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33 lines
1.4 KiB
ReStructuredText
33 lines
1.4 KiB
ReStructuredText
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.. highlight:: kotlin
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.. raw:: html
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<script type="text/javascript" src="_static/jquery.js"></script>
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<script type="text/javascript" src="_static/codesets.js"></script>
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Updating the contract
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=====================
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Remember that each state references a contract. The contract imposes constraints on transactions involving that state.
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If the transaction does not obey the constraints of all the contracts of all its states, it cannot become a valid
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ledger update.
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We need to modify our contract so that the lender's signature is required in any IOU creation transaction. This will
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only require changing a single line of code. In ``IOUContract.java``/``IOUContract.kt``, update the final line of the
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``requireThat`` block as follows:
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.. container:: codeset
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.. code-block:: kotlin
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"The borrower and lender must be signers." using (command.signers.containsAll(listOf(
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out.borrower.owningKey, out.lender.owningKey)))
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.. code-block:: java
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check.using("The borrower and lender must be signers.", command.getSigners().containsAll(
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ImmutableList.of(borrower.getOwningKey(), lender.getOwningKey())));
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Progress so far
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---------------
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Our contract now imposes an additional constraint - the lender must also sign an IOU creation transaction. Next, we
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need to update ``IOUFlow`` so that it actually gathers the counterparty's signature as part of the flow.
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