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| author | Mike <mikro2nd@users.noreply.github.com> | 2018-06-29 18:21:39 +0800 |
|---|---|---|
| committer | chriseth <chris@ethereum.org> | 2018-06-29 18:21:39 +0800 |
| commit | 2a9d54af587c300d9dc5984a796200795302137d (patch) | |
| tree | d0662a0eeda89880972fef5f9253d0c753ae00c9 | |
| parent | c9cab803892a09386617faab6b4e1580ee2eaa47 (diff) | |
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Clarify scope of 'using A for B' (#4252)
* Issue 1213: Clarify scope of 'using A for B'
* Typo fix.
* Further restructuring and clarification of contracts doc.
* Revert closer to original wording and formatting.
| -rw-r--r-- | docs/contracts.rst | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/docs/contracts.rst b/docs/contracts.rst index 5cfa7805..845fd973 100644 --- a/docs/contracts.rst +++ b/docs/contracts.rst @@ -1402,24 +1402,25 @@ Using For ********* The directive ``using A for B;`` can be used to attach library -functions (from the library ``A``) to any type (``B``). +functions (from the library ``A``) to any type (``B``). These functions will receive the object they are called on -as their first parameter (like the ``self`` variable in -Python). +as their first parameter (like the ``self`` variable in Python). The effect of ``using A for *;`` is that the functions from -the library ``A`` are attached to any type. +the library ``A`` are attached to *any* type. -In both situations, all functions, even those where the -type of the first parameter does not match the type of -the object, are attached. The type is checked at the +In both situations, *all* functions in the library are attached, +even those where the type of the first parameter does not +match the type of the object. The type is checked at the point the function is called and function overload resolution is performed. -The ``using A for B;`` directive is active for the current -scope, which is limited to a contract for now but will -be lifted to the global scope later, so that by including -a module, its data types including library functions are +The ``using A for B;`` directive is active only within the current +contract, including within all of its functions, and has no effect +outside of the contract in which it is used. The directive +may only be used inside a contract, not inside any of its functions. + +By including a library, its data types including library functions are available without having to add further code. Let us rewrite the set example from the |