contract A to modify
state variable `A.var` according to method ``A.foo()``.
If contract A then delegates call to contract B, the logic of `B.foo()`
will be executed, but modifications will be made to state variable `A.var`.
This makes it possible to implement the "library" feature in Solidity:
Reusable library code that can be applied to a contract's storage, e.g. in
order to implement a complex data structure.