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Author:Peter Gummer

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Date:2009-05-20T15:21:50.000000Z


git-svn-id: https://svn.eiffel.com/eiffel-org/trunk@222 abb3cda0-5349-4a8f-a601-0c33ac3a8c38
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pgummer
2009-05-20 15:21:50 +00:00
parent fe9cef0e9b
commit 380dd8abe4
3 changed files with 15 additions and 8 deletions
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13
documentation/current/method/void-safe-programming-eiffel/converting-existing-software-void-safety/index.wiki
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@@ -107,6 +107,7 @@ Next you fix the problems that the compiler discovered. The compiler errors conc
Let's look at some specific cases and how fixing them unfolds.
===Variables not properly set===
[[Image:VoidSafeVEVI1]]
@@ -144,7 +145,7 @@ Here attribute declarations for <code>my_nvp</code> and <code>my_nvp_list</code>
</code>
In second case, there is also an Initialization rule violation (VEVI), this time on <code>Result</code>, in this routine:
In a second case, there is also an Initialization rule violation (VEVI), this time on <code>Result</code>, in this routine:
<code>
at_first (nm: STRING): NVP is
@@ -178,9 +179,11 @@ So the least impact to this routine will be to declare its type as <code>detacha
</code>
The same change is made in other routines that can return void by design.
The same change is made in other routines that can return void by design, particularly including a routine called <code>value_at_first</code>, which gets our attention next.
The change to <code>at_first</code> satisfies the VEVI issue in <code>at_first</code>, but it introduces a previously unseen conformance issue (VJAR) in a routine <code>value_at_first</code>:
===Source of assignment does not conform to target===
The change to <code>at_first</code> satisfies the VEVI issue in <code>at_first</code>, but it introduces a previously unseen conformance issue (VJAR) in the routine <code>value_at_first</code>:
[[Image:VoidSafeVJAR1]]
@@ -226,6 +229,10 @@ Here the '''attached syntax''' can fix the problem and streamline the routine:
In this version <code>tn</code> need not be declared as a local variable. Remember that the attached syntax provides a fresh local variable, if the expression is not void.
===Both VEVI and VJAR errors===
A design issue in class <code>NVP_LIST</code> causes issues of both conformance and initialization. In the original design, an instance of the class NVP_LIST could traverse its contents NVP-by-NVP with inherited functionality. But it also could traverse its contents returning "sublists" based on recurring patterns of the <code>name</code> attributes of a sequence of name/value pairs.
==Code patterns==