[e8a7ca2] | 1 | \chapter{Introduction} |
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| 2 | |
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| 3 | % Talk about Cforall and exceptions generally. |
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| 4 | This thesis goes over the design and implementation of the exception handling |
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| 5 | mechanism (EHM) of |
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| 6 | \CFA (pernounced sea-for-all, can also be written Cforall or CFA). |
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| 7 | Exception handling provides dynamic inter-function control flow. Although |
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| 8 | a powerful feature they tend to be expensive to use so they are often limited |
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| 9 | to unusual or ``exceptional" cases. |
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| 10 | The classic example of this is error handling, exceptions can be used to |
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| 11 | remove error handling logic from the main execution path and paying most of |
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| 12 | the cost only when the error actually occurs. |
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| 13 | |
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| 14 | % Overview of exceptions in Cforall. |
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| 15 | The \CFA EHM implements all of the common exception features (or an |
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| 16 | equivalent) found in most other EHMs and adds some features of its own. |
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| 17 | The design of all the features had to be adapted to \CFA's feature set as |
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| 18 | some of the underlying tools used to implement and express exception handling |
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| 19 | in other languages are absent in \CFA. |
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| 20 | Still the resulting syntax resembles that of other languages: |
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| 21 | \begin{cfa} |
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| 22 | try { |
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| 23 | ... |
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| 24 | T * object = malloc(request_size); |
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| 25 | if (!object) { |
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| 26 | throw OutOfMemory{fixed_allocation, request_size}; |
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| 27 | } |
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| 28 | ... |
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| 29 | } catch (OutOfMemory * error) { |
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| 30 | ... |
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| 31 | } |
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| 32 | \end{cfa} |
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| 33 | |
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| 34 | % A note that yes, that was a very fast overview. |
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| 35 | All the design and implementation of all of \CFA's EHM's features are |
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| 36 | described in detail later in this thesis, whether they are a common feature |
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| 37 | or one unique to \CFA. |
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| 38 | |
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| 39 | % The current state of the project and what it contributes. |
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| 40 | All of these features have been added to the \CFA implemenation, along with |
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| 41 | a suite of test cases. |
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| 42 | The implementation techniques are generally applicable in other programming |
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| 43 | languages and much of the design is as well, although occationally |
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| 44 | replacements for some of \CFA's more unusual feature would have to be found. |
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