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Diffstat (limited to 'docs/layout-of-source-files.rst')
| -rw-r--r-- | docs/layout-of-source-files.rst | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/docs/layout-of-source-files.rst b/docs/layout-of-source-files.rst index c21e7280..a0170c5a 100644 --- a/docs/layout-of-source-files.rst +++ b/docs/layout-of-source-files.rst @@ -6,6 +6,8 @@ Source files can contain an arbitrary number of contract definitions and include .. index:: source file, ! import +.. _import: + Importing other Source Files ============================ @@ -68,15 +70,20 @@ remappings so that e.g. ``github.com/ethereum/dapp-bin/library`` is remapped to ``/usr/local/dapp-bin/library`` and the compiler will read the files from there. If remapping keys are prefixes of each other, the longest is tried first. This allows for a "fallback-remapping" with e.g. ``""`` maps to -``"/usr/local/include/solidity"``. +``"/usr/local/include/solidity"``. Furthermore, these remappings can +depend on the context, which allows you to configure packages to +import e.g. different versions of a library of the same name. **solc**: -For solc (the commandline compiler), these remappings are provided as ``key=value`` -arguments, where the ``=value`` part is optional (and defaults to key in that +For solc (the commandline compiler), these remappings are provided as +``context:prefix=target`` arguments, where both the ``context:`` and the +``=target`` parts are optional (where target defaults to prefix in that case). All remapping values that are regular files are compiled (including their dependencies). This mechanism is completely backwards-compatible (as long -as no filename contains a =) and thus not a breaking change. +as no filename contains = or :) and thus not a breaking change. All imports +in files in or below the directory ``context`` that import a file that +starts with ``prefix`` are redirected by replacing ``prefix`` by ``target``. So as an example, if you clone ``github.com/ethereum/dapp-bin/`` locally to ``/usr/local/dapp-bin``, you can use @@ -92,6 +99,19 @@ and then run the compiler as solc github.com/ethereum/dapp-bin/=/usr/local/dapp-bin/ source.sol +As a more complex example, suppose you rely on some module that uses a +very old version of dapp-bin. That old version of dapp-bin is checked +out at ``/usr/local/dapp-bin_old``, then you can use + +.. code-block:: bash + + solc module1:github.com/ethereum/dapp-bin/=/usr/local/dapp-bin/ \ + module2:github.com/ethereum/dapp-bin/=/usr/local/dapp-bin_old/ \ + source.sol + +so that all imports in ``module2`` point to the old version but imports +in ``module1`` get the new version. + Note that solc only allows you to include files from certain directories: They have to be in the directory (or subdirectory) of one of the explicitly specified source files or in the directory (or subdirectory) of a remapping |