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chriseth 2020-05-25 23:42:15 +02:00
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1
Changelog.md
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@ -1,6 +1,7 @@
### 0.6.9 (unreleased) ### 0.6.9 (unreleased)
Language Features: Language Features:
* Permit calldata location for all variables.
Compiler Features: Compiler Features:

13
docs/types/reference-types.rst
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@ -13,8 +13,7 @@ arrays and mappings. If you use a reference type, you always have to explicitly
provide the data area where the type is stored: ``memory`` (whose lifetime is limited provide the data area where the type is stored: ``memory`` (whose lifetime is limited
to an external function call), ``storage`` (the location where the state variables to an external function call), ``storage`` (the location where the state variables
are stored, where the lifetime is limited to the lifetime of a contract) are stored, where the lifetime is limited to the lifetime of a contract)
or ``calldata`` (special data location that contains the function arguments, or ``calldata`` (special data location that contains the function arguments).
only available for external function call parameters).
An assignment or type conversion that changes the data location will always incur an automatic copy operation, An assignment or type conversion that changes the data location will always incur an automatic copy operation,
while assignments inside the same data location only copy in some cases for storage types. while assignments inside the same data location only copy in some cases for storage types.
@ -26,9 +25,9 @@ Data location
Every reference type has an additional Every reference type has an additional
annotation, the "data location", about where it is stored. There are three data locations: annotation, the "data location", about where it is stored. There are three data locations:
``memory``, ``storage`` and ``calldata``. Calldata is only valid for parameters of external contract ``memory``, ``storage`` and ``calldata``. Calldata is a non-modifiable,
functions and is required for this type of parameter. Calldata is a non-modifiable,
non-persistent area where function arguments are stored, and behaves mostly like memory. non-persistent area where function arguments are stored, and behaves mostly like memory.
It is required for parameters of external functions but can also be used for other variables.
.. note:: .. note::
@ -36,6 +35,12 @@ non-persistent area where function arguments are stored, and behaves mostly like
depending on the kind of variable, function type, etc., but all complex types must now give an explicit depending on the kind of variable, function type, etc., but all complex types must now give an explicit
data location. data location.
.. note::
If you can, try to use ``calldata`` as data location because it will avoid copies and
also makes sure that the data cannot be modified. Arrays and structs with ``calldata``
data location can also be returned from functions, but it is not possible to
allocate such types.
.. _data-location-assignment: .. _data-location-assignment:
Data location and assignment behaviour Data location and assignment behaviour